Lubricant composition and use thereof

Abstract

The present invention relates to a biodegradable lubricant composition and its use as transmission oil, rolling bearing oil, hydraulic oil or sliding bearing oil in the marine field and in the field of fresh waters, as well as in on-shore machines and machine elements that may come in contact with water and / or aqueous media.

Description

[0001] The present invention relates to biodegradable lubricant compositions and their use as gear, rolling bearing, hydraulic and plain bearing oil in the marine sector and in inland waters, as well as in machines and machine elements on land that may come into contact with water and / or aqueous media.

[0002] When lubricants or lubricant compositions are used as gear oils, rolling bearing oils, hydraulic oils, and plain bearing oils in marine and inland waterways, i.e., applications where the lubricants or lubricant compositions are typically used below the waterline in oil-to-water interfaces, there is a risk of contamination of the marine or aquatic environments due to lubricant escape, caused, for example, by leaks. Although every effort is made to seal the water side in these applications as best as possible, lubricant losses are commonplace. Lubricants used in machines and machine elements on land, particularly in the mining industry, wind turbines, and agricultural machinery, can also come into contact with water, for example, due to rain.In addition, leaks often occur here, which can lead to environmental contamination and soil pollution by chemicals.

[0003] In recent years, environmental protection has become increasingly important, especially the protection of the oceans. This is demonstrated by various new legislations to protect the marine environment from pollution, which require the use of lubricants that are safe for the marine environment. For example, the Vessel General Permit (VGP) of the United States Environmental Protection Agency For lubricants used below the waterline, the use of so-called Environmentally Acceptable Lubricants (EALs), which must meet high requirements regarding biodegradability and aquatic toxicity.

[0004] The selection and usable quantity of base oil components and additives for a lubricant is therefore limited. Common EALs are therefore made from natural and synthetic esters, rather than the conventional mineral oil base. However, compared to mineral oil-based lubricants, the use of EALs frequently results in damage to sealing materials.

[0005] In the marine sector and in inland waters, as well as in machines and machine elements on land, radial shaft seals are generally used, which are usually made of elastomer materials such as FKM (fluororubber), NBR ( nitrile butadiene rubber ) , HNBR ( hydrogenated nitrile butadiene rubber ), ACM / AEM ( acrylate elastomers / ethylene acrylic elastomers) and polyurethanes are used to seal plain bearings such as the stern tube, gears such as Azipods, and linear guides, e.g., in rudder stabilizers. Damage to seals, which ultimately results in leaks, is primarily caused by incompatibility between the lubricant and the sealing material. Therefore, the selection of the base oil component(s) for the lubricant and the carefully coordinated selection of additives are essential to ensure not only good biocompatibility but also the material compatibility of the lubricant and thus prevent damage to sealing materials.

[0006] WO 2012 / 173878 A1 describes ester-based lubricant compositions containing water-soluble polyalkylene glycols based on ethylene oxide and propylene oxide. WO 2015 / 139209 A1 describes a lubricant containing an alcohol-initiated propylene oxide homopolymer and an oil-soluble polyalkylene glycol that does not require an ester-based base oil.

[0007] EP 2 837 674 A1 describes a lubricating oil composition which may contain a base oil mixture of synthetic polyglycol-based oils and a synthetic ester-based oil and further contains an asymmetric amine-based antioxidant.

[0008] EP 1707 617 A1 discloses ester-based lubricant compositions which have excellent biodegradability, prevent corrosion and are suitable for use with sealing materials.

[0009] However, there is still a need for environmentally friendly lubricants that reduce the chemical pollution of the oceans, inland waters and soils and that have a high compatibility with sealing materials, especially elastomer materials, and that also meet the usual requirements for the lubrication of, for example, plain bearings, gears, linear guides, pneumatic components, fittings, rolling bearings, chains, ropes, springs and screws, etc.

[0010] The object of the present invention was therefore to provide lubricants or lubricant compositions which have improved compatibility with sealing materials, in particular elastomers, which have good lubricating properties and good lubricity, which are biocompatible, i.e. readily biodegradable and minimally aquatoxic, and which are suitable for use as gear, rolling bearing, hydraulic and plain bearing oil in the marine sector and in the area of ​​inland waters, as well as in machines and machine elements on land which can come into contact with water and / or aqueous media.

[0011] For the purposes of the invention, the terms lubricant composition, lubricant, lubricating oil and formulation are used synonymously.

[0012] One or more of the above-mentioned objects can be achieved by a lubricant composition containing an oil-soluble polyalkylene glycol, an ester compound selected from the group of natural esters and synthetic esters, and combinations thereof, and an additive mixture comprising an antioxidant and a corrosion inhibitor, wherein the corrosion inhibitor is selected from neutral alkali and alkaline earth salts of sulfonic acids, carboxylic acids, naphthoic acids, naphthenic acids, benzoic acids and phosphoric acids, and their derivatives and combinations thereof.

[0013] Surprisingly, it has been found that in the lubricant composition according to the invention, which contains, as defined below, an oil-soluble polyalkylene glycol, an ester compound, and an additive mixture, wherein the additive mixture comprises an antioxidant and a neutral corrosion inhibitor, the components interact synergistically. The lubricant composition according to the invention therefore surprisingly exhibits the advantage of improved compatibility with sealing materials, in particular elastomer materials such as FKM, NBR, HNBR, ACM / AEM, or polyurethanes.In addition, the lubricant composition according to the invention has good lubricating properties and is also generally characterized by good biodegradability and / or aquatic toxicity, so that it is excellently suited for use as gear, rolling bearing, hydraulic or plain bearing oil in the marine sector and in inland waters, as well as in machines and machine elements on land that may come into contact with water and / or aqueous media.

[0014] The composition according to the invention is defined in the claims. It contains in oil-soluble polyalkylene glycol in an amount of 10-70 wt.%, based on the total lubricant composition; an ester compound selected from the group of natural esters and synthetic esters, as well as combinations thereof, in an amount of 15-85 wt.%, based on the total lubricant composition; and an additive mixture comprising an antioxidant and a corrosion inhibitor, wherein the corrosion inhibitor is selected from neutral alkali and alkaline earth salts of sulfonic acids, carboxylic acids, naphthoic acids, naphthenic acids, benzoic acids and phosphoric acids, as well as combinations thereof, wherein the neutral alkali and alkaline earth salts are Na, Ca, K and Mg salts, wherein the oil-soluble polyalkylene glycol is a copolymer selected from polybutylene oxide-polypropylene oxide copolymers, polybutylene oxide-polyethylene oxide copolymers and polybutylene oxide-polypropylene oxide-polyethylene oxide copolymers, and combinations thereof, and wherein the oil-soluble polyalkylene glycol has a molecular weight Mn of 500 g / mol or more to 1400 g / mol or less.

[0015] According to the invention, the lubricant composition contains an oil-soluble polyalkylene glycol ( oil soluble polyalkylene glycol, OSP), whereby mixtures of two or more different oil-soluble polyalkylene glycols are also included within the scope of the invention.

[0016] In the context of the invention, a polyalkylene glycol is "oil-soluble" if, after mixing it with polyalphaolefin 6 (e.g. commercially available as Synfluid ®< PAO 6 cSt or Durasyn ®< 166 polyalphaolefins) in the weight ratios 10:90, 50:50 and 90:10, respectively, and then allowing the mixtures to stand for 24 hours at room temperature, no phase separation occurs in at least two of the three mixtures.

[0017] The oil-soluble polyalkylene glycol is a copolymer selected from polybutylene oxide-polypropylene oxide copolymers, polybutylene oxide-polyethylene oxide copolymers, and polybutylene oxide-polypropylene oxide-polyethylene oxide copolymers, as well as combinations thereof, with polybutylene oxide-polypropylene oxide copolymers being particularly preferred. Furthermore, it is preferred if the copolymer is alcohol-initiated, i.e., if an alcohol was used as the initiator of the polymerization reaction during its preparation, as described in more detail below.

[0018] More preferably, the oil-soluble polyalkylene glycol is a copolymer selected from polyisobutylene oxide-polyisopropylene oxide copolymers, polyisobutylene oxide-polyethylene oxide copolymers and polyisobutylene oxide-polyisopropylene oxide-polyethylene oxide copolymers, and combinations thereof, with polyisobutylene oxide-polyisopropylene oxide copolymers being very particularly preferred.

[0019] It is particularly preferred if, in the above-mentioned copolymers, the proportion of the monomer units derived from butylene oxide or isobutylene oxide (polymerized) (ie, polybutylene oxide (BO) or polyisobutylene oxide (iBO) units) is 40 percent by weight (wt.%) or more, more preferably 50% by weight or more, for example 60% by weight or more, or 65% by weight or more, and preferably 80% by weight or less, more preferably 70% by weight or less, based on the total weight of all monomer units in the copolymer. Very particularly preferred is a polyalkylene glycol copolymer having 50 wt.% of monomer units derived from (polymerized) butylene oxide or isobutylene oxide (ie, BO or iBO units) and 50 wt.% of monomer units derived from (polymerized) propylene oxide (ie, polypropylene oxide (PO) or polyisopropylene oxide (iPO) units), based on the total weight of BO (or iBO) and PO (or iPO) units in the copolymer.This means that BO (or iBO) and PO (or iPO) units are most preferably copolymerized in a weight ratio of 50:50.

[0020] According to the invention, the oil-soluble polyalkylene glycol copolymer may be a random copolymer, a gradient copolymer, an alternating copolymer, a graft copolymer or a block copolymer, with random copolymers and block copolymers being preferred, and in particular random copolymers.

[0021] Furthermore, it is preferred if the oil-soluble polyalkylene glycol is an alcohol-initiated polyalkylene glycol. This means that the oil-soluble polyalkylene glycol used according to the invention is preferably a polyalkylene glycol prepared using an alcohol as the initiator of the polymerization reaction, wherein the alcohol preferably comprises 10-20 carbon atoms, particularly preferably 12-20 carbon atoms, so that the polyalkylene glycol has a C10-C20 alkyl radical (preferred) or C12-C20 alkyl radical (particularly preferred) bonded to at least one terminal end thereof, which results from the initial reaction of the alcohol with an alkylene oxide. Furthermore, the alcohol initiator is preferably a linear alcohol, and in particular a primary linear alcohol. Furthermore, the alcohol initiator can be a mono-, di-, or trialcohol, with a monoalcohol being preferred.

[0022] If the alcohol used as a polymerization initiator contains 10-20 carbon atoms, or if the alcohol-initiated polyalkylene glycol has a C10-C20 alkyl group bonded to at least one terminal end, the compounds added as additives, particularly antioxidants and corrosion inhibitors (see below), can be better dissolved therein. A particularly preferred alcohol initiator in this regard is n-dodecanol.

[0023] According to the invention, it is therefore particularly preferred if the oil-soluble polyalkylene glycol is a dodecanol-initiated polyalkylene glycol copolymer, with dodecanol-initiated polybutylene oxide-polypropylene oxide copolymers being particularly preferred, and polyisobutylene oxide-polyisopropylene oxide copolymers being very particularly preferred.

[0024] The oil-soluble polyalkylene glycol has a number-average molecular weight (M n ) of 500 g / mol (grams per mole) or more, more preferably 750 g / mol or more, for example 1000 g / mol or more, or 1250 g / mol or more. The molecular weight of the oil-soluble polyalkylene glycol is 1400 g / mol or less, and more preferably M n is less than 1400 g / mol.

[0025] Unless explicitly stated otherwise, "molecular weight" in the context of this invention refers to the "number average molecular weight (M n )".

[0026] The molecular weight is determined using GPC (gel permeation chromatography) against a polystyrene standard.

[0027] Oil-soluble polyalkylene glycols with a molecular weight Mn of 500 g / mol or more to 1400 g / mol or less are advantageous in terms of their biodegradability. Furthermore, the use of such oil-soluble polyalkylene glycol copolymers has been found to have a beneficial effect on the compatibility of the lubricant composition with elastomer materials.

[0028] In a further preferred embodiment of the invention, the oil-soluble polyalkylene glycol is biodegradable according to OECD 301 A - F or OECD 306 in order to achieve improved biodegradability and eco-compatibility of the lubricant composition according to the invention.

[0029] Furthermore, the oil-soluble polyalkylene glycol preferably has a kinematic viscosity at 40°C of 15 mm 2 / s or higher, more preferably 18 mm 2 / s or higher, particularly preferably 32 mm 2 / s or higher, for example 68 mm 2 / s cSt or higher, and of 130 mm 2 / s or less, more preferably 100 mm 2 / s or less. The viscosity is determined according to ASTM D 7042.

[0030] Oil-soluble polyalkylene glycols suitable for use in the invention are commercially available, for example under the brand names UCON™< OSP-18, UCON™< OSP-32, UCON™< OSP-68 and UCON™< OSP-680.

[0031] The amount of oil-soluble polyalkylene glycol in the lubricant composition is generally determined based on the amounts of the other constituents / components contained in the composition, i.e., the lubricant composition is made up to 100 wt.% with the oil-soluble polyalkylene glycol. The amount of oil-soluble polyalkylene glycol is 10-70 wt.%, based on the total weight of the lubricant composition.

[0032] The lubricant composition according to the invention also contains, as a further base oil component, an ester compound which is selected from the group of natural esters and synthetic esters, as well as combinations thereof, wherein mixtures of two or more different natural esters or mixtures of two or more different synthetic esters are also included according to the invention.In a preferred embodiment of the present invention, the ester compound is selected from natural glyceride esters, in particular from the group consisting of sunflower oil, rapeseed oil or rapeseed oil, linseed oil, corn oil, thistle oil, soybean oil, linseed oil, peanut oil, "Lesqueralle" oil, palm oil, olive oil, which may each be present in their monomeric, oligomeric and / or polymerized form; and synthetic esters from the group consisting of polyol esters, polyol complex esters, complex esters of dimer acids, dimer acid esters, aliphatic carboxylic acid and dicarboxylic acid esters, phosphate esters and trimellitic and pyromellitic acid esters; and combinations thereof.

[0033] The ester compound is particularly preferably selected from polyol esters, in particular those obtained by reacting polyhydric alcohols (i.e., polyols or alcohols having more than one hydroxyl group) with monocarboxylic acids (i.e., monobasic carboxylic acids), and polyol complex esters, in particular those obtained by reacting polyhydric alcohols with monocarboxylic acids and dicarboxylic acids (i.e., dibasic carboxylic acids) in any desired mixture, as well as combinations thereof.

[0034] The polyol esters used according to the invention are particularly preferably prepared by reaction / esterification of one or more polyhydric alcohols selected from neopentyl glycol (NPG), trimethylolpropane (TMP) and pentaerythritol (PE), or dimers or trimers thereof, with one or more linear and / or branched monocarboxylic acids of chain length C4-C36 (i.e., 4 to 36 carbon atoms), preferably C10-36, particularly preferably C14-C36, and very particularly preferably C18-C36, which may be saturated and / or mono- or polyunsaturated, and are preferably saturated.

[0035] Likewise particularly preferably, the polyol complex esters used according to the invention are prepared by reaction / esterification of one or more polyhydric alcohols selected from neopentyl glycol (NPG), trimethylolpropane (TMP) and pentaerythritol (PE), or dimers or trimers thereof, in any desired mixture with one or more linear and / or branched monocarboxylic acids of chain length C4-C36, preferably C10-C36, particularly preferably C14-C36, and very particularly preferably C18-C36, which may be saturated and / or mono- or polyunsaturated, and are preferably saturated, and one or more linear and / or branched dicarboxylic acids of chain length C4-C36, preferably C4-C18, particularly preferably C4-C12, which may be saturated and / or mono- or polyunsaturated, and are preferably saturated.

[0036] The polyol complex esters obtained in this way can be fully esterified or partially esterified (i.e., free, non-esterified hydroxyl groups are still present).

[0037] In a particularly preferred embodiment of the invention, the ester compound is therefore selected from neopentyl glycol esters, trimethylolpropane esters, and pentaerythritol esters, which are esterified in particular with saturated and / or mono- or polyunsaturated, linear and / or branched monocarboxylic acids of chain length C4-C36, preferably C10-C36, particularly preferably C14-C36, and very particularly preferably C18-C36;and neopentyl glycol complex esters, trimethylolpropane complex esters, and pentaerythritol complex esters, which are fully esterified or partially esterified in particular with saturated and / or mono- or polyunsaturated, linear and / or branched monocarboxylic acids of chain length C4-C36, preferably C10-C36, particularly preferably C14-C36, and very particularly preferably C18-C36, and with saturated and / or mono- or polyunsaturated, linear and / or branched dicarboxylic acids of chain length C4-C36, preferably C4-C18, particularly preferably C4-C12, in any desired mixture; and combinations thereof.

[0038] Examples of particularly preferred ester compounds are, without limitation, pentaerythritol tetraisostearate, pentaerythritol tetraoleate, pentaerythritol isostearate sebacate complex ester, trimethylolpropane triisostearate, trimethylolpropane trioleate, trimethylolpropane tricaprylate, trimethylolpropane isostearate stearate sebacate complex ester, neopentyl glycol diisostearate.

[0039] Suitable ester compounds are also commercially available, for example under the brand names Priolube 3987, Radialube 7257, Synative ES 1200, Priolube 1973, Synative ES TMP 05 / 140, Palub 8433, Nycobase 8397, Estilube P 688, Rümanox 804.

[0040] It has been shown that the presence / addition of such ester compounds, especially those containing the residue of a monocarboxylic acid with a chain length of C18-C36, has a beneficial effect on compatibility with elastomer materials. The ester compounds defined above are also generally characterized by good biodegradability.

[0041] In a further preferred embodiment of the invention, ester compounds are used which are biodegradable according to OECD 301 A - F or OECD 306 in order to achieve improved biodegradability and ecological compatibility of the lubricant composition according to the invention.

[0042] The ester compound is contained in the lubricant composition according to the invention in an amount of 15 - 85 wt.%, based on the total lubricant composition.

[0043] According to a particularly preferred embodiment of the invention, the oil-soluble polyalkylene glycol and the ester compound are the only base oil components in the lubricant composition. This means that the lubricant composition according to the invention contains, as base oil components, only oil-soluble polyalkylene glycol—a single compound or a mixture of various OSPs—and an ester compound—a single compound or a mixture of various ester compounds—but no other base oil components, in particular no mineral oil. The weight ratio of "oil-soluble polyalkylene glycol" to "ester compound" based on the total weight of these two components in the lubricant composition is preferably in the range from 5:95 to 95:5, more preferably from 10:90 to 80:20, and particularly preferably from 15:85 to 70:30.

[0044] The lubricant composition according to the invention further contains an additive mixture comprising an antioxidant and a corrosion inhibitor. The antioxidant and the corrosion inhibitor can each be present in the lubricant composition as a single substance or as a mixture of different antioxidants or corrosion inhibitors. The same applies to any other additive optionally present in the lubricant composition.

[0045] Through the targeted addition of additives, certain properties of the lubricant can be improved and / or certain properties can be given to the lubricant.

[0046] The addition of corrosion inhibitors gives the lubricant composition a corrosion and rust-inhibiting effect.

[0047] According to the invention, the corrosion inhibitor is selected from neutral alkali and alkaline earth salts of sulfonic acids, carboxylic acids, naphthenic acids, naphthoic acids, benzoic acids, and phosphoric acids, as well as combinations thereof. Within the scope of the present invention, this also includes derivatives of the aforementioned acids / acid salts, including linear and branched aliphatic and aromatic derivatives of these acids / acid salts, which may additionally be substituted by one or more radicals selected from linear and / or branched alkyl radicals and aryl radicals. The alkali and alkaline earth salts of these acids are the Na, Ca, K, and Mg salts, and Ca salts are preferred, particularly for reasons of environmental compatibility.

[0048] For the purposes of the present invention, "neutral" acid salts are understood to mean acid salts which have an acid number (TAN) of 30 mg KOH / g or less.

[0049] It is therefore preferred within the scope of the present invention that the corrosion inhibitor, or the neutral sulfonic acid, carboxylic acid, naphthenic acid, naphthoic acid, benzoic acid or phosphoric acid salt used, or mixtures thereof, has a TAN of 30 mg KOH / g or less, more preferably 20 mg KOH / g or less, particularly preferably 15 mg KOH / g or less, and most preferably 10 mg KOH / g or less.

[0050] In a particularly preferred embodiment, the corrosion inhibitor is selected from neutral calcium sulfonates. These have proven particularly advantageous with regard to the compatibility of the lubricant composition with elastomer materials. An example of a particularly suitable corrosion inhibitor according to the invention is neutral alkylnaphthalenesulfonic acid calcium salts, but these are not limited to these.

[0051] Suitable neutral corrosion inhibitors are commercially available, e.g. under the brand names NA-SUL ®< CA-770 FG or NA SUL ®< CA 1089.

[0052] It has surprisingly been found that, by the targeted addition of the neutral acid salts as defined above to the lubricant composition, in addition to the corrosion and rust-inhibiting effect, an improvement in the compatibility of the lubricant composition with sealing materials, in particular elastomer materials, is achieved, which results in particular from a synergistic interaction with the other components of the lubricant composition.

[0053] The oxidation stability of the lubricant composition can be increased by adding antioxidants.

[0054] In a preferred embodiment of the present invention, the antioxidant is selected from phenolic antioxidants (phenol compounds), aminic antioxidants (amine compounds), phosphites and sulfur-containing compounds, in particular alkyl and aryl sulfides, sulfur-containing phenol compounds and sulfur-containing carboxylic acids, phosphothionates, thiocarbamates and dithiocarbamates, thiophosphates and thiopropionates, and combinations thereof, with phenolic antioxidants, aminic antioxidants, thiocarbamates and dithiocarbamates being particularly preferred.Most preferably, the antioxidant is selected from aminic antioxidants, and in particular from linear or branched aliphatic amine compounds and aromatic amine compounds and their salts, where the aliphatic and aromatic amine compounds may be substituted by one or more radicals selected from linear and / or branched alkyl radicals and aryl radicals.

[0055] Preferred antioxidants are selected from aromatic diamines and secondary aromatic amines, phenolic resins, thiophenol resins, zinc thiocarbamate, zinc thiophosphate, organic thiocarbamates and dithiocarbamates, butylated hydroxytoluene, butylated hydroxyanisole, phenyl-alpha-naphthylamines, phenyl-betanaphthylamines, diphenylamine and diphenylamine derivatives, in particular octylated diphenylamines, butylated diphenylamines and styrenated diphenylamines, quinoline and quinoline derivatives, naphtylamine and naphtylamine derivatives, di-alpha-tocopherol, ditert-butylphenylpropanoic acid and its esters, and mixtures thereof, without being limited thereto.

[0056] Examples of particularly preferred antioxidants according to the invention are benzenamine, N-phenyl, reaction products with 2,4,4-trimethylpentene, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, bis(4-(1,1,3,3-tetramethylbutyl)phenyl)amine, N-[(1,1,3,3-tetramethylbutyl)phenyl]naphthalene-1-amine 4,4'-methylenebis(dibutyldithiocarbamate), without being limited thereto.

[0057] Suitable antioxidants are commercially available, e.g. under the brand names Vanlube ®< 81, Irganox ®< L 57, Vanlube ®< 1202 or Irganox ®< L 107 ADDITIN RC 6340.

[0058] It was surprisingly found that by the targeted selection of the antioxidant, in particular the targeted use of amine compounds, phenol compounds and / or thiocarbamates and dithiocarbamates as antioxidants, in addition to the increase in oxidation stability, an improvement in the compatibility of the lubricant composition with sealing materials, in particular elastomer materials, can be achieved, which results in particular from a synergistic interaction with the other components of the lubricant composition.

[0059] The amount of the additive mixture in the lubricant composition, i.e., the total amount of all additives in the lubricant composition, is preferably 0.1-20 wt.%, more preferably 0.1-10 wt.%, and particularly preferably 0.1-5 wt.%, based on the total lubricant composition. The amount of the antioxidant is preferably in the range of 0.05-3.5 wt.%, and the amount of the corrosion inhibitor is preferably in the range of 0.05-3.5 wt.%, each based on the total lubricant composition, whereby the above-defined total amount of all additives is not exceeded.

[0060] In a preferred embodiment, the present invention therefore relates to a lubricant composition containing in an amount of 10-70 wt.% based on the total lubricant composition, an oil-soluble polyalkylene glycol; in an amount of 15-85 wt.% based on the total lubricant composition, an ester compound selected from the group consisting of natural esters and synthetic esters, and combinations thereof; and in an amount of 0.1-20 wt.% based on the total lubricant composition, an additive mixture comprising an antioxidant and a corrosion inhibitor, wherein the corrosion inhibitor is selected from neutral alkali and alkaline earth salts of sulfonic acids, carboxylic acids, naphthenic acids, naphthoic acids, benzoic acids and phosphoric acids, and their derivatives and combinations thereof, and wherein the components contained add up to a total of 100 wt. % and are as defined above, wherein the neutral alkali and alkaline earth salts are Na, Ca, K and Mg salts, wherein the oil-soluble polyalkylene glycol is a copolymer selected from polybutylene oxide-polypropylene oxide copolymers, polybutylene oxide-polyethylene oxide copolymers and polybutylene oxide-polypropylene oxide-polyethylene oxide copolymers, and combinations thereof, and wherein the oil-soluble polyalkylene glycol has a molecular weight Mn of 500 g / mol or more to 1400 g / mol or less.

[0061] In a further preferred embodiment of the invention, the additive mixture comprises, in addition to antioxidant(s) and corrosion inhibitor(s), a non-ferrous metal deactivator, wherein both individual compounds and mixtures of two or more different non-ferrous metal deactivators are included within the scope of the invention.

[0062] By adding non-ferrous metal deactivators, non-ferrous metals such as cadmium (Cd), cobalt (Co), copper (Cu), nickel (Ni), lead (Pb), tin (Sn), and zinc (Zn), which are considered non-ferrous metals, as well as their alloys, can be protected from corrosion by active sulfur.

[0063] The non-ferrous metal deactivator is preferably selected from triazoles, mercaptothiadiazoles, and salicylates, as well as combinations thereof, with triazoles and especially benzotriazoles being particularly preferred. Within the scope of the present invention, the terms "triazoles" and "benzotriazoles" also encompass triazole derivatives and benzotriazole derivatives, respectively, as well as reaction mixtures and reaction masses in which these are present as individual compounds or in multiples.

[0064] Examples of non-ferrous metal deactivators that are particularly suitable according to the invention are benzotriazole and tolyltriazole and derivatives thereof, N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine, and a reaction mass of N,N-bis(2-ethylhexyl)-6-methyl-1H-benzotriazole-1-methanamine, N,N-bis(2-ethylhexyl)-4-methyl-2H-benzotriazole-2-methanamine, N,N-bis(2-ethylhexyl)-5-methyl-2H-benzotriazole-2-methanamine, N,N-bis(2-ethylhexyl)-4-methyl-1H-benzotriazole-1-methylamine and N,N-bis(2-ethylhexyl)-5-methyl-1H-benzotriazole-1-methylamine, without being limited thereto.

[0065] Suitable non-ferrous metal deactivators are commercially available, e.g. under the brand names Irgamet ®< 39 or Irgamet ®< BTZ.

[0066] Through the targeted selection of the non-ferrous metal deactivator, in particular the targeted use of triazoles or benzotriazoles, in addition to the protection against corrosion by active sulfur, a further improvement in the compatibility of the lubricant composition with sealing materials, in particular elastomer materials, can be achieved, which results in particular from a synergistic interaction with the other components of the lubricant composition.

[0067] In a further preferred embodiment, the present invention therefore relates to a lubricant composition containing in an amount of 10-70 wt.% based on the total lubricant composition, an oil-soluble polyalkylene glycol; in an amount of 15-85 wt.% based on the total lubricant composition, an ester compound selected from the group consisting of natural esters and synthetic esters, and combinations thereof; and in an amount of 0.1-20 wt.% based on the total lubricant composition, an additive mixture comprising an antioxidant, a corrosion inhibitor, and a non-ferrous metal deactivator, wherein the corrosion inhibitor is selected from neutral alkali and alkaline earth salts of sulfonic acids, carboxylic acids, naphthenic acids, naphthoic acids, benzoic acids and phosphoric acids, and combinations thereof, and wherein the components present add up to a total of 100% by weight and are as defined above, wherein the neutral alkali and alkaline earth salts are Na, Ca, K and Mg salts, wherein the oil-soluble polyalkylene glycol is a copolymer selected from polybutylene oxide-polypropylene oxide copolymers, polybutylene oxide-polyethylene oxide copolymers and polybutylene oxide-polypropylene oxide-polyethylene oxide copolymers, and combinations thereof, and wherein the oil-soluble polyalkylene glycol has a molecular weight Mn of 500 g / mol or more to 1400 g / mol or less.

[0068] The lubricant composition according to the invention, or the additive mixture used, may comprise, in addition to antioxidant(s), corrosion inhibitor(s) and optionally non-ferrous metal deactivator(s), one or more further additives, which are in particular selected from wear inhibitors, friction reducers, high-pressure additives, ion complexing agents, solid lubricants, dispersants, pour point and viscosity improvers, UV stabilizers, emulsifiers, color indicators, slip improvers and defoamers, without being limited thereto.

[0069] Wear protection agents, friction reducers and high-pressure additives suitable according to the invention are preferably selected from amines, amine phosphates, branched and / or linear alkylated phosphates, phosphites, thiophosphates, and phosphothioates, aryl phosphates, aryl thiophosphates, alkylated polysulfides, sulfurized amine compounds, sulfurized fatty acid methyl esters, naphthenic acids, nanoparticles selected from Al 2 O 3 , SiO 2 , TiO 2 , ZrO 2 , WO 3 , Ta 2 O 5 , V 2 O 5 , CeO 2 , aluminum titanate, BN, MoSi 2 , SiC, Si 3 N 4 , TiC, TiN, ZrB 2 , clay minerals and mixtures thereof, sulfonic acid salts, and thermally stable carbonates and sulfates, as well as mixtures of two or more including, but not limited to,Suitable commercially available additives are, for example, the following products: IRGALUBE ®< TPPT, IRGALUBE ®< 232, IRGALUBE ®< 349, IRGALUBE ®< 353, IRGALUBE ®< 211 and ADDITIN ®< RC3760 Liq 3960, FIRC-SHUN ®< FG 1505 and FG 1506, NA-LUBE ®< KR-015FG, LUBEBOND ®< , FLUORO ®< FG, SYNALOX ®< 40-D, ACHESON ®< FGA 1820 and ACHESON ®< FGA 1810.

[0070] Suitable viscosity improvers are preferably selected from linear and branched alkylated, acrylated, and aliphatic polymers and copolymers, as well as polymerized fatty acid esters, and mixtures of two or more thereof. Examples of suitable viscosity improvers include, but are not limited to, polymethacrylate, ethylene-propylene copolymer, polyisobutylene, polyalkylstyrene, and hydrogenated styrene-isoprene copolymer. Suitable viscosity improvers are commercially available.

[0071] Suitable UV stabilizers are preferably selected from, but are not limited to, nitrogen heterocycles and substituted nitrogen heterocycles, as well as mixtures of two or more thereof. Suitable UV stabilizers are commercially available.

[0072] Suitable solid lubricants are preferably selected from, but are not limited to, PTFE, boron nitride, zinc oxide, magnesium oxide, pyrophosphates, thiosulfates, magnesium carbonate, calcium carbonate, calcium stearate, zinc sulfide, molybdenum sulfide, tungsten sulfide, tin sulfide, graphite, graphene, nanotubes, SiO2 modifications, and mixtures of two or more thereof. Suitable solid lubricants are commercially available.

[0073] Suitable emulsifiers are preferably selected from branched and / or linear ethoxylated and / or propoxylated alcohols and their salts, in particular alcohols with chain lengths of 14-18 carbon atoms, ethoxylated and / or propoxylated alkyl ethers, fatty acid esters, and ionic surfactants such as sodium salts of alkylsulfonic acids, as well as mixtures of two or more thereof, without being limited thereto. Suitable emulsifiers are commercially available.

[0074] The addition of defoamers prevents foam formation. Suitable defoamers are preferably selected from ethoxylated and / or propoxylated alcohols with chain lengths of 10-18 carbon atoms, mono- and diglycerides of edible fats, acrylates, propoxylated and / or ethoxylated alkyl ethers, polyols including diols, and polysiloxanes such as silicone oils or polydimethylsiloxanes, as well as mixtures of two or more thereof, but not limited to these. Suitable defoamers are commercially available.

[0075] An example of a suitable color indicator is, but is not limited to, 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole). Suitable color indicators are commercially available.

[0076] A slip enhancer, within the meaning of the present invention, is an organic compound that comprises both a polar and a non-polar moiety. The term "organic compound" encompasses both individual compounds (i.e., molecules) and mixtures of individual compounds, as well as oligomers and polymers, including homopolymers, copolymers, and polymer blends, as well as mixtures thereof.

[0077] By adding the sliding improver to the lubricant composition, an improvement in the sliding properties of the lubricant composition can be achieved, especially at low gear and bearing speeds and high loads.

[0078] Preferred examples of organic compounds which can advantageously be used as slip improvers in the lubricant composition according to the invention are the following compounds, without being limited thereto: maleic acid-olefin copolymers (commercially available, for example, as Ketjenlube®< 135, Ketjenlube®< 2700, Ketjenlube®< 23000); modified polyesters (commercially available, for example, as Perfad™< 3000, Perfad™< 3050); polymethyl methacrylate (PMMA), linear polymers and star polymers (commercially available, for example, as Lubrizol 87725); oleic acid, in particular mixtures of C16-C18 fatty acids and C18 unsaturated fatty acids (commercially available, for example, as Herwemag OA); Glycerol monooleates (GMO), especially those with a mono content of at least 40%, free glycerol of max. 6% (commercially available, e.g., as Ilco Lube 2316); polymethacrylate (PMA), linear polymers and comb polymers (commercially available, e.g.,as Viscoplex ®< 3-200); comb polymers of 1-decene and 9-dodecylic acid methyl ester (commercially available, e.g., as Elevance Aria ®< WTP 40); pentaerythritol tetraisostearate (commercially available, e.g., as Priolube ™< 3987-LQ).

[0079] Since the additives serve to improve certain properties of the lubricant and / or to impart certain properties to it, they can be added to the lubricant as a single substance or as a mixture of two or more additives, depending on the need or requirement of the lubricant, whereby the amount of additives in the additive mixture is not limited, as long as the total amount of all additives defined above, based on the entire lubricant composition, is not exceeded or fallen below.

[0080] In a further preferred embodiment of the invention, the acid number of the entire lubricant composition is 30 mg KOH / g or less, more preferably 20 mg KOH / g or less, particularly preferably 15 mg KOH / g or less, and most preferably 10 mg KOH / g or less.

[0081] In a further preferred embodiment, the lubricant composition has a kinematic viscosity at 40°C of 20 mm 2 / s to 680 mm 2 / s, more preferably of 30 mm 2 / s to 480 mm 2 / s, and most preferably of 60 mm 2 / s to 150 mm 2 / s. Viscosity measurements are carried out according to ASTM D 7042.

[0082] In a further preferred embodiment, the lubricant composition is biodegradable according to OECD 301 A - F or OECD 306 and / or has low aquatic toxicity according to OECD 201, 202, 203 or 236.

[0083] It has surprisingly been found that the lubricant composition according to the invention described herein, which contains, as defined above, an oil-soluble polyalkylene glycol, an ester compound, and an additive mixture comprising an antioxidant and a neutral corrosion inhibitor, exhibits the advantage of improved compatibility with sealing materials, particularly elastomers, resulting in particular from a synergistic interaction of the components. The lubricant composition according to the invention also exhibits good lubricating and sliding properties and good biodegradability and ecological compatibility.

[0084] The lubricant composition according to the invention is therefore ideally suited for use as a gear, rolling bearing, hydraulic or plain bearing oil in the marine sector and in inland waters, as well as in machines and machine elements on land that may come into contact with water and / or aqueous media.

[0085] A further object of the present invention therefore relates to the use of the lubricant composition according to the invention described herein as gear, rolling bearing, hydraulic and plain bearing oil in the marine sector and in the area of ​​inland waters, as well as in machines and machine elements on land which can come into contact with water and / or aqueous media.

[0086] Areas of application in the marine sector and in inland waters include, in particular, the lubrication of gears, hydraulics, bearings such as plain, roller or stern tube bearings, propeller rudders, propeller shafts, pneumatic components, linear guides, chains and ropes in machines, machine components and systems that come into contact with salt water in the marine sector, for example offshore installations, or with (fresh) water and / or aqueous media in inland waters, but are not limited to this.

[0087] In the marine sector, gearboxes are used in thrusters and azipods, for example. These applications serve to transmit and convert power between the drive and the propeller. In these cases, both water ingress and lubricant leakage into the marine environment are to be expected.

[0088] Another application in the marine sector is jack-up systems that lift platforms, installation vessels for wind turbines, or drilling rigs. This movement is achieved through open gears.

[0089] Hydraulic systems in the marine sector are used to drive adjustable propeller rudders, as well as fin stabilizers and rudder bearings. Linear guides are also used in the latter, which are usually lubricated with the same lubricant. Here, too, lubrication takes place below the waterline. Accordingly, water ingress into the machine components and lubricant leakage into the marine environment are to be expected.

[0090] The primary application of plain bearings in the marine sector is a propeller shaft bearing located in the stern tube, the so-called stern tube bearing. The primary function of the propeller shaft is to transmit the drive motion through the ship's hull to the propeller. The bearing ensures low-friction movement.

[0091] Furthermore, machines and machine components in offshore wind turbines, oil and gas production platforms, port facilities, shipyards and the like that come into contact with seawater, water and aqueous media are lubricated.

[0092] This includes chains used in lock gates, for example; ropes such as ship's rope or ropes used in nets; and valves for regulating solid, liquid, and gas flows. Screws, springs, and valves in a wide variety of equipment and machines also require lubrication.

[0093] In a preferred embodiment, the present invention therefore relates to the use of the lubricant composition according to the invention described herein as gear oil, rolling bearing oil, hydraulic oil or plain bearing oil in the marine sector and in the area of ​​inland waters, in particular for the lubrication of gears, hydraulics, propeller rudders, propeller shafts, linear guides, pneumatic components, fittings, bearings, such as plain, rolling or stern tube bearings, chains, ropes, springs, valves and screws in machines, machine components and systems that come into contact with water (salt and / or fresh water), as well as in machines and machine elements on land that come into contact with water and / or aqueous media, wherein the lubricant composition preferably contains: in an amount of 10-70 wt.% based on the total lubricant composition, an oil-soluble polyalkylene glycol; in an amount of 15-85 wt.% based on the total lubricant composition, an ester compound selected from the group of natural esters and synthetic esters, and combinations thereof; and in an amount of 0.1-20 wt.% based on the total lubricant composition, an additive mixture comprising an antioxidant, a corrosion inhibitor, and optionally a non-ferrous metal deactivator, wherein the corrosion inhibitor is selected from neutral alkali and alkaline earth salts of sulfonic acids, carboxylic acids, naphthenic acids, naphthoic acids, benzoic acids and phosphoric acids, as well as derivatives and combinations thereof, and wherein the components contained add up to a total of 100 wt. % and are as defined above, wherein the neutral alkali and alkaline earth salts are Na, Ca, K and Mg salts, wherein the oil-soluble polyalkylene glycol is a copolymer selected from polybutylene oxide-polypropylene oxide copolymers, polybutylene oxide-polyethylene oxide copolymers and polybutylene oxide-polypropylene oxide-polyethylene oxide copolymers, as well as combinations thereof, and wherein the oil-soluble polyalkylene glycol has a molecular weight Mn of 500 g / mol or more to 1400 g / mol or less.

[0094] The lubricant compositions are produced according to a procedure known to those skilled in the art, in which the base oil components (oil-soluble polyalkylene glycol(s), ester compound(s)) and the additives are mixed in a suitable vessel, e.g., a mixing vessel, using a suitable stirrer. Solid additives or components are dissolved by increasing the temperature and stirred in. Production can also be carried out using continuous processes.

[0095] The present invention is described in more detail by the following non-limiting examples. Examples General test methods used:

[0096] The properties of the lubricant composition and the components it contains are determined using the following methods, unless known by the manufacturer: Determination of viscosity: Viscosity measurements are performed according to ASTM D 7042 using a Stabinger SVM 3000 viscometer (Anton Paar). Determination of acid number (TAN, total acid number [mg KOH / g]):

[0097] To determine the acid number, the sample is dissolved in a solvent mixture and then titrated with an alcoholic potassium hydroxide solution according to ASTM D664-18E02. The titration is performed potentiometrically using a Solvotrode on a Metrohm 905 Titrando titration unit. Determination of molecular weight (M n ):

[0098] The molecular weight is determined by GPC (gel permeation chromatography) against a polystyrene standard according to DIN 55672-1:2016-03 "Gel permeation chromatography (GPC) - Part 1: Tetrahydrofuran (THF) as eluent" using a SECcure GPC system. Production of lubricant compositions:

[0099] The lubricant compositions are produced according to a procedure known to those skilled in the art, in which the base oil components (oil-soluble polyalkylene glycol(s), ester compound(s)) and the additives are mixed in a suitable vessel, e.g., a mixing vessel, using a suitable stirrer. Solid additives or components are dissolved by increasing the temperature and stirred in. Production can also be carried out using continuous processes.

[0100] The following formulations according to the invention (Examples 1-5) and not according to the invention (Comparative Examples 1-11) are prepared as described above: Example 1

[0101] Chemistry 1 Chemistry 2 Proportion (wt.%) Base oil 1 Oil-soluble polyalkylene glycol Polyisobutylene oxide (iBO)-polyisopropylene oxide (iPO) copolymer; iBO:iPO 50:50, dodecanolin initiated 19,0 Base oil 2 Pentaerythritol ester Pentaerythritol tetraisostearate 76,305 Additive mixture Corrosion inhibitors Neutral calcium sulfonate 1< (TAN < 10 mg KOH / g) 4,695 Antioxidants Phenolic Antioxidant 2< Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Example 2

[0102] Chemistry 1 Chemistry 2 Proportion (wt%) Base oil 1 Oil-soluble polyalkylene glycol iBO-iPO copolymer; iBO:iPO 50:50, dodecanolin initiated 19,5 Base oil 2 Pentaerythritol ester Pentaerythritol tetraisostearate 76,305 Additive mixture Corrosion inhibitors Neutral calcium sulfonate 1< (TAN < 10 mg KOH / g) 4,195 Antioxidants Aminic Antioxidant 3< Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Example 3

[0103] Chemistry 1 Chemistry 2 Proportion (wt%) Base oil 1 Oil-soluble polyalkylene glycol iBO-iPO copolymer; iBO:iPO 50:50, dodecanolin initiated 19,9 Base oil 2 Pentaerythritol ester Pentaerythritol tetraisostearate 76,305 Additive mixture Corrosion inhibitors Neutral calcium sulfonate 1< (TAN < 10 mg KOH / g) 3,795 Antioxidants Aminic Antioxidant 4< Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Example 4

[0104] Chemistry 1 Chemistry 2 Proportion (wt%) Base oil 1 Oil-soluble polyalkylene glycol iBO-iPO copolymer; iBO:iPO 50:50, dodecanolin initiated 60,0 Base oil 2 Pentaerythritol complex ester Pentaerythritol isostearate sebacate complex ester 35,305 Additive mixture Corrosion inhibitors Neutral calcium sulfonate 1< (TAN < 10 mg KOH / g) 4,695 Antioxidants Phenolic Antioxidant 2< Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Example 5

[0105] Chemistry 1 Chemistry 2 Proportion (wt%) Base oil 1 Oil-soluble polyalkylene glycol iBO-iPO copolymer; iBO:iPO 50:50, dodecanolin initiated 19,0 Base oil 2 Pentaerythritol ester Pentaerythritol tetraisostearate 75,805 Additive mixture Corrosion inhibitors Neutral calcium sulfonate 1< (TAN < 10 mg KOH / g) 5,195 Antioxidants Thiocarbamate 10< Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Comparison example 1

[0106] Chemistry 1 Chemistry 2 Proportion (wt.%) Base oil 1 Oil-soluble polyalkylene glycol iBO-iPO copolymer; iBO:iPO 50:50, dodecanolin initiated 19,5 Base oil 2 Pentaerythritol ester Pentaerythritol tetraisostearate 76,805 Additive mixture Corrosion inhibitors Neutral calcium sulfonate 1< (TAN < 10 mg KOH / g) 3,695 Antioxidants -- Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Comparison example 2

[0107] Chemistry 1 Chemistry 2 Proportion (wt%) Base oil 1 Oil-soluble polyalkylene glycol iBO-iPO copolymer; iBO:iPO 50:50, dodecanolin initiated 21 Base oil 2 Pentaerythritol ester Pentaerythritol tetraisostearate 74,705 Additive mixture Corrosion inhibitors Amine-neutralized phosphate 5<; sarcosine derivative 6< (TAN > 100 mg KOH / g) 4,295 Antioxidants Phenolic Antioxidant 2< Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Comparison example 3

[0108] Chemistry 1 Chemistry 2 Proportion (wt.%) Base oil 1 Oil-soluble polyalkylene glycol iBO-iPO copolymer; iBO:iPO 50:50, dodecanolin initiated 19,0 Base oil 2 Pentaerythritol ester Pentaerythritol tetraisostearate 76,705 Additive mixture Corrosion inhibitors Carboxylic acid half ester 7< ; Sarcosine derivative 6< (TAN > 100 mg KOH / g) 4,295 Antioxidants Phenolic Antioxidant 2< Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Comparison example 4

[0109] Chemistry 1 Chemistry 2 Proportion (wt.%) Base oil 1 Oil-soluble polyalkylene glycol iBO-iPO copolymer; iBO:iPO 50:50, dodecanolin initiated 19,0 Base oil 2 Pentaerythritol ester Pentaerythritol tetraisostearate 76,71 Additive mixture Corrosion inhibitors Carboxylic acid half esters 7< ; (TAN > 100 mg KOH / g) 4,29 Antioxidants Phenolic antioxidant Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Comparison example 5

[0110] Chemistry 1 Chemistry 2 Proportion (wt.%) Base oil 1 Oil-soluble polyalkylene glycol iBO-iPO copolymer; iBO:iPO 50:50, dodecanolin initiated 19,71 Base oil 2 Pentaerythritol ester Pentaerythritol tetraisostearate 76,0 Additive mixture Corrosion inhibitors Carboxylic acid diesters 8< , carboxylic acid half esters 7< ; (TAN > 100 mg KOH / g) 4,29 Antioxidants Phenolic Antioxidant 2< Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Comparison example 6

[0111] Chemistry 1 Chemistry 2 Proportion (wt.%) Base oil 1 Oil-soluble polyalkylene glycol iBO-iPO copolymer; iBO:iPO 50:50, dodecanolin initiated 19,71 Base oil 2 Pentaerythritol ester Pentaerythritol tetraisostearate 76,0 Additive mixture Corrosion inhibitors Carboxylic acid half esters 9< (TAN > 100 mg KOH / g) 4,29 Antioxidants Phenolic Antioxidant 2< Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Comparison example 7

[0112] Chemistry 1 Chemistry 2 Proportion (wt%) Base oil 1 Pentaerythritol esters Pentaerythritol tetraisostearate 51,764 Base oil 2 Pentaerythritol esters Pentaerythritol tetraoleate 43,041 Additive mixture Corrosion inhibitors Neutral calcium sulfonate 1< (TAN < 10 mg KOH / g) 5,195 Antioxidants Thiocarbamate 10< Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Comparison example 8

[0113] Chemistry 1 Chemistry 2 Proportion (wt%) Base oil 1 Pentaerythritol esters Pentaerythritol tetraoleate 43,041 Base oil 2 Pentaerythritol esters Pentaerythritol tetraisostearate 52,264 Additive mixture Corrosion inhibitors Neutral calcium sulfonate 1< (TAN < 10 mg KOH / g) 4,695 Antioxidants Phenolic Antioxidant 2< Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Comparison example 9

[0114] Chemistry 1 Chemistry 2 Proportion (wt%) Base oil 1 Pentaerythritol esters Pentaerythritol tetraoleate 44,541 Base oil 2 Pentaerythritol esters Pentaerythritol tetraisostearate 51,664 Additive mixture Corrosion inhibitors Neutral calcium sulfonate 1< (TAN < 10 mg KOH / g) 3,795 Antioxidants Aminic Antioxidant 4< Non-ferrous metal deactivator Benzotriazole derivative Glide improver Maleic acid-olefin copolymer Defoamers Silicone-containing defoamer Comparison example 10

[0115] Chemistry 1 Chemistry 2 Proportion (wt%) Base oil 1 Polyalkylene glycol Polypropylene glycol 11< 68,48 Base oil 2 Pentaerythritol esters Pentaerythritol tetraisostearate 29,32 Additive mixture Corrosion inhibitors Basic barium sulfonate 12< 2,20 Antioxidants Aminic Antioxidant 4< Non-ferrous metal deactivator Benzotriazole (CAS No. 95-14-7) Comparison example 11

[0116] Chemistry 1 Chemistry 2 Proportion (wt%) Base oil 1 Polyalkylene glycol Polypropylene glycol 11< 68,48 Base oil 2 Trimethylolpropane ester Trimethylolpropane fatty acid esters (mainly C18-subst.) 29,32 Additive mix ch Corrosion inhibitors Basic barium sulfonate 12< 2,20 Antioxidants Aminic Antioxidant 4< Non-ferrous metal deactivator Benzotriazole (CAS No. 95-14-7) 1< neutral alkylnaphthalenesulfonic acid calcium salt (NA-SUL ®< CA-770 FG); 2< octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (CAS No. 2082-79-3); 3< benzenamine, N-phenyl, reaction products with 2,4,4-trimethylpentene, (CAS No. 68411-46-1); 4< bis(4-(1,1,3,3-tetramethylbutyl)phenyl)amine (CAS No. 15721-78-5); 5< amines, C11-14 branched alkyl, monohexyl and dihexyl phosphates (CAS No. 80939-62-4); 6< N-oleoylsarcosine; 7< 2-(Tetrapropenyl)succinic acid, monoester with propane-1,2-diol (CAS No. 52305-09-6); 8< (Tetrapropenyl)succinic acid (CAS No. 27859-58-1); 9< Reaction products of dihydro-3-(tetrapropenyl)furan-2,5-dione with propane-1,2-diol (EC No. 947-696-0); 10< 4,4'-Methylenebis(dibutyldithiocarbamate) (CAS No. 10254-57-6); 11< Polypropylene glycol monobutyl ether, n-butanol initiated (Synalox™< 100-40B DOW, Mn 1100 g / mol); 12< Barium bis(dinonylnaphthalenesulfonate) in mineral oil (CAS No. 25619-56-1; King Industries Na-Sul ®< BSN, pH 10) Example 6 - Determination of elastomer compatibility:

[0117] When selecting a suitable elastomer material, in addition to the temperature range, the chemical and physical resistance of the elastomer is often crucial. Elastomers are subject to aging and wear, which in turn determine their service life in the application.

[0118] To determine elastomer compatibility with lubricants, elastomer test specimens (NBR and FKM test specimens) are immersed in formulations from Examples 1-5 and Comparative Examples 1-7, and the effect of the respective formulation on the elastomer material is investigated. As a measure of elastomer compatibility, the change in material properties such as hardness, weight, volume, tensile strength, or elongation at break after immersion in the lubricant compared to the as-delivered condition is determined.

[0119] Storage tests are carried out in both pure lubricating oil and an oil-water emulsion using commercially available equipment.

[0120] The immersion tests in pure lubricating oil are conducted according to DIN ISO 1817 (DIN ISO 1817:2016-11). The following elastomer test specimens are exposed to pure lubricating oil under the following measurement conditions: FKM: 80 FKM 10061: 168 h / 150 °C; 85 FKM 245601: 168 h / 150 °C NBR: ISO 6072 NBR 1: 1000 hours / 100 °C

[0121] The immersion tests in oil-water emulsions are carried out in accordance with DIN ISO 1817 (DIN ISO 1817:2016-11). The test oil is placed in a suitable test vessel (e.g., a 2000 ml flat-flange beaker with a groove, DN 120, with a flat-ground lid, DN 120) and mixed with 5% distilled water (for 1600 ml oil: 85 ml water, for 1800 ml oil: 95 ml water) and stirred until homogeneous. The test specimens are completely immersed in the test oil and arranged so that the distance to the side walls of the test vessel is at least 5 mm, to the bottom of the vessel and to the surface of the test oil is at least 10 mm. After attaching a contact thermometer and a reflux condenser, the test vessel is closed to prevent water loss, and the medium is heated while stirring continuously. The following elastomer test specimens are exposed to an oil-water emulsion under the following measuring conditions: FKM: 80 FKM 10061: 336 h / 80 °C

[0122] After the contact time in the pure lubricating oil or oil-water emulsion has elapsed, the specimens are allowed to cool and cleaned. Changes in hardness, weight, volume, tensile strength, and / or elongation at break of the elastomers after immersion in the lubricant are then determined according to the applicable standards compared to the as-delivered condition: Change in volume, change in weight: Determination is carried out according to DIN ISO 1817 (DIN ISO 1817:2016-11) Elastomers - Determination of behavior towards liquids

[0123] The change in the volume or weight of the test specimens provides information about the migration of the test liquid into the interior of the material or the dissolution or possibly even dissolution of the material. Change in Shore A hardness: Determination is carried out according to DIN ISO 7619-1 (DIN ISO 7619-1:2012-02) Rubber or thermoplastic elastomers - Determination of penetration depth - Part 1: Durometer method (Shore hardness)

[0124] Hardness is generally defined as the mechanical resistance of a material when penetrated by a harder test specimen. Change in tensile strength and elongation at break: Determination is carried out according to DIN 53504 (DIN 53504:2017-03) - Testing of rubber and elastomers - Determination of tensile strength, elongation at break and stress values ​​in the tensile test

[0125] The measurement results of the static elastomer incorporation in pure lubricating oil are given in the following Tables 1 to 3: Table 1a (80 FKM 10061 / 150 °C / 168 h): parameter Example 1 Example 2 Example 3 Comparison example 1 Weight change, % 0,3 0,4 0,4 Not measurable Volume change, % 0,9 0,5 0,5 Not measurable Change in Shore A hardness 0 0 0 Not measurable Change in tensile strength, % -2 6 9 Not measurable Change at break, % -16 17 21 Not measurable Table 1b (85 FKM 245601 / 150 °C / 168 h): parameter Example 1 Example 2 Example 3 Comparison example 1 Weight change, % 0,1 0,1 0,1 Not measurable Volume change, % 0,2 0,3 0,2 Not measurable Change in Shore A hardness 0 -1 -1 Not measurable Change in tensile strength, % -8 -8 -11 Not measurable Change at break, % -6 -5 -9 Not measurable

[0126] As can be seen from Tables 1a and 1b, after immersion in the inventive lubricant compositions of Examples 1, 2, and 3, each containing an OSP, an antioxidant, and a neutral corrosion inhibitor, the test specimens exhibit only minor changes in volume, weight, Shore A hardness, tensile strength, and elongation at break, indicating good elastomer compatibility of the lubricant compositions. In contrast, the lubricant composition according to Comparative Example 1, which contains an OSP and a neutral corrosion inhibitor but no antioxidant, does not produce any measurable results, as the lubricant composition begins to decompose under the selected conditions even before the end of the test. The results demonstrate a synergistic effect between the components of the inventive lubricants. Table 2 (80 FKM 10061 / 150 °C / 168 h): parameter Example 1 See Example 2 See Example 3 See Example 4 See Example 5 See Example 6 Change in tensile strength, % -2 -25 -21 -24 -9 -12 Change at break, % -16 -46 -40 -52 -42 -44

[0127] As can be seen from Table 2, after immersion in the inventive lubricant composition from Example 1, which contains an OSP, an antioxidant, and a neutral corrosion inhibitor (TAN < 10 mg KOH / g), the test specimen exhibits significantly smaller changes in tensile strength and elongation at break compared to immersion in the lubricant compositions of the comparative examples, which contain acidic corrosion inhibitors in addition to OSP and antioxidants (TAN > 100 mg KOH / g). The results demonstrate a synergistic effect between the components of the inventive lubricant in that elastomer compatibility can be improved by selecting a suitable corrosion inhibitor. Table 3 (ISO 6072 NBR 1 / 100 °C / 1000 h): parameter Example 1 Example 4 Weight change, % 4,8 5,8 Volume change, % 5,6 6,5 Change in Shore A hardness, 1 -2 Change in tensile strength, % -28 -18 Change at break, % -54 -40

[0128] As can be seen from Table 3, the test specimens exhibit comparable changes in weight, volume, and Shore A hardness after immersion in the inventive lubricant compositions from Examples 1 and 4, whereas immersion in the lubricant composition from Example 4 leads to a smaller change in the tensile strength and elongation at break of the test specimen. The results show that increasing the proportion of OSP in the lubricant composition according to Example 4 leads to a further increase in the compatibility of the lubricant composition with NBR.

[0129] The measurement results of the static elastomer incorporation in oil-water emulsions are given in Table 4 below: Table 4 (80 FKM 10061 / Oil+5% Water; 80 °C; 336 h) parameter Example 1 Example 3 Example 5 See Example 7 See Example 8 See Example 9 See Example 10 See Example 11 Weight change, % 2,2 2,3 2,7 7,9 6,1 11,6 4,3 8,2 Volume change, % 3,1 2,8 3,8 13,9 10,6 20,5 6,6 14,2

[0130] As can be seen from Table 4, in contrast to Comparative Examples 7-11, only slight changes in the weight and volume of the test specimen were observed for the inventive lubricant compositions of Examples 1, 3, and 5, which contain both an ester and an OSP as base oil components, indicating increased elastomer compatibility. In particular, a comparison of the measurement results with the formulations from Comparative Examples 7, 8, and 9, which contain only esters as the base oil component, with otherwise identical additives (see in particular Example 1 / Comparative Example 8, Example 3 / Comparative Example 9, Example 5 / Comparative Example 7), shows that the absence of an OSP leads to poorer values ​​with regard to the weight change and, in particular, volume change of the test specimen, and thus to reduced elastomer compatibility.The formulations of Comparative Examples 10 and 11 contain a basic corrosion inhibitor.

Claims

1. Lubricant composition comprising - an oil-soluble polyalkylene glycol in an amount of 10-70% by weight, based on the overall lubricant composition; - an ester compound selected from the group of natural esters and synthetic esters, and combinations thereof, in an amount of 15-85% by weight, based on the overall lubricant composition; and - an additive mixture comprising an antioxidant and an anticorrosive, wherein the anticorrosive is selected from neutral alkali metal and alkaline earth metal salts of sulfonic acids, carboxylic acids, naphthoic acids, naphthenic acids, benzoic acids and phosphoric acids, and combinations thereof, wherein the neutral alkali metal and alkaline earth metal salts are Na, Ca, K and Mg salts, wherein the oil-soluble polyalkylene glycol is a copolymer selected from polybutylene oxide-polypropylene oxide copolymers, polybutylene oxide-polyethylene oxide copolymers and polybutylene oxide-polypropylene oxide-polyethylene oxide copolymers, and combinations thereof, and wherein the oil-soluble polyalkylene glycol has a molecular weight Mn of 500 g / mol or more to 1400 g / mol or less.

2. Lubricant composition according to Claim 1 or 2, wherein the anticorrosive is selected from neutral calcium sulfonates.

3. Lubricant composition according to one of Claims 1 to 3, wherein the antioxidant is selected from phenolic antioxidants, aminic antioxidants, phosphites and sulfur-containing compounds, and combinations thereof, wherein the sulfur-containing compounds are selected from alkyl and aryl sulfides, sulfur-containing phenol compounds and sulfur-containing carboxylic acids, phosphorothionates, thiocarbamates and dithiocarbamates, thiophosphates and thiopropionates.

4. Lubricant composition according to one of Claims 1 to 3, wherein the antioxidant is selected from phenolic antioxidants, aminic antioxidants, thiocarbamates and dithiocarbamates, and combinations thereof.

5. Lubricant composition according to one of Claims 1 to 4, wherein the antioxidant is selected from aminic antioxidants.

6. Lubricant composition according to one of Claims 1 to 5, wherein the additive mixture further comprises a nonferrous metal deactivator selected from triazoles and mercaptothiadiazoles, and combinations thereof.

7. Lubricant composition according to Claim 6, wherein the nonferrous metal deactivator is selected from triazoles.

8. Lubricant composition according to one of Claims 1 to 7, wherein the ester compound is selected from natural glyceride esters, especially from the group of sunflower oil, rapeseed oil or colza oil, linseed oil, corn oil, safflower oil, soybean oil, linseed oil, peanut oil, "lesquerella" oil, palm oil, olive oil, in monomeric, oligomeric and / or polymerized form; and synthetic esters from the group of polyol esters, polyol complex esters, complex esters of dimer acids, dimer acid esters, aliphatic carboxylic acid and dicarboxylic esters, phosphate esters and trimellitic and pyromellitic esters and estolides; and combinations thereof.

9. Lubricant composition according to one of Claims 1 to 8, wherein the ester compound is selected from polyol esters and polyol complex esters, and combinations thereof.

10. Lubricant composition according to one of Claims 1 to 9, wherein the ester compound is selected from neopentyl glycol esters, trimethylolpropane esters and pentaerythritol esters that have been esterified with saturated and / or mono- or polyunsaturated, linear and / or branched monocarboxylic acids of chain length C4-C36; and neopentyl glycol complex esters, trimethylolpropane complex esters and pentaerythritol complex esters that have been fully esterified or partly esterified with saturated and / or mono- or polyunsaturated, linear and / or branched monocarboxylic acids of chain length C4-C36 and with saturated and / or mono- or polyunsaturated, linear and / or branched dicarboxylic acids of chain length C4-C36 in any mixture; and combinations thereof.

11. Lubricant composition according to Claim 10, wherein the neopentyl glycol esters, trimethylolpropane esters and pentaerythritol esters have each been esterified with saturated and / or mono- or polyunsaturated, linear and / or branched monocarboxylic acids of chain length C18-C36; and the neopentyl glycol complex esters, trimethylolpropane complex esters and pentaerythritol complex esters have each been fully esterified or partly esterified with saturated and / or mono- or polyunsaturated, linear and / or branched monocarboxylic acids of chain length C18-C36 and with saturated and / or mono- or polyunsaturated, linear and / or branched dicarboxylic acids of chain length C4-C36 in any mixture.

12. Lubricant composition according to one of Claims 1 to 11, wherein the oil-soluble polyalkylene glycol is a copolymer selected from polyisobutylene oxide-polyisopropylene oxide copolymers, polyisobutylene oxide-polyethylene oxide copolymers and polyisobutylene oxide-polyisopropylene oxide-polyethylene oxide copolymers, and combinations thereof.

13. Lubricant composition according to one of Claims 1 to 12, wherein the oil-soluble polyalkylene glycol copolymer is an alcohol-initiated copolymer, and especially a copolymer having a C10-C20-alkyl radical bonded to at least one terminal end thereof.

14. Lubricant composition according to one of Claims 1 to 13, wherein the additive mixture is present in an amount of 0.1-20% by weight, based on the overall lubricant composition.

15. Lubricant composition according to one of Claims 1 to 14, wherein the additive mixture further comprises one or more additives selected from antiwear agents, friction modifiers, high-pressure additives, ion complex formers, solid lubricants, dispersants, pour point and viscosity improvers, UV stabilizers, emulsifiers, color indicators, lubricity improvers and defoamers.

16. Use of a lubricant composition according to one of Claims 1 to 15 as gear oil, roller bearing oil, hydraulic oil or slide bearing oil in the marine sector and in inland waterways, especially for lubrication of gears, hydraulics, propeller rudders, propeller shafts, linear guides, pneumatic components, instruments, bearings, such as slide, roller or stern tube bearings, chains, cables, springs, valves and propellers in machines, machine components and systems that come into contact with water and in machines and machine elements on land that may come into contact with water and / or aqueous media.