Use of hemimellitic acid esters as base oils in lubricant compositions

Abstract

The present invention relates to the use of a hemimellitic acid ester of the following general formula I, in which R1, R2 and R3 are each independently a) an unsubstituted branched or unbranched C1-C20 alkyl group, or b) a C1-C5 alkyl group having at least one substituent selected from the group consisting of a cycloalkyl group and an aromatic group, or c) a C5-C20 aromatic group or a C5-C20 cycloalkyl group, as a base oil in a lubricant composition for the lubrication of tribological systems, wherein the hemimellitic acid ester of formula I can be present as a mixture of various compounds of formula I.

Description

[Technical Field]

[0001] The present invention relates to the use of hemimellitic esters as base oils in lubricant compositions, and to lubricant compositions based on hemimellitic esters as base oils.

[0002] Lubricants are essential components in many industrial processes where two or more surfaces move in close contact. The range of applications for lubricants is very wide and includes, among others, automotive lubricants, lubricants for two-stroke and four-stroke gasoline engines, lubricants for diesel engines, gas engine oils, gas turbine oils, automatic transmission fluids, and gear oils.

[0003] Lubricants can be lubricating oils and lubricating greases. Industrial lubricants include, inter alia, industrial gear oils, lubricants for pneumatic tools, high-temperature oils, air and gas compressor oils for all types of compressors, machine tool oils, textile oils, steam turbine oils, hydraulic oils, paper machine oils, food machine oils, steam cylinder oils, metalworking oils for metal cutting, metal rolling, metal drawing, metal forging, and metal casting. Lubricating greases further contain one or more thickeners in addition to the lubricating oil.

[0004] Considering the sustainability of lubricants, it is desirable for the lubricant to contain at least a partially bio-based base oil. Furthermore, it is practically advantageous for the lubricant to contain a base oil that can be obtained (at least in part) from both biological and petrochemical sources. This allows for both high flexibility in lubricant manufacturing and the potential to provide environmentally friendly and sustainable lubricants. However, many bio-based oils are not suitable for lubricant applications because they do not have the desired property profile, for example, with regard to oxidation stability and low-temperature behavior.

[0005] The use of trimellitic esters as lubricant base oils is known and in practice, but these esters are not currently available on an industrial scale from biological sources.

[0006] From WO 2012159738 a high-temperature oil is known for lubricating chains, chain rollers and belts of continuous presses, which high-temperature oil comprises an ester of the general formula (II) [ka] The compounds contain 40-91.9 wt. % of the compound [wherein R is a linear or branched alkyl group having a chain length of 8-16 carbon atoms] and 5-50 wt. % of hydrogenated polyisobutylene, fully hydrogenated polyisobutylene, or a mixture of fully hydrogenated and hydrogenated polyisobutylene. The described two-component systems have excellent performance in terms of thermal stability, residue formation, and residue behavior. However, this ester is not currently available on an industrial scale from biological sources.

[0007] The present invention provides a base oil for a lubricant composition that can be obtained from both biological and petrochemical sources. Furthermore, it is desirable that the resulting lubricant composition have good oxidation stability, lubricating effectiveness, and good low-temperature behavior. It is also desirable that the lubricant composition exhibit good lubricating effectiveness over an extended period of time, even at a constant high temperature. It is also desirable that the lubricant composition be available in a variety of viscosities depending on the desired application.

[0008] According to the present invention, this problem is solved by providing a compound of the following general formula I [ka] [In the formula, R1, R2 and R3 are, independently of one another, a) an unsubstituted branched or unbranched C1 to C20 alkyl group, or b) a C1-C5 alkyl group having at least one substituent selected from the group consisting of a cycloalkyl group and an aromatic group, or c) a C5-C20 aromatic group or a C5-C20 cycloalkyl group The problem is solved by the use of a hemimellitic acid ester of formula I, wherein the hemimellitic acid ester is a base oil for a lubricant composition for the lubrication of tribological systems, wherein the hemimellitic acid ester can be present as a mixture of various compounds of formula I.

[0009] It has been surprisingly found that the use of the hemimellitic acid ester of Formula I above as a base oil makes it possible to obtain a lubricant composition having good oxidation stability, lubricating effect, and good low-temperature behavior. Furthermore, the lubricant composition exhibits good lubricating properties over a long period of time, even at high temperatures. Furthermore, the lubricant composition can be provided in a variety of viscosities depending on the desired application. This is surprising because, although hemimellitic acid esters can be obtained from biological sources, as explained above, bio-based lubricants typically do not have the desired range of properties in terms of oxidation stability, lubricating effect, and low-temperature behavior.

[0010] The production of hemimellitic esters from biomass is known and is described, for example, in U.S. Patent No. 10,562,875. Depending on the feedstock used, the resulting hemimellitic esters may have a high percentage of biobased carbon or may be entirely biobased. However, hemimellitic esters can also be readily obtained from petroleum and petrochemical sources, allowing for greater flexibility in lubricant production.

[0011] In a preferred embodiment, the hemimellitic acid esters are at least partially biobased. This means that the hemimellitic acid esters are produced at least partially from raw materials derived from biological sources and / or renewable agricultural materials (including plant materials, animal materials, and marine materials) rather than from petroleum or petrochemical sources. Exemplary biological sources are agricultural, forestry, plant cultivation, or animal materials. Preferred biological sources are straw, animal waste, agricultural waste, and forestry waste.

[0012] In the lubricant composition, the hemimellitic esters can be present as the sole base oil or in mixtures with other base oils.

[0013] A tribological system is a technical configuration whose function is realized by structural elements that are mechanically moved and thus subject to friction and wear. Tribological systems are responsible for converting, transporting, and making technically usable motion, energy, and matter. Preferred tribological systems are those made of metallic and / or non-metallic materials, such as rolling and plain bearings, especially in vehicle technology, conveyor technology, mechanical engineering, and / or office technology; gears, chains, sliding guides, and joints, especially wheel bearings for automobiles; wind turbine bearings, especially wind turbine rotor bearings; and / or rotary plain bearings, such as fan bearings, or linear guide plain bearings and / or ball joints, especially ball joints used in the automotive sector. Possible tribological systems also include sliding partners in industrial plants and machines, as well as sliding partners in household machinery and household appliances, especially in oil-lubricated systems, for the lubrication of chains, chain rollers, and steel belts in continuous wood presses.

[0014] In a preferred embodiment, the tribological system has surfaces comprising metallic and / or non-metallic materials, advantageously composite materials, aluminium, aluminium alloys, steel, stainless steel and cast materials, non-ferrous metals, plastics, fibre reinforced plastics and / or polymers.

[0015] In a preferred embodiment of the present invention, the lubricant composition contains at least 10 wt. %, e.g., 10-100 wt. % and / or 10-95 wt. %, advantageously at least 15 wt. %, e.g., 15-95 wt. %, particularly at least 20 wt. %, e.g., 20-95 wt. %, of biobased carbon, based on the total weight of organic carbon in the lubricant composition. The biobased carbon content can be measured using ASTM International Radioisotope Standard Method D 6866. The latest version of this standard as of the filing date applies. In this method, the biobased content of a material is determined based on the amount of biobased carbon in the material as a percentage of the weight of the total organic carbon in the material. This method relies on the fact that biobased carbon isotope ratios, 13C / 12C and 14C / 12C, which differ from those found in petroleum-derived materials.

[0016] In a further preferred embodiment of the invention, the hemimellitic ester of formula I comprises at least 30 wt. %, such as 30 to 100 wt. %, advantageously at least 40 wt. %, such as 40 to 100 wt. %, and in particular at least 50 wt. %, such as 50 to 100 wt. %, of bio-based carbon, based on the total weight of the hemimellitic ester of formula I in the lubricant composition, each measured using ASTM International Radioisotope Standard Method D 6866. The latest edition of this standard as of the filing date applies.

[0017] In a further preferred embodiment of the invention, the acid component of the hemimellitic ester of formula I comprises at least 30 wt. %, such as 30 to 100 wt. %, advantageously at least 40 wt. %, such as 40 to 100 wt. %, and in particular at least 50 wt. %, such as 50 to 100 wt. %, of bio-based carbon, based on the total weight of the acid component of the hemimellitic ester of formula I in the lubricant composition, each measured using ASTM International Radioisotope Standard Method D 6866. The latest edition of this standard as of the filing date applies.

[0018] In a preferred embodiment of the invention, at least one group R1, R2 and / or R3 is an unsubstituted branched or unbranched C1 to C20 alkyl group, even more preferably a C5 to C20 alkyl group, even more preferably a C6 to C18 alkyl group, in particular a C8 to C18 alkyl group.

[0019] In a further particularly preferred embodiment of the present invention, at least one group R1, R2 and / or R3 is selected from the group consisting of octanyl, ethylhexanyl, nonanyl, decanyl, undecanyl, dodecanyl.

[0020] In a further particularly preferred embodiment of the present invention, at least one group R1, R2 and / or R3 is selected from the group consisting of octanyl, 2-ethylhexan-1-yl, 1-nonanyl, decanyl, 1-undecanyl, 1-dodecanyl.

[0021] In a further preferred embodiment of the present invention, at least one group R1, R2 and / or R3 is a C1-C5 alkyl group, advantageously a C1-C3 alkyl group, even more preferably a C1-C2 alkyl group, in particular a C1 alkyl group, each of which carries at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups. In this embodiment, the aforementioned number of carbon atoms of the alkyl group does not include the number of carbon atoms of the substituents. Here, according to the present invention, cycloalkyl groups include both monocyclic and polycyclic compounds.

[0022] Advantageously, the substituents have, independently of one another, 5 to 19 carbon atoms, even more preferably 5 to 17 carbon atoms, in particular 5 to 15 carbon atoms. More preferably, the substituents are, independently of one another, selected from a C5 to C19 cycloalkyl group or a C5 to C19 aromatic group, even more preferably from a C5 to C17 cycloalkyl group or a C5 to C17 aromatic group, in particular from a C5 to C15 cycloalkyl group or a C5 to C15 aromatic group.

[0023] In a further preferred embodiment of the present invention, at least one radical R1, R2 and / or R3 is a methyl, ethyl or propyl radical substituted with at least one cycloalkyl radical having 5 to 15 carbon atoms or at least one aromatic radical having 5 to 15 carbon atoms, in particular 5 to 10 carbon atoms. Particularly preferably, R1, R2 and R3 are each independently a methyl radical substituted with at least one cycloalkyl radical having 5 to 15 carbon atoms or at least one aromatic radical having 5 to 15 carbon atoms, in particular 5 to 10 carbon atoms.

[0024] In a further embodiment of the invention, at least one group R1, R2 and / or R3 is a C5-C20 aromatic group or a C5-C20 cycloalkyl group. Advantageously, at least one group R1, R2 and / or R3 is selected from phenyl, cyclopentyl, cyclohexyl, naphthyl, isotridecyl, tricyclodecanemethyl, furfuryl.

[0025] In a particularly preferred embodiment of the present invention, at least one group R1, R2 and / or R3, preferably at least two groups R1, R2 and / or R3, in particular all groups R1, R2 and R3, are selected from the group consisting of octanyl, ethylhexanyl, nonanyl, decanyl, undecanyl, dodecanyl, isotridecyl, tricyclodecanemethyl, furfuryl.

[0026] In a further particularly preferred embodiment of the present invention, at least one group R1, R2 and / or R3, preferably at least two groups R1, R2 and / or R3, in particular all groups R1, R2 and R3, are selected from the group consisting of octanyl, 2-ethylhexan-1-yl, 1-nonanyl, decanyl, 1-undecanyl, 1-dodecanyl, isotridecyl, tricyclodecanemethyl, furfuryl.

[0027] The groups R1, R2 and R3 may be the same or different.

[0028] In a further preferred embodiment, the hemimellitic ester of formula I has groups R1, R2 and R3 that are at least partially different from each other. Also preferably, the hemimellitic ester of formula I is a mixture of various compounds of formula I.

[0029] Also preferably, the groups R1, R2 and R3, independently of one another, contain no atoms other than carbon and hydrogen.

[0030] In a preferred embodiment of the invention, the lubricant composition comprises the hemimellitic ester of formula I in an amount of 20% to 90% by weight, even more preferably 25% to 70% by weight, even more preferably 25% to 60% by weight, and especially 30% to 50% by weight, each relative to the total weight of the lubricant composition.

[0031] In a further preferred embodiment of the present invention, the hemimellitic acid ester of formula I is 2 / s~150mm 2 / s, advantageously 30 mm 2 / s~100mm 2 / s, and even more preferably 50 mm 2 / s~150mm 2 / s, especially 50mm 2 / s~90mm 2 / s range of kinematic viscosity [mm 2 / sec].

[0032] In a further preferred embodiment of the present invention, the lubricant composition is present as an oil formulation and has a viscosity of 100 mm at 40° C. 2 / s~460mm 2 / s, advantageously 150 mm 2 / s~320mm 2 / s range of kinematic viscosity [mm 2 / sec].

[0033] In a further preferred embodiment of the present invention, the lubricant composition is present as a grease formulation, wherein the hemimellitic acid ester of formula I and / or a mixture of the hemimellitic acid ester of formula I with a further base oil has a viscosity of 80 mm at 40° C. 2 / s~460mm 2 / s, advantageously 100 mm 2 / s~320mm 2 / s range of kinematic viscosity [mm 2 / sec].

[0034] In a further preferred embodiment of the present invention, the lubricant composition comprises 5 to 50 wt. %, even more preferably 15 to 35 wt. %, and especially 15 to 30 wt. % of polyisobutylene, based on the total weight of the lubricant composition. The advantage of using polyisobutylene is that the viscosity of the lubricant composition can be particularly easily adjusted using polyisobutylene. Furthermore, in combination with the hemimellitic acid ester of formula I, particularly good residue behavior after complete evaporation can be achieved. According to a preferred embodiment, the polyisobutylene has a number-average molecular weight of 115 to 15,000 g / mol, advantageously 160 to 5,000 g / mol, as measured according to DIN 55672-1:2016-03 (Gel Permeation Chromatography (GPC)—Part 1: Tetrahydrofuran (THF) as Eluent).

[0035] As already explained above, the lubricant composition can exist as both a grease formulation and an oil formulation.

[0036] When the lubricant composition is present as a grease formulation, it contains a thickener. Thus, in a preferred embodiment of the present invention, the lubricant composition contains 3 to 30 wt % of a thickener.

[0037] The thickener is advantageously a reaction product of a diisocyanate, advantageously 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanatodiphenylmethane, 2,4'-diisocyanatophenylmethane, 4,4'-diisocyanatodiphenyl, 4,4'-diisocyanato-3,3'-dimethylphenyl, 4,4'-diisocyanato-3,3'-dimethylphenylmethane, which can be used alone or in combination, with an amine of general formula R'-NR or a diamine of general formula R'-NR-NR', or a mixture of amines and diamines, where R is an aryl, alkyl or alkylene group having 2 to 22 carbon atoms and R', identical or different, is hydrogen, an alkyl, alkylene or aryl group.

[0038] In a further preferred embodiment, the thickener is selected from Al complex soaps, simple metal soaps of elements of the first and second main groups of the periodic table, complex metal soaps of elements of the first and second main groups of the periodic table, bentonite, sulfonates, silicates, aerosil, polyimides or PTFE, or mixtures of the aforementioned thickeners.

[0039] In addition to the hemimellitic ester of Formula I, the lubricant composition may further comprise at least one additional base oil.

[0040] If the lubricant composition is present as an oil formulation and comprises at least one further base oil, the proportion of the further base oil is advantageously from 10% to 50% by weight, even more preferably from 10% to 40% by weight, even more preferably from 20% to 40% by weight, and in particular from 25% to 40% by weight, each relative to the total weight of the lubricant composition.

[0041] If the lubricant composition is present as a grease formulation and comprises at least one further base oil, the proportion of said further base oil(s) is advantageously between 10% and 50% by weight, even more preferably between 25% and 50% by weight, in particular between 30% and 50% by weight, each relative to the total weight of the lubricant composition.

[0042] When the lubricant composition further comprises at least one further base oil, the lubricant composition preferably comprises the hemimellitic ester of formula I in an amount of 20 wt. % to 70 wt. %, even more preferably 25 wt. % to 70 wt. %, even more preferably 25 wt. % to 60 wt. %, and especially 30 wt. % to 50 wt. %, each relative to the total weight of the lubricant composition.

[0043] Suitable further base oils are conventional lubricating oils that are liquid at room temperature (20°C). The further base oils are advantageously 18mm thick at 40°C. 2 / s~20000mm 2 / s, especially 30mm 2 / s~400mm 2 Base oils have a kinematic viscosity of 1 / s. A distinction is made between mineral oils and synthetic oils. Base oils are base oils commonly used in the manufacture of lubricants, particularly those that can be classified as Group I, II, II+, III, IV, or V according to the American Petroleum Institute (API) classification [NLGI Spokesman, N. Samman, Volume 70, Number 11, S. 14ff]. Mineral oils are classified by API group. API Group I includes mineral oils, such as naphthenic and paraffinic oils. When these mineral oils are chemically improved compared to API Group I oils, resulting in lower aromatics, lower sulfur content, and a lower proportion of saturates, thereby improving viscosity / temperature behavior, they are classified into API Groups II and III. API Group III also includes so-called gas-to-liquid oils, which are produced by chemical reactions of natural gas rather than by refining crude oil. Furthermore, refrigerants can also be used.

[0044] Synthetic oils include polyethers, esters, polyesters, preferably poly-α-olefins, especially metallocene poly-α-olefins, perfluoropolyalkyl ethers (PFPAE), alkylated naphthalenes, silicone oils, and alkyl aromatic compounds, and mixtures thereof.Polyether compounds can have free hydroxyl groups, but can also be completely etherified, or end groups can be esterified, and / or can be produced from starting compounds with one or more hydroxyl groups and / or carboxyl groups (-COOH).Polyphenyl ethers can also be used as a single component, or better still, as a mixed component.

[0045] Suitable esters that can be used are esters of aromatic and / or aliphatic di-, tri- or tetracarboxylic acids with one or a mixture of C7 to C22 alcohols, esters of trimethylolpropane, pentaerythritol or dipentaerythritol with aliphatic C7 to C22 carboxylic acids, esters of C18 dimer acids with C7 to C22 alcohols, complex esters, either as individual components or in any mixture. Triglycerides and / or estolides are also preferred esters.

[0046] Silicone oils, native oils and derivatives of native oils are also suitable.

[0047] Further base oils which are particularly preferred according to the invention are esters, in particular esters of aromatic and / or aliphatic di-, tri- or tetracarboxylic acids with one or a mixture of C7 to C22 alcohols, esters of trimethylolpropane, pentaerythritol or dipentaerythritol with aliphatic C7 to C22 carboxylic acids, esters of C18 dimer acids with C7 to C22 alcohols, complex esters, either as individual components or in any mixture, and also triglycerides and / or estolides, poly-α-olefins, polyethers and / or mineral oils.

[0048] Furthermore, the lubricant composition may contain an inorganic or organic solid lubricant in a proportion advantageously between 0.1% and 5% by weight, preferably between 0.1% and 3% by weight, relative to the total weight of the lubricant composition, whereby a solid lubricant selected from PTFE, BN, pyrophosphate, Zn oxide, Mg oxide, pyrophosphate, thiosulfate, Mg carbonate, Ca carbonate, Ca stearate, Zn sulfide, Mo sulfide, W sulfide, Sn sulfide, graphite, graphene, nanotubes, SiO2 modifications or mixtures thereof is preferred.

[0049] More preferably, the lubricant composition comprises 0.1 to 8 wt. % of an additive selected from the group consisting of anti-corrosion additives, antioxidants, anti-wear additives, metal deactivators, ion complexing agents and / or UV stabilizers.

[0050] Particularly suitable antioxidants according to the invention are the following compounds: styrenated diphenylamines, diaromatic amines, phenolic resins, thiophenolic resins, phosphites, butylated hydroxytoluene, butylated hydroxyanisole, phenyl-α-naphthylamine, phenyl-β-naphthylamine, octylated / butylated diphenylamine, di-α-tocopherol, di-tert-butylphenyl, benzenepropanoic acid, sulfur-containing phenolic compounds and mixtures of these components.

[0051] Similarly suitable antioxidants are compounds containing sulfur, nitrogen and / or phosphorus in the molecule. Preferred compounds containing sulfur, nitrogen and / or phosphorus in the molecule are selected from the group consisting of aromatic amine antioxidants, such as alkylated phenyl-α-naphthylamines, dialkyldiphenylamines, sterically hindered phenols, such as butylhydroxytoluene (BHT), phenolic antioxidants having a thioether group, Zn-, Mo- or W-dialkyldithiophosphates and phosphites.

[0052] Preferred corrosion inhibitors, metal deactivators and / or ion complexing agents are triazoles, imidazolines, N-methylglycine (sarcosine), benzotriazole derivatives, N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine; n-methyl-N(1-oxo-9-octadecenyl)glycine, mixtures of phosphoric acid and mono- and diisooctyl esters reacted with (C11-14) alkylamines, mixtures of phosphoric acid and mono- and diisooctyl esters reacted with tertiary alkylamines and primary (C12-14) amines, dodecanoic acid, triphenylphosphorothionate and amine phosphates, and mixtures thereof. Commercially available additives are: IRGAMET® 39, IRGACOR® DSS G, Amin O; SARKOSYL® O (Ciba), COBRATEC® 122, CUVAN® 303, VANLUBE® 9123, Cl-426, Cl-426EP, Cl-429, and Cl-498.

[0053] Preferred antiwear additives according to the present invention are amines, amine phosphates, phosphates, thiophosphates, phosphorothioates and mixtures of these components. Preferred antiwear additives are selected from the group consisting of antiwear additives based on diphenyl cresyl phosphate, amine-neutralized phosphate, alkylated and non-alkylated triaryl phosphates, alkylated and non-alkylated triaryl thiophosphates, zinc or Mo or W-dialkyldithiophosphates, carbamates, thiocarbamates, zinc or Mo or W-dithiocarbamates, dimercaptothiadiazole, calcium sulfonate and benzotriazole derivatives. Commercially available anti-wear additives include IRGALUBE® TPPT, IRGALUBE® 232, IRGALUBE® 349, 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.

[0054] Further subject matter of the present invention is the following: from 20% to 90% by weight, advantageously from 50% to 85% by weight, of a compound of general formula I below as base oil [ka] [In the formula, R1, R2 and R3 are, independently of one another, a) a branched or unbranched C1 to C20 alkyl group, or b) a C1-C5 alkyl group having at least one substituent selected from the group consisting of a cycloalkyl group and an aromatic group, or c) a C5-C20 aromatic group or a C5-C20 cycloalkyl group wherein the hemimellitic acid ester of formula I can exist as a mixture of various compounds of formula I; - 5% to 50% by weight, advantageously 10% to 50% by weight, of polyisobutylene, - 0.1% to 8% by weight of additives and a lubricant composition formed as an oil formulation comprising:

[0055] In a further preferred embodiment, the lubricant composition formed as an oil formulation further comprises from 10% to 45% by weight, advantageously from 30% to 45% by weight, of at least one further base oil.

[0056] Further subject matter of the present invention is the following: from 20% to 90% by weight, advantageously from 30% to 90% by weight, and even more preferably from 40% to 90% by weight, of a compound of general formula I below as base oil [ka] [In the formula, R1, R2 and R3 are, independently of one another, a) a branched or unbranched C1 to C20 alkyl group, or b) a C1-C5 alkyl group having at least one substituent selected from the group consisting of a cycloalkyl group and an aromatic group, or c) a C5-C20 aromatic group or a C5-C20 cycloalkyl group wherein the hemimellitic acid ester of formula I can exist as a mixture of various compounds of formula I; - 3 to 30% by weight of a thickener, - 0.1 to 8% by weight of additives and a lubricant composition formed as a grease formulation comprising:

[0057] Further subject matter of the present invention is the following: from 20% to 70% by weight, advantageously from 30% to 70% by weight, and even more preferably from 40% to 70% by weight, of a compound of general formula I below as base oil [ka] [In the formula, R1, R2 and R3 are, independently of one another, d) a branched or unbranched C1 to C20 alkyl group, or e) a C1-C5 alkyl group having at least one substituent selected from the group consisting of a cycloalkyl group and an aromatic group, or f) a C5-C20 aromatic group or a C5-C20 cycloalkyl group wherein the hemimellitic acid ester of formula I can exist as a mixture of various compounds of formula I; - 3 to 30% by weight of a thickener, - 10% to 50% by weight of at least one further base oil, - 0.1 to 8% by weight of additives and a lubricant composition formed as a grease formulation comprising:

[0058] In a preferred embodiment, the lubricant composition formed as a grease formulation comprises 10% to 40% by weight polyisobutylene.

[0059] In a further preferred embodiment, the lubricant composition formed as a grease formulation comprises 0.1% to 5% by weight of an inorganic or organic solid lubricant.

[0060] Preferred components of the lubricant composition according to the invention are those mentioned in connection with the use according to the invention.

[0061] Particularly preferred thickeners, especially for lubricant compositions formulated as grease formulations, are reaction products of diisocyanates, advantageously 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanatodiphenylmethane, 2,4'-diisocyanatophenylmethane, 4,4'-diisocyanatodiphenyl, 4,4'-diisocyanato-3,3'-dimethylphenyl, 4,4'-diisocyanato-3,3'-dimethylphenylmethane, which may be used alone or in combination, with amines of the general formula R'-NR or diamines of the general formula R'-NR-NR', or mixtures of amines and diamines, where R is an aryl, alkyl or alkylene group having 2 to 22 carbon atoms and R', whether identical or different, is hydrogen, an alkyl, alkylene or aryl group.

[0062] In a further preferred embodiment, the thickener is selected from Al complex soaps, simple metal soaps of elements of the first and second main groups of the periodic table, complex metal soaps of elements of the first and second main groups of the periodic table, bentonite, sulfonates, silicates, aerosil, polyimides or PTFE, or mixtures of the aforementioned thickeners.

[0063] Further base oils which are particularly preferred for the lubricant composition according to the invention, whether formulated as a grease formulation or as an oil formulation, are esters, in particular esters of aromatic and / or aliphatic di-, tri- or tetracarboxylic acids with one or a mixture of C7 to C22 alcohols, esters of trimethylolpropane, pentaerythritol or dipentaerythritol with aliphatic C7 to C22 carboxylic acids, esters of C18 dimer acids with C7 to C22 alcohols, complex esters, either as individual components or in any mixtures, as well as triglycerides and / or estolides, poly-α-olefins, polyethers and / or mineral oils. [Brief explanation of the drawings]

[0064] [Figure 1]FIG. 1 shows the kinematic viscosity of hemimellitic esters of Formula I compared to trimellitic esters versus temperature. [Figure 2] FIG. 1 shows the average friction as determined by SRV versus temperature for several lubricant compositions containing a hemimellitic ester of Formula I in accordance with the present invention compared to a lubricant composition containing a trimellitic ester.

[0065] Measurement method viscosity: Viscosity measurements are carried out using a Stabinger SVM 3000 viscometer (Anton Paar) in accordance with DIN 51562 (2018).

[0066] Biobased Carbon Content: Biobased carbon content is measured using ASTM International Radioisotope Standard Method D 6866 (version in effect as of the filing date).

[0067] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0068] Example 1: Measurement of the kinematic viscosity of the hemimellitic ester of formula I compared to the trimellitic ester Hemimellitic acid ester 1 is prepared by the following reaction: [ka]

[0069] Example 1-A: A mixture of 150 g of biobased hemimellitic acid, 369.6 g of Nafol 810D, and 60 mL of xylene in a 1 L three-neck flask coupled with a water separator is refluxed at 1 atm. The internal temperature rises from 126 °C to 200 °C within 4 hours, and 0.52 g of tetraisopropyl orthotitanate (0.1 wt%) is added at an internal temperature of 160 °C. The clear reaction mixture is then refluxed at 200 °C for 2 hours, continuously distilling off a total of 38.8 g of water. Xylene and excess alcohol are distilled off under reduced pressure (T 内部 = 200°C, 10 mbar). After removing the catalyst, the product (407.7 g) is obtained as a pale yellow oil.

[0070] Example 1-B: A mixture of 150 g of biobased hemimellitic acid, 369.6 g of Nafol 810D, and 45 mL of xylene in a 1 L three-neck flask coupled with a water separator is refluxed at 1 atm. The internal temperature rises from 139 °C to 210 °C within 2 hours, and 0.026 g of tetraisopropyl orthotitanate (0.005 wt%) is added at an internal temperature of 150 °C. The clear reaction mixture is then refluxed at 210 °C for 7.5 hours, continuously distilling off a total of 39.6 g of water. Xylene and excess alcohol are distilled off under reduced pressure (T 内部 = 200°C, 8 mbar). The product (415 g) is obtained as a pale yellow oil.

[0071] Example 1-C: A mixture of 140 g of biobased hemimellitic acid, 375.1 g of Nafol 810D, and 40 mL of xylene in a 1 L three-neck flask coupled with a water separator is refluxed at 1 atm. The internal temperature rises from 130°C to 215°C within 5 hours. The clear reaction mixture is then refluxed at 215°C for 2 hours and then at 220°C for 6 hours. A total of 35.4 g of water is continuously distilled off. Xylene and excess alcohol are distilled off under reduced pressure (T 内部 = 210°C, 8 mbar). The product (388 g) is obtained as a pale yellow oil.

[0072] The kinematic viscosity of hemimellitic acid ester 1-B was measured as a function of temperature and compared with that of commercially available trimellitic acid ester 1' esterified with the same alcohol mixture. The shear rate was 1°C / s, and the temperature profile was 20 to -40°C, 0.2°C / min. The results of the rheological test are shown in Figure 1. Similar to trimellitic acid ester 1', hemimellitic acid ester 1 was found to have a relatively good kinematic viscosity at low temperatures.

[0073] Example 2: Determination of basic data for hemimellitic ester 1 compared to trimellitic ester 1' The basic data of hemimellitic acid ester 1 was measured and compared with that of commercial trimellitic acid ester 1' esterified with the same alcohol mixture. The results are shown in the table below.

[0074] [Table 1]

[0075] Example 3 to Example 5 Preparation of further hemimellitic acid esters and comparison esters (4') Example 3: A mixture of 140 g of biobased hemimellitic acid, 213 g of 1-octanol, 142 g of 1-dodecanol, and 40 mL of xylene in a 1 L three-neck flask equipped with a water separator is refluxed at 1 atm. The internal temperature rises from 125 to 210 °C within 2 hours, and 0.025 g of tetraisopropyl orthotitanate (0.005 wt%) is added at an internal temperature of 145 °C. The clear reaction mixture is then refluxed at 210 °C for 4 hours and then at 215 °C for an additional 3.5 hours. A total of 37.7 g of water is continuously distilled off. Xylene and excess alcohol are distilled off under reduced pressure (T 内部 = 210°C, 10 mbar). The product (397.7 g) is obtained as a pale yellow oil.

[0076] Example 4: In a 1 L three-neck flask equipped with a water separator, a mixture of 129.9 g of biobased hemimellitic acid, 91.5 g of 1-nonanol, 165.5 g of 1-undecanol, 81 g of Exxal 9 (ExxonMobil), 14.1 g of Exxal 10 (ExxonMobil), and 50 mL of xylene is refluxed at 1 atm. The internal temperature rises from 124 °C to 200 °C within 2 hours, and 0.5 g of tetraisopropyl orthotitanate (0.1 wt%) is added at an internal temperature of 160 °C. The clear reaction mixture is then refluxed at 200 °C for 2.5 hours, continuously distilling off a total of 34.8 g of water. Xylene and excess alcohol are then distilled off under reduced pressure (T 内部 = 195°C, 13 mbar). After removing the catalyst, the product (377 g) is obtained as a pale yellow oil.

[0077] Example 4'( TMA ester 4', a reference sample for Example 4 ): A mixture of 90 g of petrochemical-based trimellitic acid, 63.5 g of 1-nonanol, 114.7 g of 1-undecanol, 56.1 g of Exxal 9 (ExxonMobil), 9.76 g of Exxal 10 (ExxonMobil), and 35 mL of xylene is refluxed at 1 atm in a 1 L three-neck flask equipped with a water separator. At an internal temperature of 145°C, 0.35 g of tetraisopropyl orthotitanate (0.1 wt%) is added. Within 2 hours, the internal temperature rises from 159°C to 195°C. The clear reaction mixture is then refluxed at 195°C for 4 hours, continuously distilling off a total of 25.0 g of water. Xylene and excess alcohol are distilled off under reduced pressure (T 内部 = 200°C, 19 mbar). After removing the catalyst, the product (295 g) is obtained as a pale yellow oil.

[0078] Example 5: A mixture of 150 g of biobased hemimellitic acid, 353.2 g of 2-ethylhexan-1-ol, and 40 mL of xylene in a 1 L three-neck flask equipped with a water separator is refluxed at 1 atm. The internal temperature rises from 124 to 210 °C within 8 hours, and 0.025 g of tetraisopropyl orthotitanate (0.005 wt%) is added at an internal temperature of 145 °C. The clear reaction mixture is then refluxed at 210 °C for 5.5 hours. A total of 39.1 g of water is continuously distilled off. Xylene and excess alcohol are distilled off under reduced pressure (T 内部 = 205°C, 16 mbar). The product (404.4 g) is obtained as a pale yellow oil.

[0079] Three types of hemimellitic acid esters were produced by esterification of hemimellitic acid with various alcohols. The alcohols used and the basic data obtained are shown in Table 6, in comparison with the corresponding trimellitic acid esters.

[0080] [Table 2]

[0081] [Table 3]

[0082] Example 6: Preparation of various lubricant compositions Two lubricant compositions are prepared having the compositions set out in Table 1: [Table 4]

[0083] Basic data of the lubricant composition are shown in Table 2.

[0084] [Table 5]

[0085] Lubricant composition 2 according to the invention, based on hemimellitic esters, was found to exhibit similar baseline data to comparative composition 1, based on trimellitic esters, where the observed viscosity differences can be explained by the different initial viscosities of the base oils used.

[0086] Example 7: Determination of the oxidation stability of the lubricant composition of Example 6 The oxidation stability and evaporation loss of the lubricant composition of Example 6 are determined using dynamic differential calorimetry according to DIN 51007 (2019.04) and thermogravimetric analysis according to DIN 51006 (2005.07). The results are shown in Table 3.

[0087] [Table 6]

[0088] Lubricant composition 2 according to the present invention, which is based on hemimellitic ester, was found to exhibit high oxidation stability comparable to comparative composition 1, which is based on trimellitic ester.

[0089] Example 8: Thermal durability test The lubricant composition of Example 6 is investigated with respect to evaporation behavior and increase in apparent kinematic viscosity under temperature load.

[0090] For this purpose, comparative measurements are made of the change in evaporation behavior and apparent kinematic viscosity (mPas) as a measure of the progress of oxidation under thermal load. The sample amount per test is 5 g (±0.1 g). The samples are stored in aluminum dishes at 230 °C in a convection oven for 72 hours and then compared with each other.

[0091] Furthermore, the behavior of the residue after complete evaporation is measured by the Eisenmann test (250 °C / 72 h). For this, 5 g of the test sample is weighed onto a suitably bent and solvent-cleaned steel sheet, which is then evaporated in a convection drying cabinet at 250 °C for at least 72 hours. The square sheet is bent by hand on all four sides to form a bowl. After cooling, the reweighing result is recorded. The key to this test is to determine the solubility of the residue in fresh oil and the amount of residue formed. To do this, a drop of fresh oil is placed on the residue and gently rubbed in a circular motion with a rounded glass rod.

[0092] The results are shown in Table 4.

[0093] [Table 7]

[0094] All lubricant compositions were found to perform very well. Here, the evaporation behavior of the inventive lubricant composition 2 based on hemimellitic esters was as good as or better than that of the comparative composition 1 based on trimellitic esters, and it also showed a smaller increase in kinematic viscosity after 72 hours at 230°C. Furthermore, the inventive lubricant compositions formed less residue. Any residues were very soluble in fresh oil.

[0095] Example 9: Measurement of friction and wear of the lubricant composition of Example 6 The friction and wear of the lubricant composition of Example 6 is measured using a vibration friction and wear test (SRV). The SRV allows the coefficient of friction to be determined. The SRV is standardized in DIN 51 834.

[0096] The lubricant composition to be tested is subjected to a temperature step test (50 to 250°C) for 165 minutes at a load of 250N and 50Hz in accordance with DIN 51 834. In this test, a steel ball vibrates against a steel plate fixed to the front. This allows the effectiveness, durability, and lifespan of the lubricant composition to be investigated in the vibratory motion under mixed friction conditions.

[0097] The test results are shown in Figure 2.

[0098] It was found that the lubricant composition according to the invention based on hemimellitic esters exhibited friction values ​​as good as comparative composition 1 based on trimellitic esters.

[0099] Example 10: Preparation and testing of grease formulation 3 based on hemimellitic acid esters and comparative grease formulation 4 based on trimellitic acid esters Grease formulation 3 according to the present invention based on hemimellitic ester and comparative grease formulation 4 based on trimellitic ester are formulated to the compositions shown in the table below.

[0100] [Table 8]

[0101] As the hemimellitic ester, Example 4, Table 6a is used, and as the trimellitic ester, TMA ester 4', Table 6a is used.

[0102] The basic data for Grease Formulation 3 and Comparative Grease Formulation 4 are shown in the table below.

[0103] [Table 9-1] [Table 9-2]

[0104] Both Grease Formulation 3 and Comparative Grease Formulation 4 exhibit equally good miscibility and shear stability. Water resistance, oil separation, noise ratio, and water content are at similar levels for all formulations.

[0105] Example 11: High temperature properties of grease formulation 3 and comparative grease formulation 4 The high temperature properties of Grease Formulation 3 and Comparative Grease Formulation 4 are investigated. The results are shown in the table below.

[0106] [Table 10]

[0107] At higher temperatures, both formulations were found to have a dropping point of approximately 300°C. In copper corrosion tests at 150°C and 160°C, both formulations performed equally well. Furthermore, in the FE9 test, both samples showed very good thermal stability.

[0108] Example 11: Preparation and testing of grease formulation 5 based on hemimellitic acid esters and comparative grease formulation 6 based on trimellitic acid esters Grease formulation 5 according to the present invention based on hemimellitic ester and comparative grease formulation 6 based on trimellitic ester are formulated to the compositions shown in the table below.

[0109] [Table 11]

[0110] For the preparation of Hemimellitate Ester Example 6, the following alcohol mixture is used as the alcohol: 25% by weight n-octanol 40% by weight 2EH-ol 35% by weight n-decanol.

[0111] [Table 12-1] Table 12-2

Claims

1. The following general formula I 【Chemistry 1】 [In the formula, R １ , R ２ and R ３ are independent of each other, a) unsubstituted branched or unbranched C １ ~C ２０ an alkyl group, or b) a C having at least one substituent selected from the group consisting of a cycloalkyl group and an aromatic group; １ ~C ５ an alkyl group, or c) C6 to C ２０ Aromatic group or C ５ ~C ２０ cycloalkyl group as a base oil in a lubricant composition for the lubrication of tribological systems, in which the hemimellitic ester of formula I is present as a mixture of various compounds of formula I and / or the hemimellitic ester of formula I contains at least partially mutually different groups R １ , R ２ and R ３ To have, to use.

2. 2. The use according to claim 1, characterized in that the hemimellitic acid ester of formula I is at least partially biobased.

3. 3. Use according to claim 1 or 2, characterized in that the lubricant composition comprises at least 10 wt. % bio-based carbon, based on the total weight of organic carbon in the lubricant composition.

4. 3. The use according to claim 1 or 2, characterized in that the hemimellitic ester of formula I comprises at least 30 wt. % bio-based carbon, based on the total weight of the hemimellitic ester of formula I in the lubricant composition.

5. 3. The use according to claim 1 or 2, characterized in that the acid component of the hemimellitic ester of formula I comprises at least 30 wt. % bio-based carbon, based on the total weight of the acid component of the hemimellitic ester of formula I in the lubricant composition.

6. At least one group R １ , R ２ and / or R ３ is unsubstituted branched or unbranched C ５ ~C ２０ 3. The use according to claim 1 or 2, wherein the alkyl group is an alkyl group.

7. At least one group R １ , R ２ and / or R ３ But C １ ~C ３ an alkyl group, wherein the alkyl group is C ５ ~C １５ Cycloalkyl groups and C6-C １５ 3. Use according to claim 1 or 2, characterized in that it has at least one substituent selected from the group consisting of aromatic groups.

8. At least one group R １ , R ２ and / or R ３ But there is at least one C ５ ~C １５ substituted with a cycloalkyl group or C6-C １５ 3. Use according to claim 1 or 2, characterized in that the aromatic group is a methyl, ethyl or propyl group substituted with an aromatic group.

9. At least one group R １ , R ２ and / or R ３ 3. Use according to claim 1 or 2, characterized in that is selected from the group consisting of octanyl, ethylhexanyl, nonanyl, decanyl, undecanyl, dodecanyl, isotridecyl, tricyclodecanemethyl, furfuryl.

10. The group R １ , R ２ and R ３ 3. Use according to claim 1 or 2, characterized in that, independently of one another, they contain no atoms other than carbon and hydrogen.

11. 3. Use according to claim 1 or 2, characterized in that the lubricant composition comprises the hemimellitic ester of formula I in an amount of 20% to 90% by weight, relative to the total weight of the lubricant composition.

12. The hemimellitic acid ester of formula I is soluble in water at 40° C. for 30 mm ２ / s~150mm ２ 3. Use according to claim 1 or 2, characterized in that it has a kinematic viscosity in the range of 1 / s.

13. 3. Use according to claim 1 or 2, characterized in that the lubricant composition comprises 5 to 50% by weight of polyisobutylene, based on the total weight of the lubricant composition.

14. the lubricant composition is present as an oil formulation and comprises at least one further base oil in a proportion of 10% to 50% by weight, relative to the total weight of the lubricant composition; or The lubricant composition is present as a grease formulation and comprises at least one further base oil in a proportion of 10% to 50% by weight, relative to the total weight of the lubricant composition.

3. Use according to claim 1 or 2, characterized in that

15. 15. Use according to claim 14, characterized in that the further base oil is selected from esters and triglycerides and / or estolides, poly-alpha-olefins, polyethers and / or mineral oils.

16. Use according to claim 15, characterized in that the further base oil is selected from esters of aromatic and / or aliphatic di-, tri- or tetracarboxylic acids with one or a mixture of C7 to C22 alcohols, esters of trimethylolpropane, pentaerythritol or dipentaerythritol with aliphatic C7 to C22 carboxylic acids, esters of C18 dimer acids with C7 to C22 alcohols, complex esters, either as single components or in any mixture.

17. below: from 20% to 90% by weight of a compound of general formula I below as base oil 【Chemistry 2】 [In the formula, R １ , R ２ and R ３ are independent of each other, a) unsubstituted branched or unbranched C １ ~C ２０ an alkyl group, or b) a C having at least one substituent selected from the group consisting of a cycloalkyl group and an aromatic group; １ ~C ５ an alkyl group, or c) C6 to C ２０ Aromatic group or C ５ ~C ２０ cycloalkyl group wherein the hemimellitic ester of formula I is present as a mixture of various compounds of formula I and / or the hemimellitic ester of formula I is at least partially composed of groups R １ , R ２ and R ３ Hemimellitic acid ester having the formula - 5% to 50% by weight of polyisobutylene, - 0.1% to 8% by weight of additives 1. A lubricant composition formed as an oil formulation comprising:

18. below: from 20% to 90% by weight of a compound of general formula I below as base oil 【Transformation 3】 [In the formula, R １ , R ２ and R ３ are independent of each other, a) unsubstituted branched or unbranched C １ ~C ２０ an alkyl group, or b) a C having at least one substituent selected from the group consisting of a cycloalkyl group and an aromatic group; １ ~C ５ an alkyl group, or c) C6 to C ２０ Aromatic group or C ５ ~C ２０ cycloalkyl group wherein the hemimellitic ester of formula I is present as a mixture of various compounds of formula I and / or the hemimellitic ester of formula I is at least partially composed of groups R １ , R ２ and R ３ Hemimellitic acid ester having the formula - 3 to 30% by weight of a thickener, - 0.1 to 8% by weight of additives 1. A lubricant composition formed as a grease formulation comprising:

19. below: from 20% to 70% by weight of a compound of general formula I below as base oil 【Chemistry 4】 [In the formula, R １ , R ２ and R ３ are independent of each other, a) unsubstituted branched or unbranched C １ ~C ２０ an alkyl group, or b) a C having at least one substituent selected from the group consisting of a cycloalkyl group and an aromatic group; １ ~C ５ an alkyl group, or c) C6 to C ２０ Aromatic group or C ５ ~C ２０ cycloalkyl group wherein the hemimellitic ester of formula I is present as a mixture of various compounds of formula I and / or the hemimellitic ester of formula I is at least partially composed of groups R １ , R ２ and R ３ Hemimellitic acid ester having the formula - 3 to 30% by weight of a thickener, - 10% to 50% by weight of at least one further base oil, 0.1 to 8% by weight of additives 1. A lubricant composition formed as a grease formulation comprising:

20. 20. The lubricant composition of claim 18 or 19, wherein the lubricant composition formed into a grease formulation comprises 10% to 40% by weight of polyisobutylene.

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