USE OF HEMIMELLITIC ACID ESTER AS A BASE OIL FOR LUBRICANT COMPOSITIONS

Abstract

A use of a hemimellitic acid ester of formula I as a base oil a lubricant composition for lubricating tribological systems. In some embodiments, R.sub.1, R.sub.2 and R.sub.3, are independently of one another: a C.sub.5 to C.sub.20 aromatic group, a C.sub.5 to C.sub.20 cycloalkyl group, an unsubstituted, branched or unbranched C.sub.1 to C.sub.20 alkyl group, and/or a C.sub.1 to C.sub.5 alkyl group comprising at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups. In some embodiments, the hemimellitic acid ester of formula I is provided as a mixture of different compounds of formula I and/or the hemimellitic acid ester of formula I comprises groups R.sub.1, R.sub.2 and R.sub.3 at least partially differing from one another.

Claims

1. A use of a hemimellitic acid ester of the following general formula I ##STR00011## wherein R.sub.1, R.sub.2 and R.sub.3, are independently of one another: a C.sub.5 to C.sub.20 aromatic group, a C.sub.5 to C.sub.20 cycloalkyl group, an unsubstituted, branched or unbranched C.sub.1 to C.sub.20 alkyl group, and/or a C.sub.1 to C.sub.5 alkyl group comprising at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups wherein the hemimellitic acid ester of formula I is provided as a mixture of different compounds of formula I and/or the hemimellitic acid ester of formula I comprises groups R.sub.1, R.sub.2 and R.sub.3 at least partially differing from one another, as a base oil of a lubricant composition for lubricating tribological systems.

2. The use according to claim 1, wherein the hemimellitic acid ester of formula I is at least partially bio-based.

3. The use according to claim 1, wherein the lubricant composition includes at least 10 wt. %, from 10 to 100 wt. % from 10 to 95 wt. %, at least 15 wt. %, from 15 wt. % to 95 wt. %, at least 20 wt. %, and/or from 20 wt. % to 95 wt. % bio-based carbon, in relation to the overall weight of organic carbon in the lubricant composition.

4. The use according to claim 1, wherein the hemimellitic acid ester of formula I includes at least 30 wt. %, from 30 to 100 wt. %, at least 40 wt. %, from 40 wt. % to 100 wt. %, at least 50 wt. %, and/or from 50 wt. % to 100 wt. % bio-based carbon, in relation to the overall weight of the hemimellitic acid ester of formula I in the lubricant composition.

5. The use according to claim 1, wherein the acid component of the hemimellitic acid ester of formula I includes at least 30 wt. %, at least 40 wt. %, from 40 wt. % to 100 wt. %, at least 50 wt. %, and/or from 50 wt. % to 100 wt. % bio-based carbon, in relation to the overall weight of the acid components of the hemimellitic acid ester of formula I in the lubricant composition.

6. The use according to claim 1, wherein at least one residue R.sub.1, R.sub.2 and/or R.sub.3 is an unsubstituted, branched or unbranched C.sub.5 to C.sub.20 alkyl group, a C.sub.6 to C.sub.18 alkyl group and/or, a C.sub.8 to C.sub.18 alkyl group.

7. The use according to claim 1, wherein at least one residue R.sub.1, R.sub.2 and/or R.sub.3 is a C.sub.1 to C.sub.3 alkyl group a C.sub.1 to C.sub.2 alkyl group, wherein the alkyl group includes at least one substituent selected from the group consisting of C.sub.5 to C.sub.15 cycloalkyl groups and C.sub.5 to C.sub.15 aromatic groups.

8. The use according to claim 1, wherein at least one group R.sub.1, R.sub.2 and/or R.sub.3 is a methyl group, ethyl group or a propyl group substituted with at least one C.sub.5 to C.sub.15 cycloalkyl group or with at least one C.sub.5 to C.sub.15 aromatic group.

9. The use according to claim 1, wherein at least one residue R.sub.1, R.sub.2 and/or R.sub.3 is selected from the group consisting of octanyl, ethy lhexanyl, nonanyl, decanyl, undecanyl, dodecanyl, isotridecyl, tricyclodecanmethyl, and furfuryl.

10-11. (canceled)

12. The use according to claim 1, wherein the residues R.sub.1, R.sub.2 and R.sub.3 independently of one another include no other atoms but carbon and hydrogen.

13. The use according to claim 1, wherein the lubricant composition includes the hemimellitic acid ester of formula I in an amount of 20 wt. % to 90 wt. %, from 25 wt. % to 70 wt. %, from 25 wt. % to 60 wt. %, and/or from 30 wt. % to 50 wt. %, each in relation to the overall weight of the lubricant composition.

14. The use according to claim 1, wherein the hemimellitic acid ester of formula I has a kinematic viscosity at 40? C. in the range from 30 mm.sup.2/s to 150 mm.sup.2/s.

15. The use according to claim 1, wherein the lubricant composition includes 5 to 50 wt. %, from 15 to 35 wt. % and/or from 15 to 30 wt. % polyisobutylene in relation to the overall weight of the lubricant composition.

16. The use according to claim 1, wherein the lubricant composition is provided in the form of an oil formulation and includes at least one further base oil in a proportion of 10 wt. % to 50 wt. %, and/or from 10 wt. % to 40 wt. %, in relation to the overall weight of the lubricant composition, or wherein the lubricant composition is provided as a grease formulation and includes at least one further base oil in a proportion of 10 wt. % to 50 wt. %, from 25 wt. % to 50 wt. % and/or from 30 wt. % to 50 wt. %, in relation to the overall weight of the lubricant composition.

17. The use according to claim 16, wherein the further base oil is selected from esters, esters of an aromatic and/or aliphatic di-, tri- or tetracarboxylic acid with one C.sub.7 to C.sub.22 alcohols, esters of trimethylolpropane, pentaerythrite or dipentaerythrite with aliphatic C.sub.7 to C.sub.22 carboxylic acid, esters of C.sub.18 dimer acids with C.sub.7 to C.sub.22 alcohols, complex esters, as individual components or in any desired mixture, and triglycerides and/or estolides, polyalphaolefins, polyethers and/or mineral oils.

18. A lubricant composition, formed as an oil formulation, the lubricant composition comprising: 20 wt. % to 90 wt. %, and/or 50 wt. % to 85 wt. % hemimellitic acid ester of the following general formula I ##STR00012## wherein R.sub.1, R.sub.2 and R.sub.3, are independently of one another: an unsubstituted, branched or unbranched C.sub.1 to C.sub.20 alkyl group, a C.sub.5 to C.sub.20 aromatic group, a C.sub.5 to C.sub.20 cycloalkyl group, and/or a C.sub.1 to C.sub.5 alkyl group comprising at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups wherein the hemimellitic acid ester of formula I is provided as a mixture of different compounds of formula I and/or the hemimellitic acid ester of formula I comprises residues R.sub.1, R.sub.2 and R.sub.3 at least partially differing from on another, as a base oil; 5 wt. % to 50 wt. %, and/or 10 wt. % to 50 wt. % polyisobutylene; and 0.1 wt. % to 8 wt. % additives.

19. A lubricant composition, formed as a grease formulation, the lubricant composition comprising: 20 wt. % to 90 wt. % hemimellitic acid ester of the following general formula I ##STR00013## wherein R.sub.1, R.sub.2 and R.sub.3, are independently of one another: an unsubstituted, branched or unbranched C.sub.1 to C.sub.20 alkyl group, a C.sub.5 to C.sub.20 aromatic group, a C.sub.5 to C.sub.20 cycloalkyl group, and/or a C.sub.1 to C.sub.5 alkyl group comprising at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups, wherein the hemimellitic acid ester of formula I is provided as a mixture of different compounds of formula I and/or the hemimellitic acid ester of formula I comprises residues R.sub.1, R.sub.2 and R.sub.3 at least partially differing from one another, as a base oil;; 3 to 30 wt. % thickening agent; and 0.1 to 8 wt. % additives.

20. A lubricant composition, formed as a grease formulation, the lubricant composition comprising: 20 wt. % to 70 wt. % hemimellitic acid ester of the following general formula I ##STR00014## wherein R.sub.1, R.sub.2 and R.sub.3, are independently of one another; an unsubstituted, branched or unbranched C.sub.1 to C.sub.20 alkyl group, a C.sub.5 to C.sub.20 aromatic group, a C.sub.5 to C.sub.20 cycloalkyl group, and/or a C.sub.1 to C.sub.5 alkyl group comprising at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups, wherein the hemimellitic acid ester of formula I is provided as a mixture of different compounds of formula I and/or the hemimellitic acid ester of formula I comprises residues R.sub.1, R.sub.2 and R.sub.3 at least partially differing from one another, as a base oil;; 3 to 30 wt. % thickening agent; 10 wt. % to 50 wt. % at least one further base oil; and 0.1 to 8 wt. % additives.

21. The lubricant composition according to claim 17, wherein the lubricant composition, formed as a grease formulation, further comprises 10 wt. % to 40 wt. % polyisobutylene.

22. The lubricant composition according to claim 18, wherein the lubricant composition, formed as a grease formulation, further comprises 10 wt. % to 40 wt. % polyisobutylene.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Subject matter of the present disclosure will be described in even greater detail below based on the exemplary figures. All features described and/or illustrated herein can be used alone or combined in different combinations. The features and advantages of various embodiments will become apparent by reading the following detailed description with reference to the attached drawings, which illustrate the following:

[0047] FIG. 1 shows the dynamic viscosity of hemimellitic acid ester of formula I in comparison to trimellitic acid ester as a function of temperature; and

[0048] FIG. 2 shows the mean friction determined by means of SRV of a plurality of lubricant compositions containing hemimellitic acid ester of formula I in comparison to lubricant compositions containing trimellitic acid ester as a function of temperature.

DETAILED DESCRIPTION

[0049] The object of the present invention is to provide a base oil for a lubricant composition which can be extracted both from biological and from petrochemical sources. Furthermore, the resulting lubricant composition is to have good oxidation resistance, lubricant action and good low-temperature performance. In addition, it is to provide good lubricant action at constant high temperatures over a long period of time. Furthermore, the lubricant composition is to be provided in different grades of viscosity depending on the intended application.

[0050] The object is achieved according to the invention by the use of a hemimellitic acid ester of the following general formula I

##STR00006## [0051] wherein R.sub.1, R.sub.2 and R.sub.3, are independently of one another
a) an unsubstituted, branched or unbranched C.sub.1 to C.sub.20 alkyl group, or
b) a C.sub.1 to C.sub.5 alkyl group comprising at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups, or
c) a C.sub.5 to C.sub.20 aromatic group or a C.sub.5 to C.sub.20 cycloalkyl group, [0052] wherein the hemimellitic acid ester can be provided as a mixture of different compounds of formula I as a base oil of a lubricant composition for the lubrication of tribological systems.

[0053] Surprisingly, it has been found that the use of hemimellitic acid ester of the above formula as a base oil makes it possible to obtain a lubricant composition having good oxidation stability, lubricant action and good low-temperature performance. Moreover, it shows good lubrication properties even at constantly high temperatures over a long period of time. Furthermore, the lubricant composition can be provided with different grades of viscosity depending on the desired application. This was surprising because hemimellitic acid ester can be extracted from biological sources, and because bio-based lubricants, as explained above, mostly do not have the desired spectrum of properties in view of their oxidation stability, lubricant action and low-temperature performance.

[0054] The production of hemimellitic acid ester from biomass is well-known and described, for example, in U.S. Pat. No. 10,562,875B2. The thus obtained hemimellitic acid ester, depending on the raw materials used, can have a high proportion of bio-based carbon, or be completely bio-based. Hemimellitic acid ester can also be extracted, however, in a simple manner from petroleum or petrochemical sources, which increases flexibility during lubricant production.

[0055] In a preferred embodiment, the hemimellitic acid ester is at least partly bio-based. This means that the hemimellitic acid ester is at least partly made of raw materials derived from biological sources and/or renewable agricultural materials (including plant, animal and marine materials) rather than petroleum or petrochemical sources. Examples of biological sources are agriculture, forestry, horticulture or animal raw materials. Preferred biological sources are straw, animal waste, waste materials from agriculture and forestry.

[0056] In the lubricant composition, hemimellitic acid ester can be provided as a single base oil or in mixtures with further base oils.

[0057] A tribological system is a technical structure having a function implemented by structural elements, which are mechanically moved-and thus subject to friction and wear. Tribological systems have the function of converting movements, energy and material, as well as transporting them and making them technically useful. Preferred tribological systems are tribological systems including metallic and/or non-metallic materials, such as antifriction and plain bearings, in particular, antifriction and plain bearings in the automotive industry, conveying industry, mechanical engineering and/or office technology, transmissions, chains, sliding guides and joints, in particular wheel bearings of automotive vehicles, bearings in wind turbines, in particular rotor bearings, in wind turbines and/or rotating plain bearings, such as fan bearings, or linearly guided sliding-contact bearings and/or ball joints, in particular of ball joints for use in the automotive industry. Possible tribological systems further comprise sliding partners in industrial plants and machinery, but also in the fields of household machinery, consumer electronics, in particular, in oil-lubricated systems, lubrication of chains, chain sprockets and steel belts of continuous wood presses.

[0058] In a preferred embodiment, the tribological systems include surfaces containing metallic and/or non-metallic materials, preferably composite materials, aluminum, aluminum alloys, steel, stainless steel and cast materials, non-ferrous metals, plastic materials, fiber-reinforced plastics and/or polymers.

[0059] In a preferred embodiment of the invention, the lubricant composition includes at least 10 wt. %, for example from 10 to 100 wt. % and/or 10 to 95 wt. %, preferably at least 15 wt. %, for example from 15 wt. % to 95 wt. %, in particular at least 20 wt. %, for example from 20 wt. % to 95 wt. % bio-based carbon, in relation to the overall weight of organic carbon in the lubricant composition. Herein, the percentage of bio-based carbon can be determined by means of the ASTM International Radioisotope Standard D 6866 method. The newest version of the standard applies as valid on the application day. This method determines the bio-based percentage of a material on the basis of the amount of bio-based carbon in the material as a percentage of the weight of the overall organic carbon in the material tested. The method is based on the fact that bio-based products have carbon isotope ratios of 13 C/12 C and 14 C/12 C which differ from those which are found in materials derived from petroleum.

[0060] In a further preferred embodiment of the invention, the hemimellitic acid ester of formula I includes at least 30 wt. %, for example from 30 to 100 wt. %, preferably at least 40 wt. %, for example from 40 wt. % to 100 wt. %, in particular at least 50 wt. %, for example from 50 wt. % to 100 wt. % bio-based carbon, in relation to the overall weight of the hemimellitic acid ester of formula I in the lubricant composition, each measured in accordance with the ASTM International Radioisotope Standard D 6866 method. The newest version of the standard applies as valid on the application day.

[0061] In a further preferred embodiment of the invention, the acid component of the hemimellitic acid ester of formula I includes at least 30 wt. %, for example from 30 to 100 wt. %, preferably at least 40 wt. %, for example from 40 wt. % to 100 wt. %, in particular at least 50 wt. %, for example from 50 wt. % to 100 wt. % bio-based carbon, in relation to the overall weight of the acid components of the hemimellitic acid ester of formula I in the lubricant composition, each measured in accordance with the ASTM International Radioisotope Standard D 6866 method. The newest version of the standard applies as valid on the application day.

[0062] In a preferred embodiment of the invention, at least one residue R.sub.1, R.sub.2 and/or R.sub.3 is an unsubstituted, branched or unbranched C.sub.1 to C.sub.20 alkyl group, more preferably a C.sub.5 to C.sub.20 alkyl group, more preferably a C.sub.6 to C.sub.18 alkyl group and, in particular, a C.sub.5 to C.sub.18 alkyl group.

[0063] In a further particularly preferred embodiment of the invention, at least one residue R.sub.1, R.sub.2 and/or R.sub.3 is selected from the group consisting of octanyl, ethylhexanyl, nonanyl, decanyl, undecanyl, dodecanyl.

[0064] In a further particularly preferred embodiment of the invention, at least one residue R.sub.1, R.sub.2 and/or R.sub.3 is selected from the group consisting of octanyl, 2-ethylhexan-1-yl, 1-nonanyl, decanyl, 1-undecanyl, 1-dodecanyl.

[0065] In a further preferred embodiment of the invention, at least one residue R.sub.1, R.sub.2 and/or R.sub.3 is a C.sub.1 to C.sub.5 alkyl group and, preferably a C.sub.1 to C.sub.3 alkyl group, more preferably a C.sub.1 to C.sub.2 alkyl group and, in particular, a C.sub.1 alkyl group, which includes at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups. In the present embodiment, the above-mentioned number of carbon atoms of the alkyl group does not comprise the number of carbon atoms of the substituents. According to the invention, cycloalkyl groups comprise both monocyclic and polycyclic compounds.

[0066] Preferably, the substituents include independently of one another 5 to 19 carbon atoms, more preferably 5 to 17 carbon atoms and, in particular, 5 to 15 carbon atoms. Further preferably, the substituents are selected independently of one another 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, in particular, from C5 to C15 cycloalkyl groups, or C5 to C15 aromatic groups.

[0067] In a further preferred embodiment of the invention, at least one residue R.sub.1, R.sub.2 and/or R.sub.3 is a methyl group, ethyl group or a propyl group 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.

[0068] Particularly preferably, R.sub.1, R.sub.2 and R.sub.3 are independently of one another a methyl group 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.

[0069] In a further embodiment of the invention, at least one residue R.sub.1, R.sub.2 and/or R.sub.3 is a C5 to C20 aromatic group or a C5 to C20 cycloalkyl group. Preferably, at least one residue R.sub.1, R.sub.2 and/or R.sub.3 is selected from phenyl, cyclopentyl, cyclohexyl, naphthyl, isotridecyl, tricyclodecanmethyl, furfuryl.

[0070] In a particularly preferred embodiment of the invention, at least one residue R.sub.1, R.sub.2 and/or R.sub.3, preferably at least two residues R.sub.1, R.sub.2 and/or R.sub.3 and, in particular, all of the residues R.sub.1, R.sub.2 and/or R.sub.3 are selected from the group consisting of octanyl, ethylhexanyl, nonanyl, decanyl, undecanyl, dodecanyl, isotridecyl, tricyclodecanmethyl, furfuryl.

[0071] In a further particularly preferred embodiment of the invention, at least one residue R.sub.1, R.sub.2 and/or R.sub.3, preferably at least two residues R.sub.1, R.sub.2 and/or R.sub.3 and, in particular, all of the residues R.sub.1, R.sub.2 and/or R.sub.3 are selected from the group consisting of octanyl, 2-ethylhexan-1-yl, 1-nonanyl, decanyl, 1-undecanyl, 1-dodecanyl, isotridecyl, tricyclodecanmethyl, furfuryl.

[0072] The residues R.sub.1, R.sub.2 and R.sub.3 can be the same or different. In a further preferred embodiment, the hemimellitic acid ester of formula I includes residues R.sub.1, R.sub.2 and R.sub.3, which are at least partially different from one another. It is also preferred for the hemimellitic acid ester of formula I to be a mixture of different compounds of formula I.

[0073] Also preferably the residues R.sub.1, R.sub.2 and R.sub.3 independently of one another include no other atoms but carbon and hydrogen.

[0074] In a preferred embodiment of the invention, the lubricant composition includes the hemimellitic acid ester of formula I in an amount of 20 wt. % to 90 wt. %, more preferably from 25 wt. % to 70 wt. %, and even more preferably from 25 wt. % to 60 wt. % and, in particular, from 30 wt. % to 50 wt. %, each in relation to the overall weight of the lubricant composition.

[0075] In a further preferred embodiment of the invention, the hemimellitic acid ester of formula I has a kinematic viscosity at 40? C. [mm.sup.2/s] in the range from 30 mm.sup.2/s to 150 mm.sup.2/s, preferably from 30 mm.sup.2/s to 100 mm.sup.2/s, more preferably from 50 mm.sup.2/s to 150 mm.sup.2/s and, in particular, from 50 mm.sup.2/s to 90 mm.sup.2/s.

[0076] In a further preferred embodiment of the invention, the lubricant composition is provided as an oil formulation and has a kinematic viscosity at 40? C. [mm.sup.2/s] in the range from 100 mm.sup.2/s to 460 mm.sup.2/s, preferably from 150 mm.sup.2/s to 320 mm.sup.2/s.

[0077] In a further preferred embodiment of the invention, the lubricant composition is provided as a grease formulation and the hemimellitic acid ester of formula I and/or a mixture of hemimellitic acid ester of formula I and further base oils has a kinematic viscosity at 40? C. [mm.sup.2/s] in the range from 80 mm.sup.2/s to 460 mm.sup.2/s, preferably from 100 mm.sup.2/s to 320 mm.sup.2/s.

[0078] In a further preferred embodiment of the invention, the lubricant composition includes 5 to 50 wt. %, more preferably, from 15 to 35 wt. % and, in particular, from 15 to 30 wt. % polyisobutylene, each in relation to the overall weight of the lubricant composition. What is advantageous with the use of polyisobutylene is that, with it, the viscosity of the lubricant composition can be particularly easily adjusted. Moreover, in combination with the hemimellitic acid ester of formula I, a particularly good residue performance after complete evaporation can be achieved. According to a preferred embodiment, the polyisobutylene has an average (in numbers) molecular weight of 115 to 15,000 g/mol, preferably of 160 to 5,000 g/mol, measured in accordance with DIN 55672-1:2016-03 (gel permeation chromatography (GPC)part 1: tetrahydrofuran (THF) as an eluent).

[0079] As explained above, the lubricant composition can be provided both as a grease and as an oil formulation.

[0080] If the lubricant composition is provided as a grease formulation, it contains a thickening agent. In a preferred embodiment of the invention, the lubricant composition thus contains 3 to 30 wt. % thickening agent.

[0081] The thickening agent is preferably a reaction product of a diisocyanate, preferably 2,4-diisocyanate toluene, 2,6-diisocyanate toluene, 4,4-diisocyanato diphenylmethane, 2,4-diisocyanato phenyl methane, 4,4-diisocyanato diphenyl, 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.sub.2NR, or a diamine of the general formula R.sub.2NRNR.sub.2, wherein R is an aryl, alkyl or alkylene residue with 2 to 22 carbon atoms and R is identical or different, a hydrogen, an alkyl, alkylene or arylene residue, or with mixtures of amines and diamines.

[0082] In a further preferred embodiment, the thickening agent 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 thickening agents.

[0083] In addition to the hemimellitic acid ester of formula I the lubricant composition can contain at least one further base oil.

[0084] If the lubricant composition is provided as an oil formulation and contains at least one further base oil, the proportion of the further base oil is preferably from 10 wt. % to 50 wt. %, more preferably from 10 wt. % to 40 wt. %, even more preferably from 20 wt. % to 40 wt. % and, in particular, from 25 wt. % to 40 wt. %, each in relation to the overall weight of the lubricant composition.

[0085] If the lubricant composition is provided as a grease formulation and contains at least one further base oil, the proportion of the further base oil is preferably from 10 wt. % to 50 wt. %, more preferably from 25 wt. % to 50 wt. % and, in particular, from 30 wt. % to 50 wt. %, each in relation to the overall weight of the lubricant composition.

[0086] If the lubricant composition contains at least one further base oil, the lubricant composition preferably contains the hemimellitic acid ester of formula I in an amount of 20 wt. % to 70 wt. %, more preferably from 25 wt. % to 70 wt. %, and even more preferably from 25 wt. % to 60 wt. % and, in particular, from 30 wt. % to 50 wt. %, each in relation to the overall weight of the lubricant composition.

[0087] Suitable further base oils are usually lubrication oils liquid at room temperature (20? C.). The further base oil preferably has a kinematic viscosity of 18 mm.sup.2/s to 20000 mm.sup.2/s, in particular from 30 mm.sup.2/s to 400 mm.sup.2/s at 40? C. Base oils are differentiated between mineral and synthetic oils. Base oils are understood to be the usual base fluids used for the production of lubricants, oils, in particular, which can be categorized into groups I, II, II+, III, IV or V in accordance with the classification of the American Petroleum Institute (API) [NLGI Spokesman, N. Samman, Volume 70, Number 11, p. 14 and the following]. Mineral oils are classified in accordance with the API group. API group I are mineral oils consisting, for example, of naphthene basic or paraffin basic oils. When these mineral oils are chemically modified in comparison to the API group I oils, are low-aromatic, low-sulfur and have a low proportion of saturated compounds and thus improved viscosity/temperature performance, the oils are classified in API groups II and III. So-called gas-to-liquid oils also belong in group III, which are not produced from the refining of crude oil, but by the chemical conversion of natural gas. Furthermore, re-raffinates can also be used.

[0088] Examples of synthesis oils include polyethers, esters, polyesters, preferably polyalphaolefins, in particular, metallocene polyalphaolefins, perfluoropolyalkylethers (PFPAE), alkylated naphthalenes, silicone oils and alkylaromatics and mixtures thereof. The polyether compound can have free hydroxyl groups, but can also be completely etherized or end groups thereof esterized and/or produced of a starter compound with one or more hydroxy and/or carboxyl groups (COOH). Polyphenyl ethers, alkylated as the case may be, are also possible as sole components or, even better, as mixed components.

[0089] Esters of an aromatic and/or aliphatic di-, tri-, or tetracarboxylic acid with one C7 to C22 alcohol, or provided in a mixture thereof, esters of trimethylolpropane, pentaerythritol or dipentaerythritol with aliphatic C7 to C22 carboxylic acid, esters of C18 dimer acids with C7 to C22 alcohols, complex esters, as individual components or in any mixture can also be suitably used. Triglycerides and/or estolides are also preferred esters.

[0090] Silicone oils, native oils and derivatives of native oils are also suitable.

[0091] Further base oils particularly preferred according to the invention are esters, in particular, esters of an aromatic and/or aliphatic di-, tri-or tetracarboxylic acid, with tetracarboxylic acid with one C7 to C22 alcohol, or provided in a mixture thereof, esters of trimethylolpropane, pentaerythrite or dipentaerythrite with aliphatic C7 to C20 carboxylic acids, esters of C18 dimer acids with C7 to C22 alcohols, complex esters, as individual components or in any mixture, and triglycerides and/or estolides, polyalphaolefins, polyethers and/or mineral oils.

[0092] Furthermore, the lubricant composition can contain inorganic or organic solid lubricants, preferably in a proportion of 0.1 wt. % to 5 wt. %, preferably 0.1 wt. % to 3 wt. % in relation to the overall weight of the lubricant composition. Solid lubricants are preferred which are selected from PTFE, BN, pyrophosphate, Zn oxide, Mg oxide, pyrophosphates, thiosulfates, Mg carbonate, Ca carbonate, Ca stearate, Zn sulfide, Mo sulfide, W sulfide, Sn sulfide, graphites, graphene, nano-tubes, SiO2 modifications or a mixture thereof.

[0093] Further preferably, the lubricant composition contains 0.1 to 8 wt. % additives, selected from the group consisting of corrosion protection additives, antioxidants, wear protection additives, metal deactivators, ion complex formers and/or UV stabilizers.

[0094] The following compounds are particularly suitable antioxidants according to the invention: styrolized 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, benzolpropionic acid, sulfur-containing phenol compounds and mixtures of these components.

[0095] Suitable antioxidants are also compounds, which contain sulfur, nitrogen and/or phosphorus in the molecule. Preferred compounds, which contain sulfur, nitrogen and/or phosphorus in the molecule are selected from the group consisting of aromatic aminic antioxidants, such as alkylated phenyl-alpha-naphthylamine, dialkyldiphenylamine, sterically hindered phenols, such as butylhydroxytoluene (BHT), phenolic antioxidants with thio ether groups, Zn or Mo or W dialkyldithiophosphates and phosphites.

[0096] Preferred corrosion protection additives, metal deactivators and/or ion complex formers are triazols, imidazolines, N-methylglycine (Sarcosine), benzotriazole derivatives, N,N-bis(2-ethylhexyl)-ar-methyl-1 H benzotriazol-1-methanamine; n-methyl-N(1-oxo-9-octadecenyl) glycine, a mixture of phosphoric acid and mono-and diisooctyl ester converted with (C11-C14) alkyl amines, a mixture of phosphoric acid and mono-and diisooctyl ester, converted with tert-alkylamine and primary (C12-C14) amines, dodecanoic acid, triphenyl phosphorothionate and amine phosphates and mixtures thereof. Commercially available additives are the following: 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.

[0097] Preferred wear protection additives include amines, amine phosphates, phosphates, thiophosphates, phosphorothioates and mixtures of these components. Preferred wear protection additives are selected from the group consisting of anti-wear additives on the basis of diphenylkresylphosphate, amine neutralized phosphates, alkylated and non-alkylated triaryl phosphates, alkylated and non-alkylated triaryl thiophosphates, Zn- or Mo or W-dialkyl dithio phosphates, carbamates, thiocarbamates, Zn- or Mo- or W-dithio carbamates, dimercapto thiadiazol, calcium sulfonates and benzotriazole derivatives. The commercially available wear protection additives include IRGALUBE? TPPT, IRGALUBE? 232, IRGALUBE? 349, IRGALUBE? 211 and ADDITIN? RC3760 Liq 3960, FIRC-SHUN? FG 1505 and FG 1506, NA-LUBER KR-015FG, LUBEBOND?, FLUORO? FG, SYNALOX? 40-D, ACHESON? FGA 1820 and ACHESON? FGA 1810.

[0098] A further subject matter of the invention is a lubricant composition, formed as an oil formulation, comprising: [0099] 20 wt. % to 90 wt. %, preferably 50 wt. % to 85 wt. %, hemimellitic acid ester of the following general formula I

##STR00007## [0100] wherein R.sub.1, R.sub.2 and R.sub.3, are independently of one another
a) a branched or unbranched C.sub.1 to C.sub.20 alkyl group, or
b) a C.sub.1 to C.sub.5 alkyl group comprising at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups, or
c) a C.sub.5 to C.sub.20 aromatic group or a C.sub.5 to C.sub.20 cycloalkyl group, [0101] wherein the hemimellitic acid ester of formula I is provided as a mixture of different compounds of formula I, as a base oil, [0102] 5 wt. % to 50 wt. %, preferably 10 wt. % to 50 wt. % polyisobutylene, [0103] 0.1 wt. % to 8 wt. % additives.

[0104] In a further preferred embodiment, the lubricant composition provided as an oil formulation additionally includes 10 wt. % to 45 wt. %, preferably 30 wt. % to 45 wt. % of at least one further base oil.

[0105] A further subject matter of the invention is a lubricant composition, formed as a grease formulation, comprising: [0106] 20 wt. % to 90 wt. %, preferably 30 wt. % to 90 wt. %, more preferably 40 wt. % to 90 wt. %, hemimellitic acid ester of the following general formula I

##STR00008## [0107] wherein R.sub.1, R.sub.2 and R.sub.3, are independently of one another
a) a branched or unbranched C.sub.1 to C.sub.20 alkyl group, or
b) a C.sub.1 to C.sub.5 alkyl group comprising at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups, or
c) a C.sub.5 to C.sub.20 aromatic group or a C.sub.5 to C.sub.20 cycloalkyl group, wherein the hemimellitic acid ester of formula I is provided as a mixture of different compounds of formula I, as a base oil, [0108] 3 to 30 wt. % thickening agent, [0109] 0.1 wt. % to 8 wt. % additives.

[0110] A further subject matter of the invention is a lubricant composition, formed as a grease formulation, comprising: [0111] 20 wt. % to 70 wt. %, preferably 30 wt. % to 70 wt. %, more preferably 40 wt. % to 70 wt. % hemimellitic acid ester of the following general formula I

##STR00009## [0112] wherein R.sub.1, R.sub.2 and R.sub.3, are independently of one another
d) a branched or unbranched C.sub.1 to C.sub.20 alkyl group, or
e) a C.sub.1 to C.sub.5 alkyl group comprising at least one substituent selected from the group consisting of cycloalkyl groups and aromatic groups, or
f) a C.sub.5 to C.sub.20 aromatic group or a C.sub.5 to C.sub.20 cycloalkyl group, wherein the hemimellitic acid ester of formula I is provided as a mixture of different compounds of formula I, as a base oil, [0113] 3 to 30 wt. % thickening agent, [0114] 10 wt. % to 50 wt. % at least one further base oil, [0115] 0.1 to 8 wt. % additives.

[0116] In a preferred embodiment, the lubricant composition provided as a grease formulation includes 10 wt. % to 40 wt. % polyisobutylene.

[0117] In a further preferred embodiment, the lubricant composition provided as a grease formulation includes 0.1 wt. % to 5 wt. % inorganic or organic solid lubricants.

[0118] Preferred components of the lubricant composition according to the invention are those mentioned in the context of the use according to the invention.

[0119] In particular, particularly preferred thickening agents for the lubricant composition provided as a grease formulation are a reaction product of diisocyanate, preferably 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4-diisocyanatodiphenylmethane, 2,4-diisocyanatophenyl-methane, 4,4-diisocyanatodi-phenyl, 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.sub.2NR, or a diamine of the general formula R.sub.2NRNR.sub.2, wherein R is an aryl, alkyl or alkylene residue with 2 to 22 carbon atoms and R is identical or different from hydrogen, is an alkyl, alkylene or aryl residue, or with mixtures of amines and diamines.

[0120] In a further preferred embodiment, the thickening agent 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 thickening agents.

[0121] Furthermore, particularly preferred further base oils for the lubricant composition according to the invention provided 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 tetracarboxylic acid with one C7 to C22 alcohol, or provided in a mixture thereof, esters of trimethylolpropane, pentaerythritol or dipentaerythritol with aliphatic C7 to C22 carboxylic acid, esters of C18 dimer acids with C7 to C22 alcohols, complex esters, as individual components or in any mixture, and triglycerides and/or estolides, polyalphaolefins, polyethers and/or mineral oils.

Measuring Methods

Viscosity

[0122] Viscosity is measured in accordance with DIN 51562 (2018) using a Stabinger viscosimeter SVM 3000 (Anton Paar).

Bio-Based Carbon Content

[0123] The content of bio-based carbon is determined by means of the ASTM International Radioisotope Standard D 6866 method in the version valid on the day of application.

[0124] The invention will be described in more detail in the following with reference to examples not limiting the invention.

EXAMPLE 1: DETERMINATION OF THE DYNAMIC VISCOSITY OF HEMIMELLITIC ACID ESTER OF FORMULA I IN COMPARISON WITH TRIMELLITIC ACID ESTER

[0125] The hemimellitic acid ester 1 is produced by the following reaction:

##STR00010##

Example 1-A

[0126] A mixture of 150 g bio-based hemimellitic acid, 369.6 g Nafol 810D and 60 ml xylol in a 1 l-three-necked flask, combined with a water separator, is refluxed at 1 atm. Within 4 h, the internal temperature rises from 126? C. to 200? C., and 0.52 g tetraisopropyl orthotitanate (0.1 wt. %) is added at an internal temperature of 160? C. Then, the clear reaction mixture is refluxed at 200? C. for 2 h and an overall amount of 38.8 g water is continuously distilled off. The xylol and the excess alcohol are distilled off at reduced pressure (T.sub.int.=200? C., 10 mbar). After removal of the catalyst, the product (407.7 g) is obtained as a light-yellow oil.

Example 1-B

[0127] A mixture of 150 g bio-based hemimellitic acid, 369.6 g Nafol 810D and 45 ml xylol in a 1 l-three-necked flask, combined with a water separator, is refluxed at 1 atm. Within 2 h, the internal temperature rises from 139? C. to 210? C., and 0.026 g tetraisopropyl orthotitanate (0.005 wt. %) is added at an internal temperature of 150? C. Then, the clear reaction mixture is refluxed at 210? C. for 7.5 h and an overall amount of 39.6 g water is continuously distilled off. The xylol and the excess alcohol are distilled off at reduced pressure (T.sub.int.=200? C., 8 mbar). The product (415 g) is obtained as a light-yellow oil.

Example 1-C

[0128] A mixture of 140 g bio-based hemimellitic acid, 375.1 g Nafol 810D and 40 ml xylol in a 1 l-three-necked flask, combined with a water separator, is refluxed at 1 atm. Within 5 h, the internal temperature rises from 130? C. to 215? C. Then, the clear reaction mixture is refluxed at 215? C. for 2 h and further at 220? C. for 6 h. An overall amount of 35.4 g water is continuously distilled off. The xylol and the excess alcohol are distilled off at reduced pressure (T.sub.int.=210? C., 8 mbar). The product (388 g) is obtained as a light-yellow oil.

[0129] The dynamic viscosity of the hemimellitic acid ester 1-B is measured as a function of temperature and compared with the commercially available trimellitic acid ester 1 which was esterized with the same alcohol mixture. The shearing rate is 1?/s, the temperature profile is 20 to ?40? C., 0.2? C./min. The results of the rheological test are shown in FIG. 1. It has been found that the hemimellitic acid ester 1 has a comparable dynamic viscosity at low temperatures that is as good as that of the trimellitic acid ester 1.

EXAMPLE 2: DETERMINATION OF BASE DATA OF HEMIMELLITIC ACID ESTER 1 IN COMPARISON WITH TRIMELLITIC ACID ESTER 1

[0130] The base data of the hemimellitic acid ester are measured and compared to the commercially available trimellitic acid ester 1, which was esterized with the same alcohol mixture. The results are shown in the following table.

TABLE-US-00001 TMA Ester 1 Ex. 1-A Ex. 1-B Ex. 1-C (commercial) alcohols n-C8 (45%), n-C10 (55%) Kin. Visco. 40? C. 64.6 62.2 63.6 51.1 [mm.sup.2/sec] Kin. Visco. 8.77 8.55 8.58 8.01 100? C. [mm.sup.2/sec] VI +108.8 +109.0 +106.4 +126.3 SZ [mg KOH/g] 0.15 0.26 3.77 0.10

EXAMPLES 3-5

[0131] Production of further hemimellitic acid esters and one comparative ester (4)

Example 3

[0132] A mixture of 140 g bio-based hemimellitic acid, 213 g 1-octanol, 142 g 1-dodecanol and 40 ml xylol in a 1 l-three-necked flask, combined with a water separator, is refluxed at 1 atm. Within 2 h, the internal temperature rises from 125? C. to 210? C., and 0.025 g tetraisopropyl orthotitanate (0.005 wt. %) is added at an internal temperature of 145? C. Then, the clear reaction mixture is refluxed at 210? C. for 4 h and further at 215? C. for 3.5 h. An overall amount of 37.7 g water is continuously distilled off. The xylol and the excess alcohol are distilled off at reduced pressure (T.sub.int.=210? C., 10 mbar). The product (397.7 g) is obtained as a light-yellow oil.

Example 4

[0133] A mixture of 129.9 g bio-based hemimellitic acid, 91.5 g 1-nonanol, 165.5 g 1-undecanol, 81 g Exxal 9 (ExxonMobil), 41.1 g Exxal 10 (ExxonMobil) and 50 ml xylol in a 1 l-three-necked flask, combined with a water separator, is refluxed at 1 atm. Within 2 h, the internal temperature rises from 124? C. to 200? C., and 0.5 g tetraisopropyl orthotitanate (0.1 wt. %) is added at an internal temperature of 160? C. Then, the clear reaction mixture is refluxed at 200? C. for 2.5 h and an overall amount of 34.8 g water is continuously distilled off. The xylol and the excess alcohol are distilled off at reduced pressure (T.sub.int.=195? C., 13 mbar). After removal of the catalyst, the product (377 g) is obtained as a light-yellow oil.

Example 4 (TMA Ester 4, Reference Sample for Example 4)

[0134] 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 xylol in a 1 l-three-necked flask, combined with a water separator, is refluxed at 1 atm and 0.35 g tetraisopropyl orthotitanate (0.1 wt. %) is added at the internal temperature of 145? C. Within 2 h, the internal temperature rises from 159? C. to 195? C. Then, the clear reaction mixture is refluxed at 195? C. for 4 h and an overall amount of 25.0 g water is continuously distilled off. The xylol and the excess alcohol are distilled off at reduced pressure (T.sub.int.=200? C., 19 mbar). After removal of the catalyst, the product (295 g) is obtained as a light-yellow oil.

Example 5

[0135] A mixture of 150 g bio-based hemimellitic acid, 353.2 g 2-ethylhexane-1-ol and 40 ml xylol in a 1 l-three-necked flask, combined with a water separator, is refluxed at 1 atm. Within 8 h, the internal temperature rises from 124? C. to 210? C. and 0.025 g tetraisopropyl orthotitanate (0.005 wt. %) is added at an internal temperature of 145? C. Then, the clear reaction mixture is refluxed at 210? C. for 5.5 h. An overall amount of 39.1 g water is continuously distilled off. The xylol and the excess alcohol are distilled off at reduced pressure (T.sub.int.=205? C., 16 mbar). The product (404.4 g) is obtained as a light-yellow oil.

[0136] Three different hemimellitic acid esters are produced by esterizing hemimellitic acid with different alcohols. The alcohols used and the obtained base data in comparison to corresponding trimellitic acid esters are shown in Table 6.

TABLE-US-00002 TABLE 6 TMA Ester 3 TMA Ester 4 Ex. 3 (commercial) Ex. 4 (Ex. 4) alcohols n-C8 (60%). n-C12 (40%) n-C9 (25-27%). i-C9 (23%) i-C10 (3-4%). n-C11 (47%) Kin. Visco. 40? C. 64.1 51.4 81.0 65.6 [mm.sup.2/sec] Kin. Visco. 8.89 8.17 10.0 9.46 100? C. [mm.sup.2/sec] VI +113.1 +130.2 +104.1 +123.6 SZ [mg KOH/g] 0.55 0.20 0.30 0.27 Pour point ?51? C. ?48? C. ?54? C. TMA Ester 5 Ex. 5 (commercial) Ex. 6 alcohols 2-ethylhexane-1-ol 25 wt. % n-octanol 40 wt. % 2EH- 35 wt. % n-decanol Kin. Visco. 40? C. 125.8 92.1 78.6 [mm.sup.2/sec] Kin. Visco. 11.0 9.70 9.3 100? C. [mm.sup.2/sec] VI +61.0 +79.0 93 SZ [mg KOH/g] 0.43 0.10 0.35 Pour point ?48? C. ?36? C. ?54? C.

EXAMPLE 6: PRODUCTION OF VARIOUS LUBRICANT COMPOSITIONS

[0137] Two lubricant compositions are produced with the composition described in Table 1:

TABLE-US-00003 TABLE 1 comparative composition 2 acc. composition 1 to the invention ester oil 41.985 wt. % trimellitic 41.985 wt. % hemimellitic acid ester 1 acid ester (commercial) Example 1-B polyisobutylene 16.7 wt. % 16.7 wt. % group III oil 37.61 wt. % 37.61 wt. % foam inhibitor 0.02 wt. % 0.02 wt. % additive package 3.685 wt. % 3.685 wt. %

[0138] The base data of the lubricant compositions are shown in Table 2.

TABLE-US-00004 TABLE 2 composition 2 comparative acc. to the requirement composition 1 invention appearance clear, yellow clear, light orange kinematic viscosity 260 268.5 290.9 40? C. [mm.sup.2/sec] kinematic viscosity 27.4-30.6 30.1 30.6 100? C. [mm.sup.2/sec] viscosity index at least 140 +150.5 +143.6 density 20? C. 0.9107 0.9120 Pour point max. ?20? C. <?30? C. <?30? C. copper corrosion max. 2-150 1b - 150 1b - 150 (24 h/150? C.)

[0139] It turns out that the lubricant composition 2 according to the invention on the basis of hemimellitic acid ester shows base data comparable to those of the comparative composition 1 on the basis of trimellitic acid ester. The different viscosities that can be seen can be explained by the different initial viscosities of the base oils used.

EXAMPLE 7: DETERMINATION OF THE OXIDATION STABILITY OF THE LUBRICANT COMPOSITIONS OF EXAMPLE 6

[0140] The oxidation stability and the evaporation loss of the lubricant compositions of 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.

TABLE-US-00005 TABLE 3 comparative composition 2 acc. composition 1 to the invention 180? C. (wt. %) 0.3 0.2 200? C. (wt. %) 0.8 0.7 220? C. (wt. %) 1.9 1.7 240? C. (wt. %) 4.2 4.0 260? C. (wt. %) 8.8 8.5 280? C. (wt. %) 17.5 17.0 300? C. (wt. %) 45.2 43.1 oxidation start 207? C. 207? C.

[0141] It turns out that the lubricant compositions 2 according to the invention on the basis of hemimellitic acid ester shows high oxidation stability comparable to those of the comparative composition 1 on the basis of trimellitic acid ester.

EXAMPLE 8: THERMAL STABILITY TESTS

[0142] The lubricant compositions of Example 6 are tested in view of their evaporation behavior and the increase in their apparent dynamic viscosity under thermal stress.

[0143] To do this, the evaporation behavior and the change in the apparent dynamic viscosity (mPas) is determined as a criterion of progressive oxidation under thermal stress as a comparative measurement. Per test the specimen amount is 5 g (?0.1 g). The specimens are compared to one another after 72 h storage in an aluminum dish at 230? C. in an air-circulating oven.

[0144] In addition, the residue behavior after complete evaporation is determined with the Eisenmann test (250? C./72 h). To do this, the specimen to be tested is weighed at 5 g onto a steel sheet bent to shape and cleaned with solvent, and then evaporated off at 250? C. in an air-circulating cabinet for at least 72 h. The square metal sheet is manually bent on all four sides so that a dish shape is created. After cooling down, the results of the residual weight were documented. Key for this type of test is the determination of the partial solubility of the residue with fresh oil and the amount of the residue formed. For this purpose, a drop of the fresh oil is applied to the residue and gently rubbed in by means of a rounded glass bar in circular movements.

[0145] The results are illustrated in Table 4.

TABLE-US-00006 TABLE 4 comparative composition 2 acc. composition 1 to the invention evaporation loss with 27.0 wt. % 25.8 wt. % closed dishes (72 h/230? C.). dynamic viscosity.sup.[1] of the 559 mPa .Math. s 624 mPa .Math. s original formulation dynamic viscosity .sup.[2] after 4617 mPa .Math. s 3947 mPa .Math. s 72 h at 230? C. full evaporation acc. to good solubility good solubility Eisenmann category 4 category 4 (250? C./72 h) solubility of the residues full evaporation acc. to 6.2 wt. % 4.7 wt. % Eisenmann (250? C./72 h) percentage of the residues .sup.[1]CP50, shearing rate 300 s.sup.?1, 25? C. .sup.[2] CP25, shearing rate 300 s.sup.?1, 25? C.

[0146] It turns out that all of the lubricant compositions have excellent performance. The lubricant compositions 2 according to the invention on the basis of hemimellitic acid ester show comparable evaporation behavior that is as good as, or even better than, that of the comparative composition 1 on the basis of trimellitic acid ester, and an even smaller increase of the dynamic viscosity after 72 h at 230? C. Moreover, the lubricant composition according to the invention forms a smaller amount of residue. All of the residues are excellently partially soluble with fresh oil.

EXAMPLE 9: MEASUREMENT OF FRICTIONAL WEAR OF THE LUBRICANT COMPOSITIONS OF EXAMPLE 6

[0147] The lubricant compositions of Example 6 are tested with a linear-oscillating friction and wear test (SRV) to measure frictional wear. The SRV can be used to test the coefficient of friction. The SRV is standardized in DIN 51 834.

[0148] The tested lubricant compositions are measured following DIN 51 834 at 250N load, 50 Hz, 165 min in a stepped-temperature cycle (50 to 250? C.). In this test, a steel ball is moved in oscillation against the end side of a fixedly mounted steel disc. By these means, the effect, load carrying capacity and useful life can be determined with oscillating movements under mixed friction conditions.

[0149] The results of the test are shown in FIG. 2.

[0150] It turns out that the lubricant compositions according to the invention on the basis of hemimellitic acid ester have a comparable frictional value that is as good as that of the comparative composition 1 on the basis of trimellitic acid ester.

EXAMPLE 10: PRODUCTION AND TEST OF THE GREASE FORMULATION 3 ON THE BASIS OF HEMIMELLITIC ACID ESTER AND THE COMPARATIVE GREASE FORMULATION 4 ON THE BASIS OF TRIMELLITIC ACID ESTER

[0151] The grease formulation 3 according to the invention on the basis of hemimellitic acid ester and the comparative grease formulation 4 on the basis of trimellitic acid ester are formulated with the compositions shown in the following Table.

TABLE-US-00007 TABLE 5 comparative grease formulation 4 grease formulation 3 ester base oil 82 wt. % 82 wt. % trimellitic acid ester hemimellitic acid ester (Example 4) (Example 4) urea thickening 15 wt. % 15 wt. % agent antioxidant 0.50 wt. % 0.50 wt. % corrosion 2.5 wt. % 2.5 wt. % protection

[0152] Example 4, Table 6a is used as the hemimellitic acid ester and TMA ester 4 of Table 6a is used as the trimellitic acid ester.

[0153] The base data of the grease formulation 3 and the comparative grease formulation 4 are shown in the following Table.

TABLE-US-00008 TABLE 6 comparative grease grease performance formulation 4 TMA formulation 3 profile ester bio. HMA ester worked 250-280 [0.1 mm] 256 [0.1 mm] 265 [0.1 mm] penetration, 60 dT DIN ISO 2137 worked max. 370 281 [0.1 mm] 287 [0.1 mm] penetration, 10.sup.5 dT [0.1 mm] DIN ISO 2137 Delta worked +25 [0.1 mm] +22 [0.1 mm] penetration DIN ISO 2137 penetration at rest min. 220 243 [0.1 mm] 252 [0.1 mm] DIN ISO 2137 [0.1 mm] shear stability max. +60 241 [0.1 mm] 253 [0.1 mm] 2 h @ 130? C. [0.1 mm] 264 [0.1 mm] 271 [0.1 mm] +23 [0.1 mm] +18 [0.1 mm] shear viscosity @ 2000-4000 2707 mPa .Math. s 4271 mPa .Math. s 25? C. mPas DIN 51810 water resistance 0 0 0 3 h @ 90? C. DIN 51807-1 oil separation max. 3.00% 1.99% 2.52% 7 d @ 40? C. DIN 51817 oil separation max. 5.00% 0.74% 0.81% 30 h @ 150? C. ASTM D 6184 Emcor max. 1 0 0 168 h, demi. water following DIN 51802 R0F appr. 700000 837500 mm/min 1005000 mm/min speed factor mm/min Anderon max. 2/3 Start: 1 Start: 1 Damping: 2 Damping: 3 Peak: 1 Peak: 1 SKF BQ + Noise GN3 96, 100, 100, 100 97, 100, 100, 100 Class ?NORM GN4 GN4 M8127 p2 water content max. 0.40% 0.051% 0.069% Karl-Fischer

[0154] Both the grease formulation 3 and the comparative grease formulation 4 show comparative good working stability and shear stability. The water resistance, oil separation, noise ratio and water content of all formulations are at the same level.

EXAMPLE 11: HIGH-TEMPERATURE PROPERTIES OF THE GREASE FORMULATION 3 AND THE COMPARATIVE GREASE FORMULATION 4

[0155] The high-temperature properties of the grease formulation 3 and the comparative grease formulation 4 are studied. The results are shown in the following table.

TABLE-US-00009 TABLE 7 High-temperature properties of the grease formulation 3 and the comparative grease formulation 4 comparative performance grease grease profile formulation 4 formulation 3 dropping point min. 250? C. 299.0? C. 301.3? C. DIN ISO 2176 copper corrosion max. 2 1 1 24 h @ 160? C. DIN 51811 copper corrosion max. 1 1 1 24 h @ 150? C. DIN 51811 FE9 L50: min. 100 h L10: 224 h L10: 253 h B, 1500N, 6000 L50: 268 h L50: 333 h rpm, 180? C. ?: 10.6 ?: 6.9 DIN 51821

[0156] It turns out that, in the high-temperature domain, both formations have a dropping point of about 300? C. In the copper corrosion test at 150? C. and 160? C., a comparatively good result is obtained for both formulations. Moreover, both laboratory specimens show very good thermal stability in the FE9 test.

EXAMPLE 11: PRODUCTION AND TEST OF THE GREASE FORMULATIONS 5 ON THE BASIS OF HEMIMELLITIC ACID ESTER AND THE COMPARATIVE GREASE FORMULATION 6 ON THE BASIS OF TRIMELLITIC ACID ESTER

[0157] The grease formulation 5 on the basis of hemimellitic acid ester and the comparative grease formulation 6 on the basis of trimellitic acid ester are formulated with the compositions shown in the following Table.

TABLE-US-00010 TABLE 8 comparative grease formulation grease formulation 5 6 TMA ester bio. HMA ester ester base oil 87 wt. % 87 wt. % trimellitic acid ester A hemimellitic acid ester Example 6 urea thickening 10 wt. % 10 wt. % agent aminic antioxidant 0.50 wt. % 0.50 wt. % corrosion protection 0.75 wt. % 0.75 wt. % wear protection 1.75 wt. % 1.75 wt. %

[0158] The following alcohol mixture is used as an alcohol for the production of the hemimellitic acid ester of Example 6: [0159] 25 wt. % n-octanol [0160] 40 wt. % 2EH-ol [0161] 35 wt. % n-decanol

TABLE-US-00011 comparative grease grease formulation 6 formulation 5 Method Parameter Standard (TMA ester) (HMA ester) composition ester ester thickening agent Urea Urea water content Karl- 0.059% 0.072% Fischer working @ 25? C., DIN ISO 303 [0.1 mm] 303 [0.1 mm] penetration 60 ds 2137 working @ 25? C., DIN ISO 360 [0.1 mm] 343 [0.1 mm] penetration 100,000 ds 2137 shear viscosity @ 25? C. DIN 51810 3195 4325 base oil viscosity @ 40? C. DIN 51562 71.1 mm.sup.2/s 80.5 mm.sup.2/s base oil viscosity @ 100? C. DIN 51562 7.38 mm.sup.2/s Cu corrosion 24 h @ DIN 51811 1 1 160? C. Emcor 168 h, dist DIN 51802 0 0 water oil separation 7 d @ 40? C. DIN 51817 2.49% 2.43% oil separation 30 h @ ASTM D 1.27% 2.64% 150? C. 6184 flow pressure @ ?40? C. DIN 51805-2 475 mbar 475 mbar flow pressure @ ?45? C. DIN 51805-2 675 mbar 650 mbar low-temperature @?45? C.; IP 186 234 Nmm 196 Nmm torque start/run 116 Nmm 89 Nmm dropping point DIN ISO 277.3? C. 270.4? C. 2176 noise behavior II II MoreQuiet noise behavior 1 1 MoreQuiet noise behavior noise class GN1 GN1 SKF BQ+ R0F speed factor 837.500 mm/min 1.005.000 mm/min FE9 B, 1500N, DIN 51821 PK1 529 h PK1 380 h 6000 rpm, PK2 395 h PK2 >547 h 180? C. PK3 272 h PK3 >547 h PK4 473 h PK4 >547 h PK5 624 h PK5 >547 h water resistance 3 h @ 90? C. DIN 51807-1 0-90 0-90 RapidOxy Test 160? C., 30% 16.6 h 16 h pressure loss

[0162] While subject matter of the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Any statement made herein characterizing the invention is also to be considered illustrative or exemplary and not restrictive as the invention is defined by the claims. It will be understood that changes and modifications may be made, by those of ordinary skill in the art, within the scope of the following claims, which may include any combination of features from different embodiments described above.

[0163] The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article a or the in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of or should be interpreted as being inclusive, such that the recitation of A or B is not exclusive of A and B, unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of at least one of A, B and C should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of A, B and/or C or at least one of A, B or C should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.