Grease composition

Abstract

To provide a grease having excellent shear stability in the presence of water and excellent rust prevention performance even in an environment where water is mixed and shear is applied.SOLUTION: A grease composition comprises a base oil, a di-urea compound as a thickener, and at least one wax selected from the group consisting of rice wax, lanolin wax, carnauba wax, and castor wax.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a grease composition suitable for use in an environment where water may be present or where humidity is high and where shear stress is applied. [Background technology]

[0002] When water gets mixed into grease, it softens and leaks, so it is necessary to improve the water resistance of the grease itself. Greases used in the work roll bearings of hot rolling mills in steelmaking facilities are exposed to large amounts of cooling water and are subjected to strong shear, so they must have excellent water shear stability. Greases used in the rolling bearings of air conditioner fan motors or ventilation fans are used in environments with high humidity and are subject to shear, so they must have excellent water shear stability. Greases used in the rolling bearings of automobile hub units are required to have excellent water-containing shear stability because they are used in environments where they are exposed to water contamination during car washes, rainwater, and when driving on rough roads and are subject to shear stress. In particular, greases used in automotive rack and pinion gears, worm gears in electric power steering, and worm gears in power window motors are required to have excellent water-containing shear stability because they are used in environments where water may be mixed in due to weather conditions and they may be subjected to shear stress. Non-Patent Document 1 reports that when a grease consisting only of mineral oil and a diurea thickener was tested using a tester (ASTM D 1831) for evaluating mechanical shear stability under conditions of 10 wt% water content and 80°C, it became fluid. In order to solve the problem of water resistance, when a diurea compound is selected as a thickener, a method has been reported in which one metal salt compound selected from the group consisting of basic metal sulfonates, basic metal salicylates, and basic metal phenates is included (Patent Document 1). Another method is to use a component with excellent water absorption such as barium sulfate as the thickener (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-053884 A [Patent Document 2] JP 2016-121336 A [Non-patent literature]

[0004] [Non-Patent Document 1] Tribologist Vol. 35 No. 5 (1990) 343-348 Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, an object of the present invention is to provide a grease composition having excellent water-containing shear stability. [Means for solving the problem]

[0006] According to the present invention, there is provided the following grease composition: 1. Base oil, Diurea compounds as thickeners, and A grease composition comprising at least one wax selected from the group consisting of rice wax, carnauba wax, lanolin wax, and castor wax. 2. The grease composition according to claim 1, wherein the wax is rice wax or carnauba wax. 3. The grease composition according to 1 above, wherein the wax is rice wax. 4. The grease composition according to any one of 1 to 3 above, wherein the diurea compound contains a diurea compound represented by the following formula (1): R 1 -NHCONH-R 2 -NHCONH-R 3 (1) (In the formula, R 2 represents an aromatic hydrocarbon group having 6 to 15 carbon atoms, R 1 and R3 may be the same or different and represent an aliphatic hydrocarbon group having 8 to 20 carbon atoms or an aromatic hydrocarbon group having 6 to 15 carbon atoms; R 1 and R 3 The proportion of aliphatic hydrocarbon groups in the total is 40 to 100 mol %.) 5. The grease composition according to any one of 1 to 4 above, wherein the diurea compound contains a diurea compound represented by the following formula (1): R 1 -NHCONH-R 2 -NHCONH-R 3 (1) (In the formula, R 2 represents an aromatic hydrocarbon group having 6 to 15 carbon atoms, R 1 and R 3 may be the same or different and are aliphatic hydrocarbon groups having 8 to 20 carbon atoms.) 6. The grease composition according to any one of 1 to 5 above, further comprising a rust inhibitor. 7. The grease composition according to 6 above, wherein the rust inhibitor comprises at least one of a succinic acid derivative, a metal sulfonate, and an organic acid metal salt. 8. The grease composition according to 6 above, wherein the rust inhibitor is at least one selected from the group consisting of dodecenylsuccinic anhydride, alkenylsuccinimide, zinc dinonylnaphthalenesulfonate, and sodium sebacate. 9. The grease composition according to 6 above, wherein the content of the rust inhibitor is 0.01 to 5 mass % based on the total mass of the composition. 10. The grease composition according to any one of 1 to 9 above, which is for use in rolling bearings or gears. Effect of the Invention

[0007] The grease composition of the present invention has excellent shear stability even when mixed with water. The reason why the water-containing shear stability is improved by the present invention can be explained in principle as follows. That is, the diurea-based thickener, which is a grease component, exists as fine particles in the base oil, and the base oil is held by the capillary force of the network structure composed of these particles, forming a semi-solid or solid grease. When the grease is subjected to shear, the network structure of the thickener is destroyed and the grease softens. In particular, when water is mixed into aliphatic diurea grease, the oil film thickness is significantly reduced and shear softening tends to be promoted. Looking at this at the crystal level, as described in Non-Patent Document 1, the crystal form immediately after the reaction of isocyanate and amine, which are the raw materials of the diurea thickener, is a stable α type, and undergoes a phase transition to a metastable β type during the temperature rise in the grease manufacturing process. When water-containing shear is applied to the diurea grease that has undergone phase transition, it returns to the α type before the phase transition. While α-type tends to form clumps as a whole, β-type, which is a thin, long, fibrous particle, has a greater ability to retain base oil through capillary forces and can maintain sufficient hardness as a grease. In other words, when the crystal form returns to α-type due to hydrous shear, this means that the grease softens. Without being bound by any theory, in the present invention, it is presumed that at least one wax selected from the group consisting of rice wax, carnauba wax, lanolin wax, and castor wax plays a role in preventing the diurea thickener from returning to the molecular arrangement (α type) before the phase transition, and as a result, the grease composition of the present invention has excellent water-containing shear stability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] <Base oil> The type of base oil used in the present invention is not particularly limited. For example, various synthetic oils such as mineral oils such as naphthenic and paraffinic, synthetic hydrocarbon oils such as polyalphaolefins (PAO) and polybutene, ether-based synthetic oils such as alkyl diphenyl ether and polypropylene glycol, ester-based synthetic oils such as diester and polyester, silicone oil, and fluorinated oil can be mentioned. The synthetic oil may be a so-called biomass oil produced from biological resources derived from animals and plants. For example, biomass ester oils synthesized from various fatty acids and alcohols using vegetable oils as raw materials, and biomass hydrocarbon oils using vegetable oils such as palm oil, corn oil, and soybean oil can also be used. The base oil may be used alone or in a mixture of two or more types. The kinematic viscosity of the base oil of the present invention at 40° C. is, for example, 17 to 600 mm 2 / s. The content of the base oil in the composition of the present invention is preferably 70 to 97 mass%, more preferably 80 to 96 mass%, and even more preferably 85 to 95 mass%, based on the total mass of the composition. By including the base oil in such a range, it is possible to ensure lubricity at the application site of the grease composition.

[0009] <Thickener> The thickener used in the present invention is a diurea compound, which can be represented by the following formula (1). R 1 -NHCONH-R 2 -NHCONH-R 3 (1) In the formula, R 2 represents an aromatic hydrocarbon group having 6 to 15 carbon atoms, R 1 and R 3 may be the same or different and represent an aliphatic hydrocarbon group having 8 to 20 carbon atoms, an aromatic hydrocarbon group having 6 to 15 carbon atoms, or a cyclohexyl group. Diurea compounds include: - Aromatic-aliphatic urea compounds, in which the starting amine is a mixture of aromatic and aliphatic amines; - Aromatic urea compounds, in which the raw amine is an aromatic amine; - Aliphatic urea compounds in which the raw amine is an aliphatic amine; - Alicyclic urea compounds in which the raw amine is an alicyclic amine; - cycloaliphatic-aliphatic urea compounds in which the starting amine is a mixture of cycloaliphatic and aliphatic amines, or - A combination of two or more of these may be included. Among these, aromatic-aliphatic urea compounds, aliphatic urea compounds, and alicyclic-aliphatic urea compounds are preferred. When the raw amine is a mixture, the resulting diurea compound is also a mixture. The diurea compound is represented by the formula (1), 1 and R 3 may be the same or different and represent an aliphatic hydrocarbon group having 8 to 20 carbon atoms or an aromatic hydrocarbon group having 6 to 15 carbon atoms; R 1 and R 3 It is preferable that the diurea compound contains an aliphatic hydrocarbon group in a proportion of 40 to 100 mol % of the total. The diurea compound is represented by the formula (1), 1 and R 3 However, they may be the same or different, and it is also preferable to contain a diurea compound which is an aliphatic hydrocarbon group having 8 to 20 carbon atoms.

[0010] The worked penetration of the grease composition of the present invention is preferably 180-400. The content of the thickener in the composition of the present invention may be an amount suitable for adjusting the consistency to the above range, for example, 2.0 to 25% by mass based on the total mass of the composition. In this specification, the term "consistency" refers to the 60-stroke worked consistency measured according to JIS K 2220 7.

[0011] <Wax> The wax used in the present invention is at least one selected from the group consisting of rice wax, carnauba wax, lanolin wax, and castor wax. Rice wax or carnauba wax is particularly preferred. In this specification, the term "wax" refers to an organic substance having an alkyl group that is solid or semi-solid at room temperature (25°C), melts in a temperature range of 35°C to about 110°C, and has a low melt viscosity. Rice wax refers to a wax obtained by refining wax oil separated during refining rice bran and rice oil, and has a CAS number of 8016-60-2. Rice wax is mainly composed of esters of fatty acids (C16 (about 5%), C22 (about 20%), C24 (about 60%), and the remainder is others) and alcohol. Rice wax preferably has an acid value of 15 or less, and a saponification value of 60 to 100 or an iodine value of 20.0 or less. That is, partially saponified rice wax (CAS number of Ca partially saponified rice wax is 1850357-57-1) can be used, or hydrogenated rice wax can be used. This improves shear stability when hydrated. The ratio of the fatty acids can be measured by gas chromatography. The acid value can be measured according to ISO 2114. The saponification value can be measured according to ISO 3681. The iodine value can be measured according to the Standard Methods for Analysis of Fats, Oils and Related Materials. Among these, rice wax is preferred, and in particular, rice wax having an acid value of 15 or less and a saponification value of 60 to 100, or rice wax having an acid value of 15 or less and an iodine value of 20.0 or less is preferred.

[0012] Carnauba wax refers to wax extracted and refined from the leaves of the carnauba palm tree, and its CAS number is 8015-86-9. Carnauba wax is mainly composed of esters of fatty acids (C20 (about 7%), C22 (about 7%), C24 (about 25%), C26 (about 10%), C28 (about 15%), C30 (about 4%), C32 (about 6%), the remainder being others) and alcohol. Carnauba wax preferably has an acid value of 12 or less, a saponification value of 70 to 100, and an iodine value of 4 to 15 or less. This improves shear stability when water is contained. The ratio of the fatty acids can be measured by gas chromatography analysis. The acid value can be measured according to ISO2114. The saponification value can be measured according to ISO3681. The iodine value can be measured according to the Standard Method for Analysis of Fats, Oils and Related Compounds. The content of the wax in the composition of the present invention is preferably 0.1 to 5.0 mass%, more preferably 0.1 to 3.0 mass%, and further preferably 0.2 to 1.5 mass%, based on the total mass of the composition. By including the wax in such a range, it is possible to improve the water-containing shear stability.

[0013] <Optional Additives> In addition to the above components, the grease composition of the present invention may further contain additives that are commonly used in grease compositions. Examples of such optional additives include rust inhibitors, antioxidants, metal corrosion inhibitors, antiwear agents, extreme pressure agents, and solid lubricants. Among these, it is particularly preferable to contain a rust inhibitor. As long as it does not inhibit the effect of the grease composition of the present invention, another wax may be contained. However, the grease composition of the present invention does not contain lithium soap.

[0014] <Rust inhibitor> The rust inhibitors that can be used in the present invention include alkaline earth metal phenates or salicylates, partial organic acid esters, succinic acid derivatives, and metal sulfonate compounds. These can be used alone or in combination. In this specification, the term "succinic acid derivatives" is a concept that includes unsubstituted succinic acid. The succinic acid derivative is preferably succinic acid, dodecenylsuccinic anhydride or alkenylsuccinimide, more preferably dodecenylsuccinic anhydride or alkenylsuccinimide. As the metal sulfonate compound, alkaline earth metal sulfonates such as zinc sulfonate or calcium sulfonate are preferred, with zinc dinonylnaphthalenesulfonate being more preferred. Of these, succinic acid derivatives are preferred, with dodecenylsuccinic anhydride being more preferred. The content of the rust inhibitor in the composition of the present invention is preferably 0.01 to 2 mass%, more preferably 0.1 to 1.0 mass%, and further preferably 0.1 to 0.5 mass%, based on the total mass of the composition. By including the rust inhibitor in such a range, the rust prevention property and water-containing shear stability are improved.

[0015] The antioxidants include amine-based, phenol-based, quinoline-based, sulfur-based, zinc dithiophosphate, and the like. Examples of the metal corrosion inhibitor include thiadiazoles, benzimidazoles, and benzotriazoles. Examples of anti-wear agents and extreme pressure agents include phosphorus-based compounds (tricresyl phosphate, tri-2-ethylhexyl phosphate, etc.), sulfur-based compounds (dibenzyl disulfide, various polysulfides, etc.), sulfur-phosphorus compounds (triphenyl phosphorothioate), organometallic extreme pressure agents (dialkyl dithiophosphoric acid salts of Zn, Mo, Sb, Bi, etc., dialkyl dithiocarbamic acid salts of Zn, Mo, Sb, Ni, Cu, Bi, etc.), and others (ashless dithiocarbamates, ashless dithiophosphate carbamates). Examples of solid lubricants include molybdenum disulfide, graphite, polytetrafluoroethylene, and melamine cyanurate. Examples of waxes other than the essential components include petrolatum, ethylene-propylene copolymer, and octadecane amide. The content of such optional additives is, for example, 0.1 to 20.0 mass %, preferably 0.1 to 15.0 mass %, based on the total mass of the composition.

[0016] The grease composition of the present invention can be suitably used for, for example, rolling bearings or gears. Examples of rolling bearings include rolling bearings in steel making equipment continuous casting equipment, rolling bearings in air conditioner fan motors or ventilator fans, and rolling bearings in hub units. Examples of gears include rack and pinion gears in automobiles, worm gears in electric power steering, and worm gears in power window motors.

[0017] Preferred embodiments according to applications will be described in further detail below. (1) First aspect: Grease composition for steel The grease composition for iron and steel continuous casting equipment will be described below. In this specification, the "grease composition for iron and steel continuous casting equipment" may be referred to as the "grease composition for iron and steel." As the base oil, mineral oil is preferred from the viewpoint of economy. Grease compositions for steelmaking are pumped through piping so that they can be used in centralized lubrication facilities, and the kinetic viscosity of the base oil at 40°C is 70 to 600 mm. 2 / s is preferable, and 90 to 500 mm 2 / s is more preferable, 120 to 500 mm 2 / s is more preferred. The content of the base oil in the grease composition for steel making of the present invention is preferably 70 to 97 mass %, more preferably 80 to 95 mass %, and further preferably 85 to 95 mass %, based on the total mass of the composition.

[0018] As the thickener, a diurea compound is preferred from the viewpoint of heat resistance, and an aliphatic urea compound or an aromatic-aliphatic urea compound is preferred from the viewpoint of pumpability. As the aliphatic urea compound, in particular, 1 and R 3 Aliphatic diurea compounds in which both are C8 alkyl are preferred. As the aromatic-aliphatic urea compound, in particular, 1 and R 3 one of which is a C8 alkyl group and the other is a phenyl group; 1 and R 3 An aromatic-aliphatic diurea compound in which the ratio of octyl groups to the total of In the above formula (1), R 1 and R 3 One of the groups is a C8 alkyl group and the other is a para-toluyl group, and R 1 and R 3 An aromatic-aliphatic diurea compound in which the proportion of octyl groups in the total of the above is 40 to 100 mol % is more preferred.

[0019] The consistency of the grease composition for iron and steel of the present invention is preferably 250 to 400, more preferably 265 to 385, and still more preferably 300 to 385, and the content of the thickener is an amount necessary to obtain this consistency. In the grease composition for iron and steel of the present invention, the proportion of the thickener is preferably 2 to 20 mass%, more preferably 2.5 to 15 mass%, and even more preferably 2.5 to 10 mass%. From the viewpoint of water-containing shear stability, the grease composition for steel of the present invention preferably contains rice wax, carnauba wax, lanolin wax or castor wax, and more preferably contains rice wax or carnauba wax. From the viewpoint of water-containing shear stability, the content of these waxes is preferably 0.1 to 5.0 mass %, and more preferably 0.1 to 3.0 mass %, based on the total mass of the grease composition for steel of the present invention. The grease composition for steel of the present invention may also contain, as additives, rust inhibitors, antioxidants, metal corrosion inhibitors, anti-wear agents, extreme pressure agents, solid lubricants, and the like. The content of these optional additives is preferably 0.1 to 20.0 mass %, and more preferably 0.1 to 15.0 mass %, based on the total mass of the grease composition for steel making of the present invention.

[0020] The grease composition for steel of the present invention is particularly The base oil has a kinetic viscosity of 90 to 500 mm at 40°C. 2 / s mineral oil, The thickener is represented by the formula (1), 1 and R 3 an aliphatic diurea compound in which both are C8 alkyl; In the above formula (1), R 1 and R 3 one of which is a C8 alkyl group and the other is a phenyl group; 1 and R 3 An aromatic-aliphatic diurea compound in which the ratio of octyl groups to the total of In the above formula (1), R 1 and R 3 One of the groups is a C8 alkyl group and the other is a para-toluyl group, and R 1 and R 3 an aromatic-aliphatic diurea compound in which the ratio of octyl groups to the total of As additives, the composition may contain 0.1 to 3.0 mass% of rice wax or carnauba wax and 0.01 to 0.5 mass% of a rust inhibitor, based on the total mass of the composition; The consistency is 265 to 385. A grease composition is preferred.

[0021] The grease composition for steel of the present invention is particularly The base oil has a kinetic viscosity of 120 to 500 mm at 40°C. 2 / s mineral oil, The thickener is represented by the formula (1), 1 and R 3 an aliphatic diurea compound in which both are C8 alkyl; In the above formula (1), R 1 and R 3 one of which is a C8 alkyl group and the other is a phenyl group; 1 and R 3 an aromatic-aliphatic diurea compound in which the ratio of octyl groups to the total of As additives, the composition may contain 0.2 to 1.5 mass% of rice wax and 0.1 to 0.5 mass% of a rust inhibitor, based on the total mass of the composition; The consistency is 300 to 385. A grease composition is preferred.

[0022] (2) Second aspect: Grease composition for rolling bearings of fan motors of air conditioners or ventilator fans The grease composition for rolling bearings of fan motors of air conditioners or ventilation fans will be described below. In this specification, the "grease composition for rolling bearings of fan motors of air conditioners or ventilation fans" may also be referred to as the "grease composition for ventilation fans." As the base oil, PAO, ester oil, ether oil or a mixture thereof is preferred from the viewpoints of economy, low temperature properties and low torque properties. Grease compositions for ventilation fans are not used in environments where they are exposed to as much water as rolling bearings for steel, but they are used in environments where they are subject to high humidity and shear stress. In this case, from the viewpoint of low torque and bearing life, the kinetic viscosity of the base oil at 40°C is 30 to 100 mm 2 / s is preferable, 30 to 80 mm 2 / s is more preferred. The content of the base oil in the grease composition for ventilation fans of the present invention is preferably 70 to 93 mass%, more preferably 72 to 90 mass%, and even more preferably 75 to 88 mass%, based on the total mass of the composition. By including the base oil in such a range, it is possible to ensure lubricity at the application location of the grease composition.

[0023] As the thickener, from the viewpoints of low torque and heat resistance, an aliphatic urea compound, an alicyclic-aliphatic diurea compound, or an aromatic-aliphatic urea compound is preferred. As the aliphatic urea compound, in particular, In the above formula (1), R 1 and R 3 and In the above formula (1), R 1 and R 3Aliphatic diurea compounds in which one is a C8 alkyl and the other is a C18 alkyl are preferred. As the alicyclic-aliphatic diurea compounds, in particular In the above formula (1), R 1 and R 3 one of which is a C18 alkyl group and the other is a cyclohexyl group; 1 and R 3 An alicyclic-aliphatic diurea compound in which the proportion of cyclohexyl groups in the total of the above is 25 to 90 mol % is preferred. As the aromatic aliphatic urea compound, in particular, In the above formula (1), R 1 and R 3 One of the groups is a C8 alkyl group and the other is a para-toluyl group, and R 1 and R 3 An aromatic-aliphatic diurea compound in which the proportion of octyl groups in the total of the above is 0 to 40 mol % is preferred.

[0024] The consistency of the grease composition for ventilation fans of the present invention is preferably 180 to 350, more preferably 200 to 300, and the content of the thickener is the amount necessary to obtain this consistency. The proportion of the thickener is preferably 5 to 25 mass%, more preferably 6 to 20 mass%, and even more preferably 8 to 17 mass%. From the viewpoint of water-containing shear stability, the grease composition for ventilation fans of the present invention preferably contains rice wax, carnauba wax, lanolin wax, or castor wax as the wax, and more preferably contains rice wax or carnauba wax. From the viewpoint of water-containing shear stability, the content of these waxes is preferably 0.1 to 5.0 mass %, and more preferably 0.1 to 2.0 mass %, based on the total mass of the grease composition for ventilation fans of the present invention. The grease composition for ventilation fans of the present invention may also contain additives such as rust inhibitors, antioxidants, metal corrosion inhibitors, anti-wear agents, and extreme pressure agents. The content of these optional additives is preferably from 1 to 20 mass %, and more preferably from 2 to 15 mass %, based on the total mass of the grease composition for ventilation fans of the present invention.

[0025] The grease composition for ventilation fans of the present invention is, in particular, The base oil has a kinetic viscosity of 30 to 80 mm at 40°C. 2 / s, PAO, ester oil, ether oil or mixtures thereof; The thickener is represented by the formula (1), 1 and R 3 an aliphatic diurea compound in which both are C8 alkyl; In the above formula (1), R 1 and R 3 an aliphatic diurea compound, wherein one of the groups is a C8 alkyl and the other is a C18 alkyl; In the above formula (1), R 1 and R 3 one of which is a C18 alkyl group and the other is a cyclohexyl group; 1 and R 3 An alicyclic-aliphatic diurea compound in which the ratio of cyclohexyl groups to the total of In the above formula (1), R 1 and R 3 One of the groups is a C8 alkyl group and the other is a para-toluyl group, and R 1 and R 3 an aromatic-aliphatic diurea compound in which the ratio of octyl groups to the total of As additives, the composition may contain 0.1 to 2.0 mass% of rice wax or carnauba wax, 0.1 to 6.0 mass% of an antioxidant, 0.1 to 8.0 mass% of a rust inhibitor, 0.01 to 3.0 mass% of a metal corrosion inhibitor, and 0.1 to 5.0 mass% of an anti-wear agent or an extreme pressure agent, based on the total mass of the composition; The consistency is 200 to 300. A grease composition is preferred.

[0026] (3) Third aspect: Grease composition for rolling bearings of hub units The grease composition for the rolling bearing of a hub unit will be described below. Note that in this specification, the "grease composition for the rolling bearing of a hub unit" may also be referred to as the "grease composition for a hub unit." As the base oil, from the viewpoints of economy and lubricity, a mineral oil, a PAO, an ester oil, or a mixture of two or more of these is preferred, and a mineral oil, a PAO, a mixture of a mineral oil and a PAO, or a mixture of a PAO and an ester oil is more preferred. The kinetic viscosity of the base oil at 40°C is 20 to 300 mm from the viewpoints of wear resistance, peeling resistance, and low torque. 2 / s is preferable, 20 to 200 mm 2 / s is more preferable, 30 to 100 mm 2 / s is more preferred. The content of the base oil in the grease composition for a hub unit of the present invention is preferably 70 to 93 mass %, more preferably 75 to 90 mass %, based on the total mass of the composition. By including the base oil in such a range, it is possible to ensure lubricity at the application location of the grease composition.

[0027] As the thickener, an aliphatic diurea compound or an alicyclic-aliphatic diurea compound is preferred from the viewpoint of heat resistance and acoustic properties. The aliphatic diurea compound is, in the above formula (1), 1 and R 3 Aliphatic diurea compounds in which both are C8 alkyl are preferred. The alicyclic-aliphatic diurea compound is preferably a compound represented by the formula (1): 1 and R 3 one of which is a C18 alkyl group and the other is a cyclohexyl group; 1 and R 3 An alicyclic-aliphatic diurea compound in which the proportion of cyclohexyl groups in the total of the above is 50 to 95 mol % is preferred.

[0028] The consistency of the grease composition for a hub unit of the present invention is preferably 200 to 350, more preferably 230 to 350, and the content of the thickener is the amount necessary to obtain this consistency. The proportion of the thickener is preferably 5 to 25 mass%, more preferably 7 to 15 mass%. From the viewpoint of water-containing shear stability, the grease composition for a hub unit of the present invention preferably contains rice wax, carnauba wax, lanolin wax or castor wax as the wax, and more preferably contains rice wax or carnauba wax. From the viewpoint of water-containing shear stability, the content of these waxes is preferably 0.1 to 5.0 mass %, and more preferably 0.1 to 2.0 mass %, based on the total mass of the grease composition for a hub unit of the present invention. The grease composition for a hub unit of the present invention may also contain additives such as rust inhibitors, antioxidants, metal corrosion inhibitors, anti-wear agents, extreme pressure agents, solid lubricants, and the like. The content of these optional additives is preferably 1.0 to 20 mass %, and more preferably 1.5 to 15 mass %, based on the total mass of the grease composition for a hub unit of the present invention.

[0029] The grease composition for a hub unit of the present invention is, in particular, The base oil has a kinetic viscosity of 20 to 200 mm at 40°C. 2 / s mineral oil, PAO, ester oil, or a mixture of two or more of these, The thickener is represented by the formula (1), 1 and R 3 an aliphatic diurea compound in which both are C8 alkyl, or In the above formula (1), R 1 and R 3 one of which is a C18 alkyl group and the other is a cyclohexyl group; 1 and R 3 and wherein the ratio of cyclohexyl groups to the total of the above is 60 to 90 mol %. As additives, the composition may contain 0.1 to 2.0 mass% of rice wax or carnauba wax, 0.1 to 7.0 mass% of a rust inhibitor, 0.1 to 5.0 mass% of an antioxidant, 0.1 to 4.0 mass% of an anti-wear agent or extreme pressure agent, and 0.5 to 6.0 mass% of a solid lubricant, based on the total mass of the composition; The consistency is 230 to 350. A grease composition is preferred.

[0030] The grease composition for a hub unit of the present invention includes: The base oil has a kinetic viscosity of 30 to 100 mm at 40°C. 2 / s; mineral oil, PAO, a mixture of mineral oil and PAO, or a mixture of PAO and ester oil; The thickener is represented by the formula (1), 1 and R 3 an aliphatic diurea compound in which both are C8 alkyl, or In the above formula (1), R 1 and R 3 one of which is a C18 alkyl group and the other is a cyclohexyl group; 1 and R 3 and wherein the ratio of cyclohexyl groups to the total of the above is 65 to 90 mol %. As additives, the composition may contain 0.1 to 2.0 mass% of rice wax or carnauba wax, 0.1 to 7.0 mass% of a rust inhibitor, 0.1 to 5.0 mass% of an antioxidant, 0.1 to 4.0 mass% of an anti-wear agent or extreme pressure agent, and 0.5 to 6.0 mass% of a solid lubricant, based on the total mass of the composition; The consistency is 230 to 350. Grease compositions are most preferred.

[0031] (4) Fourth aspect: Grease composition for rack and pinion The grease composition for rack and pinion will be described below. As the base oil, mineral oil, PAO, or a mixture thereof is preferred from the viewpoints of economy, lubricity, and low-temperature fluidity. The kinetic viscosity of the base oil at 40°C is 17 to 400 mm from the viewpoint of lubricity and durability. 2 / s is preferable, 17 to 65 mm 2 / s is more preferred. The content of the base oil in the rack and pinion grease composition of the present invention is preferably 70 to 95 mass%, more preferably 70 to 90 mass%, and even more preferably 70 to 85 mass%, based on the total mass of the composition. By including the base oil in such a range, it is possible to ensure lubricity at the application location of the grease composition.

[0032] As the thickener, an aliphatic diurea compound is preferred from the viewpoints of heat resistance and lubricity. The aliphatic diurea compound is, in the above formula (1), 1 and R 3 and In the above formula (1), R 1 and R 3 Aliphatic diurea compounds in which one is a C8 alkyl and the other is a C18 alkyl are more preferred.

[0033] The consistency of the grease composition is preferably 250 to 390, and the content of the thickener is the amount necessary to obtain this consistency. The proportion of the thickener is preferably 3 to 15 mass %. The rack and pinion grease composition of the present invention preferably contains rice wax, carnauba wax, lanolin wax or castor wax as the wax, and more preferably contains rice wax or carnauba wax. The content of these waxes is preferably 0.1 to 5.0 mass %, and more preferably 0.1 to 3.0 mass %, based on the total mass of the grease composition for rack and pinion of the present invention. The rack and pinion grease composition of the present invention may also contain additives such as rust inhibitors, antioxidants, metal corrosion inhibitors, anti-wear agents, extreme pressure agents, solid lubricants, etc. The content of these optional additives is preferably from 0.1 to 20 mass %, and more preferably from 0.5 to 15 mass %, based on the total mass of the grease composition for rack and pinion of the present invention.

[0034] The grease composition for rack and pinion of the present invention includes, among others, The base oil has a kinetic viscosity of 17 to 400 mm at 40°C. 2 / s, preferably 17 to 65 mm 2 / s mineral oil, PAO, or mixtures thereof; The thickener is In the above formula (1), R 1 and R 3 and In the above formula (1), R 1 and R 3 is an aliphatic diurea compound in which one of the alkyl groups is C8 and the other is C18; As additives, based on the total mass of the composition, the composition may contain 0.1 to 3.0 mass% of rice wax or carnauba wax, 0.1 to 5.0 mass% of a rust inhibitor, 0.1 to 1.0 mass% of an antioxidant, 0.01 to 1.0 mass% of a metal corrosion inhibitor, 0.1 to 10 mass% of an anti-wear agent or extreme pressure agent, and 0.1 to 10.0 mass% of a solid lubricant, The consistency is 250 to 390. A grease composition is preferred. EXAMPLES

[0035] <Test grease> In the base oil, 1 mole of diphenylmethane-4,4'-diisocyanate was reacted with 2 moles of aniline and octylamine in total, the temperature was raised to a temperature at which the thickener fiber undergoes a phase transition, and during cooling, wax was added and dissolved in the proportions shown in Tables 1 to 3 to obtain a base grease. Additional base oil was added so that the consistency became 370, and each additive was added in the proportions shown in Tables 1 to 3, and dispersed using a three-roll mill to obtain the grease compositions of the examples and comparative examples. The consistency of the grease composition was adjusted to 370. The respective proportions are shown in Tables 1 to 3. In addition, the numbers in Tables 1 to 3 indicate the molar ratio of aromatic amine (aniline) to aliphatic amine (octylamine) for the thickener, and the rest indicate mass % based on the total mass of the composition. The kinematic viscosity of the base oil at 40° C. was measured in accordance with JIS K2220 23. The consistency of the grease composition was measured in accordance with JIS K2220 7. The grease compositions obtained above were tested and evaluated by the methods described below. The results are shown in Tables 1 to 3.

[0036] <Test Method> - Moisture shell roll test (ASTM D 1831 compliant) This test involves applying shear in a water-contaminated environment, and was used to evaluate water-containing shear stability. [Test conditions] Grease content: 45g - Ion exchange water: 5g Rotational speed: 165 rpm Test temperature: 80℃ Test duration: 24 hours [evaluation] ◎: Difference in consistency before and after the test is 0~30 ○: Difference in consistency before and after the test is 31 to 60 ×: Difference in consistency before and after the test is 61 or more The consistency of grease is classified by grade, and in all of the JIS, ASTM, and NLGI standards, each grade is divided into 45 intervals, with the range of each grade being 30 (±15). The consistency of grease varies depending on the application, but as long as the consistency difference is within 30, it means that the grease can be used for the intended application without any problems.

[0037] [Table 1]

[0038] [Table 2]

[0039] [Table 3]

[0040] The components used to prepare the grease compositions of the Examples and Comparative Examples are as follows: <Base oil> Mineral oil A: Paraffinic mineral oil, kinematic viscosity at 40°C: 130.0 mm 2 / s Mineral oil B: Paraffinic mineral oil, kinematic viscosity at 40°C: 461.2mm 2 / s PAO: Polyalphaolefin, Dynamic viscosity at 40℃: 48.5mm 2 / s Ether oil: alkyl diphenyl ether, kinetic viscosity at 40°C: 68.5mm 2 / s The kinematic viscosity was measured in accordance with JIS K 2220 23. <Wax> Rice wax: Product name: TOWAX-3F17, manufactured by Toa Kasei Co., Ltd. (acid value: 5.4, saponification value: 77.3, iodine value: 7.4) Lanolin wax: Product name: Lanolin wax H, manufactured by Nippon Fine Chemical Co., Ltd. Carnauba wax: Product name: Carnauba No. 2, manufactured by Toa Kasei Co., Ltd. (acid value: 10.0, saponification value: 89.4, iodine value: 8.5) Castor wax: Product name: Castor wax A, manufactured by NOF Corporation Petrolatum: Cas number: 8009-03-8 Ethylene-propylene copolymer: Product name: Licocene PP 3602 GR, manufactured by Clariant Chemicals Co., Ltd. Octadecanamide: Product name: ArmorSlip HT Powder, manufactured by Lion Specialty Chemicals <Rust inhibitor> Dodecenylsuccinic anhydride: Trade name: DSA, manufactured by Sanyo Chemical Industries, Ltd. Alkenyl succinimide: Product name: OLOA 1200, manufactured by Chevron Japan Co., Ltd. Zinc dinonylnaphthalene sulfonate: Product name: NA-SUL ZS, KING INDUSTIES.INC Sodium sebacate: Trade name: IRGACOR DSSG, manufactured by BASF Japan Ltd.

Claims

1. Base oil, Diurea compounds as thickeners, and A grease composition comprising at least one wax selected from the group consisting of rice wax, carnauba wax, lanolin wax, and castor wax.

2. 2. The grease composition according to claim 1, wherein the wax is rice wax or carnauba wax.

3. 2. The grease composition according to claim 1, wherein the wax is rice wax.

4. 2. The grease composition according to claim 1, wherein the diurea compound contains a diurea compound represented by the following formula (1): R 1 -NHGNH-R 2 -NHGNH-R 3 (1) (In the formula, R 2 represents an aromatic hydrocarbon group having 6 to 15 carbon atoms; R 1 and R 3 may be the same or different and represent an aliphatic hydrocarbon group having 8 to 20 carbon atoms or an aromatic hydrocarbon group having 6 to 15 carbon atoms; R 1 and R 3 The proportion of aliphatic hydrocarbon groups in the total of is 40 to 100 mol %.)

5. 2. The grease composition according to claim 1, wherein the diurea compound contains a diurea compound represented by the following formula (1): R 1 -NHGNH-R 2 -NHGNH-R 3 (1) (In the formula, R 2 represents an aromatic hydrocarbon group having 6 to 15 carbon atoms; R 1 and R 3 may be the same or different and are aliphatic hydrocarbon groups having 8 to 20 carbon atoms.

6. The grease composition according to claim 1, further comprising a rust inhibitor.

7. 7. The grease composition according to claim 6, wherein the rust inhibitor comprises at least one of a succinic acid derivative, a metal sulfonate, and an organic acid metal salt.

8. 7. The grease composition according to claim 6, wherein the rust inhibitor is at least one selected from the group consisting of dodecenylsuccinic anhydride, alkenylsuccinimide, zinc dinonylnaphthalenesulfonate, and sodium sebacate.

9. The grease composition according to claim 6, wherein the content of the rust inhibitor is 0.01 to 5 mass % based on the total mass of the composition.

10. The grease composition according to any one of claims 1 to 9, which is for use in rolling bearings or gears.

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