WO2023016908A1 - Use of hemimellitic ester as a base oil for lubricant compositions - Google Patents

Abstract

The invention relates to the use of hemimellitic ester of the following general formula I, wherein R₁, R₂ and R₃ are independently of one another a) an unsubstituted, branched or unbranched C1 to C20 alkyl group or b) a C1 to C5 alkyl group containing at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups or C) a C5 to C20 aromatic group or a C5 to C20 cycloalkyl group, wherein the hemimellitic ester of formula I may be in the form of a mixture of different compounds of formula I, as a base oil of a lubricant composition for lubricating tribological systems.

Description

USE OF HEMIMELLITE ESTER AS A BASE OIL FOR LUBRICANT COMPOSITIONS

Description

The invention relates to the use of hemimellitic ester as base oil for lubricant compositions, and also to lubricant compositions based on hemimellitic ester as base oil.

Lubricants are essential components of many industrial processes where two or more surfaces move in close contact. The range of applications for lubricating oils is very wide, including automotive lubricants, two-stroke and four-stroke petrol engine lubricants, diesel engine lubricants, gas engine oils, gas turbine oils, automatic transmission fluids, gear oils, etc.

Lubricants can be embodied as lubricating oils and lubricating greases. Industrial lubricating oils include but are not limited to industrial gear oils, pneumatic tool lubricants, high temperature oils, air and gas compressor oils for all types of compressors, machine tool oils, textile oils, steam turbine oils, hydraulic fluids, paper machine oils, food machine oils, steam cylinder oils, metalworking fluids for metal cutting, metal rolling, metal drawing, metal forging and metal stamping. In addition to the lubricating oil, lubricating greases also include one or more thickeners. With regard to the sustainability of lubricants, it is desirable if they contain at least a proportion of bio-based base oils. In addition, it is advantageous in practice if a lubricant contains a base oil that can be obtained from both (at least in part) biological and petrochemical sources. As a result, a high level of flexibility in lubricant production can be combined with the option of providing an environmentally friendly, sustainable lubricant. However, many bio-based oils are not suitable for lubricant applications because they do not have the desired property profile, for example in terms of oxidation stability and low-temperature behavior.

The use of trimellitic acid ester as a base oil for lubricants is known and is used in practice. However, this ester is not currently produced on an industrial scale from biological raw materials.

wobei R eine lineare oder verzweigte Alkylgruppe mit einer Kettenlänge von 8 bis 16 Kohlenstoffatomen ist und 5 bis 50 Gew.% eines hydrierten Polyisobutylens, eines vollhydrierten Polyisobutylens oder einer Mischung aus einem vollhydrierten und einem hydrierten Polyisobutylen. Das beschriebene Zweikomponentensystem weist eine sehr gute Leistungsfähigkeit im Hinblick auf die thermische Stabilität und die Rückstandsbildung bzw. das Rückstandsverhalten auf. Allerdings wird dieser Ester derzeit nicht großtechnisch aus biologischen Rohstoffen gewonnen. WO2012159738 A1 discloses a high-temperature oil for lubricating chains, chain rollers and belts of continuous presses, comprising 40 to 91.9% by weight of a compound of the general formula (II)

where R is a linear or branched alkyl group having a chain length of 8 to 16 carbon atoms and 5 to 50% by weight of a hydrogenated polyisobutylene, a fully hydrogenated polyisobutylene or a mixture of a fully hydrogenated and a hydrogenated polyisobutylene. The two-component system described has very good performance with regard to thermal stability and residue formation or residue behavior. However, this ester is not currently produced on an industrial scale from biological raw materials.

The object of the present invention is to provide a base oil for a lubricant composition that consists of both biological as well as from petrochemical sources. Furthermore, the resulting lubricant composition should have good oxidation stability, lubricating action and good low-temperature behavior. In addition, it should have a good lubricating effect over a long period of time even at a constantly high temperature. Furthermore, the lubricant composition should be able to be provided in different viscosities, depending on the desired application.

wobei Ri , R2 und R3 unabhängig voneinander a) eine unsubstituierte, verzweigte oder unverzweigte C1- bis C20- Alkylgruppe sind oder b) eine C1- bis C5-Alkylgruppe sind, die mindestens einen Substituenten, ausgewählt aus der Gruppe bestehend aus Cycloalkylgruppen und aromatischen Gruppen aufweist, oder c) eine C5- bis C20 aromatische Gruppe oder eine C5- bis C20- Cycloalkylgruppe sind, wobei der Hemimellitsäureester als Gemisch verschiedener Verbindungen der Formel I vorliegen kann, als Basisöl einer Schmierstoffzusammensetzung zum Schmieren von tribologischen Systemen gelöst. This object is achieved according to the invention through the use of hemimellitic acid ester of the following general formula I

where Ri , R2 and R3 are independently a) an unsubstituted, branched or unbranched C1 to C20 alkyl group or b) a C1 to C5 alkyl group having at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups has, or c) are a C5 to C20 aromatic group or a C5 to C20 cycloalkyl group, where the hemimellitic acid ester can be present as a mixture of different compounds of the formula I, dissolved as the base oil of a lubricant composition for lubricating tribological systems.

Surprisingly, it was found that the use of hemimellitic acid ester of the above formula I as a base oil makes it possible to obtain a lubricant composition with good oxidation stability, lubricating action and good low-temperature behavior. In addition, it also shows at a constantly high temperature over a long period of time Period good lubricating properties. Furthermore, the lubricant composition can be provided in different viscosities, depending on the desired application. This was surprising because hemimellitic acid ester can be obtained from biological sources and bio-based lubricants, as explained above, usually do not have the desired range of properties in terms of oxidation stability, lubricating effect and low-temperature behavior.

The production of hemimellitic acid ester starting from biomass is known and is described, for example, in US10562875B2. Depending on the raw materials used, the hemimellitic acid ester obtained can contain a high proportion of bio-based carbon or be completely bio-based. However, hemimellitic acid ester can also be easily obtained from petroleum or petrochemical sources, which increases flexibility in lubricant production.

In a preferred embodiment, the hemimellitic acid ester is at least partially bio-based. By this is meant that the hemimellitic acid ester is made, at least in part, from raw materials derived from biological sources and/or renewable agricultural materials (including plant, animal, and man-made materials) and not from petroleum or petrochemical sources. Examples of biological sources are agriculture, forestry, plant breeding or animal raw materials. Preferred biological sources are straw, animal waste products, agricultural and forestry waste.

In the lubricant composition, hemimellitic acid ester can be present as the only base oil or in a mixture with other base oils.

A tribological system is understood to be a technical construction whose function is realized by mechanically moving structural elements that are subject to friction and wear. Tribological systems have the task of movements, energy and material transform, transport and make technically usable. Preferred tribological systems are tribological systems that have metallic and/or non-metallic materials, such as roller and plain bearings, in particular roller and plain bearings in automotive engineering, conveyor technology, mechanical engineering and/or office technology, gears, chains, sliding guides and Joints, in particular wheel bearings in motor vehicles, bearings in wind turbines, in particular rotor bearings, in wind turbines and/or rotating plain bearings, for example fan bearings, or linearly guided plain bearings and/or ball joints, especially ball joints for use in the automotive sector. Possible tribological systems also include sliding partners in industrial plants and machines, but also in the areas of household machines, entertainment electronics, especially in oil-lubricated systems, lubrication of chains, chain rollers and steel belts of continuous wood presses.

In a preferred embodiment, the tribological systems have surfaces that contain metallic and/or non-metallic materials, preferably composite materials, aluminum, aluminum alloys, steel, stainless steel and cast materials, non-ferrous metals, plastics, fiber-reinforced plastics and/or polymers.

In a preferred embodiment of the invention, the lubricant composition has at least 10% by weight, for example from 10 to 100% by weight and/or 10 to 95% by weight, preferably at least 15% by weight, for example from 15% by weight to 95% by weight. %, in particular at least 20% by weight, for example from 20% by weight to 95% by weight, of bio-based carbon based on the total weight of organic carbon in the lubricant composition. The content of bio-based carbon can be determined using the ASTM International Radioisotope Standard Method D 6866. The latest version of the standard on the filing date applies. This method determines the bio-based content of a material based on the amount of bio-based carbon in the material as a percentage of the weight of the total organic carbon in the material under study. The method is based on the fact that bio-based products have carbon isotope ratios of 13C/12C and 14C/12C, which are different from those found in petroleum-derived materials.

In a further preferred embodiment of the invention, the hemimellitic acid ester of the formula I has at least 30% by weight, for example from 30 to 100% by weight, preferably at least 40% by weight, for example from 40% by weight to 100% by weight, in particular at least 50 % by weight, for example from 50% by weight to 100% by weight of bio-based carbon, based on the total weight of the hemimellitic acid ester of the formula I, in the lubricant composition, in each case measured using the ASTM International Radioisotope Standard Method D 6866. The latest on the filing date applies version of the standard.

In a further preferred embodiment of the invention, the acid component of the hemimellitic acid ester of the formula I has at least 30% by weight, for example from 30 to 100% by weight, preferably at least 40% by weight, for example from 40% by weight to 100% by weight, in particular at least 50% by weight, for example from 50% by weight to 100% by weight, bio-based carbon based on the total weight of the acid component of the hemimellitic acid ester of the formula I in the lubricant composition, in each case measured using the ASTM International Radioisotope Standard Method D 6866. The applies latest version of the standard on the filing date.

In a preferred embodiment of the invention, at least one radical Ri, R2 and/or R3 is an unsubstituted, branched or unbranched C1 to C20 alkyl group, more preferably a C5 to C20 alkyl group, more preferably a C6 to C18 alkyl group, and in particular a C8 to C18 alkyl group. In a further particularly preferred embodiment of the invention, at least one R 1 , R 2 and/or R 3 radical is selected from the group consisting of octanyl, ethylhexanyl, nonanyl, decanyl, undecanyl and dodecanyl.

In a further particularly preferred embodiment of the invention, at least one R 1 , R 2 and/or R 3 radical is selected from the group consisting of octanyl, 2-ethylhexan-1-yl, 1-nonanyl, decanyl, 1-undecanyl, 1-dodecanyl.

In a further preferred embodiment of the invention, at least one radical Ri, R2 and/or Rs is a C1 - to C5-alkyl group, preferably a C1 - to C3-alkyl group, more preferably a C1 - to C2-alkyl group, and in particular a C1 - Alkyl group each having at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups. In this embodiment, the number of carbon atoms in the alkyl group mentioned does not include the number of carbon atoms in the substituents. According to the invention, cycloalkyl groups include both monocyclic and polycyclic compounds.

Preferably, the substituents independently have from 5 to 19 carbon atoms, more preferably from 5 to 17 carbon atoms, and most preferably from 5 to 15 carbon atoms. More preferably, the substituents are independently selected from C5 to C19 cycloalkyl groups, or C5 to C19 aromatic groups, more preferably from C5 to C17 cycloalkyl groups or C5 to C17 aromatic groups, and especially from C5 to C15 cycloalkyl groups or C5 to C15 aromatic groups.

In a further preferred embodiment of the invention, at least one radical Ri, R2 and/or Rs is a methyl group, ethyl group or a propyl group which is substituted with at least one cycloalkyl group having 5 to 15 carbon atoms or with at least one aromatic group having 5 to 15 carbon atoms, in particular 5 is substituted with up to 10 carbon atoms. Ri, F and R3 are particularly preferably independently a methyl group which is substituted with at least one cycloalkyl group having 5 to 15 carbon atoms or with at least one aromatic group having 5 to 15 carbon atoms, in particular 5 to 10 carbon atoms.

In a further embodiment of the invention, at least one radical Ri, R2 and/or Rs is a C5 to C20 aromatic group or a C5 to C20 cycloalkyl group. At least one R 1 , R 2 and/or R 3 radical is preferably selected from phenyl, cyclopentyl, cyclohexyl, naphthyl, isotridecyl, tricyclodecanemethyl and furfuryl.

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

In a further particularly preferred embodiment of the invention, at least one radical Ri, R2 and/or R3, preferably at least two radicals Ri, R2 and/or R3, and in particular all radicals Ri, 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.

The radicals Ri, R2 and R3 can be the same or different.

In a further preferred embodiment, the hemimellitic ester of the formula I has R 1 , R 2 and R 3 radicals which are at least partly different from one another. The hemimellitic acid ester of the formula I is also preferably a mixture of different compounds of the formula I.

Also preferably, the radicals R1, R2 and R3 independently of one another have no atoms other than carbon and hydrogen. In a preferred embodiment of the invention, the lubricant composition contains the hemimellitic acid ester of the formula I in an amount of from 20% to 90% by weight, more preferably from 25% to 70% by weight, even more preferably from 25% to 60% by weight % by weight and in particular from 30% by weight to 50% by weight, in each case based on the total weight of the lubricant composition.

In a further preferred embodiment of the invention, the hemimellitic ester of the formula I has a kinematic viscosity at 40° C. [mm ² /sec] in the range from 30 mm ² /s to 150 mm ² /s, preferably from 30 mm ² /s to 100 mm ² /s, more preferably from 50 mm ² /s to 150 mm ² /s and in particular 50 mm ² /s to 90 mm ² /s.

In a further preferred embodiment of the invention, the lubricant composition is present as an oil formulation and has a kinematic viscosity at 40° C. [mmVsec] in the range from 100 mm ² /s to 460 mm ² /s, preferably from 150 mm ² /s to 320 mm ² /s up.

In a further preferred embodiment of the invention, the lubricant composition is present as a grease formulation and the hemimellitic ester of the formula I and/or a mixture of hemimellitic ester of the formula I and other base oils has a kinematic viscosity at 40° C. [mmVsec] in the range of 80 mm ² / s to 460 mm ² /s, preferably from 100 mm ² /s to 320 mm ² /s.

In a further preferred embodiment of the invention, the lubricant composition contains 5 to 50% by weight, more preferably from 15 to 35% by weight and in particular from 15 to 30% by weight, polyisobutylene, based in each case on the total weight of the lubricant composition. The advantage of using polyisobutylene is that it can be used to adjust the viscosity of the lubricant composition in a particularly simple manner. In addition, in combination with the hemimellitic acid ester Formula I a particularly good residue behavior can be achieved after complete evaporation. According to a preferred embodiment, the polyisobutylene has a number-average molecular weight of 115 to 15,000 g/mol, preferably 160 to 5,000 g/mol, measured according to DIN 55672-1:2016-03 (gel permeation chromatography (GPC) - part 1: tetrahydrofuran (THF ) as eluent).

As already explained above, the lubricant composition can be present both as a fat formulation and as an oil formulation.

When the lubricating composition is in the form of a grease formulation, it contains a thickening agent. Consequently, in a preferred embodiment of the invention, the lubricant composition contains from 3 to 30% by weight of thickener.

The thickening agent is preferably a reaction product of a diisocyanate, preferably 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 individually or in combination, with an amine of the general formula R'2-N-R, or a diamine of the general formula Formula R'2-N-R-NR'2 where R is aryl, alkyl or alkylene having from 2 to 22 carbon atoms and R' is identical or different hydrogen, alkyl, alkylene or aryl, or with mixtures of amines and diamines.

In a further preferred embodiment, the thickener is selected from Al complex soaps, metal simple soaps of the elements of the first and second main group of the periodic table, metal complex soaps of the elements of the first and second main group of the periodic table, bentonites, sulfonates, silicates, aerosil, polyimides or PTFE or a mixture of the aforementioned thickeners. In addition to the hemimellitic acid ester of the formula I, the lubricant composition can also contain at least one other base oil.

If the lubricant composition is in the form of an oil formulation and contains at least one additional base oil, the proportion of the additional base oil is preferably from 10% by weight to 50% by weight, more preferably from 10% by weight to 40% by weight, more preferably from 20% by weight .% to 40% by weight and in particular from 25% by weight to 40% by weight, based in each case on the total weight of the lubricant composition.

If the lubricant composition is in the form of a grease formulation and contains at least one additional base oil, the proportion of the additional base oil is preferably from 10% by weight to 50% by weight, more preferably from 25% by weight to 50% by weight and in particular from 30% by weight. % to 50% by weight, based in each case on the total weight of the lubricant composition.

If the lubricant composition contains at least one other base oil, the lubricant composition preferably contains the hemimellitic acid ester of the formula I in an amount of from 20% by weight to 70% by weight, more preferably from 25% by weight to 70% by weight, even more preferably from 25% by weight .% to 60% by weight and in particular from 30% by weight to 50% by weight, based in each case on the total weight of the lubricant composition.

Other suitable base oils are customary lubricating oils that are liquid at room temperature (20° C.). The further base oil preferably has a kinematic viscosity of 18 mm ² /s to 20000 mm ² /s, in particular 30 mm ² /s to 400 mm ² /s at 40°C. With base oils, a distinction is made between mineral and synthetic oils. By base oil are meant the usual base fluids used in the manufacture of lubricants, particularly oils belonging to Groups I, II, II+, III, IV or V according to the American Petroleum Institute (API) classification [NLGI Spokesman, N. Samman, Volume 70, Number 11, p.14ff] can be assigned to understand. Mineral oils are after classified by the API Group. API Group I are mineral oils that z. B. consist of naphthenic or paraffinic oils. If these mineral oils are chemically modified compared to API Group I oils, low in aromatics, low in sulfur and have a low proportion of saturated compounds and thus an improved viscosity/temperature behavior, the oils are classified according to API Groups II and III. API Group III also includes so-called gas-to-liquid oils, which are not produced from the refining of crude oil, but through the chemical conversion of natural gas. Furthermore, reraffinates can also be used.

Synthetic oils which may be mentioned are polyethers, esters, polyesters, preferably polyalphaolefins, in particular metallocene polyalphaolefins, perfluoropolyalkyl ethers (PFPAE), alkylated naphthalenes, silicone oils and alkylaromatics and mixtures thereof. The polyether compound can have free hydroxyl groups, but can also be fully etherified or end groups esterified and/or made from a starting compound with one or more hydroxyl and/or carboxyl groups (-COOH). Polyphenyl ethers, optionally alkylated, are also possible as sole components or, even better, as mixed components.

Esters of an aromatic and/or aliphatic di-, tri- or tetracarboxylic acid 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, as individual components or in any mixture. Also preferred esters are triglycerides and/or estolides.

Silicone oils, native oils and derivatives of native oils are also suitable.

Further base oils which are particularly preferred according to the invention are esters, in particular esters of an aromatic and/or aliphatic di-, tri- or tetracarboxylic acid 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, as individual components or in any mixture, as well as triglycerides and/or estolides, polyalphaolefins, polyethers and /or mineral oils.

Furthermore, the lubricant composition can contain inorganic or organic solid lubricants, preferably in a proportion of 0.1% by weight to 5% by weight, preferably 0.1% by weight to 3% by weight, based on the total weight of the lubricant composition. Solid lubricants are preferably 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, Nano-Tubes, SiO2 modifications or a mixture thereof.

More preferably, the lubricant composition contains 0.1 to 8% by weight of additives selected from the group consisting of anti-corrosion additives, antioxidants, anti-wear additives, metal deactivators, ion complexing agents and/or UV stabilizers.

According to the invention, particularly suitable antioxidants are the following compounds: styrenated diphenylamines, diaromatic amines, phenolic resins, thiophenolic resins, phosphites, butylated hydroxytoluene, butylated hydroxyanisole, phenyl-alpha-naphthylamine, phenyl-beta-naphthylamine, octylated/butylated diphenylamine, di-alpha-tocopherol , di-tert-butyl-phenyl, benzenepropanoic acid, sulphur-containing phenolic compounds and mixtures of these components.

Also 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 amines Antioxidants such as alkylated phenyl-alpha-naphthylamine, dialkyldiphenylamine, sterically hindered phenols such as butylated hydroxytoluene (BHT), phenolic antioxidants with thioether groups, Zn- or Mo- or W-dialkyldithiophosphates and phosphites.

Preferred anti-corrosion additives, 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, mixture of phosphoric acid and mono- and diisooctyl ester reacted with (C11-14)-alkylamines, mixture of phosphoric acid and mono- and diisooctyl ester reacted with tert-alkylamine and primary ( C12-14) amines, dodecanoic acid, triphenyl phosphorothioate and amine phosphates and mixtures thereof. Commercially available additives are the following: IRGAMET® 39, IRGACOR® DSS G, Amine O; SARKOSYL® O (Ciba), COBRATEC® 122, CUVAN® 303, VANLUBE® 9123, CI-426, CI-426EP, CI-429 and CI-498.

Anti-wear additives preferred according to the invention are amines, amine phosphates, phosphates, thiophosphates, phosphorothioates and mixtures of these components. Preferred anti-wear additives are selected from the group consisting of anti-wear additives based on diphenyl cresyl phosphate, amine neutralized phosphates, alkylated and non-alkylated triaryl phosphates, alkylated and non-alkylated triaryl thiophosphates, zinc or Mo or W dialkyl dithiophosphates, carbamates, thiocarbamates, zinc or mo or W-dithiocarbamates, dimercapto-thiadiazole, calcium sulfonates 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. Another object of the invention is a lubricant composition designed as an oil formulation comprising:

wobei Ri , F und R3 unabhängig voneinander a) eine verzweigte oder unverzweigte C1 - bis C20-Alkylgruppe sind oder b) eine C1- bis C5-Alkylgruppe sind, die mindestens einen Substituenten, ausgewählt aus der Gruppe bestehend aus Cycloalkylgruppen und aromatischen Gruppen, aufweist, oder c) eine C5- bis C20 aromatische Gruppe oder eine C5- bis C20- Cycloalkylgruppe sind, wobei der Hemimellitsäureester der Formel I als Gemisch verschiedener20% by weight to 90% by weight, preferably 50% by weight to 85% by weight, of hemimellitic acid ester of the following general formula I

where Ri , F and R3 are independently a) a branched or unbranched C1 to C20 alkyl group or b) a C1 to C5 alkyl group having at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups , or c) a C5 to C20 aromatic group or a C5 to C20 cycloalkyl group, wherein the hemimellitic ester of the formula I as a mixture of different

Compounds of formula I may be present as a base oil,

5 wt% to 50 wt%, preferably 10 wt% to 50 wt% polyisobutylene,

0.1% to 8% by weight additives.

In a further preferred embodiment, the lubricant composition designed as an oil formulation additionally has 10% by weight to 45% by weight, preferably 30% by weight to 45% by weight, of at least one further base oil.

wobei Ri , R2 und R3 unabhängig voneinander a) eine verzweigte oder unverzweigte C1 - bis C20-Alkylgruppe sind oder b) eine C1- bis C5-Alkylgruppe sind, die mindestens einen Substituenten, ausgewählt aus der Gruppe bestehend aus Cycloalkylgruppen und aromatischen Gruppen, aufweist, oder c) eine C5- bis C20 aromatische Gruppe oder eine C5- bis C20- Cycloalkylgruppe sind, wobei der Hemimellitsäureester der Formel I als Gemisch verschiedenerAnother object of the invention is a lubricant composition designed as a grease formulation comprising: - 20% to 90% by weight, preferably 30% to 90% by weight, more preferably 40% to 90% by weight, of hemimellitic acid esters of the following general formula I

where Ri , R2 and R3 are independently a) a branched or unbranched C1 to C20 alkyl group or b) a C1 to C5 alkyl group having at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups , or c) a C5 to C20 aromatic group or a C5 to C20 cycloalkyl group, wherein the hemimellitic ester of the formula I as a mixture of different

Compounds of formula I may be present as a base oil,

3 to 30% by weight thickener,

0.1 to 8% by weight of additives.

Another object of the invention is a lubricant composition designed as a grease formulation comprising:

wobei Ri, R2 und R3 unabhängig voneinander d) eine verzweigte oder unverzweigte C1 - bis C20-Alkylgruppe sind oder e) eine C1- bis C5-Alkylgruppe sind, die mindestens einen Substituenten, ausgewählt aus der Gruppe bestehend aus Cycloalkylgruppen und aromatischen Gruppen, aufweist, oder f) eine C5- bis C20 aromatische Gruppe oder eine C5- bis C20- Cycloalkylgruppe sind, wobei der Hemimellitsäureester der Formel I als Gemisch verschiedener Verbindungen der Formel I vorliegen kann, als Basisöl, - 20% to 70% by weight, preferably 30% to 70% by weight, more preferably 40% to 70% by weight, of hemimellitic acid esters of the following general formula I

where Ri, R2 and R3 are independent of each other d) a branched or unbranched C1 to C20 alkyl group or e) a C1 to C5 alkyl group having at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups, or f) a C5 to C20 aromatic group or a C5 to C20 cycloalkyl group, where the hemimellitic acid ester of the formula I can be present as a mixture of different compounds of the formula I, as a base oil,

3 to 30% by weight thickener,

10% by weight to 50% by weight of at least one other base oil, 0.1 to 8% by weight of additives.

In a preferred embodiment, the lubricant composition designed as a grease formulation contains 10% by weight to 40% by weight of polyisobutylene.

In a further preferred embodiment, the lubricant composition designed as a grease formulation has 0.1% by weight to 5% by weight of inorganic or organic solid lubricants.

Preferred components of the lubricant compositions according to the invention are those mentioned in relation to the use according to the invention.

In particular, particularly preferred thickeners for the lubricant composition designed as a grease formulation are a reaction product of a diisocyanate, preferably 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 individually or in combination, with an amine of the general formula R'2-NR, or a diamine of the general formula R'2-NR-NR'2, where R is an aryl, alkyl or alkylene radical having from 2 to 22 carbon atoms and R' is identical or different a hydrogen, alkyl, alkylene or aryl radical, or with mixtures of amines and diamines.

In a further preferred embodiment, the thickener is selected from Al complex soaps, metal simple soaps of the elements of the first and second main group of the periodic table, metal complex soaps of the elements of the first and second main group of the periodic table, bentonites, sulfonates, silicates, aerosil, polyimides or PTFE or a mixture of the aforementioned thickeners.

Furthermore, particularly preferred other base oils for the lubricant compositions according to the invention designed as a grease formulation or as an oil formulation are esters, in particular esters of an aromatic and/or aliphatic di-, tri- or tetracarboxylic acid 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, as individual components or in any mixture, as well as triglycerides and/or estolides, polyalphaolefins, polyethers and/or mineral oils.

character description

1 shows the dynamic viscosity of hemimellitic acid ester of the formula I compared to trimellitic acid ester as a function of temperature.

FIG. 2 shows the average friction of several lubricant compositions containing hemimellitic acid esters of the formula I according to the invention compared to lubricant compositions containing trimellitic acid esters as a function of temperature, determined by means of SRV. measurement methods

Viscosity:

The viscosity measurement is carried out with DIN 51562 (2018) using a Stabinger viscometer SVM 3000 (Anton Paar).

Content of bio-based carbon:

The bio-based carbon content is determined using the ASTM International Radioisotope Standard Method D 6866 in the version valid on the filing date.

The invention is explained in more detail below with reference to examples that do not restrict the invention.

Example 1 Determination of the dynamic viscosity of hemimellitic ester of the formula I in comparison with trimellitic ester

The hemimellitic acid ester 1 is prepared via the following reaction:

Example 1-A:

A mixture of 150 g organic. Hemimellitic acid, 369.6 g Nafol 810D and 60 mL xylene in a 1 L three-necked flask combined with a water separator is refluxed at 1 atm. Within 4 hours the internal temperature rises from 126°C to 200°C and 0.52 g of tetraisopropyl orthotitanate (0.1% by weight) is added at an internal temperature of 160°C. Then the clear reaction mixture Refluxed at 200° C. for 2 h and a total of 38.8 g of water were continuously distilled off. The xylene and the excess alcohol are distilled off under reduced pressure (Tinn.=200° C., 10 mbar). After removing the catalyst, the product (407.7 g) is obtained as a light yellow oil.

Example 1 -B:

A mixture of 150 g organic. Hemimellitic acid, 369.6 g Nafol 810D and 45 mL xylene in a 1 L three-necked flask combined with a water separator is refluxed at 1 atm. Within 2 hours the internal temperature rises from 139°C to 210°C 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 h and a total of 39.6 g of water are continuously distilled off. The xylene and the excess alcohol are distilled off under reduced pressure (Tinn.=200° C., 8 mbar). The product (415 g) is obtained as a light yellow oil.

Example 1 -C:

A mixture of 140 g organic. Hemimellitic acid, 375.1 g Nafol 810D and 40 mL xylene in a 1 L three-necked flask combined 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 h and further at 220° C. for 6 h. A total of 35.4 g of water is continuously distilled off. The xylene and excess alcohol are distilled off under reduced pressure (Tinn.=210° C., 8 mbar). The product (388 g) is obtained as a light yellow oil.

The dynamic viscosity of hemimellitic ester 1-B is measured as a function of temperature and compared to the commercial trimellitic ester 1' esterified with the same alcohol mixture. The shear rate is 17s, the temperature profile is 20 to -40°C, 0.2°C/min. The results of the rheological study are given in FIG. It turns out that the hemimellitic acid ester 1 has a comparably good dynamic viscosity at low temperatures to the trimellitic acid ester T. Example 2: Determination of basic data of hemimellitic acid ester 1 im

Comparison to trimellitic acid ester 1'

The baseline data of hemimellitic ester 1 are measured and compared to the commercial trimellitic ester T esterified with the same alcohol mixture. The results are shown in the table below

Example 3-5

Preparation of further hemimellitic acid esters and a comparative ester (4')

Example 3:

A mixture of 140 g organic. Hemimellitic acid, 213 g 1-octanol, 142 g 1-dodecanol and 40 mL xylene in a 1 L three-necked flask combined with a water separator is refluxed at 1 atm. Within 2 hours the internal temperature rises from 125°C to 210°C 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 h and further at 215° C. for 3.5 h. A total of 37.7 g of water is continuously distilled off. The xylene and the excess alcohol are distilled off under reduced pressure (Tinn.=210° C., 10 mbar). The product (397.7 g) is obtained as a light yellow oil. Example 4:

A mixture of 129.9 g organic. Hemimellitic acid, 91.5 g 1-nonanol, 165.5 g 1-undecanol, 81 g Exxal 9 (ExxonMobil), 14.1 g Exxal 10 (ExxonMobil) and 50 mL xylene in a 1 L three-necked flask combined with a water separator , is refluxed at 1 atm. Within 2 hours the internal temperature rises from 124°C to 200°C and 0.5 g of tetraisopropyl orthotitanate (0.1% by weight) is added at an internal temperature of 160°C. The clear reaction mixture is then refluxed at 200° C. for 2.5 h and a total of 34.8 g of water are continuously distilled off. The xylene and excess alcohol are distilled off under reduced pressure (Tinn.=195° C., 13 mbar). After removing the catalyst, the product (377 g) is obtained as a light yellow oil.

Example 4' (TMA Ester 4', reference sample for example 4):

A mixture of 90 g petrochemical trimellitic acid, 63.5 g 1-nonanol, 114.7 g 1-undecanol, 56.1 g Exxal 9 (ExxonMobil), 9.76 g Exxal 10 (ExxonMobil) and 35 mL xylene in a 1 L three-necked flask combined with a water separator is refluxed at 1 atm. 0.35 g of tetraisopropyl orthotitanate (0.1 wt%) is added at an internal temperature of 145°C. The internal temperature rises from 159 °C to 195 °C within 2 hours. The clear reaction mixture is then refluxed at 195° C. for 4 h and a total of 25.0 g of water are continuously distilled off. The xylene and the excess alcohol are distilled off under reduced pressure (Tinn.=200° C., 19 mbar). After removing the catalyst, the product (295 g) is obtained as a light yellow oil.

Example 5:

A mixture of 150 g organic. Hemimellitic acid, 353.2 g 2-ethylhexan-1-ol and 40 mL xylene in a 1 L three-necked flask combined with a water separator is refluxed at 1 atm. Within 8 hours the internal temperature rises from 124°C to 210°C 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 h. A total of 39.1 g of water is continuously distilled off. The xylene and the excess Alcohol is distilled off under reduced pressure (tinn.=205° C., 16 mbar). The product (404.4 g) is obtained as a light yellow oil.

Three different hemimellitic acid esters are prepared by esterification of hemimellitic acid with different alcohols. Table 6 shows the alcohols used and the basic data obtained in comparison to the corresponding trimellitic esters.

Table 6a

Table 6b Example 6: Preparation of various lubricant compositions

Two lubricant compositions are prepared with the compositions described in Table 1:

Tab.1

Tab.2 Es zeigt sich, dass die erfindungsgemäße Schmierstoffzudammensetzung 2 auf Basis von Hemimellitsäureester vergleichbare Basisdaten wie die Vergleichszusammensetzung 1 auf Basis von Trimellitsäureester zeigen. Dabei sind die unterschiedlichen beobachteten Viskositäten durch die unterschiedlichen Ausgangsviskositäten der verwendeten Grundöle zu erklären. The basic data of the lubricant compositions are shown in Table 2.

Tab.2 It is found that the lubricant composition 2 according to the invention based on hemimellitic ester shows comparable basic data as the comparison composition 1 based on trimellitic ester. The different viscosities observed can be explained by the different initial viscosities of the base oils used.

Example 7: Determination of the oxidation stability of the lubricant compositions from example 6

The oxidation stability and the evaporation loss of the lubricant compositions from example 6 are determined by means of differential scanning calorimetry in accordance with DIN 51007 (04.2019) and thermogravimetric analysis in accordance with DIN 51006 (07.2005). The results are shown in Table 3.

Tab.3

It is found that the lubricant composition 2 according to the invention based on hemimellitic ester shows a comparably high oxidation stability as the comparison composition 1 based on trimellitic ester. Example 8: Thermal resistance tests

The lubricant compositions from Example 6 are examined with regard to their evaporation behavior and the increase in their apparently dynamic viscosity under thermal stress.

For this purpose, the evaporation behavior and the change in the apparently dynamic viscosity [mPas] as a criterion for progressive oxidation under thermal stress are determined as a comparative measurement. The sample quantity is 5 g (+/- 0.1 g) per test. After 72 hours of storage in an aluminum dish at 230°C in a convection oven, the samples are compared with one another.

In addition, the residue behavior after complete evaporation is determined using the Eisenmann test (250°C / 72h). For this purpose, the sample to be tested is weighed out with 5 g on a steel sheet that has previously been bent and cleaned with solvent and then evaporated at 250 °C in a circulating air drying cabinet for at least 72 hours. The square sheet metal is manually bent on all four sides to create a bowl shape. After cooling, the results of the backweigh are documented. Essential for this test is the determination of the solubility of the residue with fresh oil and the amount of residue formed. For this purpose, a drop of the fresh oil is applied to the residue and gently rubbed in using a rounded glass rod in circular movements.

The results are illustrated in Table 4.

Tab.4

[1 ] CP50, shear rate 300 s' ¹ , 25 °C

[2] CP25, shear rate 300 s' ¹ , 25 °C It turns out that all lubricant compositions have a very good performance. Lubricant compositions 2 according to the invention based on hemimellitic ester show comparably good or better evaporation behavior and an even smaller increase in dynamic viscosity after 72 hours at 230° C. than comparative composition 1 based on trimellitic ester. In addition, the lubricant composition according to the invention forms fewer residues. All residues can be easily dissolved with fresh oil.

Example 9: Measurement of the frictional wear of the lubricant compositions from example 6

The lubricant compositions from Example 6 are examined to measure the fretting using an oscillating fretting wear test (SRV). The coefficient of friction can be examined with the SRV. The SRV is standardized in DIN 51 834.

The lubricant compositions examined are measured in accordance with DIN 51 834 at 250N load, 50Hz, 165 min in a temperature step run (50 to 250°C). A steel ball is moved in an oscillating manner against a fixed steel disc on the front side. This allows the effect, resilience and service life of the lubricant compositions to be determined in oscillating movements under mixed friction conditions.

The results of the test are shown in Fig.2.

It is found that the lubricant compositions according to the invention based on hemimellitic ester exhibit a coefficient of friction that is comparably good to comparison composition 1 based on trimellitic ester.

Example 10 Production and testing of fat formulation 3 based on hemimellitic ester and comparison fat formulation 4 based on trimellitic ester

The fat formulation 3 according to the invention based on hemimellitic acid ester and the comparison fat formulation 4 based on trimellitic acid ester are formulated with the compositions shown in the table below.

Tab.5

Example 4, Table 6a is used as the hemellitic ester and TMA ester 4', Table 6a, as the trimellitic ester.

The baseline data of Fat Formulation 3 and Comparative Fat Formulation 4 are shown in the table below.

Tab.6

Both fat formulation 3 and comparison fat formulation 4 show comparably good flexing stability and shear stability. The water resistance, oil separation, noise ratio and water content of all formulations are on the same level.

Tab.7 Hochtemperatur-Eigenschaften von Fettformulierung 3 und Vergleichsfettformulierung 4 Example 11 : High temperature properties of fat formulation 3 and comparison fat formulation 4 The high temperature properties of Fat Formulation 3 and Comparative Fat Formulation 4 are examined. The results are shown in the table below.

Tab.7 High temperature properties of grease formulation 3 and comparative grease formulation 4

It turns out that both formulations have a dropping point of approx. 300°C in the high-temperature range. A comparably good result was obtained for both formulations in the copper corrosion test at 150°C and 160°C.

In addition, both laboratory samples show very good thermal stability in the FE9 test.

Example 11 Production and testing of fat formulations 5 based on hemimellitic acid ester and the comparison fat formulation

6 based on trimellitic acid ester

There are the fat formulation 5 based on the invention

Hemimellitic acid ester and the comparative fat formulation 6 based on Trimellitic acid ester formulated with the compositions shown in the table below.

Tab.8

The following alcohol mixture is used as the alcohol for the preparation of the hemimellitic acid ester Example 6:

25 wt% n-octanol 40 wt% 2EH-ol

35% by weight n-decanol

Claims

Claims Use of hemimellitic acid ester of the following general formula I

where Ri , R2 and R3 are independently a) an unsubstituted, branched or unbranched C1 to C20 alkyl group or b) a C1 to C5 alkyl group having at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups , Has, or c) a C5 to C20 aromatic group or a C5 to C20 cycloalkyl group, where the hemimellitic ester of the formula I can be present as a mixture of different compounds of the formula I, as a base oil of a lubricant composition for lubricating tribological systems. Use according to claim 1, characterized in that the hemimellitic acid ester of the formula I is at least partially bio-based. Use according to Claim 1 or 2, characterized in that the lubricant composition contains at least 10% by weight, for example from 10 to 100% by weight and/or 10 to 95% by weight, preferably at least 15% by weight, for example from 15% by weight. to 95% by weight, in particular at least 20% by weight, for example from 20 % by weight to 95% by weight of bio-based carbon, based on that Total weight of organic carbon in the lubricant composition. Use according to one or more of the preceding claims, characterized in that the hemimellitic acid ester of the formula I contains at least 30% by weight, for example from 30 to 100% by weight, preferably at least 40% by weight, for example from 40% by weight to 100% by weight. %, in particular at least 50% by weight, for example from 50% by weight to 100% by weight, of bio-based carbon, based on the total weight of the hemimellitic acid ester of the formula I, in the lubricant composition. Use according to one or more of the preceding claims, characterized in that the acid component of the hemimellitic acid ester of the formula I contains at least 30% by weight, preferably at least 40% by weight, for example from 40% by weight to 100% by weight, in particular at least 50% by weight. %, for example from 50% to 100% by weight, bio-based carbon based on the total weight of the acid component of the hemimellitic acid ester of formula I in the lubricant composition. Use according to one or more of the preceding claims, where at least one radical Ri , R2 and/or R3 is an unsubstituted, branched or unbranched C5 to C20 alkyl group, more preferably a C6 to C18 alkyl group and in particular a C8 to C18 is alkyl group. Use according to one or more of the preceding claims, characterized in that at least one radical Ri, R2 and / or Rs is a C1 - to C3-alkyl group and in particular a C1 - to C2- alkyl group, wherein the alkyl group has at least one substituent selected from the group consisting of C5 to C15 cycloalkyl groups and C5 to C15 aromatic groups. Use according to one or more of the preceding claims, characterized in that at least one group Ri , F and/or R3 is a methyl group, ethyl group or a propyl group linked to at least one C5 to C15 cycloalkyl group or to a C5 to C15 aromatic group is substituted. Use according to one or more of the preceding claims, characterized in that at least one R 1 , R 2 and/or R 3 radical is selected from the group consisting of octanyl, ethylhexanyl, nonanyl, decanyl, undecanyl, dodecanyl, isotridecyl, tricyclodecanemethyl, furfuryl. Use according to one or more of the preceding claims, characterized in that the hemimellitic acid ester of the formula I has R 1 , R 2 and R 3 radicals which are at least partly different from one another. Use according to one or more of the preceding claims, characterized in that the hemimellitic acid ester of the formula I is present as a mixture of different compounds of the formula I. Use according to one or more of the preceding claims, characterized in that the radicals Ri, R2 and R3 independently of one another have no atoms other than carbon and hydrogen. Use according to one or more of the preceding claims, characterized in that the lubricant composition contains the hemimellitic acid ester of the formula I in an amount of 20% by weight to 90% by weight, more preferably from 25% to 70% by weight, and even more preferably from 25% to 60% by weight and especially from 30 % by weight to 50% by weight, each based on the total weight of the lubricant composition. Use according to one or more of the preceding claims, characterized in that the hemimellitic acid ester of the formula I has a kinematic viscosity at 40°C [mmVsec] in the range from 30 mm ² /s to 150 mm ² /s. Use according to one or more of the preceding claims, characterized in that the lubricant composition contains 5 to 50% by weight, more preferably from 15 to 35% by weight and in particular from 15 to 30% by weight, in each case based on the total weight of the lubricant composition, polyisobutylene having. Use according to one or more of the preceding claims, characterized in that the lubricant composition is present as an oil formulation and at least one further base oil in a proportion of 10% by weight to 50% by weight, more preferably from 10% by weight to 40% by weight, contains in each case based on the total weight of the lubricant composition or that the lubricant composition is present as a grease formulation and at least one other base oil in a proportion of 10% by weight up to 50% by weight, more preferably from 25% by weight to 50% by weight and in particular from 30% by weight to 50% by weight, based in each case on the total weight of the lubricant composition. Use according to claim 16, characterized in that the further base oil is selected from esters, in particular esters of an aromatic and/or aliphatic di-, tri- or tetracarboxylic acid 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, as individual components or in any mixture as well as triglycerides and/or estolides, polyalphaolefins, polyethers and/or mineral oils. Lubricant composition designed as an oil formulation comprising: 20% by weight to 90% by weight, preferably 50% by weight to 85% by weight, of hemimellitic acid ester of the following general formula I

where Ri , F and R3 are independently a) an unsubstituted, branched or unbranched C1 to C20 alkyl group or b) a C1 to C5 alkyl group having at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups , Has, or c) a C5 to C20 aromatic group or a C5 to C20 cycloalkyl group, where the hemimellitic ester of the formula I can be present as a mixture of different compounds of the formula I, than base oil, 5 wt% to 50 wt%, preferably 10 wt% to 50 wt% polyisobutylene, 0.1% to 8% by weight additives. Lubricant composition designed as a grease formulation comprising: 20% by weight to 90% by weight of hemimellitic acid ester of the following general formula I

where Ri , F and R3 are independently a) a branched or unbranched C1 to C20 alkyl group or b) a C1 to C5 alkyl group containing at least one Substituents selected from the group consisting of Cycloalkyl groups and aromatic groups, or c) a C5 to C20 aromatic group or a C5 to C20 Are cycloalkyl group, where the hemimellitic acid ester of the formula I can be present as a mixture of different compounds of the formula I, as base oil, 3 to 30% by weight thickener, 0.1 to 8% by weight of additives. Lubricant composition designed as a grease formulation comprising: 20% by weight to 70% by weight of hemimellitic esters of the following general formula I where Ri, R2 and R3 are independently d) a branched or unbranched C1 to C20 alkyl group or e) a C1 to C5 alkyl group which is at least a Substituents selected from the group consisting of cycloalkyl groups and aromatic groups, or f) a C5 to C20 aromatic group or a C5 to C20 are cycloalkyl group, where the hemimellitic acid ester of the formula I can be present as a mixture of different compounds of the formula I, as a base oil, 3 to 30% by weight thickener, 10% by weight to 50% by weight of at least one further base oil 0.1 to 8% by weight of additives. Lubricant composition according to Claim 19 or 20, characterized in that the lubricant composition designed as a grease formulation has 10% by weight to 40% by weight of polyisobutylene.