Grease composition

Abstract

A grease composition comprising a base oil, a diurea compound as a thickener, and at least one wax selected from the group consisting of rice bran wax, lanolin wax, carnauba wax, and castor wax.

Description

Technical Field

[0001] This invention relates to a grease composition suitable for use in environments where water can mix or where there is high humidity and shearing is applied. Background Technology

[0002] If water mixes into the grease, it will cause softening and leakage, thus requiring improved water resistance. The grease used in the work roll bearings of hot rolling mills in ironmaking equipment comes into contact with large amounts of cooling water and is subjected to strong shear, therefore requiring excellent water-content shear stability. The grease used in the rolling bearings of fan motors or ventilation fans in air conditioners is used in high-humidity environments and may be subjected to shear, therefore requiring excellent water-content shear stability.

[0003] The grease used in the rolling bearings of automobile wheel hub units can become mixed with water during car washes, rain, and driving on rough roads. It is used in environments that may be subject to shearing, therefore it requires excellent water-containing shear stability.

[0004] In gear applications, especially in automotive racks and pinions, worm gears in electric power steering systems, and worm gears in electric window motors, the greases used are required to have excellent water-containing shear stability because they are used in environments where water may mix in due to weather conditions and they may be subjected to shearing.

[0005] Non-patent literature 1 reports the use of a testing machine (ASTM D1831) to evaluate mechanical shear stability to test a grease consisting only of mineral oil and diurea thickener at 80°C with 10 wt% water content, and the grease became fluid.

[0006] To address the water resistance issue, a method has been reported that, when a diurea compound is selected as the thickener, comprises a metal salt compound selected from basic metal sulfonates, basic metal salicylates, and basic metal phenolates (Patent Document 1). As another method, a method using barium sulfate, a component with excellent water content, as the thickener can be cited (Patent Document 2).

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2002-053884

[0010] Patent Document 2: Japanese Patent Application Publication No. 2016-121336

[0011] Non-patent literature

[0012] Non-patent literature 1: Tribologist, Vol. 35, No. 5 (1990) 343-348 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] Therefore, the objective of this invention is to provide a grease composition with excellent water-containing shear stability.

[0015] Methods for solving problems

[0016] According to the present invention, the following grease composition is provided.

[0017] 1. A grease composition comprising a base oil, a diurea compound as a thickener, and at least one wax selected from rice bran wax, carnauba wax, lanolin wax, and castor wax.

[0018] 2. The grease composition according to 1 above, wherein the wax is rice bran wax or carnauba wax.

[0019] 3. The grease composition according to 1 above, wherein the wax is rice bran wax.

[0020] 4. The grease composition according to any one of 1 to 3 above, wherein the diurea compound contains a diurea compound represented by formula (1) below.

[0021] R 1 -NHCONH-R 2 -NHCONH-R 3 (1)

[0022] In the formula, R 2 R represents an aromatic hydrocarbon group with 6 to 15 carbon atoms. 1 and R 3 They can be the same or different, representing aliphatic hydrocarbon groups with 8-20 carbon atoms or aromatic hydrocarbon groups with 6-15 carbon atoms. Aliphatic hydrocarbon groups are indicated by R. 1 and R 3 The proportion of 40 to 100 moles in the total.

[0023] 5. The grease composition according to any one of 1 to 4 above, wherein the diurea compound contains a diurea compound represented by formula (1) below.

[0024] R 1 -NHCONH-R 2 -NHCONH-R 3 (1)

[0025] In the formula, R 2 R represents an aromatic hydrocarbon group with 6 to 15 carbon atoms. 1 and R 3They can be the same or different, and are aliphatic hydrocarbon groups with 8 to 20 carbon atoms.

[0026] 6. The grease composition according to any one of 1 to 5 above further contains a rust inhibitor.

[0027] 7. The grease composition according to claim 6 above, wherein the rust inhibitor comprises at least one of a succinic acid derivative, a metal sulfonate, and an organic acid metal salt.

[0028] 8. The grease composition according to claim 6 above, wherein the rust inhibitor is at least one selected from the group consisting of dodecenyl succinic anhydride, alkenyl succinimide, zinc dinonylnaphthalene sulfonate, and sodium sebacic acid.

[0029] 9. In the grease composition according to 6 above, the content of rust inhibitor is 0.01 to 5% by mass relative to the total mass of the composition.

[0030] 10. The grease composition according to any one of 1 to 9 above, used in rolling bearings or gears.

[0031] Invention Effects

[0032] The grease composition of the present invention exhibits excellent shear stability when water is incorporated.

[0033] The rationale for believing that this invention can improve aqueous shear stability can be explained in principle as follows: The diurea-based thickener, as a component of the grease, exists in the base oil in the form of fine particles. The capillary force of the network structure formed by these particles holds the base oil in place, forming a semi-solid or solid grease. When the grease is subjected to shear, the network structure of the thickener is disrupted, causing it to soften. In particular, if water is mixed into the aliphatic diurea grease, a significant reduction in oil film thickness and a tendency for shear softening to be promoted are observed. When this is observed at the crystallization level, as described in Non-Patent Document 1, the isocyanate, a raw material for the diurea thickener, reacts with an amine in a stable α-form crystal. During the heating process in the grease manufacturing step, it undergoes a phase transformation to a quasi-stable β-form. When aqueous shear is applied to the diurea grease after the phase transformation, it reverts to the α-form before the phase transformation. Alpha-type grease tends to solidify into lumps, while β-type grease, consisting of thin, elongated fibrous particles, has a greater ability to retain the base oil through capillary forces and is better able to maintain sufficient hardness as a grease. In other words, the reversion of the crystal form to α-type through aqueous shearing signifies softening of the grease.

[0034] Although not bound by any theory, in this invention, it is presumed that at least one wax selected from the group consisting of rice bran wax, carnauba wax, lanolin wax and castor wax plays a role in preventing the diurea thickener from reverting to its pre-phase-transformation molecular arrangement (α-type), resulting in excellent water-content shear stability of the grease composition of this invention. Detailed Implementation

[0035] <Base Oil>

[0036] There are no particular limitations on the types of base oils used in this invention. Examples include mineral oils represented by cycloalkanes and paraffins, synthetic hydrocarbon oils represented by polyalphaolefins (PAO) and polybutene, ether-based synthetic oils represented by alkyl diphenyl ethers and polypropylene glycol, ester-based synthetic oils represented by diesters and polyesters, silicone oils, fluorinated oils, and various other synthetic oils. It should be noted that synthetic oils can be so-called biomass oils manufactured from biological resources produced by plants and animals. For example, biomass ester oils synthesized from various fatty acids and alcohols derived from vegetable oils, and biomass hydrocarbon oils using vegetable oils such as palm oil, corn oil, and soybean oil can also be used. Base oils can be used alone or in mixtures of two or more.

[0037] The base oil of this invention has a kinematic viscosity of, for example, 17 to 600 mm at 40°C. 2 / s.

[0038] Based on the total mass of the composition, the content of base oil in the composition of the present invention is preferably 70-97% by mass, more preferably 80-96% by mass, and even more preferably 85-95% by mass. By containing base oil within such a range, the lubricity of the application area of ​​the grease composition can be ensured.

[0039] Thickener

[0040] The thickener used in this invention is a diurea compound. A diurea compound can be represented by the following formula (1).

[0041] R 1 -NHCONH-R 2 -NHCONH-R 3 (1)

[0042] In the formula, R 2 R represents an aromatic hydrocarbon group with 6 to 15 carbon atoms. 1 and R 3 They can be the same or different, representing aliphatic hydrocarbon groups with 8 to 20 carbon atoms, aromatic hydrocarbon groups with 6 to 15 carbon atoms, or cyclohexyl groups.

[0043] Examples of diurea compounds include:

[0044] -The amine in the raw material is an aromatic-aliphatic urea compound, a mixture of aromatic and aliphatic amines.

[0045] -The amine in the raw material is an aromatic amine, specifically an aromatic urea compound.

[0046] -The amine in the raw material is an aliphatic amine, an aliphatic urea compound.

[0047] -The amine in the raw material is an alicyclic amine, specifically an alicyclic urea compound.

[0048] - The amine in the raw material is an alicyclic-aliphatic urea compound, a mixture of alicyclic and aliphatic amines, or

[0049] - Two or more combinations of them.

[0050] Among them, aromatic-aliphatic urea compounds, aliphatic urea compounds, and alicyclic-aliphatic urea compounds are preferred. It should be noted that when the amines in the raw materials are a mixture, the resulting diurea compounds are also a mixture.

[0051] The diurea compound preferably contains a diurea compound as follows, i.e., in formula (1), R 1 and R 3 They can be the same or different and represent aliphatic hydrocarbon groups with 8 to 20 carbon atoms or aromatic hydrocarbon groups with 6 to 15 carbon atoms. Aliphatic hydrocarbon groups are indicated by R. 1 and R 3 The total proportion of diurea compounds is 40-100 mol%.

[0052] The diurea compound preferably contains a diurea compound as follows, i.e., in formula (1), R 1 and R 3 Diurea compounds can be the same or different and have aliphatic hydrocarbon groups with 8 to 20 carbon atoms.

[0053] The working cone penetration of the grease composition of the present invention is preferably 180 to 400.

[0054] The amount of thickener in the composition of the present invention is only required to adjust the cone penetration to the above-mentioned range, for example, 2.0 to 25% by mass based on the total mass of the composition. It should be noted that in this specification, when referred to simply as "cone penetration", it refers to the 60 working cone penetrations measured according to JIS K22207.

[0055] Wax

[0056] The wax used in this invention is selected from at least one of the group consisting of rice bran wax, carnauba wax, lanolin wax, and castor wax. Rice bran wax or carnauba wax is particularly preferred.

[0057] It should be noted that, in this specification, wax refers to an alkyl-containing organic compound that is solid or semi-solid at room temperature (25°C) and melts within a temperature range of approximately 35°C to 110°C, exhibiting low melt viscosity. Rice bran wax refers to a wax refined from the wax oil separated during the refining of rice bran and rice oil, with CAS number 8016-60-2. Rice bran wax is primarily composed of esters of fatty acids (C16 (approximately 53%), C22 (approximately 20%), C24 (approximately 60%), and the balance being other components) and alcohols. Preferably, the rice bran wax has an acid value of 15 or less and a saponification value of 60-100 or an iodine value of 20.0 or less. That is, partially saponified rice bran wax (CAS number for partially saponified Ca rice bran wax is 1850357-57-1) or hydrogenated rice bran wax can be used. This improves the shear stability when in contact with water. It should be noted that the ratio of the aforementioned fatty acids can be determined by gas chromatography analysis. In addition, acid value can be determined using ISO 2114. Saponification value can be determined using ISO 3681. Iodine value can be determined using the standard oil and fat analysis test method.

[0058] Among them, rice bran wax is preferred, and rice bran wax with an acid value of less than 15 and a saponification value of 60 to 100 or rice bran wax with an acid value of less than 15 and an iodine value of less than 20.0 is particularly preferred.

[0059] Carnauba wax is a refined wax collected from the leaves of the palm coconut plant, with CAS number 8015-86-9. Carnauba wax is primarily composed of esters of fatty acids (C20 (approximately 7%), C22 (approximately 7%), C24 (approximately 25%), C26 (approximately 10%), C28 (approximately 15%), C30 (approximately 4%), C32 (approximately 6%), and the balance being other components) and alcohols. Carnauba wax preferably has an acid value below 12, a saponification value of 70-100, and an iodine value below 4-15. This improves its shear stability when in contact with water. It should be noted that the ratios of the aforementioned fatty acids can be determined by gas chromatography. Furthermore, the acid value can be determined using ISO 2114. The saponification value can be determined using ISO 3681. The iodine value can be determined using the standard oil and fat analysis test method.

[0060] Based on the total mass of the composition, the wax content in the composition of the present invention is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 3.0% by mass, and even more preferably 0.2 to 1.5% by mass. By containing wax in such a range, the water-containing shear stability can be improved.

[0061] <Any additives>

[0062] In addition to the components described above, the grease composition of the present invention may also contain additives commonly used in grease compositions. Examples of such additives include rust inhibitors, antioxidants, metal corrosion inhibitors, wear-resistant agents, extreme pressure agents, and solid lubricants. Rust inhibitors are particularly preferred. Other waxes may also be included, provided they do not impair the effectiveness of the grease composition of the present invention. However, the grease composition of the present invention does not contain lithium soap.

[0063] Rust Inhibitor

[0064] As rust inhibitors that can be used in this invention, alkaline earth metal phenolates or salicylates, some organic acid esters, succinic acid derivatives, or metal sulfonate compounds can be used. They can be used alone or in combination. It should be noted that in this specification, the term "succinic acid derivative" includes unsubstituted succinic acid.

[0065] As a succinic acid derivative, succinic acid, dodecenylsuccinic anhydride or alkenylsuccinimide are preferred, and dodecenylsuccinic anhydride or alkenylsuccinimide are more preferred.

[0066] As a metal sulfonate compound, sulfonates of alkaline earth metals such as zinc sulfonate or calcium sulfonate are preferred. Zinc dinonylnaphthalene sulfonate is more preferred.

[0067] Among them, succinic acid derivatives are preferred, and dodecenylsuccinic anhydride is more preferred.

[0068] Based on the total mass of the composition, the content of the rust inhibitor in the composition of the present invention is preferably 0.01 to 2% by mass, more preferably 0.1 to 1.0% by mass, and even more preferably 0.1 to 0.5% by mass. By containing the rust inhibitor within such a range, rust prevention and water-containing shear stability are improved.

[0069] Examples of antioxidants include amine-based, phenolic-based, quinoline-based, sulfur-based, and zinc dithiophosphate.

[0070] Examples of metal corrosion inhibitors include thiadiazole, benzimidazole, and benzotriazole series.

[0071] Examples of wear-resistant and extreme pressure agents include phosphorus compounds (tricresyl phosphate, tri-2-ethylhexyl phosphate, etc.), sulfur compounds (dibenzyl disulfide, various polysulfides, etc.), sulfur-phosphorus compounds (triphenyl thiophosphate), organometallic extreme pressure agents (Zn, Mo, Sb, Bi salts of dialkyl dithiophosphate, Zn, Mo, Sb, Ni, Cu, Bi salts of dialkyl dithiocarbamate, etc.), and others (ashless dithiocarbamate, ashless dithiophosphate carbamate, etc.).

[0072] Examples of solid lubricants include molybdenum disulfide, graphite, polytetrafluoroethylene, and melamine cyanurate.

[0073] Waxes that are not essential components include petrolatum, ethylene-propylene copolymers, or octadecylamide.

[0074] Based on the total mass of the composition, the content of such an arbitrary additive is, for example, 0.1 to 20.0% by mass, preferably 0.1 to 15.0% by mass.

[0075] The grease composition of the present invention is suitable for applications such as rolling bearings or gears. Examples of rolling bearings include rolling bearings in continuous casting equipment for steel mills, rolling bearings in fan motors or ventilation fans of air conditioners, and rolling bearings in wheel hub units. Examples of gears include racks and pinions in automobiles, worm gears in electric power steering, and worm gears in electric window motors.

[0076] The preferred methods corresponding to the intended use are described in further detail below.

[0077] (1) First method: Steel grease composition

[0078] The following describes the grease composition for continuous casting equipment in steelmaking. It should be noted that in this specification, "grease composition for continuous casting equipment in steelmaking" is sometimes referred to as "grease composition for steelmaking."

[0079] From an economic point of view, mineral oil is preferred as a base oil.

[0080] For use in centralized grease supply systems, the grease composition for steel applications is pressurized via piping; therefore, the kinematic viscosity of the base oil at 40°C is preferably 70-600 mm⁻¹. 2 / s, more preferably 90~500mm 2 / s, more preferably 120~500mm 2 / s.

[0081] Based on the total mass of the composition, the content of base oil in the steel grease composition of the present invention is preferably 70-97% by mass, more preferably 80-95% by mass, and even more preferably 85-95% by mass.

[0082] As a thickener, diurea compounds are preferred from the viewpoint of heat resistance, and aliphatic urea compounds or aromatic-aliphatic urea compounds are preferred from the viewpoint of pressurization.

[0083] As an aliphatic urea compound, R in formula (1) above is particularly preferred. 1 and R 3 All are C8 alkyl aliphatic diurea compounds.

[0084] As an aromatic-aliphatic urea compound, R in formula (1) above is particularly preferred. 1 and R 3 One of them is a C8 alkyl group, the other is a phenyl group, and the octyl group is in the R group. 1 and R 3 The total proportion of aromatic-aliphatic diurea compounds is 40-100 mol%, or R in the above formula (1) is... 1 and R 3 One of them is a C8 alkyl group, the other is p-tolyl, and the octyl group is in the R group. 1 and R 3 The total proportion of aromatic-aliphatic diurea compounds is 40-100 mol%.

[0085] The cone penetration of the steel grease composition of the present invention is preferably 250-400, more preferably 265-385, and even more preferably 300-385. The content of the thickener is the amount required to obtain this cone penetration. In the steel grease composition of the present invention, the proportion of the thickener is preferably 2-20% by mass, more preferably 2.5-15% by mass, and even more preferably 2.5-10% by mass.

[0086] From the viewpoint of water-containing shear stability, the steel grease composition of the present invention preferably contains rice bran wax, carnauba wax, lanolin wax, and castor wax, and more preferably contains rice bran wax or carnauba wax.

[0087] From the viewpoint of water-containing shear stability, the content of these waxes, based on the total mass of the steel grease composition of the present invention, is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 3.0% by mass.

[0088] The grease composition for steel of the present invention may further include rust inhibitors, antioxidants, metal corrosion inhibitors, wear resistant agents, extreme pressure agents, solid lubricants, etc. as additives.

[0089] The content of these arbitrary additives is based on the total mass of the steel grease composition of the present invention, preferably 0.1 to 20.0% by mass, more preferably 0.1 to 15.0% by mass.

[0090] As the steel grease composition of the present invention, the following grease composition is particularly preferred:

[0091] The base oil has a kinematic viscosity of 90~500 mm at 40°C. 2 / s of mineral oil,

[0092] The thickener is R in formula (1) above. 1 and R 3All are C8 alkyl aliphatic diurea compounds.

[0093] R in the above formula (1) 1 and R 3 One of them is a C8 alkyl group, the other is a phenyl group, and the octyl group is in the R group. 1 and R 3 The total proportion of aromatic-aliphatic diurea compounds is 40-100 mol%, or

[0094] R in the above formula (1) 1 and R 3 One of them is a C8 alkyl group, the other is p-tolyl, and the octyl group is in the R group. 1 and R 3 The total proportion of aromatic-aliphatic diurea compounds is 40-100 mol% in the total.

[0095] As an additive, based on the total mass of the composition, it may contain 0.1 to 3.0% by mass of rice bran wax or carnauba wax, and 0.01 to 0.5% by mass of rust inhibitor.

[0096] Furthermore, the cone penetration is 265~385.

[0097] As the steel grease composition of the present invention, the following grease composition is particularly preferred:

[0098] The base oil has a kinematic viscosity of 120~500 mm at 40°C. 2 / s of mineral oil,

[0099] The thickener is R in formula (1) above. 1 and R 3 All are C8 alkyl aliphatic diurea compounds.

[0100] R in the above formula (1) 1 and R 3 One of them is a C8 alkyl group, the other is a phenyl group, and the octyl group is in the R group. 1 and R 3 The total proportion of aromatic-aliphatic diurea compounds is 70-90 mol% in the total.

[0101] As an additive, based on the total mass of the composition, it may contain 0.2 to 1.5% by mass of rice bran wax and 0.1 to 0.5% by mass of rust inhibitor.

[0102] Furthermore, the cone penetration is 300~385.

[0103] (2) Second method: a grease composition for the rolling bearings of the air conditioner's fan motor or exhaust fan.

[0104] The following describes a grease composition for the rolling bearings of an air conditioner fan motor or exhaust fan. It should be noted that in this specification, "grease composition for the rolling bearings of an air conditioner fan motor or exhaust fan" is sometimes referred to as "grease composition for an exhaust fan".

[0105] From the viewpoints of economy, low temperature and low torque, PAO, ester oil, ether oil or mixtures thereof are preferred as base oils.

[0106] Unlike rolling bearings for steel, which are used in environments exposed to large amounts of water, grease compositions for ventilation fans are suitable for use in high-humidity environments where shear stress is possible. In such cases, from the viewpoint of low torque and bearing life, the kinematic viscosity of the base oil at 40°C is preferably 30–100 mm⁻¹. 2 / s, more preferably 30~80mm 2 / s.

[0107] Based on the total mass of the composition, the base oil content in the grease composition for ventilation fans of the present invention is preferably 70-93% by mass, more preferably 72-90% by mass, and even more preferably 75-88% by mass. By containing base oil within this range, the lubricity of the application area of ​​the grease composition can be ensured.

[0108] From the viewpoint of low torque and heat resistance, aliphatic urea compounds, alicyclic-aliphatic diurea compounds, or aromatic-aliphatic urea compounds are preferred as thickeners.

[0109] As an aliphatic urea compound, R in formula (1) above is particularly preferred. 1 and R 3 All are C8 alkyl aliphatic diurea compounds, or R in formula (1) above. 1 and R 3 One of them is an aliphatic diurea compound with a C8 alkyl group and the other is a C18 alkyl group.

[0110] As an alicyclic-aliphatic diurea compound, R in the above formula (1) is particularly preferred. 1 and R 3 One of them is a C18 alkyl group, and the other is a cyclohexyl group, wherein the cyclohexyl group is in the R group. 1 and R 3 The total proportion of alicyclic-aliphatic diurea compounds is 25-90 mol%.

[0111] As an aromatic aliphatic urea compound, R in the above formula (1) is particularly preferred. 1 and R 3 One of them is a C8 alkyl group, the other is p-tolyl, and the octyl group is in the R group. 1 and R3 The total proportion of aromatic-aliphatic diurea compounds is 0-40 mol%.

[0112] The cone penetration 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 required to obtain this cone penetration. The proportion of the thickener is preferably 5 to 25% by mass, more preferably 6 to 20% by mass, and even more preferably 8 to 17% by mass.

[0113] From the viewpoint of water-containing shear stability, the grease composition for ventilation fans of the present invention preferably contains rice bran wax, carnauba wax, lanolin wax, and castor wax as wax, and more preferably contains rice bran wax or carnauba wax.

[0114] From the viewpoint of water-containing shear stability, the content of these waxes, based on the total mass of the grease composition for ventilation fans of the present invention, is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 2.0% by mass.

[0115] The grease composition for ventilation fans of the present invention may also contain rust inhibitors, antioxidants, metal corrosion inhibitors, wear-resistant agents, extreme pressure agents, etc. as additives.

[0116] The content of these arbitrary additives is preferably 1 to 20% by mass, more preferably 2 to 15% by mass, relative to the total mass of the grease composition for ventilation fans of the present invention.

[0117] The grease composition for the ventilation fan of the present invention is particularly preferred as the following grease composition:

[0118] The base oil has a kinematic viscosity of 30~80 mmHg at 40°C. 2 / s of PAO, ester oil, ether oil, or mixtures thereof

[0119] The thickener is R in formula (1) above. 1 and R 3 All are C8 alkyl aliphatic diurea compounds.

[0120] R in the above formula (1) 1 and R 3 One of them is an aliphatic diurea compound with a C8 alkyl group and the other is a C18 alkyl group.

[0121] R in the above formula (1) 1 and R 3 One of them is a C18 alkyl group, and the other is a cyclohexyl group, wherein the cyclohexyl group is in the R group. 1 and R 3 The total proportion of alicyclic-aliphatic diurea compounds is 25-90 mol%, or

[0122] R in the above formula (1) 1 and R 3 One of them is a C8 alkyl group, the other is p-tolyl, and the octyl group is in the R group. 1 and R 3 Aromatic-aliphatic diurea compounds constitute 0-30 mol% of the total.

[0123] As an additive, based on the total mass of the composition, it may contain 0.1 to 2.0% by mass of rice bran wax or carnauba wax, 0.1 to 6.0% by mass of antioxidant, 0.1 to 8.0% by mass of rust inhibitor, 0.01 to 3.0% by mass of metal corrosion inhibitor, 0.1 to 5.0% by mass of wear-resistant agent, and extreme pressure agent.

[0124] Furthermore, the cone penetration is 200~300.

[0125] (3) Third method: grease composition for rolling bearings of hub unit

[0126] The following describes the grease composition for the rolling bearings of the hub unit. It should be noted that in this specification, "grease composition for the rolling bearings of the hub unit" is sometimes referred to as "grease composition for the hub unit".

[0127] From the viewpoint of economy and lubrication, mineral oil, PAO, ester oil, or a mixture of two or more thereof are preferred as base oils, and mineral oil, PAO, a mixture of mineral oil and PAO, or a mixture of PAO and ester oil are more preferred.

[0128] From the perspectives of wear resistance, peel resistance, and low torque, the kinematic viscosity of the base oil at 40°C is preferably 20~300 mmHg. 2 / s, more preferably 20~200mm 2 / s, further preferably 30~100mm 2 / s.

[0129] Based on the total mass of the composition, the base oil content in the wheel hub unit grease composition of the present invention is preferably 70-93% by mass, more preferably 75-90% by mass. By containing base oil within this range, the lubricity of the application area of ​​the grease composition can be ensured.

[0130] As a thickener, from the viewpoint of heat resistance and acoustic properties, aliphatic diurea compounds or alicyclic-aliphatic diurea compounds are preferred.

[0131] As an aliphatic diurea compound, R in the above formula (1) is preferred. 1 and R 3All are C8 alkyl aliphatic diurea compounds.

[0132] As an alicyclic-aliphatic diurea compound, R in formula (1) above is preferred. 1 and R 3 One of them is a C18 alkyl group, and the other is a cyclohexyl group, wherein the cyclohexyl group is in the R group. 1 and R 3 The total proportion of alicyclic-aliphatic diurea compounds is 50-95 mol%.

[0133] The cone penetration of the grease composition for wheel hub units of the present invention is preferably 200-350, more preferably 230-350, and the content of the thickener is the amount required to obtain this cone penetration. The proportion of the thickener is preferably 5-25% by mass, more preferably 7-15% by mass.

[0134] From the viewpoint of water-containing shear stability, the grease composition for wheel hub units of the present invention preferably contains rice bran wax, carnauba wax, lanolin wax, and castor wax as wax, and more preferably contains rice bran wax or carnauba wax.

[0135] From the viewpoint of water-containing shear stability, the content of these waxes is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 2.0% by mass, based on the total mass of the grease composition for wheel hub units of the present invention.

[0136] The grease composition for wheel hub units of the present invention may also contain rust inhibitors, antioxidants, metal corrosion inhibitors, wear resistant agents, extreme pressure agents, solid lubricants, etc. as additives.

[0137] Based on the total mass of the grease composition for wheel hub units of the present invention, the content of these arbitrary additives is preferably 1.0 to 20% by mass, more preferably 1.5 to 15% by mass.

[0138] The grease composition for the hub unit of the present invention is particularly preferred as the following grease composition:

[0139] The base oil has a kinematic viscosity of 20~200 mmHg at 40°C. 2 / s of mineral oil, PAO, ester oil, or a mixture of two or more of them.

[0140] The thickener is R in formula (1) above. 1 and R 3 All are C8 alkyl aliphatic diurea compounds, or

[0141] In the above formula (1), R 1 and R 3 One of them is a C18 alkyl group, and the other is a cyclohexyl group, wherein the cyclohexyl group is in the R group. 1 and R3 The total proportion of alicyclic-aliphatic diurea compounds is 60-90 mol% in the total.

[0142] As an additive, based on the total mass of the composition, it may contain 0.1 to 2.0% by mass of rice bran wax or carnauba wax, 0.1 to 7.0% by mass of rust inhibitor, 0.1 to 5.0% by mass of antioxidant, 0.1 to 4.0% by mass of wear-resistant agent, extreme pressure agent, and 0.5 to 6.0% by mass of solid lubricant.

[0143] Furthermore, the cone penetration is 230~350.

[0144] The most preferred grease composition for the wheel hub unit of the present invention is as follows:

[0145] The base oil has a kinematic viscosity of 30~100 mm at 40°C. 2 / s of mineral oil, PAO, mixtures of mineral oil and PAO, or mixtures of PAO and ester oil.

[0146] The thickener is R in formula (1) above. 1 and R 3 All are C8 alkyl aliphatic diurea compounds or R in formula (1) above. 1 and R 3 One of them is a C18 alkyl group, and the other is a cyclohexyl group, wherein the cyclohexyl group is in the R group. 1 and R 3 The total proportion of alicyclic-aliphatic diurea compounds is 65-90 mol% in the total.

[0147] As an additive, based on the total mass of the composition, it may contain 0.1 to 2.0% by mass of rice bran wax or carnauba wax, 0.1 to 7.0% by mass of rust inhibitor, 0.1 to 5.0% by mass of antioxidant, 0.1 to 4.0% by mass of wear-resistant agent, extreme pressure agent, and 0.5 to 6.0% by mass of solid lubricant.

[0148] Furthermore, the cone penetration is 230~350.

[0149] (4) Fourth method: Grease composition for racks and pinions

[0150] The following describes the grease composition for racks and pinions.

[0151] From the perspectives of economy, lubrication, and low-temperature fluidity, mineral oil, PAO, or mixtures thereof are preferred as base oils.

[0152] From the perspective of lubrication and durability, the kinematic viscosity of the base oil at 40°C is preferably 17~400 mmHg.2 / s, more preferably 17~65mm 2 / s.

[0153] Based on the total mass of the composition, the base oil content in the rack and pinion grease composition of the present invention is preferably 70-95% by mass, more preferably 70-90% by mass, and even more preferably 70-85% by mass. By containing base oil within this range, the lubricity of the application area of ​​the grease composition can be ensured.

[0154] From the viewpoint of heat resistance and lubrication, aliphatic diurea compounds are preferred as thickeners.

[0155] As an aliphatic diurea compound, R in the above formula (1) is more preferred. 1 and R 3 All are C8 alkyl aliphatic diurea compounds, or R in formula (1) above 1 and R 3 One of them is an aliphatic diurea compound with a C8 alkyl group and the other is a C18 alkyl group.

[0156] The cone penetration of the grease composition is preferably 250 to 390, and the amount of thickener is the amount required to obtain this cone penetration. The proportion of thickener is preferably 3 to 15% by mass.

[0157] The grease composition for racks and pinions of the present invention preferably contains rice bran wax, carnauba wax, lanolin wax, and castor wax as wax, and more preferably contains rice bran wax or carnauba wax.

[0158] Based on the total mass of the grease composition for racks and pinions of the present invention, the content of these waxes is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 3.0% by mass.

[0159] The grease composition for racks and pinions of the present invention may also contain rust inhibitors, antioxidants, metal corrosion inhibitors, wear resistant agents, extreme pressure agents, solid lubricants, etc. as additives.

[0160] Based on the total mass of the grease composition for racks and pinions of the present invention, the content of these arbitrary additives is preferably 0.1 to 20% by mass, more preferably 0.5 to 15% by mass.

[0161] As the grease composition for racks and pinions of the present invention, the following grease composition is particularly preferred:

[0162] The base oil has a kinematic viscosity of 17~400 mm at 40°C. 2 / s, preferably 17~65mm 2 / s of mineral oil, PAO, or mixtures thereof

[0163] The thickener is R in formula (1) above. 1 and R 3 All are C8 alkyl aliphatic diurea compounds, or R in formula (1) above 1 and R 3 One of them is an aliphatic diurea compound with a C8 alkyl group and the other is a C18 alkyl group.

[0164] As an additive, based on the total mass of the composition, it may contain 0.1 to 3.0% by mass of rice bran wax or carnauba wax, 0.1 to 5.0% by mass of rust inhibitor, 0.1 to 1.0% by mass of antioxidant, 0.01 to 1.0% by mass of metal corrosion inhibitor, 0.1 to 10% by mass of wear-resistant agent, extreme pressure agent, and 0.1 to 10.0% by mass of solid lubricant.

[0165] Furthermore, the cone penetration is 250~390.

[0166] [Example]

[0167] Test Grease

[0168] In the base oil, 2 moles of aniline and octylamine were reacted relative to 1 mole of diphenylmethane-4,4'-diisocyanate. The mixture was heated to the temperature at which the thickener fibers undergo a phase transition. During cooling, wax was added according to the formulations shown in Tables 1-3 to dissolve the mixture and obtain the base grease. Additional base oil was added with a cone penetration of 370°, and each additive was added in the proportions shown in Tables 1-3. The mixture was dispersed using a three-roll mill to obtain the grease compositions of the examples and comparative examples. The cone penetration of the grease compositions was adjusted to 370°. The respective formulations are shown in Tables 1-3.

[0169] It should be noted that, regarding the figures in Tables 1 to 3, the "ratio" of thickeners indicates the molar ratio of aromatic amines (aniline) to aliphatic amines (octylamine), and otherwise indicates the mass based on the total mass of the composition.

[0170] It should be noted that the kinematic viscosity of the base oil at 40°C was determined according to JIS K2220 23. The cone penetration of the grease composition was determined according to JIS K2220 7.

[0171] The grease compositions obtained above were tested and evaluated using the methods shown below. The results are shown in Tables 1 to 3.

[0172] Test Methods

[0173] 〇 Shell roll test (according to ASTM D 1831)

[0174] This test applies shear stress in an environment containing moisture. The purpose of this test is to evaluate the water-bearing shear stability.

[0175] [Experimental Conditions]

[0176] • Grease filling amount: 45g

[0177] • Ion-exchanged water: 5g

[0178] • Speed: 165 rpm

[0179] • Test temperature: 80℃

[0180] • Test duration: 24 hours

[0181] [evaluate]

[0182] ◎: The difference in cone penetration before and after the test is 0~30.

[0183] ○: The difference in cone penetration before and after the test was 31~60.

[0184] ×: The difference in cone penetration before and after the test is 61 or more.

[0185] It should be noted that the cone penetration of greases is classified by grade. JIS, ASTM, and NLGI all use a 45-degree range for Grade 1, which is 30 (±15). The cone penetration of greases varies depending on the application. If the cone penetration difference is within 30 degrees, it means that it can be used for the target application without problems.

[0186] [Table 1]

[0187]

[0188] [Table 2]

[0189]

[0190] [Table 3]

[0191]

[0192] The components used to prepare the grease compositions of the examples and comparative examples are as follows.

[0193] <Base Oil>

[0194] • Mineral Oil A: Paraffinic mineral oil, kinematic viscosity at 40°C: 130.0 mm 2 / s

[0195] • Mineral Oil B: Paraffinic mineral oil, kinematic viscosity at 40°C: 461.2 mmHg 2 / s

[0196] • PAO: Polyalphaolefin, kinematic viscosity at 40°C: 48.5 mm 2 / s

[0197] • Ether oil: Alkyl diphenyl ether, kinematic viscosity at 40°C: 68.5 mm 2 / s

[0198] It should be noted that kinematic viscosity was determined according to JIS K2220 23.

[0199] Wax

[0200] • Rice bran wax: Trade name: TOWAX-3F17, manufactured by Toa Chemical Co., Ltd. (Acid value: 5.4, Saponification value: 77.3, Iodine value: 7.4)

[0201] • Lanolin wax: Trade name: LANOLIN WAX H, manufactured by Nippon Seika Co., Ltd.

[0202] • Carnauba wax: Trade name: CARNAUBA No. 2, manufactured by Toa Chemical Co., Ltd. (Acid value: 10.0, Saponification value: 89.4, Iodine value: 8.5)

[0203] • Castor wax: Trade name: CASTOR WAX A, manufactured by Nippon Yu Co., Ltd.

[0204] • Vaseline: CAS No.: 8009-03-8

[0205] • Ethylene-propylene copolymer: Trade name: Licocene PP 3602 GR, manufactured by Clariant Chemicals Co., Ltd.

[0206] • Octadecanamide: Trade name: ARMOSLIP HT POWDER, manufactured by Lion Specialty Chemicals.

[0207] Rust Inhibitor

[0208] • Dodecenylsuccinic anhydride: Trade name: DSA, manufactured by Sanyo Chemical Industries, Ltd.

[0209] • Alkenyl succinimide: Trade name: OLOA 1200, manufactured by Chevron Japan Co., Ltd.

[0210] • Zinc dinonylnaphthalenesulfonate: Trade names: NA-SUL ZS, KING INDUSTIES.INC

[0211] • Sodium sebacate: Trade name: IRGACOR DSSG, manufactured by BASF JAPAN Co., Ltd.

Claims

1. A grease composition comprising: base oil, diurea compounds as thickeners, and Choose at least one wax from the group consisting of rice bran wax, carnauba wax, lanolin wax, and castor wax.

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

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

4. The grease composition according to claim 1, wherein, Diurea compounds contain diurea compounds represented by the following formula (1), R 1 -NHCONH-R 2 -NHCONH-R 3 (1) In the formula, R 2 R represents an aromatic hydrocarbon group with 6 to 15 carbon atoms. 1 and R 3 They can be the same or different, representing aliphatic hydrocarbon groups with 8-20 carbon atoms or aromatic hydrocarbon groups with 6-15 carbon atoms. Aliphatic hydrocarbon groups are indicated by R. 1 and R 3 The proportion of 40 to 100 moles in the total.

5. The lubricating grease composition according to claim 1, wherein, Diurea compounds contain diurea compounds represented by the following formula (1), R 1 -NHCONH-R 2 -NHCONH-R 3 (1) In the formula, R 2 R represents an aromatic hydrocarbon group with 6 to 15 carbon atoms. 1 and R 3 They can be the same or different, and are aliphatic hydrocarbon groups with 8 to 20 carbon atoms.

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

7. The grease composition according to claim 6, wherein, Rust inhibitors contain at least one of succinic acid derivatives, metal sulfonates, and organic acid metal salts.

8. 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% of the total mass of the composition.

10. The grease composition according to any one of claims 1 to 9, used in rolling bearings or gears.

Images