EP2154229B1 - Calcium/lithium complex greases, capsuled constant velocity joint containing such lubricant greases, use of same and method for producing same - Google Patents

Description

The invention relates to lubricating greases on calcium / lithium complex soap base, the use of greases for encapsulated constant velocity joints and constant velocity joints provided with such a grease and a method for producing the greases.

For tribosystems, especially those used in many technical applications, it is important to use lubricants to reduce friction and wear on the contact surfaces of moving parts. Depending on the application, lubricants of different consistency can be used. Lubricating oils have a fluid and flowable consistency, while greases have a semi-solid to solid - often gelatinous - consistency.

A characteristic of a lubricating grease is that a liquid oil component is absorbed and retained by a thickener component. The paste-like nature of a lubricating grease and its ability to be spreadable and plastically easily deformed, together with the property to be liable for the fact that the grease wets the lubrication point and unfolds the lubricating effect on the tribologically stressed surfaces.

Greases generally consist of a thickening agent which is homogeneously distributed in a base oil. Frequently, additional auxiliaries, such as emulsifiers, are used so that the thickener is stably dispersed in the base oil. Various substances are known as base oils. The thickeners used are organic and inorganic compounds.

The most important rheological properties of a lubricating grease include the consistency or its yield point, the avoidance of post-hardening and excessive oil separation under thermal and mechanical stress and a stable viscosity-temperature behavior. Often, even with lubricating grease outlet sealed lubrication points, a thixotropic (shear thinning) and shear unstable behavior of the grease advantageous as long as a consistent grease is required only for the assembly of appropriate components. In order to create a grease of high utility value depending on the lubrication and equipment requirements, a high degree of practical experience is required.

Greases are often used in sealed or sealed environments to protect the lubrication point from water, to minimize grease losses, and to prevent the ingress of particles such as sand or dust. A typical application is greased and plastic bellows sealed joints of constant velocity universal joint shafts. The capsule material often makes the movements of the mutually moving parts or at least absorbs vibrations. This requires mobility and, in most cases, elasticity of the material, which must not be adversely affected by contact or interaction with the grease. However, it has been observed that conventional greases attack these capsule materials, causing them, e.g. become brittle and / or damaged by hydrolytic degradation.

Product solutions and industrial property rights for grease lubrication of constant velocity universal joint shafts are mainly concerned with tribological problems and not so much with the question of the supply of tribo-contacts by thixotropic and / or shear unstable fats as well as the compatibility of lubricating grease and bellows material. The continuing miniaturization of constant velocity universal joints in vehicles has, among other things, led to a demand for an improved lubricant to meet the higher requirements of friction and tribology. The inventive novel lubricants have therefore also been developed because they work very well at higher ambient temperatures, which are associated with the continuous development of the vehicle.

For the application of lubricating greases in constant velocity universal joint shafts, these must not have too high yield points, which prevent the grease from automatically flowing back into the lubricating gap after it has been previously, e.g. by centrifugal forces, was ejected from the lubrication gap.

There are numerous formulation patents which relate to the combination of lithium, calcium, lithium complex and polyurea thickeners as a constituent component. examples for this are US-A-4986923 . WO 94/11470 . CN-A-1276412 . US-A-2929782 and WO-A-96/02615 ,

A disadvantage of the prior art is considered that most lithium or lithium complex fats, as well as most lithium / calcium fats have too high shear stability, with the result of increased flexing and thereby caused increased steady-state temperatures in the joint.

This causes a shortened life of the entire system because of the higher thermal stress of the grease and bellows materials. Insufficient subsequent flow of the grease causes a poor supply and thus a poorer wetting of the tribologically stressed surfaces. As a result, this leads to increased wear, combined with a shortening of the service life and to a reduced efficiency due to increased friction.

It has been found that common soap thickeners, in particular the lithium and lithium complex fats widely used in propeller shafts, and polyurea fats have too low an alkaline buffering effect in order to prevent the formation of free acids from the fatty matrix, especially from the fat matrix, during aging of the fat / thermoplastic elastomer (TPE) To prevent additives, and thus the acidic hydrolysis of ester-containing polymer chains. Furthermore, excess lithium hydroxide present in lithium fats in turn provides for alkaline hydrolysis of the ester groups, which also results in a loss of mechanical stability of the bellows. Common urea fats have no or only a relatively small alkali reserve. Acid aging products formed in these fats can not be adequately neutralized.

Object of the present invention is it u.a. to minimize the disadvantages described above in terms of bellows compatibility and the loss of efficiency and service life in drive shafts. The object is solved by the subject matter of the independent claims. Preferred embodiments are subject of the dependent claims or described below.

It has been found that unlike conventional lithium or calcium fats, the calcium / lithium complex soaps (Ca / Li complex soaps) of the present invention having a high calcium content exhibit unexpectedly good properties when used as a constant velocity joint grease. Such products differ significantly from conventional Li / Ca fats. Preference is given to preparing the Ca / Li soaps or the Ca / Li complex soaps in situ using the corresponding carboxylic acid compounds and not by mixing separately prepared Ca and Li soaps or Ca and Li complex soaps. According to the embodiment of the invention, the calcium hydroxide present in excess in conjunction with the Ca / Li complex fat buffers the acidic aging products without significant alkaline hydrolysis of the ester groups of the thermoplastic elastomer due to the comparatively low alkalinity and dissociation of calcium hydroxide.

It has been found that the Ca / Li complex fats are preferably to be prepared in such a way that the amount of lithium compound and calcium compound required for the reaction is dimensioned to ensure that the more reactive lithium compound (presently preferably LiOH) reacted as completely as possible with the carboxyl groups of the carboxylic acids used and the remaining, with the lithium compound unreacted carboxyl groups quasi in excess with calcium compounds (in the present case preferably Ca (OH) ₂ ) are reacted.

Furthermore, the calcium soaps present in excess should lead to a reduced mechanical stability or lower yield point after the entry of the cardan shafts and thus to an improved supply of the friction points in the constant velocity joints.

To reduce the drop point drop observed by the increased calcium level, e.g. to compensate for below 180 ° C, the product formulation includes an additional complexing agent. The composition according to the invention is therefore referred to as Ca / Li complex fat or Ca / Li complex soap fat and not as Ca / Li fat or Ca / Li soap fat.

The use of excess calcium hydroxide and / or excess calcium soaps counteract the acidic aging products, as they also arise through the use of additives. The aging products contribute to the destruction of the bellows.

1. a) einem Basisöl (umfassend eine Basisölmischung), vorzugsweise von 55 bis 92 Gew.% und insbesondere 70 bis 85 Gew.%.,
2. b) Additiven, vorzugsweise von 0,5 bis 40 Gew.% und insbesondere 2 bis 10 Gew.%.,
3. c) Verdicker, wobei der Verdicker eine Komplexseife ist, die eine Calcium/LithiumSeife und 1 bis 20 Gew.% Komplexierungsmittel umfasst, und die Calcium/Lithium-Seife vorzugsweise von 5 bis 25 Gew.% und insbesondere zu 10 bis 20 Gew.% enthalten ist, und
4. d) überschüssigem Ca(OH)₂, vorzugsweise 0,01 bis 2 Gew.%.

The erfindungemäße composition according to claim 1 is independently preferably constructed as follows:

1. a) a base oil (comprising a base oil mixture), preferably from 55 to 92% by weight and in particular 70 to 85% by weight.,
2. b) additives, preferably from 0.5 to 40% by weight and in particular from 2 to 10% by weight.,
3. c) thickener, wherein the thickener is a complex soap comprising a calcium / lithium soap and 1 to 20 wt.% complexing agent, and the calcium / lithium soap preferably from 5 to 25 wt.% and especially 10 to 20 wt.% is included, and
4. d) excess Ca (OH) ₂ , preferably 0.01 to 2 wt.%.

The percentages by weight are based on the total composition and apply in each case independently of one another. A constituent assigned to one of the groups a), b) c) or d) can not simultaneously be part of another group a) to d).

The composition is further characterized by a calcium / lithium molar ratio of greater than 1.0 to 5.0 to 1, preferably 1.2 to 3.0 to 1, and more preferably 1.4 to 2.4 to 1, wherein the ratio is determined by all the calcium and lithium compounds present, ie it is, for example, the existing Ca (OH) ₂ includes.

In particular, the thickener is used in such a way that the composition contains so much thickening agent that a cone penetration value (walk penetration) of 265 to 385 mm / 10 (at 25 ° C.), preferably 285 to 355 mm / 10, is obtained (determined according to DIN ISO 2137 or ASTM D 0217-97).

Suitable base oils are customary lubricating oils which are liquid at room temperature. The base oil preferably has a kinematic viscosity of 20 to 2500 mm ² / s, in particular 40 to 500 mm ² / s at 40 ° C.

The base oils can be classified as mineral oils or synthetic oils. As mineral oils, e.g. Regarding naphthenic mineral oils and paraffinic mineral oils, according to API Group I classification. Chemically modified low aromatics and low sulfur mineral oils with low content of saturated compounds and improved viscosity / temperature behavior compared to Group I oils, classified to API Group II and III also suitable.

Synthetic oils which may be mentioned are polyethers, esters, polyalphaolefins, polyglycols and alkylaromatics and mixtures thereof. The polyether compound may have free hydroxyl groups, but may also be fully etherified or end groups esterified and / or prepared from a starting compound having one or more hydroxy and / or carboxyl groups (-COOH). Also possible are polyphenyl ethers, optionally alkylated, as sole components or even better as mixed components. Suitable for use are esters of an aromatic di-, tri- or tetracarboxylic acid, with one or in mixture C2 to C22 alcohols, esters of adipic acid, sebacic acid, trimethylolpropane, neopentyl glycol, pentaerythritol or dipentaerythritol with aliphatic branched or unbranched, saturated or unsaturated C2 to C22-carboxylic acids, C18 dimer acid esters with C2 to C22 alcohols, complex esters, as individual components or in any desired mixture.

The Ca / Li soap is a mixture of calcium salts and lithium salts of one or more saturated or unsaturated mono-carboxylic acids having 10 to 32 carbon atoms, optionally substituted, in particular having 12 to 22 carbon atoms, more preferably corresponding hydroxycarboxylic acids. Suitable carboxylic acids are, for example, lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid or behenic acid, and preferably 12-hydroxystearic acid. Instead of the free acid group and corresponding lower alcohol esters can be used with saponification, z. B. corresponding triglycerides and the methyl, ethyl, propyl, isopropyl or sec-butyl ester of acid / hydroxy acid to achieve a better dispersion.

1. (a) als fakultativer Bestandteil ein Alkali- (bevorzugt Lithiumsalz), Erdalkali- (bevorzugt Calciumsalz) oder Aluminiumsalz einer gesättigten oder ungesättigten Mono - Carbonsäure oder auch Hydroxycarbonsäuren mit 2 bis 8, insbesondere 2 bis 4 Kohlenstoffatomen oder
   als notwendiger Bestandteil ein Alkali- (bevorzugt Lithiumsalz), Erdalkali- (bevorzugt Calciumsalz) oder Aluminiumsalz einer Di-Carbonsäure mit 2 bis 16, insbesondere 2 bis 12 Kohlenstoffatomen, jeweils ggf. substituiert, und/oder
2. (b) als fakultativer Bestandteil ein Alkali- und/oder Erdalkalisalz der Borsäure und/oder Phosphorsäure, insbesondere Umsetzungsprodukte mit LiOH und/oder Ca(OH)₂.

The Ca / Li soap becomes Ca / Li complex soap by the presence of a complexing agent. Complexing agents in the context of the present invention are:

1. (A) as an optional constituent an alkali metal (preferably lithium salt), alkaline earth metal (preferably calcium salt) or aluminum salt of a saturated or unsaturated mono-carboxylic acid or hydroxycarboxylic acids having 2 to 8, in particular 2 to 4 carbon atoms or
   as a necessary constituent an alkali metal (preferably lithium salt), alkaline earth metal (preferably calcium salt) or aluminum salt of a di-carboxylic acid having 2 to 16, in particular 2 to 12 carbon atoms, in each case optionally substituted, and / or
2. (b) as an optional constituent an alkali metal salt and / or alkaline earth metal salt of boric acid and / or phosphoric acid, in particular reaction products with LiOH and / or Ca (OH) ₂ .

Particularly suitable mono-carboxylic acids are acetic acid and propionic acid. Also suitable are hydroxybenzoic acids such as parahydroxybenzoic acid, salicylic acid, 2-hydroxy-4-hexylbenzoic acid, metahydroxybenzoic acid, 2,5-dihydroxybenzoic acid (gentisic acid), 2,6-dihydroxybenzoic acid (gammaresorcylic acid) or 4-hydroxy-4-methoxybenzoic acid. Adipic acid (C ₆ H ₁₀ O ₄ ), sebacic acid (C ₁₀ H ₁₈ O ₄ ), azelaic acid (C ₉ H ₁₆ O ₄ ) and / or 3- tert -butyl adipic acid (C ₁₀ H ₁₈ O ₄ ).
As borate (b), for example, metaborate, diborate, tetraborate or orthoborate, such as monolithium orthoborate or calcium orthoborate, can be used. Suitable phosphates are alkali metal (preferably lithium) and alkaline earth metal (preferably calcium) dihydrogen phosphate, hydrogen phosphate or pyrophosphate.

In addition, bentonites, such as montmorillonite (whose sodium ions may be exchanged or partially exchanged by ammonium ions), aluminosilicates, clays, silicic acid (eg Aerosil), copper phthalocyanines or else di- and polyureas may additionally be used as co-thickeners.

The compositions according to the invention also contain additives as additives. Usual additives in the context of the invention are antioxidants, anti-wear agents, corrosion inhibitors, detergents, dyes, lubricity improvers, viscosity additives, friction reducers and high-pressure additives.

• Antioxidationsmittel wie Amin-Verbindungen (z.B. Alkylamine oder 1-Phenylaminonaphthalin), aromatische Amine, wie z.B. Phenylnaphtylamine oder Diphenylamine, Phenol-Verbindungen (z.B. 2.6-Di-tert-butyl-4-methylphenol), Sulfurantioxidantien, Zinkdithiocarbamat oder Zinkdithiophosphat;
• Hochdruckadditive wie organische Chlorverbindungen, Schwefel, Phosphor oder Calciumborat, Zinkdithiophosphat, organische Bismuthverbindungen;
• die "Öligkeit" verbessernde Wirkstoffe wie C2- bis C6- Polyole, Fettsäuren, Fettsäureester oder tierische oder pflanzliche Öle;
• Antikorrosionsmittel wie z.B. Petroleumsulfonat, Dinonylnaphtalinsulfonat oder Sorbitanester;
• Metalldeaktivatoren wie z.B. Benzotriazol oder Natriumnitrit;
• Viskositätsverbesserer wie z.B. Polymethacrylat, Polyisobutylen, oligo-Dec-1-ene, und Polystyrole.
• Verschleißschutzadditive und Reibungsminderer wie Organomolybdänkomplexe (OMC), Molybdän-di-alkyl-dithiophosphate, Molybdän-di-alkyl-dithiocarbamate oder Molybdänsulfid-di-alkyl-dithiocarbamate, insbesondere Molybdän-di-n-butyldithiocarbamat und Molybdändisulfid-di-alkyldithiocarbamat (Mo₂O_mS_n(dialkylcarbamat)₂ mit m = 0 bis 3 und n = 4 bis 1) oder aromatische Amine,
• Reibungsminderer wie z.B. funktionelle Polymere wie z.B. Oleylamide, organische Verbindungen auf Polyether- und Amidbasis, z.B. Alkylpolyethylenglykoltetradecylenglykolether oder Molybdändithiocarbamat.

Examples include:

• Antioxidants such as amine compounds (eg, alkylamines or 1-phenylaminonaphthalene), aromatic amines such as phenylnaphthylamines or diphenylamines, phenolic compounds (eg, 2,6-di-tert-butyl-4-methylphenol), sulfuric antioxidants, zinc dithiocarbamate, or zinc dithiophosphate;
• High pressure additives such as organic chlorine compounds, sulfur, phosphorus or calcium borate, zinc dithiophosphate, organic bismuth compounds;
• the "oiliness" improving agents such as C2 to C6 polyols, fatty acids, fatty acid esters or animal or vegetable oils;
• Anti-corrosion agents such as petroleum sulfonate, dinonylnaphthalenesulfonate or sorbitan esters;
• Metal deactivators such as benzotriazole or sodium nitrite;
• Viscosity improvers such as polymethacrylate, polyisobutylene, oligo-dec-1-ene, and polystyrenes.
• Wear protection additives and friction modifiers such as organomolybdenum complexes (OMC), molybdenum di-alkyl dithiophosphates, molybdenum di-alkyl dithiocarbamates or molybdenum sulfide di-alkyl dithiocarbamates, in particular molybdenum di-n-butyl dithiocarbamate and molybdenum disulfide di-alkyl dithiocarbamate (Mo ₂ O _m S _n (dialkylcarbamate) ₂ with m = 0 to 3 and n = 4 to 1) or aromatic amines,
• Friction reducers such as functional polymers such as oleylamides, organic compounds based on polyether and amide, for example Alkylpolyethylenglykoltetradecylenglykolether or molybdenum dithiocarbamate.

In addition, the grease compositions of this invention contain conventional anti-corrosive, oxidative, and anti-metallope additives which act as chelates, radical scavengers, UV transducers, reaction layer formers, and the like.

As solid lubricants , for example, polymer powders such as polyamides, polyimides or PTFE, graphite, metal oxides, boron nitride, metal sulfides such as molybdenum disulfide, tungsten disulfide or mixed sulfides based on tungsten, molybdenum, bismuth, tin and zinc, inorganic salts of alkali and alkaline earth metals, such as calcium carbonate, sodium and calcium phosphates. Solid lubricants can be divided into the following four groups: layered structure compounds such as molybdenum disulfide and tungsten disulfide, graphite, hexagonal boron nitride, and some metal halides; oxidic and hydroxidic compounds of the transition and alkaline earth metals or their carbonates or phosphates; soft metals and / or plastics.

The sealing material , including capsule materials which are in contact with the lubricant, according to a further embodiment of the invention is a polyester, preferably a thermoplastic copolyester elastomer comprising hard segments having crystalline properties and a melting point above 100 ° C and soft segments having a glass transition temperature of less than 20 ° C, preferably less than 0 ° C, have.

Especially suitable are polychloroprene rubber and thermoplastic polyesters (TPE), thermoplastic polyetheresters (TEEE = topographical ether-ester-elastomer). The latter are commercially available under the trade names Arnitel® from DSM, Hytrel® from DuPont and PIBI-Flex® from P-Group.

The WO 85/05421 A1 describes such a suitable polyetherester material for bellows, based on polyether esters. Also, a bellows body as an injection molded part of a thermoplastic polyester elastomer is in the DE 35 08 718 A called.

The hard segments are e.g. derived from at least one aliphatic diol or polyol and at least one aromatic di- or polycarboxylic acid, the soft segments having elastic properties e.g. from ether polymers such as e.g. Polyalkylenoxidglykolen or non-aromatic dicarboxylic acids and aliphatic diols. Such compounds are e.g. referred to as Copolyetherester.

Copolyetherester compositions are used in components, for example, when the component made therefrom is subjected to frequent deformation or vibration. Very well known applications in this context are bellows or bellows for the protection of drive shafts and transmission shafts, joint columns and suspension units as well as sealing rings. In such applications, the material also frequently or continuously comes into contact with lubricants such as greases.

Technically, it is possible to proceed in such a way that the bellows is produced by injection blow molding, injection extrusion or extrusion blow molding, with annular rubber parts possibly being placed in the mold at the two future clamping points.

The resistance of the copolyetherester composition to the effects of oils and fats is one of the reasons for their wide use in addition to their ease of processing into relatively complex geometries.

A grease according to the present invention is preferably, but not exclusively, used for the lubrication of constant velocity joints (constant velocity joint CVJ), as used for example in drive shafts for motor vehicles and machines. The task of a constant velocity joint is the uniform transmission of torque from a shaft to an angularly mounted second shaft at diffraction angles of up to 50 °.

In motor vehicle constant velocity joints are used in particular in front-wheel drive and all-wheel drive vehicles and generally divided into two groups: constant velocity fixed joints and constant velocity sliding joints. The group of constant velocity joints includes Ball Joints (BJ) and constant velocity joints ("Undercut Free" UJ). The group of constant velocity joints are Tripod Joints (TJ), Double Offset Joints (DOJ) and Cross Groove Joints (Cross Groove Joins LJ). In contrast to the constant velocity fixed joints, synchronized sliding joints not only ensure uniform torque transmission at different bend angles, but also provide length compensation for the drive shaft connecting the gearbox to the wheel.

Since constant velocity joints are lubricated almost exclusively with lubricating greases, they are usually encapsulated with a bellows to prevent grease leakage or the ingress of dirt or moisture. This bellows is usually made in one piece and is slipped over the drive shaft after lubrication or assembly of the constant velocity joint.

• Fig.1 die Walkbeständigkeit der Beispielfette nach DIN ISO 2137,
• Fig. 2 bis 5 die Verträglichkeit der Fette gemäß Versuchsbeispielen mit verschiedenen TEEE-Balgmaterialien, dargestellt über die prozentuale Änderung der Reißdehnung nach thermischer Alterung im Schmierfett,
• Fig. 6 die mittlere Lebensdauer von Gleichlauffestgelenken, dargestellt in der Anzahl der Überrollungen und
• Fig. 7 den Wirkungsgrad von Gleichlauffestgelenken, dargestellt mit der mittle-ren Beharrungstemperatur über die gesamte Prüfdauer.

The property profile of the different fats, as prepared below, is further characterized by the figures and Table 1. Show it:

• Fig.1 the flexing resistance of the example greases according to DIN ISO 2137,
• Fig. 2 to 5 the compatibility of the fats according to experimental examples with different TEEE bellows materials, represented by the percentage change in elongation at break after thermal aging in the lubricating grease,
• Fig. 6 the mean life of constant velocity joints, shown in the number of rolls and
• Fig. 7 the efficiency of constant velocity joints, represented by the mean steady state temperature over the entire test period.

• Fig.1: Änderung der Konsistenz nach Pw 100.000 Doppeltakten nach DIN ISO 2137 in Abhängigkeit des Ca/Li-Verhältnisses
• Fig. 2: Änderung der Reißdehnung bei TPE ARNITEL EB 464 nach DIN 53455 nach 336 stündiger Einlagerung im Schmierfett bei 125 °C
• Fig. 3: Änderung der Reißdehnung bei TPE HYTREL 8105 BK nach DIN 53455 nach 336 stündiger Einlagerung im Schmierfett bei 125 °C
• Fig. 4: Änderung der Reißdehnung bei TPE HYTREL 8223 BK nach DIN 53455 nach 336 stündiger Einlagerung im Schmierfett bei 125°C
• Fig. 5: Änderung der Reißdehnung bei TPE PIBE-FLEC 5050 nach DIN 53455 nach 336 stündiger Einlagerung im Schmierfett bei 125°C
• Fig. 6: Lebensdauer auf dem Gelenkwellenprüfstand "GIM Four Square Test Rig" im UF Festgelenk Verspannmoment 500 Nm, Beugewinkel 10°, Drehzahl 250 rpm
• Fig.: 7: Beharrungstemperatur auf dem Gelenkwellenprüfstand "GIM Four Square Test Rig" im UF Festgelenk Verspannmoment 500 Nm, Beugewinkel 10°, Drehzahl 250 rpm

In detail, the figures show:

• Fig.1 : Change in consistency to Pw 100,000 double cycles according to DIN ISO 2137 depending on the Ca / Li ratio
• Fig. 2 : Change in elongation at break with TPE ARNITEL EB 464 according to DIN 53455 after 336 hours of storage in the lubricating grease at 125 ° C
• Fig. 3 : Change in elongation at break for TPE HYTREL 8105 BK according to DIN 53455 after 336 hours of storage in the lubricating grease at 125 ° C
• Fig. 4 : Change in elongation at break for TPE HYTREL 8223 BK according to DIN 53455 after 336 hours of storage in the lubricating grease at 125 ° C
• Fig. 5 : Change in elongation at break for TPE PIBE-FLEC 5050 according to DIN 53455 after 336 hours of storage in the lubricating grease at 125 ° C
• Fig. 6 : Service life on the cardan shaft test rig "GIM Four Square Test Rig" in the UF fixed joint Tensioning torque 500 Nm, bending angle 10 °, speed 250 rpm
• Fig .: 7 : Steady-state temperature on the cardan shaft test rig "GIM Four Square Test Rig" in the UF fixed joint clamping torque 500 Nm, bending angle 10 °, speed 250 rpm

The production of greases can be done as follows, for example:
Mixing the salt / metal compound into the carboxylic acid compound which may optionally be extended with the base oil component, and optionally simultaneously heating the mixture to a temperature above 70 ° C to form a thickened grease product, cooling the grease product and optionally adding water, Shearing forces on the mixture, eg with a tooth colloid mill, a high pressure homogenizer and / or a three roll mill.

For this purpose, a vessel is charged with a stirrer in a first step at a speed of 0 to 150 U / min with 3 to 40% by weight of the educt components of the thickener and 20 to 90% by weight of the base oil, based on the total weight of the finished grease composition.

According to a preferred embodiment of the invention, the thickener is synthesized in situ in the base oil, preferably under pressure and at elevated temperature in a closed reaction vessel, such as an autoclave.

Preparation Example A to C (Comparative Example)
The preparations of the example formulations AC are based on known and customary processes for preparing corresponding thickeners.

Production description Example E:
In a reactor, 1240 g of 12-hydroxystearic acid (12-HSA) and 560 g of sebacic acid were placed in 12,000 g of a base oil mixture and heated with stirring until the 12-HSA was melted. In the next step, 125 g LiOH and 295 g Ca (OH) _{2 were} added. The Ca (OH) ₂ was dissolved in 300g of water prior to addition to the reactor. The batch was heated in a predetermined temperature program to the intended maximum process temperature with stirring. In the cooling phase, additives were added to the batch at certain temperatures. After adjusting the batch to the desired consistency by adding 5,400 g of the base oil mixture, the final product was homogenized by tooth colloid mill.

Preparation Example D and G: The preparation of the example formulations was carried out analogously to the example formulation E with modification of the LiOH and Ca (OH) ₂ amounts. <b> Table 1: Formulation Examples </ b> Example A Example B Example C Example D Example E Example G Reference A Reference B Reference C invention invention invention thickener LiX + Ca LiX + CaX LiX / CaX CaX / LiX CaX / LiX CaX / LiX manufacturing 1/1 compound 1/1 compound in situ in situ in situ in situ Amount of Ca [mol%] 0010 0019 0011 0016 0020 0024 Molar amount of Li [mol%] 0033 0033 0028 0016 0015 0012 Factor Substance% Ca / Li 12:31 12:58 12:39 1:01 1:35 2:04 1. formulation 1.1 fatty acids: 12-HSA 7:34 4:39 6.64 7.95 7.69 7:52 mixed fatty acid 2.78 beef tallow 2.68 1.2 Alkali: LiOH * H2O 1:39 1:39 1.18 0.67 0.62 12:50 Ca (OH) 2 0.77 1:42 0.82 1.20 1:48 1.80 1.3 Complexing agent: azelaic acid 1:59 1:59 sebacic 2:32 2.78 2.83 2.85 acetic acid 2:42 trisodium phosphate 12:13 disodium 12:13 1.4 base oils: naphthenic base oil 49.60 34.37 43.17 41.20 41.50 40.62 Paraffin-based base oil 34.85 44.20 41.37 41.70 41.38 42.12 1.5 additives: Antioxidant 1 12:50 12:50 12:50 12:50 12:50 12:51 Antioxidant 2 12:50 12:50 12:50 12:50 12:50 12:51 EP / AW 12:50 12:50 12:50 12:50 12:50 12:51 Solid lubricant 1 0.99 1:00 1:00 1:00 1:00 1:02 Solid lubricant 2 1.98 2:00 2:00 2:00 2:00 2:04

Claims (15)

1. Calcium/lithium-complex grease composition comprising:

   a) at least one base oil,

   b) at least one additive,

   c) at least one thickener, wherein the thickener is a complex soap, comprising a calcium/lithium soap and at least one complexing agent, wherein the complexing agent is an alkali salt, and alkaline earth salt or an aluminum salt of a dicarboxylic acid having 2 to 16 carbon atoms, optionally substituted, and

   d) an excess of Ca(OH)₂,

   wherein the composition comprises a calcium to lithium molar ratio of greater than 1.0 to 5.0 : 1, with reference to the ratio of all calcium and lithium atoms present in the calcium- and lithium compounds.
2. Composition according to claim 1, characterized in that the composition contains:

   a) 55 to 92 wt.%, in particular 70 to 85 wt.%, of the base oil,

   b) 0,5 to 40 wt.%, in particular 2 to 10 wt.% of the additive,

   c) 5 to 25 wt.% calcium/lithium-soaps and
   1 to 20 wt.% of the complexing agent, and

   d) excess Ca(OH)₂, preferably 0,01 to 2 wt%,

   each amount being relative to the total composition.
3. Composition according to at least one of the preceding claims, characterized in that the composition has a cone penetration value (walk penetration) of 265 to 385 mm/10 (at 25°C), preferably 285 to 355 mm/10, determined according to ISO 2137.
4. Composition according to at least one of the preceding claims, characterized in that the base oil has a kinematic viscosity of 20 to 2500 mm²/s, preferably of 40 to 500 mm²/s, at 40 °C.
5. Composition according to at least one of the preceding claims, characterized in that the calcium/lithium soap is a mixture or conversion product respectively of a lithium salt and calcium salt of a saturated or unsaturated monocarboxylic acid having 10 to 32 carbon atoms, optionally substituted, particularly preferred of corresponding hydroxycarboxylic acids.
6. Composition according to at least one of the preceding claims, characterized in that the complexing agent consists of :

   - an alkali salt, preferably lithium salt, an alkaline earth salt, preferably calcium salt, or an aluminum salt of a dicarboxylic acid having 2 to 16 carbon atoms, optionally substituted.
7. Composition according to claim 1, characterized in that the at least one complexing agent is a lithium salt or calcium salt of a dicarboxylic acid having 2 to 12 carbon atoms, optionally substituted.
8. Composition according to at least one of the preceding claims, characterized in that the calcium to lithium molar ratio calculated based on the molar ratio of LiOH*H₂O to Ca(OH)₂ is from 1,2 to 5,0 : 1, from 1,2 to 3,0 : 1 and in particular from 1,4 to 2,4 : 1.
9. Composition according to at least one of the preceding claims, characterized in that the thickener is obtainable by joint conversion of at least one calcium-compound and at least one lithium compound with carboxylic acids and/or the substituted carboxylic acids in the presence of the complexing agent, and the calcium-compound(s) are used in molar excess and at least one calcium-compound is Ca(OH)₂.
10. The constant velocity joint having an encapsulation in the area of a lubrication point, wherein the encapsulation comprises a thermoplastic elastomer containing ester compounds or consists thereof and the encapsulation includes a composition according to at least one of the preceding claims.
11. The constant velocity joint according to claim 10, characterized in that the encapsulation

    a) consists of or includes polyetheresters and/or

    b) the encapsulation is a boot.
12. Use of the composition according to at least one of claims 1 to 9 for lubrication of at least one constant velocity joint, preferably as part of homokinetic joint shafts.
13. Use according to claim 12, characterized in that the constant velocity joint comprises an encapsulation, preferably of a thermoplastic elastomer, in the area of lubrication point and the encapsulation preferably is a boot.
14. Process for the production of a calcium/lithium-complex grease composition comprising or consisting of:

    a) at least one base oil,

    b) at least one additive,

    c) at least one thickener, wherein the thickener is a complex soap comprising a calcium/lithium soap and at least one complexing agent, and

    an excess of Ca(OH)₂,
    and wherein the complexing agent is an alkali salt, and alkaline earth salt or an aluminum salt of a dicarboxylic acid having 2 to 16 carbon atoms, optionally substituted,
    wherein the composition comprising a calcium to lithium molar ratio of greater than 1.0 to 5.0 to 1, with respect to the ratio of all calcium and lithium atoms present in the calcium- and lithium compositions,
    wherein at least one calcium-compound and at least one lithium compound together being converted "in-situ" with carboxylic acids, optionally substituted in whole or in part, and the thickener, and the calcium-compound(s) are used in molar excess and at least one calcium-compound is Ca(OH)₂.
15. Process according to claim 14, characterized in that the carboxylic acids being substituted carboxylic acids, preferably hydroxy carboxylic acids.

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