EP4176027B1 - Polyurea greases containing carbonates and their use - Google Patents

Description

The invention relates to polyurea grease compositions containing polyurea thickeners and at least one organic carbonate, lubrication points or components containing the polyurea grease composition and a seal comprising a sealing material made of fluorinated elastomers and the use of the greases.

Introduction and state of the art

For tribosystems, as they are 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 area of application, lubricants of different consistencies can be used. Lubricating oils have a liquid and flowable consistency, while lubricating greases have a semi-solid to solid - often gel-like - consistency.

The characteristic of a lubricating grease is that a liquid oil component is absorbed and held by a thickener component. The pasty nature of a lubricating grease and its properties of being spreadable and easily plastically deformable, together with the properties of being adhesive, ensure that the lubricating grease wets the lubricating point and the lubricating effect develops on the tribologically stressed surfaces. In addition to additives, lubricating greases essentially include a thickener that is distributed in a base oil.

The most important rheological properties of a lubricating grease include its consistency or its yield point, the avoidance of post-hardening and excessive oil separation under thermal and mechanical stress, as well as stable viscosity-temperature behavior and viscosity-shear behavior. In order to create a lubricating grease of high utility value depending on the application requirements, a high degree of practical experience is required.

Greases are often used in encapsulated or sealed environments to protect the lubrication point from water, minimize grease loss and prevent entry of particles such as sand or dust. Typical applications for lubricating greases are the lubrication of rolling bearings, plain bearings, gears or constant velocity joint shafts. Polyurea lubricating greases are often used for lubrication points that are exposed to high temperatures and/or aggressive environments. If sealing materials are used under such operating conditions, fluorinated elastomers that are particularly thermally and chemically resilient are often used when selecting the sealing material. The combination of such a lubricating grease/sealing material pairing is often limited because the fluorinated elastomers tend to harden and even become brittle in the presence of the polyurea lubricating greases.

US20150299608 A1 describes a polyurea lubricating grease and its elastomer compatibility.

Various additives have been proposed to improve compatibility with fluorinated elastomers. examples for this are EP0562062 B1 , WO2012082285 A1 ; US10106759 ; US10066186 ; US10106759 ; US20150291906 A1 ; US10066186 , US20160002560 A1 and EP3374479 A1 .

Carbonates such as ethylene carbonate ( CN107903987 A ) or propylene carbonate ( US4298481 A ) are known in lubricating greases as an activator/dispersant for inorganic thickeners, but not as an additive for polyurea thickeners.

Task of the invention

The object of the present invention is to improve the performance properties of polyurea lubricating greases, for example with regard to consistency, shear stability and service life and in particular the lubricating grease should not post-harden or post-harden as little as possible. Furthermore, polyurea lubricating greases should be made available which have improved compatibility with fluorinated elastomers, such as those used as sealing materials, whereby the lubricating grease's performance properties should not be negatively influenced by any additives to increase compatibility with fluorinated elastomers.

Summary of the invention

The task is solved by the subject matter of the independent claims. Preferred embodiments are the subject of the subclaims or described below.

1. a) ein Grundöl (umfassend ggf. eine Grundölmischung) in einer Menge von 55 bis 95 Gew.% und vorzugsweise 70 bis 90 Gew.%;
2. b) zumindest einen Polyharnstoff-Verdicker in einer Menge von 1 bis 20 Gew%, vorzugsweise 1,5 bis 15 Gew.%;
3. c) zumindest ein organisches Carbonat, wobei das organische Carbonat 4 bis 8 Kohlenstoffatome aufweist in einer Menge von 0,1 bis 10 Gew%, vorzugsweise 0,2 bis 5 Gew.%, besonders bevorzugt 0,5 bis 2 Gew%.

The polyurea fat composition according to the invention comprises:

1. a) a base oil (optionally comprising a base oil mixture) in an amount of 55 to 95% by weight and preferably 70 to 90% by weight;
2. b) at least one polyurea thickener in an amount of 1 to 20% by weight, preferably 1.5 to 15% by weight;
3. c) at least one organic carbonate, the organic carbonate having 4 to 8 carbon atoms in an amount of 0.1 to 10% by weight, preferably 0.2 to 5% by weight, particularly preferably 0.5 to 2% by weight.

Furthermore, additives can be used beyond c), such as:
d) at least one additive, preferably in an amount of 0.5 to 40% by weight and in particular 2 to 10% by weight.

The polyurea fat composition optionally further contains 1 to 20% by weight, preferably 1 to 15% by weight, of a further thickener based on a soap and/or complex soap thickener.

Mixed fats containing polyurea thickeners and soap and/or complex soap thickeners are also referred to herein as polyurea fat compositions.

The terms polyurea fat composition and polyurea fat(s) are used synonymously below.

Detailed description of the invention

Common lubricating oils that are liquid at room temperature are suitable as base oils. The base oil preferably has a kinematic viscosity of 20 to 2500 mm ² /s, in particular 40 to 500 mm ² /s, in each case at 40 °C.

The base oils can be classified as mineral oils or synthetic oils. Mineral oils include, for example, naphthenic-based mineral oils and paraffin-based mineral oils, classified according to API Group I. Chemically modified aromatic and low-sulfur mineral oils with a low proportion of saturated compounds and improved viscosity/temperature behavior compared to Group I oils, classified according to API Group II and III, are also suitable.

Synthetic oils that may be mentioned include, in particular, polyethers, esters, polyalphaolefins, polyglycols and alkyl aromatics and mixtures thereof, as well as silicone oils. The polyether compound can have free hydroxyl groups, but can also be completely etherified or end groups esterified and/or made from a starting compound with one or more hydroxyl and/or carboxyl groups (-COOH). Polyphenyl ethers, possibly alkylated, are also possible as sole components or, better yet, as mixed components. Suitable for use are esters of an aromatic di-, tri- or tetracarboxylic acid, with one or in a mixture of C2 to C22 alcohols, esters of adipic acid, sebacic acid, trimethylolopropane, 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 mixture.

The polyurea thickeners are organic thickener systems which are obtainable by reacting one or more amine components with one or more isocyanate components.

The starting materials for producing the polyurea thickener(s) are primary amines and isocyanates.

The amines are monoaminohydrocarbyl, di- or polyaminohydrocarbylene compounds. The hydrocarbyl or hydrocarbylene groups each preferably have 6 to 20 carbon atoms, particularly preferably 6 to 15 carbon atoms. The hydrocarbylene group preferably has aliphatic groups, in particular alkyl or alkylene groups. Suitable amines or suitable polyureas are, for example, in EP 0508115 A1 from page 1, line 51 to page 16 mentioned below.

Mono- and/or polyisocyanates are suitable as isocyanate components, the polyisocyanates preferably being hydrocarbons with two isocyanate groups. The isocyanates have 5 to 20, preferably 6 to 15, carbons and preferably contain aromatic groups.

Either the amine component is mono-, di- or polyfunctional or the isocyanate component is mono-, di- or polyfunctional or both.

According to one embodiment, the polyurea thickeners are available as a reaction product of diisocyanates with C6 to C20 hydrocarbyl monoamines. However, the reaction products of mono-isocyanates, possibly plus additional diisocyanates, with diamines can also be present. The polyurea thickeners typically do not have a polymeric character, but are, for example, dimers, trimers or tetramers. In addition to the polyisocyanates, isocyanates of the type R-NCO (monoisocyanates) can also be used, where R represents a hydrocarbon radical with preferably 5 to 20 carbon atoms.

• Diharnstoffe auf Basis von 4,4'-Diphenylmethandiisocyanat (MDI) oder Toluol-2,4-diisocyanat (TDI) und aliphatischen, aromatischen und/oder cyclischen primären Mono-Aminen oder
• Tetraharnstoffe auf Basis von MDI oder TDI und aliphatischen, aromatischen und/oder cyclischen Mono- und Diaminen.

Diureas obtainable from diisocyanates and monoamines or tetraureas obtainable from diisocyanates, monoamine and diamine, each as defined above, are preferred. Are particularly preferred

• Diureas based on 4,4'-diphenylmethane diisocyanate (MDI) or toluene 2,4-diisocyanate (TDI) and aliphatic, aromatic and/or cyclic primary mono-amines or
• Tetraureas based on MDI or TDI and aliphatic, aromatic and/or cyclic mono- and diamines.

The polyurea thickener is preferably prepared by in-situ reaction of the amine and isocyanate components in the base oil.

Optionally, additional inorganic thickeners can be bentonites, such as montmorillonite (the sodium ions of which may be exchanged or partially exchanged by organically modified ammonium ions), aluminosilicates, clays, hydrophobic and hydrophilic silica, if necessary together with oil-soluble polymers (e.g. polyolefins, poly( meth)acrylates, polyisobutylenes, polybutenes or polystyrene copolymers) can be used as co-thickeners.

The bentonites, aluminosilicates, clays, silica, amorphous silicon dioxide and/or oil-soluble polymers can be added to produce the base fat or added later as an additive in the second step. Preferably no inorganic thickeners are used, in particular no bentonites, aluminosilicates, clays, silica, and amorphous silicon dioxide, each individually.

Soap or complex soap thickeners based on calcium, lithium or aluminum salts are particularly suitable as organic thickeners. The soap is available, for example, as a reaction product of, for example, calcium hydroxide, lithium hydroxide or aluminum alkoxide with a saturated or unsaturated monocarboxylic acid with 10 to 32 carbon atoms, in particular with 16 to 20 carbon atoms, optionally substituted, for example by hydroxy, as an ester or anhydride. Esterified dicarboxylic acid semiamides (C12 - C24) based on terephthalic acid can also be used. The corresponding fats are also called soap thickeners here. The soap becomes a complex soap due to the presence of a complexing agent. Suitable complexing agents are: (a) the alkali metal salt (preferably lithium salt), alkaline earth metal salt (preferably calcium salt) or aluminum salt of a saturated or unsaturated mono-carboxylic acid or also hydroxycarboxylic acids with 2 to 8, in particular 2 to 4 carbon atoms or a di-carboxylic acid with 2 to 16 , in particular 2 to 12 carbon atoms, each optionally substituted, and/or (b) the alkali metal 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 .

Simple, mixed or complex soaps based on Li, Na, Mg, Ca, Al, Ti salts and carboxylic acids or sulfonic acids can be added during base fat production or later as an additive. Alternatively, these soaps can also be formed in situ during the production of the fats.

For example, stearate benzoate hydroxyaluminates can be used to produce aluminum complex soap-thickened lubricating greases. Lithium 12-hydroxystearate thickeners are typical representatives of lithium soap fats, calcium 12-hydroxystearate thickeners are typical for calcium soap fats.

According to a preferred alternative, the polyurea thickener and the soap or complex soap thickener are used together, with Ca soaps or Ca complex soaps being particularly preferred, for example in a mixing ratio of 10:1 to 1:10, in particular 5:1 to 1 : 5 (each mass : mass). Soap or complex soap thickeners and polyurea thickeners are then preferably used together at 5 to 25% by weight based on the polyurea fat composition of claim 1, the polyurea thickener being used at least 1% by weight, preferably at least 1%. 5% by weight, each based on the polyurea fat composition.

Polymer powders such as polyamides, polyimides or PTFE, melamine cyanurate, graphite, metal oxides, boron nitride, silicates, e.g. magnesium silicate hydrate (talc), sodium tetraborate, potassium tetraborate, metal sulfides such as e.g. B. molybdenum disulfide, tungsten disulfide or mixed sulfides based on tungsten, molybdenum, bismuth, tin and zinc, inorganic salts, for example of alkali and alkaline earth metals, such as calcium carbonate, sodium and calcium phosphates, can be used. Likewise soot or other carbon-based solid lubricants such as nanotubes.

Likewise, lignin derivatives, such as alkali metal or alkaline earth metal lignin sulfonates, in particular calcium lignin sulfonates, can be used to achieve specific properties, for example 2 to 15% by weight (according to WO2011095155A1 or US 8507421 B2 ).

In the context of the present invention, it was surprisingly found that the addition of the claimed organic carbonates improves the performance properties of the polyurea lubricating greases according to the invention, and the compatibility of polyurea lubricating greases with fluorinated elastomers is improved by using organic carbonates.

The organic carbonates have 4 to 8 carbon atoms. The residues or components of the organic carbonates are hydrocarbons (apart from the carbonate group itself), that is, the organic carbonate is not heteroatom-substituted.

Cyclic carbonates, in particular with 4 to 8, in particular 4 or 5 carbon atoms, are preferred. Examples are diethyl carbonate, methyl ethyl carbonate; Dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, diisobutyl carbonate,. Examples of cyclic organic carbonates that can be used are propylene carbonate (4-methyl-1,3-dioxolan-2-one), 2,3-butylene carbonate (4,5-dimethyl-1,3-dioxolan-2-one) or 1, 2-Butylene carbonate (4-ethyl-1,3-dioxolan-2-one), hexahydro-1,3-benzodioxol-2-one or 1,3-benzodioxol-2-one can be used, with propylene carbonate being preferably used.

The organic cyclic carbonate can be added to the polyurea fat as an additive during production, but preferably after the thickener system has been completely formed in the cooling phase.

In addition, the lubricating grease compositions according to the invention contain customary additives against corrosion, oxidation and for protection against metal influences, which act as chelate compounds, radical scavengers, reaction layer formers and the like. Additives that improve the hydrolysis resistance of ester base oils, such as carbodiimides or epoxides, can also be added.

• primäre Antioxidationsmittel wie Amin-Verbindungen (z.B. Alkylamine oder 1-Phenylaminonaphthalin), aromatische Amine, wie z.B. Phenylnaphtylamine oder Diphenylamine oder polymere Hydroxychinoline (z. B. TMQ), Phenol-Verbindungen (z.B. 2.6-Di-tert-butyl-4-methylphenol), Zinkdithiocarbamat oder Zinkdithiophosphat;
• sekundäre Antioxidationsmittel wie Phosphite, z.B. Tris(2,4-ditert-butylphenylphosphit) oder Bis(2,4-ditert-butylphenyl)-pentaerythritoldiphosphit oder Thioether (z.B. Kresolthioether);
• Hochdruckadditive und/oder Verschleißschutzadditive wie Schwefel oder organische Schwefelverbindungen wie z.B. Polysulfide oder geschwefelte Olefine, überbasische Calciumsulfonate, Thiophosphate, Phosphorverbindungen wie z.B. aminneutralisierte Alkylphosphate;
• anorganische oder organische Borverbindungen, Zinkdialkyldithiophosphat, organische Bismuthverbindungen; Thiophosphonate wie z.B. Triphenylthiophosphat, Phosphonate (Phosphite) wie z.B. Dioctylphosphonat, Alkylsulfonate, Thiocarbamate wie z.B. Methylen-bis(dibutyldithiocarbamate und Dithiocarbamate.
• Die "Öligkeit" verbessernde Wirkstoffe wie C2- bis C6- Polyole, Fettsäuren, Fettsäureester oder tierische oder pflanzliche Öle;
• Antikorrosionsmittel wie Sulfonate wie z.B. Petroleumsulfonat, Dinonylnaphtalinsulfonat oder Sorbitanester; neutrale oder überbasische Calciumsulfonate, Magnesiumsulfonate, Natriumsulfonate, Calcium- und Natrium-Naphthalinsulfonate, Sulfonsäureester, Dinatriumsebacat, Calcium-Salicylate, Aminphosphate, Succinate;
• Metalldeaktivatoren wie Benzotriazole wie z.B. Methylbenzotriazoldialkylamin, sterisch gehinderte Phenole, Natriumnitrit;
• Viskositätsverbesserer wie z.B. Polymethacrylat, Polyisobutylen, oligo Dec-1-ene, Polystyrole;
• Reibungsminderer teilweise mit Verschleißschutzeigenschaften wie Organomolybdänkomplexe (OMC), Molybdän-di-alkyl-dithiophosphate, Molybdän-di-alkyldithiocarbamate, insbesondere Molybdän-di-n-butyldithiocarbamat und Molybdän-di-alkyldithiocarbamat (Mo_2mS_n(dialkylcarbamat)₂ mit m = 0 bis 3 und n = 4 bis 1), Zinkdithiocarbamat oder Zinkdithiophosphat; oder eine dreikernige Molybdänverbindung, die der Formel
  
          Mo₃S_kL_nQ_z
  
  entspricht, in der L unabhängig ausgewählte Liganden sind, die Organogruppen mit Kohlenstoffatomen aufweisen, wie sie in der US 6172013 B1 offenbart sind, um die Verbindung in dem Öl löslich oder dispergierbar zu machen, wobei n von 1 bis 4 reicht, k von 4 bis 7 reicht, Q aus der Gruppe von neutralen Elektronendonator-Verbindungen, bestehend aus Aminen, Alkoholen, Phosphinen und Ethern, ausgewählt ist, und z im Bereich von 0 bis 5 liegt und nicht-stöchiometrische Werte umfasst (vergleiche DE 102007048091 );_organische Säuren wie z.B. Isostearinsäure, funktionelle Polymere wie z.B. Oleylamide, organische Verbindungen auf Polyether- und Amidbasis, z.B. Alkylpolyethylenglykoltetradecylenglykolether, PIBSI (Polyisobutylenbernsteinsäureimid) oder PIBSA (Polyisobutylenbernsteinsäureanhydrid), Partialglyceride, Dialkylhydrogenphosphonate, Alkylsuccinate.

Common additives within the meaning of the invention are antioxidants, anti-wear agents, anti-corrosion agents, detergents, dyes, lubricity improvers, adhesion improvers, viscosity additives, friction reducers, high-pressure additives and metal deactivators. Examples include:

• primary antioxidants such as amine compounds (e.g. alkylamines or 1-phenylamino-naphthalene), aromatic amines such as phenylnaphtylamines or diphenylamines or polymeric hydroxyquinolines (e.g. TMQ), phenol compounds (e.g. 2.6-di-tert-butyl-4-methylphenol ), zinc dithiocarbamate or zinc dithiophosphate;
• secondary antioxidants such as phosphites, for example tris(2,4-ditert-butylphenyl phosphite) or bis(2,4-ditert-butylphenyl) pentaerythritol diphosphite or thioethers (for example cresol thioether);
• High-pressure additives and/or anti-wear additives such as sulfur or organic sulfur compounds such as polysulfides or sulfurized olefins, overbased calcium sulfonates, thiophosphates, phosphorus compounds such as amine-neutralized alkyl phosphates;
• inorganic or organic boron compounds, zinc dialkyldithiophosphate, organic bismuth compounds; Thiophosphonates such as triphenylthiophosphate, phosphonates (phosphites) such as dioctyl phosphonate, alkyl sulfonates, thiocarbamates such as methylene bis(dibutyldithiocarbamates and dithiocarbamates.
• Active ingredients that improve "oiliness" such as C2 to C6 polyols, fatty acids, fatty acid esters or animal or vegetable oils;
• anticorrosion agents such as sulfonates such as petroleum sulfonate, dinonyl naphthalene sulfonate or sorbitan esters; neutral or overbased calcium sulfonates, magnesium sulfonates, sodium sulfonates, calcium and sodium naphthalene sulfonates, sulfonic acid esters, disodium sebacate, calcium salicylates, amine phosphates, succinates;
• Metal deactivators such as benzotriazoles such as methylbenzotriazole dialkylamine, sterically hindered phenols, sodium nitrite;
• Viscosity improvers such as polymethacrylate, polyisobutylene, oligo dec-1-ene, polystyrenes;
• Friction reducers partly with wear protection properties such as organomolybdenum complexes (OMC), molybdenum di-alkyl dithiophosphates, molybdenum di-alkyldithiocarbamates, in particular molybdenum di-n-butyldithiocarbamate and molybdenum di-alkyldithiocarbamate (Mo _2m S _n (dialkyl carbamate) ₂ with m = 0 to 3 and n = 4 to 1), zinc dithiocarbamate or zinc dithiophosphate; or a trinuclear molybdenum compound having the formula
  
  Mo ₃ S _k L _n Q _z
  
  corresponds, in which L are independently selected ligands which have organogroups with carbon atoms, as in the US 6172013 B1 are disclosed to make the compound soluble or dispersible in the oil, where n ranges from 1 to 4, k ranges from 4 to 7, Q from the group of neutral electron donor compounds consisting of amines, alcohols, phosphines and ethers, is selected, and z is in the range from 0 to 5 and includes non-stoichiometric values (compare DE 102007048091 );_Organic acids such as isostearic acid, functional polymers such as oleylamides, organic compounds based on polyethers and amides, e.g. alkyl polyethylene glycol tetradecylene glycol ether, PIBSI (polyisobutylene succinic acid imide) or PIBSA (polyisobutylene succinic anhydride), partial glycerides, dialkyl hydrogen phosphonates, alkyl succinates.

1. a) 55 bis 95 Gew.% insbesondere 70 bis 90 Gew.%, des Grundöls;
2. b) 1 bis 20 Gew.%, insbesondere 1,5 bis 15 Gew.%, des Polyharnstoffverdickers;
3. c) 0,1 bis 10 Gew.%, insbesondere 0,2 bis 5 Gew.%, besonders bevorzugt 0,5 bis 2 Gew.%, der organischen Carbonate;

und aus folgenden fakultativen Komponenten:

• d) 0,5 bis 40 Gew.%, insbesondere 2 bis 10 Gew.%, Additive;
• e) 0 bis 20 Gew.%, insbesondere 0 bis 5 Gew.%, anorganische Verdicker, wie amorphes SiO₂ bzw. Kieselsäure; und
• f) 0 bis 20 Gew.%, insbesondere 0,1 bis 15 Gew.%, Festschmierstoffe
• g) 0 bis 20 Gew.%, insbesondere 1 bis 15%, weitere organische Verdicker, insbesondere Seifen- oder Komplexseifenverdicker auf Basis von Calcium-, Lithium- oder Aluminiumseifen

neben etwaigen weiteren Komponenten wie Lignin-Derivaten.The polyurea fat compositions are structured in particular as follows:

1. a) 55 to 95% by weight, in particular 70 to 90% by weight, of the base oil;
2. b) 1 to 20% by weight, in particular 1.5 to 15% by weight, of the polyurea thickener;
3. c) 0.1 to 10% by weight, in particular 0.2 to 5% by weight, particularly preferably 0.5 to 2% by weight, of the organic carbonates;

and the following optional components:

• d) 0.5 to 40% by weight, in particular 2 to 10% by weight, of additives;
• e) 0 to 20% by weight, in particular 0 to 5% by weight, of inorganic thickeners, such as amorphous SiO ₂ or silica; and
• f) 0 to 20% by weight, in particular 0.1 to 15% by weight, of solid lubricants
• g) 0 to 20% by weight, in particular 1 to 15%, of further organic thickeners, in particular soap or complex soap thickeners based on calcium, lithium or aluminum soaps

in addition to any other components such as lignin derivatives.

The wt.% information refers to the overall composition and applies independently of each other. A component that is assigned to one of the groups a), b), c) or d) cannot simultaneously be a component of another group a) to d). The wt.% information adds up to 100 wt.% for each selection of components, including any optional components not mentioned above.

In particular, the thickener is used in such a way that the composition contains so much thickener that a cone penetration value (rolled penetration) of 220 to 430 mm/10 (at 25 ° C), preferably 265 to 385 mm/10, is obtained (determined according to DIN ISO 2137).

The polyurea in the polyurea grease composition is generally produced by in situ reaction of the above-mentioned amines and isocyanates, preferably in the base oil.

• Grundöl und Amin- und Isocyanat-Komponenten und
• Erhitzen über 120°C, insbesondere über 150°C, zur Herstellung des Basisfettes,
• Abkühlen des Basisfettes und Zugabe der Additive, vorzugsweise bei unter 100°C oder sogar unter 80°C.

According to the process for producing the polyurea fat composition on which the present invention is based, a precursor (base fat) is first created by combining at least

• Base oil and amine and isocyanate components and
• Heating above 120°C, in particular above 150°C, to produce the base fat,
• Cooling the base fat and adding the additives, preferably at below 100°C or even below 80°C.

If a further thickener component is added to the polyurea base fat, such as the soap or complex soap thickener, this is done, for example, after the base fat has been produced during the cooling curve at a suitable temperature (e.g. at 140 to 115 ° C. Addition of the soap or complex soap thickener, in particular the Ca- soap or the Ca complex soap).

To produce the base fat, the base fat is preferably heated to temperatures of over 120°C or, better, greater than 150°C. 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, the formation of the thickener structure is completed by cooling and, if necessary, additional components such as additives and/or base oil are added to set the desired consistency or the desired property profile. The second step can be carried out in the reactor of the first step, but preferably the base fat is transferred from the reactor into a separate stirred tank for cooling and mixing in any additional components.

What applies to pure polyurea fats can also be transferred to mixed thickener systems with polyurea thickener content. The production of polyurea fats with lime soap content (simple and complex soaps of hydroxymonocarboxylic acids, e.g. 12-hydroxystearic acid) is, for example, in US 5084193 disclosed. The procedure of US 5084193 can also be used to produce the polyurea fats according to the invention.

The lubricating greases according to the invention are particularly suitable for use in or for plain bearings, roller bearings, gears or constant velocity joint shafts. The lubricating greases according to the invention, containing predominantly polyurea thickeners as thickeners, are particularly suitable as high-temperature greases.

It is a particular aspect of the present invention to provide a grease that is compatible with fluorinated elastomer sealing materials. The selection of fluorinated elastomers as materials for seals of various designs is often dictated by the operating conditions such as high temperatures and/or chemically aggressive media, as these materials have exceptional resistance to heat, weather conditions and numerous chemicals.

Fluororubbers (often abbreviated as FKM or FPM) belong to the class of fluorinated elastomers. Depending on the desired fluoroelastomer properties, diamine, bisphenolic or peroxidic crosslinks are used for crosslinking. Fluororubbers are rubbers that have vinylidene (di)fluoride (VDF) as one of their monomers as a common feature. The two main types of fluororubbers are copolymers of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) and terpolymers of VDF, HFP and tetrafluoroethylene (TFE). Typical commercial products for fluororubbers are sold under the brands Viton ^® , Tecnoflon ^® , Dyneon ^® or Dai-El ^® . distributed.

There are also polymers made from VDF, HFP, TFE and perfluoromethyl vinyl ether (PMVE), polymers made from VDF, TFE and propene, as well as polymers made from VDF, HFP, TFE, PMVE and ethers.

In addition to fluororubbers, there are other groups of fluorinated elastomers, such as: E.g. perfluoro rubber (FFKM), tetrafluoroethylene/propylene rubbers (FEPM) and fluorinated silicone rubbers (FVMQ).

The sealing materials are used in the form or as part of seals at the lubrication points where the polyurea grease is used. Seals are a widely differentiated class of important construction elements.

In principle, sealing points can be divided into static and dynamic. Lubrication is particularly necessary for moving parts, so seals often refer to dynamic sealing points. But the static housing seal, e.g. of gearboxes as leakage protection, is also included as an example of static seals.

The seals are designed, for example, as O-rings or profile rings, radial shaft seals, mechanical seals, stuffing box seals, flat seals, lip seals, wipers, sealing cords. Examples of applications include radial shaft seals for generator shafts, stuffing box seals for pumps, mechanical seals for chemical reactors or bead mills (sealing the stirrer shaft), shaft seals in dryers, screw conveyors and conveyor belts, sealing elements for hydraulic and pneumatic systems (presses, construction vehicles, etc.) and Seals for rolling bearings and plain bearings.

The invention is explained below using examples without being limited to them. The details of the examples and the properties of the lubricating greases are shown in Tables 1 to 5 below.

Example 1: Production of fats B1-A to B1-C

630 g of Group II oil (hard hydrogenated, paraffinic; 105-110 cSt at 40 ° C) were placed in a heatable reaction vessel with a stirrer. To this were added 113.4 g of 4,4-methylene-bis-diphenyl diisocyanate and the contents of the reaction vessel were heated to 60 ° C with stirring. 630g of PAO 8 were placed in another heatable vessel with a stirrer and 87.6g of p-toluidine and 9.0g of cyclohexylamine were added. The contents of the vessel were heated to 60°C. The contents of this vessel were transferred to the reaction vessel with dissolved isocyanate. The thickener was formed in an exothermic reaction. The thickener-oil mixture was then heated to a final temperature of 160 ° C over the course of 2 hours. After the reaction mixture had cooled to a temperature of 100 ° C, 15.0 g of Irganox L101 and 15.0 g of Irganox L115 were added. The mixture was cooled to 60 ° C and the desired amount of propylene carbonate (0 - 1% by weight) was added. Finally, the lubricating grease was homogenized using a colloid mill. <i>Table 1</i> Designation B1-A B1-B B1-C Propylene carbonate 0% 0.5% 1.0% Δ Shore A +15 +11 +2 Δ weight +1.2% +1.3% +1.1% Δ volume +3.2% +2.8% +0.9%

Example 2: Production of fats B2-A to B2-C

1305.0 g of group I oil (mineral oil, paraffinic; 110 cSt at 40 ° C) were placed in a heatable reaction vessel with a stirrer and 88.5 g of 4,4-methylene-bis-diphenyl diisocyanate were added. The contents of the reaction vessel were heated to 60 ° C with stirring. 91.5 g of n-octylamine were then added dropwise to the contents of the reaction vessel. An exothermic reaction took place with the formation of the thickener. The reaction mixture was heated to a final temperature of 160 ° C within 2 hours with stirring and then cooled to 60 ° C. The desired amount of propylene carbonate (0-1% by weight) was then added and the fat was finally homogenized using a colloid mill. The properties of the polyurea grease obtained are summarized in Table 2. <i>Table 2</i> Designation B2-A B2-B B2-C Propylene carbonate - 0.5% 1% Δ Shore A +13 +7 +3 Δ weight +3.6% + 1.6% +1.9% Δ volume +8.2% +3.4% +5.0%

Example 3: Production of fats B3-A to B3-C

369.7g of Group I oil (paraffinic; 480cSt at 40°C) and 567.2g of Group II oil (hard hydrogenated, paraffinic; 105-110cSt at 40°C) were placed in a heatable reaction vessel with a stirrer.

To this were added 94.2 g of 4,4-methylene-bis-diphenyl diisocyanate and the contents of the reaction vessel were heated to 60 ° C while stirring. A mixture of 37.3 g of cyclohexylamine and 47.8 g of n-octylamine was then added dropwise, whereupon the thickener was formed exothermically. The reaction mixture was heated to a final temperature of 160 ° C within two hours with stirring. When the final temperature of 160 ° C was reached, a further 300.0 g of Group II oil (hard hydrogenated, paraffinic; 105-110 cSt at 40 ° C) were added and then the reaction mixture was cooled to 130 ° C and 44.8 g of calcium 12-hydroxystearate were added . The temperature of 130°C was maintained for 30 minutes. The reaction mixture was then cooled to 110 ° C, 7.5 g of a phenolic antioxidant (Irganox L115) and 31.5 g of inorganic filler were added. After cooling to 60 ° C, the desired amount of propylene carbonate (0-1% by weight) was added. An additive package consisting of amine antioxidants, high-pressure additives, AW additives, non-ferrous metal passivators and corrosion protection additives was then added and the grease was finally homogenized using a three-roll mill.

The properties of the polyurea grease obtained containing calcium soap are summarized in Table 3. The dropping point was determined according to DIN ISO 2176. <i>Table 3</i> B3-A B3-B B3-C Propylene carbonate 0% 0.3% 1% RP-SF 253 281 273 RP-24h 233 239 242 WP60 272 289 286 WP60000 285 304 294 ΔP 60-60000 13 15 8th Dropping point 272.7°C 270.0°C 264.2°C Δ Shore A +8 +4 +1 Δ weight +1.7% + 1.6% +1.7% Δ volume +2.6% + 0.6% +2.6%

Determination of compatibility with fluorinated elastomers

The compatibility of polyurea greases with fluorinated elastomers is determined using a vinylidene fluoride-hexafluoropropylene copolymer (Type: SRE-FKM/2X according to DIN ISO 13226). For this purpose, test specimens with a diameter of 30mm and a thickness of 2mm were punched out of an elastomer plate made of SRE-FKM/2X. The test specimens were stored in the polyurea fats described above at 180°C or 160°C for 7 days and then evaluated.

1. a) Bestimmung der Eindringhärte (Shore A) nach DIN EN ISO 7619-1, wobei der Prüfkörper vor der Behandlung eine Eindringhärte (Shore A) von 78 aufwies, und
2. b) Biegeversuche von Hand.

The evaluation of the fluorinated elastomers was carried out after wiping off the grease with a clean cloth by:

1. a) Determination of the penetration hardness (Shore A) according to DIN EN ISO 7619-1, where the test specimen had a penetration hardness (Shore A) of 78 before treatment, and
2. b) Bending tests by hand.

The bending tests were carried out by bending the elastomer over a tube with a diameter of 3cm and 1cm. The elasticity of the elastomer was evaluated.

The stabilizing effect of propylene carbonate was demonstrated in the storage test. As the propylene carbonate content increased, there were no or only slight signs of brittleness despite the high storage temperature of 180°C.

When propylene carbonate is used in polyurea grease, the fluorinated elastomers have less or no tendency to harden. According to the recommendations of the elastomer manufacturers, greases that cause a hardness change of significantly more than 10 points with regard to the penetration hardness (Shore A) according to DIN EN ISO 7619-1 are considered incompatible with the affected elastomer.

The results are summarized in Table 4. <i>Table 4</i> example 1 Example 2 Example 3 B1-A B1-B B1-C B2-A B2-B B2-C B3-A B3-B B3-C Thickener composition MDI/p-toluidine, cyclohexylamine MDI / Octylamine MDI / Octylamine, Cyclohexylamine // Ca-12-HSA Propylene carbonate [wt.%] 0 0.5 1 0 0.5 1 0 0.3 1 Temperature [°C] 180 180 160 Δ Shore A +15 +11 +2 +13 +7 +3 +8 +4 +1 Manual bending test of the fluorinated elastomer test specimen hardened somewhat flexible soft, flexible brittle breaks when bent a bit flexible flexible, brittle breaks when bent still flexible flexible

By adding 0.5% propylene carbonate to grease B2-B, the increase in hardness of the FKM elastomer could be halved. By adding 1% propylene carbonate (B2-C), the increase could be reduced to a harmless 3 points in terms of penetration hardness (Shore A) according to DIN EN ISO 7619-1.

Against the background of a maximum permissible change in hardness of 10 points (penetration hardness (Shore A) according to DIN EN ISO 7619-1), the comparison grease B3-A showed a borderline result (+8). By adding just 0.3% propylene carbonate (B3-B), the change in hardness could be reduced to a harmless range. By adding 1% propylene carbonate (B3-C), the elastomer remained almost unchanged in terms of its change in hardness.

Examples 4A and 4B

In addition to the improved compatibility of the polyurea grease composition with fluorinated elastomers, the usage properties in terms of service life and post-curing behavior can be improved by adding carbonates.

875.0 grams of Group I oil (paraffinic; 105-110cSt at 40°C) and 875.0g Group II oil (hard hydrogenated, paraffinic; 105-110cSt at 40°C) were placed in a heatable stirrer. To this oil mixture was added 31.5 grams of 4,4-methylene-bis-diphenyl diisocyanate (MDI). The reactor contents were heated to 55°C while stirring. A mixture of 12.5 grams of cyclohexylamine and 16.0 grams of N-octylamine was slowly metered in at 55 ° C. The exothermic reaction of isocyanate with the amine mixture caused the temperature to rise to 72°C. This temperature was held for 30 minutes to complete the formation of the thickener. With constant stirring, the reaction mixture was heated to a final temperature of 160 ° C within 3 hours. The reactor contents were then cooled to 135°C, followed by the addition of 180.0 grams of calcium 12-hydroxystearate. The mixture was stirred for 30 minutes at a constant temperature. The reaction was cooled to 60°C with continued stirring, followed by the addition of 10.0 grams of an amine antioxidant (Irganox L57). The base fat batch was then divided into parts A and B. Part B was transferred to a planetary mixer, 0.5% propylene carbonate was added at 25 ° C and mixed for 15 minutes.

Both batches A and B were finally homogenized using a colloid mill: Example 4A: without propylene carbonate / Example 4B: with 0.5% by weight of propylene carbonate

Example 4C

875.0 grams of Group I oil (paraffinic; 105-110cSt at 40°C) and 875.0g Group II oil (hard hydrogenated, paraffinic; 105-110cSt at 40°C) were placed in a heatable stirrer. To this oil mixture was added 31.5 grams of 4,4-methylene-bis-diphenyl diisocyanate (MDI). The reactor contents were heated to 55°C while stirring. A mixture of 12.5 grams of cyclohexylamine and 16.0 grams of N-octylamine was slowly metered in at 55 ° C. The exothermic reaction of isocyanate with the amine mixture causes the temperature to rise to 72°C. This temperature was held for 30 minutes to complete the formation of the thickener. With constant stirring, the reaction mixture was heated to a final temperature of 160 ° C within 3 hours.

The reactor contents were then cooled to 135°C, followed by the addition of 180.0 grams of calcium 12-hydroxystearate. The mixture was stirred for 30 minutes at a constant temperature. While stirring, 20.0 grams (1.0%) of propylene carbonate are added at 135 ° C. The mixture was then cooled to 80 ° C and 10.0 grams of an amine antioxidant (Irganox L57) were added. The batch was subsequently ground using a colloid mill. The characteristic values obtained are summarized in Table 5 below. Table 5 Designation Example 4 A Example 4 B Example 4 C Propylene carbonate [wt.%] 0 0.5 1.0 Temperature when adding the propylene carbonate 25°C 25°C 135°C RP-SF / DIN ISO 2137 296 306 293 RP-24h at 25°C / DIN ISO 2137 283 287 269 RP-24h at 100°C / DIN ISO 2137 215 221 225 ΔRP-24h (25°C vs. 100°C) -68 -66 -44 WP60 at 25°C / DIN ISO 2137 301 311 302 WP60000 / DIN ISO 2137 327 329 328 Δ60-60000 26 18 26 WP60-24h at 100°C / DIN ISO 2137 283 302 305 ΔWP 60 (25°C vs. 100°C) -18 -9 +3 Dropping point [°C] / DIN ISO 2176 207.9 207.3 200.7 Oil separation at 40°C, 18h 1.6% 1.6% 1.7% DIN 51817 FE9 according to DIN 51821 Installation type B, 140°C F10 9 h 45.8 hours 63.2 hours F50 44 hours 117.5 hours 92.8 hours

By adding organic carbonates, the consistency of the Walk Penetration WP60 is slightly softened. The dropping point of the fats is slightly reduced by adding propylene carbonate, whereas the oil separation remains at the same level.

A significant difference can be observed in the post-hardening behavior at elevated temperature (100°C) compared to 25°C: the rest penetration of fat samples that were stored for 24 hours (RP-24h) at 100°C decreases compared to those that Stored at 25°C for 24 hours, the fats harden significantly (compare ΔRP-24h). By adding 1% propylene carbonate, this post-curing effect could be reduced by around 30%.

An analogous picture can be observed during post-curing under temperature (100°C) with the full penetration WP60. By adding 1% propylene carbonate, the post-hardening of a fat sample stored for 24 hours at 100°C and then cooled to 25°C can be completely avoided compared to a fat sample stored at 25°C for full penetration WP60 (compare the WP60-24h values ), whereas greases without propylene carbonate showed significant post-hardening.

The FE9 test of the fats reveals another advantage of organic carbonates. With the example greases 4B and 4C, the downtimes F10 and F50 could be improved by over 50% by adding propylene carbonate.

Claims (15)

1. A polyurea grease composition comprising:

   a) at least one base oil;

   b) at least one polyurea thickener; and

   c) at least one organic carbonate, wherein the organic carbonate comprises 4 to 8 carbon atoms,

   wherein the composition comprises:

   a) 55 to 95% by weight of the base oil;

   b) 1 to 20% by weight of the polyurea thickener; and

   c) 0.1 to 10% by weight of the organic carbonate.
2. The polyurea grease composition according to claim 1, characterized in that the composition comprises:

   a) 70 to 90% by weight of the base oil;

   b) 1.5 to 15% by weight of the polyurea thickener; and

   c) 0.2 to 5% by weight, in particular preferably 0.5 to 2% by weight, of the organic carbonate.
3. The polyurea grease composition according to claim 1 or 2, characterized in that the composition furthermore comprises:

   d) 0.5 to 40% by weight, in particular 2 to 10% by weight, additives;

   e) 0 to 20% by weight, in particular 0 to 5% by weight, inorganic thickeners; and

   f) 0 to 20% by weight, in particular 0.1 to 15% by weight, solid lubricants.
4. The polyurea grease composition according to at least any one of the preceding claims, characterized in that the composition furthermore comprises:
   g) 0 to 20% by weight, in particular 1 to 15%, of further organic thickeners, in particular soap or complex soap thickeners on the basis of calcium soaps, lithium soaps, or aluminum soaps, in particular lithium soaps.
5. The polyurea grease composition according to at least any one of the preceding claims, wherein the composition contains no bentonites, no aluminosilicates, no aluminum oxides, no silicic acids, and no amorphous silicon dioxide, and in particular no inorganic thickeners.
6. The polyurea grease composition according to at least any one of the preceding claims, wherein the organic carbonate is a cyclic carbonate, in particular propylene carbonate.
7. The polyurea grease composition according to at least any one of the preceding claims, characterized in that the composition comprises a cone penetration value for the worked penetration of 220 to 430 mm/10 at 25°C, preferably 265 to 385 mm/10 at 25°C, determined according to ISO 2137.
8. The polyurea grease composition according to at least any one of the preceding claims, wherein the base oil comprises a kinematic viscosity of 20 to 2500 mm²/s, preferably of 40 to 500 mm²/s, in each case at 40°C.
9. A lubrication point comprising the polyurea grease composition according to at least any one of the preceding claims, and a seal comprising a sealing material, wherein the sealing material consists of an elastic fluoropolymer.
10. A component comprising

    a) at least one lubrication point,

    b) a seal, comprising a sealing material, wherein the sealing material consists of an elastic fluoropolymer, and

    c) the polyurea grease composition according to at least any one of claims 1 to 7 in contact with the lubrication point and the seal.
11. The lubrication point according to claim 9 or the component according to claim 10, wherein the elastic fluoropolymer is a fluororubber elastomer.
12. The lubrication point according to claim 9 or the component according to claim 10, wherein the seal is an O-ring or profile ring, a radial shaft seal, a sliding ring seal, a gland seal, a flat seal, a lip seal, a wiper, or a sealing cord.
13. The component according to claim 10, wherein the component is a shaft, a gearbox, a piston, a joint, a ball bearing, or sliding bearing.
14. Use of the polyurea grease composition according to any one of claims 1 to 7 for a lubrication point or a component according to claim 9 to 13.
15. A method for producing the polyurea grease composition according to at least any one of claims 1 to 8, wherein the method comprises the production of a polyurea in at least one portion of the base oil in the heat, and the addition of the organic carbonate takes place after production of the polyurea in the base oil and in during cool-down to a temperature of between 100° to 135°C.