Manufacturing of polyurea-thickened grease with improved lubrication properties and long-term stability.

Abstract

The present invention relates to a method for producing an intermediate product of polyurea thickened grease, and the method comprises or includes the following steps. a) To provide at least one first thickener precursor; b) To provide at least one second thickener precursor; c) A quantitative supply of the thickener precursor provided in steps a) and b) into the mixing chamber, and optionally adding at least one additional additive; d) Mix at least two thickener precursors and optionally at least one further additive in a mixing chamber and react the two thickener precursors; e) Obtaining a grease intermediate product thickened with at least one polyurea, wherein at least one thickening agent precursor provided in step a) and step b) and / or at least one additive in step c) has a temperature in the range of 0°C to less than 40°C, preferably in the range of 10°C to less than 40°C, in order to ensure cooling during the reaction in step d).

Description

[Technical Field]

[0001] This invention relates to the field of grease production, particularly to the production of grease thickened with polyurea. The invention proposes a method for producing a grease precursor and a method for producing the final grease product. Furthermore, the use of an apparatus for producing grease according to this invention, and a grease based on this invention, are also presented. [Background technology]

[0002] In friction (tribology) systems used in many technical applications, it is important to use lubricants to reduce friction and wear at the contact surfaces between moving parts. In such cases, lubricants of different consistency can be used depending on the application. Lubricating oils have a fluid, liquid consistency, while greases have a semi-solid to solid, often gel-like consistency.

[0003] A characteristic property of grease is that the fluid oil component is absorbed and retained by the thickening agent component. The gel-like consistency of grease, along with its ductility and easy plastic deformation properties, combined with its adhesiveness, ensure that the grease covers the lubrication point and exerts a lubricating effect on surfaces subjected to frictional (tribological) stress. In addition to additives, grease substantially contains a thickening agent dispersed in the base oil.

[0004] The most important rheological properties of grease include its consistency or yield point, resistance to post-hardening under thermal and mechanical loads, resistance to excessive oil separation, and stable viscosity-temperature and viscosity-shear behavior. Extensive practical experience is required to create greases with high practical value that reflect the requirements of specific applications.

[0005] In the field of grease, in order to produce grease that is stable over time and compatible with materials, it is important that the thickener is distributed with small and uniform particle sizes, and at the same time, that the thickener molecules are generated with high selectivity, substantially reducing chemical side reactions. Grease produced in this way results in extended bearing life, improved bearing stability, extremely good noise characteristics, improved compatibility with sealing materials, reduced health burden on users, and improved environmental tolerance.

[0006] The production of polyurea-thickened greases is an important research topic. Therefore, GB776548A discloses a process for producing metal soap-thickened greases, to which the method principle for polyurea greases can be applied, and the reaction mixture undergoes strong shear in the reaction region. Alternatively, the reaction mixture, which is fully or partially reacted, can be circulated between the sheared region and the non-sheared region while new reactants are added.

[0007] EP1062307B1 discloses a discontinuous manufacturing method for both soap-thickened grease and polyurea grease. In this method, the polyurea grease is passed through a homogenizer and subjected to shearing during production. This is intended to obtain good noise characteristics based on testing using the SKF BeQuiet method.

[0008] EP1322732B1 discloses a discontinuous method for producing low-noise grease in which 95% of the thickener particle size is specified to be less than 100 μm. In this method, first, a thickener is produced by reacting a diisocyanate with an amine. Then, the mixture of the thickener and base oil is sheared for a certain period of time at a temperature of 35°C to 55°C until the desired particle size is reached, then heated to 150°C to 175°C, and then cooled to 25°C to 105°C. After that, the grease is crushed to obtain a homogeneous lubricating grease.

[0009] US2010 / 0029526A1 discloses the production of low-noise polyurea grease by sequentially adding two or more amines, which are pre-dissolved in oil, to an isocyanate, which is pre-dissolved in oil, in a reactor.

[0010] EP1322732B1 discloses the continuous production of polyurea grease by "reactive injection molding." In this process, the reactive components, amines and isocyanates, are diluted or dissolved in solvents, and then simultaneously injected into a high-pressure injection unit under high pressure to produce a polyurea thickener.

[0011] US8703671B2 discloses the continuous production of polyurea grease using a reaction-type (twin-screw) screw extruder. A key feature of this process is that reactive components such as isocyanates and amines can be introduced from various positions in the extruder while the base oil is metered and added from another position. The process also describes supplying reactive components pre-dissolved in the oil. Furthermore, the temperatures of each reaction zone are described ("mixing cooling zone").

[0012] EP3031888B1 contains an amine pre-dissolved in oil and an isocyanate dissolved in oil, 10 2 The production of polyurea grease is described by simultaneously introducing it into a shear cell having a specified shear rate exceeding / s. In this case, the shear rate is defined as the quotient obtained by dividing the relative velocity between the rotating internal member and the inner wall of the shear cell by the minimum distance between the two members. The shearing of the reactants, which are pre-dissolved in the oil, is carried out within 15 minutes after they are mixed. The reaction between the isocyanate and the amine is carried out at 60-120°C.

[0013] EP3255130A1 describes the production of low-noise greases based on at least one aromatic amine and other amines, based on the process of EP3031888, the method being applied such that the average thickener particle size of the correspondingly produced grease is less than 1.6 μm by arithmetic mean. The average particle size is measured using static light scattering.

[0014] EP3150688B1 describes the production of greases based on isocyanates and mixtures of alicyclic and aliphatic amines according to the method of EP3031888. The noise requirements for the correspondingly produced grease are "Peak High 32-64s ≤ 1.5 and Level High 32-64s ≤ 10", which are specified by the FAG method (also known as ISO 21250-3 "method MQ").

[0015] JP2017115109A describes a special design for a rotor / stator shear cell disclosed in EP3031888, in which the shear rate of amines and isocyanates pre-dissolved in oil can be adjusted independently of the speed of the rotating member by changing the shear gap width.

[0016] Conventional techniques have not demonstrated that the reaction temperature is important for the quality of the grease obtained. Known methods for producing polyurea greases are either continuous manufacturing processes that cannot be used in the agitated reactors widely used in the lubricants industry for batch grease production, or discontinuous methods for which solutions have not been found to address the problems of shear heat generation at high shear rates and the exothermic reactions of amines, alcohols, and isocyanates. As a result, undesirable chemical by-products or decomposition products are formed during the synthesis of thickeners, leading to undesirable grease properties.

[0017] Therefore, the free amines reformed during the thermal decomposition of the urea group can increase plastic intolerability and skin intolerance. Free amines can also increase odor problems. Furthermore, free amines pose toxicological health risks to users. In addition, high reaction temperatures can cause volatile amines or alcohols (e.g., cyclohexylamine / cyclohexanol) that have not reacted sufficiently with the isocyanate to evaporate, potentially resulting in a polyurea thickener and its properties (e.g., degree of thickening) not being obtained. Another effect is that isocyanates that have not yet reacted sufficiently with amines and alcohols may decompose due to excessively high temperatures and any residual moisture in the oil, producing free aromatic amines via the intermediate formation of carbamic acid and subsequent decarboxylation. Such aromatic amines, as mentioned earlier, have many disadvantages. Furthermore, free isocyanates also pose toxicological health risks to users. In addition, oligomerization of isocyanates (uretdione formation, isocyanurate formation), or the formation of biuret oligomers or allophanate oligomers may occur, which inhibit thickening performance and increase the thermal and oxidative degradation of the grease over time. It has been empirically confirmed that free amines, alcohols, or isocyanates frequently cause unintended re-solidification of polyurea greases during storage or use. [Overview of the project]

[0018] Therefore, the object of the present invention was to provide a method for producing a polyurea-thickened grease that is of high quality and has excellent long-term stability, and to suppress the generation of undesirable by-products in the manufacturing process of the thickener.

[0019] This problem is solved by providing a method for producing a grease intermediate product thickened with at least one polyurea, in a first embodiment of the present invention. This method consists of, or includes, the following steps: a) To provide (prepare) at least one first thickener precursor; b) To provide (prepare) at least one second thickener precursor; c) Place the thickener precursors provided in steps a) and b) into a mixing chamber and add, optionally, at least one further additive; d) In a mixing chamber, mix at least two thickener precursors and at least one additional additive of any choice, and react the two thickener precursors; e) Obtain a grease intermediate product thickened with at least one polyurea. In this method, in order to ensure cooling during the reaction in step d), at least one of the thickener precursors provided in steps a) and b) and / or at least one of the additives in step c) are in a temperature range of 0°C or higher and less than 40°C, preferably 10°C or higher and less than 40°C.

[0020] This invention relates to the production of greases based on various base oils and thickeners based on organically substituted urea and / or urethane molecules having aliphatic, alicyclic, and aromatic hydrocarbon groups. The presence of multiple urea groups or urethane groups simultaneously results in the corresponding lubricating grease being called polyurea grease or polyurethane grease, or in its hybrid form, polyurea / polyurethane grease. Generally, "polyurea grease" or "grease thickened with polyurea" are used to describe this group.

[0021] The "grease intermediate product" within the scope of the present invention is a product that functions as the basis of lubricating grease but is further processed so that it can still be used in a grease lubricated tribological system. The grease intermediate product is usually a thickener, which may already be present together with at least one base oil and / or at least one additive, and is converted into the final product by further processing steps such as heating or grinding. Furthermore, the grease intermediate product or thickener is preferably a polyurea thickener, and is then converted into the final polyurea thickened grease product by an additional step involving the addition of further base oil and further additives.

[0022] The thickener precursors provided in steps a) and b) are reactants (starting materials, educts) that react in the mixing and reaction step d) to form a thickener or a grease intermediate product. These are preferably the amines and / or alcohols and isocyanates described later.

[0023] The additives added in step c) are optional components in the production of grease and can be added to improve or impart specific properties to the grease.

[0024] In one embodiment, the grease intermediate product is a polyurea thickener consisting of the reaction product of an amine and an isocyanate. According to one embodiment, the polyurea thickener can be obtained as the reaction product of a C6 - C20 hydrocarbyl monoamine and a diisocyanate. Alternatively, the reaction product of a monoisocyanate (which may optionally also include a diisocyanate) and a diamine may also exist. The polyurea thickener is more preferably not polymeric but is, for example, a dimer, trimer, tetramer or other oligomer. Therefore, isocyanates of the R - NCO type (monoisocyanates) can also be used in the same manner as polyisocyanates, where R preferably represents a hydrocarbon group (radical) having 5 to 20 carbon atoms.

[0025] Diureas can preferably be obtained from diisocyanates and monoamines, or tetraureas can be obtained from diisocyanates, monoamines and diamines (each as defined above). Particularly preferred are diureas based on 4,4'-diphenylmethane diisocyanate (MDI) or toluene-2,4-diisocyanate (TDI) and an aliphatic, aromatic and / or cyclic primary monoamine, or tetraureas based on MDI or TDI and an aliphatic, aromatic and / or cyclic monoamine and diamine.

[0026] Step d) is a step of mixing the two thickener precursors provided in steps a) and b) with each other, which is a step of producing a grease intermediate product, preferably a polyurea thickener. For this purpose, preferably provided (prepared) amine and / or provided (prepared) alcohol react exothermally with isocyanate to produce a urea or urethane.

[0027] The concentrations of undesirable byproducts in the reaction of desired urea / urethane molecules and polyurea thickeners are primarily determined by their reaction rates and equilibrium points. The equilibrium point is heavily skewed towards the product side due to the exothermic nature of the reaction. The reaction rate depends on both the reaction rate and mass transfer. The reaction rate increases with increasing temperature. Mass transfer is highly dependent on the concentration and flow behavior (e.g., mixing / viscosity) of the reactants (educts), and is therefore indirectly related to temperature. In high-rate reactions, mass transfer is typically the rate-limiting factor, whereas in rate-limited reactions, mass transfer is often less significant. The rate of urea / urethane formation from the reaction of amines / alcohols with isocyanates is very high; therefore, it is rather limited by mass transfer. For this reason, shearing is often performed during the reaction in the prior art. Compared to urea formation reactions, the rates of undesirable side reactions are slower and primarily kinetically limited. As the reaction temperature increases, the rate of side reactions increases, while the urea formation / urethane formation reaction is not significantly affected due to limitations in mass transfer. This means that increasing the reaction temperature leads to an increase in the formation of by-products.

[0028] Surprisingly, based on the present invention, it has been found that the formation of by-products can be limited by adding at least one thickening agent precursor and / or at least one additive at a temperature of 0°C or higher and below 40°C, preferably 10°C or higher and below 40°C, and particularly preferably 10°C or higher and below 35°C. This is particularly surprising, because in the prior art, particularly in stirred reactors, the reactor jacket was cooled to control the temperature. However, this cooling by the reactor jacket is not sufficient to regulate the temperature inside the reactor to the extent that the formation of by-products is minimized. In particular, insufficient cooling by the reactor jacket is observed when the thickening effect of the grease intermediate product being produced begins to occur and heat transfer by convection substantially decreases. In contrast to the prior art described above, which provides little information on the effect of temperature or cooling, the present invention specifies a particularly advantageous method by the presented temperature range.

[0029] In step c), it is preferable to add the cooled additive at a temperature of 0 to 40°C, preferably 10°C or higher and below 40°C, and particularly preferably 10°C or higher and below 35°C. The additive is especially preferable if it is a cooled base oil.

[0030] At least one additive is preferably added in step d) at a temperature below 0°C for cooling. If it is preferable to add the additive at a temperature below 0°C, condensation can be avoided by means known to those skilled in the art, for example, by using a dry atmosphere or an inert gas.

[0031] The present invention preferably relates to a method according to the present invention, in which case the first thickener precursor provided in step a) is selected from the group consisting of primary amines, preferably monoaminohydrocarbyl-, di-, or polyaminohydrocarbylene compounds having 6 to 20 carbon atoms, or alcohols having a hydrocarbyl group or hydrocarbylene group having 6 to 20 carbon atoms, or mixtures thereof, and the first thickener precursor exists as a pure substance or as a mixture with at least one base oil.

[0032] Suitable amines as the first thickener precursor are described, for example, on page 1, line 51 to the end of page 16 of EP0508115A1. Suitable alcohols may also contain a hydrocarbyl group or a hydrocarbylene group, each preferably having 6 to 20 carbon atoms, and particularly preferably 6 to 18 carbon atoms. The hydrocarbylene group preferably contains an aliphatic group, particularly an alkyl group or an alkylene group. It may also contain an aromatic group. The alcohol may be a monoalcohol, diol, or polyol. Monoalcohols and D-alcohols are preferred, and monoalcohols having a chain length of 6 to 18 carbon atoms are particularly preferred.

[0033] Base oils can be classified as mineral oils or synthetic oils. For example, naphthenic mineral oils and paraffinic mineral oils are considered mineral oils based on their classification in API Group I. Chemically modified mineral oils with low aromatic and sulfur content, a low proportion of saturated compounds, and improved viscosity / temperature behavior compared to API Group I oils, and classified as API Group II and III, are also preferred.

[0034] Synthetic oils are understood to include, in particular, polyethers, esters, polyalphaolefins, polyglycols, alkylated aromatics and mixtures thereof, as well as silicone oils. Polyether compounds may contain free hydroxyl groups, but may be fully etherified or have terminal groups esterified, and / or may be produced from starting compounds having one or more hydroxyl groups and / or carboxyl groups (-COOH). Polyphenyl ethers (optionally alkylated) can also be used as single components or more preferably as hybrid components. Esters of aromatic di, tri, or tetracarboxylic acids with C2-C22 alcohols or mixtures of several such alcohols, esters of adipic acid, sebacic acid, trimethylolpropane, neopentyl glycol, pentaerythritol, or dipentaerythritol with aliphatic branched or unbranched saturated or unsaturated C2-C22 carboxylic acids, C18 dimer acid esters with C2-C22 alcohols, and complex esters are suitable for use as single components or mixtures.

[0035] The present invention also relates to a method in which, preferably, the at least second thickener precursor provided in step b) is an isocyanate, preferably having 5 to 20 carbon atoms, and particularly preferably having 6 to 15 carbon atoms, selected from the group consisting of monoisocyanates and / or polyisocyanates, or mixtures thereof, and the second thickener precursor exists as a pure substance or as a mixture with at least one base oil.

[0036] Monoisocyanates and / or polyisocyanates, preferably polyisocyanates which are hydrocarbons having two isocyanate groups, are suitable for use as isocyanate components (second thickener precursors). The isocyanates contain 5 to 20 carbon atoms, preferably 6 to 15 carbon atoms, and preferably contain aromatic groups.

[0037] Within the scope of the present invention, preferred is a method in which at least one additive is selected from the group consisting of base oils, volatile hydrocarbons, cooling gases or liquefied gases, amines, alcohols, isocyanates, antioxidants, wear protection agents, corrosion inhibitors, detergents, dyes, lubricity enhancers, bonding enhancers, viscosity additives, friction reducers, high-pressure additives or metal deactivators, simple soaps and / or complex soaps, preferably in the form of lithium, sodium, magnesium, calcium, aluminum or titanium soaps, water, or mixtures thereof.

[0038] These soaps may be added as additives or formed in situ during the production of the grease. The polyurea-thickened grease intermediate product or polyurea thickener and the soap or complex soap thickener are preferably used together and further processed to obtain the final product. In this case, lithium soap, aluminum soap or aluminum complex soap, calcium sulfonate soap or calcium sulfonate complex soap, calcium soap or calcium complex soap are particularly preferred, with a mixing ratio of 10:1 to 1:10, particularly 5:1 to 1:5 (in each case, the ratio of mass to mass). The soap or complex soap thickener and the polyurea thickener are then preferably used together in an amount of 5 to 25% by weight relative to the polyurea-thickened grease (final product). Here, the polyurea-thickened grease intermediate product or polyurea thickener is used in an amount of at least 1% by weight, preferably at least 1.5% by weight, relative to the polyurea-thickened grease (final product).

[0039] Polymer powders, preferably polyamide, polyimide, or PTFE, melamine cyanurate, graphite, metal oxides, boron nitride, silicates such as magnesium silicate hydrate (talc), sodium tetraborate, potassium tetraborate, molybdenum disulfide, tungsten disulfide, or metal sulfides such as hybrid sulfides based on tungsten, molybdenum, bismuth, tin, and zinc, and inorganic salts of alkali metals and alkaline earth metals, such as calcium carbonate, sodium phosphate, and calcium phosphate, can preferably be used as additives. Other carbon-based solid lubricants such as carbon black or nanotubes can also preferably be added as additives. Furthermore, lignin sulfonates of alkali metals or alkaline earth metals, particularly lignin derivatives of calcium lignin sulfonate, may also be used in amounts ranging from 2 to 15% by weight, for example, based on WO2011095155A1 or US8507421B2, to obtain specific properties.

[0040] Organic carbonates can also be added as additives to improve the performance characteristics of the polyurea-thickened grease according to the present invention, and to improve the compatibility between the polyurea-thickened grease and the fluorinated elastomer upon use. The organic carbonate preferably has 4 to 8 carbon atoms. The radicals or components of the organic carbonate (excluding the carbonate group itself) are hydrocarbons, meaning that the organic carbonate is not substituted with heteroatoms. Organic cyclic carbonates, particularly those with 4 to 8 carbon atoms, especially 4 or 5 carbon atoms, are preferred. The cyclic carbonate may be added during the production of the polyurea-thickened grease according to the present invention, but more preferably, it may be added as an additive during the cooling stage after the production of the polyurea-thickened grease intermediate product.

[0041] Further additives that can be preferably added within the scope of the present invention are preferably selected from the following: Primary antioxidants: e.g., amine compounds (e.g., alkylamines or 1-phenylaminonaphthalene), aromatic amines (e.g., phenylnaphthylamine or diphenylamine), or polymeric hydroxyquinolines (e.g., TMQ), phenolic compounds (e.g., 2,6-di-tert-butyl-4-methylphenol), zinc dithiocarbamate, or zinc dithiophosphate; Secondary antioxidants: for example, phosphites (e.g., tris(2,4-di-tert-butylphenyl) phosphite or bis(2,4-di-tert-butylphenyl)-pentaerythritol diphosphite) or thioethers (e.g., cresol thioether); • High-pressure additives and / or wear protection additives: e.g., sulfur or organic sulfur compounds (e.g., polysulfides or sulfurized olefins), overbasized calcium sulfonates, thiophosphates, phosphorus compounds (e.g., alkyl phosphates neutralized with amines); Inorganic or organoboron compounds: zinc dialkyldithiophosphate, organobismuth compounds, thiophosphonates (e.g., triphenylthiophosphate), phosphonates (phosphites, e.g., dioctylphosphonate), alkylsulfonates, (methylene-bis(dibutyldithiocarbamate, dithiocarbamate); • Oiliness-enhancing substances: C2-C6 polyols, fatty acids, fatty acid esters, or animal or vegetable oils; • Corrosion inhibitors: e.g., sulfates (e.g., petroleum sulfonates, dinonylnaphthalene sulfonates, or sorbitan esters), neutralized or overbasified calcium sulfonates, magnesium sulfonates, sodium sulfonates, calcium- and sodium naphthalene sulfonates, sulfonic acid esters, disodium sebacate, calcium salicylate, aminophosphites, succinates; • Metal deactivators: e.g., benzotriazole (e.g., methylbenzotriazole dialkylamine), sterically hindered phenol, sodium nitrite; Viscosity enhancers: e.g., polymethacrylate, polyisobutylene, oligodecene-1-ene, polystyrene; • Friction reducers (those with partial wear resistance): For example, organic molybdenum complexes (OMC), molybdenum dialkyldithiophosphates, molybdenum dialkyldithiocarbamates (especially molybdenum di-n-butyldithiocarbamate and molybdenum dialkyldithiocarbamate (Mo 2m S n (Dialkylcarbamate)2, where m=0-3 and n=1-4), zinc dithiocarbamate or zinc dithiophosphate; Alternatively, a trinuclear molybdenum compound represented by the following formula: Mo3S k L n Q Z (wherein L is a ligand having an organic group having a carbon atom, for the purpose of making the compound soluble or dispersible in oil (disclosed, for example, in US6172013B1), n ​​is 1 to 4, k is 4 to 7, Q is selected from the group of neutral electron-donating compounds consisting of amines, alcohols, phosphines and ethers, and z is in the range of 0 to 5, including non-stoichiometric values ​​(see DE102007048091)) Organic acids (e.g., isostearic acid), functional polymers (e.g., oleylamide), organic polyethers and amide compounds (e.g., alkyl polyethylene glycol tetradecylene ether), PIBSI (polyisobutylene succinic anhydride), partial glycerides, hydrogen dialkylphosphonates, alkyl succinates.

[0042] More preferably, the method according to the present invention is to achieve the cooling of the reaction in step d) by adding an evaporable component as an additive in step c).

[0043] When using evaporative components, cooling can be achieved by utilizing the enthalpy of evaporation of these components. The boiling points of these components are preferably lower than the reaction temperatures reached by the two thickening agent precursors.

[0044] More preferably within the scope of the present invention is a method according to the present invention in which the cooling of the reaction in step d) is also achieved by adding a sublimable component as an additive in step c).

[0045] The method according to the present invention preferably involves a base oil with a base oil content of 12 to 2500 mm at 40°C. 2 It has a kinematic viscosity of / s, preferably 30-500 mm². 2 This relates to a method having a kinematic viscosity of / s.

[0046] More preferably within the scope of the present invention is that the mixing in step d) is carried out in a mixing chamber under shear.

[0047] Reactants (educts) that are poorly soluble or insoluble in the base oil can preferably be converted into the grease intermediate product in the mixing chamber under shear. Such reactants that are poorly soluble or insoluble in the base oil at temperatures below 20 °C can also preferably be converted under shear as described herein.

[0048] During the formation reaction of the grease intermediate product thickened with polyurea (thickener), for example, from amines (or alcohols) and isocyanates, depending on the selected starting materials and their stoichiometry, diureas or tetraureas can be formed. As a result of heating, these molecules can aggregate with each other to form a three-dimensional thickener structure. This can also be referred to as thickener particles in this context. Kinetic elements including temperature control and mechanical shear in the mixing chamber or shear chamber can also affect the three-dimensional formation of the thickener and its associated properties.

[0049] Shearing is preferably at least 10 2 / s shear rate, preferably at most 10 7 / s shear rate, particularly preferably in the range of 10 [[ID=*13]] 2 / s or more and 10 6 / s or less.

[0050] The shear rate is preferably calculated from the ratio of the speed difference between adjacent rotating and non-rotating members (e.g., rotor and stator) and the distance between them.

[0051] Even more preferred within the scope of the present invention is to perform shearing using at least one of the following: - A rotor-rotor shearing mechanism, i.e., a homogenizer having, for example, preferably two rotatable shearing elements arranged in a housing or container and which can be driven in opposite or the same direction, such as those described in European Patent No. EP1125625 or EP1825907; - A rotor-stator shearing mechanism, i.e., a homogenizing device that is movable relative to a stationary stator, for example, comprising, preferably, a rotatable shearing element located in a housing or container, such as those described in, for example, European Patent No. EP3031888B1 or EP3255130A1; - A rotor-stator-rotor shearing mechanism, i.e., a homogenizing device comprising, for example, preferably two rotatable shearing elements arranged in a housing or container, which can be driven in opposite or the same direction, and further having a fixed stator, such as those described in European Patent No. EP1125625 or EP1825907; - High-pressure injection chamber (high-pressure injection chamber); - Static mixer; - Extruders, especially screw extruders; - Pump unit / pump.

[0052] Shearing is particularly preferably performed in the rotor-rotor-stator system as described in EP1125625 or EP1825907. In a preferred embodiment, the method according to the present invention may be a method for producing polyurea-thickened grease comprising or including the steps described above, and further comprising the following steps: f) Heat the intermediate product obtained in step e) to a temperature above 100°C while stirring; g) Cool the heated intermediate product from step f) to a temperature of less than 100°C, preferably less than 80°C; h) Obtain grease thickened with polyurea.

[0053] The polyurea-thickened grease obtained in step h) can preferably be considered a finished product for use in tribological systems.

[0054] A further aspect of the present invention is a method for producing a grease intermediate product thickened with at least one polyurea, the method comprising or including the following steps: a) To provide at least one first thickener precursor; b) To provide at least one second thickener precursor; c) The thickener precursors provided in steps a) and b) are placed in a mixing chamber, and at least one additive is added, although this is optional; d) In a mixing chamber, mix at least two thickening agent precursors and at least one additional additive, and react the two thickening agent precursors; e) Obtain a grease intermediate product thickened with at least one polyurea. Here, as the first thickener precursor, a pure amine or a mixture of a pure amine and / or an alcohol is provided.

[0055] A pure amine thickener precursor is understood to mean that the thickener precursor contains none or substantially any of the base oils and / or additives described herein.

[0056] More preferably, and as described above, the first thickener precursor provided in step (a) is selected from the group consisting of a primary amine, preferably a primary amine having 6 to 20 carbon atoms, preferably a monoaminohydrocarbyl-, diamino or polyaminohydrocarbylene compound, or a mixture thereof. and / or, The first thickener precursor provided in step (a) is selected from the group consisting of at least one alcohol, preferably an alcohol having a hydrocarbyl or hydrocarbylene group having 6 to 20 carbon atoms, or a mixture thereof. And, The second thickening agent precursor provided in step (b) is selected from the group consisting of isocyanates, preferably monoisocyanates and / or polyisocyanates having 5 to 20 carbon atoms, particularly preferably 6 to 15 carbon atoms, or mixtures thereof of the above compounds. Here, the first and / or second thickener precursor exists as a pure substance or as a mixture with at least one base oil.

[0057] As described above, the method according to the present invention preferably further includes the following steps: f) Heat the intermediate product obtained in step (e) to a temperature exceeding 100°C while stirring; g) A step of cooling the intermediate product heated in step (f) to a temperature of less than 100°C, preferably less than 80°C; h) A step to obtain grease thickened with polyurea.

[0058] As described above, the polyurea-thickened grease obtained within the scope of the present invention is preferably a method product obtained by an in-situ reaction of an amine and an isocyanate as described herein in a base oil, and is then heated to obtain an intermediate product, and further cooled to obtain the final product, polyurea-thickened grease.

[0059] In the preceding description, the present invention has been described in relation to a method. In further embodiments, the present invention relates to an apparatus and / or use thereof. With respect to an apparatus and / or use thereof, the present invention solves the problems described in the introduction in that the apparatus includes a mixing chamber and a stirred reactor for mixing a thickener precursor. The mixing chamber preferably has at least two supply inlets for quantitatively introducing a shear element and a thickener precursor. The mixing chamber is preferably connected to the stirred reactor via a line. The stirred reactor is preferably equipped with a stirrer and preferably with a cooling jacket configured to cool the stirred reactor. In one embodiment, the stirred reactor is connected to the mixing chamber via a connector.

[0060] This apparatus and its use have similar advantages and preferred embodiments as the method according to the present invention, and vice versa. In this regard, please refer to the preceding description, which is incorporated herein by reference.

[0061] A further aspect of the present invention relates to the provision of polyurea-thickened grease, preferably a grease obtained or obtainable by a method according to any of the embodiments described above, comprising the following components: a) 55-95% by weight, preferably 70-90% by weight of base oil; b) 1 to 20% by weight, preferably 1.5 to 15% by weight of a polyurea thickener; And, although optional, at least one of the following additional ingredients: c) 0.5 to 40% by weight, preferably 2 to 10% by weight of additives; d) 0-20% by weight, preferably 0-5% by weight, of an inorganic thickener, preferably silicon dioxide; f) 0 to 20% by weight, preferably 0.1 to 15% by weight, of a solid lubricant; g) 0-20% by weight, particularly 1-15% by weight, of an additional organic thickener, preferably a soap or complex soap thickener based on calcium, lithium, or aluminum soap; h) 1-15% by weight of a lignin derivative. Here, polyurea-thickened grease is virtually biuret-free.

[0062] Biuret forms as an undesirable by-product (e.g., biuret oligomer) during the reaction of isocyanates partially converted with free isocyanates and / or amines, for example, as biuret oligomers. This is undesirable because it can lead to reduced thickening performance and increased thermal and oxidative degradation (aging) of the grease. Furthermore, biuret can dissociate during the process, generating free amino groups. As mentioned above, the free amines reformed by the thermally induced dissociation of the urea group can cause increased plastic and / or elastomer intolerability, as well as increased skin intolerance. In addition, free amines can also increase odor. Free amines also pose a risk of toxicological harm to users.

[0063] In the context of the present invention, the phrase "substantially free from" means that a particular substance is present in an amount below the detection limit or at a level of 2000 ppm or less, preferably 1000 ppm or less, and particularly preferably 500 ppm or less.

[0064] The polyurea-thickened grease according to the present invention has a cone penetration value of preferably 200-400 mm / 10, more preferably 265-385 mm / 10, as measured according to DIN ISO 2137.

[0065] Grease penetration should be understood as the depth of penetration measured under specified conditions using a standard cone (measured in units of 0.1 mm).

[0066] Preferably, as component (g), a soap thickener or a complex soap thickener is present in the polyurea-thickened grease. In this case, the soap thickener or complex soap thickener is added, for example, at an appropriate temperature during the cooling process after the manufacture of the base grease (e.g., 140-115°C, adding the soap thickener or complex soap thickener, especially calcium soap or calcium complex soap).

[0067] To produce the base grease, the temperature is preferably raised to over 100°C, and particularly preferably to over 130°C. Heating is performed after the thickener precursor has reacted to form a grease intermediate product. The conversion to the base grease is carried out in a heated reactor, which may be designed as an autoclave or a vacuum reactor.

[0068] Subsequently, cooling completes the formation of the thickener structure in the second step. Furthermore, additional components such as additives and / or base oils may be added, although this is optional, to achieve the desired consistency or desired property profile. The second step may be carried out in the same reactor used in the first step, but it is preferable to remove the base grease from the reactor and transfer it to a separate stirred tank for cooling and mixing of the other components.

[0069] The present invention will be described in more detail below, based on preferred embodiments and with reference to the accompanying drawings. [Brief explanation of the drawing]

[0070] [Figure 1] Exemplary embodiments of a system 2 relating to a method and use based on the present invention are shown.

[0071] System 2 includes a mixing chamber 16 and a stirred reactor 11 for mixing a thickener precursor. The mixing chamber 16 is equipped with a shear element 17 and a feed inlet 18 for quantitatively introducing the thickener precursor. Although four independent feed inlets A-D are shown in the figure for illustrative purposes, three inlets are specifically sufficient for the method described herein. The mixing chamber 16 is connected to the stirred reactor 11 via line 13. The stirred reactor 11 has a stirrer 12 and a cooling jacket 14. The stirred reactor 11 is connected to the mixing chamber 16 via a connector 15.

[0072] The mixing chamber 16 includes a shear element 17, which can be embodied as a rotary shear element 17 (as shown), or as a rotor-rotor shear mechanism, rotor-stator shear mechanism, rotor-stator-rotor shear mechanism, high-pressure injection chamber, static mixer, extruder, particularly screw extruder, or pump unit / pump.

[0073] Referring to Figure 1, the method according to the present invention can be described as follows: A first thickener precursor and a second thickener precursor are quantitatively introduced into the mixing chamber 16 via supply inlets 18, such as supply inlets A and B. The thickener precursors are mixed in the mixing chamber 16, thereby reacting the precursors and subjecting them to shearing by the shear element 17. Optionally, an additive may be supplied to the mixing chamber 16 via supply inlet C, for example. According to the present invention, at least one thickener precursor and / or additive is added at a temperature in the range of 0°C to less than 40°C. The mixture is transferred as a mixture to the agitated reactor 11 via line 13, where it is stirred by a stirrer 12. Furthermore, the fluid contained in the agitated reactor 11 may be cooled by a cooling jacket 14. The fluid may be transferred from the agitated reactor 11 to the mixing region 16 via a connection 15. To obtain polyurea-thickened grease from polyurea-thickened grease intermediate products, the intermediate products are heated to a temperature exceeding 100°C while being stirred in a stirring reactor 11, and then immediately cooled again to finally obtain polyurea-thickened grease.

Claims

1. A method for producing a polyurea-thickened grease intermediate product, comprising the following steps: a) To provide at least one first thickener precursor; b) To provide at least one second thickener precursor; c) Add the thickener precursors provided in steps a) and b) to the mixing chamber and optionally add at least one more additive; d) Mixing at least two thickener precursors and at least one additional additive in a mixing chamber, and reacting the two thickener precursors; e) Obtain a grease intermediate product thickened with at least one polyurea; Consists of, or includes these A method for producing a grease intermediate product, wherein, in order to ensure cooling during the reaction in step d), at least one of the thickener precursors provided in steps a) and b) and / or at least one of the additives in step c) are at a temperature in the range of 0°C or higher and less than 40°C, preferably 10°C or higher and less than 40°C.

2. The first thickening agent precursor provided in step a) is selected from the group consisting of primary amines, preferably monoaminohydrocarbyl-, di-, or polyaminohydrocarbylene compounds having 6 to 20 carbon atoms, or alcohols having a hydrocarbyl group or hydrocarbylene group having 6 to 20 carbon atoms, or mixtures thereof. The method according to claim 1, wherein the first thickener precursor exists as a pure substance or as a mixture with at least one base oil.

3. The at least second thickening agent precursor provided in step b) is selected from the group consisting of isocyanates, preferably monoisocyanates and / or polyisocyanates having 5 to 20 carbon atoms, particularly preferably 6 to 15 carbon atoms, or mixtures thereof. The method according to claim 1 or 2, wherein the second thickener precursor exists as a pure substance or as a mixture with at least one base oil.

4. The method according to any one of claims 1 to 3, wherein at least one additive is selected from the group consisting of a base oil, a volatile hydrocarbon, a coolant or liquefied gas, an amine, an alcohol, an isocyanate, an antioxidant, an anti-wear agent, a rust inhibitor, a cleaning agent, a dye, a lubricity enhancer, an adhesion enhancer, a viscosity additive, a friction reducer, a high pressure additive or a metal deactivator, a simple soap and / or a complex soap, preferably in the form of a lithium, sodium, magnesium, calcium, aluminum or titanium soap, water, or a mixture thereof.

5. The method according to any one of claims 1 to 4, wherein the cooling of the reaction in step d) is further accelerated by adding an evaporative or sublimable component as an additive in step c).

6. The base oil has a viscosity of 12 to 2500 mm at 40°C. ２ It has a kinematic viscosity of 1 / s, preferably 30 to 500 mm ２ The method according to any one of claims 1 to 5, having a kinematic viscosity of / s.

7. The method according to any one of claims 1 to 6, wherein the mixing in step d) is carried out under shear in a mixing chamber.

8. Shearing, shear rate 10 ２ This is performed at a rate of / s or higher, preferably up to a maximum of 10 ７ The process is carried out at a shear rate of / s, and is particularly preferably 10 ２ / s or more, 10 ６ The method according to claim 7, which is performed within a range of / s or less.

9. Shearing is performed by the following means: - Rotor - Rotor shearing mechanism, - Rotor-stator shearing mechanism, - Rotor - Stator - Rotor shear mechanism, - High-pressure injection chamber, - static mixer, - Extruders, especially screw extruders, - Pump unit / pump, The method according to claim 7 or 8, carried out by at least one of the means.

10. The steps described in any one of claims 1 to 9, and further the following steps: f) Heat the intermediate product obtained in step e) to a temperature above 100°C while stirring; g) Cool the intermediate product heated in step f) to below 100°C, preferably below 80°C; h) Obtain a grease thickened with polyurea. A method for producing polyurea-thickened grease, comprising or containing the following.

11. A method for producing a grease intermediate product thickened with at least one polyurea, comprising the following steps: a) To provide at least one first thickener precursor; b) To provide at least one second thickener precursor; c) Adding the thickener precursors provided in steps a) and b) to a mixing chamber and optionally adding at least one more additive; d) Mix at least two thickener precursors and at least one additional additive in a mixing chamber to react the two thickener precursors; e) Obtain a grease intermediate product thickened with at least one polyurea; Consists of, or includes these A method for producing a grease intermediate, wherein a single amine or a mixture of several single amines and / or alcohols is provided as a first thickener precursor.

12. As the first thickener precursor provided in step a), at least one amine is selected, preferably from the group consisting of primary amines, preferably monoaminohydrocarbyl-, di-, or polyaminohydrocarbylene compounds having 6 to 20 carbon atoms, or mixtures thereof. and / or, As the first thickener precursor provided in step a), at least one alcohol is selected, preferably from the group consisting of alcohols having a hydrocarbyl group or hydrocarbylene group having 6 to 20 carbon atoms, or mixtures thereof. Furthermore, The second thickening agent precursor provided in step b) is selected from the group consisting of isocyanates, preferably monoisocyanates having 5 to 20 carbon atoms, particularly preferably monoisocyanates having 6 to 15 carbon atoms and / or polyisocyanates or mixtures thereof. The method according to claim 11, wherein the first and / or second thickener precursor is present as a pure substance or as a mixture with at least one base oil.

13. The steps described in any one of claims 11 or 12, and further the following steps: f) Heat the intermediate product obtained in step e) to a temperature above 100°C while stirring; g) Cool the intermediate product heated in step f) to below 100°C, preferably below 80°C; h) Obtaining a grease thickened with polyurea; A method for producing polyurea-thickened grease, comprising or containing the following.

14. - Mixing chamber (16) for mixing thickener precursors, - Stirring reactor (11), A device equipped with, The mixing chamber (16) has at least two supply ports (18) for introducing shear elements (17) and thickener precursors, and is connected to a stirred reactor via piping (13), in particular the stirred reactor (11) is equipped with a stirrer (12) and a cooling jacket (14), and is optionally connected to the mixing chamber (16) via a connection (15), and the use of an apparatus for producing polyurea-thickened grease (10) or polyurea-thickened grease intermediate products according to the method of any one of claims 1 to 13.

15. Preferably, a polyurea-thickened grease obtained or obtainable by the method described in any one of claims 1 to 13, a) 55 to 95% by weight, preferably 70 to 90% by weight of base oil; b) 1 to 20% by weight, preferably 1.5 to 15% by weight of a polyurea thickener; And, although optional, at least the following additional components: c) 0.5 to 40% by weight, preferably 2 to 10% by weight of an additive; d) 0 to 20% by weight, preferably 0 to 5% by weight, of an inorganic thickener, preferably silicon dioxide; f) 0 to 20% by weight, preferably 0.1 to 15% by weight, of a solid lubricant; g) 0 to 20% by weight, particularly 1 to 15% by weight, of a further organic thickener, preferably a soap thickener derived from calcium, lithium, or aluminum soap, or a thickener for a complex soap; h) 1 to 15% by weight of a lignin derivative; Includes, A polyurea-thickened grease that is virtually biuret-free.

16. The polyurea-thickened grease according to claim 15, wherein the cone penetration value measured according to DIN ISO 2137 is 200 to 400 mm / 10, preferably in the range of 265 to 385 mm / 10.

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