DE102011108575A1 - Preparing lignin sulfonate containing greases comprises mixing a base oil, calcium soap, complexing agent and calcium lignin sulfonate and heating to obtain base grease, and cooling base grease and adding base oil and optionally additives - Google Patents

Abstract

Preparing lignin sulfonate containing greases comprises (a) mixing at least a base oil, a calcium soap, optionally prepared in situ, with >= 10 carbon atoms, where at least calcium hydroxide is added when the calcium soaps is prepared in situ, a complexing agent, a calcium lignin sulfonate having an average molecular weight of = 10000 g/mole, and heating to >= 120[deg] C to obtain a base grease under the removal of low boiling components; and (b) cooling the base grease and adding base oil and optionally additives, with mixing. Independent claims are included for: (1) a grease composition comprising 55-92 (preferably 70-85) wt.% of the base oil, 0-40 (preferably 2-10) wt.% of additives, 3-40 (preferably 5-20) wt.% of calcium soaps, 0.5-20 (preferably 0.5-10) wt.% of complexing agent, 0.01-2 wt.% of optionally excess calcium hydroxide, 0.5-50 (preferably 2-8) wt.% of calcium lignin sulfonate and optionally further alkaline earth lignin sulfonates; and (2) a constant velocity joint shaft comprising the grease composition to at least one lubricating point, where the constant velocity joint comprises an encapsulation in the region of the lubrication point, where the encapsulation is bellows.

Description

The invention relates to a process for the production of calcium lignosulfonate-containing greases, such lubricating greases and their use, in particular in constant velocity universal joint shafts.

Lignin is a complex polymer based on phenylpropane units, which are interlinked with each other with a range of different chemical bonds. Lignin occurs in plant cells together with cellulose and hemicellulose. Lignin itself is a cross-linked macromolecule.

As monomer components of lignin, it is possible to identify essentially 3 types of monolignol monomers, which differ in their degree of methoxylation. These are p-cumaryl alcohol, coniferyl alcohol, and sinapyl alcohol. These lignols are incorporated into the lignin structure in the form of hydroxyphenyl (H), guaiacyl (G), and syn-ring (S) units. Naked plants (gymnosperms) such. B. Pines contain overwhelmingly G units and low levels of H units. All lignins contain small amounts of incomplete or modified monolignols. The primary function of lignins in plants is to confer mechanical stability by cross-linking the plant polysaccharides. Lignin represents about 1/3 of the dry mass of wood and roughly represents 30% of the non-fossil organic carbon mass on Earth. It is the third most common organic material after cellulose and chitin and thus also a very readily available renewable raw material for industrial products.

Lignosulfonate is a by-product of papermaking with the sulfite process. In this process, comminuted wood chips are heated under pressure (for example 5 to 7 bar) for about 7 to 15 hours in the presence of calcium bisulfite liquor and then the lignosulfonic acid in the form of calcium lignosulfonate is removed from the lignocellulose by a washing and precipitation process. Instead of calcium hydrogen sulfite, it is also possible to use magnesium, sodium or ammonium sulfite bases, which leads to the corresponding magnesium, sodium and ammonium salts of lignosulfonic acid. Evaporation of the wash liquor gives powdered lignosulfonates. The annual worldwide production of lignosulfonates amounts to approx. 55 million tons.

Sodium, calcium and magnesium lignosulfonates are widely used as a base for the plasticization and liquefaction of concrete and mortar. Another use find lignosulfonates as Pelletierhilfsmittel in the concentrated feed industry and in other areas as a dispersant or complexing agent.

Tribochemically acting extreme pressure (high pressure) and anti-wear (EP / AW) additives used in today's grease formulations account for a not inconsiderable amount of formulation costs and are thus often the price-driving factor for greases.

Many of these additives are prepared in elaborate multi-step synthesis procedures, and their use is limited by the toxicological side effect that occurs in many cases, both in their mode of use and in their use concentration in the final formulation. In some applications, e.g. As in constant velocity universal joint or in slow-moving and highly loaded bearings can not be avoided by liquid additives lack of lubrication conditions or a touch of the friction partners. In these cases, solid lubricants based on inorganic compounds (eg Ca and Zn phosphate salts), plastic powders (eg PTFE) or metal sulfides (eg MoS ₂ ) have been used in the past practice. These components are often expensive and have a significant impact on the overall cost of a lubricant formulation.

Previous practice in the production of grease is the addition of these additives in a second, downstream of the actual chemical reaction process of thickening process step. In this additive, especially solid lubricants must be distributed by intensive mixing and shearing processes with increased mechanical effort homogeneously in the relatively high viscosity grease to achieve their optimum effect. From today's perspective, the following often proves to be disadvantageous and has given rise to the present invention. Common lubricant additives and solid lubricants are based i. d. R. not on renewable resources and are often difficult to biodegrade.

In addition, most common wear protection additives and friction-reducing lubricant additives require a complex synthetic chemistry and therefore represent a major cost factor. Therefore, especially when using solid lubricants for highly loaded friction points dominate comparatively expensive materials such as MoS ₂ or PTFE.

Task / Advantage of the invention

The object of the invention is therefore to avoid the disadvantages of the prior art described above, and to provide lignosulfonates both as a cost structurant and as a wear-protective, friction-reducing and anti-aging additive in lubricating greases and at the same time to provide good water resistance of the greases.

Due to the presence of lignosulfonate, the use of other common lubricant additives and solid lubricants, in particular MoS ₂ , can be minimized or even dispensed with.

Summary of the invention

The invention is characterized by the independent claims. Preferred embodiments are subject of the dependent claims or described below.

• – Grundöl
• – Fettsäuren und/oder deren Ester oder deren Salze, wobei das Fettsäuresalz zumindest teilweise ein Calciumsalz ist, zur Herstellung von Seifen enthaltend zumindest Calciumseifen,
• – organische und/oder anorganische Komplexierungsmittel,
• – Erdalkalihydroxide, wobei die Erdalkalihydroxide zumindest CaOH umfassen,
• – ggf. Wasser (z. B. als Teil der Hydroxide) und
• – Ca-Ligninsulfonat, insbesondere mit mittleren Molekulargewichten (Gewichtsmittel) von 10000 g/mol und kleiner,

um durch Erhitzen das Austreiben niedrig siedender Komponenten, bei Einsatz von Estern, und zumindest eine Umsetzung des Erdalkalihydroxids mit den Fettsäuren und/oder deren Estern und dem Ligninsulfonat zu bewirken, einschließlich der Umsetzung mit den Komplexierungsmitteln, soweit mit den Erdalkalihydroxiden umsetzbare Komplexierungsmittel eingesetzt werden, zur Bildung einer Verdickerstruktur im Grundöl.According to the method on which the present invention is based, a precursor (base fat) is first prepared by joining at least one of them

• - base oil
• Fatty acids and / or their esters or their salts, where the fatty acid salt is at least partially a calcium salt, for the preparation of soaps containing at least calcium soaps,
• Organic and / or inorganic complexing agents,
• Alkaline earth hydroxides, the alkaline earth hydroxides comprising at least CaOH,
• Optionally water (eg as part of the hydroxides) and
• Ca lignosulphonate, in particular with weight average molecular weights of 10000 g / mol and smaller,

to effect by heating the expulsion of low-boiling components, using esters, and at least one reaction of the alkaline earth metal hydroxide with the fatty acids and / or their esters and the lignosulfonate, including the reaction with the complexing agents, as far as usable with the alkaline earth metal hydroxides complexing agents, to form a thickener structure in the base oil.

Low boiling components are those components which boil at about 100 ° C at normal pressure, such as water or C 1 to C 4 alcohols.

Preferably, to produce the base fat to temperatures of about 120 ° C or better above 180 ° C heated. The conversion to the base fat takes place in a heated reactor, which can also be designed as an autoclave or vacuum reactor.

Subsequently, in a second step by cooling, the formation of the thickener structure is completed and, if appropriate, further constituents, such as additives and / or base oil, are added to set the desired consistency or the desired property profile. The second step may be carried out in the reactor of the first step, but preferably the base grease from the reactor is transferred to a separate stirred tank for cooling and mixing in the optional further constituents.

If necessary, the resulting grease is homogenized, filtered and / or vented.

Ca / Li, Li / Ca and calcium thickened complex soap fats are preferably used in which calcium lignosulfonate is added before the reaction phase to produce the base fat and incorporated into the grease structure via a thermal process in such a way that it is in a very homogeneous oil-insoluble form is present, which leads to high dropping point temperatures.

The use of alkaline earth salts, preferably calcium salts, both on the side of the fatty acid salts and the lignosulfonate ensures that no salification takes place both in the preparation of the base fat and in the application.

The salification, in particular to the sodium salts, must be prevented according to the invention to obtain a lignosulfonate-containing grease with good water resistance and at the same time high dropping point. Therefore, avoid the use of sodium lignosulfonate and sodium hydroxide. By water resistance is meant that the fat according to the test DIN 51807-1 (Issue: 1979-04) is not emulsified by water or corresponds to the evaluation level 1-90 (test at 90 ° C). Under water resistance it is also understood that fat according to test DIN 51807-2 (Edition 1990-03) the rating level 1-80 (test at 80 ° C) corresponds.

By the simultaneous use of an excess of alkali in the form of excess calcium hydroxide and optionally additionally calcium acetate or other calcium salts as a complexing agent to ensure that even small residues of free sulfonic acid groups are neutralized in the lignosulfonic acid and removed hygroscopic and water-emulsifying and corrosive action. By a high process temperature of greater than 120 ° C, in particular greater than 180 ° C is additionally ensured that the residual moisture still registered in the lignosulfonate is completely evaporated from the reaction medium and possibly neutralized components of the lignosulfonate are neutralized by calcium hydroxide.

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 z. B. considers naphthenic and paraffinic mineral oils according to classification API Group I. Chemically modified low-aromatic and low-sulfur mineral oils with low content of saturated compounds and improved viscosity / temperature behavior compared to Group I oils, classified according to API Group II and III.

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 also be completely etherified or esterified ester groups and / or be prepared from a starting compound with 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 soaps produced are either pure calcium soaps or mixtures containing calcium soaps, in particular besides calcium soaps also lithium soaps and / or aluminum soaps, one or more saturated or unsaturated mono-carboxylic acids with 10 to 32 carbon atoms, optionally substituted, in particular with 12 to 22 carbon atoms, particularly preferred corresponding hydroxycarboxylic acids. Suitable carboxylic acids are, for. 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.

• (a) das Alkalisalz (bevorzugt Lithiumsalz), ausgenommen Natriumsalz, Erdalkalisalz (bevorzugt Calciumsalz) und/oder Aluminiumsalz einer gesättigten oder ungesättigten Mono-Carbonsäure oder auch Hydroxycarbonsäuren mit 2 bis 8, insbesondere 2 bis 4 Kohlenstoffatomen oder einer Di-Carbonsäure mit 2 bis 16, insbesondere 2 bis 12 Kohlenstoffatomen, jeweils ggf. substituiert, und/oder
• (b) das Alkali- und/oder Erdalkalisalz der Borsäure und/oder Phosphorsäure, insbesondere deren Umsetzungsprodukte mit LiOH und/oder Ca(OH)₂.

The soap becomes a complex soap by the presence of a complexing agent. The complex soaps invention (presence of a complexing agent) have increased dropping points, z. B. greater than 200 ° C ( DIN ISO 2176 ). Suitably, the complexing agent is used to 0.5 to 20 wt .-%, in particular 0.5 to 10 wt .-%. Complexing agents in the context of the present invention are:

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

The complexing agent (a) is preferably exclusively a calcium salt, in particular if it is used as calcium acetate for the preparation of the base fat. Particularly suitable mono-carboxylic acids are acetic acid and propionic acid. Also suitable are hydroxybenzoic acids such as parahydroxybenzoic acid, salicylic acids, 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. Particularly suitable dicarboxylic acids are 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. As monolithium orthoborate or calcium orthoborate, are 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 with ammonium ions), aluminosilicates, clays, silicic acid (eg Aerosil), oil-soluble polymers (eg polyolefins, poly (meth ) Acrylates, Polyisiobutylene, polybutenes or PS) or di- and polyureas are used as co-thickener. The bentonites, aluminosilicates, clays, silicic acid and / or oil-soluble polymers may be added to make the base fat or added later as an additive in the second step. The di- and polyureas can be added as an additive.

The compositions according to the invention optionally further 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-Phenyl-aminonaphthalin), 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),
• – Reibungsminderer wie z. B. funktionelle Polymere wie z. B. Oleylamide, organische Verbindungen auf Polyether- und Amidbasis, z. B. Alkylpolyethylenglykoltetradecylenglykolether.

Examples include:

• Antioxidants such as amine compounds (eg., Alkylamine or 1-phenyl-aminonaphthalene), aromatic amines, such as. As phenylnaphthylamines or diphenylamines, phenolic compounds (eg, 2,6-di-tert-butyl-4-methylphenol), sulfur 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;
• - Anticorrosion agents such. Petroleum sulfonate, dinonylnaphthalenesulfonate or sorbitan esters;
• - Metal deactivators such. Benzotriazole or sodium nitrite;
• - Viscosity improvers such. Polymethacrylate, polyisobutylene, oligo-dec-1-ene, and polystyrenes.
• Anti-wear 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),
• - friction reducer such. B. functional polymers such. As oleylamides, organic compounds based on polyether and amide, z. B. Alkylpolyethylenglykoltetradecylenglykolether.

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 z. As polymer powder 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. As calcium carbonate, sodium and calcium phosphates are used.

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 desired advantageous lubrication properties can be adjusted by the use of lignosulfonates, without having to use solid lubricants. In many cases, these can be dispensed with completely or at least can be significantly minimized. As far as solid lubricants are used graphite can be used advantageously.

As lignosulfonate calcium lignosulfonates are preferably used with molecular weight (Mw, weight average) of less than 15,000, in particular less than 12,000 or even less than or equal to 10 000 g / mol, which in particular 2 to 12 wt .-%, in particular 4 to 10 wt. -%, sulfur (calculated as elemental sulfur) and / or 5 to 15 wt .-%, in particular 8 to 15 wt .-% calcium (calculated Ca) included. In addition to calcium lignosulfonates, other alkaline earth lignin sulfonates may additionally be used. The weight average molecular weight is z. B. determined by size exclusion chromatography. A suitable method is the SEC-MALLS method as described in the article of GE Fredheim, SM Braaten and BE Christensen, "Comparison of molecular weight and molecular weight distribution of softwood and hardwood lignosulfonates" published in "Journal of Wood Chemistry and Technology", Vol. 23, No. 2, pages 197-215, 2003 (eg Mobile Phase: phosphate-DMSO-SDS, stationary phase: Jordi-glucose DVB as described under 2.5).

• a) 55 bis 92 Gew.-%, insbesondere 70 bis 85 Gew.-%, des Grundöls,
• b) 0 bis 40 Gew.-%, insbesondere 2 bis 10 Gew.-%, Additive,
• c) 3 bis 40 Gew.-%, insbesondere 5 bis 20 Gew.-%, Seifen und
• d) 0,5 bis 20 Gew.-%, insbesondere 0,5 bis 10 Gew.-%, Komplexierungsmittel, und
• e) überschüssiges Ca(OH)₂, vorzugsweise 0,01 bis 2 Gew.-%,
• f) 0,5 bis 45, insbesondere 2 bis 15 Gew.-%, und besonders bevorzug 3 bis 8 Gew.-% Ligninsulfonat insbesondere Calciumligninsulfonat,

jeweils bezogen auf die gesamte Zusammensetzung, wobei die Komponenten und deren Vorzugsvarianten oben definiert sind.The lubricating grease according to the invention is characterized by the following composition:

• a) 55 to 92% by weight, in particular 70 to 85% by weight, of the base oil,
• b) 0 to 40% by weight, in particular 2 to 10% by weight, of additives,
• c) 3 to 40 wt .-%, in particular 5 to 20 wt .-%, soaps and
• d) 0.5 to 20 wt .-%, in particular 0.5 to 10 wt .-%, complexing agent, and
• e) excess Ca (OH) ₂ , preferably 0.01 to 2 wt .-%,
• f) from 0.5 to 45, in particular from 2 to 15,% by weight, and particularly preferably from 3 to 8% by weight of lignosulfonate, in particular calcium lignosulfonate,

in each case based on the entire composition, wherein the components and their preferred variants are defined above.

It has now been found that lignosulfonates act as structure formers for water-resistant lubricating greases with simultaneous properties as solid lubricant or wear protection additive and aging stabilizer. At the same time, surprisingly synergistic effects of lignin sulfonate with other solid lubricants, e.g. B. observed with graphite or calcium carbonate.

It has also been found that lignosulfonates are multifunctional components for lubricants. Due to their high number of polar groups and aromatic structures, their polymeric structure and low solubility in For all types of lubricating oils, lignosulfonates are not only suitable as thickener constituents but also as solid lubricants in lubricating greases and lubricating pastes. In addition, the sulfur content promotes the EP / AW effect in the lubricating greases and the phenolic structures provide an age-inhibiting effect.

It is believed that the lignosulfonate structure has a predominantly planar structure due to its large number of polymeric and polar aromatic units. Thus, under the action of external frictional and shear forces, these can deposit very well in layer structures on metal surfaces, because the aromatic nuclei of the lignin sulfonate interact in an associative manner with the metal surface and efficiently and permanently separate metallic friction partners even at high loads or pressures.

If calcium lignosulfonate is added even before the start of the reaction phase in the production of soap thickeners, in particular of calcium complex soaps, these on the one hand produce an additional thickening effect and a high dropping point and on the other hand they improve the wear protection and lubricating effects of corresponding grease formulations.

Therefore, it is beneficial for the distribution and effect of additives and solid lubricants, if they are chemically or mechanically integrated during the reaction phase as an additional structural element in situ in the thickener structure.

For the production of soap greases with high dripping points must in the prior art in many cases specially treated and expensive fatty acids such. B. 12-Hydroxistearinsäure or special complexing agents such. As borates or salts of acetic acid, sebacic acid and azelaic acid are used, which have no or only a small simultaneous effect as anti-wear and friction-reducing additive. By using Ca lignosulfonates, the use of said components can be reduced or even dispensed with. Furthermore, the use of Ca lignosulfonates offers the opportunity to formulate high performance lubricating fats based on renewable raw materials and to dispense with an environmentally harmful additive chemistry.

Thickening oils consisting of unmodified or slightly modified native fatty acid esters with metal soaps based on animal or vegetable fatty acids and lignosulfonates used as the only other thickener and simultaneous additive component, we obtain greases, except for the calcium hydroxide used for metal soaps exclusively based on renewable Raw materials were produced. These are resistant to aging and wear, as well as increasing the load stress and reducing friction by the use of lignosulfonates as thickener component.

The greases according to the invention are suitable for use in or for, rolling bearings and gearboxes, in particular constant velocity universal joint shafts which have at least one bellows, z. Example of thermoplastic elastomers (TPE) such as polyether esters (TPE-E) and chloroprenes. The best-known application of constant velocity universal joint shafts, sometimes called synchronizing shafts for short, are drive shafts on steered vehicle wheels, ie on driven front wheels. But the joints of other axle drive shafts are designed as constant velocity joints in modern vehicles. The homokinetic joint is a joint for uniform angular velocity and torque transmission from a shaft to an angularly mounted second shaft.

Suitable constant velocity universal joint shafts or types and their encapsulation or encapsulation materials are described in more detail below.

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, Undercut Free UJ Gauges The group of gearchange joints are Tripod Joints (TJ), Double Offset joints (Double offset joints "DOJ") and cross-cut compound joints ("Cross Groove Joins" LJ) In contrast to the constant velocity joints, constant velocity joints not only provide uniform torque transmission at different bend angles, but also provide length compensation of the drive shaft connecting the transmission 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.

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 comprising a thermoplastic copolyester elastomer Hard segments having crystalline properties and having a melting point above 100 ° C and soft segments having a glass transition temperature of less than 20 ° C, preferably less than 0 ° C.

Particularly suitable are polychloroprene rubber and thermoplastic polyesters (TPE), thermoplastic polyether esters (TEES = thematic ether-ester elastomer). The latter are available under the trade names Arnitel ^® from DSM, Hytrel ^® from DuPont and PIBI-Flex ^® P-Group in the market.

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 z. B. derived from at least one aliphatic diol or polyol and at least one aromatic di- or polycarboxylic acid, the soft segments with elastic properties z. B. from ether polymers such. As polyalkylene oxide glycols or non-aromatic dicarboxylic acids and allphatic diols. Such compounds are z. B. 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 for protecting drive shafts and transmission shafts, joint pillars 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.

As far as the base oils used from biodegradable esters such. As those containing predominantly renewable raw materials exist, the greases are also suitable for loss lubrication in the environmentally sensitive area (eg., In mining or agriculture).

In the particular case of lubrication maintenance-free constant velocity universal joint shafts was first formulated using calcium lignosulfonate a grease, which leads in contrast to the prior art entirely without MoS ₂ and other organic and inorganic molybdenum compounds to high lifetimes and good efficiencies.

In addition, the absence of other additives as Reibwertminderer, Fresslast- and wear protection causes a very good compatibility with many commercially available Kardwellenfaltenbalgmaterialien such as chloroprene rubber and thermoplastic polyether esters. Since the sulfur containing lignosulfonate is bound by thermally stable sulfonate groups, unlike the sulfur bound in conventional additives, it can only be released at very high temperatures or activation energies, such as occur in grease applications only with highly loaded tribocontacts. Thus, a subsequent vulcanization or crosslinking of rubber materials is largely prevented by sulfur released from the aged lubricant.

The use of calcium lignosulfonate in overbased excess calcium hydroxide grease formulation prevents free lignin sulfonic acid from exerting a hydrolytic effect on bellows materials such as thermoplastic polyether esters.

It is a particular aspect of the present invention to arrive at cost-optimized grease formulations for highly loaded lubrication points such as in particular in constant velocity joints, which have a good compatibility with bellows, constructed of z. As thermoplastic polyether esters (TPE) and chloroprenes (CR), while high efficiency, low wear and long life.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 85/05421 Al [0050]
• DE 3508718 A [0050]

Cited non-patent literature

• DIN 51807-1 (Issue: 1979-04) [0020]
• DIN 51807-2 (1990-03 edition) [0020]
• DIN ISO 2176 [0026]
• GE Fredheim, SM Braaten and BE Christensen, "Comparison of molecular weight and molecular weight distribution of softwood and hardwood lignosulfonate" published in the "Journal of Wood Chemistry and Technology", Vol. 23, No. 2, pp. 197-215, 2003 [ 0035]

Claims (22)

A process for producing lignosulfonate-containing greases comprising a) the step of bringing together at least: - a base oil A calcium soap, optionally in situ, having 10 or more carbon atoms, wherein when the calcium soaps are prepared in situ, at least calcium hydroxide is added, - complexing agent, Calcium lignosulfonate, preferably with weight average molecular weights of 10,000 g / mol and smaller, Heating to greater than 120 ° C for reaction and expulsion of low-boiling components to produce a base grease and b) the step of cooling and the addition of base oil and optionally additives with mixing. A method according to claim 1, characterized in that in step a) calcium hydroxide is added in addition to optionally further alkaline earth metal hydroxides. A method according to claim 1, characterized in that the grease is made alkaline, in particular by the addition of calcium hydroxide in excess. A method according to claim 1, characterized in that the heating to temperatures of greater than 180 ° C, takes place. A method according to claim 1, characterized in that in addition to calcium hydroxide in step a) and lithium hydroxide, magnesium hydroxide and / or aluminum hydroxide or aluminum alkoxides and / or Aluminiumoxoalkoholate and / or lithium, magnesium and / or aluminum soaps of a saturated or unsaturated mono-carboxylic acid 10 to 32 carbon atoms, optionally substituted, are used. A method according to claim 1, characterized in that the grease independently contains: - 55 to 92 wt .-%, in particular 70 to 85 wt .-%, of the base oil, - 0 to 40 wt .-%, in particular 2 to 10 wt. -%, additives, - 3 to 40 wt .-%, in particular 5 to 20 wt .-%, soaps and - 0.5 to 20 wt .-%, in particular 0.5 to 10 wt .-%, complexing agent, and - If necessary, excess Ca (OH) ₂ , preferably 0.01 to 2 wt .-%, - 0.5 to 45, in particular 2 to 15 wt .-%, and particularly preferably 4 to 8 wt .-% calcium lignosulfonate , optionally in addition to other Erdalkaliligninsulfonaten, each based on the total composition of the grease. A method according to claim 1, characterized in that the base fat of step a) can be produced by using - 40 to 70 wt .-%, in particular 45 to 60 wt .-%, of the base oil, - 10 to 60 wt .-%, in particular 15 to 50 wt .-%, soaps and - 1 to 30 wt .-%, in particular 5 to 20 wt .-%, complexing agent, and - optionally excess Ca (OH) ₂ , preferably 0.02 to 4 wt. %, - 0.7 to 50, especially 4 to 30 wt .-% calcium lignosulfonate, optionally in addition to other Erdalkaliligninsulfonaten, each based on the composition of the base fat. A method according to claim 1 or 4, characterized in that the grease contains independently from 0.2 to 5 wt .-% graphite and / or no solid lubricant or less <1 wt .-% solid lubricant, in particular no MoS ₂ . A method according to claim 1, characterized in that the calcium soap is prepared in situ as a reaction product of calcium hydroxide, with a saturated or unsaturated mono-carboxylic acid having 10 to 32 carbon atoms, in particular having 16 to 20 carbon atoms, optionally substituted z. B. by hydroxy, as an ester or anhydride. A method according to claim 1, characterized in that the complexing agent as a reaction product of a calcium salt, in particular calcium hydroxide, with a saturated or unsaturated mono-carboxylic acid having 2 to 8, in particular 2 to 4, carbon atoms or a di-carboxylic acid having 2 to 16, in particular 2 to 12 carbon atoms, each optionally substituted, e.g. B. by hydroxy, as an ester or anhydride, while step a) is added. A method according to claim 1, characterized in that the complexing agent is a calcium salt of a carboxylic acid and in situ during step a) by adding a saturated or unsaturated mono-carboxylic acid having 2 to 8, in particular 2 to 4, carbon atoms or a di-carboxylic acid 2 to 16, in particular 2 to 12 carbon atoms, in each case optionally substituted, for. B. by hydroxy, is prepared as an ester or anhydride. A method according to any one of claims 1 to 11, characterized in that the calcium lignosulfonate is dehydrated prior to addition to values of less than 0.5% by weight of water, e.g. B. by heating in the base oil to about 95 ° C, especially about 100 ° C to z. B. 120 ° C. Method according to at least one of claims 1 to 12, characterized in that the composition contains complexing agent to 0.5 to 20 wt .-%, in particular 0.5 to 10 wt .-%. Lubricating grease composition comprising - 55 to 92 wt .-%, in particular 70 to 85 wt .-%, of the base oil, - 0 to 40 wt .-%, in particular 2 to 10 wt .-%, additives, - 3 to 40 wt .-%, in particular 5 to 20 wt .-%, calcium soaps having 10 and more carbon atoms, - 0.5 to 20 wt .-%, in particular 0.5 to 10 wt .-%, complexing agent, and - optionally excess Ca (OH) _2, preferably 0.01 to 2 wt .-%, - 0.5 to 50, in particular 2 to 15 wt .-% and particularly 2 to 8 wt .- Favor% calcium lignosulfonate, possibly among other Erdalkaliligninsulfonaten, each based on the total composition of the grease. A composition according to claim 14, 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. Composition according to at least one of Claims 14 or 15, characterized in that the base oil has a kinematic viscosity of 20 to 2500 mm ² / s, preferably 40 to 500 mm ² / s, at 40 ° C. Composition according to at least one of Claims 14 to 16, characterized in that the complexing agent consists of: - An alkali metal salt, preferably lithium salt, alkaline earth metal salt, preferably calcium salts, or aluminum salt of a saturated or unsaturated mono-carboxylic acid having 2 to 8, especially 2 to 4, carbon atoms or a di-carboxylic acid having 2 to 16, especially 2 to 12 carbon atoms, in each case optionally substituted. Composition according to at least one of Claims 14 to 17, characterized in that the additive comprises one or more members selected from the following group: Antioxidants such as amine compounds, phenolic compounds, sulfur dioxide antioxidants, zinc dithiocarbamate or zinc dithiophosphate; High pressure additives such as organic chlorine compounds, sulfur, phosphorus or calcium borate, zinc dithiophosphate, organic bismuth compounds; C2 to C6 polyols, fatty acids, fatty acid esters or animal or vegetable oils; Anticorrosion 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; Antiwear additives such as molybdenum di-alkyl dithiocarbamates or molybdenum sulfide di-alkyl dithiocarbamates, aromatic amines; - Friction modifier such as functional polymers such. Oleylamides, polyether- and amide-based organic compounds or molybdenum dithiocarbamate, and - Solid lubricants such. As polymer powder 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. As calcium carbonate, sodium and calcium phosphates. Composition according to at least one of claims 14 to 18, characterized in that the grease is water-resistant, namely a) according to the test according to DIN 51807-1 of the evaluation level 1-90 and / or b) according to the test according to DIN 51807-2 of the evaluation level 1-80. Use of the composition according to at least one of claims 14 to 19 for the lubrication of at least one constant-velocity joint, in particular as part of homokinetic propeller shafts and particularly preferably have a bellows. Constant speed joint shaft comprising the grease composition according to one of claims 14 to 19 at least one lubrication point, characterized in that the constant velocity joint has an encapsulation in the region of the lubrication point, wherein the encapsulation is preferably a bellows. A constant velocity universal joint according to claim 21, characterized in that the material of the encapsulation or of the bellows is or contains a thermoplastic elastomer, a polychloroprene, fluororubber or silicone, in particular a polyetherester.