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 equipment 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 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 or 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] Document EP 3 124 583 A1 relates to a water-soluble metalworking fluid having excellent lubrication and wear resistance properties, even under severe machining conditions.

[0016] Unfortunately, the use of aqueous lubricants for metalworking applications has a major disadvantage related to the formation of so-called "gummy residues".

[0017] These gummy residues appear after machining operations. 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 relatively viscous and insoluble residues in the aqueous phase, referred to as "gummy residues".

[0018] Gummy residues adhere to the tool walls and can cause the machining tool to jam, usually requiring unwanted maintenance operations on the machine.

[0019] Thus, there remains a need for an aqueous lubricating composition for metalworking that produces little or no gummy residue, while maintaining, or even improving, the tribological properties of the lubricant, particularly in terms of anti-wear and extreme pressure properties.

[0020] The present invention aims precisely to meet this need. Statement of the invention

[0021] The present invention thus provides a new aqueous lubricating composition having tribological properties, in particular extreme pressure and anti-wear, suitable for its use in metalworking, and leading to low formation, or even the absence, of gummy residues after its use in machining equipment.

[0022] 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 0.1% to 15% by mass of at least one water-soluble polyalkylene glycol; and from 0.1% to 15% by mass of at least one alkoxylated, preferably ethoxylated, castor oil, the percentages being expressed relative to the total mass of the composition.

[0023] In particular, water-soluble polyalkylene glycol and / or alkoxylated, preferably ethoxylated, castor oil are not used as emulsifiers.

[0024] 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.

[0025] In the remainder of the text, the term “aqueous lubricating composition” or “aqueous lubricant” will refer to a water-based lubricating composition according to the invention.

[0026] 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.

[0027] Against all expectations, the inventors have discovered that the combined use of at least one polyalkylene glycol and at least one alkoxylated, in particular ethoxylated, castor oil provides access to an aqueous fluid with excellent tribological properties, suitable for use as a lubricant for metalworking, while leading to very low formation of gummy residues after use.

[0028] Thus, as illustrated in the examples which follow, it is possible, by supplementing an aqueous formulation, by the association of at least one polyalkylene glycol and at least one alkoxylated, in particular ethoxylated, castor oil, to access a lubricating fluid leading to a significantly reduced formation of gummy residues.

[0029] The combination of at least one polyalkylene glycol and an alkoxylated, in particular ethoxylated, castor oil in an aqueous lubricating composition more particularly has a synergistic effect on reducing the formation of gummy residues after use, while not impacting, or even improving, the anti-wear and extreme pressure properties of the aqueous lubricant.

[0030] The propensity of a lubricant formulation to form gummy residues can be assessed as described in the following examples.

[0031] The use of the combination of at least one polyalkylene glycol and at least one alkoxylated, in particular ethoxylated, castor oil in an aqueous lubricating composition is thus described, to reduce its propensity to form gummy residues after its use as a lubricant for metalworking.

[0032] The invention thus relates to the use of the combination of at least one water-soluble polyalkylene glycol and at least one alkoxylated, in particular ethoxylated, castor oil in an aqueous lubricating composition, to reduce its propensity to form gummy residues after its use as a lubricant for metalworking.

[0033] Furthermore, the combination of at least one polyalkylene glycol and at least one alkoxylated castor oil does not impact the tribological properties of the lubricating formulation, in particular the friction reduction performance, under extreme pressure conditions.

[0034] The aqueous lubricating composition according to the invention thus has good anti-wear and extreme pressure properties, or even, surprisingly, improved anti-wear and / or extreme pressure properties compared to a composition not comprising alkoxylated castor oil or polyalkylene glycol according to the invention.

[0035] 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 makes it possible to achieve high weld load values, without a significant increase in the wear diameter, which demonstrates its excellent tribological properties.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] It can be used for working various metals, such as aluminum, steel, galvanized steel or even yellow metals.

[0040] 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.

[0041] 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.

[0042] The present invention also relates to the use of an aqueous lubricating composition according to the invention to reduce, or even prevent (avoid), the formation of gummy residues after a metal machining operation using said composition as a lubricating fluid.

[0043] It relates more particularly to the use of an aqueous lubricating composition according to the invention to reduce friction during a metal machining operation, in particular friction between the machining tool and the metal part, as well as to reduce, or even prevent, the appearance of gummy residues after a metal machining operation using said composition as a lubricating fluid.

[0044] The invention also relates, according to another of its aspects, to a method for lubricating the tool (or apparatus) implemented for a metal machining operation and / or a metal workpiece, comprising at least one step of bringing a portion of the surface of said tool and / or said workpiece into contact with at least one aqueous lubricating composition according to the invention.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] The expressions "between ... and ...", "ranging from ... to ...", "formed from ... to ...", and "varying from ... to ...", must be understood inclusively, unless otherwise stated.

[0049] 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

[0050] 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.

[0051] For the purposes of the invention, the term “majority solvent” is understood to mean that water is present in greater quantity than any other solvent possibly present in the composition.

[0052] 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.

[0053] By its role as a solvent, water makes it possible to solubilize the polyalkylene glycol(s) and the alkoxylated, preferably ethoxylated, castor oil used according to the invention, as well as any additive optionally present in the composition, in particular chosen from those detailed in the rest of the text.

[0054] 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.

[0055] According to a particular embodiment, the water used in an aqueous lubricating composition according to the invention is deionized water or osmosis water.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] Advantageously, an aqueous lubricating composition according to the invention is completely free of oil which is not soluble in water. POLYALKYLENE GLYCOL

[0063] As indicated previously, an aqueous lubricating composition according to the invention comprises from 0.1 to 15% by mass of at least one polyalkylene glycol.

[0064] It is understood that a lubricating composition according to the invention may comprise a single polyalkylene glycol, or a mixture of at least two distinct polyalkylene glycols, in particular as described below.

[0065] Polyalkylene glycols (denoted “PAGs”) are homo- or co-polymers made up of alkylene oxide units.

[0066] In particular, polyalkylene glycols are not used in a composition according to the invention as emulsifiers.

[0067] According to the invention, the polyalkylene glycols are soluble in water.

[0068] 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).

[0069] 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 .

[0070] 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.

[0071] 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.

[0072] 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< .

[0073] The number-average molar mass can be measured by gel permeation chromatography (GPC).

[0074] 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.

[0075] 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 < / .

[0076] 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.

[0077] 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.

[0078] 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.

[0079] Said polyalkylene glycol compound(s) are used in an aqueous lubricating composition according to the invention in a content of 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. ALCOXYLATED CASTOR OIL

[0080] As indicated previously, an aqueous lubricating composition according to the invention comprises from 0.1 to 15% by mass of at least one alkoxylated, in particular ethoxylated, castor oil.

[0081] In particular, alkoxylated castor oil, in particular ethoxylated castor oil, is not used in a composition according to the invention as an emulsifier.

[0082] 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.

[0083] 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.

[0084] Alkoxylated castor oil is formed from alkoxylated triglycerides.

[0085] Preferably, a lubricating composition according to the invention comprises an alkoxylated (C 1 -C 4 ) castor oil, preferably ethoxylated.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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”.

[0091] As mentioned above, the alkoxylated castor oil, preferably ethoxylated, in particular as described above, is used in an amount of 0.1% to 15% 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. ADDITIVES

[0092] An aqueous lubricating composition according to the invention may further comprise various additives.

[0093] 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.

[0094] The said additive(s) are of course chosen with regard to the intended application for the aqueous lubricant.

[0095] 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 reducing gummy residues, after the use of the lubricating composition for metalworking and the tribological properties, in particular extreme pressure properties and protection of parts against wear, are not altered by the envisaged addition.

[0096] Such additives may be more particularly chosen from anti-foaming agents, biocides, pH regulators, corrosion inhibitors, anti-wear and / or extreme pressure additives, sequestering agents, metal passivating agents, colorants, dispersants, emulsifying agents, wetting agents, and mixtures thereof.

[0097] 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.

[0098] 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

[0099] 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.

[0100] 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.

[0101] 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-wear / extreme pressure additive

[0102] An aqueous lubricating composition according to the invention may comprise at least one anti-wear and / or extreme pressure additive. Their function is to reduce wear and the coefficient of friction, or to prevent metal-metal contact by forming a protective film adsorbed on these surfaces.

[0103] An aqueous lubricating composition according to the invention may comprise between 0.001% and 50% by mass of anti-wear and / or extreme pressure additive(s), in particular sulfur-containing fatty acid(s), as defined above, preferably between 0.2% and 5% by mass, relative to the total mass of the composition.

[0104] Advantageously, a composition according to the invention, combining at least one polyalkylene glycol and at least one alkoxylated, in particular ethoxylated, castor oil, has good anti-wear and extreme pressure properties, even in the absence of additional anti-wear and / or extreme pressure additives.

[0105] Thus, according to a particular embodiment, a lubricating composition according to the invention comprises less than 1% by mass of anti-wear and / or extreme pressure additives, in particular less than 0.5% by mass, in particular less than 0.1% by mass of anti-wear and / or extreme pressure additives, or even is free of anti-wear and / or extreme pressure additive. Anti-foam

[0106] 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.

[0107] 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.

[0108] Also, antifoam agents can be polar polymers such as polymethylsiloxanes or polyacrylates.

[0109] 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

[0110] 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.

[0111] The pH regulator can be chosen from the amine family, in particular alkanolamines and amino alcohols.

[0112] 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.

[0113] 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

[0114] 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.

[0115] 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.

[0116] Preferably, the metal passivating agents are chosen from tetrahydrobenzotriazole (THBTZ), tolyltriazole (TTZ), benzotriazole (BTZ), and their salts, taken alone or in mixtures.

[0117] 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

[0118] 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.

[0119] 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

[0120] 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.

[0121] 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, 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.

[0122] 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

[0123] 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.

[0124] 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-hydroxyethylamine di(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, polysaccharides and carbohydrates, such as inulin, carboxymethylinulin and carboxymethylchitosan.

[0125] 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

[0126] An aqueous lubricating composition according to the invention may comprise at least one biocidal agent with fungicidal and / or bactericidal 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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 0.1% to 15% by mass of at least one water-soluble polyalkylene glycol, in particular as defined above; from 0.1% to 15% by mass of at least one alkoxylated, preferably ethoxylated, castor oil; 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.

[0131] In particular, an aqueous lubricating composition according to the invention may consist of: 0.1% to 15% by mass of at least one water-soluble polyalkylene glycol, in particular as defined above; 0.1% to 15% by mass of at least one alkoxylated, preferably ethoxylated, castor oil; 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.

[0132] 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.

[0133] 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 Evaluation of tribological properties

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] The wear diameter values ​​provided in the following examples are those obtained for the load value preceding ball welding.

[0139] It is common practice to dilute compositions before carrying out load tests, and the dilution rate is therefore specified in the results below. Measurement of gummy residue formation

[0140] The test for assessing the formation of gummy residues is taken from ISO / TS 12-927 part B.6, for which the time and temperature parameters have been adapted.

[0141] This standard allows the residual sticky, gummy appearance of a product to be simulated. Thus, this test makes it possible to assess whether a product remaining on the machine at a standstill after machining, for example left in the open air, will tend to cause a blocking phenomenon upon restart, due to the presence of dried residue sticking to the tooling.

[0142] The formation of gummy residues is quantified by measuring the mass of non-water-soluble residues after use of the composition.

[0143] To do this, the composition to be tested is placed in a ventilated oven at a temperature of 90°C for 20 hours. The mass of the composition is measured before and after passing through the oven. The composition is then solubilized in reverse osmosis water for 15 minutes at room temperature and with mechanical stirring at a speed of 600 rpm. The insoluble residues correspond to the gummy residues formed. These are filtered and weighed to determine the quantity in milligrams. The greater the quantity of residues, the more this means that the lubricating composition will tend to form undesirable gummy residues after its use as a lubricant in machining machines. Example 1 : Preparation of lubricating compositions I1, C1 and C2

[0144] An aqueous lubricating composition according to the invention ( I1 ), and two comparative aqueous lubricating compositions, C1 not including polyalkylene glycol and C2not including alkoxylated castor oil, were formulated according to the protocol below, in the mass percentages indicated in the following table 1.

[0145] The formulation protocol is as follows: Alkoxylated castor oil is dissolved in reverse osmosis water. The solution is stirred for 30 minutes at room temperature (around 20°C). At this stage, the solution may not be clear.

[0146] 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, then possibly wetting agent(s), antifoam agent(s) and biocide(s).

[0147] Finally, a final stirring is carried out for 1 hour. [Table 1] Composition I1 according to the invention C1 excluding invention C2 outside invention Osmosis water [%] 65,01 68,01 68,01 Polyalkylene glycol 1 [%] - - 3 Polyalkylene glycol 2 [%] 3 - - Ethoxylated castor oil [%] 3 3 - Additive(s) (1)< 28,99 28,99 28,99 (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 comparative

[0148] Tribological properties were measured for each composition as detailed in the protocol above.

[0149] The results are compiled in Table 2 below. [Table 2] Composition Dilution rate [%] Welding load [kg] Wear diameter [mm] I1 (invention) 10 180 1,9 - 2,0 C1 (comparative) 10 160 2,0 - 2,1 C2 (comparative) 10 180 1,9 - 2,0

[0150] Composition I1 according to the invention has a weld load equivalent to that obtained for comparative composition C2 and better than that obtained for comparative composition C1, and a wear diameter of the same order of magnitude.

[0151] Thus, a lubricating composition in accordance with the invention, incorporating at least one polyalkylene glycol and alkoxylated castor oil, has excellent extreme pressure and anti-wear properties, equivalent or even better than those obtained with a composition not comprising such a combination of ingredients.

[0152] Furthermore, the gummy residues were quantified for each composition, and the results are provided in Table 3 below. [Table 3] Composition Mass variation after passage in oven [%] Water-insoluble mass [m g ] I1 (Invention) 98,7 2,7 C1 (Comparative) 98,9 16,4 C2 (Comparative) 98,8 14,3

[0153] Composition I1 according to the invention has a mass of insoluble compounds, corresponding to the gummy residues, significantly lower than those obtained for comparative compositions C1 and C2.

[0154] Thus, a lubricating composition in accordance with the invention, combining at least one polyalkylene glycol and alkoxylated, in particular ethoxylated, castor oil, advantageously makes it possible to lead to significantly reduced quantities of gummy residues, after its use in the machining equipment. Example 3 : Preparation of lubricating composition I2

[0155] An aqueous lubricating composition according to the invention (I2) was formulated according to the protocol below, in the mass percentages indicated in the following table 4.

[0156] The formulation protocol is identical to that detailed in example 1. [Table 4] Composition I2 according to the invention Osmosis water [%] 51,01 Polyalkylene glycol 2 [%] 10 Ethoxylated castor oil [%] 10 Additive(s) (1)< 28,99 (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 composition according to the invention

[0157] The tribological properties were measured for composition I2 according to the invention, as detailed in the protocol described previously.

[0158] The results are compiled in Table 5 below. [Table 5] Composition Dilution rate [%] Welding load [kg] Wear diameter [mm] I2 (invention) 10 180 1,5 - 1,6

[0159] Composition I2 according to the invention has a high weld load. It also has a low wear diameter.

[0160] Thus, a lubricating composition in accordance with the invention, incorporating at least one polyalkylene glycol and alkoxylated castor oil, has excellent extreme pressure and anti-wear properties.

[0161] Furthermore, the gummy residues were quantified for composition I2 according to the invention, and the results are provided in Table 6 below. [Table 6] Composition Mass variation after passage in oven [%] Water-insoluble mass [m g ] I2 (invention) 96,8 0

[0162] Composition I2 according to the invention has a zero mass of insoluble compounds, corresponding to the gummy residues.

[0163] Thus, a lubricating composition in accordance with the invention, combining at least one polyalkylene glycol and alkoxylated, in particular ethoxylated, castor oil, advantageously makes it possible to lead to significantly reduced quantities of gummy residues, after its use in the machining equipment.

Claims

1. Aqueous lubricating composition, in particular for metalworking, comprising at least: - at least 50% by weight of water, preferably of osmosed water; - from 0.1% to 15% by weight of at least one water-soluble polyalkylene glycol; and - from 0.1% to 15% by weight of at least one alkoxylated, preferably ethoxylated, castor oil, 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 said composition.

3. Aqueous lubricating composition according to Claim 1 or 2, in which said polyalkylene glycol(s) are chosen from copolymers, in particular random copolymers, comprising ethylene oxide, propylene oxide and / or butylene oxide units.

4. Aqueous lubricating composition according to any one of the preceding claims, comprising from 1% to 10% by weight of polyalkylene glycol(s), more preferentially 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, 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.

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

7. Aqueous lubricating composition according to any one of the preceding claims, comprising one or more additives chosen from antifoaming agents, biocides, pH regulators, corrosion inhibitors, antiwear and / or extreme-pressure additives, sequestering agents, metal passivating agents, dyes, dispersants, emulsifying agents and their mixtures, in particular chosen from antifoaming agents, biocides, pH regulators, corrosion inhibitors, sequestering agents, metal passivating agents, emulsifying agents and their mixtures.

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

9. Use of an aqueous lubricating composition as defined according to any one of Claims 1 to 7, for reducing, indeed even preventing, the formation of gummy residues after a metal machining operation involving said composition as lubricating fluid.

10. Use of the combination of at least one water-soluble polyalkylene glycol and of at least one alkoxylated, in particular ethoxylated, castor oil in an aqueous lubricating composition, for reducing its propensity to form gummy residues after its employment as lubricant for metalworking.