Grease composition

Abstract

To provide a grease composition with excellent water resistance.SOLUTION: A grease composition contains a base oil, a thickener, and a metal detergent. The metal detergent contains fatty acid zinc and calcium sulfonate represented by the following formula (1). In the formula (1), R1 and R2 each independently represent an aliphatic hydrocarbon group having 8 to 18 carbon atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a grease composition. [Background technology]

[0002] Vehicles such as automobiles, trucks, and bicycles are used in a variety of environments and may be exposed to, for example, rainwater. If a vehicle is continuously used in such an environment where it comes into contact with water, and a non-water-resistant grease composition is used in the bearings, the grease composition may leak from the bearings.

[0003] Generally, grease compositions used in vehicle wheel bearings are lithium soap or lithium complex soap greases. These greases are subject to frictional heat from the brakes or bearings and are constantly exposed to high temperatures during operation. Furthermore, the grease composition is subjected to shear stress due to the intense agitation generated when the bearing rotates. If the grease composition lacks sufficient shear stability, it may soften. In extreme cases, prolonged use can lead to grease leakage.

[0004] Therefore, in the field of lubricating oils such as grease compositions used under such conditions of exposure to water or heat, further improvement in water resistance or heat resistance is desired, and attempts have been made to improve them by blending techniques of base oils and additives (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-46625 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-247888 Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure has been made in view of the above circumstances, and an object of one embodiment of the present disclosure is to provide a grease composition that has excellent water resistance. [Means for solving the problem]

[0007] As a result of extensive research aimed at solving the above problems, the present inventors have found that water resistance can be improved by including an organic zinc salt and calcium sulfonate having specific structures as metal detergents in a grease composition. That is, the means for solving the above problems include the following embodiments.

[0008] <1> A grease composition comprising a base oil, a thickener, and a metal detergent, wherein the metal detergent comprises a fatty acid zinc salt and calcium sulfonate represented by the following formula (1):

[0009] [ka]

[0010] In formula (1), R1 and R2 each independently represent an aliphatic hydrocarbon group having 8 to 18 carbon atoms.

[0011] <2> The thickener comprises lithium soap. <1> The grease composition according to claim 1.

[0012] <3> The organic zinc salt represented by formula (1) contains a fatty acid zinc salt in which at least one of R1 and R2 represents an isostearyl group. <1> or <2> The grease composition according to claim 1. <4> The organic zinc salt represented by formula (1) includes a fatty acid zinc salt in which at least one of R1 and R2 represents a 2-ethylhexyl group. <1> ~ <3> 1. The grease composition according to claim 1 . <5> The organic zinc salt represented by formula (1) includes a fatty acid zinc salt in which at least one of R1 and R2 represents a neodecyl group. <1> ~ <4> 1. The grease composition according to claim 1 .

[0013] <6> The total content of the organic zinc salt represented by formula (1) and calcium sulfonate is 0.5% by mass to 3.0% by mass relative to the total mass of the grease composition. <1> ~ <5> The grease composition according to any one of the preceding claims. <7> The content of calcium sulfonate is 0.05% by mass to 0.40% by mass based on the total mass of the grease composition. <1> ~ <6> 1. The grease composition according to claim 1 . [Effects of the Invention]

[0014] According to one embodiment of the present disclosure, a grease composition having excellent water resistance is provided. DETAILED DESCRIPTION OF THE INVENTION

[0015] Specific embodiments of the grease composition according to the present disclosure will be described in detail below, however, the grease composition according to the present disclosure is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the object of the present disclosure.

[0016] In the present disclosure, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the present disclosure, the upper or lower limit of a numerical range described in stages may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in the present disclosure, the upper or lower limit of a numerical range described in stages may be replaced with a value shown in the examples. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In the present disclosure, "mass %" and "weight %" are synonymous. In the present disclosure, when there are multiple substances corresponding to each component, the amount of each component means the total amount of the multiple substances unless otherwise specified. In this disclosure, "JIS" is used as an abbreviation for Japanese Industrial Standards.

[0017] [Grease composition] The grease composition according to the present disclosure contains a base oil, a thickener, and a metal detergent, and the metal detergent contains a fatty acid zinc salt and calcium sulfonate represented by the following formula (1): [ka]

[0018] In formula (1), R1 and R2 each independently represent an aliphatic hydrocarbon group having 8 to 18 carbon atoms.

[0019] Hereinafter, the fatty acid zinc salts and calcium sulfonates represented by formula (1) are also collectively referred to as "specific metal detergents," and the organic acid zinc salts represented by formula (1) are also referred to as "specific fatty acid zinc salts."

[0020] The grease composition according to the present disclosure is a grease composition containing a base oil, a thickener, and a specific metal detergent, and by selectively containing a specific fatty acid zinc salt and calcium sulfonate as the metal detergent, the grease composition exhibits excellent water resistance. The reason for this is not clear, but is presumed to be as follows.

[0021] Water mixed into a grease composition acts to form micelles with a thickener such as lithium soap. As a result, the thickener fiber structure in the grease composition collapses, causing consistency softening. Consistency softening in a grease composition can cause grease leakage from bearings, for example. In contrast, the grease composition according to the present disclosure contains a base oil, a thickener, and a metal detergent. The metal detergent contains a fatty acid zinc salt (specific fatty acid zinc salt) represented by formula (1) and calcium sulfonate. The specific fatty acid zinc salt can finely disperse water mixed into the grease composition and form micelles. It is believed that by forming micelles preferentially over the thickener, it suppresses the destruction of the thickener fiber structure due to water contamination. Furthermore, the inclusion of calcium sulfonate in the metal detergent leads to stronger formation of micelles between water and the specific fatty acid zinc salt, more effectively suppressing consistency softening, thereby demonstrating excellent water resistance.

[0022] <Base oil> The grease composition according to the present disclosure comprises a base oil. The base oil is not particularly limited and may be, for example, a mineral oil, a synthetic oil, or a mixture thereof. The base oil may be used alone or in combination of two or more. In one embodiment, the base oil is preferably a mineral oil.

[0023] Examples of mineral oils include those obtained by refining lubricating oil fractions of crude oil using an appropriate combination of refining methods such as solvent refining, hydrorefining, hydrocracking refining, hydrodewaxing, etc. Examples of mineral oils include paraffinic mineral oils that are highly refined by subjecting hydrorefined oils, catalytic isomerized oils, etc. to treatments such as solvent dewaxing or hydrodewaxing.

[0024] Examples of synthetic oils include ether-based synthetic oils such as alkyldiphenyl ether; ester-based synthetic oils such as diesters, polyol esters, and complex-type polyol esters; synthetic hydrocarbon oils such as polyalphaolefins; and alkylnaphthalene-based synthetic oils.

[0025] The kinematic viscosity of the base oil at 40°C is 10mm 2 / s~500mm 2 / s is preferred, 30 mm 2 / s~300mm 2 / s is more preferable, 50 mm 2 / s~300mm 2 / s is more preferable. 2 / s~500mm 2 / s, the grease composition is particularly suitable for use in wheel bearings.

[0026] In the present disclosure, the kinematic viscosity of the base oil at 40°C refers to a value measured according to JIS K 2283:2000 "Kinematic Viscosity Testing Method."

[0027] The content of the base oil is not particularly limited and can be adjusted appropriately within the range of 77% by mass to 97% by mass relative to the total mass of the grease composition.

[0028] <Thickener> The grease composition according to the present disclosure contains a thickener. There are no limitations on the thickener as long as it is applicable to grease compositions, and it can be appropriately selected taking into consideration the desired physical properties of the grease composition, the environment in which the grease composition will be used, etc. Examples of thickeners include lithium soap, lithium complex soap, calcium soap, calcium complex soap, aluminum complex soap, diurea compounds, and sodium terephthalamate.

[0029] Among these, the thickener preferably contains at least one compound selected from the group consisting of lithium soap and lithium complex soap, and more preferably lithium soap.

[0030] Lithium soap is a lithium salt of a higher fatty acid. Lithium complex soap is a complex soap that combines a lithium salt of a higher fatty acid and a lithium salt of a dicarboxylic acid.

[0031] From the viewpoint of heat resistance, the lithium soap is preferably a lithium salt of a monocarboxylic acid having 12 to 24 carbon atoms. From the viewpoint of heat resistance, the lithium complex soap is preferably a complex of a lithium salt of a monocarboxylic acid having 12 to 24 carbon atoms and a lithium salt of a dicarboxylic acid having 2 to 12 carbon atoms. Suitable monocarboxylic acids include stearic acid, 12-hydroxystearic acid, etc. Suitable dicarboxylic acids include succinic acid, malonic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, etc.

[0032] As the thickener, lithium soap is more preferred in terms of availability and ease of handling.

[0033] The grease composition according to the present disclosure may contain only one type of thickener, or may contain two or more types of thickener.

[0034] The content of the thickener can be adjusted appropriately according to the desired worked penetration, and is preferably 5 to 20% by mass, more preferably 5 to 15% by mass, relative to the total mass of the grease composition.

[0035] <Metal cleaning agents> The grease composition according to the present disclosure contains a metal detergent, and the metal detergent includes a fatty acid zinc salt and calcium sulfonate (i.e., a specific metal detergent) represented by the following formula (1):

[0036] [ka]

[0037] In formula (1), R1 and R2 each independently represent an aliphatic hydrocarbon group having 8 to 18 carbon atoms.

[0038] (organic zinc salt represented by formula (1)) One of the compounds constituting the specific metal detergent is a fatty acid zinc salt (specific fatty acid zinc salt) represented by formula (1).

[0039] The aliphatic hydrocarbon group having 8 to 18 carbon atoms represented by R1 or R2 is a saturated or unsaturated aliphatic hydrocarbon group having 8 to 18 carbon atoms, and may be any of a straight-chain, branched-chain, and cyclic aliphatic hydrocarbon group. The aliphatic hydrocarbon group having 8 to 18 carbon atoms represented by R1 or R2 is preferably a branched-chain aliphatic hydrocarbon group having 8 to 18 carbon atoms. The branched-chain aliphatic hydrocarbon group may be a saturated group or an unsaturated group, but is preferably a saturated group.

[0040] The aliphatic hydrocarbon group having 8 to 18 carbon atoms represented by R1 or R2 is preferably a saturated branched aliphatic hydrocarbon group having 8 to 18 carbon atoms, and examples thereof include an isostearyl group, a 2-ethylhexyl group, and a neodecyl group.

[0041] One preferred embodiment of the specific fatty acid zinc is a fatty acid zinc in which at least one of R1 and R2 represents an isostearyl group (hereinafter also referred to as specific fatty acid zinc A). When at least one of R1 and R2 is an isostearyl group, only one of R1 and R2 may be an isostearyl group, or both R1 and R2 may be isostearyl groups.

[0042] Another preferred embodiment of the specific fatty acid zinc is a fatty acid zinc in which at least one of R1 and R2 represents a 2-ethylhexyl group (hereinafter also referred to as specific fatty acid zinc B). When at least one of R1 and R2 is a 2-ethylhexyl group, only one of R1 and R2 may be a 2-ethylhexyl group, or both R1 and R2 may be 2-ethylhexyl groups. Specific fatty acid zinc B may also be a fatty acid zinc corresponding to specific fatty acid zinc A (i.e., a fatty acid zinc in which one of R1 and R2 is an isostearyl group and the other is a 2-ethylhexyl group). Specific fatty acid zinc B may also be a fatty acid zinc having a different structure from specific fatty acid zinc A (i.e., a fatty acid zinc in which one of R1 and R2 is a 2-ethylhexyl group and the other is a branched-chain aliphatic hydrocarbon group other than an isostearyl group).

[0043] Another preferred embodiment of the specific fatty acid zinc is a fatty acid zinc in which at least one of R1 and R2 represents a neodecyl group (hereinafter also referred to as specific fatty acid zinc C). When at least one of R1 and R2 is a neodecyl group, only one of R1 and R2 may be a neodecyl group, or both R1 and R2 may be neodecyl groups. The specific fatty acid zinc C may be a fatty acid zinc corresponding to the specific fatty acid zinc A (i.e., a fatty acid zinc in which one of R1 and R2 is an isostearyl group and the other is a neodecyl group). The specific fatty acid zinc C may be a fatty acid zinc corresponding to the specific fatty acid zinc B (i.e., a fatty acid zinc in which one of R1 and R2 is a neodecyl group and the other is a 2-ethylhexyl group). The specific fatty acid zinc C may be a fatty acid zinc having a structure different from that of the specific fatty acid zinc A and the specific fatty acid zinc B (i.e., a fatty acid zinc in which one of R1 and R2 is a neodecyl group and the other is a branched-chain aliphatic hydrocarbon group other than an isostearyl group or a 2-ethylhexyl group).

[0044] When the specific fatty acid zinc salt contains two or more selected from specific fatty acid zinc salt A, specific fatty acid zinc salt B, and specific fatty acid zinc salt C, it is preferable that the specific fatty acid zinc salt corresponds to a mixture of two or more selected from zinc isostearate, zinc 2-ethylhexanoate, and zinc neodecanoate.

[0045] From the viewpoint of water resistance, the total content of the specific fatty acid zinc salts is preferably 0.5% by mass to 3.0% by mass, and more preferably 1.0% by mass to 2.0% by mass, relative to the total mass of the grease composition.

[0046] (Calcium sulfonate) One of the compounds constituting the specific metal detergent is calcium sulfonate. The calcium sulfonate is not particularly limited, and examples thereof include calcium salts of alkyl aromatic sulfonates such as calcium salts of alkylbenzenesulfonates and calcium salts of alkylnaphthalenesulfonates.

[0047] From the viewpoint of water resistance, the content of calcium sulfonate is preferably 0.01 to 0.5 mass %, more preferably 0.01 to 0.4 mass %, and even more preferably 0.05 to 0.4 mass %, relative to the total mass of the grease composition.

[0048] From the viewpoint of water resistance, the total content of the specific metal detergents (i.e., specific fatty acid zinc salts and calcium sulfonate) is preferably 0.5 to 3.0 mass %, more preferably 1.0 to 2.5 mass %, and even more preferably 1.2 to 2.0 mass %, relative to the total mass of the grease composition.

[0049] In the specific metal detergent, the content ratio (X:Y) of the specific fatty acid zinc salt (X) to the calcium sulfonate (Y) is preferably 4:1 to 20:1 by mass, more preferably 5:1 to 18:1, and even more preferably 6:1 to 15:1, from the viewpoint of water resistance.

[0050] The grease composition according to the present disclosure may contain metal detergents other than the specific metal detergent (e.g., calcium phenate, calcium salicylate) within the range in which the effects of the present disclosure can be obtained, but from the viewpoint of improving water resistance, it is preferable that the grease composition contain only the specific metal detergent as the metal detergent.

[0051] <Other additives> The grease composition according to the present disclosure may contain other additives in addition to the base oil, thickener, and metal detergent described above, as needed. Examples of other additives that may be included include antioxidants, corrosion inhibitors, rust inhibitors, and extreme pressure agents. These other additives may be used singly or in combination of two or more.

[0052] Examples of antioxidants include alkylphenols such as 2,6-di-tert-butyl-p-cresol, bisphenols such as 4,4'-methylenebis-(2,6-di-t-butylphenol), phenolic compounds such as n-octadecyl-3-(4'-hydroxy-3',5'-di-t-butylphenol) propionate, aromatic amine compounds such as naphthylamines and dialkyldiphenylamines, and zinc thiophosphate compounds.

[0053] Examples of corrosion inhibitors include benzotriazole and benzimidazole.

[0054] Examples of the rust inhibitor include sulfonic acid metal salt compounds and sorbitan compounds.

[0055] Examples of extreme pressure agents include sulfurized olefins, sulfurized fats and oils, sulfurized esters, and polysulfides.

[0056] ~Properties of grease composition~ <Worked penetration> The worked penetration of the grease composition is preferably 205-310, and more preferably 220-295. The worked penetration is a value measured based on JIS K 2220:2013.

[0057] ~Water resistance of grease composition~ The water resistance of the grease composition according to the present disclosure is evaluated in accordance with a water-containing roll stability test (in accordance with ASTM D1831) and water washout resistance (79°C) (JIS K 2220:2013).

[0058] The grease composition according to the present disclosure preferably has a worked penetration change of 90 or less, more preferably 85 or less, and even more preferably 80 or less, in a water-containing roll stability test.

[0059] The grease composition according to the present disclosure preferably has a water wash resistance (79°C) value (i.e., the amount of loss of the sample) of 8 or less, more preferably 7 or less, and even more preferably 6 or less.

[0060] The grease composition according to the present disclosure preferably has both a water-containing roll stability test and water wash resistance (79°C) within the above ranges.

[0061] ~Method for preparing grease composition~ The method for preparing the grease composition according to the present disclosure is not particularly limited, and the grease composition can be prepared by a conventionally known method. For example, the grease composition according to the present disclosure can be prepared by appropriately mixing other additives as needed in addition to the base oil, thickener, and metal detergent.

[0062] ~Target of use of grease composition~ The grease composition according to the present disclosure can be applied to bearings, etc. Since the grease composition according to the present disclosure has excellent water resistance, it can be suitably applied to, for example, wheel bearings of vehicles. [Example]

[0063] The grease composition according to the present disclosure will be specifically described below using examples, but the grease composition according to the present disclosure is not limited to these examples.

[0064] Details of each component contained in the grease composition are as follows:

[0065] <Base oil> Base oil: Solvent refined mineral oil (40℃ kinematic viscosity: 175mm 2 / s)

[0066] <Thickener> · Thickener (lithium soap): Using the manufacturing procedure below, the thickener raw materials were mixed with the base oil, and the raw materials were reacted in the base oil to synthesize the thickener.

[0067] ~Manufacturing procedure (lithium soap)~ The base oil and 12-hydroxystearic acid as a thickener raw material were placed in a heat-resistant container and heated to approximately 90°C while stirring, after which an aqueous lithium hydroxide solution was added and a saponification reaction was carried out for approximately 60 minutes.Then, the mixture was heated to 200°C while stirring to dissolve the fatty acid lithium salt, and then rapidly cooled to obtain a lithium soap.

[0068] <Metal Detergent A (Specific Fatty Acid Zinc)> Specific fatty acid zinc A1 (specific fatty acid zinc prepared as follows) Specific fatty acid zinc A2 (specific fatty acid zinc prepared as follows) Specific fatty acid zinc A3 (specific fatty acid zinc prepared as follows)

[0069] Metal detergent A is a mixture of specific fatty acid zinc salts A1, A2 or A3 (specific fatty acid zinc salts) and mineral oil (kinematic viscosity at 40°C: 10mm 2 The mineral oil was used in the form of a mixture with zinc salts (Zinc salts of zinc isostearate, zinc neodecanoate, and zinc 2-ethylhexanoate). Table 1 shows the compositions of the specific zinc fatty acids A1, A2, and A3 contained in the mineral oil. The zinc fatty acids used as zinc fatty acids A1, A2, and A3 were obtained by simultaneously reacting the starting fatty acids with a zinc salt precursor. In Table 1, the content (mass%) of zinc isostearate, zinc neodecanoate, and zinc 2-ethylhexanoate indicates the content (mass%) corresponding to the converted amount of each zinc fatty acid in the mixture.

[0070] [Table 1]

[0071] Details of the preparation of the fatty acid zinc salts used as specific fatty acid zinc salts A1, A2 and A3 are as follows.

[0072] -Preparation of specific fatty acid zinc salts A1, A2 and A3- For the specific fatty acid zinc A1, fatty acid zinc was obtained by reacting 2-ethylhexanoic acid, neodecanoic acid, isostearic acid, and a zinc salt precursor all at once so that the content in the mineral oil was 11% by mass in terms of zinc 2-ethylhexanoate, 10% by mass in terms of zinc neodecanoate, and 16% by mass in terms of zinc isostearate. Specific fatty acid zinc salts A2 and A3 were prepared in the same manner as specific fatty acid zinc salt A1, except that the blending ratios of 2-ethylhexanoic acid, neodecanoic acid, and isostearic acid were changed so that the respective contents of zinc isostearate, zinc neodecanoate, and zinc 2-ethylhexanoate were as shown in Table 1. That is, the specific fatty acid zinc salts A1, A2, and A3 are mixtures of fatty acid zinc salts in which both R1 and R2 in formula (1) are 2-ethylhexyl groups, fatty acid zinc salts in which both R1 and R2 are neodecyl groups, fatty acid zinc salts in which both R1 and R2 are isostearyl groups, fatty acid zinc salts in which one of R1 and R2 is a 2-ethylhexyl group and the other is a neodecyl group or an isostearyl group, and fatty acid zinc salts in which one of R1 and R2 is a neodecyl group and the other is an isostearyl group.

[0073] <Metal Detergent B (Calcium Sulfonate)> Calcium sulfonate (product name: LUBRIZOL 74W, manufactured by Lubrizol Japan, Inc.)

[0074] (Other additives) Other additives include the following three components (total added amount: 1.03 mass %). 2,6-di-tert-butyl-4-methylphenol 0.5% by mass Phenolic antioxidant (product name: Irganox L57, manufactured by BASF) ...0.5% by mass Corrosion inhibitor (product name: Chiolite B-1001, manufactured by Chiyoda Chemical Co., Ltd.) ...0.03% by mass

[0075] [Examples 1 to 6, Comparative Examples 1 to 10] Each of the grease compositions of the Examples and Comparative Examples was prepared by mixing the components constituting the grease composition so as to obtain the composition shown in the composition column of Tables 2 and 3. After the grease composition was prepared so as to contain the predetermined amounts of each component, it was subjected to a milling process to uniformly disperse the thickener in the grease composition to obtain the final composition. In the composition column of the table, "-" means that the component in question was not blended.

[0076] [Measurement and Evaluation] The following measurements and evaluations were carried out on each of the obtained grease compositions, and the results are shown in Tables 2 and 3.

[0077] (1) Worked consistency The worked penetration of each grease composition was measured in accordance with JIS K 2220:2013.

[0078] (2) Washing water resistance (79℃) For each grease composition, water resistance after washing (79°C) was measured in accordance with JIS K 2220:2013. The measurement was carried out twice for each grease composition, and the average of the results (sample loss: mass%) was taken as the water resistance after washing. The evaluation was based on the following criteria. -Judgment criteria- A: The loss amount of the sample is 7% by mass or less. B: The loss amount of the sample is greater than 7% by mass.

[0079] (3) Stability of water-containing roll Each grease composition was subjected to a water-containing roll stability test in accordance with ASTM D1831 (in accordance with the present invention) and evaluated according to the following criteria. -Test conditions- The water content of the sample was 10% by mass (45 g of grease composition, 5 g of water), the test temperature was 80°C, the test time was 2 hours, and the roll rotation speed was 165 rpm (revolutions per minute). The worked penetration of the grease composition after the test was measured. The difference in worked penetration calculated by subtracting the worked penetration value before the test measured in (1) above from the worked penetration value of the grease composition after the test was taken as the change in consistency. -Judgment criteria- A: The change in consistency is 90 or less. B: The change in consistency is greater than 90.

[0080] Regarding the evaluation of water resistance, if the evaluation results for both (2) water wash resistance (79°C) and (3) water-containing roll stability were rated A, the grease composition was judged to have superior water resistance.

[0081] [Table 2]

[0082] [Table 3]

[0083] As shown in Tables 2 and 3, the grease compositions of Examples 1 to 6, which contained a base oil, a thickener, and a specific metal detergent (i.e., a specific fatty acid zinc salt and calcium sulfonate), were rated A for both the water-containing roll stability and the water-washing resistance, and were therefore superior in water resistance compared to Comparative Examples 1 to 10, which were rated B for both or either of the water-containing roll stability and the water-washing resistance.

[0084] From the above, it can be seen that the grease composition according to the present disclosure has excellent water resistance.

Claims

1. A grease composition comprising a base oil, a thickener, and a metal detergent, wherein the metal detergent contains a fatty acid zinc salt and calcium sulfonate represented by the following formula (1): the thickener comprises lithium soap; The grease composition comprises an organic zinc salt represented by the formula (1) comprising a fatty acid zinc salt in which at least one of R 1 and R 2 represents an isostearyl group, a fatty acid zinc salt in which at least one of R 1 and R 2 represents a 2-ethylhexyl group, and a fatty acid zinc salt in which at least one of R 1 and R 2 represents a neodecyl group. 【Chemistry 1】 In formula (1), R １ and R ２ each independently represents an aliphatic hydrocarbon group having 8 to 18 carbon atoms.

2. A grease composition comprising a base oil, a thickener, and a metal detergent, wherein the metal detergent comprises a fatty acid zinc salt and calcium sulfonate represented by the following formula (1): the thickener comprises lithium soap; A grease composition, wherein the organic acid zinc salt represented by the formula (1) comprises a fatty acid zinc salt in which at least one of R 1 and R 2 represents an isostearyl group. 【Chemistry 2】 In formula (1), R 1 and R 2 each independently represent an aliphatic hydrocarbon group having 8 to 18 carbon atoms.

3. A grease composition comprising a base oil, a thickener, and a metal detergent, wherein the metal detergent comprises a fatty acid zinc salt and calcium sulfonate represented by the following formula (1): the thickener comprises lithium soap; A grease composition, wherein the organic acid zinc salt represented by the formula (1) comprises a fatty acid zinc salt in which at least one of R 1 and R 2 represents a neodecyl group. 【Transformation 3】 In formula (1), R 1 and R 2 each independently represent an aliphatic hydrocarbon group having 8 to 18 carbon atoms.

4. 4. The grease composition according to claim 1, wherein the total content of the organic zinc salt represented by formula (1) and the calcium sulfonate is 0.5% by mass to 3.0% by mass, relative to the total mass of the grease composition.

5. 5. The grease composition according to claim 1, wherein the content of the calcium sulfonate is 0.05% by mass to 0.40% by mass, based on the total mass of the grease composition.

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