Lubricating grease

Abstract

The invention relates to a lubricating grease comprising - between 30 wt.-% and 60 wt.-% silicone oil, - between 10 wt.-% and 35 wt.-% polyalphaolefin, and - between 10 wt.-% and 45 wt.-% overbased calcium sulfonate thickener, the specified amounts being relative to the total weight of the lubricating grease.

Description

[0001] Grease

[0002] The invention relates to a lubricating grease containing silicone oil and polyalphaolefin as base oils. The invention further relates to its use for the lubrication of tribological systems, in particular tribological systems with high energy efficiency requirements, even at low or high temperatures, and / or tribological systems that come into contact with food and / or drinking water. The lubricating grease can achieve good energy efficiency, even at low or high temperatures, and good friction values ​​even without containing PTFE.

[0003] In practice, PTFE micropowder is often used to lubricate tribological systems with high requirements in terms of energy efficiency, even at low or high temperatures, e.g. in the automotive sector, as it allows very low friction levels to be achieved.

[0004] Since PTFE micropowders also have a very high temperature resistance, they are often used as thickeners or additives in the lubrication of tribological systems with a high upper service temperature, for example at operating temperatures above 160°C and no continuous relubrication option. The use of per- or polyfluorinated products, such as polyfluorinated polyethers or fluorinated silicone oils as base oils is also common. PTFE micropowders are also often used in applications involving contact with food or drinking water due to their low toxicological effects due to their chemical inertness. Food-grade lubricants are generally subject to legal regulations, such as "H1" or "H2" certification (e.g. NSF / H1 or NSF / H2).The "H1" classification is for lubricants that are in "incidental food contact," meaning occasional, technically unavoidable contact with food. However, intentional or continuous contact must be excluded even when using "H1" lubricants. An "H2" classification can be achieved by lubricants that are non-toxic and non-carcinogenic. However, when using "H2" lubricants, any contact with food must be excluded.

[0005] When used, the PTFE powder can be used both as a thickener and as an additive in consistent lubricants.

[0006] PTFE is known for its excellent lubricating properties due to very low and consistent friction coefficients even under high loads. It can effectively prevent stick-slip and demonstrates good stability even when used under high shear stress. Furthermore, it is highly chemically inert towards oxygen. This prevents the oxidation-related deposits frequently occurring in lubricating greases caused by the reaction of the thickener with atmospheric oxygen, thus achieving a consistent and long-lasting lubricating effect. Furthermore, the highly favorable toxicological properties, due to PTFE's good chemical and thermal resistance, ensure a high degree of safety in lubricant operation, and it can even be used in applications with unavoidable food contact. A disadvantage of using per- or polyfluorinated products is that they are problematic from an environmental perspective.

[0007] The object of the present invention is to provide a lubricating grease that has low friction coefficients, particularly good antiwear (AW) and extreme pressure (EP) properties, for use in the lubrication of tribological systems with high energy efficiency requirements over a wide temperature range, e.g., in the automotive sector. Furthermore, it should be possible to manufacture it to H1, preferably NSF / H1, compliant, particularly for drinking water applications. Furthermore, the lubricating grease should be able to dispense with the use of PTFE as a thickener or additive.

[0008] This task is solved by a lubricating grease comprising

[0009] - from 30 wt% to 60 wt% silicone oil,

[0010] - from 10 wt% to 35 wt% polyalphaolefin,

[0011] - from 10 wt% to 45 wt% overbased calcium sulfonate thickener, the amounts being based on the total weight of the lubricating grease.

[0012] Surprisingly, it was found that the lubricating grease according to the invention eliminates the need for PTFE as a thickener or additive, while still exhibiting very low friction values ​​combined with good antiwear (AW) and extreme pressure (EP) properties. Thus, the lubricating grease can also be used to lubricate tribological systems with high energy efficiency requirements, e.g., in the automotive sector, and across a wide temperature range. Furthermore, the lubricating grease can be manufactured to meet H1, preferably NSF / H1, standards and can also be used for drinking water applications. Furthermore, it was surprising that the lubricating grease according to the invention exhibits very good antiwear (AW) and extreme pressure (EP) properties despite its relatively high silicone oil content, since silicone oils are not known to exhibit these properties.For this reason, silicone oil is usually thickened or added with special solid lubricants, such as PTFE, to improve its friction properties. The lubricating grease according to the invention, however, does not require the use of PTFE as a thickener or additive.

[0013] It is also known and has been confirmed in practical tests that typical liquid antiwear (AW) and extreme pressure (EP) additives, such as sulfur carriers, amine phosphates, neutral phosphoric acid esters, (organic) carbamates and / or thiophosphates cannot replace PTFE.

[0014] Furthermore, it was found that even typical solid lubricants such as calcium carbonate cannot sufficiently improve the antiwear (AW) and extreme pressure (EP) properties of silicone oil.

[0015] Surprisingly, however, the antiwear (AW) and extreme pressure (EP) properties can be improved by using an overbased calcium sulfonate thickener. Without committing to a specific mechanism, it is suspected that the calcium carbonate contained in the overbased calcium sulfonate thickener, unlike conventional calcium carbonate, can perform the function of separating the friction partners—possibly because it has a micellar structure and is thus very finely distributed.

[0016] The advantage of using polyalphaolefin (PAO) is that the grease exhibits excellent properties at both high and low temperatures. Practical tests have shown that the use of the overbased calcium sulfonate thickener for the inventive grease enables the base oils silicone oil and polyalphaolefin, which are not homogeneously miscible, to be permanently and homogeneously mixed.

[0017] In particular, it was found in practical tests that the overbased calcium sulfonate thickener in the lubricating grease according to the invention shows a performance almost equivalent to that of PTFE.

[0018] In a preferred embodiment of the invention, the lubricating grease therefore contains no polytetrafluoroethylene and / or only contains polytetrafluoroethylene in a proportion of less than 4 wt.%, more preferably less than 2 wt.%, more preferably less than 1 wt.%, more preferably less than 0.5 wt.%, and more preferably less than 0.1 wt.%, each based on the total weight of the lubricating grease. In a particularly preferred embodiment of the invention, the lubricating grease contains no polytetrafluoroethylene.

[0019] The polytetrafluoroethylene content in the lubricating grease is preferably determined based on the fusion enthalpy of PTFE using the standard DIN EN ISO 11357-1, edition 2008.04. The measurement is conveniently carried out as follows: The oil phase of the lubricating grease, including the soluble additive components, is separated from solid, insoluble components (e.g., thickeners, insoluble additives, and / or solid lubricants) by extraction with a suitable solvent, as this increases measurement accuracy. The polytetrafluoroethylene is part of the insoluble components. Depending on the base oil used, suitable solvents include special gasoline 80 / 110, ethanol, and / or methyl perfluorobutyl ether. Special gasoline 80 / 110 is particularly suitable for lubricating greases whose base oil contains PAO, alkylated aromatics, phenyl ethers, esters, silicone oils and polyglycols with no or low content of ethylene oxide and their mixtures.Ethanol is particularly suitable for lubricating greases containing polyglycol base oils with a high ethylene oxide content. Methyl perfluorobutyl ether is particularly suitable for lubricating greases containing perfluoropolyethers as base oils. Greases containing two immiscible oils are preferably subjected to two extractions. Such greases are commonly referred to as hybrid greases. For example, such hybrid greases can contain both perfluoropolyethers and, preferably, esters. Such a hybrid grease is therefore preferably extracted with both 80 / 110 special gasoline and methyl perfluorobutyl ether to separate both oils and the additives soluble therein. The solvent residues are stripped off from the resulting residue. The resulting dried residue is related to the amount of lubricating grease used. This gives the residue content in wt.%.20 mg of the dry residue is weighed into a 25 μl aluminum DSC crucible and heated to 600°C at a heating rate of 10 K / min. The endothermic signal between 300 and 450°C is integrated; the area of ​​the peak (enthalpy sample) is proportional to the amount of PTFE in the residue. For calibration, a pure PTFE micropowder (particle size D50 according to ASTM D4894 = 5 μm, melt flow index at 372°C / 2.16 kg / 2095 mm according to ASTM D1238 = 0.5 g / 10 min) is measured analogously (enthalpy reference). The PTFE content in the lubricating grease is determined using the following equation:

[0020] (Enthalpy sample) / (Enthalpy reference) * Residue content in wt.% = PTFE content in wt.%

[0021] For the purposes of this invention, the term "lubricating grease" is understood in the conventional sense. Lubricating greases are defined as solid to semi-liquid substances that can be produced by dispersing a thickener in a liquid lubricant. In addition to the thickener, lubricating greases can also contain other additives that impart special properties to the grease. Lubricating greases are defined in the standard ASTM D217-21, edition 2021.07.

[0022] In a further preferred embodiment of the invention, the lubricating grease contains no boric acid and no boric acid compounds selected from metal borates and boric acid esters and / or boric acid and boric acid compounds selected from boric acid, metal borates and boric acid esters only in a proportion of less than 2 wt.%, more preferably less than 1 wt.%, based on the total weight of the lubricating grease. The term "proportion of boric acid and boric acid compounds" refers to the combined amounts of boric acid and boric acid compounds potentially present in the lubricating grease. This embodiment is advantageous because boric acid and the aforementioned boric acid compounds are toxicologically undesirable. In a particularly preferred embodiment of the invention, the lubricating grease therefore contains no boric acid and no boric acid compounds selected from boric acid, metal borates and boric acid esters.

[0023] Metal borates are boron compounds that can be obtained by chemically reacting boric acid with inorganic bases. Boric acid esters are boron compounds that can be obtained by chemically reacting boric acid with organic alcohols.

[0024] According to the invention, the lubricating grease contains from 30 wt.% to 60 wt.%, preferably from 33 wt.% to 57 wt.%, even more preferably from 35 wt.% to 55 wt.%, in particular from 40 wt.% to 55 wt.% silicone oil, in each case based on the total weight of the lubricating grease. The silicone oil is preferably a fluorine-free silicone oil, i.e., it has no fluorine atoms in its structural formula. The silicone oil preferably contains alkylated silicone oil, arylated silicone oil, and / or alkylaryl silicone oil. The silicone oil particularly preferably contains alkylated silicone oil, preferably C1-5 alkylated silicone oil, for example methylated silicone oil, in particular dimethyl silicone oil and / or phenylmethyl silicone oil. Particularly preferably, the lubricating grease contains from 30 wt.% to 60 wt.%, preferably from 33 wt.% to 57 wt.%, even more preferably from 35 wt.% to 55 wt.%, in particular from 40 wt.% to 55 wt.% dimethyl silicone oil, in each case based on the total weight of the lubricating grease.

[0025] The silicone oil may also be a mixture of silicone oils with different chemical compositions and / or different kinematic viscosities.

[0026] The silicone oil, preferably the dimethyl silicone oil and / or phenylmethyl silicone oil, preferably has a kinematic viscosity at 25°C of 550 mm 2 / s up to 15,000 mm 2 / s, more preferably 700 mm 2 / s up to 10,000 mm 2 / s, more preferably 800 mm 2 / s up to 8 000 mm 2 / s, measured according to DIN EN 16896 - 2017-02. The silicone oil preferably also has a kinematic viscosity at 40°C of 500 mm 2 / s up to 10,000 mm 2 / s, more preferably 1000 mm 2 / s up to 6000 mm 2 / s, measured according to DIN EN 16896 - 2017-02. These viscosities are particularly suitable for tribological systems that come into contact with food and / or drinking water.

[0027] In a further preferred embodiment, the silicone oil has a kinematic viscosity at 25°C of 10 mm 2 / s up to 1,000,000 mm 2 / s, more preferably 50 mm 2 / s up to 100,000 mm 2 / s, more preferably 100 mm 2 / s up to 25,000 mm 2 / s, measured according to DIN EN 16896 - 2017-02. The silicone oil preferably also has a kinematic viscosity at 40°C of 500 mm 2 / s up to 10,000 mm 2 / s, more preferably 1000 mm 2 / s up to 6000 mm 2 / s, measured according to DIN EN 16896 - 2017-02. These viscosities are particularly suitable for lubricating joints and actuators in automobiles.

[0028] In addition to the polyalphaolefin and silicone oil, the lubricant composition may contain other base oils. Particularly preferred base oils are H1, preferably NSF / H1-compliant base oils. Also preferred base oils are base oils that can be approved for occasional contact with food, particularly according to EN ISO 21469 (February 2006), Appendix B. Approval should preferably be granted by the National Sanitation Foundation, USA (NSF).

[0029] A base oil is understood to mean the base fluids commonly used for the manufacture of lubricants, in particular oils that can be assigned to groups I, II, II+, III, IV or V according to the classification of the American Petroleum Institute (API) [NLGI Spokesman, N. Samman, Volume 70, Number 11 , p.14ff].Particularly preferred further base oils are selected from the group consisting of esters, ethers, in particular polyethers, phenyl ethers, perfluoropolyethers, mineral oils, white oils, synthetic hydrocarbons which do not belong to the class of polyalphaolefins, in particular alkylated naphthalenes, copolymers of unsaturated hydrocarbons, for example polymers of ethylene and alphaolefins (for example Lucant HC-600®), natural hydrocarbons, native oils and derivatives of native oils and mixtures thereof, wherein for these further base oils an approval for occasional contact with food is preferably possible, in particular in accordance with EN ISO 21469 (February 2006) Appendix B. The approval should preferably be able to be carried out by the National Sanitation Foundation, USA (NSF).Particularly preferred further base oils according to the invention are esters, ethers, preferably polyethers, diphenyl ethers, polyphenyl ethers, synthetic hydrocarbons which do not belong to the class of polyalphaolefins, alkylated naphthalenes, white oils, copolymers of unsaturated hydrocarbons and / or mixtures thereof, wherein for these further base oils, approval for occasional contact with food is preferably possible, in particular according to EN ISO 21469 (February 2006) Appendix B. The approval should preferably be able to be granted by the National Sanitation Foundation, USA (NSF).Ethers, preferably polyalkylene glycols, in particular polypropylene glycol homopolymers and / or copolymers with ethyl groups and 1-methylethyl groups as carbon groups in the repeating unit are particularly preferred, with these additional base oils preferably being approved for occasional contact with food, in particular in accordance with EN ISO 21469 (February 2006), Annex B. Approval should preferably be granted by the National Sanitation Foundation, USA (NSF).

[0030] In a particularly preferred embodiment of the invention, the additional base oil is selected from the group consisting of esters, ethers, preferably polyethers, synthetic hydrocarbons which do not belong to the class of polyalphaolefins, white oils, perfluoropolyethers, alkylated naphthalenes and mixtures thereof, wherein for these additional base oils, approval for occasional contact with food is preferably possible, in particular according to EN ISO 21469 (February 2006) Annex B. The approval should preferably be able to be carried out by the National Sanitation Foundation, USA (NSF).

[0031] Other preferred base oils are polyethers. Polyethers are polymers whose organic repeating units are formed from ether functionalities (CO-C). In the subgroup of polyphenyl ethers, the carbon portion of the repeating unit consists of phenyl groups. In the subgroup of polyalkylene glycols, the carbon portion of the repeating unit consists of substituted or unsubstituted ethyl groups (OCCO), such as ethyl groups, 1-methylethyl groups, or 1-ethylethyl groups. Such polyalkylene glycol homopolymers are typically also referred to as polyethylene glycol, polypropylene glycol, and polybutylene glycol. Polyalkylene glycols also refer to polymers that contain mixtures of variously substituted ethyl groups, such as ethyl groups, 1-methylethyl groups, or 1-ethylethyl groups, as carbon portions of the repeating unit.These polyalkylene glycols can be present both as block polymers and as polymers with a random distribution of carbon groups. Other preferred polyethers are polytetrahydrofurans and oxetane polymers, which have four (OCCCCO) or three carbon atoms (OCCCO) in the carbon portion of the repeat unit, respectively.

[0032] Preferred polyethers are polyalkylene glycols. Particularly preferred polyalkylene glycols are polypropylene glycol homopolymers and / or copolymers with ethyl groups and 1-methylethyl groups as carbon groups in the repeating unit.

[0033] The end groups of the polyalkylene glycols, polytetrahydrofurans and oxetane polymers are, independently of one another, preferably hydroxide groups and / or alkoxide groups, where the alkyl portion of the alkoxide groups can be formed from C1 to C20 alkyl groups. The end groups of the polyalkylene groups can additionally be substituted. The end group can be introduced during the preparation of the polyalkylene glycols, polytetrahydrofurans and oxetane polymers by reacting the monomeric ethylene oxides, tetrahydrofurans or oxetanes with a monofunctional starter. Monofunctional starters are preferably alcohols, in particular butanol. Two or more chains of polyalkylene glycols, polytetrahydrofurans and oxetane polymers can also be linked via an end group. Alkyl groups are preferred as the linking end group. This can occur during the preparation of the polyalkylene glycols, polytetrahydrofurans and oxetane polymers from ethylene oxides, tetrahydrofurans orOxetanes can be prepared with a nucleophilic di- or higher-functional starter. Examples of difunctional starters are diols, especially 1,2-ethanediol.

[0034] Very particularly preferred polyethers are polyalkylene glycols, even more preferably polypropylene glycol homopolymers and / or copolymers with ethyl groups and 1-methylethyl groups as carbon groups in the repeating unit. The aforementioned polyalkylene glycols are also particularly preferred when butanol or 1,2-ethanediol are used as starters. The aforementioned polyalkylene glycols are also particularly preferred when they have a butyl group as the end group and / or are linked via an ethylene group.

[0035] Preferred esters are carboxylic acid esters, preferably monoesters, diesters, triesters, tetraesters, pentaesters, polyesters, estolides, and mixtures thereof. Diesters, triesters, tetraesters, pentaesters, polyesters, estolides, and mixtures thereof are particularly preferred. Estolides are especially preferred, as they can be particularly suitable for food-grade lubricants.

[0036] Likewise preferred esters are aromatic esters, preferably of aromatic di-, tri-, or tetracarboxylic acids with one or a mixture of C7 to C22 alcohols, and aliphatic esters, preferably of monocarboxylic acids and / or dicarboxylic acids with a mono-, di-, tri-, tetra, penta, or hexa-alcohol having a carbon number of 3 to 22, present individually or in mixtures, polyol esters, such as preferably complex esters, estolides, and mixtures thereof, these esters preferably being suitable for H1, preferably NSF / H1. The acid and / or alcohol component of the carboxylic acid esters, independently of one another, preferably has a number of carbon atoms from C3 to C54.

[0037] Estolides are oligomers of aliphatic hydroxycarboxylic acids, preferably of 12-hydroxystearic acid or oligomers of unsaturated carboxylic acids, preferably of oleic acid, in which the terminal carboxylic acid group is esterified with a mono-alcohol, dialcohol, trialcohol and / or tetraalcohol, preferably branched monoalcohols, very particularly preferably Guerbet alcohols, and in which any free hydroxide groups may be esterified by reaction with monocarboxylic acids or dicarboxylic acids.

[0038] Particularly preferred are aliphatic esters of monocarboxylic acids and / or dicarboxylic acids having a carbon number of C3 to C40 with a mono-, di-, tri-, tetra, penta, hexa-alcohol having a carbon number of 3 to 22, present individually or in mixtures.

[0039] Even more preferred are aliphatic esters of monocarboxylic acids and / or dicarboxylic acids having a carbon number of C3 to C40 with a mono-, tri-, tetra, hexa-alcohol having a carbon number of 3 to 22, present individually or in mixtures.

[0040] Even more preferred are aliphatic esters of monocarboxylic acids having a carbon number of C5 to C22 with a tri, tetra, hexa-alcohol having a carbon number of C3 to C10, present individually or in mixtures, in particular trimethylolpropane, pentaerythritol and / or dipentaerythritol, and / or of dicarboxylic acids having a carbon number of C6 to C40, in particular C18 dimer acids, with a mono- and / or dialcohol having a carbon number of 6 to 22, present individually or in mixtures. Very particular preference is given to esters of trimethylolpropane, pentaerythritol and / or dipentaerythritol with aliphatic C7 to C22 carboxylic acids and / or esters of C18 dimer acids with C7 to C22 alcohols. Esters which can be approved for occasional contact with food, in particular according to EN ISO 21469 (February 2006) Annex B, are particularly preferred.The approval should preferably be granted by the National Sanitation Foundation, USA (NSF).

[0041] Preferably, the proportion of the further base oil in the lubricant composition, if present, is from 5 to 25 wt.%, more preferably from 10 to 25 wt.%, in particular from 12 to 20 wt.%, in each case based on the total weight of the lubricating grease.

[0042] According to the invention, the lubricating grease contains from 10 wt.% to 35 wt.%, preferably from 12 wt.% to 32 wt.%, in particular from 15 wt.% to 30 wt.%, of polyalphaolefin (PAO), based in each case on the total weight of the lubricating grease. An advantage of polyalphaolefin (PAO) is its good low-temperature behavior. Furthermore, it contains no MOSH-MOAH components. In a particularly preferred embodiment, it is suitable for applications in which the lubricating grease is in occasional, technically unavoidable contact with food (H1, preferably NSF / H1 compatible). In a particularly preferred embodiment, the PAO meets the requirements of EN ISO 21469 (February 2006).

[0043] The polyalphaolefin preferably further has a kinematic viscosity at 40°C of 18 mm 2 / s up to 400 mm 2 / s, more preferably 18 mm 2 / s up to 100 mm 2 / s, especially 25 mm 2 / s up to 65 mm 2 / s, more preferably 27 mm 2 / s up to 65 mm 2 / s, measured according to DIN EN 16896 - 2017-02. The polyalphaolefin can also be a mixture of polyalphaolefins with different chemical structures and / or different kinematic viscosities.

[0044] The polyalphaolefin can be acid-catalyzed polyalphaolefin or metallocene-catalyzed polyalphaolefin.

[0045] Preferably, the polyalphaolefin is acid-catalyzed polyalphaolefin.

[0046] According to the invention, the lubricating grease contains from 10 wt.% to 45 wt.%, preferably from 15 wt.% to 43 wt.%, more preferably from 15 wt.% to 41 wt.%, even more preferably from 15 wt.% to 36 wt.%, in particular from 16 wt.% to 33 wt.% of overbased calcium sulfonate thickener based on the total weight of the lubricating grease.

[0047] Overbased calcium sulfonate thickeners are well-known thickeners. They are described, for example, in Lubricants and Lubrication, 2005, Wiley-VCH Verlage GmbH Co. KGaA, Weinheim, p. 141, and in US Pat. No.

[0048] 3,242,079; 3,372,115; 3,376,222; 3,377,283; and 3,492,231. Wayne Mackwood, Tribology & Lubrication Technology, Oct. 28, 2016, pp. 26-40, "Calcium sulfonate complex greases," provides an overview of calcium sulfonate greases. Among other things, it is described that the particle size of the calcite crystals is typically between 100 nm and 400 nm. The particle size of the amorphous calcium carbonate is typically less than 50 nm.

[0049] Overbased calcium sulfonate thickeners, when combined with base oils such as silicone oil and / or PAO, are assumed to form a micellar structure. The core of the micelle is formed by calcium carbonate with a portion of crystalline calcium carbonate. Sulfonate and carboxylate anions accumulate on the surface of the calcium carbonate core.

[0050] According to the invention, the overbased

[0051] Calcium sulfonate thickeners in the lubricating grease are present in a micellar structure.

[0052] The overbased calcium sulfonate thickener therefore preferably contains calcium sulfonate, calcium carbonate with a proportion of crystalline calcium carbonate, and calcium carboxylate. In addition to the crystalline calcium carbonate, the calcium carbonate may also contain amorphous calcium carbonate.

[0053] To calculate the proportion of overbased calcium sulfonate thickener in the lubricating grease, the sum of the proportions of calcium sulfonate, calcium carbonate with a proportion of crystalline calcium carbonate, and calcium carboxylate is determined according to the invention and related to the total weight of the lubricating grease. Thus, the total proportion of calcium carbonate in the lubricating grease is taken. Preferably, the proportion of crystalline calcium carbonate based on the total amount of calcium carbonate is more than 90 wt.%, particularly preferably more than 95 wt.%, and especially approximately 100 wt.%.

[0054] More preferably, the proportion of crystalline calcium carbonate based on the total amount of overbased calcium sulfonate thickener is 25 to 50 wt.%.

[0055] A preferred process according to the invention for producing calcium sulfonate thickeners is a two-step process comprising the steps of "promotion" and "conversion." Typically, the first step ("promotion") involves reacting a stoichiometric excess of calcium oxide (CaO) or calcium hydroxide (Ca(OH)2) as the base source with an alkylbenzenesulfonic acid, carbon dioxide (CO2), and other acids to obtain an oil-soluble overbased calcium sulfonate with amorphous calcium carbonate dispersed therein. This reaction can be carried out in a suitable base oil, for example, silicone oil and / or PAO. This overbased calcium sulfonate is not yet considered a calcium sulfonate thickener, but is a liquid, usually a Newtonian liquid. The overbased calcium sulfonate can be introduced into a suitable base oil, for example, silicone oil and / or PAO.

[0056] The second step ("conversion") typically consists of adding one or more conversion agents, such as propylene glycol, isopropyl alcohol, water, fatty acid, formic acid, or acetic acid, to the product of the promotion step, and optionally a suitable base oil, for example, the silicone oil and / or PAO contained in the lubricating grease according to the invention, if necessary to prevent the reaction mixture from becoming too hard, to convert the amorphous calcium carbonate contained in the overbased calcium sulfonate into a very finely divided dispersion of crystalline calcium carbonate (calcite). When acetic acid or other acids are used as conversion agents, water and another non-aqueous conversion agent (a third conversion agent, e.g., an alcohol) are typically also used; alternatively, only water (without the third conversion agent) is added, but the conversion then usually takes place in a pressure vessel.Since an excess of calcium hydroxide or calcium oxide is used to achieve overbasing, a small amount of residual calcium oxide or calcium hydroxide may also be present as part of the oil-soluble superfatted calcium sulfonate and becomes dispersed in the original fatty structure. The extremely finely divided calcium carbonate formed by the conversion, also called a colloidal dispersion, interacts with the calcium sulfonate to form a fat-like consistency, thus forming the overbased calcium sulfonate thickener. Neutral conversion agents such as water and alcohols can act as swelling agents in the micelle core. Such overbased calcium sulfonate thickeners prepared by the two-step process are disclosed, for example, in U.S. Pat. Nos. 3,242,079; 3,372,115; 3,376,222; 3,377,283; and 3,492,231.

[0057] It is also possible to combine these two steps into a single step. In this one-step process, the overbased calcium sulfonate thickener is produced by reacting a suitable sulfonic acid with either calcium hydroxide or calcium oxide in the presence of carbon dioxide and a system of reagents that simultaneously act as both a promoter (generating the amorphous calcium carbonate overbased product by reacting carbon dioxide with an excess amount of calcium oxide or calcium hydroxide) and a converting agent (converting the amorphous calcium carbonate into very finely divided crystalline calcium carbonate). In this way, the fat-like consistency is formed in a single step, with the overbased, oil-soluble calcium sulfonate (the product of the first step of the two-step process, not yet a thickener) never actually being formed and being isolated as a separate product.This one-step process is disclosed, for example, in U.S. Patent Nos. 3,661,622, 3,671,012, 3,746,643 and 3,816,310.

[0058] In a preferred embodiment of the invention, the overbased calcium sulfonate thickener is prepared by a process comprising treating an overbased calcium sulfonate with one or more converting agents, preferably propylene glycol, isopropyl alcohol, water, fatty acid, formic acid, and / or acetic acid, to obtain the overbased calcium sulfonate thickener. Overbased calcium sulfonate contains an excess of calcium carbonate and / or calcium hydroxide. Preferred embodiments of the process include those described above and below.

[0059] The calcium sulfonate thickener preferably has a primary particle size, measured according to DIN Spec 52407: 2015 DE, of 100 nm to 250 nm, more preferably of 120 nm to 200 nm.

[0060] The overbased calcium sulfonate thickener preferably contains calcium sulfonate. It is assumed that in the lubricating grease, the calcium sulfonate of the overbased calcium sulfonate thickener is oriented with respect to the base oil such that the polar part is oriented toward calcium carbonate particles and the non-polar part is oriented toward the oil phase. The term calcium sulfonate is intended to encompass a single calcium sulfonate compound or mixtures of different calcium sulfonate compounds. The calcium sulfonate preferably comprises mixtures of different calcium sulfonate compounds. For the sake of simplicity, the term calcium sulfonate is used below in the description of preferred embodiments; however, as explained above, it is also intended to encompass mixtures of different calcium sulfonate compounds.

[0061] The calcium sulfonate can contain a natural sulfonate derived from petroleum fractions, a synthetic sulfonate derived from the alkylation of aromatic compounds, or mixtures of natural or synthetic sulfonates. Synthetic sulfonates include alkylsulfonates and alkylarylsulfonates. The calcium sulfonate preferably contains alkylarylsulfonates, more preferably alkylbenzylsulfonates, and especially dialkylbenzylsulfonates, preferably dialkylbenzylsulfonates in combination with monoalkylbenzylsulfonates. In the alkylbenzylsulfonates, the alkyl is preferably formed as one or more side chains attached as substituents to the benzyl position of the benzyl ring. More preferably, each side chain independently has 1 to 25 carbon atoms, preferably 1 to 19 carbon atoms. The side chains can be straight-chain or branched-chain. Straight-chain side chains are preferred.More preferably, the calcium sulfonate comprises at least two structurally different alkylbenzylsulfonates.

[0062] In a particularly preferred embodiment, the calcium sulfonate contains a calcium salt of an alkylbenzylsulfonic acid of the following formula where the radicals R1 and R2 are independently selected from hydrogen, C1-C25, preferably C1-C19 alkyl, with the proviso that R1 and R2 are not simultaneously hydrogen. R1 is preferably selected from hydrogen, C1-C4 alkyl, and R2 is selected from C7-C19 alkyl. Very particularly preferably, R1 is selected from hydrogen, C1-C4 alkyl, and R2 is selected from C10-C19 alkyl. The radicals R1 and R2 are preferably unbranched. More preferably, the radical C(R1 R2) is in the para-position to the sulfonic acid radical. The alkylbenzylsulfonic acid preferably contains a mixture of structurally different alkylbenzenesulfonic acids. The alkylbenzylsulfonic acid preferably contains a mixture of alkylbenzenesulfonic acids that differ in the chain length of their alkyl substituents.

[0063] In a further particularly preferred embodiment, the calcium sulfonate contains a calcium salt of an alkylbenzylsulfonic acid of the following formula where R1 is selected from C1-C4 alkyl, preferably C2-C4 alkyl and especially C3 alkyl, and R2 is selected from C4-C19 alkyl, preferably C8-C19 alkyl, more preferably C8-C19 alkyl and especially C9-C19 alkyl. Preferably, the C(R1 R2) radical is in the para-position to the sulfonic acid radical. Further preferably, the R1 and R2 radicals are unbranched.

[0064] More preferably, the calcium sulfonate contains a calcium salt of an alkylbenzylsulfonic acid of the formula where R1 is selected from hydrogen and R2 is selected from C3-C25 alkyl, preferably C5-C19 alkyl, more preferably C7-C19 alkyl and especially C10-C19 alkyl. Preferably, the radicals R1 and R2 are unbranched. The calcium salt preferably represents a mixture that can be obtained from structurally different alkylbenzenesulfonic acids. Preferably, the radical C(R1 R2) is in the para-position to the sulfonic acid radical. Further preferably, the radicals R1 and R2 are unbranched. In a very particularly preferred embodiment, the calcium sulfonate contains a calcium salt of an alkylbenzylsulfonic acid of the following formula

[0065] wherein R1 is selected from C1-C4 alkyl, preferably C2-C4 alkyl and in particular C3 alkyl and R2 is selected from C4-C19 alkyl, preferably Cs-C19 alkyl, more preferably C8-C19 alkyl and in particular C9-C19 alkyl in combination with a calcium salt of an alkylbenzylsulfonic acid of the formula where R1 is selected from hydrogen and R2 is selected from C3-C25

[0066] Alkyl, preferably C5-C19 alkyl, more preferably C7-C19 alkyl, and especially C10-C19 alkyl. The C(R1 R2) radical is preferably in the para-position to the sulfonic acid radical. Likewise, the R1 and R2 radicals are preferably unbranched.

[0067] The calcium sulfonate is preferably a mixture that can be obtained from structurally different alkylbenzenesulfonic acids. The alkyl substituent is also preferably located para to the sulfonic acid residue.

[0068] In a particularly preferred embodiment of the invention, the overbased calcium sulfonate thickener contains calcium dodecylsulfonate. More preferably, the overbased calcium sulfonate thickener contains calcium octadecylsulfonate. Most preferably, the overbased calcium sulfonate thickener contains calcium dodecylsulfonate in combination with calcium octadecylsulfonate.

[0069] The calcium sulfonate thickener preferably further contains calcium carboxylate. The term "calcium carboxylate" is intended to encompass a single calcium carboxylate compound or mixtures of various calcium carboxylate compounds. For the sake of simplicity, the term "calcium carboxylate" is used below in the description of preferred embodiments, although, as explained above, it is also intended to encompass mixtures of various calcium carboxylate compounds.

[0070] In a preferred embodiment of the invention, the calcium carboxylate comprises a C1-C20 alkyl carboxylate. Preferably, the calcium carboxylate comprises a combination of calcium acetate and / or calcium propionate with calcium stearate. Particularly preferably, the calcium carboxylate comprises calcium acetate in combination with calcium stearate, preferably calcium acetate in combination with calcium hydroxystearate, in particular calcium acetate in combination with calcium 12-hydroxystearate. The calcium sulfonate thickener preferably further contains calcium carbonate with a proportion of crystalline calcium carbonate.

[0071] In a preferred embodiment, the crystalline calcium carbonate contains calcium carbonate with a calcite crystal structure. The advantage of a calcite structure is that calcite forms a layered structure, which leads to particularly good separation of the friction partners and low friction values. The crystalline calcium carbonate can also contain calcium carbonate with a vaterite and / or calcium carbonate with an aragonite structure.

[0072] In a preferred embodiment, the overbased calcium sulfonate thickener is present at least partially in the form of micelles. Micelles are aggregated molecular complexes (aggregates) of amphiphilic molecules. This is advantageous because the thickener components are very finely distributed and can therefore particularly effectively perform the function of separating the friction partners.

[0073] In a preferred embodiment of the invention, the lubricating grease contains 1 wt.% to 20 wt.%, preferably from 3 wt.% to 15 wt.%, even more preferably from 4 wt.% to 11 wt.%, each based on the total weight of the lubricating grease, of co-thickener. The co-thickener is preferably selected from bentonite, lithium soap, in particular Li-12-hydroxystearate, boron nitride, talc, and / or pyrogenic silicon dioxide.Likewise suitable co-thickeners are selected from inorganic phosphate, in particular tricalcium phosphate, IIHMWPE (Ultra High Molecular Weight Polyethylene), layered silicate, in particular mica, inorganic pyrophosphate, in particular dicalcium pyrophosphate, inorganic sulfide, in particular zinc sulfide, lithium carboxylate, calcium carbonate with a d50, measured by laser diffraction, evaluation with Mie theory (ISO 13320:2020-1) of 1 pm to 20 pm, preferably from 1 pm to 10 pm, multi-component inorganic hydroxides, in particular aluminum magnesium carbonate hydroxide, aluminum magnesium carbonate hydroxide hydrate, aluminum magnesium zinc carbonate hydroxide and / or aluminum magnesium zinc carbonate hydroxide hydrate, hydrotalcite and / or kaolin.

[0074] Preferred kaolin is kaolin with a d50, measured by laser diffraction, evaluation with Mie theory (ISO 13320:2020-1 ) of 0.05 pm to 10 pm, more preferably from 0.05 pm to 6 pm, in particular from 0.05 pm to 1 pm.

[0075] Preferred hydrotalcite is hydrotalcite with a d50, measured by laser diffraction, evaluation with Mie theory (ISO 13320:2020-1 ) of 0.01 pm to 10 pm, more preferably from 0.01 pm to 6 pm, in particular from 0.01 pm to 2 pm.

[0076] Likewise suitable co-thickeners are selected from bentonite, lithium carboxylate, preferably lithium soap, in particular Li-12-hydroxystearate, calcium carbonate with a d50, measured by laser diffractometry, evaluation with Mie theory (ISO 13320:2020-1) of 1 pm to 20 pm, preferably from 1 pm to 10 pm, boron nitride, layered silicate, in particular mica and / or talc, pyrogenic silicon dioxide, inorganic phosphate, in particular tricalcium phosphate, UHMWPE (Ultra High Molecular Weight Polyethylene), inorganic pyrophosphate, in particular dicalcium pyrophosphate, inorganic sulfide, in particular zinc sulfide, multicomponent inorganic hydroxides, in particular aluminum magnesium carbonate hydroxide, aluminum magnesium carbonate hydroxide hydrate, Aluminum magnesium zinc carbonate hydroxide and / or aluminum magnesium zinc carbonate hydroxide hydrate, hydrotalcite and / or kaolin.In a preferred embodiment, the lubricating grease contains at least one co-thickener selected from the group consisting of inorganic phosphate, in particular tricalcium phosphate, calcium carbonate with a d50, measured by laser diffraction, evaluation with Mie theory (ISO 13320:2020-1) of 1 pm to 20 pm, preferably from 1 pm to 10 pm, hydrotalcite, pyrogenic silicon dioxide, lithium carboxylate, preferably lithium soap, in particular Li-12-hydroxystearate, kaolin, and mixtures thereof.

[0077] In a particularly preferred embodiment, the lubricating grease contains at least two different, preferably at least three different, in particular at least four different, co-thickeners selected from the group consisting of inorganic phosphate, in particular tricalcium phosphate, calcium carbonate with a d50, measured by laser diffraction, evaluation with Mie theory (ISO 13320:2020-1) of 1 pm to 20 pm, preferably of 1 pm to 10 pm, hydrotalcite, pyrogenic silicon dioxide, lithium carboxylate, preferably lithium soap, in particular Li-12-hydroxystearate, kaolin.

[0078] In a very particularly preferred embodiment, the lubricating grease contains as co-thickener calcium carbonate with a d50, measured by laser diffraction, evaluation with Mie theory (ISO 13320:2020-1) of 1 pm to 20 pm, preferably from 1 pm to 10 pm, pyrogenic silicon dioxide, lithium carboxylate, preferably lithium soap, in particular Li-12-hydroxystearate and additionally as further co-thickener kaolin or hydrotalcite and optionally inorganic phosphate, in particular tricalcium phosphate.

[0079] More preferably, the lubricating grease contains 1 wt.% to 20 wt.%, preferably from 3 wt.% to 15 wt.%, even more preferably from 4 wt.% to 11 wt.%, in each case based on the total weight of the lubricating grease, of bentonite and / or fumed silica as a co-thickener. The co-thickener preferably contains bentonite and fumed silica, particularly preferably in a ratio of bentonite to fumed silica of 30 wt.% : 70 wt.% to 70 wt.% : 30 wt.%. Preferred fumed silica is fumed silica functionalized with organic groups. The bentonite preferably has a particle size, measured by laser diffraction, evaluation with Mie theory (ISO 13320:2020-1), of 2 to 15 pm.

[0080] Suitable fumed silica is described, for example, in the technical journal "Technical Overview: Aerosil-Pyrogenic Silica" by Evonic Industries 03-2017. This journal also describes suitable fumed silica functionalized with organic groups.

[0081] In a particularly preferred embodiment, the fumed silica is fumed silica functionalized with organic groups. The functionalized fumed silica particularly preferably has a BET surface area, measured according to ISO 9277 2014 01, of 10 to 500 m 2 / g, more preferably from 50 to 400 m 2 / g, especially from 50 to 200 m 2 / g. More preferably, the functionalized pyrogenic silicon dioxide has a primary particle size, measured by transmission electron microscopy, of 5 to 50 nm. More preferably, the functionalized pyrogenic silicon dioxide has a tapped density, measured according to ISO787 / 11 1995, of 50 g / l to 280 g / l, even more preferably of 50 g / l to 200 g / l. More preferably, the functionalized pyrogenic silicon dioxide has a carbon content, measured according to ISO-3262-202021, of 0.5 wt.% to 8.8 wt.%, preferably of 0.5 wt.% to 6 wt.%, in particular of 0.5 wt.% to 2 wt.%.

[0082] Preferred organic groups are branched or unbranched aliphatic and / or aromatic groups, preferably with 1 to 20 carbon atoms. Preferred aromatic groups have 6 to 10 carbon atoms. Preferred aliphatic groups have 1 to 10 carbon atoms. Particularly preferred organic groups are methyl, ethyl, propyl, vinyl, butyl, pentyl, hexyl, heptyl, octyl, and / or phenyl. Methyl groups are particularly preferred organic groups. Another advantage of using these materials is their friction level, which is comparable to PTFE even under high tribological loads, and the fact that they enable lubrication concepts with significantly lower shear viscosities compared to PTFE products.

[0083] The lubricating grease according to the invention may further contain from 0.1 to 5 wt.% of additives, which are used individually or in combination and are selected from the group consisting of corrosion protection additives, antioxidants, wear protection additives, UV stabilizers and mixtures thereof.

[0084] In order to comply with legal regulations regarding the use of lubricants for lubricating equipment for food processing, it is advisable for the additives used to have an H1 classification.

[0085] The addition of antioxidants can reduce or even prevent oxidation of the lubricating grease according to the invention, especially during its use. Oxidation can generate undesirable free radicals, resulting in increased decomposition reactions in the grease. The addition of antioxidants can stabilize the grease.

[0086] Antioxidants particularly suitable according to the invention are the following food-compatible compounds: diaromatic amines, phenolic resins, thiophenol resins, phosphites, butylated hydroxytoluene, butylated hydroxyanisole, phenyl-alpha-naphthylamine, phenyl-beta-naphthylamine, octylated / butylated diphenylamine, di-alpha-tocopherol, di-tert-butyl-phenyl, benzenepropanoic acid and mixtures of these components.

[0087] Commercially available food-grade additives include:

[0088] IRGANOX® 1010 (benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-

[0089] 2.2-bis[[3-[3, 5-bis( 1 , 1 -dimethylethyl)-4-hydroxyphenyl]-1 -oxopropoxy]methyl]-

[0090] 1,3-propanediyl ester; IRGANOX® L06 (alkylated phenyl-alpha-naphthylamine or N-phenyl-ar-(1,1,3,3-tetramethylbutyl)-1-naphthalenamine;

[0091] IRGANOX® L01 (dioctylated diphenylamine);

[0092] IRGANOX® L57 (mixture of alkylated diphenylamines);

[0093] IRGANOX® L06;

[0094] IRGANOX® L 115;

[0095] IRGANOX® L150 (mixture of high molecular weight amine and phenolic antioxidants);

[0096] IRGANOX® L64 (mixture of mono- and dialkyl butyl / octyl-diphenylamine);

[0097] IRGANOX® 1035; (mixture consisting of thiodiethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate);

[0098] IRGANOX® 1010;

[0099] IRGANOX® L101 (mixture consisting of tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane);

[0100] IRGANOX® L109 (benzenepropanoic acid, 3,5-bis(1,1-dimethyl)-4-hydroxy-1,6-

[0101] hexanediyl ester);

[0102] IRGANOX® L57;

[0103] IRGANOX® L109;

[0104] Irgalube® TPPT;

[0105] IRGANOX® L115 (benzenepropionic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, thiodi-2,1-ethanediyl ester); IRGANOX® E201 (liquid DL-alpha-tocopherol, 2H-1-benzopyran-6-ol,3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl);

[0106] IRGAFOS® 168 (mixture containing tris(2,4-di-tert-butylphenyl)phosphate);

[0107] ADDITIN® RC7130 (N-phenyl-1-naphthylamine);

[0108] Na-LUBE® A0142 (liquid diphenylamine-based antioxidant);

[0109] VANLUBE® 961 (mixture of octylated and butylated diphenylamine or benzeneamine, N-phenyl, reaction product of 2, 4-trimethylpentane and 2-methylpropene);

[0110] VANLUBE® PCX (mixture containing 1-hydroxy-4-methyl-2,6-di-tert-butylbenzene); hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide); Irgafox® 168; reaction product of N-phenylbenzenamine with 2,4,4-trimethylpentene;

[0111] Thiodiethylenbis(3,5-di-tert-butyl-4-hydroxyhydro-Cinnamatmethan); Bis(4-(1 ,1 ,3,3-tetramethylbutyl)phenyl)amin;

[0112] 3, 5-B is( 1 , 1 -dimethylethyl)-4-hydroxyester;

[0113] Thiodi-2, 1 -Ethandiylester.

[0114] The grease may also contain corrosion inhibitors, metal deactivators, and / or ion complexing agents. These include triazoles, imidazolines, N-methylglycine (sarcosine), benzotriazole derivatives, N,N-bis(2-ethylhexyl)-ar-methyl-1H-benzotriazole-1-methanamine; n-methyl-N(1-oxo-9-octadecenyl)glycine, mixtures of phosphoric acid and mono- and diisooctyl esters reacted with (C11-14)-alkylamines, mixtures of phosphoric acid and mono- and diisooctyl esters reacted with tert-alkylamine and primary (C12-14)-amines, dodecanoic acid, triphenyl phosphorothionate, and amine phosphates, and mixtures. Commercially available additives are the following: IRGAMET® 39, IRGACOR® DSS G, Amin 0; SARKOSYL® 0 (Ciba), COBRATEC® 122, CUVAN® 303, VANLUBE® 9123, CI-426, CI-426EP, CI-429, and CI-498. Other possible wear protection additives include amines, amine phosphates, phosphates, thiophosphates, phosphothionates, and mixtures of these components.Commercially available antiwear 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.

[0115] In a further preferred embodiment of the invention, the lubricating grease is H1, preferably NSF / H1-compliant. In a further preferred embodiment of the invention, the lubricating grease meets the requirements of EN ISO 21469 (February 2006). Thus, the lubricating grease preferably meets the requirements to be achieved by lubricants that are in "incidental food contact," i.e., occasional, technically unavoidable contact with food.

[0116] The lubricating grease is therefore preferably formulated in such a way that approval for occasional contact with food is possible, in particular in accordance with EN ISO 21469 (February 2006) Appendix B. In this case, approval should preferably be possible from the National Sanitation Foundation, USA (NSF). Particularly preferably, the lubricating grease and in particular all raw materials of the lubricating grease are selected in such a way that approval according to H1, preferably NSF-H1, is possible. This enables the lubricating grease according to the invention to be used in applications in which it is in occasional contact with food. This makes it ideally suited, for example, for lubricating tribological systems that come into contact with food and / or drinking water, in particular equipment in food processing and / or for gas and (drinking) water fittings.A particularly preferred use includes the application for lubricating systems that are in contact with drinking water, in particular gas and (drinking) water fittings.

[0117] The grease is also particularly suitable for lubricating joints and actuators in automobiles. The grease is particularly suitable for lubricating ball joints, especially for commercial vehicles and / or PA-overmolded joints, for sunroofs, spindle drives, especially spindle drives with nuts, for example, for rear-axle steering and / or parking brakes, for actuators, especially with sintered components, for belt starters and / or planetary gears.

[0118] In a preferred embodiment of the invention, the lubricating grease is used to lubricate ceramic friction partners. The lubricating grease is particularly suitable for lubricating tribosystems consisting of ceramic friction partners. It was surprisingly found that the lubricating grease exhibits almost equivalent performance to PTFE in these applications, thus eliminating the need for PTFE.

[0119] The invention is explained in more detail below using several non-limiting examples.

[0120] Two greases according to the invention with the following compositions are prepared.

[0121] Example 1 Inventive grease 1

[0122] The proportion of overbased calcium sulfonate thickener is calculated by adding the following proportions: Calcium sulfonate

[0123] Calcium alkylbenzylsulfonate

[0124] Calcium carbonate with a proportion of crystalline calcium carbonate

[0125] Calcium carbonate crystalline. In this case, a complete

[0126] Conversion to crystalline calcium carbonate instead of calcium carboxylate

[0127] Calcium 12-Hydroxystearate, Ca Acetate.

[0128] Example 2 Inventive grease 2 * Base oil viscosity Si oil mixture 1000 mm 2 / sec at 40°C

[0129] The calculation of the proportion of overbased calcium sulfonate thickener is carried out as in Example 1. Example 3: Addition of silicone oil with conventional liquid additives. An attempt is made to improve the performance of silicone oil with conventional liquid additives.

[0130] It is evident that the performance of silicone oil cannot be improved with the selected liquid additives. Example 4: Miscibility tests of silicone oil and PAO

[0131] The miscibility of silicone oil and PAO in various proportions is tested. The mixture is mixed in a beaker with a magnetic stirrer.

[0132] It turns out that PAO and silicone oil are not homogeneously miscible in the specified proportions.

[0133] Example 5: Preparation of the inventive greases 3 to 32 and the reference greases 33 and 34

[0134] Grease 3:

[0135] Grease 4:

[0136] Grease 5:

[0137] Grease 6:

[0138] Grease 7:

[0139] Grease 8:

[0140] Grease 9:

[0141] Grease 10:

[0142] Grease 11: Calcium carbonate crystalline

[0143] Grease 12:

[0144] Grease 13:

[0145] The proportion of calcium carbonate powder is not included in the proportion of overbased calcium sulfonate thickener because it has a larger particle size and because it is added after the thickener is formed.

[0146] Grease 14:

[0147] The proportion of calcium carbonate powder is not included in the proportion of overbased calcium sulfonate thickener because it has a larger particle size and because it is added after the thickener is formed.

[0148] Grease 15:

[0149] Grease 16: Grease 17:

[0150] The proportion of calcium carbonate powder is not included in the proportion of overbased calcium sulfonate thickener because it has a larger particle size and because it is added after the thickener is formed.

[0151] Grease 18:

[0152] The proportion of calcium carbonate powder is not included in the proportion of overbased calcium sulfonate thickener because it has a larger particle size and because it is added after the thickener is formed.

[0153] Grease 19:

[0154] Grease 20 Calcium carbonate powder

[0155] 5.21% (d50 2.2 pm)

[0156] The proportion of calcium carbonate powder is not included in the proportion of overbased calcium sulfonate thickener because it has a larger particle size and because it is added after the thickener is formed.

[0157] Grease 21 Lithium 12-oxystearate (d50 19 pm)

[0158] The proportion of calcium carbonate powder is not included in the proportion of overbased calcium sulfonate thickener because it has a larger particle size and because it is added after the thickener is formed.

[0159] Grease 22: Grease 23:

[0160] The calcium carbonate powder is not included in the overbased calcium sulfonate thickener ratio because it has a larger particle size and is added after the thickener is formed. Grease 24:

[0161] Grease 25:

[0162] Grease 26:

[0163] The proportion of calcium carbonate powder is not included in the proportion of overbased calcium sulfonate thickener because it has a larger particle size and because it is added after the thickener is formed.

[0164] Grease 27:

[0165] The proportion of calcium carbonate powder is not included in the proportion of overbased calcium sulfonate thickener because it has a larger particle size and because it is added after the thickener is formed.

[0166] Grease 28:

[0167] The proportion of calcium carbonate powder is not included in the proportion of overbased calcium sulfonate thickener because it has a larger particle size and because it is added after the thickener is formed.

[0168] Grease 29:

[0169] The proportion of calcium carbonate powder is not included in the proportion of overbased calcium sulfonate thickener because it has a larger particle size and because it is added after the thickener is formed.

[0170] Grease 30:

[0171] The proportion of calcium carbonate powder is not included in the proportion of overbased calcium sulfonate thickener because it has a larger particle size and because it is added after the thickener is formed.

[0172] Grease 31:

[0173] The proportion of calcium carbonate powder is not included in the proportion of overbased calcium sulfonate thickener because it has a larger particle size and because it is added after the thickener is formed.

[0174] Grease 32: Reference grease 33 (not according to the invention):

[0175]

[0176] Reference grease 34 (not according to the invention):

[0177] The following describes the production of two greases according to the invention as examples. The other greases were obtained by adjusting the raw materials and quantities used.

[0178] I. Preparation of the lubricating grease according to the invention 30

[0179] 26.5 parts by weight of a 400 TBN overbased calcium sulfonate (with amorphous calcium carbonate dispersed therein) are added to an open stirred tank, followed by 40.1 parts by weight of a silicone oil with a viscosity of approximately 1000 mm 2 / s at 40°C.

[0180] Start mixing without heat with a stirrer

[0181] Subsequently, 2.60 parts by weight of a mixture of C10-C13 alkylbenzenesulfonic acid, followed by 0.6 parts by weight of 12-hydroxystearic acid, are added. The mixture is then heated. When the mixture has reached a temperature of 50°C, 1.0 parts by weight of acetic acid are added. After stirring for 15 minutes, 0.7 parts by weight of propylene glycol and 3.1 parts by weight of water are added as a swelling agent. The mixture is heated to 90°C. The temperature is maintained at 85-95°C for 1 hour until Fourier transform spectroscopy shows that the conversion of amorphous calcium carbonate to crystalline calcium carbonate (calcite) has taken place.

[0182] The resulting grease is further heated to approximately 150°C and held at this temperature for 30 minutes, then 5 parts by weight of lithium soap are added. After 30 minutes, the remainder of the silicone oil, with a viscosity of approximately 1000 mm, is added. 2 / s at 40°C, added for cooling. When the fat has cooled to 120°C, 5.0 parts by weight of calcium carbonate powder are added.

[0183] Stirring continues until the fat reaches a temperature of 60°C. Then, 4.0 parts by weight of (highly dispersed) silica and 2.0 parts by weight of hydrotalcite are added as co-thickeners and stirred for one hour. After this step, the fat is removed from the kettle and homogenized on a three-roll mill to achieve the final homogeneous texture.

[0184] II. Production of the lubricating grease according to the invention 32

[0185] 40 parts by weight of a 400 TBN overbased calcium sulfonate (with amorphous calcium carbonate dispersed therein) are added to an open stirred vessel, followed by 30 parts by weight of a silicone oil with a viscosity of approximately 1000 mm 2 / s at 40°C.

[0186] Start mixing without heat with a stirrer

[0187] Next, 3.8 parts by weight of a mixture of C10-C13 alkylbenzenesulfonic acid, followed by 0.8 parts by weight of 12-hydroxystearic acid, are added. The mixture is then heated. When the mixture has reached a temperature of 50°C, 1.5 parts by weight of acetic acid are added. After stirring for 15 minutes, 1.1 parts by weight of propylene glycol and 4.6 parts by weight of water are added as a swelling agent. The mixture is heated to 90°C. The temperature is maintained at 85-95°C for 1 hour until Fourier transform spectroscopy shows that the conversion of amorphous calcium carbonate to crystalline calcium carbonate (calcite) has taken place. The resulting fat is further heated to approximately 150°C and held at this temperature for 30 minutes. After 30 minutes, the rest of the silicone oil, with a viscosity of approx. 1000 mm 2 / s at 40°C, added for cooling until the fat reaches a temperature of 60°C. After this step, the fat is removed from the kettle and homogenized on the three-roll mill to achieve the final homogeneous texture.

[0188] Example 6: Conducting the faucet screening test:

[0189] This test bench tests the feel and operating feel of faucets depending on the lubricating grease used in the cartridge. PTFE dimethylsilicone oil paste (V25 = 1350 mm) is used as the reference grease. 2 / s) is used.

[0190] Test setup:

[0191] Three identical faucets are installed in a row and connected to a water supply.

[0192] For testing, the cartridges are each greased with the same amount of grease (1 g). The greased cartridges are then inserted into the faucets and tightened with a torque wrench of 8 Nm.

[0193] To ensure comparable testing, the reference grease is always used for the center faucet. The tested greases are used for the left and right faucets.

[0194] The haptic tests of the faucets are conducted with water at a pressure of 3 bar. One cycle consists of 8 sections and lasts approximately 15 seconds.

[0195] The structure of the haptic tests is as follows: 1. Starting position (closed)

[0196] 2. Open in mixed water

[0197] 3. Closing from mixed water

[0198] 4. Turn 45° towards hot water

[0199] 5. Open in hot water

[0200] 6. Turn 90° from hot to cold water

[0201] 7. Closing cold water

[0202] 8. Turn 45° to start position

[0203] The testing of the lubricating greases is always carried out by the same inspector and the results are statistically verified by the involvement of at least one other inspector.

[0204] Test procedure: Open

[0205] 1. Opening and closing the faucet greased with the reference grease

[0206] 2. Opening and closing of the taps greased with the greases to be tested in comparison

[0207] 3. Repeat steps 1 and 2.

[0208] The taps are opened within one second. The tap remains open for approximately three seconds. The tap is then closed, again within one second.

[0209] Test procedure: Turning

[0210] 1. 45° turn of the taps to cold water

[0211] 2. 45° turn back to mixed water

[0212] 3. 45° turn to hot water

[0213] 4. Repeat step 2. The 45° turns are performed within one second each. The faucet remains in the turned position (right, left, or center) for approximately two seconds. These turns are performed as described above under the "Turning Test Procedure" section.

[0214] The test sequence for turning takes place in the open state.

[0215] The haptics and operating feel of the faucets are evaluated according to the following scheme:

[0216] The evaluation distinguishes between turning (temperature control) and opening and closing the tap.

[0217] Depending on the feel and operating feel of the faucet, the lubricating greases are rated as follows:

[0218] 0 = Performance of the grease reaches the performance of the comparison grease

[0219] -0.5 = Grease shows almost the same performance as the reference grease

[0220] -1 = Grease shows slightly worse performance than the comparison grease

[0221] -2 = Grease shows significantly worse performance than the comparison grease

[0222] -3 = Grease shows very poor performance

[0223] Example 7: Evaluation of selected lubricating greases in a faucet screening test. Selected lubricating greases were tested in a faucet screening test and evaluated against each other. The results are presented in the table below.

[0224] The lubricating greases 30 and 31 according to the invention almost achieve the haptics of the PTFE comparison lubricating grease, while the non-inventive reference lubricating greases are significantly worse and unsuitable for the application.

Claims

Patent claims 1. A lubricating grease comprising from 30% to 60% by weight of silicone oil, from 10% to 35% by weight of polyalphaolefin, from 10% to 45% by weight of overbased calcium sulfonate thickener, the amounts being based on the total weight of the lubricating grease.

2. Lubricating grease according to claim 1, characterized in that the lubricating grease contains no polytetrafluoroethylene and / or contains polytetrafluoroethylene in a proportion of less than less than 1 wt.%, more preferably less than 0.5 wt.%, more preferably less than 0.1 wt.%, in each case based on the total weight of the lubricating grease.

3. Lubricating grease according to claim 1 or 2, characterized in that the lubricating grease contains no boric acid and no boric acid compounds selected from boric acid, metal borates and boric acid esters and / or contains boric acid and boric acid compounds selected from metal borates and boric acid esters only in a proportion of less than 1 wt.%, based on the total weight of the lubricating grease.

4. Lubricating grease according to one or more of the preceding claims, characterized in that the lubricating grease contains the silicone oil in a proportion of 33 wt.% to 57 wt.%, more preferably 35 wt.% to 55 wt.%, in particular 40 wt.% to 50 wt.%, based on the total weight of the lubricating grease.

5. Lubricating grease according to one or more of the preceding claims, characterized in that the lubricating grease contains 30 wt.% to 60 wt.% dimethyl silicone oil, based on the total weight of the lubricating grease.

6. Lubricating grease according to one or more of the preceding claims, characterized in that the silicone oil has a kinematic viscosity at 25°C of 550 mm 2 / s up to 15,000 mm 2 / s, more preferably 700 mm 2 / s up to 10,000 mm 2 / s, more preferably 800 mm 2 / s up to 8 000 mm 2 / s, measured according to DIN EN 16896 - 2017-02.

7. Lubricating grease according to one or more of the preceding claims, characterized in that the lubricating grease contains polyalphaolefin (PAO) in a proportion of 12 wt.% to 32 wt.%, in particular of 15 wt.% to 30 wt.%, based on the total weight of the lubricating grease.

8. Lubricating grease according to one or more of the preceding claims, characterized in that the polyalphaolefin has a kinematic viscosity at 40°C of 18 mm 2 / s up to 400 mm 2 / s, more preferably 18 mm 2 / s up to 100 mm 2 / s, especially 30 mm2 / s up to 65 mm 2 / s, measured according to DIN EN 16896 - 2017-02.

9. Lubricating grease according to one or more of the preceding claims, characterized in that the lubricating grease comprises overbased calcium sulfonate thickener in a proportion of 15 wt.% to 41 wt.%, more preferably 15 wt.% to 36 wt.%, in particular 16 wt.% to 33 wt.%, based on the total weight of the lubricating grease.

10. Lubricating grease according to one or more of the preceding claims, characterized in that the overbased Calcium sulfonate thickener contains calcium sulfonate, calcium carbonate with a proportion of crystalline calcium carbonate and calcium carboxylate.

11. Lubricating grease according to one or more of the preceding claims, characterized in that the calcium sulfonate contains a calcium salt of an alkylbenzylsulfonic acid of the following formula wherein R1 is selected from C1-C4 alkyl, preferably C2-C4 alkyl and in particular C3 alkyl and R2 is selected from C4-C19 alkyl, preferably C5-C19 alkyl, more preferably C8-C19 alkyl and in particular C9-C19 alkyl in combination with a calcium salt of an alkylbenzylsulfonic acid of the formula wherein R1 is selected from hydrogen and R2 is selected from C3-C25 alkyl, preferably C5-C19 alkyl, more preferably C7-C19 alkyl and especially C10-C19 alkyl.

12. Lubricating grease according to one or more of the preceding claims, characterized in that the overbased calcium sulfonate thickener contains calcium dodecylsulfonate in combination with calcium octadecylsulfonate.

13. Lubricating grease according to one or more of the preceding claims, characterized in that the lubricating grease contains 1 wt.% to 20 wt.%, preferably from 3 wt.% to 15 wt.%, more preferably from 4 wt.% to 11 wt.%, in each case based on the total weight of the lubricating grease, of bentonite and / or pyrogenic silicon dioxide as co-thickener.

14. Lubricating grease according to one or more of the preceding claims, characterized in that the lubricating grease is formulated in such a way that it is approved for occasional contact with foodstuffs, in particular according to EN ISO 21469 (February 2006) Annex B.

15. Use of a lubricating grease according to one or more of the preceding claims for lubricating tribological systems which are in contact with foodstuffs and / or drinking water, in particular of working equipment in food processing and / or for gas and (drinking) water fittings and / or for lubricating joints and actuators in automobiles.

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