US20240309286A1

US20240309286A1 - Aqueous lubricant composition for metalworking

Info

Publication number: US20240309286A1
Application number: US18/575,566
Authority: US
Inventors: Véronique Verroul; Richard Frelechoux
Original assignee: TotalEnergies Onetech SAS
Current assignee: TotalEnergies Onetech SAS
Priority date: 2021-07-01
Filing date: 2022-06-30
Publication date: 2024-09-19
Also published as: EP4363538A1; FR3124801A1; CN117916347A; WO2023275308A1; FR3124801B1; MX2024000102A

Abstract

The present invention relates to an aqueous lubricating composition comprising at least:water,from 0.001% to 80% by weight of at least one polyalkylene glycol; andfrom 0.001% to 50% by weight of at least one alkoxylated, preferably ethoxylated, castor oil.The present invention also relates to the use of an aqueous lubricating composition as lubricant in a metalworking process, in particular for reducing, indeed even preventing, the formation of gummy residues.

Description

TECHNICAL FIELD

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

PRIOR ART

Lubricating compositions, also known as “lubricants”, are commonly employed in mechanical systems to reduce frictional actions between parts and thus to protect them against wear. In addition to wear phenomena, frictional actions can oppose the relative movement of the parts in contact and induce energy losses which are detrimental to optimal functioning of the mechanical system.
Lubricants are used for multiple applications, from the lubrication of combustion vehicle engines to the lubrication of the apparatus employed for machining operations, what is commonly referred to as metalworking, especially for metal deformation operations.
Metalworking more generally corresponds to the implementation of mechanical or metallurgical processes, both diversified or more specialized, which can be defined as conformation, cutting or jointing processes. This can also concern any mechanical transformation of the metal, such as machining (turning, milling, drilling, sawing, threading, inter alia), forming, cutting, stamping or also rolling.
The operations relating to metalworking require very particularly the employment of lubricating compositions, with the aim of reducing the frictional forces between the metal parts in contact and of preventing their premature wear, while advantageously guaranteeing cooling of these.
These lubricating compositions, dedicated to lubrication in metal machining processes, are also commonly denoted under the names “metalworking compositions or fluids”, “machining lubricants or fluids” or also “cutting lubricants or fluids”.
Conventionally, the lubricating formulations employed for such machining operations are lubricants predominantly composed of one or more base oils, with which additives dedicated to stimulating the lubricating performance qualities of the base oils, such as, for example, friction-modifying additives, are generally combined.
In general, these lubricating formulations are classified from the viewpoint of the type of oil which they incorporate. Thus:

- nonrenewable mineral fluids are those comprising mineral oils, such as paraffinic, aromatic or naphthenic oils, in their base formulation;
- renewable fluids, of vegetable or animal origin, are those comprising vegetable oils, animal oils or fats in their base formulation;
- mineral fluids of synthetic origin are those comprising chemically modified mineral oils or petrochemical derivatives in their base formulation, such as, for example, poly-α-olefins, polyalkylene glycols and hydrogenated mineral oils;
- renewable fluids of synthetic origin are those comprising chemically modified vegetable or animal oils in their base formulation, such as, for example, esters of vegetable oils, sulfited, oxidized or esterified vegetable oils or also sulfated animal oils.

Certain formulations, referred to as mixed formulations, comprise a mixture of the oils listed above in their base formulation. The best known are called semisynthetic oils and correspond to a mixture of synthetic and mineral oils.
However, the use of oils or fats in lubricating compositions for metalworking exhibits several disadvantages. In particular, oil-based lubricants generally exhibit a low resistance to microbial attack, weak cooling properties or also a negative impact on the working environment, health or also safety.
Lubricants in emulsion form, comprising an aqueous phase added to an oily phase, have thus been developed. However, these lubricants exhibit poor stability, due in part to water hardness and/or to salinity.
With the aim of solving the problems related to the employment of oil-based lubricating formulations in metalworking applications, water-based compositions have shown a certain advantage. These formulations usually include water, supplemented by various additives in order to guarantee the tribological properties required for lubricants, especially in terms of reduction in friction and protection of the parts against wear.
Mention may be made, by way of examples, of the documents WO 2009/106359 and WO 2012/163550, which describe aqueous lubricating compositions comprising in particular water and carboxymethyl cellulose salts.
Mention may also be made of the document EP 3 042 946, which provides a metalworking fluid, devoid of oil and emulsifier, comprising between 0.1% and 2% by weight of a polymer of cellulose type.
Finally, the document GB 1 272 100 provides an aqueous lubricant for metalworking comprising (1) a linear polypropylene glycol or an ethylene oxide/propylene oxide copolymer with a molecular weight of between 2000 and 9000 Da and (2) a polyvinylpyrrolidone, a cellulose ether or a triethanolamine phosphate.
Unfortunately, the employment of aqueous lubricants for an application in metalworking exhibits a major disadvantage related to the formation of what are called “gummy residues”. These gummy residues appear subsequent to the machining operations. Once the machining apparatus has stopped, the lubricant, subject to ambient dehydration, is liable to result in the formation of salts which, combined with the polymers present in the lubricant, can form residues which are relatively viscous and insoluble in the aqueous phase, denoted under the name “gummy residues”.
The gummy residues adhere to the walls of the equipment and are liable to cause a blockage of the machining tool, generally requiring undesirable maintenance operations on the machine.
Thus, there remains a need to have available an aqueous lubricating composition, for metalworking, generating little or no gummy residues, while maintaining, indeed even while improving, the tribological properties of the lubricant, in particular in terms of antiwear and extreme-pressure properties.
The present invention is targeted precisely at meeting this need.

DISCLOSURE OF THE INVENTION

The present invention thus provides a novel aqueous lubricating composition exhibiting tribological properties, in particular extreme-pressure and antiwear properties, suited to its use for metalworking, and resulting in a slight formation, indeed even in the absence, of gummy residues after its use in the machining apparatus.
More particularly, there is described an aqueous lubricating composition, in particular for metalworking, comprising at least:

- water, preferably osmosed water;
- from 0.001% to 80% by weight of at least one polyalkylene glycol; and
- from 0.001% to 50% by weight of at least one alkoxylated, preferably ethoxylated, castor oil;
  the percentages being expressed with respect to the total weight of the composition.

Thus, the present invention relates, according to a first of its aspects, to an aqueous lubricating composition, in particular for metalworking, comprising at least:

- water, preferably 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.

In particular, the water-soluble polyalkylene glycol and/or the alkoxylated, preferably ethoxylated, castor oil are not employed as emulsifiers.
Within the meaning of the present invention, the term “aqueous composition” is understood to denote a composition comprising water as base fluid, in other words as predominant solvent. In particular, the water, preferably osmosed, preferably represents at least 50% by weight of the total weight of the lubricating composition.
In the continuation of the text, the term “aqueous lubricating composition” or “aqueous lubricant” will denote a water-based lubricating composition according to the invention.
Within the meaning of the present invention, the term “osmosed water” is understood to denote water which 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 of less than 1.0% by weight. In the continuation of the text, the expressions “demineralized water” or also “ultrapure water” will be considered as equivalent to or synonymous with the expression “osmosed water”. In particular, the osmosed water can be “deionized water”, in other words water which has undergone a purification in order to reduce the content of ions, such as Ca²⁺ and HCO₃ ⁻ions, typically present in water. Preferably, deionized water does not comprise ions.
Contrary to all expectations, the inventors have discovered that the combined employment of at least one polyalkylene glycol and of at least one alkoxylated, in particular ethoxylated, castor oil makes it possible to obtain an aqueous fluid exhibiting excellent tribological properties, suited to its employment as lubricant for metalworking, while resulting in very low formation of gummy residues after use.
Thus, as illustrated in the examples which follow, it is possible, by supplementing an aqueous formulation, by the combination of at least one polyalkylene glycol and of at least one alkoxylated, in particular ethoxylated, castor oil, to access a lubricating fluid resulting in a significantly reduced formation of gummy residues.
The combination of at least one polyalkylene glycol and of an alkoxylated, in particular ethoxylated, castor oil in an aqueous lubricating composition exhibits more particularly a synergistic effect on the reduction in the formation of gummy residues after use, while not impacting, indeed even while improving, the antiwear and extreme-pressure properties of the aqueous lubricant.
The propensity of a lubricating formulation to form gummy residues can be evaluated as described in the examples which follow.
There is thus described the use of the combination of at least one 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.
The invention thus relates to the 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.
Furthermore, the combination of at least one polyalkylene glycol and of at least one alkoxylated castor oil does not impact the tribological properties of the lubricating formulation, in particular the performance qualities of reductions in frictional actions, under extreme-pressure conditions.
The aqueous lubricating composition according to the invention thus exhibits good antiwear and extreme-pressure properties, indeed even, surprisingly, antiwear and/or extreme-pressure properties which are improved, compared with a composition not comprising alkoxylated castor oil or polyalkylene glycol according to the invention.
The antiwear and extreme-pressure properties can be evaluated by a 4-ball extreme-pressure test, in particular according to the standard ASTM D2783, as described in detail in the examples below. As demonstrated in the examples, an aqueous lubricating composition according to the invention makes it possible to achieve high weld load values, without significant increase in the wear diameter, which testifies to its excellent tribological properties.
Thus, the aqueous compositions according to the invention prove to be particularly advantageous for employment as lubricants for metalworking. They can thus be employed as metalworking fluids, for various applications, as a substitute for the lubricants conventionally employed, in particular hydrocarbon lubricants.
The invention thus relates, according to another of its aspects, to the use of an aqueous lubricating composition according to the invention as lubricant in a metalworking process.
An aqueous composition according to the invention can more particularly be employed as lubricant in any metal machining operation, for example in conformation, cutting or jointing processes or any other transformation of the metal, such as forming, stamping, rolling, and the like.
It can be intended to be employed for the working of varied metals, such as aluminum, steel, galvanized steel or also yellow metals.
The invention also relates to a metalworking process employing, as lubricant, an aqueous lubricating composition according to the invention. Said process comprises in particular a stage of application of an aqueous lubricating composition according to the invention to the surface of at least a portion of the machining tool (or apparatus) and/or of a metal part to be machined.
The lubricating fluid according to the invention advantageously makes it possible to reduce the friction between the machining tool or apparatus and the machined metal part.
The present invention also relates to the use of an aqueous lubricating composition according to the invention for reducing, indeed even preventing (avoiding), the formation of gummy residues after a metal machining operation involving said composition as lubricating fluid.
It relates more particularly to the use of an aqueous lubricating composition according to the invention for reducing frictional actions during a metal machining operation, in particular the frictional actions between the machining tool and the metal part, and also for reducing, indeed even preventing, the appearance of gummy residues after a metal machining operation involving said composition as lubricating fluid.
The invention also relates, according to another of its aspects, to a process of lubrication of the tool (or apparatus) employed for a metal machining operation and/or of a metal part to be machined, comprising at least one stage of bringing a portion of the surface of said tool and/or of said part into contact with at least one aqueous lubricating composition according to the invention.
Finally, advantageously, a lubricating composition according to the invention, formed predominantly of water, exhibits little toxicological impact, in particular for persons employing this lubricant. Advantageously, even though water is the predominant solvent of an aqueous lubricant according to the invention, the treated surface is properly lubricated.
In addition, the presence of a large proportion of water makes it possible to facilitate the cleaning of metal surfaces and the removal of the lubricant after machining, in particular by simply passing or rinsing with water.
Other characteristics, alternative forms and advantages of an aqueous lubricating composition according to the invention will become clearer on reading the description and the examples which follow, given by way of illustration and without limitation of the invention.
The expressions “of between . . . and . . . ”, “ranging from . . . to . . . ”, “formed of . . . to . . . ” and “varying from . . . to . . . ” should be understood as limits included, unless otherwise mentioned.
In the description and the examples, unless otherwise indicated, the percentages are percentages by weight. The percentages are thus expressed by weight, with respect to the total weight of the composition. The temperature is expressed in degrees Celsius, unless otherwise indicated, and the pressure is atmospheric pressure, unless otherwise indicated.

DETAILED DESCRIPTION

Aqueous Composition

As mentioned above, an aqueous lubricating composition according to the invention, also referred to as aqueous lubricant, is a formulation comprising water as predominant solvent. Within the meaning of the invention, the term “predominant solvent” is understood to mean that water is present in a greater amount than any other solvent possibly present in the composition. Preferably, an aqueous lubricating composition according to the invention comprises at least 50% by weight of water, in particular of osmosed water, preferably between 50% and 90% by weight, more preferentially between 60% and 75% by weight, with respect to the total weight of the composition.
By virtue of its role as solvent, water makes it possible to dissolve the polyalkylene glycol(s) and the alkoxylated, preferably ethoxylated, castor oil employed according to the invention, and also any additive optionally present in the composition, in particular chosen from those described in detail in the continuation of the text.
Advantageously, besides its role as solvent, water makes it possible to access a lubricating composition exhibiting good cooling properties, of use in the field of the machining of metals.
According to a particular embodiment, the water employed in an aqueous lubricating composition according to the invention is deionized water or osmosed water.
Advantageously, deionized water does not comprise ions, such as Ca²⁺ and HCO₃ ⁻ions, generally present in water, which are responsible for the conduction of electricity in water.
The employment of deionized water is thus particularly advantageous in the context of the use of the aqueous lubricant according to the invention for applications requiring a fluid which conducts little, indeed even no, electricity.
An aqueous lubricating composition according to the invention differs from hydrocarbon lubricants, which comprise a predominant proportion of one or more water-insoluble base oils.
The term “water-insoluble oil” is understood to mean in particular an oil which does not dissolve substantially in water at ambient temperature (at approximately 25° C.). In particular, a water-insoluble oil exhibits a solubility in water of less than 0.2 g/l at ambient temperature. This concerns in particular the 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.
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, with respect to the total weight of the composition.
Advantageously, an aqueous lubricating composition according to the invention is completely devoid of water-insoluble oil.

Polyalkylene Glycol

As indicated above, an aqueous lubricating composition according to the invention comprises from 0.1% to 15% by weight of at least one polyalkylene glycol.
It is understood that a lubricating composition according to the invention can comprise a single polyalkylene glycol, or a mixture of at least two distinct polyalkylene glycols, in particular as are described below.
Polyalkylene glycols (denoted “PAGs”) are homo- or copolymers consisting of alkylene oxide units.
In particular, polyalkylene glycols are not employed in a composition according to the invention as emulsifiers.
According to the invention, the polyalkylene glycols are water-soluble.
The term “water-soluble” is understood to denote a polyalkylene glycol having a solubility in water of at least 10 g/l, preferably of at least 500 g/l, in water at ambient temperature (approximately 25° C.).
The polyalkylene glycols can be more particularly formed of C₁-C₄, preferably C₁-C₃, more particularly C₂-C₃, alkylene oxide units.
Advantageously, a polyalkylene glycol employed in an aqueous lubricating composition according to the invention comprises at least 50% by weight of propylene oxide and/or ethylene oxide units.
It can concern a copolymer, in particular a random copolymer, comprising ethylene oxide, propylene oxide and/or butylene oxide units. Preferably, it can concern an ethylene oxide/propylene oxide copolymer, in particular a random copolymer.
Preferably, a polyalkylene glycol employed in an aqueous lubricating composition according to the invention exhibits a number-average molar mass (Mn) of between 100 and 25 000 g·mol⁻¹, preferably between 5000 and 21 000 g·mol⁻¹.
The number-average molar mass can be measured by gel permeation chromatography (GPC).
Preferably, a polyalkylene glycol employed in an aqueous lubricating composition according to the invention exhibits a kinematic viscosity measured at 100° C. (KV100), according to the standard ASTM D445, of between 100 and 5000 mm²/s, in particular between 150 and 3000 mm²/s, for example between 1500 and 3000 mm²/s or between 100 and 250 mm²/s.
Preferably, a polyalkylene glycol employed in an aqueous lubricating composition according to the invention exhibits a kinematic viscosity measured at 40° C. (KV40), according to the standard ASTM D445, of between 500 and 30 000 mm²/s, more particularly between 1000 and 25 000 mm²/s, for example between 10 000 and 25 000 mm²/s or between 500 and 2500 mm²/s.
The flash point of a polyalkylene glycol employed 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 of between 220° C. and 300° C. The flash point can be measured by the standard ISO 2592 or ASTM D92.
Preferably, a polyalkylene glycol employed in an aqueous lubricating composition according to the invention exhibits a viscosity index, measured according to the standard ASTM D2270, of between 100 and 800, preferably between 250 and 550.
Such polyalkylene glycols may be commercially available or synthesized according to methods known to a person skilled in the art. They can 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, described in detail in the document US2012/0108482, 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 can preferably be a diol, in particular 1,2-propanediol.
Said polyalkylene glycol compound(s) are employed in an aqueous lubricating composition according to the invention in a content of between 0.1% and 15% by weight, more preferentially between 1% and 10% by weight, in particular between 2% and 5% by weight, with respect to the total weight of the composition.

Alkoxylated Castor Oil

As indicated above, an aqueous lubricating composition according to the invention comprises from 0.1% to 15% by weight of at least one alkoxylated, in particular ethoxylated, castor oil.
In particular, the alkoxylated, in particular ethoxylated, castor oil is not employed in a composition according to the invention as emulsifier.
It is understood that a lubricating composition according to the invention can comprise a single alkoxylated, in particular ethoxylated, castor oil or a mixture of at least two distinct particular alkoxylated castor oils, in particular as are described below.
Castor oil is composed of fatty acid, predominantly C₁₆to C₁₈fatty acid, triglycerides. More particularly, ricinolein, the triglyceride of ricinoleic acid (C₁₈fatty acid), is the major constituent of castor oil.
An alkoxylated castor oil is formed of alkoxylated triglycerides.
Preferably, a lubricating composition according to the invention comprises a (C₁-C₄) alkoxylated, preferably ethoxylated, castor oil.
It can be obtained by alkoxylation of castor oil with an alkylene oxide, in particular a C₁to C₄alkylene oxide, or also by transesterification with a polyalkylene glycol, in particular a poly(C₁-C₄)alkylene glycol.
Preferably, a lubricating composition according to the invention employs an ethoxylated castor oil. It can be obtained by ethoxylation of castor oil with ethylene oxide or also by transesterification of castor oil with a polyethylene glycol.
According to a particular embodiment, a lubricating composition according to the invention employs 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.
An ethoxylated castor oil employed in a lubricating composition according to the invention can comprise in particular at least 20 oxyethylene groups, preferably from 35 to 45 oxyethylene groups.
Preferably, it concerns an ethoxylated castor oil obtained by reaction of castor oil with ethylene oxide, in a castor oil:ethylene oxide molar ratio of approximately 1:35, denoted “PEG-35-castor oil”.
As mentioned above, the alkoxylated, preferably ethoxylated, castor oil, in particular as described above, is employed in a proportion of 0.1% to 15% by weight, with respect to the total weight of the composition, in particular of 1% to 10% by weight and more particularly of 2% to 5% by weight, with respect to the total weight of the composition.

Additives

An aqueous lubricating composition according to the invention can additionally comprise various additives.
It is understood that said additive(s) are compatible with their employment in an aqueous medium. Advantageously, the additives are employed in a form which is soluble or emulsifiable in water, for example in the form of ionic liquids or salts.
Said additive(s) are of course chosen from the viewpoint of the application targeted for the aqueous lubricant.
Of course, a person skilled in the art will take care to choose the optional additives and/or their amounts in such a way that the advantageous properties of the aqueous lubricating composition according to the invention, in particular the advantageous effect of reduction of the gummy residues, subsequent to the employment of the lubricating composition for metalworking, and the tribological properties, in particular extreme-pressure properties and protection of the parts against wear, are not detrimentally affected by the envisaged addition. Such additives can be more particularly chosen from antifoaming agents, biocides, pH regulators, corrosion inhibitors, antiwear and/or extreme-pressure additives, sequestering agents, metal passivating agents, dyes, dispersants, emulsifying agents, wetting agents and their mixtures.
Advantageously, an aqueous lubricating composition according to the invention can comprise one or more additives chosen from antifoaming agents, biocides, pH regulators, corrosion inhibitors, sequestering agents, metal passivating agents, emulsifying agents and their mixtures.
An aqueous lubricating composition according to the invention can more particularly comprise from 1% to 50% by weight of additives, in particular from 5% to 40% by weight of additives, with respect to the total weight of the composition.

Corrosion Inhibitor

An aqueous lubricating composition according to the invention can comprise at least one agent which inhibits corrosion. Corrosion inhibitors make it possible advantageously to reduce, indeed even to prevent, the corrosion of the metal parts. The nature of said corrosion inhibitor(s) can be chosen from the viewpoint of the metal to be protected against corrosion, such as aluminum, steel, galvanized steel or yellow metals, for example copper or brass.
Mention may be made, among inorganic corrosion inhibitors, of sodium, potassium, calcium or magnesium nitrites, sulfites, silicates, borates or phosphates, alkali metal phosphates, or zinc, magnesium or nickel hydroxides, molybdates or sulfates.
Mention may be made, among organic corrosion inhibitors, of 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 their mixtures, polycarboxylic acids optionally neutralized with 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 their mixtures. Borated amides, products of the reaction of amines or aminoalcohols with boric acid, can also be used.
An aqueous lubricating composition according to the invention can in particular comprise from 0.01% to 15% by weight of corrosion inhibitor(s), preferably from 1.0% to 13% by weight, with respect to the total weight of the composition.

Antiwear/Extreme-Pressure Additive

An aqueous lubricating composition according to the invention can comprise at least one antiwear and/or extreme-pressure additive. Their function is to reduce wear and the coefficient of friction, or also to prevent metal-metal contact by formation of a protective film adsorbed on these surfaces.
An aqueous lubricating composition according to the invention can comprise between 0.001% and 50% by weight of antiwear and/or extreme-pressure additive(s) as are defined above, in particular of sulfur-containing fatty acid(s), preferably between 0.2% and 5% by weight, with respect to the total weight of the composition.
Advantageously, a composition according to the invention, combining at least one polyalkylene glycol and at least one alkoxylated, in particular ethoxylated, castor oil, exhibits good antiwear and extreme-pressure properties, even in the absence of additional antiwear and/or extreme-pressure additives.
Thus, according to a particular embodiment, a lubricating composition according to the invention comprises less than 1% by weight of antiwear and/or extreme-pressure additives, especially less than 0.5% by weight, in particular less than 0.1% by weight, of antiwear and/or extreme-pressure additives, indeed even is devoid of antiwear and/or extreme-pressure additive.

Antifoaming Agent

An aqueous lubricating composition according to the invention can comprise at least one antifoaming additive. Antifoaming agents make it possible to prevent foaming of the lubricating fluid.
It can concern, for example, an antifoaming agent based on polysiloxanes or on acrylate polymers. Preferably, the antifoaming agent is chosen from three-dimensional siloxanes.
Also, the antifoaming agents can be polar polymers, such as polymethylsiloxanes or polyacrylates.
In particular, an aqueous lubricating composition according to the invention can comprise from 0.001% to 3.0% by weight of antifoaming additive(s), preferably from 0.005% to 1.5% by weight, with respect to the total weight of the lubricating composition.

pH Regulator

An aqueous lubricating composition according to the invention can comprise at least one additive which is a pH regulator, 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 of between 8 and 11, so as in particular to prevent corrosion of the metal surfaces.
The pH regulator can be chosen from the family of the amines, in particular alkanolamines and aminoalcohols.
It can in particular concern an additive which is a pH regulator chosen from ethanolamines, such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA) or diglycolamine (DGA), isopropanolamines, such as monoisopropanolamine (MIPA), diisopropanolamine (DIPA) and triisopropanolamine (TIPA), ethyleneamines, such as ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA) and tetraethylenepentamine (TEPA), alkanolamines, such as methyldiethanolamine (MDEA), cyclamines, such as cyclohexylamine, 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1-propanol and their mixtures.
An aqueous lubricating composition according to the invention can in particular comprise from 1% to 25% by weight of additive(s) which is (are) pH regulator(s), preferably from 5% to 20% by weight, with respect to the total weight of the composition.

Metal Passivating Agents

An aqueous lubricating composition according to the invention can comprise at least one metal passivating agent. Metal passivating agents make it possible to protect metal parts by promoting the formation of metal oxide at their surface.
The metal passivating agents can, for example, be chosen from triazole derivatives, such as tetrahydrobenzotriazole (THBTZ), tolyltriazole (TTZ), benzotriazole (BTZ), amines substituted by a triazole group, such as N,N-bis(2-ethylhexyl)-1,2,4-triazol-1-ylmethanamine, N′,N′-bis(2-ethylhexyl)-4-methyl-1H-benzotriazol-1-methylamine, N,N-bis(heptyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(nonyl)-ar-methyl-1H-benzotriazole-1-methanamine, N,N-bis(decyl)-ar-methyl-1H-benzotriazole-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 their mixtures.
Preferably, the metal passivating agents are chosen from tetrahydrobenzotriazole (THBTZ), tolyltriazole (TTZ), benzotriazole (BTZ) and their salts, taken alone or as mixtures.
An aqueous lubricating composition according to the invention can in particular comprise from 0.01% to 2.0% by weight of metal passivating agent(s), preferably from 0.1% to 1.0% by weight, more preferentially from 0.2% to 0.8% by weight, with respect to the total weight of the composition.

Dyes

An aqueous lubricating composition according to the invention can comprise one or more dyes. The dyes can be natural or synthetic, generally organic.
The dyes which can be employed in an aqueous lubricating composition can be more particularly chosen from natural or synthetic water-soluble dyes, for example the dyes 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 (beet), carmine, a chlorophyllin, methylene blue, anthocyanins (enocyanin, black carrot and hibiscus), caramel and riboflavin.
An aqueous lubricating composition according to the invention can comprise between 0.01% and 2.0% by weight of dye(s), preferably between 0.01% and 1.5% by weight, more preferentially between 0.02% and 1.0% by weight, with respect to the total weight of the composition.

Emulsifying Agents

An aqueous lubricating composition according to the invention can comprise one or more emulsifying agents, also called emulsifiers. Their function is to generate emulsions which are stable in water.
The emulsifying agents can more particularly be nonionic, such as, for example, ethoxylated fatty alcohols, ethoxylated fatty acids, compounds resulting from the reaction between propylene oxide, ethylenediamine and optionally ethylene oxide, ethoxylated fatty amides; anionic, for example KOH or NaOH soaps; sulfonates; cationic, such as quaternary ammonium compounds; or also water-soluble or water-emulsifiable carboxylic acid esters.
In particular, an aqueous lubricating composition according to the invention can comprise from 0.01% to 10% by weight of emulsifying agent(s), preferably from 0.1% to 5.0% by weight, with respect to the total weight of the lubricating composition.

Sequestering Agents

An aqueous lubricating composition according to the invention can 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.
Mention may be made, as examples of sequestering agents, of those derived from phosphonic acids and phosphonates, such as diethylenetriaminepentamethylenephosphonic acid (DTPMPA), aminotri(methylenephosphonic acid) (ATMP), hydroxyethanediphosphonic acid (HEDP), 1-hydroxyethylidene-1,1-diphosphonate, 2-hydroxyethylaminodi(methylenephosphonic acid) (HEAMBP), diethylenetriaminepenta(methylenephosphonic acid) (DTMP), multifunctional organic acids and hydroxylated 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, carboxymethyl inulin and carboxymethyl chitosan.
An aqueous lubricating composition according to the invention can comprise from 0.001% to 2.0% by weight of sequestering agent(s), preferably from 0.01% to 1.0% by weight, with respect to the total weight of the composition.

Biocides

An aqueous lubricating composition according to the invention can comprise at least one biocidal agent having a fungicidal and/or bactericidal action. The biocides can be used to improve the biological stability of the composition by limiting the proliferation of bacteria, fungi and yeasts in the lubricating fluid.
Such biocides can be chosen from parabens, aldehydes, reactive acetylacetone compounds, isothiazolinones, phenolic compounds, acid salts, halogenated compounds, quaternary ammoniums, certain alcohols and their mixtures.
Preferably, the biocides can be chosen from optionally substituted benzisothiazolinones (BITs), such as N-butyl-1,2-benzisothiazolin-3-one, methylisothiazolinones (MITs), mixtures of methylisothiazolinone and of chloromethylisothiazolinone (MIT/CMIT), ortho-phenylphenol (OPP) or its sodium salt, 3-iodo-2-propynyl butylcarbamate (IPBC), chloro-cresol and N,N-methylenebismorpholine (MBM); sorbic acid; preferably from ortho-phenylphenol (OPP) or its sodium salt, 3-iodo-2-propynyl butylcarbamate, chloro-cresol, benzisothiazolinones and N,N-methylenebismorpholine.
An aqueous lubricating composition according to the invention can in particular comprise between 0.01% and 10% by weight of biocide(s), preferably between 0.1% and 5.0% by weight, with respect to the total weight of the composition.
According to a particular embodiment, an aqueous lubricating composition according to the invention comprises:

- 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, in particular as defined above;
- from 0.1% to 15% by weight of at least one alkoxylated, preferably ethoxylated, castor oil; and
- optionally from 1% to 50% by weight, in particular from 5% to 40% by weight, of one or more additives chosen from antifoaming agents, biocides, pH regulators, corrosion inhibitors, sequestering agents, metal passivating agents, emulsifying agents and their mixtures,
  the contents being expressed with respect to the total weight of the lubricating composition.

In particular, an aqueous lubricating composition according to the invention can consist of:

- from 0.1% to 15% by weight of at least one water-soluble polyalkylene glycol, in particular as defined above;
- from 0.1% to 15% by weight of at least one alkoxylated, preferably ethoxylated, castor oil; and
- optionally from 1% to 50% by weight, in particular from 5% to 40% by weight, of one or more additives chosen from antifoaming agents, biocides, pH regulators, corrosion inhibitors, sequestering agents, metal passivating agents, emulsifying agents and their mixtures,
  the contents being expressed with respect to the total weight of the lubricating composition, and
  the remainder consisting of water, preferably of osmosed water.

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.
The invention will now be described by means of the following examples given, of course, by way of nonlimiting illustration of the invention.

Example

Evaluation of the Tribological Properties

The extreme-pressure and antiwear properties of the lubricating compositions are evaluated by the 4-ball test according to the standard ASTM D2783 adapted with the following parameters:

- speed close to 1500 revolutions/minute,
- ambient temperature, i.e. approximately 20° C.,
- loading time of 1 minute.

The extreme-pressure measurement is carried out by rotation of a stainless steel ball on three balls, also made of stainless steel, which are kept stationary, the four balls being completely 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 the load.
The extreme-pressure power corresponds to the value of the load from which the four balls weld together, preventing the rotation of the upper ball on the other three. The greater the load, the greater the extreme-pressure power.
This method also makes it possible to evaluate the antiwear properties of a lubricating composition. During the gradual increase in load, it is possible to determine, at each stationary phase, the wear diameter on the three balls. The smaller the wear diameter, the more effective the lubricant is in preventing wear (or seizure) of the parts.
The wear diameter values provided in the examples which follow are those obtained for the load value preceding the welding of the balls.
It is common practice to dilute the compositions before carrying out the load tests, and the dilution ratio is thus specified in the results below.

Measurement of the Formation of Gummy Residue

The test of evaluation of the formation of the gummy residues is taken from the standard ISO/TS 12-927 Part B.6, for which the time and temperature parameters have been adapted. This standard makes it possible to simulate the residual sticky gummy appearance of a product. Thus, this test makes it possible to evaluate if a product remaining on the machine when stopped after machining, for example left in the open air, will tend to cause a blocking phenomenon on restart, due to the presence of the dried residues sticking to the equipment. The formation of the gummy residues is quantified by measurement of the weight of water-insoluble residues after use of the composition.
To do this, the composition to be tested is placed in a ventilated oven at a temperature of 90° C. for 20 h. The weight of composition is measured before and after passage through the oven.
The composition is subsequently dissolved in osmosed water at ambient temperature for 15 minutes and with mechanical stirring at a speed of 600 revolutions/minute. The insoluble residues correspond to the gummy residues formed. The latter are filtered off and weighed in order to determine the amount thereof in milligrams. The greater the amount of residues, the more this means that the lubricating composition will tend to form undesirable gummy residues after its use as lubricant in machining machines.

Example 1: Preparation of the Lubricating Compositions I1, C1 and C2

An aqueous lubricating composition according to the invention (I1) and two comparative aqueous lubricating compositions, C1 not comprising polyalkylene glycol and C2 not comprising alkoxylated castor oil, were formulated according to the protocol below, in the percentages by weight shown in the following table 1.
The formulation protocol is as follows:
The alkoxylated castor oil is dissolved in the osmosed water. The solution is stirred at ambient temperature (close to 20° C.) for 30 minutes. At this stage, the solution may not be clear.
Then, the other components are added as follows: introduction of the additive(s) which is (are) regulator(s) of pH, then of the additive(s) which is (are) inhibitor(s) of corrosion while heating the mixture to a temperature of 40° C. to 50° C. The solution is stirred using a magnetic bar for a period of time ranging from 1 hour to 1 hour 30 minutes. The following compounds are subsequently added, sequentially every 5 minutes, in the following order and still with stirring: passivator(s), sequestering agent(s), PAG(s), then optionally wetting agent(s), antifoaming agent(s) and biocide(s).
Finally, a final stirring is carried out for a period of time of 1 hour.

TABLE 1

	I1 according to	C1 outside	C2 outside
Composition	the invention	the invention	the invention

Osmosed 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 corrosion inhibitors, passivators, sequestering agents, pH regulators, antifoaming agents and biocides.

Example 2: Characterization of the Composition According to the Invention and of the Comparative Compositions

The tribological properties were measured for each composition, as described in detail in the protocol above.
The results are compiled in table 2 below.

TABLE 2

	Dilution	Welding	Wear
Composition	ratio [%]	load [kg]	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

The composition I1 according to the invention exhibits a load at welding which is equivalent to that obtained for the comparative composition C2 and better than that obtained for the comparative composition C1, and a wear diameter of the same order of magnitude.
Thus, a lubricating composition in accordance with the invention, incorporating at least one polyalkylene glycol and alkoxylated castor oil, exhibits excellent extreme-pressure and antiwear properties which are equivalent to, indeed even better than, those obtained with a composition not comprising such a combination of ingredients.
Moreover, the gummy residues were quantified for each composition and the results are provided in table 3 below.

TABLE 3

	Variation in weight after	Water-insoluble
Composition	passage through the oven [%]	weight [mg]

I1 (Invention)	98.7	2.7
C1 (Comparative)	98.9	16.4
C2 (Comparative)	98.8	14.3

The composition I1 according to the invention exhibits a weight of insoluble compounds, corresponding to the gummy residues, which is significantly lower than those obtained for the comparative compositions C1 and C2.
Thus, a lubricating composition in accordance with the invention, combining at least one polyalkylene glycol and the alkoxylated, in particular ethoxylated, castor oil, advantageously makes it possible to result in significantly reduced amounts of gummy residues, after its use in the machining apparatus.

Example 3: Preparation of the Lubricating Composition I2

An aqueous lubricating composition according to the invention (I2) was formulated according to the protocol below, in the percentages by weight shown in the following table 4.
The formulation protocol is identical to that described in detail in example 1.

	TABLE 4

		I2 according to
	Composition	the invention

	Osmosed water [%]	51.01
	Polyalkylene glycol 2 [%]	10
	Ethoxylated castor oil [%]	10
	Additive(s)⁽¹⁾	28.99

	⁽¹⁾The additive(s) are chosen from corrosion inhibitors, passivators, sequestering agents, pH regulators, antifoaming agents and biocides.

Example 4: Characterization of the Composition According to the Invention

The tribological properties were measured for the composition I2 according to the invention, as described in detail in the protocol described above.
The results are compiled in table 5 below.

TABLE 5

	Dilution	Welding	Wear
Composition	ratio [%]	load [kg]	diameter [mm]

I2 (invention)	10	180	1.5-1.6

The composition I2 according to the invention exhibits a high load at welding. It furthermore has a low wear diameter.
Thus, a lubricating composition according to the invention, incorporating at least one polyalkylene glycol and alkoxylated castor oil, exhibits excellent extreme-pressure and antiwear properties.
Moreover, the gummy residues were quantified for the composition I2 according to the invention and the results are provided in table 6 below.

TABLE 6

	Variation in weight after	Water-insoluble
Composition	passage through the oven [%]	weight [mg]

I2 (invention)	96.8	0

The composition I2 according to the invention exhibits a zero weight of insoluble compounds, corresponding to the gummy residues.
Thus, a lubricating composition in accordance with the invention, combining at least one polyalkylene glycol and the alkoxylated, in particular ethoxylated, castor oil, advantageously makes it possible to result in significantly reduced amounts of gummy residues, after its use in the machining apparatus.

Claims

1-10. (canceled)

11. An aqueous lubricant composition for metalworking comprising, based on a total weight of the composition:

water;

from 0.1% to 15% by weight of at least one polyalkylene glycol; and

from 0.1% to 15% by weight of at least one alkoxylated castor oil.

12. The aqueous lubricant composition as claimed in claim 11, comprising from 50% to 90% by weight of osmosed water.

13. The aqueous lubricant composition of claim 11, comprising from 60% to 75% by weight of osmosed water.

14. The aqueous lubricant composition of claim 11, wherein the at least one polyalkylene glycol is chosen from copolymers comprising ethylene oxide, propylene oxide and/or butylene oxide monomers.

15. The aqueous lubricating composition of claim 11, comprising from 1% to 10% by weight of the at least one polyalkylene glycol.

16. The aqueous lubricant composition of claim 11, comprising from 2% to 5% by weight of the at least one polyalkylene glycol.

17. The aqueous lubricant composition of claim 11, wherein the at least one alkoxylated castor oil comprises an ethoxylated castor oil obtained by reacting castor oil and ethylene oxide, at a castor oil:ethylene oxide molar ratio of from 1:1 to 1:100.

18. The aqueous lubricant composition of claim 11, wherein the at least one alkoxylated castor oil comprises an ethoxylated castor oil obtained by reacting castor oil and ethylene oxide, at a castor oil:ethylene oxide molar ratio of 1:35.

19. The aqueous lubricant composition of claim 11, comprising from 1% to 10% by weight of the at least one alkoxylated castor oil.

20. The aqueous lubricant composition of claim 11, comprising from 2% to 5% by weight of the at least one alkoxylated castor oil.

21. The aqueous lubricant composition of claim 11, further comprising at least one additive chosen from antifoaming agents, biocides, pH regulators, corrosion inhibitors, antiwear and/or extreme-pressure additives, sequestering agents, metal passivating agents, dyes, dispersants, emulsifying agents, or mixtures thereof.

22. A method of forming a metal part, comprising:

applying an aqueous lubricant composition to a metal workpiece and/or a machining tool; and

machining the metal workpiece using machining apparatus to form a metal part, such that the aqueous lubricant composition reduces friction during the machining,

wherein the aqueous lubricant composition comprises, based on a total weight of the composition:

water;

from 0.1% to 15% by weight of at least one polyalkylene glycol; and

from 0.1% to 15% by weight of at least one alkoxylated castor oil.

23. The method of claim 22, wherein the aqueous lubricant composition comprises:

from 60% to 75% by weight of osmosed water;

from 2% to 5% by weight of at least one polyalkylene glycol; and

from 2% to 5% by weight of at least one ethoxylated castor oil.