JP2013060551A - Lubricating grease composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lubricating grease composition that prevents or at least reduces the observed fixation of a urea-containing lubricating grease.SOLUTION: The lubricating grease composition comprises one base oil or a mixture from a base oil mixture. The lubricating grease composition further contains urea as a thickener component and contains one or plural kinds of ionic liquid, other additive and solid lubricant. The total volume of the ionic liquid is <1%.

Description

  The present invention relates to a base oil mixture based on oils having a viscosity (ISO VG 2 to ISO VG 1500) customary for industrial lubricants, one or more ionic liquids and at least partly a polyurea Lubricating grease composition comprising a compound-based thickener and conventional additives, even at normal operating temperatures from 60 ° C. to 260 ° C., especially at high operating temperatures from over 180 ° C. to 260 ° C. The present invention relates to a lubricating grease composition that can be used even at a low temperature of −60 ° C.

  The development of new lubricants must be accompanied by a general redevelopment of technology that places new and higher demands on lubricant compositions. These requirements are no longer met by known lubricant compositions based on mineral and / or synthetic oils.

  Lubricants are used in automotive technology, transport technology, mechanical engineering, office technology and industrial equipment and equipment, but are also used in household and entertainment electronics.

  In rolling and sliding bearings, the lubricant provides a lubricating film configuration that transmits the load across the sliding or rotating members. Thereby, it is achieved that the metal surfaces are not in contact with each other and therefore no wear occurs. Therefore, the lubricant must meet high demands. For example, in the case of bearings working in extreme operating conditions such as very high or very low speeds, high temperatures caused by high speeds or external heat, very low temperatures, eg cold working environments or aviation and space flight This applies to the very low temperatures that occur when used in Similarly, it is desirable that modern lubricants can be used under so-called clean room conditions to avoid indoor contamination due to wear or lubricant consumption. Furthermore, in the use of modern lubricants, it should be avoided that they evaporate and "veracken", ie become solid immediately after use and no longer exhibit a lubricating action.

  Established grease types are urea thickened greases that may be based on any conventional base oil type. In particular, in combination with synthetic esters, greases that can be used at high temperatures (inspected by FE9, DIN 51825) and have excellent low noise properties can be obtained, for example as described in EP 0 902 828 B1. Further performance enhancement can be achieved, for example, by combination with perfluoropolyether present in the grease as an additional liquid phase. For example, it is disclosed in EP 0902828 B1. In practice, such greases have proven effective for use in grooved ball bearings. However, in the case of large bearing specifications, in the case of roller bearings, or even in the case of very high temperature use, re-lubricating has to be done and the limit in efficiency is clear. Strong solidification of grease is also observed, especially in regions with low shear, which can lead to poor bearing management and can lead to premature failure, and can also plug re-lubricating conduits . This strong solidification of the grease is then due to the enhanced orientation of the thickener molecules, possibly coupled with the base oil oxidation products, rather than due to too high evaporation of the oil.

  The use of ionic liquids (also called IL (= Ionic Liquid)) in lubrication technology has been intensively investigated for several years. This is because a wide range of use can be provided by changing the cation or anion. The ionic liquid is a so-called molten salt which is preferably liquid at room temperature or has a melting point below 100 ° C. by definition. Known cation / anion combinations that give rise to ionic liquids are, for example, combinations of dialkylimidazolium, pyridinium, ammonium and phosphonium with organic anions such as sulfonates, imides, methides, and also dialkylimidazolium, pyridinium, ammonium and phosphonium. In combination with inorganic anions such as halogenides and phosphates, where any further cation and anion combinations capable of achieving a low melting point are also conceivable. Ionic liquids may have very low vapor pressures, are not flammable, are often thermally stable to above 260 ° C., and may still be lubricious.

  WO 2006/077082 describes a method for sealing a rotating shaft using an end face seal and the use of an ionic liquid as a component of a blocking liquid for the end face seal for sealing the rotating shaft. Said blocking liquid is used to additionally seal the rotating shaft. Known blocking liquids are water or oil, whose behavior is improved with respect to interaction with the surroundings of equipment having a high tightness requirement by the use of ionic liquids.

  DE 102004033021 A1 describes the use of ionic liquids as working liquids, whereby the compressibility of the liquid pressure transmission medium is reduced and thus the energy transmission efficiency of the hydraulic system is improved. .

  From DE 102005007100 A1, processing or working equipment is known which uses an ionic liquid as the operating liquid. This ionic liquid is also used as a lubricating liquid, a blocking liquid, a sealing liquid, a pressure transmission liquid, etc., even in a range where it is used as an operating liquid.

  DE102008024284A1 describes a lubricant composition containing a base oil mixture, an ionic liquid, a thickener and an additive. The lubricant composition can be used at a high temperature or a low temperature.

  Furthermore, lubricant compositions are known which consist almost exclusively of ionic liquids and thereby take advantage of the properties of the preferred ionic liquids. It is described, for example, in WO 2006/109652 A1.

  It is also known to provide greases for vacuum applications with the main component ionic liquid. The grease is known from JP 2005/154755 A. However, such lubricating grease is not suitable for use in the high temperature region and the low temperature region. A further disadvantage of the greases is the very high cost.

  The effects of ionic liquids at low concentrations in lubricating greases are not well known and not described, and are described only for the observed effects on friction. Here, the ionic liquid acts with the metal surface to be lubricated and partially forms a reaction layer. The effect of ionic liquids on the thickener structure is not known.

European Patent No. 0902828 B1 WO2006 / 077082 DE102004033021 A1 DE102005007100 A1 DE102008024284 A1 WO2006 / 109652 A1 JP 2005/154755 A

  It is an object of the present invention to provide a lubricating grease composition that reduces or at least reduces the observed solidification of urea-containing lubricating greases, and thereby guarantees performance in the applications mentioned.

  Surprisingly, it has now been found that a small amount of ionic liquid can suppress and delay its solidification action at high temperatures. The rationale seems to be the solubility properties of ionic liquids in strongly polar substances, which can affect the enhanced orientation that has been discussed in the topic of thickener molecules. The low evaporation tendency of ionic liquids can guarantee a sufficiently long working time. Based on the small amount of metering, the influence of the ionic liquid on, for example, material compatibility is less and the cost for the lubricant is relatively modestly affected.

  The base oil mixture may be a synthetic oil, a mineral oil and / or a natural oil. These oils can be used individually or in combination depending on the application.

Synthetic oils are derived from esters of aliphatic or aromatic dicarboxylic acids, tricarboxylic acids or tetracarboxylic acids and C ₇ -C ₂₂ -alcohols present as one or as a mixture, alone or in any mixture, From polyphenyl ethers or alkylated diphenyl ethers, trimethylolpropane, pentaerythritol or dipentaerythritol and esters of aliphatic C ₇ -C ₂₂ -carboxylic acids to C ₁₈ with C ₇ -C ₂₂ -alcohols. -From dimer acid esters, selected from complex esters. Furthermore, the synthetic oil is selected from poly-α-olefins, alkylated naphthalenes, alkylated benzenes, polyglycols, silicone oils, perfluoropolyethers, wherein the base oils need not necessarily be miscible, As such, the grease may contain more than one liquid phase.

  Mineral oils can be selected from paraffinic, naphthenic, aromatic hydrocracked oils; Gas to Liquid (GTL) liquids. GTL is a gas-to-liquid process and describes a method for producing fuel from natural gas. Natural gas is converted to syngas by steam reforming, which is then converted to fuel using a catalyst by Fischer-Tropsch synthesis. The catalyst and process conditions control the type of fuel, so it controls whether gasoline, kerosene, diesel or oil is produced. Similarly, according to the Coal-to-Liquid (CTL) method, coal can be used as a raw material, and in the Biomass-to-Liquid (BTL) method, biomass can be used as a raw material. Can be used.

  As natural oil, triglycerides derived from animals / plants processed by a known method such as hydrogenation can be used. A particularly preferred triglyceride oil is a triglyceride oil having a high oleic acid content. The vegetable oils typically used here with high oleic acid content are safflower oil, corn oil, rapeseed oil, sunflower oil, soybean oil, linseed oil, peanut oil, bladderer oil, meadow foam oil And coconut oil.

Suitable cations for the ionic liquid include quaternary ammonium cations, phosphonium cations, imidazolium cations, pyridinium cations, pyrazolium cations, oxazolium cations, pyrrolidinium cations, piperidinium cations, thia A zolium cation, a guanidinium cation, a morpholinium cation, a trialkylsulfonium cation or a triazolium cation are shown, which are [PF ₆ ] ⁻ , [P (C ₂ F ₅ ) ₃ F ₃ ] ^−. , [BF ₄ ] ⁻ , [CF ₃ CO ₂ ] ⁻ , [CF ₃ SO ₃ ] ^{− and} higher homologues thereof, [C ₄ F ₉ —SO ₃ ] ⁻ or [C ₈ F ₁₇ —SO ₃ ]. ^- and higher perfluoroalkyl sulfonate, [(CF ₃ SO ₂ ) ₂ N] ⁻ , [(CF ₃ SO ₂ ) (CF ₃ COO) N] ⁻ , [R ⁴ —SO ₃ ] ⁻ , [R ⁴ —O—SO ₃ ] ⁻ , [R ⁴ —COO ^{] -, Cl -, Br -} , [NO 3] -, [N (CN) 2] -, [HSO 4] -, PF (6-x) R 6 x or _{^{[R 4 R 5 PO 4]}} - from Wherein the radicals R ⁴ and R ⁵ are independently of each other hydrogen; linear or branched, saturated or unsaturated, aliphatic or alicyclic An alkyl group having 1 to 20 carbon atoms of the formula; a heteroaryl group, a heteroaryl-C ₁ -C ₆ -alkyl group, having 3 to 8 carbon atoms in the heteroaryl group; and N, at least one heteroatom selected from O and S, it C ₁ -C ₆ - alkyl and / or halogen At least one optionally substituted groups have a group from the atom; an aryl group, an -C ₁ -C ₆ - an alkyl group having 5 to 12 carbon atoms in the aryl group, it is at least Selected from groups optionally substituted by one C ₁ -C ₆ -alkyl group; R ⁶ may be perfluoroethyl or a higher perfluoroalkyl group, x is 1-4, and generally x is 3. However, other combinations are possible.

The thickener is a diisocyanate, preferably 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanatodiphenylmethane, 2,4'-diisocyanatodiphenylmethane, 4,4 '-Diisocyanatodiphenyl, 4,4'-diisocyanato-3,3'-dimethyldiphenyl, 4,4'-diisocyanato-3,3'-dimethylphenylmethane (these can be used alone or in combination); An amine / diamine of the general formula (H ₂ N) _x R, wherein x is 1 or 2 and R is an aryl, alkyl or alkylene group having 2 to 22 carbon atoms; These may be present alone or in combination) in which case metal soap, metal complex soap, bentonite, Locate powder, polytetrafluoroethylene (PTFE), polyamide, it may be present additional thickener selected from polyimide.

  Furthermore, the lubricating grease composition according to the present invention is a usual additive for corrosion, a usual additive for oxidation, and an additive for protection against the influence of metal, including a chelate compound, a radical scavenger, a UV stabilizer, Additives present as reaction layer formers and inorganic or organic solid lubricants such as polyimide, polytetrafluoroethylene (PTFE), graphite, metal oxides, boron nitride, molybdenum disulfide and phosphate contains. In particular, additives in the form of phosphorus-containing compounds and sulfur compounds, such as zinc dialkyldithiophosphates, borate esters are used as anti-wear / extreme pressure additives, and aromatic amino, phenol, sulfur compounds are used as antioxidants. Used, metal salts, esters, nitrogen-containing compounds and heterocyclic compounds are used as corrosion inhibitors, glycerin monoesters or glycerin diesters are used as friction protectants, and polyisobutylene and polymethacrylates are used as viscosity improvers. Is done.

The lubricating grease composition according to the present invention comprises a 39-96.9% base oil mixture, less than 1% by weight ionic liquid, 3-50% by weight thickener, 0.1-10% by weight additives. contains. This lubricating grease composition, as measured at 40 ° C., the viscosity of the base oil is in the range of 1.98~1650mm ² / s, the viscosity of the ionic liquid, the range of 1.98~1650mm ² / s It is.

  The lubricating grease composition according to the invention mixes a base oil thickened with diurea and / or polyurea with an ionic liquid and subsequently homogenizes, for example by means of a high-pressure homogenizer and / or a three-roll mill (Drewalzenstuhl) Or by mixing base oil and ionic liquid, in this mixture thickening in situ by synthesis of polyurea compound or diurea compound, followed by homogenization with high pressure homogenizer and / or three roll machine It is obtained by doing. In the case of a grease using a mixed thickener, for example, a grease using calcium soap in addition to a urea thickener, the same can be done in principle, but the ionic liquid is preferably added later. This is because aqueous alkaline solutions can react with many common cations.

FIG. 1 shows the shear viscosity (mPas) in Examples 1 to 3 compared with the shear viscosity in Example 7 in an aluminum pan test. FIG. 2 shows the shear viscosity (mPas) in Examples 4-6 compared to the shear viscosity of Example 7 in an aluminum pan test. FIG. 3 shows the evaporation loss (based on DIN 58397-T1) and the development of shear viscosity (% or mPas) of Examples 1 to 3 compared to Example 7.

  The invention will now be described in detail by the following examples.

For the various lubricant compositions listed below, rolling bearing greases composed of synthetic esters, aromatic diisocyanates and aliphatic amines were used as the base oil. Trimellitic acid esters with alcohols sections (Alkoholschnitt) C ₉ ~C ₁₁ used as synthetic esters, using MDI as the isocyanate, and using octylamine / oleylamine as monoamine.

  The ionic liquid was mixed with non-homogenized grease that already contained all other ingredients such as oils, thickeners and additives and homogenized by a three roll machine.

  As the ionic liquid, 1-ethyl-3-methyl-imidazolium ethyl sulfate (EMIMethylsulfat, trade name Ecoeng 212) and N-ethyl-3-methylpyridinium nonafluorobutane sulfonate (EMPYnonaflat) at a concentration of 0.3%, Used at 0.6% and 0.9%. The grease exhibits an NLGI penetration in the range of 2-3.

  In addition to data indicating the presence of functional lubricating greases, especially ionic liquids that do not destroy the structure, such as consistency, dropping point and oil separation (Oelabcheidung), blocking of urea grease solidification under thermal load Two surveys were conducted to show this. For the evaporation loss measurement at 150 ° C. based on DIN 58397-T1, two small dishes were filled for each grease, heat treated at the same time, and removed from the drying chamber for measurement after the time indicated in the table. The one dish was weighed and the evaporation loss was measured thereby. A small sample was removed from another dish and the shear viscosity was measured in a rheometer (based on DIN 51810; 25 ° C., 300 1 / s shear gradient).

  In the second test, the so-called “Alumina dish test” was used at a heat load of 160 ° C. For this purpose, first the shear viscosity of the grease that has not yet been loaded is measured. In an aluminum pan with a diameter of about 50 mm and a height of about 15 mm, apply the grease to be tested as homogeneously and flatly as possible to a height of three quarters of the pan. Then close the dish with a tight lid. The closed pan is subsequently placed on the oven plate and loaded at an elevated temperature in the furnace. After the time indicated in the table, the shear viscosity of the grease is measured.

The shear viscosity is measured at 300 s ⁻¹ ; 25 ° C.

table

  The results shown in the table show that, with the addition of ionic liquid, the consistency is hardly affected, it is not so high or low with respect to the dropping point, and the dropping point clearly remains above 200 ° C. Is shown.

  For the use of the lubricating grease composition according to the invention in roller bearings, it could be shown that the oil separation is partially enhanced, but the oil separation still remains sufficiently low. Since the effect of oil separation was investigated for a longer time, it was confirmed that the insidious destruction of the grease structure did not occur.

  The effect on evaporation was investigated as well, and it could be shown that no increase in evaporation occurred when using EMPYnonaflat, or a slight increase in evaporation occurred when using ECOENG 212. In addition, an apparently lower shear viscosity was revealed in the evaporation experiments.

  In closed bearings, especially ECOENG 212 resulted in a lower shear viscosity, for example it could be shown by an aluminum pan test.

Claims (6)

  Lubricating grease composition comprising one base oil or a mixture from one base oil mixture, containing urea as a thickener component, one or more ionic liquids and other additives And the lubricating grease composition comprising a solid lubricant, wherein the total amount of the ionic liquid is less than 1%. The thickener component is a diisocyanate, preferably 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanatodiphenylmethane, 2,4'-diisocyanatodiphenylmethane, 4, 4'-diisocyanatodiphenyl, 4,4'-diisocyanato-3,3'-dimethyldiphenyl, 4,4'-diisocyanato-3,3'-dimethylphenylmethane (these can be used alone or in combination) and An amine or diamine of the general formula (H ₂ N) _x R, wherein x is 1 or 2 and R is an aryl, alkyl or alkylene group having 6 to 22 carbon atoms (These are present alone or in combination) and are selected from the group consisting of reaction products, and additionally as other thickener components, Genus soap, metal complex soaps, bentonite, silicate powder, polytetrafluoroethylene (PTFE), polyamide, contains polyimide, lubricating grease composition according to claim 1. The one type of base oil or one type of base oil mixture is selected from the group consisting of oils having a viscosity conventionally used in industrial lubricants and mineral oils, synthetic oils and natural oils. present in or any mixture as ingredients, aromatic or aliphatic dicarboxylic acids, tricarboxylic acids or tetracarboxylic acids, C ₇ -C ₂₂ exist as one or mixture - an ester of an alcohol, poly From phenyl ether or alkylated diphenyl ether, trimethylolpropane, pentaerythritol or dipentaerythritol and an ester of an aliphatic C ₇ -C ₂₂ -carboxylic acid to C ₁₈ -with C ₇ -C ₂₂ -alcohol. Selected from dimer acid esters, complex esters, or poly-α-olefins, alkylated naphthalenes, Selected from killed benzene, polyglycol, silicone oil, perfluoropolyether, wherein the base oil need not necessarily be miscible, so that the grease may contain more than one liquid phase The mineral oil is a paraffinic, naphthenic, aromatic hydrocracked oil; gas-to-liquid (GTL) liquid, coal-to-liquid (CTL) liquid and biomass-to-liquid (BTL) Selected from liquids, the natural oil is an animal / plant derived triglyceride processed by hydrogenation, the triglyceride selected from a triglyceride oil having a high oleic acid content and a vegetable oil having a high oleic acid content Are safflower oil, corn oil, rapeseed oil, sunflower oil, soybean oil, linseed oil, peanut oil, Raddapoddo oil is selected from meadowfoam oil and coconut oil, lubricating grease composition according to claim 1. An ionic liquid or a mixture of a plurality of ionic liquids has a cation of a quaternary ammonium cation, phosphonium cation, imidazolium cation, pyridinium cation, pyrazolium cation, oxazolium cation, pyrrolidi An anion of an ionic liquid that is a cation, a piperidinium cation, a trialkylsulfonium cation, a thiazolium cation, a guanidinium cation, a morpholinium cation, or a triazolium cation, [PF ₆ ] ⁻ , [ P (C ₂ F ₅ ) ₃ F ₃ ] ⁻ , [BF ₄ ] ⁻ , [CF ₃ CO ₂ ] ⁻ , [CF ₃ SO ₃ ] ^{− and} higher homologues thereof, [C ₄ F ₉ —SO ₃ ] ^- or _{[C 8 F 17 -SO 3]} - and higher perfluoroalkyl sulfonate, [(CF ₃ SO ₂ ) ₂ N] ⁻ , [(CF ₃ SO ₂ ) (CF ₃ COO) N] ⁻ , [R ⁴ —SO ₃ ] ⁻ , [R ⁴ —O—SO ₃ ] ⁻ , [R ⁴ —COO] ⁻ , Cl ⁻ , Br ⁻ , [NO ₃ ] ⁻ , [N (CN) ₂ ] ⁻ , [HSO ₄ ] ⁻ , PF _(6-x) R ⁶ _x or [R ⁴ R ⁵ PO ₄ ] ^−. An ionic liquid which is an anion selected from wherein the groups R ⁴ and R ⁵ are, independently of one another, hydrogen; linear or branched, saturated or unsaturated, aliphatic or fatty A cyclic alkyl group having 1 to 20 carbon atoms; a heteroaryl group, a heteroaryl-C ₁ -C ₆ -alkyl group, having 3 to 8 carbon atoms in the heteroaryl group and N, having at least one heteroatom from O and S, it C ₁ -C ₆ - alkyl and / or selected from a halogen atom At least one optionally substituted group group is, an aryl group, an -C ₁ -C ₆ - an alkyl group having 5 to 12 carbon atoms in the aryl group, it is at least 1 The ionic liquid selected from the groups optionally substituted by one C ₁ -C ₆ -alkyl group, wherein R ⁶ may be perfluoroethyl or a higher perfluoroalkyl group and x is 1-4 The lubricating grease composition according to claim 1, selected from:   The anion of the ionic liquid is selected from phosphates, sulfates and sulfonates, wherein the sulfonate may be unfluorinated, partially fluorinated or fully fluorinated. The lubricating grease composition described.   The lubricating grease composition according to any one of claims 1 to 5 in a roller bearing, in a ball bearing, in particular in a ball bearing with a diameter of 100 mm or more, in a rolling bearing, in particular in a rolling bearing that must be re-lubricated. Use to use.

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