Use of lubricant composition comprising at least one base oil and at least one fatty alcohol

Abstract

The invention relates to the use of a lubricant composition comprising at least one base oil and at least one saturated or unsaturated, linear or branched fatty alcohol comprising 8 to 20 carbon atoms for lubricating moving parts in screw compressors.

Description

Technical Field

[0001] The present invention relates to the field of lubricant compositions. These compositions can be used in various applications, in particular for lubricating various mechanical systems, in particular as screw compressor oils.

[0002] The present invention relates more particularly to the use of at least one specific fatty alcohol as an additive for improving the properties of a lubricant, such as the dispersancy properties, in other words the cleaning properties. Background Art

[0003] Lubricant compositions, also known as "lubricants," are commonly used in mechanical systems to reduce friction between components and thereby protect them from wear. Besides the phenomenon of wear, friction also impedes the relative movement between contacting components and leads to energy losses that are detrimental to the optimal operation of the mechanical system. To this end, lubricant compositions conventionally consist of a base oil to which a variety of additives are usually combined, which are specifically designed to stimulate the lubricating properties of the base oil and also to provide additional performance characteristics.

[0004] Lubricants are used in numerous applications, in particular in screw compressors, which are used, inter alia, in sectors such as automotive, brewing, food packaging, aerospace or construction.

[0005] Lubricants may encounter high temperatures during use. In the presence of oxygen, they oxidize and degrade. This degradation can lead to the formation of deposits, varnish, and sludge, an increase in lubricant viscosity, an increase in lubricant acidity, or a darkening of the lubricant.

[0006] The oxidation stability of lubricating oils is further reduced by the dissolution of metals in these oils, as dissolved metals can catalyze the oxidative degradation of the lubricant.

[0007] This degradation results in a loss of the lubricant's original performance characteristics, which may affect the correct operation of the mechanical system. Lubricants can also become contaminated during use due to contact with impurities.

[0008] These various degradation and contamination phenomena therefore lead to a reduction in the cleanliness of the lubricant and the mechanical parts that come into contact with the lubricant. Therefore, it becomes necessary to replace the lubricant after a certain period of use.

[0009] Improving the dispersancy properties of lubricants when used in mechanical systems (and in particular reducing the formation of deposits and varnish) is therefore an important lever for extending the service life, oil change intervals and maintenance intervals of the lubricant.

[0010] Therefore, limiting or even preventing the degradation of the lubricant composition also makes it possible to reduce the carbon impact due to the use of smaller amounts of lubricant composition.

[0011] To limit lubricant degradation during lubrication (and in particular to reduce deposit and varnish formation), lubricants typically use high-quality base oils such as polyalphaolefins (PAO) or high-solubility oils such as esters, alkylated naphthalenes, naphthenic oils or alkylbenzenes.

[0012] However, these lubricants (particularly PAOs and esters) have high costs, which hinders their use, especially as oils with a service life of 4,000 hours. Furthermore, high-solubility lubricants are not always effective in maintaining dispersion properties.

[0013] Finding additive systems that improve lubricant dispersancy performance, particularly reducing the formation and / or presence of deposits and varnish, remains an ongoing focus to optimize lubricant service life and extend oil change and maintenance intervals.

[0014] Lubricant compositions containing fatty alcohols to improve the cleanliness of four-stroke vehicle engines are described in FR 3 066 200 A1. However, these compositions are not suitable for use in screw compressors, particularly in view of the environmental differences specific to each application (e.g., whether the fuel is mixed with the oil or not, or temperature differences), or differences in the desired functionality.

[0015] In practical terms, for an engine, the composition must lubricate and cool the engine's components, while also recovering kinetic energy. In the case of a screw air compressor, it's the compressed air that's being recovered, and this compressed air must remain clean and uncontaminated. Therefore, the lubricant composition used must possess unique properties, otherwise there's a risk of clogging the entire system.

[0016] Thus, for example, lubricant compositions for engines contain very high levels of detergents which are not suitable for lubricants for screw compressors since this would clog the entire device and contaminate it. Summary of the Invention

[0017] Summary of the Invention

[0018] The present invention is particularly directed to providing a novel additive system for lubricating moving parts in screw compressors.

[0019] More particularly, the present invention aims to provide a novel additive system for improving cleanliness during lubrication in screw compressors and, in particular, for improving the maintenance of the dispersibility of compositions used to lubricate moving parts in screw compressors.

[0020] Thus, according to its first aspect, the present invention relates to the use of a lubricant composition comprising at least one base oil and at least one saturated or unsaturated, linear or branched fatty alcohol comprising 8 to 20 carbon atoms for lubricating moving parts in screw compressors.

[0021] The present invention also relates to the use of at least one saturated or unsaturated, linear or branched fatty alcohol containing 8 to 20 carbon atoms in a lubricant composition comprising at least one base oil for improving the properties of said composition for use in screw compressors, and in particular for improving the retaining dispersion properties ("keep-clean" properties) of said composition for use in screw compressors.

[0022] In the remainder of the text, the fatty alcohols as defined above will according to the invention be more simply referred to by the term "fatty alcohols".

[0023] Surprisingly, the inventors have found that the addition of at least one fatty alcohol according to the invention to a lubricant composition makes it possible to significantly improve the performance of this composition in terms of dispersancy properties.

[0024] In particular, as shown in the examples hereinafter, the inventors have demonstrated that the presence of at least one fatty alcohol according to the invention in a lubricant composition makes it possible to reduce or even prevent the formation of deposits and varnishes.

[0025] Thus, by adding at least one fatty alcohol according to the invention, the service life of the lubricant composition can be increased, in particular in screw compressors, to an operating time of at least 2000 hours, in particular at least 4000 hours, in particular at least 8000 hours, or at least 12000 hours, while maintaining the required lubricating properties of these compressors.

[0026] The interval between two successive oil changes of the screw compressor can thus be increased.

[0027] Moreover, it has been surprisingly and advantageously found that the present invention, thanks to the use of at least one saturated or unsaturated, linear or branched fatty alcohol containing from 8 to 20 carbon atoms, makes it possible to dispense with the ester compounds conventionally used in lubricant compositions containing high-quality base oils such as polyalphaolefins (PAOs).

[0028] According to another aspect, the present invention also relates to a method for reducing deposit or varnish formation when lubricating a screw compressor using a lubricant composition comprising at least one base oil, the method comprising adding to the lubricant composition at least one saturated or unsaturated, linear or branched fatty alcohol containing 8 to 20 carbon atoms.

[0029] The present invention also relates to a method for lubricating a screw compressor, comprising the step of contacting at least one component of said screw compressor with a lubricant composition comprising at least one base oil and at least one saturated or unsaturated, linear or branched fatty alcohol containing 8 to 20 carbon atoms.

[0030] Further characteristics, variants and advantages of the use of at least one fatty alcohol according to the invention will become clearer on reading the following description and the examples, which are given by way of illustration and do not limit the invention.

[0031] The expressions “between . . . and . . ,” “from . . . to . . ,” “formed from . . . to . ,” and “varying from . . . to . . ” are to be understood as including the boundary values, unless otherwise indicated.

[0032] Detailed instructions

[0033] fatty alcohols

[0034] As mentioned above, the fatty alcohols used are saturated or unsaturated, linear or branched fatty alcohols containing 8 to 20 carbon atoms.

[0035] The composition may thus contain a single fatty alcohol according to the invention or a plurality of different fatty alcohols. If a plurality of different fatty alcohols are present, they can be added separately during the preparation of the lubricant composition and a mixture thereof can subsequently be formed in situ. They can also be used in the form of commercially available mixtures.

[0036] Preferably, the one or more fatty alcohols have a flash point of at least 80°C, or even at least 100°C.

[0037] In particular, the one or more fatty alcohols have a melting point lower than or equal to 15°C.

[0038] Preferably, the one or more fatty alcohols are liquid.

[0039] The fatty alcohol(s) may be chosen from saturated or unsaturated, linear or branched fatty alcohols comprising from 8 to 20 carbon atoms, preferably from 12 to 20 carbon atoms.

[0040] The fatty alcohol(s) are chosen in particular from saturated linear or branched fatty alcohols comprising from 8 to 20 carbon atoms, preferably from 12 to 20 carbon atoms.

[0041] In particular, the fatty alcohol(s) are chosen from saturated linear fatty alcohols comprising 8 to 20 carbon atoms, preferably 12 to 18 carbon atoms, or even 12 to 14 carbon atoms, or saturated branched fatty alcohols comprising 14 to 20 carbon atoms, preferably 16 to 20 carbon atoms, which are especially branched only in the beta position relative to the alcohol function.

[0042] In particular, the one or more fatty alcohols are chosen from decanol (also known as octan-1-ol, CAS No. 111-87-5), lauryl alcohol (also known as dodecan-1-ol, CAS No. 112-53-8), palmityl alcohol (also known as hexadecan-1-ol), myristyl alcohol (also known as tetradecan-1-ol, CAS No. 112-72-1), stearyl alcohol (also known as octadecane-1-ol, CAS No. 112-92-5), 2-hexyldecanol (also known as 2-hexyl-1-decanol, CAS No. 2425-77-6), 2-octyldodecanol (also known as 2-octyl-1-dodecanol, CAS No. 5333-42-6) and mixtures thereof, preferably chosen from lauryl alcohol, 2-hexyldecanol, 2-octyldodecanol and mixtures thereof.

[0043] The fatty alcohol may be in the form of a mixture of different fatty alcohols, for example a mixture of lauryl alcohol and myristyl alcohol.

[0044] The lubricant composition may have a content of said one or more fatty alcohols of less than or equal to 10% by weight, in particular from 0.01% to 10% by weight, more particularly from 0.02% to 8% by weight, preferably from 0.05% to 5% by weight, more preferably from 0.1% to 1% by weight, relative to the total weight of the lubricant composition.

[0045] In particular, the lubricant composition may have a content of the one or more fatty alcohols of 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.% or 0.9 wt.%, relative to the total weight of the lubricant composition.

[0046] Lubricant composition

[0047] base oil

[0048] The lubricant composition used according to the invention comprises at least one base oil.

[0049] The base oil may be chosen from the base oils conventionally used in the field of lubricant compositions, such as mineral oils, synthetic oils or natural animal or vegetable oils, at least partially rerefined oils or mixtures thereof.

[0050] This may be a mixture of various base oils, for example a mixture of two, three or four base oils.

[0051] In the context of the present invention, the expression "at least partially rerefined oil" (also referred to more simply as "rerefined oil", "reclaimed oil" or "recycled oil" in the remainder of the text) refers to an oil that is at least partially obtained from a used lubricant composition that has undergone one or more known processing steps, such as a rerefining process.

[0052] According to the present invention, a "used lubricant composition" (or more simply "used lubricant" or "used lubricating oil") refers to any lubricant composition that has been used to lubricate moving parts (especially metal parts) of a mechanical system (such as but not limited to bearings, gear mechanisms or engines).

[0053] The used lubricant may come from various sources. In particular, as described in detail in the remainder of this document, it may be a lubricant that has been used to lubricate motorized systems, in particular "mobile" systems, or that has been used to lubricate industrial systems, in particular "stationary" systems.

[0054] Considering its origin, used lubricating oils, in particular engine lubricating oils, contain a certain amount of degradation products derived from the oil itself or the additives contained therein, as well as metal particles, metal oxides and other elements, for example from the engine. Used oils may contain, in particular, high levels of undesirable elements such as calcium (Ca), iron (Fe), magnesium (Mg), sodium (Na), nickel (Ni), phosphorus (P), silicon (Si), chlorine (Cl), zinc (Zn), etc.

[0055] Processes have been developed for refining or reconditioning used lubricating oils in order to regenerate these oils and permit their subsequent reuse.

[0056] Rerefined lubricating oils are therefore oils obtained from one or more treatment steps of used lubricants aimed at removing at least partially a certain number of contaminating components present therein, such as dust, water, fuel fractions, metallic elements and other residues resulting from the degradation of additives present in the lubricant.

[0057] The base oil of the lubricant composition under consideration according to the invention may especially be an oil of mineral or synthetic origin belonging to groups I to V according to the categories defined in the API classification (as shown in Table 1 below) (or their equivalents according to the ATIEL classification), or a mixture thereof.

[0058]

[0059] Table 1

[0060] Mineral base oils include all types of base oils obtained by atmospheric and vacuum distillation of crude oil followed by refining operations such as solvent extraction, deasphalting, solvent deparaffinization, hydrotreating, hydrocracking, hydroisomerization and hydrofinishing.

[0061] Synthetic base oils may be esters of carboxylic acids and alcohols, polyalphaolefins or polyalkylene glycols (PAGs) obtained by polymerization or copolymerization of alkylene oxides containing 2 to 8 carbon atoms, in particular 2 to 4 carbon atoms. The polyalphaolefins used as base oils are obtained, for example, from monomers containing 4 to 32 carbon atoms (for example from decene, octene or dodecene) and have a viscosity at 100° C. of 1.5 to 150 mm² according to standard ASTM D445. 2 .s -1 Their average molecular weight according to ASTM D5296 is generally 250-3000.

[0062] In particular, the lubricant composition may comprise at least one base oil selected from polyalphaolefins, esters of carboxylic acids and alcohols, and mixtures thereof.

[0063] Mixtures of mineral oils and synthetic oils, which may be of biological origin, may also be used.

[0064] There are generally no restrictions on the use of different base oils in the lubricant composition, except that they must have properties, in particular viscosity, viscosity index or sulphur content, suitable for the intended use, in particular for use in screw compressors.

[0065] In particular, the base oil is chosen from the oils of Group I, Group II, Group III, Group IV and Group V of the API classification, more particularly from the oils of Group II and Group III of the API classification and mixtures thereof, more preferably from the oils of Group II.

[0066] Preferably, the lubricant composition comprises 80% to 99.5% by weight, in particular 90% to 99% by weight, preferably 95% to 99% by weight, of one or more base oils, preferably selected from Group II base oils, Group III base oils, Group IV base oils, Group V base oils and mixtures thereof, preferably selected from Group II base oils, relative to the total weight of the lubricant composition.

[0067] For example, the lubricant composition comprises 80% to 99.5% by weight, in particular 90% to 99% by weight, preferably 95% to 99% by weight of one or more base oils selected from Group II base oils, mixtures of Group II base oils and Group III base oils, and Group IV base oils, preferably selected from Group II base oils.

[0068] Advantageously, the presence of at least one fatty alcohol according to the invention makes it possible to reduce or even dispense with the use of high-quality oils such as PAO oils, while maintaining the excellent performance qualities of the compositions comprising them, in particular in terms of dispersancy properties.

[0069] Preferably, the lubricant composition comprises 80% to 99.5% by weight, in particular 90% to 99% by weight, preferably 95% to 99% by weight, of one or more base oils selected from Group II base oils and / or Group III base oils, preferably Group II base oils, relative to the total weight of the lubricant composition.

[0070] The inventors have shown that the addition of at least one fatty alcohol according to the invention to a Group II base oil advantageously enables the compositions comprising it to achieve performance qualities, in particular in terms of maintaining dispersancy properties, which are as good as mixtures of Group II and Group III base oils.

[0071] It has also been shown that the presence of fatty alcohols in lubricant compositions comprising Group IV or Group V base oils (ie, high quality oils) also enables improved maintenance of the dispersancy properties of the lubricant composition.

[0072] According to a particular embodiment, the lubricant composition may comprise a group IV or group V base oil, in particular a group IV base oil, in particular in a content of 80% to 99.5% by weight, in particular 90% to 99% by weight, preferably 95% to 99% by weight relative to the total weight of the lubricant composition.

[0073] The inventors have shown that the addition of at least one fatty alcohol according to the invention to a Group IV base oil advantageously enables the composition comprising it to achieve performance qualities, in particular in terms of maintaining dispersancy properties, which are at least as good as mixtures of Group IV and Group V base oils.

[0074] In particular, the base oil suitable for the present invention may have a kinematic viscosity of 11 mm2 measured at 40° C. according to standard ASTM D445 (KV40). 2 / s to 1600mm 2 / s.

[0075] In particular, the base oil as described above may be present in the lubricant composition according to the invention in a content of at least 80% by weight, in particular at least 90% by weight, more particularly 80% to 99.5% by weight, in particular 90% to 99% by weight, preferably 95% to 99% by weight, relative to the total weight of the composition.

[0076] additive

[0077] The lubricant composition according to the invention may also contain any type of additives suitable for the intended use of the lubricant.

[0078] All additional additives may be included in the form of an additive mixture or "pack," or may be introduced individually during formulation of the composition.

[0079] The fatty alcohols used according to the invention can be added in combination with one or more additives, in particular as a mixture with an additive package, or else alone.

[0080] In a particular embodiment, the additional additive may represent 0.1% to 30% by weight, in particular 0.5% to 20% by weight, especially 1% to 15% by weight, more preferably 2% to 10% by weight, preferably 2% to 5% by weight, even more preferably 2% to 3% by weight relative to the total weight of the composition.

[0081] It is to be understood that the content of additional additives does not include the content of fatty alcohol according to the present invention.

[0082] In particular, the lubricant composition used according to the present invention comprises one or more additional additives selected from the group consisting of additives selected from anionic compounds comprising a lipophilic long hydrocarbon chain and a hydrophilic head, friction modifiers, antiwear additives, extreme pressure additives, antioxidants, viscosity index (VI) improvers, pour point depressant (PPD) additives, dispersants, defoamers, demulsifiers, thickeners, corrosion inhibitors, metal deactivators, cycloparaffinic solvents and mixtures thereof.

[0083] It will be appreciated that the nature and amount of additional additives used are chosen so as not to adversely affect the properties of the lubricant composition, in particular the performance qualities imparted by the fatty alcohol used according to the invention.

[0084] In particular, the lubricant composition used according to the present invention comprises one or more additional additives selected from anionic compounds comprising a lipophilic long hydrocarbon chain and a hydrophilic head, antiwear additives, extreme pressure additives, antioxidants, pour point depressant (PPD) additives, defoamers, demulsifiers, corrosion inhibitors, metal deactivators, naphthenic solvents and mixtures thereof.

[0085] Preferably, the lubricant composition used according to the invention comprises one or more additional additives selected from antiwear additives, extreme pressure additives, antioxidants, pour point depressant (PPD) additives, defoamers, demulsifiers, corrosion inhibitors and metal passivators.

[0086] Preferably, the lubricant composition used according to the invention does not contain friction modifier additives.

[0087] According to the invention, the fatty alcohols used are not friction modifier additives.

[0088] Preferably, the lubricant composition used according to the invention does not comprise a thickener.

[0089] According to a particular embodiment, the lubricant composition used according to the invention comprises less than 1%, in particular less than 0.1%, more preferably less than 0.01% by weight of detergent additives different from the fatty alcohol used, relative to the total weight of the composition, or even contains no detergent additives different from the fatty alcohol used.

[0090] Preferably, the composition according to the invention does not contain detergent additives other than the fatty alcohol used.

[0091] Preferably, the lubricant composition according to the invention comprises at least one antiwear additive, an extreme pressure additive or a mixture thereof.

[0092] Antiwear additives and extreme pressure additives are specifically designed to protect surfaces subject to friction by forming a protective film that is adsorbed onto these surfaces. A wide variety of antiwear additives exists. Antiwear additives that are particularly suitable for the present invention are selected from polysulfide additives, sulfur-containing olefin additives, phosphorus-sulfur additives, amine phosphates, and mixtures thereof, with amine phosphates being preferred.

[0093] According to a particular embodiment, the lubricant composition according to the invention may comprise 0.01-6% by weight, in particular 0.05-4% by weight, preferably 0.1-2% by weight and more preferably 0.1-1% by weight of antiwear additives and extreme pressure additives relative to the total weight of the composition.

[0094] According to one particular embodiment, the lubricant composition according to the invention may comprise at least one antioxidant additive.

[0095] The antioxidant additive makes it possible to retard the degradation of the lubricant composition in use. The antioxidant additive acts in particular as a free radical inhibitor or hydroperoxide destroyer.

[0096] Among the commonly used antioxidant additives, phenolic antioxidants, amine antioxidant additives, phosphorus-sulfur antioxidant additives can be mentioned. Some of these antioxidant additives (for example, phosphorus-sulfur antioxidant additives) can produce ash. Phenolic antioxidant additives can be ashless or can be in the form of neutral or alkaline metal salts. The antioxidant additive can be selected in particular from sterically hindered phenols, sterically hindered phenol esters and sterically hindered phenols containing thioether bridges, diphenylamines and sterically hindered phenols containing at least one C1-C 12 Alkyl group-substituted diphenylamines, N,N'-dialkylaryldiamines, and mixtures thereof.

[0097] Preferably, the sterically hindered phenol is selected from compounds comprising a phenol group in which at least one carbon adjacent to the carbon bearing the alcohol function is replaced by at least one C1-C 10The amine compounds are another class of antioxidant additives that can be used, which are optionally used in combination with phenolic antioxidant additives. Examples of amine compounds are aromatic amines, such as those of formula NR 5 R 6 R 7 Aromatic amines, where R 5 represents an optionally substituted aliphatic or aromatic group, R 6 represents an optionally substituted aromatic group, R 7 represents a hydrogen atom, an alkyl group, an aryl group or a group of formula R 8 S(O) z R 9 A group in which R 8 represents an alkylene group or an alkenylene group, R 9 represents an alkyl group, an alkenyl group or an aryl group and z represents 0, 1 or 2. Sulfurized alkylphenols or alkali metal and alkaline earth metal salts thereof can also be used as antioxidant additives.

[0098] According to a particular embodiment, the lubricant composition according to the invention comprises from 0.1% to 3% by weight, preferably from 0.5% to 2% by weight, of at least one antioxidant additive relative to the total weight of the composition.

[0099] According to a particular embodiment, the lubricant composition used according to the invention comprises less than 1%, in particular less than 0.1%, more preferably less than 0.01% by weight of sulfur-containing additives relative to the total weight of the composition, or even no sulfur-containing additives. The lubricant composition used according to the invention may also comprise at least one additive chosen from anionic compounds comprising a lipophilic long hydrocarbon chain and a hydrophilic head.

[0100] According to one particular embodiment, the lubricant composition used according to the invention may also comprise at least one pour point depressant additive (also known as a “PPD” agent).

[0101] Pour point depressants generally improve the low temperature properties of the lubricant compositions of the present invention by slowing the formation of wax crystals.Examples of pour point depressants include polyalkyl methacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, and alkylated polystyrenes.

[0102] The lubricant composition according to the invention may comprise from 0.05% to 2% by weight, preferably from 0.1% to 1% by weight, of pour point depressants relative to the total weight of the composition.

[0103] The lubricant composition used according to the invention may also comprise at least one dispersant.

[0104] The dispersant may be selected from Mannich bases, succinimide and its derivatives, such as polyisobutylene succinic anhydride derivatives.

[0105] Preferably, the lubricant composition used according to the invention contains no dispersants.

[0106] The lubricant composition used according to the invention may also comprise at least one viscosity index (VI) improver additive.

[0107] Preferably, the lubricant composition used according to the present invention contains no viscosity index (VI) improver additives.

[0108] The lubricant composition used according to the invention may also comprise at least one antifoaming additive, for example chosen from polar polymers such as polymethylsiloxanes or polyacrylates.

[0109] In particular, the lubricant composition according to the invention may comprise from 0.001% to 1% by weight of antifoaming additive relative to the total weight of the composition.

[0110] It may also contain at least one corrosion inhibitor or metal passivator, for example a compound such as polyisobutylene succinic anhydride, thiadiazole sulfonates, mercaptobenzothiazole, alkyl phosphites or alkylaminoacetic acids.

[0111] They are typically present in the lubricant composition of the invention in a content ranging from 0.01% to 1% by weight relative to the total weight of the composition.

[0112] The lubricant composition used according to the invention may also contain an alcoholic or non-alcoholic aromatic or non-aromatic solvent, and in particular a naphthenic solvent. This naphthenic solvent allows the use of various additives in the form of a mixture or package of additives in the naphthenic solvent, which can then be introduced into the base oil during the formulation of the composition.

[0113] In particular, the lubricant composition according to the invention may comprise from 0.01% to 5% by weight, preferably from 0.1% to 3% by weight, or from 0.5% to 2% by weight of solvents, in particular cycloparaffinic solvents, relative to the total weight of the composition.

[0114] According to a particular embodiment, the lubricant composition used according to the invention comprises less than 1% by weight, in particular less than 0.1% by weight, more particularly less than 0.01% by weight of solvents, in particular cycloparaffinic solvents, relative to the total weight of the composition, or is even free of solvents, in particular cycloparaffinic solvents.

[0115] For the formulation of the lubricant compositions used according to the invention, the fatty alcohols under consideration according to the invention can be added alone to the base oil or base oil mixture, optionally followed by further additional additives.

[0116] The additional additives may be added individually or in the form of a mixture of one or more additional additives.

[0117] Alternatively, the fatty alcohol may be added to a pre-existing lubricant formulation comprising, inter alia, one or more base oils and additional additives.

[0118] Additional additives may be added individually or in the form of a mixture of one or more additional additives to form a pre-existing lubricant formulation.

[0119] The pre-existing formulation may also be a lubricant formulation that is already commercially available.

[0120] The fatty alcohols may also be formulated into an additive package in combination with one or more additional additives. The additive package mixture thus formed may then be introduced into a base oil or base oil blend.

[0121] According to one particular embodiment, the lubricant composition used according to the invention may comprise, or even consist of:

[0122] - a base oil or base oil mixture, in particular as defined above;

[0123] - one or more fatty alcohols according to the invention, in particular as defined above;

[0124] - Optionally, one or more additives different from the fatty alcohol, in particular chosen from anionic compounds comprising a lipophilic long hydrocarbon chain and a hydrophilic head, antiwear additives, extreme pressure additives, antioxidants, pour point depressant (PPD) additives, defoamers, demulsifiers, corrosion inhibitors, metal deactivators, solvents, in particular cycloparaffinic solvents, and mixtures thereof.

[0125] Preferably, the lubricant composition formulated according to the present invention comprises, or even consists of:

[0126] - 80% to 99.5% by weight, in particular 90% to 99% by weight, preferably 95% to 99% by weight, of one or more base oils, in particular selected from Group II, Group III and Group IV base oils and mixtures thereof, in particular Group II and Group III base oils and mixtures thereof, in particular Group II base oils;

[0127] - 0.01% to 10% by weight, preferably 0.02% to 8% by weight, more particularly 0.05% to 5% by weight, more preferably 0.1% to 1% by weight of one or more fatty alcohols, in particular as defined above, especially chosen from decanol, lauryl alcohol, 2-hexyldecanol, 2-octyldodecanol and mixtures thereof;

[0128] - 0.1% to 30% by weight, preferably 1% to 15% by weight, more preferably 1% to 5% by weight of one or more additives selected from anionic compounds containing a lipophilic long hydrocarbon chain and a hydrophilic head, antiwear additives, extreme pressure additives, antioxidants, pour point depressant (PPD) additives, defoamers, demulsifiers, corrosion inhibitors, metal deactivators, solvents, in particular cycloparaffinic solvents, and mixtures thereof;

[0129] The content is expressed relative to the total weight of the lubricant composition.

[0130] According to a particular embodiment, the lubricant composition according to the invention has a kinematic viscosity of 20 mm2, measured at 40° C. according to standard ASTM D445. 2 / s to 800mm 2 / s, preferably 20mm 2 / s to 200mm 2 / s.

[0131] application

[0132] The lubricant composition used according to the invention can be used for lubricating moving parts in any type of mechanical system, in particular for gas turbines or steam turbines in the aviation, marine, rail transport and power generation sectors, for compressors (in particular screw compressors), which are used in particular in sectors such as automotive, brewing, food packaging, aerospace or construction, for wind power plants, in particular for generating electrical energy, for hydraulic systems, etc.

[0133] According to the invention, the composition according to the invention is used for lubricating moving parts in screw compressors, in particular for producing compressed air.

[0134] Advantageously, thanks to the present invention, the retention of the dispersancy properties of the lubricant composition is improved.

[0135] Therefore, the lubricant composition can be used more particularly for maintaining the cleanliness of screw compressors.

[0136] Maintaining the dispersancy properties of a lubricant composition and thus maintaining the cleanliness of a mechanical system is often referred to as a "keep clean" technique.

[0137] It is thus intended to denote the fact that the lubricant composition used produces little or no deposits, varnish or any other residue on the surfaces of the moving parts of the mechanical system or in the lubricant composition, in particular during use of the lubricant composition to lubricate the mechanical system.

[0138] The dispersibility of the lubricant composition can be evaluated by testing according to a modified ASTM D7873 standard, for example by visual observation of oxygen bubbling in the lubricant composition in the presence of a copper and steel based catalyst at 140° C., or by testing according to JIS K2514 at 165° C., as shown in the Examples.

[0139] For example, the lubricant composition contemplated according to the present invention may be added to a mechanical system after draining out the spent lubricant formulation to maintain the cleanliness of the mechanical system.

[0140] In particular, the lubricant composition contemplated by the present invention can be used to reduce the formation of deposits and / or varnish in the screw compressor. The screw compressor can thus remain cleaner for a longer period of time, and its degradation can be slowed down. In particular, the lubricant composition contemplated by the present invention can be used to reduce the frequency of cleaning and replacement of components of the screw compressor. In particular, the lubricant composition contemplated by the present invention can be used to extend the interval between two consecutive maintenance operations on the screw compressor.

[0141] The fatty alcohols according to the invention can also be used in lubricant compositions comprising at least one base oil in order to improve the properties of said compositions used in screw compressors.

[0142] In particular, the fatty alcohols according to the present invention can be used to improve the retention of the dispersing properties of the composition used in screw compressors.

[0143] More specifically, the fatty alcohols according to the invention can be used to slow down or even prevent the degradation of lubricant compositions during the lubrication of moving parts in screw compressors, in particular by reducing the formation of deposits and / or varnish in the lubricant composition, especially when lubricating moving parts in screw compressors. The fatty alcohols according to the invention can be used in particular to maintain the lubricating properties of the lubricant composition during its use. The fatty alcohols according to the invention thus make it possible to increase the service life of the lubricant composition while maintaining high lubricating properties.

[0144] In particular, the fatty alcohol can be used to increase the service life of the lubricant composition as described above in the screw compressor. In particular, the use of the fatty alcohol makes it possible to extend the interval between two consecutive oil changes of the screw compressor.

[0145] Preferably, the interval between two consecutive oil changes may be at least 2000 hours, preferably at least 4000 hours, more preferably at least 8000 hours, or even at least 12000 hours of operation of the screw compressor.

[0146] The lubricant composition contemplated by the present invention can be used to lubricate moving parts in a screw compressor, in particular, to lubricate the rotating screw of the screw compressor. In particular, the mechanical system is a screw compressor for producing compressed air. The mechanical system can be an oil-injected screw compressor. The screw compressor can be used in a variety of applications, such as in the automotive, brewing, food packaging, aerospace, or construction sectors.

[0147] All features and special embodiments related to the fatty alcohol and the lubricant composition comprising it also apply to the uses and methods targeted according to the present invention. DETAILED DESCRIPTION

[0148] The present invention will now be described by way of the following examples, which are given by way of illustration and are not meant to limit the present invention in any way.

[0149] Example

[0150] Measuring performance in terms of cleanliness

[0151] The performance of the lubricant composition in terms of cleanliness is evaluated by a test according to a modified ASTM 7873 standard (“TOST”, an acronym for “Thermal Oxidation Stability Test”), which is modified as follows:

[0152] A lubricant composition was heated to 140°C in a glass container placed in an oil bath in the presence of a copper-steel catalyst. Oxygen was bubbled through the lubricant composition, maintained at 140°C, for 168 hours. At the end of the test, the container was visually observed. The presence and appearance of deposits and / or varnish on the glass surface were noted. The appearance of the catalyst was also observed. A sample of the composition obtained at the end of the test was filtered through a filter to remove particles larger than 1 μm. The color of the filtered particles was noted.

[0153] The resulting filtered particles and the visual appearance of the glass containers enabled the evaluated lubricant compositions to be classified for their performance in maintaining cleanliness:

[0154] 0 The glass container is covered with opaque black sediment and / or varnish, and the filtered particles are black / very dark brown;

[0155] + The glass container is covered with a somewhat transparent black / dark brown sediment and / or varnish, and the filtered particles are black / dark brown;

[0156] ++The glass container is covered with a transparent black sediment and / or varnish, and the filtered particles are black / dark brown;

[0157] +++The glass container is covered with a light transparent sediment and / or varnish, and the filtered particles are black / dark brown;

[0158] ++++No sediment was visible on the surface of the glass container, and the filtered particles were yellow / light beige.

[0159] Preparation and evaluation of compositions according to the present invention and comparative compositions

[0160] Lubricant compositions according to the invention (I1 to I16) and comparative lubricant compositions (C1 to C5) were formulated by adding a concentrate of the additives to a solvent or by adding each additive individually (i.e., in the absence of a solvent) in the weight percentages shown in the table below. The percentages are expressed by weight relative to the total weight of the composition.

[0161] The additive is a mixture of additives comprising one or more antioxidant additives, pour point depressants, extreme pressure additives, anti-wear additives, corrosion inhibitors, one or more metal passivators, one or more demulsifiers and / or one or more anti-foam additives.

[0162] The composition of the additive mixture is the same for the following compositions: compositions C1 and I1 to I7; compositions C2 and I11; compositions I8 to I10; compositions C3, I12 and I13; and compositions C5, I15 and I16.

[0163] The lubricant compositions were evaluated for cleanliness performance according to the TOST test described above. The following table summarizes the classification of each composition.

[0164]

[0165] Table 2

[0166] Composition C2 I8 I9 I10 I11 Group II base oil [%] 96.5 96 96 94.5 91.5 Solvent [%] 0.7 0.97 0.97 0.97 0.7 additive[%] 2.8 2.53 2.53 2.53 2.8 <![CDATA[2-Hexyldecanol (C 16 ) [%]]]> - - 0.5 - - <![CDATA[2 - Octyldodecanol (C 20 ) [%]]]> - 0.5 - 2 5 Cleanliness performance 0 ++ ++ ++++ +

[0167] Table 3

[0168] Composition C3 I12 I13 Group II base oil [%] 98.18 93.18 93.18 additive[%] 1.82 1.82 1.82 <![CDATA[2-Hexyldecanol (C 16 ) [%]]]> - - 5 <![CDATA[2 - Octyldodecanol (C 20 ) [%]]]> - 5 - Cleanliness performance 0 + +

[0169] Table 4

[0170] Composition C4 I14 Group II base oil [%] 100 98 <![CDATA[2 - Octyldodecanol (C 20 )]]> - 2 Cleanliness performance + ++++

[0171] Table 5

[0172]

[0173] Table 6

[0174] It was observed that the compositions according to the invention comprising a fatty alcohol according to the invention showed a higher degree of cleaning at the end of the test than the compositions without fatty alcohol.

[0175] Comparison of compositions 12 and 110 also demonstrates that compositions comprising a Group II base oil and a fatty alcohol of the present invention, but without a Group III base oil, can achieve similar cleanliness performance as compared to similar compositions further comprising a Group III base oil.

[0176] Comparison of compositions C5 and 116 also demonstrates that compositions comprising a Group IV base oil and a fatty alcohol of the present invention, but not a Group V base oil, can achieve greater cleanliness performance than similar compositions further comprising a Group V base oil.

[0177] Two tests were also carried out according to Japanese Standard JIS K2514 ("ISOT test", acronym for "Indiana Stirring Oxidation Test") which confirmed the results detailed above.

Claims

1. Use of a lubricant composition comprising at least one base oil and at least one saturated or unsaturated, linear or branched fatty alcohol containing 8 to 20 carbon atoms for lubricating moving parts in screw compressors.

2. The method of claim 1, wherein the one or more fatty alcohols are selected from the group consisting of decyl alcohol, lauryl alcohol, palmityl alcohol, myristyl alcohol, stearyl alcohol, 2-hexyldecanol, 2-octyldodecanol, and mixtures thereof, preferably selected from the group consisting of lauryl alcohol, 2-hexyldecanol, 2-octyldodecanol, and mixtures thereof.

3. The use as claimed in any one of the preceding claims, wherein the lubricant composition has a content of the one or more fatty alcohols of less than or equal to 10% by weight, in particular from 0.01% to 10% by weight, more in particular from 0.02% to 8% by weight, preferably from 0.05% to 5% by weight, more preferably from 0.1% to 1% by weight, relative to the total weight of the lubricant composition.

4. The use according to any one of the preceding claims, wherein the lubricant composition comprises 80% to 99.5% by weight, in particular 90% to 99% by weight, preferably 95% to 99% by weight, relative to the total weight of the lubricant composition, of one or more base oils, preferably selected from Group II base oils, Group III base oils, Group IV base oils, Group V base oils and mixtures thereof, preferably selected from Group II base oils and / or Group III base oils, more preferably selected from Group II base oils.

5. The use as claimed in any one of the preceding claims, wherein the lubricant composition comprises at least one base oil selected from polyalphaolefins, esters of carboxylic acids and alcohols and mixtures thereof.

6. The use according to any one of the preceding claims, wherein the lubricant composition further comprises one or more additional additives selected from anionic compounds comprising a lipophilic long hydrocarbon chain and a hydrophilic head, anti-wear additives, extreme pressure additives, antioxidants, pour point depressant (PPD) additives, defoamers, demulsifiers, corrosion inhibitors, metal deactivators, cycloparaffinic solvents and mixtures thereof.

7. The use as claimed in any one of the preceding claims, wherein the screw compressor is a screw compressor for producing compressed air.

8. Use as claimed in any one of the preceding claims for reducing the formation of deposits and / or varnish in the screw compressor.

9. Use of at least one saturated or unsaturated, linear or branched fatty alcohol comprising 8 to 20 carbon atoms in a lubricant composition comprising at least one base oil for improving the properties of said composition when used in a screw compressor.

10. Use according to the preceding claim for improving the dispersion-maintaining properties of the composition used in screw compressors.

11. The method according to claim 9 or 10, for increasing the service life of the composition in the screw compressor, in particular for extending the interval between two consecutive oil changes of the screw compressor, more particularly such that the interval between two consecutive oil changes of the screw compressor is at least 2000 hours, preferably at least 4000 hours, more preferably at least 8000 hours, or even at least 12000 hours of operation of the screw compressor.

12. The use according to any one of claims 9 to 11, wherein the one or more fatty alcohols, the one or more base oils, the screw compressor and / or the composition are as defined in any one of claims 1 to 7.

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