Grease composition

Abstract

The present invention contains a base oil (A) and a thickener (B). The thickener (B) is one or more selected from lithium soap (B2) and one or more urea-based thickener agents (B1) selected from diurea compounds represented by general formula (b1). General formula (b1): R1-NHCONH-R3-NHCONH-R2 [In general formula (b1), R1 and R2 each independently represent a C6-24 monovalent chain hydrocarbon group or an alicyclic hydrocarbon group, R1 and R2 may be the same as or different from each other, and R3 represents a 6-18 C divalent aromatic hydrocarbon group.] In R1 and R2 in general formula (b1), when the chain hydrocarbon group content is set to be X molar equivalents and the alicyclic hydrocarbon group content is set to be Y molar equivalents, requirement (1) is satisfied. ・Requirement (1): The ratio X / Y is 3 / 2 or greater. Provided is a grease composition in which the Young's modulus of the thickener (B) is 1.4 GPa or less, and which has excellent torque reduction properties due to approach from the thickener.

Description

Grease composition

[0001] This invention relates to a grease composition.

[0002] The hub bearings (hub unit bearings) mounted on the wheels of automobiles are components that support the wheels and allow them to rotate smoothly. Because these hub unit bearings are constantly rotating components, fluid lubricating oil compositions cannot be used; therefore, semi-solid grease compositions are employed as lubricants. To reduce the viscous resistance of the grease composition and suppress energy loss, it is desirable to lower the rotational torque.

[0003] For example, Patent Document 1 discloses a grease composition that is sealed in a wheel bearing and satisfies the problem of low torque performance, and contains a base oil consisting of mineral oil and synthetic hydrocarbon oil, and a thickener containing a urea compound.

[0004] Japanese Patent Publication No. 2015-172153

[0005] In the technology described in Patent Document 1, the kinematic viscosity of the base oil (mixed oil) contained in the grease composition at 40°C is set to 40 mm². ２ / s ~ 65mm ２ By lowering the torque by / s, the torque is reduced. However, the approach of reducing torque through thickeners has not been sufficiently investigated.

[0006] Therefore, the object of the present invention is to provide a grease composition with excellent torque reduction properties through an approach using a thickener.

[0007] The present invention provides the following [1] to [3]: [1] A base oil (A) and a thickener (B), wherein the thickener (B) is one or more urea-based thickeners (B1) selected from diurea compounds represented by the following general formula (b1), and one or more lithium soaps (B2), R １ -NHCONH-R ３ -NHCONH-R ２ (b1) [In the above general formula (b1), R １ and R ２each independently represent a monovalent chain hydrocarbon group or alicyclic hydrocarbon group having 6 to 24 carbon atoms. R １ and R ２ may be the same as or different from each other. R ３ represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms.] When the content of the chain hydrocarbon group in R １ and R ２ of the general formula (b1) is X molar equivalent, and the content of the alicyclic hydrocarbon group is Y molar equivalent, the following requirement (1) is satisfied: Requirement (1): the X / Y ratio is 3 / 2 or more. A grease composition wherein the Young's modulus of the thickener (B) is 1.4 GPa or less. [2] A regulation method for adjusting the Young's modulus of the thickener (B) to 1.4 GPa or less by selecting one or more urea-based thickeners (B1) selected from diurea compounds represented by the following general formula (b1) and / or one or more thickeners (B) selected from lithium soap (B2). R １ -NHCONH-R ３ -NHCONH-R ２ (b1) [In the above general formula (b1), R １ and R ２ each independently represent a monovalent chain hydrocarbon group or alicyclic hydrocarbon group having 6 to 24 carbon atoms. R １ and R ２ may be the same as or different from each other. R ３ represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms.] When the content of the chain hydrocarbon group in R １ and R ２ of the general formula (b1) is X molar equivalent, and the content of the alicyclic hydrocarbon group is Y molar equivalent, the following requirement (1) is satisfied: Requirement (1): the X / Y ratio is 3 / 2 or more. [3] A method for producing a grease composition, comprising a step of carrying out the preparation method according to [2] above.

[0008] According to the present invention, it is possible to provide a grease composition excellent in torque reduction performance through an approach from the thickener.

[0009] The upper and lower limits of the numerical ranges described herein can be combined in any way. For example, if the numerical ranges "A to B" and "C to D" are described, the numerical ranges "A to D" and "C to B" are also included within the scope of the present invention. Furthermore, unless otherwise specified, the numerical ranges "lower limit to upper limit" described herein mean greater than or equal to the lower limit and less than or equal to the upper limit.

[0010] [Description of Grease Composition] The grease composition of this embodiment is a grease composition containing a base oil (A) and a thickener (B), wherein the thickener (B) is one or more urea-based thickeners (B1) selected from diurea compounds represented by the following general formula (b1), and one or more lithium soaps (B2), R １ -NHCONH-R ３ -NHCONH-R ２ (b1) [In the above general formula (b1), R １ and R ２ Each of these independently represents a monovalent chain hydrocarbon group or alicyclic hydrocarbon group having 6 to 24 carbon atoms. １ and R ２ They may be the same or they may be different from one another. ３ R represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ] In the above general formula (b1) R １ and R ２ In this grease composition, when the content of chain hydrocarbon groups is X molar equivalents and the content of alicyclic hydrocarbon groups is Y molar equivalents, the following requirement (1) is met: Requirement (1): The X / Y ratio is 3 / 2 or more. The Young's modulus of the thickener (B) is 1.4 GPa or less.

[0011] The inventors diligently conducted research to solve the above problems. As a result, they discovered that the above problems could be solved by creating a grease composition in which the Young's modulus of the thickener contained in the grease composition is within a specific range, and thus completed the present invention.

[0012] In the following explanation, "base oil (A)" and "thickener (B)" will also be referred to as "component (A)" and "component (B)," respectively.

[0013] In the grease composition of this embodiment, the total content of component (A) and component (B) is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the total amount (100% by mass) of the grease composition. Also, it is usually 100% by mass or less, preferably less than 100% by mass, more preferably 99% by mass or less, and even more preferably 98% by mass or less. The grease composition of this embodiment may contain other components other than component (A) and component (B) as long as they do not impair the effects of the present invention.

[0014] The components included in the grease composition of this embodiment will be described in detail below.

[0015] <Base oil (A)> The grease composition of this embodiment contains base oil (A).

[0016] The base oil (A) preferably contains poly-α-olefin (hereinafter also referred to as "PAO") (A1). By including PAO (A1) in the base oil (A), the evaporability of the mixed base oil can be reduced. Examples of PAO (A1) include polybutene, polyisobutylene, 1-decene oligomer, and ethylene-propylene copolymer, as well as their hydrogenated products. PAO (A1) may be used alone or in combination of two or more types.

[0017] PAO (A1) preferably contains one or more selected from the group consisting of low viscosity low evaporative PAO (A1-1), medium viscosity PAO (A1-2), and high viscosity PAO (A1-3). These may be used individually or in combination of two or more.

[0018] <<Low viscosity, low evaporation PAO (A1-1)>> As for PAO (A1), １３It is preferable to include low-viscosity, low-evaporation PAO (A1-1) in which the ratio of methyl groups on tertiary carbons bonded to secondary and tertiary carbons is 10.0% or more, as determined from the C-NMR spectrum by the following formula (1). By including low-viscosity, low-evaporation PAO (A1-1) in PAO (A1), evaporation can be reduced, thereby extending the life of the grease composition. Ratio of methyl groups on tertiary carbons bonded to secondary and tertiary carbons = α / (α + β + γ + δ) × 100 ... (1) α: integral value of 15.1 to 16.1 ppm β: integral value of 13.7 to 14.7 ppm γ: integral value of 19.6 to 20.6 ppm δ: integral value of 26.3 to 27.3 ppm

[0019] In low-viscosity, low-evaporation PAO (A1-1), it is preferable that the ratio of methyl groups on tertiary carbons having bonds with secondary and tertiary carbons, as determined by the above formula (1), is 10.0% or more. When the ratio of methyl groups is 10.0% or more, it exhibits excellent torque reduction properties. The ratio of methyl groups is preferably 10.0 to 50.0%, more preferably 11.0 to 30.0%, even more preferably 12.0 to 25.0%, and even more preferably 12.0 to 20.0%.

[0020] Poly-α-olefins are usually obtained as a mixture of multiple structural isomers resulting from their polymerization process. For example, a trimer is a mixture of structural isomers represented by the following formulas (a), (b), and (c).

[0021] (In the formula, L represents a divalent saturated aliphatic hydrocarbon group.)

[0022] The low-viscosity, low-evaporation PAO (A1-1) used in this embodiment preferably contains a large amount of the structural isomer represented by formula (a) above. In this embodiment, the ratio of the structural isomer represented by formula (a) is １３To identify the compound using C-NMR, the above formula (1) is used. Here, the integral values ​​of α, β, γ, and δ defined in formula (1) each originate from a specific methyl group, and their correspondence is shown in formulas (a), (b), and (c). More specifically, the integral value (α) from 15.1 to 16.1 ppm originates from the methyl group indicated as α in formula (a), the integral value (β) from 13.7 to 14.7 ppm originates from the methyl group indicated as β in formulas (a), (b), and (c), as well as other isomers and tetramers or more, the integral value (γ) from 19.6 to 20.6 ppm originates from the methyl group indicated as γ in formula (b), and the integral value (δ) from 26.3 to 27.3 ppm originates from the methyl group indicated as δ in formula (c). Thus, poly-α-olefins having a ratio of 10.0% or more of methyl groups as defined by formula (1) contain a relatively large amount of the structural isomer shown in formula (a). Grease compositions obtained by using poly-α-olefins containing a relatively large amount of the structural isomer shown in formula (a) as a base oil have low evaporability and excellent torque reduction properties because the molecular weight can be increased despite the low kinematic viscosity of the base oil.

[0023] The method for producing poly-α-olefins in which the ratio of methyl groups specified by formula (1) above is 10.0% or more is not particularly limited, but for example, it can be obtained by synthesizing using α-olefin as a raw material and sequentially using a metallocene catalyst and an acid catalyst. More specifically, by synthesizing a dimer using a metallocene catalyst and then a trimer using poly-α-olefin as a raw material, the movement of methyl groups can be selectively induced only in the reaction using the acid catalyst, so that poly-α-olefins with a high ratio of methyl groups specified by formula (1) above can be efficiently synthesized. In addition, the ratio of methyl groups specified by formula (1) above can be adjusted by mixing multiple poly-α-olefins.

[0024] Examples of low-viscosity, low-evaporation PAO (A1-1) include polybutene, polyisobutylene, 1-decene oligomer, and ethylene-propylene copolymer, as well as their hydrides. These may be used individually or in combination of two or more. The low-viscosity, low-evaporation PAO (A1-1) is preferably a 1-decene oligomer, and particularly preferably a trimer of 1-decene.

[0025] In the grease composition of this embodiment, the kinematic viscosity at 40°C of the low-viscosity, low-evaporation PAO (A1-1) is preferably 2 mm². ２ / s or more 50mm ２ / s or less, more preferably 5 mm ２ / s or more 40mm ２ / s or less, more preferably 8 mm ２ / s or more 30mm ２ / s or less, more preferably 10 mm ２ / s or more 25mm ２ It is less than / s. The kinematic viscosity at 40°C for low viscosity, low evaporation PAO (A1-1) is 2 mm². ２ If the kinematic viscosity is 50 mmHg or higher, it exhibits excellent resistance to evaporation. The kinematic viscosity of low-viscosity, low-evaporation PAO (A1-1) at 40°C is 50 mmHg. ２ When the coefficient of flux is less than or equal to / s, the torque reduction performance is excellent. In the grease composition of this embodiment, the viscosity index of the low viscosity low evaporation PAO (A1-1) is preferably 100 or higher, more preferably 110 or higher, and even more preferably 120 or higher. When the viscosity index of the low viscosity low evaporation PAO (A1-1) is 100 or higher, the effects of the present invention are more easily improved.

[0026] In the grease composition of this embodiment, the content of low viscosity low evaporative PAO (A1-1) in the base oil (A) is preferably 25% by mass or more and 90% by mass or less, more preferably 35% by mass or more and 80% by mass or less, even more preferably 40% by mass or more and 70% by mass or less, and even more preferably 50% by mass or more and 60% by mass or less, based on the total amount of base oil (A), from the viewpoint of reducing the evaporative properties of the mixed base oil.

[0027] <<Medium Viscosity PAO (A1-2)>> As for the medium viscosity PAO (A1-2), any PAO with a kinematic viscosity at 40°C within a predetermined range can be used without particular limitations. In the grease composition of this embodiment, the kinematic viscosity at 40°C of the medium viscosity PAO (A1-2) is preferably 10 mm². ２ / s or more 60mm ２ / s or less, more preferably 15 mm ２ / s or more 50mm ２ / s or less, more preferably 20 mm ２ / s or more 40mm ２ / s or less, more preferably 25 mm ２ / s or more 35mm ２ It is less than / s. The kinematic viscosity at 40°C for medium viscosity PAO (A1-2) is 10 mm². ２ If the kinematic viscosity is 60 mmHg or higher, it exhibits excellent resistance to evaporation. The kinematic viscosity of medium viscosity PAO (A1-2) at 40°C is 60 mmHg. ２ When the coefficient of viscosity is less than or equal to / s, the torque reduction performance is excellent. In the grease composition of this embodiment, the viscosity index of the medium viscosity PAO (A1-2) is preferably 110 or higher, more preferably 120 or higher, and even more preferably 130 or higher. When the viscosity index of the medium viscosity PAO (A1-2) is 110 or higher, the effects of the present invention are more easily improved.

[0028] <<High Viscosity PAO (A1-3)>> As for the high viscosity PAO (A1-3), any PAO with a kinematic viscosity at 40°C within a predetermined range can be used without particular limitation. In the grease composition of this embodiment, the kinematic viscosity at 40°C of the high viscosity PAO (A1-3) is preferably 200 mm. ２ / s or more 700mm ２ / s or less, more preferably 250 mm ２ / s or more 600mm ２ / s or less, more preferably 300 mm ２ / s or more 500mm ２ / s or less, more preferably 350 mm ２ / s or more 450mm ２ It is less than / s. The kinematic viscosity of high viscosity PAO (A1-3) at 40°C is 200 mm². ２ If the kinematic viscosity is 700 mmHg or higher, it exhibits excellent resistance to evaporation. The kinematic viscosity of high-viscosity PAO (A1-3) at 40°C is 700 mmHg. ２When the coefficient of viscosity is less than or equal to / s, the torque reduction performance is excellent. In the grease composition of this embodiment, the viscosity index of the high viscosity PAO (A1-3) is preferably 120 or higher, more preferably 130 or higher, and even more preferably 140 or higher. When the viscosity index of the high viscosity PAO (A1-3) is 120 or higher, the effects of the present invention are more easily improved.

[0029] <<Ester-based synthetic oil (A2)>> The base oil (A) preferably contains an ester-based synthetic oil (A2). The ester-based synthetic oil (A2) preferably contains one or more selected from diester oils, aromatic ester oils, polyol ester oils, and complex ester oils. Examples of the diester oils include dibutyl sebacate, dioctyl sebacate, di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, ditridecyl glutarate, and methylacetyl ricinolate. Examples of the aromatic ester oils include trioctyl trimellitate, tridecyl trimellitate, and tetraoctyl pyromelitate. Examples of the polyol ester oils include trimethylolpropane caprylate, trimethylolpropane veralgonate, pentaerythritol-2-ethylhexanoate, and pentaerythritol veralgonate. Examples of the complex ester oils include oligoesters of polyhydric alcohols and mixed fatty acids of dibasic and monobasic acids. These may be used individually or in combination of two or more.

[0030] The kinematic viscosity of the ester-based synthetic oil (A2) at 40°C is preferably 5 mm². ２ / s or more 40mm ２ / s or less, more preferably 6 mm ２ / s or more 30mm ２ / s or less, more preferably 8 mm ２ / s or more 20mm ２ / s or less, more preferably 10 mm ２ / s or more 15mm ２ It is less than / s. The kinematic viscosity of the ester-based synthetic oil (A2) at 40°C is 5 mm². ２ / s or more 40mm２ If the viscosity index is less than or equal to / s, the effects of the present invention can be more easily improved. The viscosity index of the ester-based synthetic oil (A2) is preferably 120 or higher, more preferably 130 or higher, and even more preferably 140 or higher. If the viscosity index of the ester-based synthetic oil (A2) is 120 or higher, the effects of the present invention can be more easily improved.

[0031] The content of ester-based synthetic oil (A2) in base oil (A) is 2.0% by mass or more and 12.0% by mass or less, preferably 2.5% by mass or more and 11.8% by mass or less, more preferably 3.0% by mass or more and 11.5% by mass or less, and even more preferably 4.0% by mass or more and 11.0% by mass or less, based on the total amount of base oil (A).

[0032] The total content of PAO (A1) and ester-based synthetic oil (A2) is preferably 60% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, even more preferably 80% by mass or more and 100% by mass or less, even more preferably 90% by mass or more and 100% by mass or less, and still more preferably 95% by mass or more and 100% by mass or less, based on the total amount of base oil (A).

[0033] From the viewpoint of material compatibility, the content ratio [(A1) / (A2)] of PAO (A1) to ester-based synthetic oil (A2) is preferably 1.0 to 20.0, more preferably 5.0 to 17.0, even more preferably 8.0 to 14.0, and even more preferably 10.0 to 13.0 by mass ratio.

[0034] <<Olefin Copolymer (A3)>> The base oil (A) preferably contains an olefin copolymer (A3). There are no particular restrictions on the olefin copolymer (A3), and examples include ethylene-propylene copolymer, ethylene-butylene copolymer, styrene-isoprene copolymer, styrene-butadiene copolymer, etc. The number average molecular weight of the olefin copolymer (A3) is preferably 300 to 20,000, more preferably 500 to 15,000, and even more preferably 800 to 12,000.

[0035] In the grease composition of this embodiment, the base oil (A) may contain base oils other than PAO (A1) and ester-based synthetic oil (A2). Examples of such other base oils include one or more selected from mineral oil and synthetic oils other than PAO (A1) and ester-based synthetic oil (A2).

[0036] Examples of mineral oils include atmospheric residue obtained by atmospheric distillation of crude oil such as paraffinic crude oil, intermediate crude oil, and naphthenic crude oil; distillate obtained by vacuum distillation of the atmospheric residue; and mineral oil obtained by subjecting the distillate to one or more refining treatments such as solvent dewaxing, solvent extraction, hydrotrining, hydrocracking, advanced hydrocracking, solvent dewaxing, catalytic dewaxing, and hydroisomerization dewaxing.

[0037] Other synthetic oils besides PAO (A1) and ester-based synthetic oils (A2) include, for example, normal paraffins, isoparaffins, aromatic oils, ether-based oils, and synthetic oils obtained by isomerizing waxes produced by the Fischer-Tropsch process (GTL waxes). These may be used individually or in combination of two or more.

[0038] Examples of aromatic oils include alkylbenzenes such as monoalkylbenzene and dialkylbenzene; alkylnaphthalenes such as monoalkylnaphthalene, dialkylnaphthalene, and polyalkylnaphthalene; and so on.

[0039] Examples of ether-based oils include polyglycols such as polyethylene glycol, polypropylene glycol, polyethylene glycol monoether, and polypropylene glycol monoether; and phenyl ether-based oils such as monoalkyltriphenyl ether, alkyldiphenyl ether, dialkyldiphenyl ether, pentaphenyl ether, tetraphenyl ether, monoalkyltetraphenyl ether, and dialkyltetraphenyl ether.

[0040] In the grease composition of this embodiment, the kinematic viscosity of the base oil (A) at 40°C is preferably 5 mm². ２ / s or more 55mm ２ / s or less, more preferably 10 mm ２ / s or more and 53 mm ２ / s or less, more preferably 15 mm ２ / s or more and 50 mm ２ / s or less, still more preferably 18 mm ２ / s or more and 48 mm ２ / s or less, even still more preferably 20 mm ２ / s or more and 42 mm ２ / s or less, even more preferably 20 mm ２ / s or more and 35 mm ２ / s or less. When the kinematic viscosity at 40°C of the base oil (A) is 5 mm ２ / s or more, the evaporation resistance is excellent. When the kinematic viscosity at 40°C of the base oil (A) is 55 mm ２ / s or less, the torque reduction property is excellent. In the grease composition of the present embodiment, the kinematic viscosity at 100°C of the base oil (A) is preferably 2.0 mm ２ / s or more and 12.0 mm ２ / s or less, more preferably 3.0 mm ２ / s or more and 10.0 mm ２ / s or less, still more preferably 4.0 mm ２ / s or more and 9.0 mm ２ / s or less. In the grease composition of the present embodiment, the viscosity index of the base oil (A) is preferably 110 or more, more preferably 120 or more, and still more preferably 130 or more. In the present specification, the kinematic viscosity at 40°C, kinematic viscosity at 100°C, and viscosity index mean values measured or calculated in accordance with JIS K2283:2000.

[0041] In the grease composition of the present embodiment, the content of the base oil (A) is, based on the total amount (100% by mass) of the grease composition, preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 75% by mass or more, even more preferably 80% by mass or more, and also preferably 97% by mass or less, more preferably 95% by mass or less, still more preferably 93% by mass or less, even more preferably 90% by mass or less.

[0042] <Thickener (B)> The grease composition of the present embodiment contains a thickener (B). Furthermore, the thickener (B) is at least one selected from one or more urea-based thickeners (B1) selected from diurea compounds represented by the following general formula (b1), and lithium soap (B2), R １ -NHCONH-R ３ -NHCONH-R ２ (b1) [In the above general formula (b1), R １ and R ２ each independently represent a monovalent chain hydrocarbon group or alicyclic hydrocarbon group having 6 to 24 carbon atoms. R １ and R ２ may be the same or different from each other. R ３ represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms.] When the content of chain hydrocarbon groups in R １ and R ２ in the general formula (b1) is defined as X molar equivalent, and the content of alicyclic hydrocarbon groups is defined as Y molar equivalent, the following requirement (1) is satisfied: - Requirement (1): The X / Y ratio is 3 / 2 or more. The Young's modulus of the thickener (B) is 1.4 GPa or less.

[0043] [Young's Modulus] The Young's modulus of the thickener (B) is 1.4 GPa or less. Young's modulus is an indicator of the hardness of the thickener (B), which is a solid component contained in the grease composition. In the grease composition of the present embodiment, the thickener (B) has a low Young's modulus of 1.4 GPa or less and is soft. Therefore, a grease composition excellent in torque reduction performance can be obtained. From the viewpoint of torque reduction, the Young's modulus of the thickener (B) is 1.4 GPa or less, preferably 1.3 GPa or less, more preferably 1.2 GPa or less, and still more preferably 1.1 GPa or less. The Young's modulus of the thickener (B) can be measured by the method described in Examples.

[0044] <<Urea-based Thickener (B1)>> The urea-based thickener (B1) is one or more selected from diurea compounds represented by the following general formula (b1). R １ -NHCONH-R ３ -NHCONH-R２ (b1) [In the above general formula (b1), R １ and R ２ Each of these independently represents a monovalent chain hydrocarbon group or alicyclic hydrocarbon group having 6 to 24 carbon atoms. １ and R ２ They may be the same or they may be different from one another. ３ This represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms.

[0045] R in the above general formula (b1) １ and R ２ The number of carbon atoms in the monovalent chain hydrocarbon group or alicyclic hydrocarbon group that can be selected is 6 to 24, preferably 6 to 20, and more preferably 6 to 18. １ and R ２ Examples of monovalent chain hydrocarbon groups that can be selected include saturated or unsaturated monovalent chain hydrocarbon groups, but saturated chain hydrocarbon groups are preferred. １ and R ２ Examples of monovalent alicyclic hydrocarbon groups that can be selected include saturated or unsaturated monovalent alicyclic hydrocarbon groups, but saturated alicyclic hydrocarbon groups are preferred. R in the general formula (b1) １ and R ２ The monovalent hydrocarbon group that can be selected may include a diurea compound containing a monovalent aromatic hydrocarbon group.

[0046] The grease composition of this embodiment is R in the general formula (b1) １ and R ２ In this product, when the content of chain hydrocarbon groups is X molar equivalents and the content of alicyclic hydrocarbon groups is Y molar equivalents, the following requirement (1) is met. Requirement (1): The X / Y ratio is 3 / 2 or more. When the X / Y ratio is 3 / 2 or more, the torque reduction performance is excellent. Here, from the viewpoint of torque reduction performance, the X / Y ratio specified in requirement (1) is preferably 65 / 35 or more, more preferably 75 / 25 or more.

[0047] Furthermore, the grease composition of this embodiment contains R in the above general formula (b1). １ and R ２In the present invention, when the content of chain hydrocarbon groups is X molar equivalents, the content of alicyclic hydrocarbon groups is Y molar equivalents, and the content of aromatic hydrocarbon groups is Z molar equivalents, it is preferable to satisfy the following requirement (2) from the viewpoint of making it easier to improve the effects of the present invention. Requirement (2): The value of [(X + Y) / (X + Y + Z)] × 100 is 90 or more (preferably 95 or more, more preferably 98 or more, and even more preferably 100).

[0048] Furthermore, the alicyclic hydrocarbon group, the chain hydrocarbon group, and the aromatic hydrocarbon group are R in the general formula (b1) above. １ and R ２ Since it is a group selected as such, the sum of the values ​​of X, Y, and Z is 2 molar equivalents per mole of the compound represented by the general formula (b1) above. Furthermore, the values ​​of requirements (1) and (2) above represent the average value of the total amount of the compound group represented by the general formula (b1) above contained in the grease composition. By using a compound represented by the general formula (b1) above that satisfies requirement (1) above, and preferably requirement (2) above, it is easy to obtain a grease composition with excellent miscibility at 25°C. Note that the values ​​of X, Y, and Z can be calculated from the molar equivalents of each amine used as a raw material.

[0049] Examples of monovalent saturated hydrocarbon groups include linear or branched alkyl groups having 6 to 24 carbon atoms. Specifically, these include hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl (stearyl), octadecenyl, nonadecyl, and eicosyl groups. The monovalent saturated hydrocarbon group may be linear or branched. Among these, the octadecyl (stearyl) group is preferred.

[0050] Examples of monovalent unsaturated hydrocarbon groups include linear or branched alkenyl groups having 6 to 24 carbon atoms. Specifically, these include hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, nonadecenyl, icocenyl, oleyl, geranyl, farnesyl, and linoleyl groups. Note that monovalent unsaturated hydrocarbon groups may be linear or branched.

[0051] Examples of monovalent saturated alicyclic hydrocarbon groups include cycloalkyl groups such as cyclohexyl, cycloheptyl, cyclooctyl, and cyclononyl groups; and cycloalkyl groups substituted with C1-C6 alkyl groups such as methylcyclohexyl, dimethylcyclohexyl, ethylcyclohexyl, diethylcyclohexyl, propylcyclohexyl, isopropylcyclohexyl, 1-methylpropylcyclohexyl, butylcyclohexyl, pentylcyclohexyl, pentylmethylcyclohexyl, and hexylcyclohexyl groups (preferably cyclohexyl groups substituted with C1-C6 alkyl groups). Among these, the cyclohexyl group is preferred.

[0052] Examples of monovalent unsaturated alicyclic hydrocarbon groups include cycloalkenyl groups such as cyclohexenyl, cycloheptenyl, and cyclooctenyl groups; and cycloalkenyl groups substituted with C1-C6 alkyl groups such as methylcyclohexenyl, dimethylcyclohexenyl, ethylcyclohexenyl, diethylcyclohexenyl, and propylcyclohexenyl groups (preferably cyclohexenyl groups substituted with C1-C6 alkyl groups).

[0053] Examples of monovalent aromatic hydrocarbon groups include phenyl, biphenyl, terphenyl, naphthyl, diphenylmethyl, diphenylethyl, diphenylpropyl, methylphenyl, dimethylphenyl, ethylphenyl, and propylphenyl groups.

[0054] R in the above general formula (b1) ３ The number of carbon atoms in the divalent aromatic hydrocarbon group that can be selected is 6 to 18, preferably 6 to 15, and more preferably 6 to 13. ３ Examples of divalent aromatic hydrocarbon groups that can be selected include phenylene group, diphenylmethylene group, diphenylethylene group, diphenylpropylene group, methylphenylene group, dimethylphenylene group, and ethylphenylene group. Among these, phenylene group, diphenylmethylene group, diphenylethylene group, or diphenylpropylene group are preferred, and diphenylmethylene group is more preferred.

[0055] In the grease composition of this embodiment, the content of the urea-based thickener (B1) is preferably 1.0 to 20.0% by mass, more preferably 3.0 to 18.0% by mass, even more preferably 5.0 to 16.0% by mass, even more preferably 7.0 to 15.0% by mass, and still more preferably 9.0% to 13.0% by mass, based on the total amount (100% by mass) of the grease composition, from the viewpoint of making the hardness of the grease composition within an appropriate range.

[0056] [Requirement (I)] From the viewpoint of further improving the effects of the present invention, it is preferable that the particles containing the urea-based thickener (B1) in the grease composition of this embodiment satisfy the following requirement (I). Requirement (I): The arithmetic mean particle diameter on an area basis when the particles are measured by laser diffraction / scattering is 2.0 μm or less.

[0057] The above requirement (I) can also be considered a parameter indicating the state of aggregation of the urea-based thickener (B1) in the grease composition. Here, the "particles containing the urea-based thickener (B1)" to be measured by laser diffraction / scattering refers to particles formed by the aggregation of the urea-based thickener (B1) contained in the grease composition. Although the grease composition may contain additives other than the urea-based thickener (B1), the arithmetic mean particle size specified in the above requirement (I) can be obtained by measuring a grease composition prepared under the same conditions without the additive using laser diffraction / scattering. However, if the additive is liquid at room temperature (25°C) or dissolves in the base oil (A), the grease composition containing the additive may also be used as the measurement target.

[0058] Urea-based thickeners (B1) are usually obtained by reacting an isocyanate compound with a monoamine, but because the reaction rate is very fast, the urea-based thickener (B1) tends to aggregate, and large particles (micelle particles, so-called "clumps") are easily generated in excess. It is presumed that by refining the arithmetic mean particle size specified in requirement (I) above to 2.0 μm or less, the particles containing the urea-based thickener (B1) become easier to penetrate into the lubrication area (friction surface) and are also more difficult to remove from the lubrication area, thereby improving the retention capacity of the grease composition in the lubrication area. From the above viewpoint, in the grease composition of this embodiment, the arithmetic mean particle size defined in requirement (I) above is preferably 1.5 μm or less, more preferably 1.0 μm or less, even more preferably 0.9 μm or less, even more preferably 0.8 μm or less, even more preferably 0.7 μm or less, even more preferably 0.6 μm or less, even more preferably 0.5 μm or less, and even more preferably 0.4 μm or less. Also, it is usually 0.01 μm or more.

[0059] [Requirement (II)] From the viewpoint of further improving the effects of the present invention, it is preferable that the particles containing the urea-based thickener (B1) in the grease composition of this embodiment further satisfy the following requirement (II). Requirement (II): The specific surface area of ​​the particles when measured by laser diffraction / scattering method is 0.5 × 10５ cm ２ / cm ３ That's all.

[0060] The specific surface area specified in requirement (II) above is a secondary indicator of the state of particle refinement of the urea-based thickener (B1) particles in the grease composition and the presence of large particles (clumps). That is, satisfying requirement (I) above and further satisfying requirement (II) above indicates that the state of particle refinement of the urea-based thickener (B1) particles in the grease composition is better and the presence of large particles (clumps) is more suppressed. From the above viewpoint, the specific surface area specified in requirement (II) above is preferably 0.7 × 10⁻⁶. ５ cm ２ / cm ３ More preferably 0.8 × 10 ５ cm ２ / cm ３ More preferably 1.2 × 10 ５ cm ２ / cm ３ More preferably 1.5 × 10 ５ cm ２ / cm ３ More preferably 1.8 × 10 ５ cm ２ / cm ３ More preferably 2.0 × 10 ５ cm ２ / cm ３ That's all. Note that the specific surface area is typically 1.0 × 10⁻⁶. ６ cm ２ / cm ３ The following applies:

[0061] The values ​​specified in requirement (I) and further in requirement (II) above can be adjusted mainly by the manufacturing conditions of the urea-based thickener (B1).

[0062] [Method for producing urea-based thickener (B1)] Urea-based thickener (B1) can usually be obtained by reacting an isocyanate compound with a monoamine. The reaction is preferably carried out by adding a solution β, in which a monoamine is dissolved in the base oil (A), to a heated solution α obtained by dissolving the isocyanate compound in the base oil (A) as described above. For example, when synthesizing the compound represented by the general formula (b1), the isocyanate compound is R in the general formula (b1). ３ A diisocyanate having a group corresponding to the divalent aromatic hydrocarbon group shown is used, and as the monoamine, R １ and R ２ Using an amine having a group corresponding to the monovalent hydrocarbon group shown, the desired urea-based thickener (B1) can be synthesized by the above method.

[0063] Furthermore, from the viewpoint of micronizing the urea-based thickener (B1) in the grease composition so as to satisfy the above requirement (I), preferably requirement (II), the grease composition of this embodiment is preferably manufactured by carrying out a grease formation reaction while applying a high shear rate to the urea-based thickener (B1) or its precursor in the base oil (A). Alternatively, the grease formation reaction can be carried out by applying a predetermined high shear rate after the base oil (A) has been made into a mixed base oil. High-speed shearing can be carried out in a manufacturing apparatus or the like equipped with a high-speed rotating part inside the container. It is applied to the mixed liquid in the gap between the high-speed rotating part and the inner wall of the container. The gap between the high-speed rotating part and the inner wall of the container may be constant (uniform) in all parts, or it may be a non-uniform structure. Such a gap may be adjusted by changing the diameter of the high-speed rotating part in the direction of rotation axis, or by making the high-speed rotating part frustoconical and moving this high-speed rotating part up and down relative to the inner wall of the reaction vessel which has a taper. Furthermore, the larger gaps may be given an extrusion capability by creating a screw or spiral shape with continuous inclination. Note that when manufacturing using equipment arranged in the rotational direction, the larger gaps can be given an extrusion capability similar to a screw by inclining them with respect to the rotation axis.

[0064] From the viewpoint of applying uniform high-speed shear, the shearing time is preferably 0.1 seconds or longer, and more preferably 1 second or longer.

[0065] The temperature inside the manufacturing apparatus is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher, as this makes it less likely for isocyanates and amines, which are precursors of thickeners, to precipitate from the base oil, resulting in excellent dispersibility and reaction rate. Furthermore, the temperature inside the manufacturing apparatus is preferably 200°C or lower, more preferably 190°C or lower, and even more preferably 180°C or lower, from the viewpoint of preventing deterioration of the base oil and appropriately controlling the reaction rate.

[0066] To produce a grease containing a urea-based thickener (B1), a grease base material containing the urea-based thickener (B1) can be produced by introducing solutions α and β, which are grease raw materials, and rotating a rotor at high speed. Even if an additive (C) is added to the obtained grease base material, the effect of additive (C) is not easily inhibited, and the urea-based thickener (B1) in the grease composition can be finely milled to preferably satisfy requirement (I), and more preferably requirement (II) above.

[0067] As a condition for high-speed rotation of the rotor, the shear rate applied to the grease raw material is preferably 10 ２ s －１ The above is more 10 ３ s －１ More preferably 10 ４ s －１ The above is the case. The higher the shear rate, the better the dispersion of the urea-based thickener (B1), resulting in a more uniform grease composition. Furthermore, the shear rate should be set to 10 from the viewpoint of the safety of the device and the heat generated by shearing and its removal. ７ s －１ The following is preferable. Such a shear rate can be imparted by introducing a mixed liquid into a manufacturing apparatus that generates shear through relative motion between opposing wall surfaces.

[0068] The ratio of the maximum shear rate (Max) to the minimum shear rate (Min) during high-speed rotation of the rotor (Max / Min) is preferably 100 or less, more preferably 50 or less, and even more preferably 10 or less. By making the shear rate as uniform as possible with respect to the mixed liquid, it becomes easier to refine the urea-based thickener (B1) and its precursors in the grease composition, resulting in a more uniform grease structure.

[0069] Here, the maximum shear rate (Max) is the highest shear rate applied to the mixture, and the minimum shear rate (Min) is the lowest shear rate applied to the mixture, as defined below: • Maximum shear rate (Max) = (Linear velocity of the surface of the high-speed rotating part at the point where the gap between the surface of the high-speed rotating part and the inner wall of the container is smallest / said gap) • Minimum shear rate (Min) = (Linear velocity of the surface of the high-speed rotating part at the point where the gap between the surface of the high-speed rotating part and the inner wall of the container is largest / said gap)

[0070] <<Lithium soap (B2)>> Examples of lithium soap (B2) include one or more selected from lithium stearate and lithium 12-hydroxystearate.

[0071] In the grease composition of this embodiment, the lithium soap (B2) content is preferably 1.0 to 20.0% by mass, more preferably 3.0 to 18.0% by mass, even more preferably 5.0 to 16.0% by mass, even more preferably 7.0 to 15.0% by mass, and still more preferably 9.0% to 13.0% by mass, based on the total amount (100% by mass) of the grease composition, from the viewpoint of making the hardness of the grease composition within an appropriate range.

[0072] In the grease composition of this embodiment, the content of the thickener (B) is preferably 1.0 to 20.0% by mass, more preferably 3.0 to 18.0% by mass, even more preferably 5.0 to 16.0% by mass, even more preferably 7.0 to 15.0% by mass, and still more preferably 9.0% to 13.0% by mass, based on the total amount (100% by mass) of the grease composition, from the viewpoint of making the hardness of the grease composition within an appropriate range.

[0073] <Additive (C)> The grease composition of this embodiment may contain additives (C) other than component (B) that are commonly used in greases, as long as they do not impair the effects of the present invention. Examples of additives (C) include dispersants, antioxidants, extreme pressure agents, and rust inhibitors. Additives (C) may be used individually or in combination of two or more. The grease composition of this embodiment preferably contains one or more additives (C) selected from dispersants, antioxidants, extreme pressure agents, and rust inhibitors.

[0074] - Dispersants - Examples of dispersants include aprotic polar solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); alcohols such as propanol, ethylene glycol, propylene glycol, and hexylene glycol; and surfactants such as polyglycerin fatty acid esters, sucrose fatty acid esters, citrate monoglycerides, diacetyltartaric acid monoglycerides, polyoxyethylene sorbitanate esters, and sorbitanate esters. Specifically, examples include sorbitan triolate, succinic acid half-ester, urea, and various surfactants. These may be used individually or in combination of two or more.

[0075] - Antioxidants - Examples of antioxidants include amine-based antioxidants and phenol-based antioxidants. Among these, phenol-based antioxidants are preferred. Examples of amine-based antioxidants include diphenylamine compounds and naphthylamine compounds. Examples of diphenylamine compounds include monoalkyldiphenylamine compounds having one C1-C30 alkyl group, such as monooctyldiphenylamine and monononyldiphenylamine; dialkyldiphenylamine compounds having two C1-C30 alkyl groups, such as 4,4'-dibutyldiphenylamine, 4,4'-dipentyldiphenylamine, 4,4'-dihexyldiphenylamine, 4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, and 4,4'-dinonyldiphenylamine; polyalkyldiphenylamine compounds having three or more C1-C30 alkyl groups, such as tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, and tetranonyldiphenylamine; and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine. Examples of naphthylamine compounds include 1-naphthylamine, phenyl-1-naphthylamine, butylphenyl-1-naphthylamine, pentylphenyl-1-naphthylamine, hexylphenyl-1-naphthylamine, heptylphenyl-1-naphthylamine, octylphenyl-1-naphthylamine, nonylphenyl-1-naphthylamine, decylphenyl-1-naphthylamine, and dodecylphenyl-1-naphthylamine.Examples of phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,4,6-tri-t-butylphenol, 2,6-di-t-butyl-4-hydroxymethylphenol, 2,6-di-t-butylphenol, 2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-(N,N-dimethylaminomethyl)phenol, 2,6-di-t-amyl-4-methylphenol, and n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propio Examples include monocyclic phenolic compounds such as nates, and polycyclic phenolic compounds such as 4,4'-methylenebis(2,6-di-t-butylphenol), 4,4'-isopropylidenebis(2,6-di-t-butylphenol), 2,2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-bis(2,6-di-t-butylphenol), 4,4'-bis(2-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), and 4,4'-butylidenebis(3-methyl-6-t-butylphenol). These may be used individually or in combination of two or more.

[0076] -Extreme Pressure Agents- Examples of extreme pressure agents include phosphorus compounds, zinc dithiophosphate, and organic molybdenum. These may be used individually or in combination of two or more.

[0077] -Rust Inhibitors- Examples of rust inhibitors include ester-based rust inhibitors, carboxylic acid-based rust inhibitors, zinc stearate, thiadiazole and its derivatives, benzotriazole and its derivatives, fatty acid soaps, alkyl sulfonates, fatty acid amines, oxidized paraffins, alkyl polyoxyethylene ethers, etc. Examples of ester-based rust inhibitors include glycerin monooleate, glycerin dioleate, glycerin trioleate, alkenyl succinate half-esters, and alkenyl succinate polyhydric alcohol esters. Examples of carboxylic acid-based rust inhibitors include octanoic acid, heptanoic acid, and nonanoic acid. Among these, octanoic acid is preferred. These may be used individually or in combination of two or more.

[0078] In the grease composition of this embodiment, the content of additive (C) is preferably 0.01% to 15% by mass, more preferably 0.05% to 10% by mass, even more preferably 0.10% to 7% by mass, and even more preferably 0.50% to 6% by mass, based on the total amount (100% by mass) of the grease composition.

[0079] [Physical Properties of the Grease Composition] <Divisibility> The divisibility of the grease composition of this embodiment is preferably 175 to 385, more preferably 220 to 385, even more preferably 220 to 340, and even more preferably 265 to 295, from the viewpoint of making the hardness of the grease composition within an appropriate range. In this specification, divisibility means the value measured at 25°C in accordance with JIS K2220:2013 (Clause 7).

[0080] <Torque Reduction Properties> The torque reduction properties of the grease composition of this embodiment can be evaluated by measuring the rotational torque by the method described in the examples below. In this specification, the rotational torque of the grease composition refers to the rotational torque (unit: mN·m) measured at a temperature of 25°C. The rotational torque is the torque required for power to be continuously output, and a smaller value is preferable. The rotational torque of the grease composition of this embodiment at 25°C is preferably 60 mN·m or less, more preferably 50 mN·m or less, and even more preferably 40 mN·m or less.

[0081] [Adjustment Method] The adjustment method of this embodiment is to adjust the Young's modulus of the thickener (B) to 1.4 GPa or less by selecting one or more urea-based thickeners (B1) selected from diurea compounds represented by the following general formula (b1), and / or one or more thickeners (B) selected from lithium soap (B2). １ -NHCONH-R ３ -NHCONH-R ２ (b1) [In the above general formula (b1), R １ and R ２ Each of these independently represents a monovalent chain hydrocarbon group or alicyclic hydrocarbon group having 6 to 24 carbon atoms. １ and R ２ They may be the same or they may be different from one another. ３ R represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ] In the above general formula (b1) R １ and R ２ In this mixture, when the content of chain hydrocarbon groups is X molar equivalents and the content of alicyclic hydrocarbon groups is Y molar equivalents, the following requirement (1) is met: Requirement (1): The X / Y ratio is 3 / 2 or more. Additive (C) may be added as needed. The preferred embodiments of the base oil (A), thickener (B), and additive (C) are as described above. Furthermore, the amounts and ratios of the base oil (A), thickener (B), and additive (C) are preferably amounts corresponding to the preferred content of the base oil (A), thickener (B), and additive (C) as described above.

[0082] [Method for producing a grease composition] The method for producing a grease composition of the present invention is a method for producing a grease composition that includes the step of carrying out the preparation method described above.

[0083] As an example of the above manufacturing method, the diurea compound represented by the above general formula (b1) can usually be obtained by reacting a diisocyanate with a monoamine. In this reaction, it is preferable to add a base oil in which a diisocyanate is dissolved in the mixed base oil of PAO (A1) and ester-based synthetic oil (A2), which is heated and dissolved, while heating and stirring the monoamine-containing base oil, and then adding an olefin copolymer (A3) and raising the temperature. For example, when synthesizing the diurea compound represented by the above general formula (b1), the diisocyanate is R in the above general formula (b1). ３ A diisocyanate having a group corresponding to the divalent aromatic hydrocarbon group shown is used, and as the monoamine, R １ and R ２ A desired diurea compound can be synthesized by the above method using an amine having a group corresponding to a monovalent chain hydrocarbon group or an alicyclic hydrocarbon group as shown above. After the above step, an additive (C) may be added to the base grease as needed. The preferred embodiments of the base oil (A), thickener (B), and additive (C) are as described above. Furthermore, the amounts and ratios of the base oil (A), thickener (B), and additive (C) are preferably such that they correspond to the preferred content of the base oil (A), thickener (B), and additive (C) as described above.

[0084] [Uses of the Grease Composition] Fields of equipment in which the grease composition of the present invention can be suitably used include the railway, bicycle, automobile, office equipment, machine tool, wind turbine, construction, agricultural machinery, or industrial robot fields. Examples of lubrication parts in automotive equipment in which the grease composition of the present invention can be suitably used include bearing parts in equipment such as radiator fan motors, fan couplings, alternators, idler pulleys, hub units, water pumps, power windows, wipers, electric power steering, drive motor flywheels, ball joints, wheel bearings, spline sections, and constant velocity joints; bearing parts, gear sections, and sliding parts in equipment such as door locks, door hinges, and clutch boosters; and more specifically, railway vehicles, main motors, hub units, electric power steering, drive motor flywheels, ball joints, wheel bearings, spline sections, constant velocity joints, clutch boosters, servo motors, blade bearings, or bearing parts of generators. The grease composition of this embodiment can be suitably used for lubricating hub bearings.

[0085] Examples of lubrication parts in equipment in the office equipment field where the grease composition of this embodiment can be suitably used include, for example, fixing rolls in equipment such as printers, bearings and gear parts in equipment such as polygon motors. Examples of lubrication parts in equipment in the machine tool field where the grease composition of the present invention can be suitably used include, for example, spindles, servo motors, and bearing parts in reduction gears of machine robots. Examples of lubrication parts in equipment in the wind turbine field where the grease composition of the present invention can be suitably used include, for example, blade bearings and bearing parts of generators. Examples of lubrication parts in equipment in the construction or agricultural machinery field where the grease composition of the present invention can be suitably used include, for example, ball joints, bearing parts such as spline sections, gear parts and sliding parts.

[0086] [One aspect of the present invention provided] According to one aspect of the present invention, the following [1] to [7] are provided. [1] A base oil (A) and a thickener (B), wherein the thickener (B) is one or more urea-based thickeners (B1) selected from diurea compounds represented by the following general formula (b1), and one or more lithium soaps (B2), R １ -NHCONH-R ３ -NHCONH-R ２ (b1) [In the above general formula (b1), R １ and R ２ Each of these independently represents a monovalent chain hydrocarbon group or alicyclic hydrocarbon group having 6 to 24 carbon atoms. １ and R ２ They may be the same or they may be different from one another. ３ R represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ] In the above general formula (b1) R １ and R ２ [1] A grease composition in which the content of chain hydrocarbon groups is X molar equivalents and the content of alicyclic hydrocarbon groups is Y molar equivalents, satisfying the following requirement (1): The X / Y ratio is 3 / 2 or more. The Young's modulus of the thickener (B) is 1.4 GPa or less. [2] The grease composition according to [1], wherein the lithium soap (B2) is one or more selected from lithium stearate and lithium 12-hydroxystearate. [3] The kinematic viscosity of the base oil (A) at 40°C is 15 mm ２ / s ~ 50mm ２ A grease composition according to [1] or [2] above, wherein the ratio is / s. [4] A grease composition according to any one of [1] to [3] above, wherein the miscible consistency at 25°C is 265 to 295. [5] A grease composition according to any one of [1] to [4] above, used for lubricating hub bearings. [6] A method for adjusting the Young's modulus of the thickener (B) to 1.4 GPa or less by selecting one or more urea-based thickeners (B1) selected from diurea compounds represented by the following general formula (b1), and / or one or more thickeners (B) selected from lithium soap (B2).１ -NHCONH-R ３ -NHCONH-R ２ (b1) [In the above general formula (b1), R １ and R ２ Each of these independently represents a monovalent chain hydrocarbon group or alicyclic hydrocarbon group having 6 to 24 carbon atoms. １ and R ２ They may be the same or they may be different from one another. ３ R represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ] In the above general formula (b1) R １ and R ２ In the above, when the content of chain hydrocarbon groups is X molar equivalents and the content of alicyclic hydrocarbon groups is Y molar equivalents, the following requirement (1) is satisfied. Requirement (1): The X / Y ratio is 3 / 2 or more. [7] A method for producing a grease composition, comprising the step of carrying out the preparation method described in [6] above.

[0087] The present invention will be specifically described by the following embodiments. However, the present invention is not limited to the following embodiments.

[0088] [Method for measuring physical properties] The properties of each raw material used in each example and comparative example, as well as the properties of the lubricating oil compositions in each example and comparative example, were measured according to the following procedure.

[0089] (1) The kinematic viscosity at 40°C, the kinematic viscosity at 100°C, and the viscosity index of the base oil (A) (mixed base oil) used in the preparation of the grease composition were measured or calculated in accordance with JIS K2283:2000.

[0090] (2) Young's Modulus of Thickener (B) The Young's modulus of thickener (B) for each grease composition was measured using a nanoindenter (product name: Ultra-micro indentation hardness tester ENT-1100b / a, manufactured by Elionix Co., Ltd.) under the following measurement conditions. This test was performed 10 times, and the average value was taken as the Young's modulus. - Measurement conditions - Sample size: 10 mm in diameter, 0.5 mm in thickness Test load: 5 mN Test reach time: 5 seconds Test holding time: 10 seconds Measurement temperature: Room temperature (25°C)

[0091] (3) Mixing consistency The mixing consistency of each grease composition was measured at 25°C in accordance with JIS K2220:2013 (Clause 7).

[0092] [Examples 1-9 and Comparative Examples 1-4] Grease compositions of Examples 1-9 and Comparative Examples 1-4 were prepared by the methods described below, and these grease compositions were evaluated as described later.

[0093] The components included in Examples 1 to 9 and Comparative Examples 1 to 4 are as follows:

[0094] <Base oil (A)> Low viscosity, low evaporative PAO (A1-1) (Poly-α-olefin (PAO), kinematic viscosity at 40°C: 14.3 mm) ２ ( / s, viscosity index: 129) Medium viscosity PAO (A1-2) (poly-α-olefin (PAO), kinematic viscosity at 40°C: 30.7 mm) ２ ( / s, viscosity index: 135) High viscosity PAO (A1-3) (poly-α-olefin (PAO), kinematic viscosity at 40°C: 396 mmHg) ２ ( / s, viscosity index: 147) Ester-based synthetic oil (A2) (dioctyl sebacate (diester), kinematic viscosity at 40°C: 11.6 mm) ２ ( / s, viscosity index: 153) • Olefin copolymer (A3) (ethylene-propylene copolymer, number average molecular weight: 1,000 or more and less than 10,000)

[0095] <Additive (C)> The following components were used as additive (C).

[0096] - Dispersant - Dispersant (C1): Product name "OLOA340DT" (manufactured by Chevron Japan Co., Ltd.)

[0097] - Antioxidants - Antioxidant (C2-1): Product name "Naugalube® 438L" (manufactured by Lanxess) Antioxidant (C2-2): Diethyl (3,5-di-t-butyl-4-hydroxybenzyl)phosphonate (product name: JC-356, manufactured by Johoku Chemical Industry Co., Ltd.) Antioxidant (C2-3): Product name "Antigen PA" (manufactured by Sumitomo Chemical Co., Ltd.)

[0098] - Extreme Pressure Agents - • Extreme pressure agent (C3): Product name "HiTEC® 317" (manufactured by Afton Chemical Japan Co., Ltd.)

[0099] - Rust Inhibitors - Rust Inhibitor (C4-1): Product name "HiTEC (registered trademark) 4313" (manufactured by Afton Chemical Japan Co., Ltd.) Rust Inhibitor (C4-2): Octanoic acid, product name "Lunaq 8-98" (manufactured by Kao Corporation) Rust Inhibitor (C4-3): Product name "K-KORR G-1340" (manufactured by KING INDUSTRIES)

[0100] (Example 1) (1) Synthesis of Urea Grease Solution α was prepared by adding 3.90 parts by mass of diphenylmethane-4,4'-diisocyanate (MDI) to a mixed base oil consisting of 25.97 parts by mass of low viscosity low evaporation PAO (A1-1), 12.98 parts by mass of medium viscosity PAO (A1-2), and 3.25 parts by mass of ester-based synthetic oil (A2), which were heated to 80°C. Solution β was prepared by adding 5.00 parts by mass of stearylamine, 1.20 parts by mass of cyclohexylamine, and 0.5 parts by mass of dispersant (C1) to a separately prepared mixed base oil consisting of 24.1 parts by mass of low viscosity low evaporation PAO (A1-1), 12.05 parts by mass of medium viscosity PAO (A1-2), and 3.25 parts by mass of ester-based synthetic oil (A2), which were heated to 80°C. Then, while stirring solution β heated to 80°C, solution α heated to 80°C was added, and after stirring for 10 minutes with the stirring blades rotated, 3.0 parts by mass of olefin copolymer (A3) was added, and while continuing to stir, the temperature was raised to 150°C and held for 1 hour to produce urea grease (b1). The urea-based thickener (B1) contained in the obtained urea grease is R in the general formula (b1) above. １ and R ２ However, it is a stearyl group or a cyclohexyl group, R ３This corresponds to a compound in which the diphenylmethylene group is present. The molar ratio of stearylamine and cyclohexylamine used as raw materials (stearylamine / cyclohexylamine) is 6 / 4. (2) Preparation of the grease composition Next, the urea grease (b1), which had been cooled to 100°C by natural cooling, was mixed with each component of the additive (C) other than the dispersant (C1) in the amounts shown in Table 1, and homogenized using a three-roll mill to obtain the grease composition of Example 1.

[0101] (Examples 2-7 and Comparative Examples 1-4) Grease compositions for Examples 2-7 and Comparative Examples 1-4 were prepared in the same manner as in Example 1, except that the components and their contents were changed as shown in Tables 1-3.

[0102] (Example 8) As lithium soap (B2), lithium stearate (product name: S-7000, manufactured by Sakai Chemical Industry Co., Ltd.) was prepared. 12 parts by mass of lithium stearate was added to the entire amount of base oil (A), heated and stirred to 205°C to dissolve, then cooled to 100°C, and each component of additive (C) was added and mixed in the amounts shown in Table 2. Homogenization treatment was performed using a three-roll mill to prepare the grease composition of Example 8.

[0103] (Example 9) As lithium soap (B2), lithium 12-hydroxystearate (product name: S-7000H, manufactured by Sakai Chemical Industry Co., Ltd.) was prepared. Ten parts by mass of lithium 12-hydroxystearate was added to the entire amount of base oil (A), heated and stirred to 205°C to dissolve, then cooled to 100°C, and each component of additive (C) was added in the amounts shown in Table 2 and mixed. Homogenization treatment was performed using a three-roll mill to prepare the grease composition of Example 9.

[0104] [Evaluation of Torque Reduction Performance] 5 g ± 0.2 g of each grease composition from Examples 1-9 and Comparative Examples 1-4 was homogeneously sealed inside the resin cage of NTN Corporation's "Deep Groove Ball Bearing 6306". Next, non-contact rubber seals with lip cuts were attached to both sides of the bearing to create a bearing for torque measurement. Then, the rotational torque (unit: mN·m) at 25°C was measured under the following measurement conditions. The average value over a test period of 20 to 30 minutes was taken as the rotational torque value. The torque reduction performance was evaluated to see how the rotational torque changed in the Examples and Comparative Examples with the same base oil composition. Specifically, the rotational torque of Examples 1-4 was evaluated to see if it decreased from the rotational torque of Comparative Example 1. Similarly, Example 5 was evaluated to see if it decreased from Example 2, Example 6 from Comparative Example 3, and Example 7 from Comparative Example 4. For Examples 8-9, instead of using the Comparative Examples with the same base oil composition, a rotational torque of 40 mN·m or less was considered acceptable. -Measurement conditions- Axial load: 200N Radial load: 0N Rotation speed: 1,000 rpm Test time: 30 minutes Test temperature: Room temperature (25℃)

[0105] The results are shown in Tables 1 to 3.

[0106]

[0107]

[0108]

[0109] Tables 1 to 3 show that the rotational torque of the grease compositions of Examples 1 to 9 is lower than that of the grease compositions of Comparative Examples 1 to 4. From this, it was found that the grease compositions of Examples 1 to 9 are grease compositions that exhibit excellent torque reduction properties through an approach using thickeners.

Claims

1. A grease composition comprising: a base oil (A); and a thickener (B), wherein the thickener (B) is at least one selected from the group consisting of one or more urea-based thickeners (B1) selected from diurea compounds represented by the following general formula (b1), and lithium soap (B2), R １ -NHCONH-R ３ -NHCONH-R ２ (b1) [in the general formula (b1), R １ and R ２ each independently represent a monovalent chain hydrocarbon group or alicyclic hydrocarbon group having 6 to 24 carbon atoms. R １ and R ２ may be the same or different from each other. R ３ represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms.] When the content of chain hydrocarbon groups in R １ and R ２ in the general formula (b1) is X molar equivalent, and the content of alicyclic hydrocarbon groups is Y molar equivalent, the following requirement (1) is satisfied: Requirement (1): an X / Y ratio is 3 / 2 or more; and a Young's modulus of the thickener (B) is 1.4 GPa or less.

2. The grease composition according to claim 1, wherein the lithium soap (B2) is one or more selected from lithium stearate and lithium 12-hydroxystearate.

3. The kinematic viscosity of the base oil (A) at 40°C is 15 mm ２ / s ~ 50mm ２ A grease composition according to any one of claims 1 or 2, wherein the ratio is / s.

4. The grease composition according to any one of claims 1 to 3, wherein the miscible consistency at 25°C is 265 to 295.

5. A grease composition according to any one of claims 1 to 4, used for lubricating hub bearings.

6. A method for adjusting the Young's modulus of the thickener (B) to 1.4 GPa or less by selecting one or more urea-based thickeners (B1) selected from diurea compounds represented by the following general formula (b1), and / or one or more thickeners (B) selected from lithium soap (B2). １ -NHCONH-R ３ -NHCONH-R ２ (b1) [In the above general formula (b1), R １ and R ２ Each of these independently represents a monovalent chain hydrocarbon group or alicyclic hydrocarbon group having 6 to 24 carbon atoms. １ and R ２ They may be the same or they may be different from one another. ３ R represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms. ] In the above general formula (b1) R １ and R ２ In this mixture, when the content of chain hydrocarbon groups is X molar equivalents and the content of alicyclic hydrocarbon groups is Y molar equivalents, the following requirement (1) is met: Requirement (1): The X / Y ratio is 3 / 2 or greater.

7. A method for producing a grease composition, comprising the step of carrying out the preparation method described in claim 6.

Images