Lubricating grease composition

Abstract

To provide a lubricating grease composition that has high static frictional force and excellent wear resistance in sliding between metal members.SOLUTION: A lubricating grease composition comprises a base oil and a thickener, wherein the base oil comprises at least one perfluoropolyether, and the thickener comprises 5 mass% or more to 100 mass% or less of calcium carbonate, 0 mass% or more to 95 mass% or less of melamine cyanurate, and 0 mass% or more to 20 mass% or less of polytetrafluoroethylene for the total mass of the thickener.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Power transmission components such as gears and clutches, and feed screws such as sliding screws and ball screws require a static function to prevent positional changes when stationary, and therefore require grease with high static friction. This static function utilizes sliding contact, which causes friction and wear on the sliding components. Therefore, to extend the life of machine components, greases must also have excellent wear resistance.

[0003] For example, Patent Document 1 discloses that a grease composition having excellent static properties (high frictional force) can be obtained by using melamine cyanurate and polytetrafluoroethylene as a solid lubricant, and Patent Document 2 discloses that a grease composition having excellent static properties (high frictional force) can be obtained by using calcium carbonate as a solid lubricant. Patent Document 3 also discloses a grease composition containing perfluoropolyether oil as a base oil and using melamine cyanurate as a thickener.

[0004] However, while all of these patent documents evaluate the lubrication properties when resin members slide against each other or when a resin member slides against a metal member, they do not mention the lubrication properties when metal members slide against each other. Therefore, there is a need for the development of a grease composition that exhibits sufficient lubrication performance even when used in sliding between metal members. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-13351 [Patent Document 2] International Publication No. 2018 / 030090 [Patent Document 3] Japanese Patent Application Publication No. 2017-20052 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention provides a lubricating grease composition that has high static friction force and excellent wear resistance when metal members slide against each other. [Means for solving the problem]

[0007] A lubricating grease composition according to an embodiment of the present invention contains a base oil and a thickener, wherein the base oil contains at least one perfluoropolyether, and the thickener contains, relative to the total mass of the thickener, 5% by mass to 100% by mass of calcium carbonate, 0% by mass to 95% by mass of melamine cyanurate, and 0% by mass to 20% by mass of polytetrafluoroethylene.

[0008] In one embodiment of the present invention, the average particle size of calcium carbonate is 30 μm or less.

[0009] In one embodiment of the present invention, the thickener contains more than 10 mass % and not more than 100 mass % of calcium carbonate, based on the total mass of the thickener.

[0010] In one embodiment of the present invention, the content of polytetrafluoroethylene relative to the total mass of the thickener is 0 mass %.

[0011] In one embodiment of the present invention, the average particle size of calcium carbonate is 10 μm or less, and the content of calcium carbonate is 100 mass% relative to the total mass of the thickener, or the content of melamine cyanurate having an average particle size of 10 μm or less is more than 0 mass% and less than 90 mass%.

[0012] In one embodiment of the present invention, the lubricating grease composition is used in sliding parts between metal members. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a lubricating grease composition that has high static friction force when metal members slide against each other and has excellent wear resistance. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the present invention will be described below. The lubricating grease composition according to this embodiment contains a base oil as a main component and a thickener. The base oil contains at least one perfluoropolyether, and the thickener contains 5% by mass to 100% by mass of calcium carbonate. The thickener may further contain 0% by mass to 95% by mass of melamine cyanurate or 0% by mass to 20% by mass of polytetrafluoroethylene. By blending calcium carbonate alone or in addition to calcium carbonate with a lubricating grease composition containing a perfluoropolyether as a base oil, and a thickener that may further contain a predetermined amount of melamine cyanurate and a predetermined amount of polytetrafluoroethylene, the lubricating grease composition is endowed with high static performance and excellent friction characteristics for sliding between metal members. This allows for the production of a lubricating grease composition that exhibits high static friction and excellent wear resistance when sliding between metal members. Each component of the lubricating grease composition according to this embodiment will be described in detail below.

[0015] <Base oil> In this embodiment, the base oil contains at least one perfluoropolyether (PFPE). The perfluoropolyether may be linear or branched and is not particularly limited, but for example, a compound represented by the following formula (1) is preferably used.

[0016] [ka]

[0017] In formula (1), the CFO, CFO, and CFO groups are groups randomly bonded in the main chain, and Rf is a perfluoro lower alkyl group having 1 to 5 carbon atoms, preferably 1 to 3, such as a perfluoromethyl group, a perfluoroethyl group, or a perfluoropropyl group. In addition, x + y + z = 3 to 200, and at least one of x, y, and z may be 0. As the compound represented by formula (1), for example, perfluoropolyethers represented by the following formulas (2) to (5) can be used.

[0018] [ka]

[0019] In formula (2), Rf is the same as defined in formula (1), and a is 2 to 200. The compound represented by formula (1) can be produced by completely fluorinating a precursor produced by photooxidative polymerization of hexafluoropropylene, or by anionic polymerization of hexafluoropropylene in the presence of a cesium fluoride catalyst and treating the resulting acid fluoride compound having a terminal CF(CF3)COF group with fluorine gas.

[0020] [ka]

[0021] In formula (3), Rf is the same as defined in formula (1), b+c=3 to 200, and b:c=10:90 to 90:10. The compound represented by formula (3) can be produced by completely fluorinating a precursor produced by photooxidative polymerization of hexafluoropropene.

[0022] [ka]

[0023] In formula (4), Rf is the same as defined in formula (1), d+e = 3 to 200, d:e = 10:90 to 90:10, and preferably d / e > 1. The compound represented by formula (4) can be produced by completely fluorinating a precursor produced by photooxidative polymerization of tetrafluoroethylene.

[0024] [ka]

[0025] In formula (5), f = 2 to 100. The compound represented by formula (5) is a fluorine-containing polyether (CH2CF2CF2O) obtained by anionic polymerization of 2,2,3,3-tetrafluorooxetane in the presence of a cesium fluoride catalyst. n can be produced by treating with fluorine gas under ultraviolet irradiation at 160 to 300°C.

[0026] The perfluoropolyether as the base oil may be used alone or in combination of two or more kinds. The kinematic viscosity (40°C) of the perfluoropolyether is not particularly limited, but is preferably 10 to 2000 mm 2 / sec, and 10 to 1500 mm 2 / sec. Commercially available perfluoropolyethers include, for example, "FOMBLIM (registered trademark) M03" (kinematic viscosity at 40°C: 17 mmHg) manufactured by Solvay Specialty Polymers Japan Ltd. 2 / sec), "FOMBLIM (registered trademark) M15" (40°C kinematic viscosity: 85 mm 2 / s), NOK Kluber "BARRIERTA J60 FLUID" (40℃ kinematic viscosity: 60mm 2 / second) can be used.

[0027] The content of the base oil in the lubricating grease composition is preferably 50% by mass or more and 95% by mass or less, more preferably 60% by mass or more and 90% by mass or less, and even more preferably 70% by mass or more and 85% by mass or less, based on the total mass of the lubricating grease composition.

[0028] <Thickener> In this embodiment, the thickener contains calcium carbonate in an amount of 5% by mass to 100% by mass, preferably more than 10% by mass to 100% by mass, melamine cyanurate in an amount of 0% by mass to 95% by mass, and polytetrafluoroethylene in an amount of 0% by mass to 20% by mass, based on the total mass of the thickener. Specifically, the thickener is preferably calcium carbonate, a mixture of calcium carbonate and melamine cyanurate, or a mixture of calcium carbonate and polytetrafluoroethylene. In particular, by containing calcium carbonate in an amount of more than 10% by mass to 100% by mass, based on the total mass of the thickener, the static friction force and wear resistance can be further improved. Alternatively, the calcium carbonate content may be 100% by mass based on the total mass of the thickener, thereby providing a lubricating grease composition with significantly improved static friction force and wear resistance.

[0029] The content of calcium carbonate in the lubricating grease composition is preferably 2% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less, based on the total mass of the lubricating grease composition. The average particle size (primary particle size) of calcium carbonate is preferably 0.05 μm or more and 30 μm or less, more preferably 0.06 μm or more and 20 μm or less, and even more preferably 0.08 μm or more and 10 μm or less. The static friction force can be particularly improved by using calcium carbonate with an average particle size of 10 μm or less.

[0030] Examples of commercially available calcium carbonate products that can be used include "Hakuenka PZ" (primary particle size: 0.08 μm) manufactured by Shiraishi Calcium Co., Ltd., "Escalon #3500" (average particle size: 1.0 μm) manufactured by Sankyo Flour Milling Co., Ltd., "Escalon Grade 1" (average particle size: 20 μm) manufactured by Sankyo Flour Milling Co., Ltd., and "SFT-2000" (average particle size: 30 μm) manufactured by Sankyo Flour Milling Co., Ltd.

[0031] When the thickener further contains melamine cyanurate, the content of melamine cyanurate is preferably more than 0% by mass and not more than 95% by mass, more preferably more than 0% by mass and less than 90% by mass, and even more preferably more than 0% by mass and not more than 80% by mass, relative to the total mass of the thickener. By making the content of melamine cyanurate less than 90% by mass relative to the total mass of the thickener, it is possible to further improve static friction force and abrasion resistance.

[0032] The average particle size of the melamine cyanurate is preferably 0.1 μm or more and 30 μm or less, more preferably 0.5 μm or more and 20 μm or less, and even more preferably 1.0 μm or more and 10 μm or less. In particular, by using melamine cyanurate with an average particle size of 10 μm or less, static friction force can be improved.

[0033] The melamine cyanurate used is not particularly limited, and known melamine cyanurates can be used. Specifically, melamine cyanurates described in JP-B-45-5595, JP-B-61-34430, JP-A-05-310716, JP-A-07-224049, etc. can be suitably used. In addition, commercially available products that can be used include, for example, "MCA-1" manufactured by Mitsubishi Chemical Corporation, "MC-860," "MC-4000," "MC-4500," and "MC-6000" manufactured by Nissan Chemical Industries, Ltd., and "Melapur (registered trademark) MC 15" manufactured by BASF.

[0034] When the thickener further contains polytetrafluoroethylene (PTFE), the polytetrafluoroethylene content is preferably more than 0% by mass and not more than 10% by mass, more preferably more than 0% by mass and not more than 5% by mass, relative to the total mass of the thickener. Having a polytetrafluoroethylene content of 10% by mass or less relative to the total mass of the thickener can impart high static friction and excellent wear resistance to the lubricating grease composition. On the other hand, in a lubricating grease composition containing perfluoropolyether as the base oil and calcium carbonate as the thickener, it is preferable that the polytetrafluoroethylene content relative to the total mass of the thickener is 0% by mass, i.e., the thickener does not contain the conventionally used polytetrafluoroethylene, thereby further improving static friction and wear resistance.

[0035] The average particle size of the polytetrafluoroethylene is preferably 0.1 μm or more and 50.0 μm or less, and more preferably 0.1 μm or more and 10.0 μm or less. The polytetrafluoroethylene used is not particularly limited, and commercially available products such as "Dyneon (registered trademark) TF9207Z" manufactured by 3M Japan and "Algoflon (registered trademark) DF PTFE" manufactured by Solvay Specialty Polymers Japan can be used.

[0036] The content of the thickener in the lubricating grease composition is preferably 5% by weight or more and 50% by weight or less, more preferably 10% by weight or more and 40% by weight or less, and even more preferably 15% by weight or more and 30% by weight or less, based on the total weight of the lubricating grease composition.

[0037] In this embodiment, the lubricating grease composition may contain other additives to the extent that the effects of the lubricating grease composition are not affected. Examples of such additives include known antioxidants, extreme pressure agents, rust inhibitors, corrosion inhibitors, viscosity index improvers, and oiliness agents. These additives may be used alone or in combination of two or more. The type, amount, and other factors can be determined as desired depending on the intended use.

[0038] Examples of the antioxidant include phenolic antioxidants such as 2,6-di-t-butyl-4-methylphenol and 4,4'-methylenebis(2,6-di-t-butylphenol), and amine antioxidants such as alkyldiphenylamines, phenothiazine, alkylated phenyl-α-naphthylamines, phenithiazine, and alkylated phenothiazine.

[0039] Examples of extreme pressure agents include phosphorus-based compounds such as acid phosphate esters, phosphites, and acid phosphate amine salts; sulfur-based compounds such as sulfides and disulfides; chlorine-based compounds such as chlorinated paraffin and chlorinated diphenyl; and metal organic compounds such as zinc dialkyldithiophosphate (ZnDTP) and molybdenum dialkyldithiocarbamate (MoDTP).

[0040] Examples of the rust inhibitor include fatty acids, fatty acid soaps, alkyl sulfonates, fatty acid amines, oxidized paraffins, and polyoxyethylene alkyl ethers.

[0041] Examples of corrosion inhibitors include benzotriazole, benzimidazole, and thiadiazole.

[0042] Examples of viscosity index improvers include polymethacrylate, ethylene-propylene copolymer, polyisobutylene, polyalkylstyrene, and hydrogenated styrene-isoprene copolymer.

[0043] Examples of oily agents include fatty acids, higher alcohols, polyhydric alcohols, polyhydric alcohol esters, aliphatic esters, aliphatic amines, and fatty acid monoglycerides.

[0044] The lubricating grease composition according to this embodiment can be produced by mixing the above-mentioned base oil, thickener, and optionally other components using a conventional mixing means, which is not particularly limited, but for example, a three-roll mill or a high-pressure homogenizer can be suitably used.

[0045] The lubricating grease composition according to this embodiment has high static friction and low wear depth during sliding between metal members, making it suitable for use in sliding portions between metal members, and therefore exhibits excellent lubricating performance during sliding between metal members.

[0046] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention. [Example]

[0047] Examples of the present invention will be described below, but the present invention is not limited to these examples as long as they do not deviate from the spirit of the present invention. Furthermore, unless otherwise specified, room temperature is within the range of 20°C ± 5°C.

[0048] Example 1 Perfluoropolyether A (40°C kinematic viscosity: 17mm 2 / s, product name "FOMBLIM (registered trademark) M03", manufactured by Solvay Specialty Polymers Japan Ltd.) 40 parts by mass and perfluoropolyether B (kinematic viscosity at 40°C: 85 mm 2A lubricating grease composition was prepared by blending 20 parts by mass of calcium carbonate A (average particle size: 1.0 μm, product name "Escalon #3500", manufactured by Sankyo Flour Milling Co., Ltd.) as a thickener with a base oil containing 40 parts by mass of PEG-100 / s (product name "FOMBLIM (registered trademark) M15", manufactured by Solvay Specialty Polymers Japan Ltd.) and stirring the mixture, followed by processing in a three-roll mill.

[0049] <Measurement and evaluation of abrasion resistance> Using an SRV tester, the obtained lubricating grease composition (sample oil) was applied to a test piece, and a sliding test was performed under the following test conditions to measure the metal-to-metal wear depth. If the wear depth after the test was less than 2.0 μm, it was rated as "Good." If the wear depth was 2.0 μm or more but not more than 3.0 μm, it was rated as "Average." If the wear depth exceeded 3.0 μm or the test automatically stopped before completion and measurement was impossible, it was rated as "Poor." If it was rated as "Average" or better, it was rated as excellent wear resistance. The evaluation results are shown in Table 1.

[0050] Upper test piece: SUJ2 metal ball (diameter 10 mm) Lower test piece: SUJ2 metal disc Load: 100N Amount of sample oil applied: 0.07g Frequency: 100Hz Amplitude: 0.5mm Temperature: room temperature Time: 1 hour

[0051] <Measurement and evaluation of static friction force> Using a reciprocating tester, the obtained lubricating grease composition (sample oil) was applied to a test piece, and a sliding test was performed under the following test conditions to measure the static friction force between metal and metal. If the static friction force after the fifth test was greater than 500 g, it was evaluated as "Good." If the static friction force was 400 g or more but less than 500 g, it was evaluated as "Average." If the static friction force was less than 400 g, it was evaluated as "Poor." If it was "Average" or higher, it was evaluated as having a high static friction force. The evaluation results are shown in Table 1.

[0052] Upper test piece: S45C metal ball (diameter 10 mm) Lower test piece: S45C metal plate Load capacity: 3.5 kg Amount of sample oil applied: 0.15g Speed: 0.5mm / sec Temperature: normal temperature Stroke: 10mm

[0053] <Overall rating> If both the evaluation of abrasion resistance and the evaluation of static friction force were "good", the evaluation was "Excellent", if one of the evaluation of abrasion resistance and the evaluation of static friction force was "good" and the other was "fair", the evaluation was "good", if both the evaluation of abrasion resistance and the evaluation of static friction force were "fair", the evaluation was "fair", and if either the evaluation of abrasion resistance or the evaluation of static friction force was "poor", the evaluation was "poor".

[0054] Example 2 A lubricating grease composition was prepared in the same manner as in Example 1, except that the amount of calcium carbonate A was changed to 10 parts by mass and 10 parts by mass of melamine cyanurate A (average particle size: 2.0 μm, product name "MC-6000", manufactured by Nissan Chemical Industries, Ltd.) was further added as a thickener. The evaluation results are shown in Table 1.

[0055] Example 3 A lubricating grease composition was prepared in the same manner as in Example 1, except that the blending amount of calcium carbonate A was changed to 5 parts by mass and 15 parts by mass of melamine cyanurate A was further added as a thickener. The evaluation results are shown in Table 1.

[0056] Example 4 A lubricating grease composition was prepared in the same manner as in Example 1, except that the blending amount of calcium carbonate A was changed to 2 parts by mass and 18 parts by mass of melamine cyanurate A was further added as a thickener. The evaluation results are shown in Table 1.

[0057] Example 5 A lubricating grease composition was prepared in the same manner as in Example 2, except that calcium carbonate B (primary particle diameter: 0.08 μm, product name "Hakuenka PZ", manufactured by Shiraishi Calcium Co., Ltd.) was used instead of calcium carbonate A. The evaluation results are shown in Table 1.

[0058] Example 6 A lubricating grease composition was prepared in the same manner as in Example 2, except that calcium carbonate C (average particle size: 20 μm, product name "Escalon Grade 1", manufactured by Sankyo Flour Milling Co., Ltd.) was used instead of calcium carbonate A. The evaluation results are shown in Table 1.

[0059] Example 7 A lubricating grease composition was prepared in the same manner as in Example 2, except that melamine cyanurate B (average particle size: less than 14 μm, product name "MC-4000", manufactured by Nissan Chemical Industries, Ltd.) was used instead of melamine cyanurate A. The evaluation results are shown in Table 1.

[0060] Example 8 A lubricating grease composition was prepared in the same manner as in Example 5, except that calcium carbonate D (average particle size: 30 μm, product name SFT-2000, manufactured by Sankyo Flour Milling Co., Ltd.) was used instead of calcium carbonate B. The evaluation results are shown in Table 1.

[0061] Example 9 A lubricating grease composition was prepared in the same manner as in Example 1, except that the amount of calcium carbonate A was changed to 18 parts by mass and 2 parts by mass of polytetrafluoroethylene (average particle size: 4.0 μm, product name "Dyneon (registered trademark) TF9207Z", manufactured by 3M Japan Ltd.) was further added as a thickener. The evaluation results are shown in Table 1.

[0062] (Comparative Example 1) A lubricating grease composition was prepared in the same manner as in Example 1, except that the blending amounts of perfluoropolyether A and perfluoropolyether B were changed to 42 parts by mass and 43 parts by mass, respectively, and 15 parts by mass of melamine cyanurate A was added instead of calcium carbonate A as a thickener. The evaluation results are shown in Table 2.

[0063] (Comparative Example 2) A lubricating grease composition was prepared in the same manner as in Example 1, except that the amount of calcium carbonate A was changed to 15 parts by mass and 5 parts by mass of polytetrafluoroethylene was further added as a thickener. The evaluation results are shown in Table 2.

[0064] (Comparative Example 3) A lubricating grease composition was prepared in the same manner as in Example 2, except that polytetrafluoroethylene was used instead of melamine cyanurate A. The evaluation results are shown in Table 2. Note that the wear resistance was not measured or evaluated because the static friction force evaluation was judged to be "×".

[0065] Comparative Example 4 A lubricating grease composition was prepared in the same manner as in Example 3, except that polytetrafluoroethylene was used instead of melamine cyanurate A. The evaluation results are shown in Table 2. Note that the static friction force was not measured or evaluated because the wear resistance evaluation was judged to be "×".

[0066] (Comparative Example 5) A lubricating grease composition was prepared in the same manner as in Example 1, except that the blending amounts of perfluoropolyether A and perfluoropolyether B were changed to 39.5 parts by mass and 41 parts by mass, respectively, and 19.5 parts by mass of polytetrafluoroethylene was added instead of calcium carbonate A as the thickener. The evaluation results are shown in Table 2.

[0067] (Comparative Example 6) A lubricating grease composition was prepared in the same manner as in Example 1, except that 10 parts by mass of melamine cyanurate A and 10 parts by mass of polytetrafluoroethylene were added as thickeners instead of calcium carbonate A. The evaluation results are shown in Table 2.

[0068] (Comparative Example 7) Polyα-olefin (40℃ kinematic viscosity: 30mm 2A base oil containing 58 parts by weight of DURASYN® 166 (manufactured by Ineos Oligomers Japan) and sebacic acid and carboxylic acid monostearylamide were blended in a mixing and stirring vessel so that the barium complex soap thickener was blended in the amounts shown in Table 2. The mixture was then heated and stirred at 80 to 130°C, after which barium hydroxide was added to cause a saponification reaction, forming the barium complex soap. After the saponification reaction, the mixture was cooled to form a gel-like substance, to which 20 parts by weight of calcium carbonate A was added as a further thickener. The mixture was then stirred and processed in a three-roll mill to produce a lubricating grease composition. The evaluation results are shown in Table 2. Regarding wear resistance, the static friction force evaluation was rated "X," so it was not measured or evaluated.

[0069] [Table 1]

[0070] [Table 2]

[0071] The components shown in Tables 1 and 2 are as follows: The values ​​for each component in Tables 1 and 2 are expressed in parts by mass.

[0072] <Base oil> Perfluoropolyether A: Product name "FOMBLIM (registered trademark) M03" (manufactured by Solvay Specialty Polymers Japan, kinematic viscosity at 40°C: 17 mm 2 / s) Perfluoropolyether B: Product name "FOMBLIM (registered trademark) M15" (manufactured by Solvay Specialty Polymers Japan, kinematic viscosity at 40°C: 85 mm 2 / s) Polyα-olefin: Product name "DURASYN (registered trademark) 166" (manufactured by Ineos Oligomers Japan, kinematic viscosity at 40°C: 30 mm 2 / s) <Thickener> Calcium carbonate A: Product name "Escalon #3500" (manufactured by Sankyo Flour Milling Co., Ltd., average particle size: 1.0 μm) Calcium carbonate B: Product name: "Hakuenka PZ" (Shiraishi Calcium Co., Ltd., primary particle size: 0.08 μm) Calcium carbonate C: Product name: "Escalon Grade 1" (manufactured by Sankyo Flour Milling Co., Ltd., average particle size: 20 μm) Calcium carbonate D: Product name "SFT-2000" (manufactured by Sankyo Flour Milling Co., Ltd., average particle size: 30 μm) Melamine cyanurate A: Product name "MC-6000" (Nissan Chemical Industries, Ltd., average particle size: 2.0 μm) Melamine cyanurate B: Product name "MC-4000" (Nissan Chemical Industries, Ltd., average particle size: less than 14 μm) Polytetrafluoroethylene: Product name "Dyneon (registered trademark) TF9207Z" (manufactured by 3M Japan, average particle size: 4.0 μm) Barium complex soap

[0073] As shown in Table 1, in Examples 1 to 9, the lubricating grease compositions contained a base oil containing perfluoropolyether, calcium carbonate alone or in addition to calcium carbonate, a predetermined amount of melamine cyanurate, and a thickener that may further contain a predetermined amount of polytetrafluoroethylene. Therefore, the resulting lubricating grease compositions exhibited high static friction and excellent wear resistance when metal members slid against each other. In particular, Examples 1 to 3 and 5 to 9, which contained more than 10% by mass but not more than 100% by mass of calcium carbonate relative to the total mass of the thickener, were given an overall rating of "Good," demonstrating superior lubricating performance. Furthermore, Example 1, which used calcium carbonate with an average particle size of 10 μm or less and the calcium carbonate content was 100% by mass relative to the total mass of the thickener, and Examples 2, 3, and 5, which similarly used calcium carbonate with an average particle size of 10 μm or less and the melamine cyanurate content was more than 0% by mass but not more than 90% by mass relative to the total mass of the thickener, were given an overall rating of "Excellent," demonstrating even higher lubricating performance.

[0074] On the other hand, in Comparative Example 1, which did not use calcium carbonate as a thickener but used melamine cyanurate instead, the wear depth was high and the wear resistance was poor. Also, in Comparative Examples 2 and 3, which used calcium carbonate and polytetrafluoroethylene as thickeners but in which the polytetrafluoroethylene content exceeded 20 mass% relative to the total mass of the thickener, high static friction force was not obtained, and in Comparative Example 4, in which the polytetrafluoroethylene content was 75 mass% relative to the total mass of the thickener, the wear depth was unmeasurable and the wear resistance was poor.

[0075] In Comparative Example 5, in which calcium carbonate was not used as a thickener but polytetrafluoroethylene was used instead, the wear depth was high and the wear resistance was poor. In Comparative Example 6, in which calcium carbonate was not used as a thickener but melamine cyanurate and polytetrafluoroethylene were used instead, the wear depth was unmeasurable and the wear resistance was poor.

[0076] In Comparative Example 7, which did not use perfluoropolyether as the base oil but instead used synthetic hydrocarbon oil, and which also used barium complex soap in addition to calcium carbonate as a thickener, high static friction force was not obtained. [Industrial Applicability]

[0077] The lubricating grease composition of the present invention has high static friction force when metal members slide against each other and has excellent wear resistance, and is therefore effective for application to parts where contact occurs between metal parts, such as power transmission devices such as gears, belts, and chains, rolling bearings, and sliding bearings.

Claims

1. A lubricating grease composition comprising a base oil and a thickener, the base oil comprises at least one perfluoropolyether; the thickener contains, relative to the total mass of the thickener, 25% by mass or more and 100% by mass or less of calcium carbonate and 0% by mass or more and 75% by mass or less of melamine cyanurate; The content of polytetrafluoroethylene relative to the total mass of the thickener is 0% by mass, The lubricating grease composition, wherein the content of the calcium carbonate relative to the total mass of the lubricating grease composition is 2 mass % or more and 20 mass % or less.

2. 2. The lubricating grease composition according to claim 1, wherein the calcium carbonate has an average particle size of 30 μm or less.

3. The average particle size of calcium carbonate is 10 μm or less, and 3. The lubricating grease composition according to claim 1, wherein the content of calcium carbonate is 100% by mass, or the content of melamine cyanurate having an average particle size of 10 μm or less is more than 0% by mass and not more than 75% by mass, relative to the total mass of the thickener.

4. The lubricating grease composition according to any one of claims 1 to 3, which is used in sliding parts between metal members.

Images