EP4176027A1 - Polyurea lubricating greases containing carbonates, and their use - Google Patents

Abstract

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

Description

Polyurea lubricating greases containing carbonates and their use

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

Introduction and state of the art

For tribological systems, as 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.

A characteristic of a lubricating grease is that a liquid oil component is absorbed and retained by a thickener component. The pasty nature of a lubricating grease and its property of being spreadable and easily plastically deformable, together with the property of being able to adhere, ensures that the lubricating grease wets the lubrication point and that the lubricating effect unfolds on the tribologically stressed surfaces. In addition to additives, lubricating greases essentially comprise a thickening agent that is present in a base oil.

The most important theological properties of a lubricating grease include the consistency or its flow limit, the avoidance of post-hardening and excessive oil separation under thermal and mechanical stress, as well as a 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. Lubricating greases are often used in encapsulated or sealed environments in order to protect the lubrication point from water, to minimize grease losses and to prevent the ingress of particles such as sand or dust. Typical applications for lubricating greases are the lubrication of roller bearings, slide bearings, gears or constant velocity universal joint shafts.

Polyurea greases are often used for lubrication points that are exposed to high temperatures and / or aggressive environments. If sealing materials are used in such conditions of use, fluorinated elastomers that are more thermally and chemically particularly resilient are often used with regard to the selection of the sealing material. The combination of such a lubricating grease / sealing material pairing is often restricted, since the fluorinated elastomers tend to harden or even become brittle in the presence of the polyurea lubricating greases.

Various additives have been proposed to improve compatibility with fluorinated elastomers. Examples 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 activators / dispersants for inorganic thickeners, but not as additives for polyurea thickeners.

Object 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 or as little post-hardening as possible. Furthermore, polyurea lubricating greases are to be made available which have improved compatibility with fluorinated elastomers, such as those used as sealing materials, whereby the lubricating grease should not be adversely affected in its performance properties by any additives to increase the compatibility with fluorinated elastomers. Summary of the invention

The object is achieved by the subject matter of the independent claims. Be preferred embodiments are the subject matter of the subclaims or are described in the following.

The polyurea fat composition according to the invention comprises: 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; b) at least one polyurea thickener in an amount of 1 to 20% by weight, preferably 1.5 to 15% by weight; 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, in addition to c), additives can be used, 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 also 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 here as polyurea fat compositions.

In the following, the terms polyurea fat composition and polyurea fat (s) are used synonymously.

Detailed description of the invention

Customary 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 mineral oils and paraffinic mineral oils, according to classification 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 are, in particular, polyethers, esters, polyalphaolefins, polyglycols and alkyl aromatics and their mixtures, as well as silicone oils. The polyether compound can have free hydroxyl groups, but can also be completely etherified or end groups and / or be produced from a starter compound with one or more hydroxyl and / or carboxyl groups (-COOH). Polyphenyl ethers, optionally alkylated, are also possible as sole components or, better still, as mixed components. Esters of an aromatic di-, tri- or tetracarboxylic acid with one or 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 are suitable 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 can be obtained by reacting one or more amine components with one or more isocyanate components.

The starting materials for the production of the polyurea thickener are primary amines and isocyanates.

The amines are monoamino hydrocarbyl, di or polyamino hydrocarbylene compounds. The hydrocarbyl or hydrocarbylene groups preferably each 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 mentioned, for example, in EP 0508115 A1 from page 1, line 51 to page 16 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 e.g. dimers, trimers or tetramers. In addition to the polyisocyanates, it is also possible to use isocyanates of the R-NCO (monoisocyanate) type, where R represents a hydrocarbon radical with preferably 5 to 20 carbon atoms.

Preference is given to diureas obtainable from diisocyanates and monoamines or tetraureas obtainable from diisocyanates, monoamine and diamine, each as defined above. 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 produced by the in-situ reaction of the amine and isocyanate components in the base oil.

Optionally, additional inorganic thickeners include bentonites such as montmorillonite (the sodium ions of which are exchanged or partially exchanged by organically modified ammonium ions), aluminosilicates, clays, hydrophobic and hydrophilic silicic acid, possibly together with oil-soluble polymers (e.g. polyolefins , Poly (meth) acrylates, polyisobutylenes, polybutenes or polystyrene copoly mers) 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, silicic acid, and amorphous silicon dioxide, in each case even individually.

Soap or complex soap thickeners based on calcium, lithium or aluminum salts are particularly suitable as organic thickeners. The soap is available e.g. as a reaction product of e.g. calcium hydroxide, lithium hydroxide or aluminum alcoholate with a saturated or unsaturated monocarboxylic acid with 10 to 32 carbon atoms, in particular with 16 to 20 carbon atoms, optionally substituted e.g. by hydroxyl, as an ester or anhydride. Esterified dicarboxylic acid half-amides (C12 - C24) based on terephthalic acid can also be used. The corresponding fats are also referred to here as fen thickeners. The presence of a complexing agent turns the soap into a complex soap. Suitable complexing agents are: (a) the alkali salt (preferably lithium salt), alkaline earth salt (preferably calcium salt) or aluminum salt of a saturated or unsaturated monocarboxylic acid or hydroxycarboxylic acids with 2 to 8, in particular 2 to 4 carbon atoms or a dicarboxylic acid with 2 up to 16, in particular 2 to 12 carbon atoms, each optionally substituted, and / or (b) the alkali and / or alkaline earth 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 as an additive during the base fat manufacture or later. Alternatively, these soaps can also be formed in situ during the manufacture of the fats.

For example, stearate benzoate hydroxyaluminates can be used to make aluminum complex soap thickened greases. Lithium-12-hydroxystearate thickeners are typical representatives of lithium soap fats, calcium-12-hydroxystearate those 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). Soaps or complex soap thickeners and polyurea thickeners are then preferably used together in an amount of 5 to 25% by weight in relation to the polyurea fat composition of claim 1, the polyurea thickener being used at least 1% by weight, preferably at least to 1.5 wt.%, each Weil in relation to the polyurea fat composition.

Solid lubricants such as 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. B. molybdenum disulfide, tungsten disulfide or mixed sulfides based on tungsten, Mo lybdenum, bismuth, tin and zinc, inorganic salts, for example of the 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.

Lignin derivatives such as alkali or alkaline earth lignin sulfonates, in particular calcium lignin sulfonates, can also be used to achieve specific properties, e.g. 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 through the use of 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), ie the organic carbonate is not substituted by a heteroatom. 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 ,. As cyclic, organic carbonates, for example, 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 are used, propylene carbonate being preferred is used.

The organic cyclic carbonate can be added as an additive to the polyurea fat 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 conventional 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.

Customary additives for the purposes 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 are:

• primary antioxidants such as amine compounds (e.g. alkylamines or 1-phenylaminonaphthalene), aromatic amines such as phenylnaphthylamines 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, 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 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 triphenyl thiophosphate, phosphonates (phosphites) such as dioctyl phosphonate, alkyl sulfonates, thio carbamates such as methylene bis (dibutyldithiocarbamate and dithiocarbamate).

• Active ingredients that improve "oiliness" such as C2 to C6 polyols, fatty acids, fatty acid esters or animal or vegetable oils;

• Anti-corrosion agents such as sulfonates such as petroleum sulfonate, dinonylnaphthalene 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 reducer partially with wear protection properties as Organomo- lybdänkomplexe (OMC), molybdenum-di-alkyl-dithiophosphates, molybdenum di-alkyl dithiocarbamates, especially the molybdenum-di-n-butyldithiocarbamate and molybdenum di-alkyldithiocarbamate (Mo2 _m S _n (dialkyl carbonate) 2 with m = 0 to 3 and n = 4 to 1), zinc dithiocarbamate or zinc dithiophosphate; or a trinuclear molybdenum compound of the formula

MOsSkLnQz, in which L are independently selected ligands having organogroups with carbon atoms, as disclosed in US 6172013 B1, in order to make the compound soluble or dispersible in the oil, where n ranges from 1 to 4, k ranges from 4 to 7, Q is selected from the group of neutral electron donor compounds consisting of amines, alcohols, phosphines and ethers, and z is in the range from 0 to 5 and comprises non-stoichiometric values (compare DE 102007048091 ); _ organic acids such as isostearic acid, functional polymers such as oleylamides, organic compounds based on polyether and amide, such as alkyl polyethylene glycol tetradecylene glycol ether, PIBSI (polyisobutylene succinic acid imide) or PIBSA (polyisobutylene succinic acid anhydride), parti-phosphonyl glyceride, parti- alglyceride. The polyurea fat compositions are built up in particular as follows: a) 55 to 95% by weight, in particular 70 to 90% by weight, of the base oil; b) 1 to 20% by weight, in particular 1.5 to 15% by weight, of the polyurea thickener; 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 from the following optional components: 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, of inorganic thickeners, such as amorphous S1O2 or silica; and f) 0 to 20% by weight, in particular 0.1 to 15% by weight, solid lubricants g) 0 to 20% by weight, in particular 1 to 15%, 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 percentages by weight relate to the overall composition and apply independently of one another. A component that is assigned to one of the groups a), b) c) or d) cannot be part of another group a) to d) at the same time. The percentages by weight add up to 100 percent by weight 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 (worked 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 fat composition is generally made by the in-situ reaction of the above amines and isocyanates, preferably in the base oil. According to the method on which the present invention is based for the produc- tion of the polyurea fat composition, a preliminary stage (base fat) is first created by combining at least

- Base oil and amine and isocyanate components and

- heating above 120 ° C, especially above 150 ° C, to produce the base fat,

- Cooling the base fat and adding the additives, preferably below 100 ° C or even below 80 ° C.

If another thickener component, such as the soap or complex soap thickener, is added to the polyurea base fat, this is done, for example, after the base fat has been prepared, 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 approx Soap or the calcium complex soap).

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, further 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 the base fat is preferably transferred from the reactor to a separate stirred tank for cooling and mixing in the possibly further constituents.

What applies to pure polyurea fats can also be applied to mixed thickener systems with polyurea thickeners. The production of polyurea fats with lime soap content (simple and complex soaps of hydroxymonocarboxylic acids, for example 12-hydroxystearic acid) is disclosed in US Pat. No. 5,084,193, for example. The process of US 5084193 can also be used to produce the polyurea greases 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 also constant velocity universal 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 lubricating grease that is compatible with sealing materials made of fluorinated elastomers. The selection of fluorinated elastomers as materials for seals of various designs is often dictated by the conditions of use such as high temperature 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. For crosslinking, depending on the desired fluoroelastomer properties, e.g. diamine, bisphenolic or peroxide crosslinks are used. Fluoro rubbers are those rubbers that have vinylidene (di) fluoride (VDF) as one of their monomers as a common feature. The two most important types of fluororubbers are copolymers of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) and terpolymers of VDF, HFP and tetrafluoroethylene (TFE). Typical commercial products for fluoro rubbers are under the brands Viton®, Tecnoflon®, Dyneon® or Dai-El®. expelled.

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

In addition to the fluororubbers there are other groups of fluorinated Elasto mers such. B. perfluorinated rubber (FFKM), tetrafluoroethylene / propylene rubbers (FEPM) and fluorinated silicone rubbers (FVMQ).

The sealing materials are used in the form of 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, it can be divided into static and dynamic sealing points. Lubrication is particularly necessary for moving parts, so the seals often relate to dynamic sealing points. But the static housing seal, for example from gearboxes as leak protection, is also included as an example of static seals.

The seals are e.g. designed as O-rings or profile rings, radial shaft seals, mechanical seals, stuffing box seals, flat seals, lip seals, wipers, sealing cords. Examples of applications are radial shaft seals for generator shafts, stuffing box seals for pumps, mechanical seals for chemical reactors or bead mills (sealing of 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 roller bearings and plain bearings.

The invention is illustrated below by means of examples, without being restricted to these. The details of the examples and the properties of the greases are given in Tables 1 to 5 below.

Example 1: Production of the 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. 113.4 g of 4,4-methylene-bis-diphenyl diisocyanate were added and the contents of the reaction vessel were heated to 60 ° C. with stirring. 630 g of PAO 8 were placed in a further heatable vessel with a stirrer, and 87.6 g of p-toluidine and 9.0 g of cyclohexylamine were added. The contents of the jar 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 an end 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 grease was homogenized using a colloid mill. Table 1

Description B1-A B1-B B1-C propylene carbonate 0% 0.5% 1.0% D Shore A +15 +11 +2 D weight + 1.2% + 1.3% + 1.1% D 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. Thereafter, 91.5 g of n-octylamine were 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.degree. C. over the course of 2 hours with stirring and then cooled to 60.degree. 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 fat obtained are summarized in Table 2.

Table 2

Description B2-A B2-B B2-C propylene carbonate 0.5% 1% D Shore A +13 +7 +3 D weight + 3.6% + 1.6% + 1.9% D volume + 8.2% + 3.4% + 5.0%

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

369.7 g 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. 94.2 g of 4,4-methylene-bis-diphenyl diisocyanate were added and the contents of the reaction vessel were heated to 60 ° C. with stirring. A mixture of 37.3 g of cyclohexylamine and 47.8 g of n-octylamine was then added dropwise, whereupon the formation of the thickener takes place exothermically. The reaction mixture was heated to a final temperature of 160 ° C. over a period of two hours with stirring. When the final temperature of 160 ° C. was reached, another 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 given. The temperature of 130 ° C was held 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. Then an additive package consisting of amine antioxidants, high-pressure additives, AW additives, non-ferrous metal passivator and corrosion protection additives was added and finally the grease was homogenized using a three-roller chair.

The properties of the resulting polyurea fat containing calcium soap are summarized in Table 3. The dropping point was determined in accordance with DIN ISO 2176.

Table 3

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 DR 60-60000 13 15 8

Drop point 272.7 ° C 270.0 ° C 264.2 ° CD Shore A +8 + 4 +1 D weight + 1.7% + 1.6% + 1.7% D volume + 2.6% + 0 .6% + 2.6% Determination of the compatibility with fluorinated elastomers

The compatibility of the 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 30 mm and a thickness of 2 mm were punched out of an elastomer plate made of SRE-FKM / 2X. The test specimens were stored in the polyurea greases described above at 180 ° C. or 160 ° C. for 7 days and then evaluated.

The evaluation of the fluorinated elastomers took place after wiping off the grease with a clean cloth by: a) Determination of the penetration hardness (Shore A) according to DIN EN ISO 7619-1, whereby the test specimen had a penetration hardness (Shore A) of 78 before the treatment, and b) bending tests by hand.

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

The stabilizing effect of propylene carbonate could be demonstrated in the storage test. With increasing propylene carbonate content, there were no or only slight signs of embrittlement despite the high storage temperature of 180 ° C.

When the propylene carbonate is used in polyurea grease, the fluorinated elastomers have less or no tendency to harden. According to the recommendation of the elastomer manufacturer, greases that cause a change in hardness 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 elastomer concerned.

The results are shown in Table 4. Table 4

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- MDI / Octylamine, together- MDI / p-Toluidine, Cycylohexylamine // Ca- Deposition Cyclohexylamine M Dl / Octylamine 12-HSA

Propylene carbonate

[% By weight] 0 0.5 1 0 0.5 1 0 0.3 1

temperature

[° C] 180 180 160

D Shore A +15 +11 +2 +13 +7 +3 +8 +4 +1 bending test somewhat soft, brittle et flexi- brittle still flexible by hand that hardens flexible flexible breaks something, breaks flexible fluorinated when flexi at Elastomer bending and bending test specimen The addition of 0.5% propylene carbonate in grease B2-B halved the increase in hardness of the FKM elastomer. By adding 1% propylene carbonate (B2-C), the increase could be reduced to a harmless 3 points with regard to the 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 marginal result (+8). By adding 0.3% propylene carbonate (B3-B), the change in hardness could be pushed back into a harmless range. The addition of 1% propylene carbonate (B3-C) left the elastomer almost unchanged with regard to its change in hardness.

Examples 4A and 4B

In addition to the improved compatibility of the polyurea grease composition with fluorinated elastomers, the addition of carbonates can improve the properties in terms of service life and post-hardening behavior. 875.0 grams of Group I oil (paraffinic; 105-110cSt at 40 ° C) and 875.0g of Group II oil (hard-hydrogenated, paraffinic; 105-110cSt at 40 ° C) were placed in a heatable stirrer. 31.5 grams of 4,4-methylene-bis-diphenyl diisocyanate (MDI) were added to this oil mixture. The reactor contents were heated to 55 ° C. with stirring. At 55 ° C., a mixture of 12.5 grams of cyclohexylamine and 16.0 grams of N-octylamine was slowly metered in. The temperature rose to 72 ° C. as a result of the exothermic reaction of isocyanate with the amine mixture. This temperature was held for 30 minutes to complete the formation of the thickener. The reaction mixture was heated to a final temperature of 160 ° C. over the course of 3 hours with constant stirring. 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 the same temperature. The batch was cooled to 60 ° C. with continued stirring, followed by the addition of 10.0 grams of an aminic antioxidant (Irganox L57). The base fat mixture 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 partial batches A and B were then 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 of Group II oil (hard-hydrogenated, paraffinic; 105-110cSt at 40 ° C) were placed in a heatable stirrer. 31.5 grams of 4,4-methylene-bis-diphenyl diisocyanate (MDI) were added to this oil mixture. The reactor contents were heated to 55 ° C. with stirring. At 55 ° C., a mixture of 12.5 grams of cyclohexylamine and 16.0 grams of N-octylamine was slowly metered in. The exothermic reaction of isocyanate with the amine mixture increases the temperature to 72 ° C. This temperature was held for 30 minutes to complete the formation of the thickener. The reaction mixture was heated to a final temperature of 160 ° C. over the course of 3 hours with constant stirring. The reactor contents were then cooled to 135 ° C followed by the addition of 180.0 grams of calcium 12-flydroxistearate. The mixture was stirred for 30 minutes at the same temperature. 20.0 grams (1.0%) of propylene carbonate are added at 135 ° C. with stirring. The batch was then cooled to 80 ° C. and 10.0 grams of an aminic antioxidant (Irganox L57) were added. The batch was then 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 25 ° C 25 ° C 135 ° C

Propylene carbonate

RP-SF / DIN ISO 2137 296 306 293

RP-24h at 25 ° C 283 287 269

/ DIN ISO 2137

RP-24h at 100 ° C 215 221 225

/ DIN ISO 2137

ARP-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

D60-60000 26 18 26

WP60-24h at 100 ° C 283 302 305

/ DIN ISO 2137

AWP 60 -18 -9 +3

(25 ° C vs. 100 ° C)

Drop 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 h 63.2 h

F50 44 h 117.5 h 92.8 h A slight softening of the consistency of the milled penetration WP60 is achieved by adding organic carbonates. The dropping point of the fats is slightly lowered 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 increased temperature (100 ° C) compared to 25 ° C: the resting penetration of fat samples that have been stored for 24 hours (RP-24h) at 100 ° C increases compared to those the 24h stored at 25 ° C were severely reduced, the fats hardened (compare ARP-24h). By adding 1% propylene carbonate, this post-hardening effect could be reduced by around 30%.

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

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

Claims

Claims

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, the organic carbonate having from 4 to 8 carbon atoms, the composition comprising: 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. Polyurea fat 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, particularly preferably 0.5 to 2% by weight, of the organic carbonate.

3. Polyurea fat composition according to claim 1 or 2, characterized in that the composition further 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, of inorganic thickeners; and f) 0 to 20% by weight, in particular 0.1 to 15% by weight, solid lubricants.

4. Polyurea fat composition according to at least one of the preceding claims, characterized in that the composition further comprises: g) 0 to 20% by weight, in particular 1 to 15%, further organic thickeners, in particular soap or complex soap thickeners based on Calcium, lithium or aluminum soaps, especially lithium soaps.

5. Polyurea fat composition according to at least one of the preceding claims, wherein the composition contains no bentonites, no aluminosilicates, no clays, no silica and no amorphous silicon dioxide, and in particular no inorganic thickeners.

6. Polyurea fat composition according to at least one of the preceding claims, wherein the organic carbonate is a cyclic carbonate, in particular propylene carbonate.

7. Polyurea grease composition according to at least one of the preceding claims, characterized in that the composition has 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 Has ISO 2137.

8. Polyurea fat composition according to at least one of the preceding claims, wherein the base oil has a kinematic viscosity of 20 to 2500 mm ² / s, preferably from 40 to 500 mm ² / s, in each case at 40 ° C.

9. Lubrication point comprising the polyurea grease composition according to at least one of the preceding claims and a seal comprising a sealing material, the sealing material consisting of an elastic fluoropolymer.

10. 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 one of claims 1 to 7 in contact with the lubrication point and the seal.

11. Lubrication point according to claim 9 or component according to claim 10, wherein the elastic fluoropolymer is a fluororubber elastomer.

12. Lubrication point according to claim 9 or component according to claim 10, wherein the seal is an O-ring or profile ring, a radial shaft seal, a mechanical seal device, a gland seal, a flat seal, a lip seal, a scraper or a sealing cord.

13. Component according to claim 10, wherein the component is a shaft, a transmission, a piston, a joint, a roller bearing or a plain bearing.

14. Use of the polyurea grease composition according to one of claims 1 to 7 for a lubrication point or a component according to claims 9 to 13.

15. A method for producing the polyurea fat composition according to at least one of claims 1 to 8, wherein the method comprises the production of a polyurea in at least a portion of the base oil in the heat and the addition of the organic carbonate after production of the polyurea in the base oil and takes place on cooling to a temperature between 100 ° to 135 ° C.