AQUEOUS LUBRICANT COMPOSITION FOR METALWORKING

Description

Technical field

[0001] The present invention relates to the field of lubricating compositions, and more particularly to lubricating compositions used in metalworking processes, such as machining operations of metal parts. In particular, the present invention relates to aqueous-based lubricating compositions. Prior art

[0002] Lubricating compositions, also known as "lubricants," are commonly used in mechanical systems to reduce friction between parts and thus protect them against wear. In addition to wear, friction can oppose the relative movement of parts in contact and cause energy losses that are detrimental to optimal operation of the mechanical system.

[0003] Lubricants are used for a wide range of applications, from the lubrication of combustion vehicle engines to the lubrication of machines used for machining operations, commonly known as metalworking, particularly for metal deformation operations.

[0004] Metalworking generally refers to the implementation of mechanical or metallurgical processes, both diversified and more specialized, which can be defined as shaping, cutting or joining processes. It can also concern any mechanical transformation of metal, such as machining (turning, milling, drilling, sawing, threading among others), forming, cutting, stamping, or even rolling.

[0005] Metalworking operations particularly require the use of lubricating compositions, with the aim of reducing friction forces between the metal parts in contact and preventing their premature wear, while advantageously ensuring cooling of the latter.

[0006] These lubricating compositions, dedicated to lubrication in metal machining processes, are also commonly referred to as “metalworking compositions or fluids”, “machining lubricants or fluids” or “cutting lubricants or fluids”.

[0007] Conventionally, the lubricant formulations used for such machining operations are lubricants composed mainly of one or more base oils, to which are generally associated additives dedicated to boosting the lubricating performance of the base oils, such as friction modifier additives. Generally speaking, these lubricant formulations are classified according to the type of oil they incorporate. Thus: Mineral fluids, non-renewable, are those comprising mineral oils, such as paraffinic, aromatic or naphthenic oils, in their basic formulation; Renewable fluids, of vegetable or animal origin, are those comprising vegetable, animal oils or fats in their basic formulation; Mineral fluids of synthetic origin are those comprising mineral oils or chemically modified petrochemical derivatives, in their basic formulation such as, for example, polyalphaolefins, polyalkylene glycols and hydrogenated mineral oils; Renewable fluids of synthetic origin are those comprising chemically modified vegetable or animal oils, in their basic formulation such as, for example, vegetable oil esters, sulphated, oxidised, esterified vegetable oils, or sulphated animal oils.

[0008] Some formulations, called mixed, include a mixture of the oils listed above in their base formulation. The best known are called semi-synthetic oils and correspond to a mixture of synthetic and mineral oils.

[0009] However, there are several disadvantages to using oils or greases in metalworking lubricant compositions. In particular, oil-based lubricants generally have low resistance to microbial attack, poor cooling properties, or a negative impact on the working environment, health, or safety.

[0010] Emulsion lubricants, comprising an aqueous phase added to an oily phase, have been developed. However, these lubricants exhibit poor stability, partly due to water hardness and / or salinity.

[0011] In order to solve the problems associated with the implementation of oil-based lubricant formulations in metalworking applications, water-based compositions have shown some interest. These formulations generally include water, supplemented with various additives to ensure the tribological properties required for lubricants, particularly in terms of friction reduction and protection of parts against wear.

[0012] As examples, we can cite documents WO 2009 / 106359 and WO 2012 / 163550 which describe aqueous lubricating compositions comprising in particular water and carboxymethylcellulose salts.

[0013] Also exemplified is EP 3 042 946 which provides an oil- and emulsifier-free metalworking fluid comprising between 0.1 and 2% by weight of a cellulose-type polymer.

[0014] Finally, GB 1 272 100 proposes an aqueous metalworking lubricant comprising (1) a linear polypropylene glycol or an ethylene oxide / propylene oxide copolymer with a molecular weight of between 2,000 and 9,000 Da, and (2) a polyvinyl pyrrolidone, a cellulose ether or a triethanolamine phosphate.

[0015] EP 0 288 375 A1 describes an aqueous functional fluid for metalworking with improved extreme pressure properties.

[0016] For obvious reasons, optimizing the performance of aqueous lubricants for metalworking is an ongoing objective. In particular, the aim is to constantly improve the tribological properties of lubricants, especially anti-wear and extreme pressure properties. Statement of the invention

[0017] The present invention thus provides a new aqueous lubricating composition having improved tribological properties, in particular anti-wear and extreme pressure, suitable for its use in metalworking,

[0018] Thus, the present invention relates, according to a first of its aspects, to an aqueous lubricating composition, in particular for metalworking, comprising at least: at least 50% by mass of water, preferably osmosis water; from 0.01% to 10% by mass of at least one polysaccharide; from 0.1% to 10% by mass of at least one alkoxylated, in particular ethoxylated, castor oil; from 0.1% to 10% by mass of at least one sulfur and / or phosphorus anti-wear compound, the percentages being expressed in relation to the total mass of the composition.

[0019] According to one embodiment, an aqueous lubricating composition according to the invention further comprises at least one polyalkylene glycol, in particular as described in the remainder of the text.

[0020] For the purposes of the present invention, the term "aqueous composition" is intended to denote a composition comprising water as a base fluid, in other words as the major solvent. In particular, the water, preferably osmosed, represents at least 50% by mass of the total mass of the lubricating composition.

[0021] In the remainder of the text, the term “aqueous lubricating composition” or “aqueous lubricant” will refer to a lubricating composition according to the invention.

[0022] For the purposes of the present invention, the term "osmosed water" is intended to denote water that has undergone purification, in particular by a reverse osmosis process, in order to reduce the content of organic and / or mineral compounds, for example to a content of less than 5.0% by weight, preferably less than 1.0% by weight. In the remainder of the text, the expressions "demineralized water" or "ultrapure water" will be considered equivalent or synonymous with the expression "osmosed water". In particular, osmosed water may be "deionized water", in other words water that has undergone purification in order to reduce the content of ions, such as the Ca 2+< and HCO 3 -< ions generally present in water. Preferably, deionized water does not comprise ions.

[0023] Against all expectations, the inventors have discovered that the combined use of at least one polysaccharide, an alkoxylated castor oil, in particular ethoxylated, and at least one phosphorus and / or sulfur anti-wear compound, makes it possible to obtain an aqueous fluid with excellent tribological properties, in particular under extreme pressure conditions, suitable for its use as a lubricant for metalworking.

[0024] In particular, as illustrated in the examples which follow, the inventors have shown that it is possible, by supplementing an aqueous lubricating formulation comprising at least one polysaccharide, by the specific association of at least one sulfur and / or phosphorus anti-wear agent and an alkoxylated, preferably ethoxylated, castor oil, to significantly improve the tribological properties of the aqueous lubricating formulation, in particular the anti-wear and extreme pressure properties.

[0025] The combination of at least one alkoxylated, in particular ethoxylated, castor oil and at least one sulfur and / or phosphorus anti-wear compound, in an aqueous lubricating composition comprising at least one polysaccharide, unexpectedly exhibits a synergistic effect on improving the anti-wear and extreme pressure properties of the aqueous lubricant.

[0026] The aqueous lubricating composition according to the invention thus exhibits improved friction reduction performance, in particular under extreme pressure conditions, compared to a composition not comprising alkoxylated castor oil or anti-wear compound according to the invention.

[0027] The anti-wear and extreme pressure properties can be evaluated by a 4-ball extreme pressure test, in particular according to ASTM D2783, as detailed in the examples below. As demonstrated in the examples, an aqueous lubricant composition according to the invention achieves high weld load values, without a significant increase in the wear diameter, which demonstrates its excellent tribological properties.

[0028] The invention thus relates to the use of the combination of at least one alkoxylated castor oil, in particular ethoxylated, and at least one phosphorus and / or sulfur anti-wear compound, in particular sulfur, in an aqueous lubricating composition comprising at least one polysaccharide, to improve its anti-wear and / or extreme pressure properties.

[0029] Thus, the aqueous compositions according to the invention prove to be particularly advantageous for use as lubricants for metalworking. They can thus be used as metalworking fluids, for various applications, as a substitute for conventionally used lubricants, in particular hydrocarbon lubricants.

[0030] The invention thus relates, according to another of its aspects, to the use of an aqueous lubricating composition according to the invention, as a lubricant in a metalworking process.

[0031] An aqueous composition according to the invention can be more particularly used as a lubricant in any metal machining operation, for example in processes of shaping, cutting, joining or any other transformation of the metal such as forming, stamping, rolling, etc.

[0032] It can be used for working various metals, such as aluminum, steel, galvanized steel or even yellow metals.

[0033] The invention also relates to a method for working metals using, as lubricant, an aqueous lubricating composition according to the invention. Said method comprises in particular a step of applying an aqueous lubricating composition according to the invention to the surface of at least one part of the machining tool (or apparatus) and / or a metal workpiece.

[0034] The lubricating fluid according to the invention advantageously makes it possible to reduce friction between the tool or machining equipment and the machined metal part.

[0035] The invention thus relates to the use of an aqueous lubricating composition according to the invention to reduce friction during a machining operation of a metal part.

[0036] Furthermore, advantageously, an aqueous lubricating composition leads to a low quantity of gummy residues, after its use in the equipment used for machining metals.

[0037] "Gummy residues" are relatively viscous and insoluble residues in the aqueous phase, which may appear after machining operations. More specifically, once the machining equipment is stopped, the lubricant, subject to ambient dehydration, is likely to lead to the formation of salts which, combined with the polymers present in the lubricant, can form these gummy residues.

[0038] Gummy residues adhere to the tool walls and can cause the machining tool to jam, usually requiring unwanted maintenance operations on the machine.

[0039] Finally, advantageously, a lubricating composition according to the invention, formed mainly of water, has little toxicological impact, particularly for people using this lubricant. Advantageously, even if water is the main solvent of an aqueous lubricant according to the invention, the treated surface is correctly lubricated.

[0040] In addition, the presence of a significant proportion of water makes it easier to clean metal surfaces and remove lubricant after machining, particularly by simply passing or rinsing with water.

[0041] Other characteristics, variants and advantages of an aqueous lubricating composition according to the invention will become more apparent upon reading the description and examples which follow, given by way of illustration and not limitation of the invention.

[0042] The expressions "between ... and ...", "ranging from ... to ...", "formed from ... to ...", and "varying from ... to ...", must be understood inclusively, unless otherwise stated.

[0043] In the description and examples, unless otherwise indicated, percentages are by weight. Percentages are therefore expressed by mass relative to the total mass of the composition. Temperature is expressed in degrees Celsius unless otherwise indicated, and pressure is atmospheric pressure unless otherwise indicated. Detailed description AQUEOUS COMPOSITION

[0044] As mentioned previously, an aqueous lubricating composition according to the invention, also called an aqueous lubricant, is a formulation comprising water as the major solvent.

[0045] For the purposes of the invention, the term "majority solvent" is understood to mean that water is present in a greater quantity than any other solvent possibly present in the composition. An aqueous lubricating composition according to the invention comprises at least 50% by mass of water, in particular osmosis water, preferably between 50% and 90% by mass, more preferably between 60% and 75% by mass, relative to the total mass of the composition.

[0046] By its role as a solvent, water makes it possible to solubilize the said polysaccharide(s), the castor oil and the phosphorus and / or sulfur anti-wear additive(s), as well as any additive optionally present in the composition, in particular chosen from those detailed in the rest of the text.

[0047] Advantageously, in addition to its role as a solvent, water provides access to a lubricating composition with good cooling properties, useful in the field of metal machining.

[0048] According to a particular embodiment, the water used in an aqueous lubricating composition according to the invention is deionized water or osmosis water.

[0049] Advantageously, deionized water does not include ions, such as the Ca 2+< and HCO 3 -< ions generally present in water, which are responsible for the conduction of electricity in water.

[0050] The use of deionized water is therefore particularly advantageous in the context of the use of the aqueous lubricant according to the invention for applications requiring a fluid that conducts little, or even no, electricity.

[0051] An aqueous lubricating composition according to the invention differs from hydrocarbon lubricants, which comprise a majority proportion of one or more base oils which are not soluble in water.

[0052] The term "water-insoluble oil" includes, in particular, an oil that does not dissolve substantially in water at room temperature (at about 25°C). In particular, a water-insoluble oil has a solubility in water of less than 0.2 g / L at room temperature.

[0053] These include lubricating base oils belonging to groups I to V according to the classes defined in the API classification (or their equivalents according to the ATIEL classification) and their mixtures.

[0054] Preferably, an aqueous lubricating composition according to the present invention comprises less than 20% by weight of water-insoluble base oil(s), preferably less than 10% by weight, in particular less than 5% by weight, relative to the total weight of the composition.

[0055] Advantageously, an aqueous lubricating composition according to the invention is completely free of oil which is not soluble in water. POLYSACCHARIDE

[0056] As indicated previously, an aqueous lubricating composition according to the invention comprises from 0.01% to 10% by mass of at least one polysaccharide.

[0057] It is understood that a lubricating composition according to the invention may comprise a single polysaccharide, or a mixture of at least two distinct polysaccharides, in particular as described below.

[0058] In the context of the present invention, the term "polysaccharides" means polymers consisting of several oses linked together by osidic bonds. More preferably, the polysaccharides targeted by the invention are celluloses and galactomannans, preferably guars, as well as their derivatives.

[0059] Preferably, the polysaccharides targeted by the invention have a molar mass of between 10 and 2000 kg / mol, preferably of between 100 and 1000 kg / mol.

[0060] The polysaccharide may, for example, be chosen from cellulose or one of its derivatives, in particular cellulose ethers or esters.

[0061] The polysaccharide can also be chosen from galactomannan polysaccharides.

[0062] Galactomannan polysaccharides are heterogeneous polysaccharides consisting of galactose and mannose units. These non-ionic polysaccharides can be extracted from the endosperm of legume seeds, where they constitute the reserve carbohydrate.

[0063] More specifically, they are macromolecules consisting of a main chain of D-mannopyranose units linked in β(1,4), carrying side branches consisting of a single D-galactopyranose unit linked in α(1,6) to the main chain. The different galactomannans are distinguished on the one hand by the proportion of α-D-galactopyranose units present in the polymer and, on the other hand, by differences in terms of distribution of the galactose units along the mannose chain.

[0064] The mannose / galactose (M / G) ratio is around 2 for guar gum, 3 for tara gum and 4 for locust bean gum.

[0065] Galactomannan polysaccharides can more specifically have the following chemical structure: with, for example, m being 1 (guar gum), 2 (tara gum) or 3 (locust bean gum).

[0066] The galactomannan polysaccharides may be chosen in particular from guar gum, carob gum, tara gum and their derivatives.

[0067] By “derivatives” we mean more specifically chemically modified non-ionic gums, or cationic or anionic gums.

[0068] According to a particular embodiment, a lubricating composition according to the invention comprises at least one galactomannan polysaccharide of guar gum type. The expression "of guar gum type" is intended to denote guar gum and its derivatives, in particular chosen from chemically modified non-ionic guar gums, cationic or anionic guar gums.

[0069] Guar gum is characterized by a mannose:galactose ratio of about 2:1. The galactose group is regularly distributed along the mannose chain.

[0070] It is understood that a lubricating composition according to the invention may comprise a single galactomannan polysaccharide, in particular of the guar gum type, or a mixture of at least two distinct galactomannan polysaccharides, for example a mixture of at least two galactomannan polysaccharides chosen from guar gum and its derivatives.

[0071] Guar gum-type galactomannan polysaccharides may be unmodified or chemically modified non-ionic guar gums.

[0072] The modified non-ionic guar gums that can be used according to the invention may more particularly be guar gums modified by C 1 -C 6 hydroxyalkyl groups, among which, as examples, mention may be made of hydroxymethyl, hydroxyethyl, hydroxypropyl and hydroxybutyl groups. By way of example, a chemically modified non-ionic guar gum used in a lubricating composition according to the invention may be hydroxypropyl guar.

[0073] Galactomannan polysaccharides, for example of the guar gum type, may also be cationic galactomannans, in particular having a cationic charge density of less than or equal to 1.5 meq / g and more particularly between 0.1 and 1 meq / g. The charge density can be determined according to the Kjeldahl method. It generally corresponds to a pH of the order of 3 to 9. Generally, a cationic galactomannan polysaccharide comprises cationic groups and / or groups that can be ionized into cationic groups.

[0074] The preferred cationic groups are chosen from those comprising primary, secondary, tertiary and / or quaternary amine groups.

[0075] Cationic galactomannan polysaccharides generally have a weight average molecular weight of between about 500 and 5x10 6<, and preferably between about 10 3< and 3x10 6<.

[0076] It may be, for example, a galactomannan polysaccharide comprising cationic trialkyl(C 1 - C 4 ) ammonium groups. Preferably, 2% to 30% by number of the hydroxyl functions of the galactomannan polysaccharide carry cationic trialkylammonium groups.

[0077] Among these trialkylammonium groups, we can particularly cite the trimethylammonium and triethylammonium groups.

[0078] Even more preferably, these groups represent from 5% to 20% by weight of the total weight of the modified galactomannan polysaccharide.

[0079] Guar gum-type galactomannan polysaccharides can thus be cationic guar gums, in particular those containing hydroxypropyltrimethylammonium groups. They can be obtained, for example, by reacting guar gum with 2,3-epoxypropyltrimethylammonium chloride.

[0080] For example, a cationic guar gum, used in a lubricating composition according to the invention, may be guar hydroxypropyl trimonium chloride.

[0081] Galactomannan polysaccharides, for example of the guar gum type, may also be anionic galactomannans. In particular, they may be galactomannan polysaccharides comprising groups derived from carboxylic, sulfonic, sulfenic, phosphoric, phosphonic or pyruvic acid. Preferably, the anionic group is a carboxylic acid group. The anionic group may also be in the form of an acid salt, in particular a sodium, calcium, lithium or potassium salt.

[0082] Guar gum-type galactomannan polysaccharides can thus be carboxymethylated guar gums, such as carboxymethyl guar or carboxymethyl hydroxypropyl guar.

[0083] For example, an anionic guar gum used in a lubricating composition according to the invention may be carboxymethyl hydroxypropyl guar.

[0084] Preferably, said galactomannan polysaccharide(s) used in a lubricating composition according to the invention are chosen from guar gum, guar gum derivatives, and mixtures thereof, in particular from guar gum, hydroxypropyl guar, carboxymethyl hydroxypropyl guar, guar hydroxypropyltrimonium chloride, and mixtures thereof.

[0085] According to a particular embodiment, a lubricating composition according to the invention uses, as galactomannan polysaccharide, at least hydroxypropyl guar.

[0086] An aqueous lubricating composition according to the invention comprises said polysaccharide(s) in a content of between 0.01% and 10% by mass, more preferably between 0.1% and 5% by mass, even more preferably between 0.1% and 3.5% by mass, in particular between 0.2% and 1% by mass, relative to the total mass of the composition. ALCOXYLATED CASTOR OIL

[0087] As indicated previously, an aqueous lubricating composition according to the invention comprises from 0.1% to 10% by mass of at least one alkoxylated, in particular ethoxylated, castor oil.

[0088] It is understood that a lubricating composition according to the invention may comprise a single alkoxylated castor oil, in particular ethoxylated, or a mixture of at least two distinct particular alkoxylated castor oils, in particular as described below.

[0089] Castor oil is composed of fatty acid triglycerides, predominantly C16 to C18 fatty acids. More specifically, ricinolein, a triglyceride of ricinoleic acid (C18 fatty acid), is the major constituent of castor oil.

[0090] Alkoxylated castor oil is formed from alkoxylated triglycerides.

[0091] Preferably, a lubricating composition according to the invention comprises an alkoxylated (C 1 -C 4 ) castor oil, preferably ethoxylated.

[0092] It can be obtained by alkoxylation of castor oil by an alkylene oxide, in particular C 1 to C 4 , or by transesterification by a polyalkylene glycol, in particular a poly(C 1 -C 4 )alkylene glycol.

[0093] Preferably, a lubricating composition according to the invention uses an ethoxylated castor oil. It can be obtained by ethoxylation of castor oil with ethylene oxide, or by transesterification of castor oil with a polyethylene glycol.

[0094] According to a particular embodiment, a lubricating composition according to the invention uses an ethoxylated castor oil, obtained by reaction of castor oil with ethylene oxide, in a molar ratio of castor oil:ethylene oxide of between 1:1 and 1:100.

[0095] An ethoxylated castor oil used in a lubricating composition according to the invention may in particular comprise at least 20 oxyethylene groups, preferably from 35 to 45 oxyethylene groups.

[0096] Preferably, it is an ethoxylated castor oil obtained by reaction of castor oil with ethylene oxide, in a molar ratio of castor oil:ethylene oxide of approximately 1:35, denoted “PEG-35-castor oil”.

[0097] As mentioned above, the alkoxylated castor oil, preferably ethoxylated, in particular as described above, is used in an amount of 0.1% to 10% by mass, relative to the total mass of the composition, in particular 1% to 10% by mass, and more particularly 2% to 5% by mass, relative to the total mass of the composition. PHOSPHORUS AND / OR SULFUR COMPOUND

[0098] As indicated above, an aqueous lubricating composition according to the invention comprises from 0.1% to 10% by mass of at least one sulfur and / or phosphorus anti-wear compound.

[0099] It is more particularly an organophosphorus and / or organosulfur anti-wear compound, preferably organosulfur.

[0100] For the purposes of the present invention, the term “phosphorus compound” means an anti-wear additive comprising at least one phosphorus atom.

[0101] For the purposes of the present invention, the term “sulfur compound” means an anti-wear additive comprising at least one sulfur atom.

[0102] For the purposes of the present invention, the term “phosphosulfur compound” means an anti-wear additive comprising at least one phosphorus atom and at least one sulfur atom.

[0103] For the purposes of the present invention, the term "anti-wear compound" is understood to mean a compound having anti-wear properties, which can in particular be evaluated by an extreme pressure 4-ball test, in particular according to standard ASTM D2783. Such compounds are well known to those skilled in the art.

[0104] It is understood that an aqueous lubricating composition according to the invention may comprise a single sulfur and / or phosphorus anti-wear compound or a mixture of at least two distinct sulfur and / or phosphorus anti-wear compounds, in particular as defined below. Phosphorus compounds

[0105] An aqueous lubricating composition according to the invention may comprise at least one phosphorus compound. In particular, the phosphorus compounds considered according to the invention do not provide sulfur.

[0106] Said phosphorus compound(s) are advantageously used in a form which is soluble or emulsifiable in water, in particular in the form of ionic salts.

[0107] In particular, the phosphorus compound may be chosen from amine phosphates; phosphates such as phosphate esters, in particular alkyl, alkenyl or aryl phosphates; polyphosphates; phosphonates such as phosphonate esters, in particular alkyl, alkenyl or aryl phosphonates; polyphosphonates; carbamyl phosphates; phosphinates; and mixtures thereof.

[0108] The phosphorus compound(s) are preferably present in an aqueous lubricating composition according to the invention in the form of salts, in particular in the form of phosphate, phosphonate or phosphinate ions, neutralized by a suitable counterion.

[0109] The salts may be salts of alkali or alkaline earth metals, ammonium, alkanolamines, in particular C 2 -C 8 , or alkane amines, in particular C 2 -C 8 , phosphate, phosphonate or phosphinate.

[0110] Examples of compounds particularly suitable for the invention are phosphate esters, phosphonate esters and their salts, preferably phosphate esters and their salts.

[0111] Phosphate esters, also called phosphoric acid esters, can be obtained by reaction of at least one alcohol, linear or branched, ethoxylated or not, preferably of at least one alcohol comprising between 1 and 12 carbon atoms, more preferably between 2 and 8 carbon atoms, with phosphorus pentoxide of formula P 2 0 5 or with phosphoric acid.

[0112] Preferably, a phosphorus compound used in an aqueous composition according to the invention is chosen from phosphate ester salts, in particular alkali metal salts of phosphate esters, in particular C 1 -C 8 alkyl or dialkyl phosphate esters.

[0113] Such a compound may in particular be chosen from potassium butylphosphate, potassium dibutylphosphate and mixtures thereof. Sulfur compounds

[0114] According to another particular embodiment, an aqueous lubricating composition according to the invention may comprise at least one sulfur compound, in particular not providing phosphorus.

[0115] The sulfur anti-wear compounds may in particular be chosen from polysulfides, in particular sulfur olefins, sulfur fatty acids, sulfur fatty acid esters, preferably used in their neutralized form, emulsifiable in water. Advantageously, an aqueous lubricating composition according to the invention comprises at least one organosulfur compound of the sulfur fatty acid type, preferably in a neutralized form, in particular by inorganic alkalizing agents or alkanolamines.

[0116] Sulfur-containing fatty acids may comprise from 8 to 22 carbon atoms, preferably from 12 to 18 carbon atoms.

[0117] The quantity of sulfur according to ASTM D2622 standard provided by said sulfur-containing fatty acid(s) may be between 5% and 30% by mass, in particular between 10% and 20% by mass.

[0118] Preferably, the quantity of active sulfur at 150°C according to standard ASTM D 1662 provided by said sulfur-containing fatty acid(s) in the aqueous lubricating composition according to the invention is greater than or equal to 2% by mass, in particular between 5 and 10% by mass, relative to the total mass of the lubricating composition.

[0119] For the purposes of the present invention, "active sulfur" means the sulfur that a chemical compound is capable of yielding or releasing when this compound is placed under the conditions of ASTM D1662. ASTM D-1662 defines an active sulfur level of a compound at a given temperature as a difference expressed as a weight percentage of sulfur content before and after reaction of a sample of this sulfur compound with a given quantity of copper for a fixed time.

[0120] The amount of active sulfur at 150°C (ASTM D1662 standard) in the aqueous lubricating composition of the invention can influence its extreme pressure performance. This amount of active sulfur at 150°C (ASTM D1662) in the lubricating composition must not be too low, otherwise satisfactory extreme pressure behavior cannot be obtained. It must not be too high, to avoid a risk of corrosion, in particular with respect to metals and metal alloys, in particular with respect to copper.

[0121] As mentioned above, said sulfur-containing fatty acid(s) are preferably used in an aqueous lubricating composition according to the invention in their form neutralized by an alkalizing agent, such as sodium hydroxide, potassium hydroxide, or an alkanolamine, such as monoethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine and triisopropanolamine. Phosphosulfur compounds

[0122] Examples of phosphosulfur compounds suitable for the invention are more particularly thiophosphates, in particular metal alkylthiophosphates, thiophosphites, including thiophosphoric and thiophosphorous acids, esters of these acids, their salts, dithiophosphites and dithiophosphates.

[0123] Examples of such compounds include amine dithiophosphates, monobutylthiophosphate, monooctylthiophosphate, monolaurylthiophosphate, dibutylthiophosphate, dilaurylthiophosphate, tributylthiophosphate, trioctylthiophosphate, triphenylthiophosphate, trilaurylthiophosphate, monobutylthiophosphite, monooctylthiophosphite, monolaurylthiophosphite, dibutylthiophosphite, dilaurylthiophosphite, tributylthiophosphite, trioctylthiophosphite, triphenylthiophosphite, trilaurylthiophosphite and salts thereof.

[0124] Examples of salts of the esters of thiophosphoric acid and thiophosphorous acid are those obtained by reaction with a nitrogenous compound such as ammonia or an amine or zinc oxide or zinc chloride.

[0125] Preferably, a lubricating composition according to the invention uses one or more sulfur-containing or phosphorus-containing anti-wear compounds, preferably sulfur-containing, in particular as defined above and more particularly chosen from sulfur-containing fatty acids comprising from 8 to 22 carbon atoms, preferably from 12 to 18 carbon atoms, preferably in a neutralized form, in particular by inorganic alkalizing agents or alkanolamines.

[0126] Said sulfur and / or phosphorus anti-wear compound(s), preferably sulfur, are used in an aqueous lubricating composition according to the invention in an amount of 0.1% to 10% by mass, preferably 0.1% to 5.0% by mass, more preferably 0.5% to 3.0% by mass, relative to the total mass of the composition.

[0127] According to a particular embodiment, a lubricating composition according to the invention may comprise said sulfur and / or phosphorus anti-wear agent(s), preferably sulfur, and one or more castor oils, preferably an ethoxylated castor oil, in a mass ratio of anti-wear agent(s): castor oil(s) of between 1:1 and 10:1, in particular approximately 1:1. OTHER COMPOUNDS Polyalkylene glycol

[0128] As indicated previously, an aqueous lubricating composition according to the invention preferably further comprises at least one polyalkylene glycol.

[0129] Polyalkylene glycols (denoted “PAG”) are homo- or co-polymers made up of alkylene oxide units.

[0130] They are particularly chosen from water-soluble polyalkylene glycols.

[0131] By "water soluble" is meant a polyalkylene glycol having a water solubility of at least 10 g / L, preferably at least 500 g / L, in water at room temperature (about 25°C).

[0132] The polyalkylene glycols may more particularly be formed from C 1 -C 4 alkylene oxide units, preferably C 1 -C 3 , more particularly C 2 -C 3 .

[0133] Advantageously, a polyalkylene glycol used in an aqueous lubricating composition according to the invention comprises at least 50% by mass of propylene oxide and / or ethylene oxide units.

[0134] It may be a copolymer, in particular a random copolymer, comprising ethylene oxide, propylene oxide and / or butylene oxide units. Preferably, it may be a copolymer, in particular a random copolymer, of ethylene oxide / propylene oxide.

[0135] Preferably, a polyalkylene glycol used in an aqueous lubricating composition according to the invention has a mass average molar mass (Mn) of between 100 and 25,000 g.mol -1< , preferably between 5,000 and 21,000 g.mol -1< .

[0136] The number-average molar mass can be measured by gel permeation chromatography (GPC).

[0137] Preferably, a polyalkylene glycol used in an aqueous lubricating composition according to the invention has a kinematic viscosity measured at 100°C (KV100), according to standard ASTM D445, of between 100 and 5,000 mm 2 < / s, in particular between 150 and 3,000 mm 2 < / s, for example between 1,500 and 3,000 mm 2 < / s or between 100 and 250 mm 2 < / s.

[0138] Preferably, a polyalkylene glycol used in an aqueous lubricating composition according to the invention has a kinematic viscosity measured at 40°C (KV40), according to standard ASTM D445, of between 500 and 30,000 mm 2 < / s, more particularly between 1,000 and 25,000 mm 2 < / s, for example between 10,000 and 25,000 mm 2 < / s or between 500 and 2,500 mm 2 < / .

[0139] The flash point of a polyalkylene glycol used in an aqueous lubricating composition according to the invention is preferably greater than or equal to 160°C, in particular greater than or equal to 220°C, for example between 220°C and 300°C. The flash point can be measured by the ISO 2592 or ASTM D92 standard.

[0140] Preferably, a polyalkylene glycol used in an aqueous lubricating composition according to the invention has a viscosity index measured according to standard ASTM D2270, between 100 and 800, preferably between 250 and 550.

[0141] Such polyalkylene glycols may be commercially available or synthesized according to methods known to those skilled in the art. They may be obtained, for example, by polymerization or copolymerization of alkylene oxides having between 2 and 4 carbon atoms. An example of synthesis is, for example, detailed in document US 2012 / 0108482, by reaction between one or more alcohols having between 2 and 12 carbon atoms, in particular polyols, such as diols, with alkylene oxides, in particular ethylene oxide, propylene oxide and / or butylene oxide. The alcohol may preferably be a diol, in particular 1,2-propanediol.

[0142] In particular, said polyalkylene glycol compound(s) may be used in an aqueous lubricating composition according to the invention in a content of between 0.001% and 80% by mass, preferably between 0.1% and 15% by mass, more preferably between 1% and 10% by mass, in particular between 2% and 5% by mass, relative to the total mass of the composition. Additives

[0143] An aqueous lubricating composition according to the invention may further comprise various additives.

[0144] It is understood that the said additive(s) are compatible with their implementation in an aqueous medium. Advantageously, the additives are implemented in a form that is soluble or emulsifiable in water, for example in the form of salts or ionic liquids.

[0145] The said additive(s) are of course chosen with regard to the intended application for the aqueous lubricant.

[0146] Of course, the person skilled in the art will take care to choose the possible additives and / or their quantity in such a way that the advantageous properties of the aqueous lubricating composition according to the invention, in particular the advantageous effect of improving the tribological properties, in particular the extreme pressure properties and protection of the parts against wear, are not altered by the envisaged addition.

[0147] Such additives may be more particularly chosen from anti-foaming agents, biocides, pH regulators, corrosion inhibitors, anti-wear and / or extreme pressure additives other than the aforementioned sulfur and / or phosphorus compounds, sequestering agents, metal passivating agents, colorants, dispersants, emulsifying agents, wetting agents, and mixtures thereof.

[0148] Advantageously, an aqueous lubricating composition according to the invention may comprise one or more additives chosen from anti-foaming agents, biocides, pH regulators, corrosion inhibitors, sequestering agents, metal passivating agents, emulsifying agents and mixtures thereof.

[0149] An aqueous lubricating composition according to the invention may more particularly comprise from 1 to 50% by mass of additives, in particular from 5 to 40% by mass of additives, relative to the total mass of the composition. Corrosion inhibitor

[0150] An aqueous lubricating composition according to the invention may comprise at least one corrosion inhibiting agent. Corrosion inhibitors advantageously make it possible to reduce or even prevent the corrosion of metal parts. The nature of said corrosion inhibitor(s) may be chosen with regard to the metal to be protected against corrosion, such as aluminum, steel, galvanized steel, yellow metals, for example copper or brass. Among the inorganic corrosion inhibitors that may be mentioned are nitrites, sulfites, silicates, borates, sodium, potassium, calcium or magnesium phosphates, alkali metal phosphates, hydroxides, molybdates, zinc, magnesium or nickel sulfates.

[0151] Among the organic corrosion inhibitors that may be mentioned are aliphatic monocarboxylic acids, in particular having from 4 to 15 carbon atoms, for example octanoic acid, aliphatic dicarboxylic acids having from 4 to 15 carbon atoms, for example decanedioic acid (sebacic acid), undecanedioic acid, dodecanedioic acid, isononanoic acid or mixtures thereof, polycarboxylic acids optionally neutralized by triethanolamine, such as 1,3,5-triazine-2,4,6-tri-(6-aminocaproic acid), alkanoylamidocarboxylic acids, in particular isononanoylamidocaproic acid, 6-[[(4-methylphenyl)sulfonyl]amino]hexanoic acid, and mixtures thereof. Borated amides, products of the reaction of amines or amino alcohols with boric acid, can also be used.

[0152] An aqueous lubricating composition according to the invention may in particular comprise from 0.01% to 15% by mass of corrosion inhibitor(s), preferably from 1.0% to 13% by mass, relative to the total mass of the composition. Anti-foam

[0153] An aqueous lubricating composition according to the invention may comprise at least one antifoam additive. Antifoams make it possible to prevent foaming of the lubricating fluid.

[0154] This may be, for example, an anti-foaming agent based on polysiloxanes or acrylate polymers. Preferably, the anti-foaming agent is chosen from three-dimensional siloxanes.

[0155] Also, antifoam agents can be polar polymers such as polymethylsiloxanes or polyacrylates.

[0156] In particular, an aqueous lubricating composition according to the invention may comprise from 0.001% to 3.0% by mass of anti-foam additive(s), preferably from 0.005% to 1.5% by mass, relative to the total mass of the lubricating composition. pH regulator

[0157] An aqueous lubricating composition according to the invention may comprise at least one pH regulating additive, in particular an alkaline buffer. The pH regulator makes it possible to maintain the desired pH of the lubricating composition, in particular in order to preserve an alkaline pH, advantageously between 8 and 11, in particular so as to prevent corrosion of metal surfaces.

[0158] The pH regulator can be chosen from the amine family, in particular alkanolamines and amino alcohols.

[0159] This may include, in particular, a pH regulating additive selected from ethanolamines, such as monoethanolamine (MEA), diethanolamine (DEA); triethanolamine (TEA), diglycolamine (DGA); isopropanolamines, such as monoisopropanolamine (MIPA), diisopropanolamine (DIPA) and triisopropanolamine (TIPA), ethylene amines, such as ethylene diamine (EDA), diethylene triamine (DETA), triethylene tetramine (TETA) and tetraethylene pentamine (TEPA), alkanolamines, such as methyldiethanolamine (MDEA), cyclamines, such as cyclohexylamine, 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1-propanol and mixtures thereof.

[0160] An aqueous lubricating composition according to the invention may in particular comprise from 1% to 25% by mass of pH regulating additive(s), preferably from 5% to 20% by mass, relative to the total mass of the composition. Metal passivating agents

[0161] An aqueous lubricating composition according to the invention may comprise at least one metal passivating agent. Metal passivating agents make it possible to protect metal parts by promoting the formation of metal oxide on their surface.

[0162] The metal passivating agents may be, for example, selected from triazole derivatives, such as tetrahydrobenzotriazole (THBTZ), tolyltriazole (TTZ), benzotriazole (BTZ), triazole-substituted amines, such as N,N-bis(2-ethylhexyl)-1,2,4-triazol-1-yl methanamine, N'-bis(2 ethylhexyl)-4-methyl-1H-benzotriazol-1-methyl-amine, N,N-bis(heptyl)-ar-methyl-1H-benzotriazol-1-methanamine, N,N-bis(nonyl)-ar-methyl-1H-benzotriazol-1-methanamine, N,N-bis(decyl)-ar-methyl-1H-benzotriazol-1-methanamine, N,N-bis(undecyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(dodecyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine, 1,2,4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles, 2-alkyldithiobenzothiazoles, 2-(N,N-dialkyldithiocarbamoyl)benzothiazoles, 2,5-bis(alkyldithio)-1,3,4-thiadiazoles, such as 2,5-bis(tert-octyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-decyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-undecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-dodecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-tridecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-tetradecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-pentadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-hexadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-heptadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-octadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-nonadecyldithio)-1,3,4-thiadiazole, 2,5-bis(tert-eicosyldithio)-1,3,4-thiadiazole, 2,5-bis(N,N-dialkyldithiocarbamoyl)-1,3,4-thiadiazoles, 2-alkyldithio-5-mercaptothiadiazoles, and mixtures thereof.

[0163] Preferably, the metal passivating agents are chosen from tetrahydrobenzotriazole (THBTZ), tolyltriazole (TTZ), benzotriazole (BTZ), and their salts, taken alone or in mixtures.

[0164] An aqueous lubricating composition according to the invention may in particular comprise from 0.01% to 2.0% by mass of metal passivating agent(s), preferably from 0.1% to 1.0% by mass, more preferably from 0.2% to 0.8% by mass, relative to the total mass of the composition. Dyes

[0165] An aqueous lubricating composition according to the invention may comprise one or more colorants. The colorants may be natural or synthetic, generally organic. The colorants that may be used in an aqueous lubricating composition may be more particularly chosen from natural or synthetic water-soluble colorants, for example the colorants FDC Red 4, DC Red 6, DC Red 22, DC Red 28, DC Red 30, DC Red 33, DC Orange 4, DC Yellow 5, DC Yellow 6, DC Yellow 8, FDC Green 3, DC Green 5, FDC Blue 1, betanin (beetroot), carmine, a chlorophyllin, methylene blue, anthocyanins (enocyanin, black carrot and hibiscus), caramel and riboflavin.

[0166] An aqueous lubricating composition according to the invention may comprise between 0.01% and 2.0% by mass of colorant(s), preferably between 0.01% and 1.5% by mass, more preferably between 0.02% and 1.0% by mass, relative to the total mass of the composition. Emulsifying agents

[0167] An aqueous lubricating composition according to the invention may comprise one or more emulsifying agents, also called emulsifiers. Their function is to generate stable emulsions in water.

[0168] The emulsifying agents may be more particularly non-ionic, such as for example ethoxylated fatty alcohols, ethoxylated fatty acids, compounds resulting from the reaction between propylene oxide, ethylenediamine and possibly ethylene oxide of ethoxylated fatty amides; anionic, for example KOH, NaOH soaps; sulphonates; cationic, such as quaternary ammonium compounds; or even carboxylic acid esters which are soluble or emulsifiable in water.

[0169] In particular, an aqueous lubricating composition according to the invention may comprise from 0.01% to 10% by mass of emulsifying agent(s), preferably from 0.1% to 5.0% by mass, relative to the total mass of the lubricating composition. Sequestering agents

[0170] An aqueous lubricating composition according to the invention may comprise at least one sequestering agent. Sequestering agents, also called chelating agents, make it possible to limit the encrustation of metal ions in the composition.

[0171] Examples of sequestering agents include those derived from phosphonic acids and phosphonates, such as diethylenetriaminepentamethylphosphonic acid (DTPMPA), aminotri(methylenephosphonic acid) (ATMP), hydroxyethanediphosphonic acid (HEDP), 1-hydroxyethylidene 1,1-diphosphonate, 2-hydroxyethylaminedi(methylenephosphonic acid) (HEAMBP), diethylenetriaminopenta(methylenephosphonic acid) (DTMP), multifunctional organic acids and hydroxy acids, such as ethylenediaminetetraacetic acid (EDTA), pteroyl-L-glutamic acid (PGLU), organic polyacids, such as maleic acid and polyaspartic acid and carbohydrates, such as inulin, carboxymethylinulin and carboxymethylchitosan.

[0172] An aqueous lubricating composition according to the invention may comprise from 0.001% to 2.0% by mass of sequestering agent(s), preferably from 0.01% to 1.0% by mass, relative to the total mass of the composition. Biocides

[0173] An aqueous lubricating composition according to the invention may comprise at least one biocidal agent with bactericidal and / or fungicidal action. The biocides may be used to improve the biological stability of the composition by limiting the proliferation of bacteria, fungi and yeasts in the lubricating fluid.

[0174] Such biocides may be selected from parabens, aldehydes, reactive acetylacetone compounds, isothiazolinones, phenolic compounds, acid salts, halogenated compounds, quaternary ammoniums, certain alcohols and mixtures thereof.

[0175] Preferably, the biocides may be chosen from optionally substituted benzisothiazolinones (BIT), such as N-butyl-1,2-benzisothiazolin-3-one, methylisothiazolinones (MIT), mixtures of methylisothiazolinone and chloromethylisothiazolinone (MIT / CMIT), orthophenyl-phenol (OPP) or its sodium salt, 3-iodo-2-propynylbutylcarbamate (IPBC), chloro-cresol and N,N-methylene-bis-morpholine (MBM); sorbic acid; preferably from orthophenyl-phenol (OPP) or its sodium salt, 3-iodo-2-propynylbutylcarbamate, chloro-cresol, benzisothiazolinones and N,N-methylene-isomorpholine.

[0176] An aqueous lubricating composition according to the invention may in particular comprise between 0.01% and 10% by mass of biocide(s), preferably between 0.1% and 5.0% by mass, relative to the total mass of the composition.

[0177] According to a particular embodiment, an aqueous lubricating composition according to the invention comprises: at least 50% by mass of water, preferably osmosis water; from 0.01% to 10% by mass of at least one polysaccharide, in particular as defined above, in particular a galactomannan polysaccharide and more particularly of guar gum type; from 0.1% to 10% by mass of at least one alkoxylated, in particular ethoxylated, castor oil; from 0.1% to 10% by mass of at least one phosphorus and / or sulfur anti-wear compound, in particular sulfur; and optionally from 1% to 50% by mass, in particular from 5 to 40% by mass, of one or more additives chosen from anti-foaming agents, biocides, pH regulators, corrosion inhibitors, sequestering agents, metal passivating agents, emulsifying agents, and mixtures thereof, the contents being expressed in relation to the total mass of the lubricating composition.

[0178] Preferably, an aqueous lubricating composition according to the invention comprises: at least 50% by mass of water, preferably osmosis water; from 0.01% to 10% by mass of at least one polysaccharide, in particular as defined above, in particular a galactomannan polysaccharide and more particularly of guar gum type; from 0.1% to 10% by mass of at least one alkoxylated, in particular ethoxylated, castor oil; from 0.1% to 10% by mass of at least one phosphorus and / or sulfur anti-wear compound, in particular sulfur; from 0.001% to 30% by mass, preferably from 0.1% to 15% by mass, of at least one polyalkylene glycol, in particular as defined above; and optionally from 1% to 50% by mass, in particular from 5 to 40% by mass, of one or more additives chosen from anti-foaming agents, biocides, pH regulators, corrosion inhibitors, sequestering agents, metal passivating agents, emulsifying agents, and mixtures thereof, the contents being expressed in relation to the total mass of the lubricating composition.

[0179] In particular, an aqueous lubricating composition according to the invention may consist of: from 0.01% to 10% by mass of at least one polysaccharide, in particular as defined above, in particular a galactomannan polysaccharide and more particularly of guar gum type; from 0.1% to 10% by mass of at least one alkoxylated, in particular ethoxylated, castor oil; from 0.1% to 10% by mass of at least one phosphorus and / or sulfur anti-wear compound, in particular sulfur; from 0.001% to 30% by mass of at least one polyalkylene glycol, preferably from 0.1% to 15% by mass, in particular as defined above; and optionally from 1% to 50% by mass, in particular from 5 to 40% by mass, of one or more additives chosen from anti-foaming agents, biocides, pH regulators, corrosion inhibitors, sequestering agents, metal passivating agents, emulsifying agents, and mixtures thereof, the contents being expressed relative to the total mass of the lubricating composition, and the remainder being made up of water, preferably osmosis water.

[0180] According to the invention, the particular, advantageous or preferred characteristics of the composition according to the invention make it possible to define uses according to the invention which are also particular, advantageous or preferred.

[0181] The invention will now be described by means of the following examples given of course for illustrative and non-limiting purposes of the invention. Example Measurement of tribological properties

[0182] The extreme pressure and anti-wear properties of the lubricating compositions are evaluated by the 4-ball test according to the ASTM D2783 standard adapted with the following parameters: speed close to 1500 rpm, room temperature, approximately 20°C, charging time of 1 minute.

[0183] The extreme pressure measurement is carried out by rotating a stainless steel ball on three stainless steel balls held stationary, the 4 balls being entirely covered with a film of lubricant. A load is applied to the balls and gradually increased (every minute according to the above parameters) until the balls weld together. The balls are changed before each increase in load.

[0184] Extreme pressure power corresponds to the load value at which the 4 balls weld together, preventing the rotation of the upper ball on the other 3. The greater the load, the higher the extreme pressure power.

[0185] This method also allows the anti-wear properties of a lubricating composition to be assessed. During the gradual increase in load, it is possible to determine, at each stage, the wear diameter on the 3 balls. The smaller the wear diameter, the more effective the lubricant is at preventing wear (or seizure) of the parts.

[0186] The wear diameter values ​​provided in the following examples are those obtained for the load value preceding ball welding.

[0187] It is common practice to dilute compositions before carrying out load tests, and the dilution rate is therefore specified in the results below. Example 1 : Preparation of lubricating compositions

[0188] An aqueous lubricating composition according to the invention (I1), and three comparative aqueous lubricating compositions, C1 not including phosphorus and / or sulfur compounds, C2not including alkoxylated castor oil, C3 not including alkoxylated castor oil or phosphorus and / or sulfur compounds, were formulated according to the protocol below, in the mass percentages indicated in Table 1 below.

[0189] The formulation protocol is as follows: The polysaccharide and possibly the alkoxylated castor oil are dissolved in reverse osmosis water. The solution is stirred for 30 minutes at room temperature (around 20°C).

[0190] Then, the other components are added as follows: introduction of the pH regulating additive(s), then the corrosion inhibiting additive(s) by heating the mixture to a temperature of 40 to 50°C. The solution is stirred using a magnetic bar for a period ranging from 1 hour to 1 hour 30 minutes. The following compounds are then added, sequentially every 5 minutes, in the following order and always with stirring: passivator(s), sequestering agent(s), PAG, the anti-wear additive(s) and then possibly wetting agent(s), antifoaming agent(s) and biocide(s).

[0191] Finally, a final stirring is carried out for 1 hour. [Table 1] Composition I1 according to the invention C1 excluding invention C2 outside invention C3 outside invention Osmosis water [%] 63,01 65,01 65,01 67,01 Polysaccharide 1 [%] (Hydroxyethyl cellulose) 0,40 0,40 0,40 0,40 Ethoxylated castor oil [%] (PEG-35 castor oil) 2 2 - - Sulfur anti-wear [%] (Sulfur fatty acid) 2 - 2 - Additive(s) (1)< 32,59 32,59 32,59 32,59 (1)< The additive(s) are chosen from anti-corrosion agents, passivators, sequestering agents, pH regulators, anti-foam agents and biocides. Example 2 : Characterization of the compositions according to the invention and comparison

[0192] Tribological properties were measured for each composition as detailed in the protocol above.

[0193] The results are compiled in Table 2 below. [Table 2] Composition Dilution rate [%] Welding load [kg] Wear diameter [mm] I1 (invention) 12 260 1,5 - 1,6 C1 (comparative) 12 220 1,6 - 1,7 C2 (comparative) 12 200 1,5 - 1,6 C3 (comparative) 12 180 1,7 - 1,8

[0194] Composition I1 according to the invention has a weld load significantly higher than that obtained for comparative compositions C1 to C3 and an equivalent, or even lower, wear diameter.

[0195] Thus, the lubricating compositions in accordance with the invention, incorporating a combination of at least one phosphorus and / or sulfur anti-wear compound and an alkoxylated, in particular ethoxylated, castor oil, have significantly improved extreme pressure properties, compared to compositions not comprising one or other of these compounds. Example 3 : Preparation of lubricating compositions

[0196] An aqueous lubricating composition according to the invention (I2), and three comparative aqueous lubricating compositions,C4 not including phosphorus and / or sulfur compounds, C5 not including alkoxylated castor oil, C6 not comprising alkoxylated castor oil or phosphorus and / or sulfur compounds, were formulated according to the same formulation protocol as described in example 1, with the mass percentages indicated in the following table 3. [Table 3] Composition I2 according to the invention C4 outside invention C5 outside invention C6 outside invention Osmosis water [%] 63,61 65,61 65,61 67,61 Polysaccharide 2 [%] (Hydroxypropyl Guar) 0,40 0,40 0,40 0,40 Ethoxylated castor oil [%] (PEG-35 castor oil) 2 2 - - Sulfur compound [%] (Sulfur fatty acid) 2 - 2 - Additive(s) (1)< 31,99 31,99 31,99 31,99 (1)< The additive(s) are chosen from anti-corrosion agents, passivators, sequestering agents, pH regulators, anti-foam agents and biocides. Example 4 : Characterization of the compositions according to the invention and comparison

[0197] Tribological properties were measured for each composition as detailed in the protocol above.

[0198] The results are compiled in Table 4 below. [Table 4] Composition Dilution rate [%] Welding load [kg] Wear diameter [mm] I2 (invention) 12 220 1,4 - 1,5 C4 (comparative) 12 180 1,7 - 1,8 C5 (comparative) 12 220 1,6 - 1,7 C6 (comparative) 12 180 1,6 - 1,7

[0199] Composition I2 according to the invention has a weld load equivalent to, or even superior to, those obtained for comparative compositions C4 to C6 and a lower wear diameter under extreme pressure conditions.

[0200] Thus, the lubricating compositions in accordance with the invention, incorporating a combination of at least one phosphorus and / or sulfur anti-wear compound and an alkoxylated, in particular ethoxylated, castor oil, have significantly improved extreme pressure properties, compared to compositions not comprising one or other of these compounds.

Claims

1. Aqueous lubricating composition, in particular for metalworking, comprising at least: - at least 50% by weight of water, preferably of osmosed water; - from 0.01% to 10% by weight of at least one polysaccharide; - from 0.1% to 10% by weight of at least one alkoxylated, in particular ethoxylated, castor oil; and - from 0.1% to 10% by weight of at least one sulfur-containing and / or phosphorus-containing antiwear compound, the percentages being expressed with respect to the total weight of the composition.

2. Aqueous lubricating composition according to Claim 1, comprising between 50% and 90% by weight of water, in particular of osmosed water, preferably between 60% and 75% by weight, with respect to the total weight of the composition.

3. Aqueous lubricating composition according to Claim 1 or 2, in which the alkoxylated castor oil is an ethoxylated castor oil, obtained by reaction of castor oil with ethylene oxide, in a castor oil:ethylene oxide molar ratio of between 1:1 and 1:100 and in particular of 1:35.

4. Aqueous lubricating composition according to any one of the preceding claims, comprising from 1% to 10% by weight of alkoxylated castor oil(s), more particularly from 2% to 5% by weight, with respect to the total weight of the composition.

5. Aqueous lubricating composition according to any one of the preceding claims, comprising from 0.1% to 5% by weight of polysaccharide(s), in particular from 0.1% to 3.5% by weight and more particularly from 0.2% to 1% by weight, with respect to the total weight of the composition.

6. Aqueous lubricating composition according to any one of the preceding claims, in which said sulfur- and / or phosphorus-containing antiwear compound(s) are chosen from organosulfur compounds of sulfur-containing fatty acid type comprising from 8 to 22 carbon atoms, preferably from 12 to 18 carbon atoms, preferably in a neutralized form, in particular a form neutralized with inorganic basifying agents or alkanolamines.

7. Aqueous lubricating composition according to any one of the preceding claims, comprising from 0.1% to 5% by weight of phosphorus- and / or sulfur-containing, preferably sulfur-containing, antiwear compound(s), more particularly from 0.5% to 3.0% by weight, with respect to the total weight of the composition.

8. Aqueous lubricating composition according to any one of the preceding claims, said composition additionally comprising at least one polyalkylene glycol, in particular chosen from copolymers, in particular random copolymers, comprising ethylene oxide, propylene oxide and / or butylene oxide units.

9. Aqueous lubricating composition according to the preceding claim, comprising from 0.001% to 80% by weight of polyalkylene glycol(s), preferably from 0.1% to 15% by weight, more preferentially from 1% to 10% by weight, in particular from 2% to 5% by weight, of polyalkylene glycol(s), with respect to the total weight of the composition.

10. Aqueous lubricating composition according to any one of the preceding claims, additionally comprising at least one additive chosen from antifoaming agents, biocides, pH regulators, corrosion inhibitors, sequestering agents, metal passivating agents, emulsifying agents and their mixtures.

11. Use of an aqueous lubricating composition as defined according to any one of the preceding claims as lubricant in a metalworking process.

12. Use of the combination of at least one alkoxylated, in particular ethoxylated, castor oil and of at least one phosphorus-containing and / or sulfur-containing, in particular sulfur-containing, antiwear compound in an aqueous lubricating composition comprising at least one polysaccharide, in order to improve its antiwear and / or extreme-pressure properties.