Lubricating grease composition

Abstract

To provide a lubricating grease composition that can achieve suppression of oil release while maintaining low torque and good muddy water resistance in a sliding portion between a rubber element and a metallic component.SOLUTION: A lubricating grease composition comprises a base oil, a thickener, and a solid lubricant, wherein the content of the thickener is 2 wt.% or more and 15 wt.% or less relative to the overall weight of the lubricating grease composition, the solid lubricant includes melamine isocyanurate, and the content of the solid lubricant is 10 wt.% or more and 50 wt.% or less relative to the overall weight of the lubricating grease composition.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Conventionally, lubricating grease compositions have been used as lubricants in the sliding parts of gears and sliding members. One such lubricating grease composition has been proposed, containing a base oil, a thickener, and melamine cyanurate (MCA) and polytetrafluoroethylene (PTFE) as solid lubricants (see, for example, Patent Document 1). In the grease composition described in Patent Document 1, the blending amounts of melamine cyanurate and polytetrafluoroethylene are within a predetermined range relative to the total mass of the grease composition, and the blending ratios of melamine cyanurate and polytetrafluoroethylene are also within a predetermined range. This achieves a grease composition that has both lubricating performance by reducing the dynamic friction coefficient and static functionality by increasing the static friction coefficient.

[0003] Furthermore, in automotive parts such as hub seals and differential side seals, grease is used as a lubricant in the sliding parts where rubber members and metal members come into contact. Such sliding parts are prone to high friction, which is known to have a significant impact on the fuel efficiency of automobiles, so low friction is required. In order to improve the low-friction function, lowering the viscosity of the base oil contained in the lubricating grease composition has been studied.

[0004] Furthermore, in recent years, the automotive industry has strongly demanded weight reduction and improved fuel economy. In response to this trend, there is a demand for lower torque in rotating automotive components, such as oil seals, to improve fuel economy. Meanwhile, automotive components used outdoors are used in harsh environments, including, in extreme cases, exposure to muddy water, so their elastic components (oil seals, etc.) are required to be resistant to muddy water. However, because muddy water resistance is inversely related to torque performance, it is extremely difficult to achieve both improved muddy water resistance and low torque.

[0005] The most effective way to reduce torque in sealing grease is to lower the viscosity of the base oil. However, when a low-viscosity base oil is used, unintended oil separation (leaking of the base oil) is likely to occur if the lubricating grease composition is left for a long time or when it is affected by the external environment. If the base oil leaks to the outside, there is a concern that it may contaminate surrounding components or deteriorate the lubricating performance of sliding parts.

[0006] Such oil separation can be suppressed by increasing the content of thickener in the lubricating grease composition, but this also results in increased torque and deterioration of muddy water resistance. Furthermore, increasing the content of thickener makes the grease too hard, making mass production and application using a grease applicator difficult. Therefore, it has been extremely difficult to suppress oil separation while maintaining the inherent torque performance and muddy water resistance of sealing greases used in sliding parts between rubber and metal members. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-13351 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention provides a lubricating grease composition that can suppress oil separation while maintaining low torque and good muddy water resistance in sliding portions between rubber members and metal members. [Means for solving the problem]

[0009] A lubricating grease composition according to an embodiment of the present invention contains a base oil, a thickener, and a solid lubricant, the content of the thickener being 2% by weight or more and 15% by weight or less based on the total weight of the lubricating grease composition, and the solid lubricant containing melamine isocyanurate, and the content of the solid lubricant being 10% by weight or more and 50% by weight or less based on the total weight of the lubricating grease composition.

[0010] In one embodiment of the present invention, the solid lubricant is melamine isocyanurate.

[0011] In one embodiment of the present invention, the thickener contains at least one of a metal soap compound, a complex metal soap compound, and a urea compound.

[0012] In one embodiment of the present invention, the base oil comprises a synthetic hydrocarbon oil.

[0013] In one embodiment of the present invention, a lubricating grease composition prepared using a centrifuge is filled into a container as a sample, and when the sample filling section having a polytetrafluoroethylene membrane filter is subjected to rotation at 1420 rpm at 20 to 25°C for 60 minutes, the amount of oil separated by centrifugation calculated by the following formula is 10% by weight or less. Amount of oil separated by centrifugation (wt%) = (weight of oil separated from sample / weight of filled sample) x 100

[0014] In one embodiment of the present invention, the water resistance time measured by the muddy water resistance test described below under the test conditions described below is 501 hours or more. <Muddy water resistance test> After applying the lubricating grease composition to each seal lip using a seal rotation tester, a test is carried out under the following test conditions to measure the time it takes for muddy water to penetrate into the seal. <Test conditions> Amount applied: 0.40g Interference: MIN Sealing liquid: Muddy water (JIS type 8, Kanto loam powder 10% by weight) Fluid volume: Mud bath at the center of the shaft Operation cycle: 1100 rpm x 20 hours, then stop for 4 hours

[0015] In one embodiment of the present invention, the rotational torque measured by the torque test described below under the test conditions described below is 15 N·cm or less. <Torque test> After applying the lubricating grease composition to each seal lip portion using a seal rotation tester, the rotation torque is measured under the following test conditions. <Test conditions> Amount applied: 0.53g Interference: MID Rotation speed: 1000 rpm Break-in: 1000 rpm x 5 minutes Exam duration: 2 hours

[0016] In one embodiment of the present invention, the unworked penetration measured in accordance with JIS K2220 7:2013 is 170 or more and 265 or less.

[0017] In one embodiment of the present invention, the lubricating grease composition is used in sliding parts between rubber members and metal members. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a lubricating grease composition that can suppress oil separation while maintaining low torque and good resistance to muddy water in sliding portions between rubber members and metal members. DETAILED DESCRIPTION OF THE INVENTION

[0019] 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, 2% by weight to 15% by weight of a thickener, and 10% by weight to 50% by weight of melamine isocyanurate as a solid lubricant. By blending a predetermined amount of thickener and a predetermined amount of melamine isocyanurate as a solid lubricant into the lubricating grease composition, it is possible to suppress unintended oil separation (outflow of base oil) while maintaining low torque and good muddy water resistance at the sliding portions between rubber and metal members. The components contained in the lubricating grease composition according to this embodiment and the resulting properties will be described in detail below.

[0020] <Base oil> In the present embodiment, the base oil is not particularly limited, and examples thereof include synthetic hydrocarbon oils (PAO), mineral oils, ester oils, and glycol oils. Each of the base oils may be used alone, or two or more may be mixed together. Examples of synthetic hydrocarbon oils include polyα-olefins, ethylene-α-olefin copolymers, polybutene, alkylbenzenes, and alkylnaphthalenes, with polyα-olefins being preferred. Examples of mineral oils include paraffinic hydrocarbons, naphthenic hydrocarbons, aromatic hydrocarbons, and olefinic hydrocarbons. Examples of ester oils include diesters, polyol esters, and aromatic esters. Examples of glycol oils include polyalkylene glycols.

[0021] Examples of synthetic hydrocarbon oils include poly-α-olefins, ethylene-α-olefin oligomers, ethylene-α-olefin copolymers, polybutenes, alkylbenzenes, alkylnaphthalenes, etc., with poly-α-olefins being preferred. The synthetic hydrocarbon oils may be used alone or in combination of two or more.

[0022] The kinematic viscosity of the base oil is 60mm at 40°C. 2 / s or less, and 30 mm at 40°C 2 / s or less is more preferable, and 18 mm 2 It is more preferable that the kinematic viscosity of the base oil is 18 mm / s or less at 40°C. When a plurality of base oils are used, the kinematic viscosity of the base oil is expressed as the kinematic viscosity of the entire base oil. Therefore, for example, even if a lubricating grease composition contains a plurality of base oils, the kinematic viscosity of the entire base oil is 18 mm / s or less at 40°C. 2 / s or less, 60 mm at 40°C 2 In particular, the kinematic viscosity of the base oil may be greater than 18 mm / s at 40°C. 2 On the other hand, the lower limit of the kinematic viscosity of the base oil is not particularly limited as long as it can impart low torque characteristics to the lubricating grease composition. 2The kinematic viscosity of the base oil can be measured in accordance with JIS K 2283:2000.

[0023] Commercially available base oils having such a kinematic viscosity include, for example, "DURASYN (registered trademark) 162" (poly-α-olefin, kinematic viscosity at 40°C: 5mm) manufactured by Ineos Oligomers Japan Ltd. 2 / s), INEOS Oligomers Japan's "DURASYN (registered trademark) 164" (poly α-olefin, kinematic viscosity at 40°C: 18 mm 2 / s), INEOS Oligomers Japan's "DURASYN (registered trademark) 166" (poly α-olefin, kinematic viscosity at 40°C: 30 mm 2 / s), and ExxonMobil's "SpectraSyn (registered trademark) 4" (poly α-olefin, kinematic viscosity at 40°C: 18 mm 2 Synthetic hydrocarbon oil such as "DOS" (diester, kinematic viscosity at 40°C: 11 mmHg) manufactured by Daihachi Chemical Industry Co., Ltd. 2 / s), NOF Corporation's "Unistar (registered trademark) H-334R" (polyol ester, 40°C kinematic viscosity: 20 mm 2 Ester oil such as "Newpol 50HB-100" (polyalkylene glycol, kinematic viscosity at 40°C: 19 mmHg) manufactured by Sanyo Chemical Industries, Ltd. 2 Examples of suitable glycol oils include glycol oils such as PEG-14 glycolate and PEG-14 glycolate.

[0024] The total content of the base oil contained in the lubricant composition is preferably 35% by mass or more and 88% by mass or less, more preferably 40% by mass or more and 70% by mass or less, and even more preferably 45% by mass or more and 60% by mass or less, based on the total mass of the lubricant composition.

[0025] <Thickener> In the present embodiment, the thickener is not particularly limited, but preferably contains at least one selected from a metal soap compound, a complex metal soap compound, and a urea compound. One type of thickener may be used alone, or two or more types may be mixed together. From the viewpoint of further reducing oil separation, the thickener preferably contains at least one type of complex metal soap compound and a urea compound, more preferably contains a complex metal soap compound, and even more preferably is a complex metal soap compound.

[0026] Examples of metal soap compounds include lithium soap, calcium soap, and aluminum soap, with lithium soap being preferred. Here, the lithium soap is a soap obtained by saponifying an aliphatic carboxylic acid or ester with lithium hydroxide. Examples of lithium soap include lithium salts of aliphatic monocarboxylic acids having 12 to 24 carbon atoms and lithium salts of aliphatic monocarboxylic acids having 12 to 24 carbon atoms and at least one hydroxy group, with lithium stearate and lithium 12-hydroxystearate being particularly preferred.

[0027] Examples of complex metal soap compounds include lithium complex soaps, calcium complex soaps, and barium complex soaps, with lithium complex soaps and barium complex soaps being preferred, and lithium complex soaps being more preferred. Here, the lithium complex soap is a soap obtained by saponifying multiple aliphatic carboxylic acids or esters with lithium hydroxide, and the barium complex soap is a soap obtained by saponifying multiple aliphatic carboxylic acids or esters with barium hydroxide. Examples of lithium complex soaps include lithium salts of aliphatic monocarboxylic acids and aliphatic dicarboxylic acids, and lithium salts of two or more aliphatic monocarboxylic acids.

[0028] The urea compound is not particularly limited, but examples thereof include diurea compounds, triurea compounds, tetraurea compounds, polyurea compounds, etc., and diurea compounds are preferred. Examples of the diurea compound include diurea compounds represented by the following formula (1):

[0029] R 2 -NHCONH-R 1 -NHCONHR 3 ···(1)

[0030] In the above formula (1), R 1 represents an aromatic hydrocarbon group having 6 to 15 carbon atoms, and R 2 and R 3 are each independently an aromatic hydrocarbon group having 6 to 18 carbon atoms, a cyclohexyl group, an alkylcyclohexyl group having 7 to 12 carbon atoms, an alkyl group having 8 to 22 carbon atoms, or an alkenyl group having 8 to 22 carbon atoms.

[0031] The diurea compound represented by the formula (1) can be obtained by reacting an amine with a diisocyanate compound by a known method. Examples of the amine include aromatic amines having 6 to 18 carbon atoms, cyclohexylamine, alkylcyclohexylamines having 7 to 12 carbon atoms, alkyl or alkylamines having 8 to 22 carbon atoms, and mixtures thereof. Examples of the diisocyanate compound include diphenylmethane-4,4'-diisocyanate, 2,4'-tolylene diisocyanate, and 2,6-tolylene diisocyanate, which are preferred because of their excellent availability, and diphenylmethane-4,4'-diisocyanate is more preferred because of its excellent heat resistance.

[0032] The content of the thickener in the lubricating grease composition is preferably 2 to 15% by weight, and more preferably 5 to 20% by weight, based on the total weight of the lubricating grease composition. A thickener content of 2% by weight or more allows the lubricating grease composition to remain semi-solid and provide low torque characteristics, while a content of 15% by weight or less allows the lubricating grease composition to have good muddy water resistance.

[0033] <Solid lubricant> In this embodiment, the lubricating grease composition contains melamine isocyanurate (MCA) as a solid lubricant, and the solid lubricant is preferably melamine isocyanurate. By using melamine cyanurate as a solid lubricant, the lubricating grease composition can be imparted with low torque characteristics, and also exhibits the effects of imparting good muddy water resistance and suppressing oil separation.

[0034] The content of the solid lubricant contained in the lubricating grease composition is preferably 10% by weight or more and 50% by weight or less, and more preferably 20% by weight or more and 40% by weight or less, based on the total weight of the lubricating grease composition. When the content of the solid lubricant, particularly melamine isocyanurate, is 10% by weight or more, the lubricating grease composition exhibits an oil separation suppression effect. Furthermore, when the content of the solid lubricant, particularly melamine isocyanurate, is 50% by weight or less, the lubricating grease composition can be imparted with good muddy water resistance.

[0035] It is preferable to use melamine cyanurate alone as the solid lubricant, but it may also be used in combination with other solid lubricants such as polytetrafluoroethylene (PTFE), molybdenum disulfide, organic molybdenum, calcium carbonate, boron nitride, and silane nitride.

[0036] <Other additives> 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, oiliness agents, etc. The type and amount of additives used can be determined as desired depending on the purpose.

[0037] Examples of the antioxidant include phenol-based antioxidants such as 2,6-di-tert-butyl-4-methylphenol and 4,4'-methylenebis(2,6-ditert-butylphenol); amine-based antioxidants such as alkyldiphenylamines (alkyl groups having 4 to 20 carbon atoms), triphenylamine, phenyl-α-naphthylamine, phenothiazine, alkylated phenyl-α-naphthylamine, phenithiazine, and alkylated phenothiazine; and further, phosphoric acid-based antioxidants and sulfur-based antioxidants.

[0038] Examples of extreme pressure additives 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 paraffins and chlorinated diphenyls; and metal organic compounds such as zinc dialkyldithiophosphate (ZnDTP) and molybdenum dialkyldithiocarbamate (MoDTP).

[0039] Examples of the rust inhibitor include fatty acids, fatty acid amines, metal sulfonates, alkyl sulfonates, alkyl sulfonic acid amine salts, oxidized paraffin, and polyoxyethylene alkyl ethers.

[0040] Examples of corrosion inhibitors include benzotriazole, benzimidazole, and thiadiazole.

[0041] Examples of viscosity index improvers include polymethacrylate, ethylene-propylene copolymer, polyisobutylene, polyalkylstyrene, and hydrogenated styrene-isoprene copolymer.

[0042] Examples of oily agents include fatty acids, higher alcohols, polyhydric alcohols, polyhydric alcohol esters, aliphatic esters, aliphatic amines, and fatty acid monoglycerides.

[0043] <Oil separation properties> The oil separation property of the lubricating grease composition according to this embodiment is evaluated by measuring the amount of base oil separated by applying centrifugal pressure to a predetermined amount of the lubricating grease composition (amount of centrifugal oil separation). Specifically, a lubricating grease composition prepared using a centrifuge is filled into a container as a sample, and a sample filling section equipped with a polytetrafluoroethylene (PTFE) membrane filter is rotated at 1420 rpm at 20 to 25°C for 60 minutes. The amount of centrifugal oil separation is calculated using the following formula: Amount of oil separated by centrifugation (wt%) = (weight of oil separated from sample / weight of filled sample) x 100

[0044] Such centrifugal oil separation amount is preferably 10% by weight or less, more preferably 7% by weight or less, even more preferably 5% by weight or less, and even more preferably 3% by weight or less.

[0045] <Muddy water resistance> The muddy water resistance of the lubricating grease composition according to this embodiment is evaluated by measuring the water resistance time measured in a muddy water resistance test under predetermined test conditions using a predetermined amount of the lubricating grease composition. Specifically, the lubricating grease composition is applied to each seal lip using a seal rotation tester, and then the test is conducted under the following test conditions to measure the time until muddy water penetrates into the seal. If this water resistance time is 501 hours or longer, it can be evaluated as exhibiting good muddy water resistance. <Test conditions> Amount applied: 0.40g Interference: MIN Sealing liquid: Muddy water (JIS type 8, Kanto loam powder 10% by weight) Fluid volume: Mud bath at the center of the shaft Operation cycle: 1100 rpm x 20 hours, then stop for 4 hours

[0046] <Torque performance> The torque performance of the lubricating grease composition according to this embodiment is evaluated by measuring the rotational torque under specified test conditions using a predetermined amount of the lubricating grease composition. Specifically, the lubricating grease composition is applied to each seal lip using a seal rotation tester, and then the rotational torque is measured under the following test conditions. If the rotational torque is 15 N·cm or less, it can be evaluated that low torque has been achieved. <Test conditions> Amount applied: 0.53g Interference: MID Rotation speed: 1000 rpm Break-in: 1000 rpm x 5 minutes Exam time: 2 hours

[0047] <Unmixed consistency> The lubricating grease composition according to this embodiment preferably has a consistency at a level that allows it to be pumped using a grease pump used during production, machine application, etc. Therefore, the unworked penetration measured in accordance with JIS K2220 7:2013 is preferably 170 or more and 265 or less, more preferably 175 or more and 260 or less, and even more preferably 180 or more and 240 or less. Having an unworked penetration of 170 or more can prevent problems from occurring during pumping using a grease pump.

[0048] <Method for producing lubricating grease composition> The lubricating grease composition according to this embodiment can be produced by mixing the above-mentioned base oil, thickener, solid lubricant, and optionally other additives 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.

[0049] The lubricating grease composition according to the present embodiment is suitable for use in sliding parts between rubber members and metal members, and is effective as a lubricating grease composition for automotive hub bearings used in hub units, as well as industrial bearings and sealing members where low torque is required in sliding parts between rubber members and metal members.

[0050] Examples of rubber for the rubber member include nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), acrylic rubber (ACM), styrene butadiene rubber (SBR), silicone rubber (VMQ), fluororubber (FKM), ethylene propylene rubber (EPDM), chloroprene rubber (CR), urethane rubber (U), butadiene rubber (BR), butyl rubber (IIR), isoprene rubber (IR), etc. Examples of metal for the metal member include various metals such as stainless steel (SUS), iron, steel, and copper.

[0051] 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.

[0052] Based on the above-described embodiments, the present invention relates to the following [1] to [9]. [1] A lubricating grease composition comprising a base oil, a thickener, and a solid lubricant, The content of the thickener is 2% by weight or more and 15% by weight or less based on the total weight of the lubricating grease composition, the solid lubricant comprises melamine isocyanurate, and A lubricating grease composition, characterized in that the content of the solid lubricant is 10% by weight or more and 50% by weight or less, based on the total weight of the lubricating grease composition. [2] The lubricant composition according to [1] above, wherein the solid lubricant is melamine isocyanurate. [3] The lubricating grease composition according to [1] or [2] above, wherein the thickener comprises at least one of a metal soap compound, a complex metal soap compound, and a urea compound. [4] The lubricating grease composition according to any one of [1] to [3] above, wherein the base oil comprises a synthetic hydrocarbon oil. [5] The lubricating grease composition according to any one of the above [1] to [4], wherein when the lubricating grease composition prepared in a container using a centrifuge is filled as a sample, and a sample filling section having a polytetrafluoroethylene membrane filter is subjected to rotation at 1420 rpm at 20 to 25°C for 60 minutes, the amount of oil separated by centrifugation calculated by the following formula is 10% by weight or less. Amount of oil separated by centrifugation (wt%) = (weight of oil separated from sample / weight of filled sample) x 100 [6] The lubricating grease composition according to any one of [1] to [5] above, having a water resistance time of 501 hours or more as measured by the muddy water resistance test described below under the test conditions described below. <Muddy water resistance test> After applying the lubricating grease composition to each seal lip using a seal rotation tester, a test is carried out under the following test conditions to measure the time it takes for muddy water to penetrate into the seal. <Test conditions> Amount applied: 0.40g Interference: MIN Sealing liquid: Muddy water (JIS type 8, Kanto loam powder 10% by weight) Fluid volume: Mud bath at the center of the shaft Operation cycle: 1100 rpm x 20 hours, then stop for 4 hours [7] The lubricating grease composition according to any one of [1] to [6] above, having a rotational torque of 15 N·cm or less as measured by the torque test described below under the test conditions described below. <Torque test> After applying the lubricating grease composition to each seal lip portion using a seal rotation tester, the rotation torque is measured under the following test conditions. <Test conditions> Amount applied: 0.53g Interference: MID Rotation speed: 1000 rpm Break-in: 1000 rpm x 5 minutes Exam time: 2 hours [8] The lubricating grease composition according to any one of [1] to [7] above, having an unworked penetration of 170 or more and 265 or less, measured in accordance with JIS K2220 7:2013. [9] The lubricating grease composition according to any one of [1] to [8] above, which is used in sliding parts between rubber members and metal members. [Example]

[0053] 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 depart from the spirit of the invention.

[0054] Example 1 Poly α-olefin A (40°C kinematic viscosity: 18 mm 2 / s, product name "DURASYN (registered trademark) 164" manufactured by Iones Oligomers Japan Co., Ltd.) 37 parts by weight and poly α-olefin B (kinematic viscosity at 40°C: 5 mm 2 A base oil containing 17 parts by weight of thickener B (lithium complex soap) was blended with 10 parts by weight of thickener B (lithium complex soap) and reacted, heated, and then cooled. 36 parts by weight of solid lubricant A (melamine isocyanurate, product name "MC-6000", manufactured by Nissan Chemical Industries, Ltd.) was added to the resulting gel-like substance, stirred, and then kneaded using a roll mill or high-pressure homogenizer to prepare a lubricating grease composition.

[0055] <Oil separation properties> Using a centrifuge (product name "H-36α", manufactured by Kokusan Co., Ltd.), the obtained lubricating grease composition was filled into a container as a sample, and the sample filling section, which had a polytetrafluoroethylene membrane filter, was rotated at 1420 rpm at 20 to 25°C for 60 minutes, and the amount of centrifugal oil separation calculated using the following formula was evaluated. If the amount of centrifugal oil separation was 10% by weight or less, it was determined that oil separation was suppressed. The results are shown in Table 1. Amount of oil separated by centrifugation (wt%) = (weight of oil separated from sample / weight of filled sample) x 100

[0056] <Muddy water resistance> After applying the lubricating grease composition to each seal lip using a seal rotation tester, a test was conducted under the following test conditions to measure the time until muddy water penetrated into the seal. If the water resistance time was 501 hours or more, it was evaluated as "Good" indicating good muddy water resistance, and if the water resistance time was less than 501 hours, it was evaluated as "Poor" indicating insufficient muddy water resistance. The results are shown in Table 1. <Test conditions> Amount applied: 0.40g Interference: MIN Sealing liquid: Muddy water (JIS type 8, Kanto loam powder 10% by weight) Fluid volume: Mud bath at the center of the shaft Operation cycle: 1100 rpm x 20 hours, 4 hours off

[0057] <Torque performance> After applying the lubricating grease composition to each seal lip using a seal rotation tester, the rotational torque was measured under the following test conditions. If the rotational torque was 15 N·cm or less, low torque was achieved and the result was evaluated as "Good." If the rotational torque was greater than 15 N·cm, the torque was not reduced and the result was evaluated as "Poor." The results are shown in Table 1. <Test conditions> Amount applied: 0.53g Interference: MID Rotation speed: 1000 rpm Break-in: 1000 rpm x 5 minutes Exam duration: 2 hours

[0058] <Unmixed consistency> The unworked penetration of the obtained lubricating grease composition was measured in accordance with JIS K2220 7:2013, and the results are shown in Table 1.

[0059] Example 2 A lubricating grease composition was prepared in the same manner as in Example 1, except that the blending amounts of poly-α-olefin A were changed to 34 parts by weight, poly-α-olefin B to 14 parts by weight, thickener B to 2 parts by weight, and solid lubricant A to 50 parts by weight. The evaluation results of each property are shown in Table 1.

[0060] Example 3 A lubricating grease composition was prepared in the same manner as in Example 2, except that 48 parts by weight of poly-α-olefin B was blended as the base oil instead of the mixture of poly-α-olefin A and poly-α-olefin B. The evaluation results of each property are shown in Table 1.

[0061] Example 4 A lubricating grease composition was prepared in the same manner as in Example 1, except that the blending amounts of poly-α-olefin A were changed to 53 parts by weight, poly-α-olefin B to 22 parts by weight, thickener B to 15 parts by weight, and solid lubricant A to 10 parts by weight. The evaluation results of each property are shown in Table 1.

[0062] Example 5 A lubricating grease composition was prepared in the same manner as in Example 1, except that 5 parts by weight of thickener A (lithium soap) was used instead of thickener B, and the amounts of poly-α-olefin A and poly-α-olefin B were changed to 41 parts by weight and 18 parts by weight, respectively. The evaluation results of each property are shown in Table 1.

[0063] Example 6 A lubricating grease composition was prepared in the same manner as in Example 1, except that 7 parts by weight of thickener C (aliphatic diurea) was used instead of thickener B, and the amount of poly-α-olefin A was changed to 40 parts by weight. The evaluation results of each property are shown in Table 1.

[0064] Example 7 Instead of poly α-olefin B, poly α-olefin C (40°C kinematic viscosity: 30 mm 2A lubricating grease composition was prepared in the same manner as in Example 1, except that 41 parts by weight of DURASYN® 166 (manufactured by Iones Oligomers Japan) was blended, and the amount of thickener B was changed to 12 parts by weight, and the amount of solid lubricant A was changed to 30 parts by weight. The evaluation results of each property are shown in Table 1.

[0065] (Comparative Example 1) A lubricating grease composition was prepared in the same manner as in Example 1, except that 85 parts by weight of poly-α-olefin A was used as the base oil instead of the mixture of poly-α-olefin A and poly-α-olefin B, the amount of thickener B was changed to 15 parts by weight, and no solid lubricant was added. The evaluation results of each property are shown in Table 2.

[0066] (Comparative Example 2) A lubricating grease composition was prepared in the same manner as in Comparative Example 1, except that the blending amount of poly-α-olefin A was changed to 75 parts by weight and the blending amount of thickener B was changed to 25 parts by weight. The evaluation results of the friction coefficient in each speed range are shown in Table 2.

[0067] (Comparative Example 3) A lubricating grease composition was prepared in the same manner as in Example 4, except that the amount of thickener B was changed to 25 parts by weight and no solid lubricant was added. The evaluation results of each property are shown in Table 2.

[0068] Comparative Example 4 A lubricating grease composition was prepared in the same manner as in Comparative Example 3, except that the blending amounts of poly-α-olefin A, poly-α-olefin B, and thickener B were changed to 49 parts by weight, 21 parts by weight, and 30 parts by weight, respectively. The evaluation results of each property are shown in Table 2.

[0069] (Comparative Example 5) A lubricating grease composition was prepared in the same manner as in Example 2, except that the blending amounts of poly-α-olefin A and poly-α-olefin B were changed to 35 parts by weight and 15 parts by weight, respectively, and no thickener was added. The evaluation results of each property are shown in Table 2.

[0070] (Comparative Example 6) A lubricating grease composition was prepared in the same manner as in Example 2, except that the blending amount of poly-α-olefin B was changed to 15 parts by weight and the blending amount of thickener B was changed to 1 part by weight. The evaluation results of each property are shown in Table 2.

[0071] (Comparative Example 7) A lubricating grease composition was prepared in the same manner as in Example 1, except that the blending amounts of poly-α-olefin A were changed to 54 parts by weight, poly-α-olefin B to 23 parts by weight, thickener B to 15 parts by weight, and solid lubricant A to 8 parts by weight. The evaluation results of each property are shown in Table 2.

[0072] (Comparative Example 8) A lubricating grease composition was prepared in the same manner as in Example 2, except that the blending amount of poly-α-olefin A was changed to 34 parts by weight and the blending amount of solid lubricant A was changed to 51 parts by weight. The evaluation results of each property are shown in Table 2.

[0073] (Comparative Example 9) A lubricating grease composition was prepared in the same manner as in Example 1, except that the same amount of solid lubricant B (polytetrafluoroethylene, product name "Dyneon (registered trademark) TF9205", manufactured by 3M Japan Ltd.) was blended in place of solid lubricant A. The evaluation results of each property are shown in Table 2.

[0074] (Comparative Example 10) A lubricating grease composition was prepared in the same manner as in Example 1, except that 50 parts by weight of solid lubricant C (calcium carbonate, product name "Calfin 600", manufactured by Adachi Lime Industry Co., Ltd.) was used instead of solid lubricant A, and the amounts of poly-α-olefin A and poly-α-olefin B were changed to 28 parts by weight and 12 parts by weight, respectively. The evaluation results of each property are shown in Table 2.

[0075] (Comparative Example 11) A lubricating grease composition was prepared in the same manner as in Example 1, except that 86 parts by weight of poly-α-olefin C was used as the base oil instead of the mixture of poly-α-olefin A and poly-α-olefin B, the amount of thickener B was changed to 14 parts by weight, and no solid lubricant was added. The evaluation results of each property are shown in Table 2.

[0076] [Table 1]

[0077] [Table 2]

[0078] The components shown in Tables 1 and 2 are as follows: The values ​​for each component in Tables 1 and 2 are in parts by weight.

[0079] <Base oil> Polyα-olefin A: Product name "DURASYN (registered trademark) 164" (manufactured by Iones Oligomers Japan, kinematic viscosity at 40°C: 18 mm 2 / s) Polyα-olefin B: Product name "DURASYN (registered trademark) 162" (manufactured by Iones Oligomers Japan, kinematic viscosity at 40°C: 5 mm 2 / s) Polyα-olefin C: Product name "DURASYN (registered trademark) 166" (manufactured by Iones Oligomers Japan, kinematic viscosity at 40°C: 30 mm 2 / s) <Thickener> Thickener A: Lithium soap (lithium salt of 12-hydroxystearic acid) Thickener B: Lithium complex soap (lithium salt of 12-hydroxystearic acid and azelaic acid) Thickener C: Aliphatic diurea (diurea compound of diphenylmethane diisocyanate and octylamine) <Solid lubricant> Solid lubricant A: Melamine isocyanurate (product name "MC6000", manufactured by Nissan Chemical Industries, Ltd.) Solid lubricant B: Polytetrafluoroethylene (product name: Dyneon (registered trademark) TF9205, manufactured by 3M Japan) Solid lubricant C: calcium carbonate (product name "Calfin 600", manufactured by Adachi Lime Industry Co., Ltd.)

[0080] As can be seen from Table 1, in Examples 1 to 7, in which the lubricating grease compositions contained a base oil, 2 to 15% by weight of a thickener, and 10 to 50% by weight of melamine isocyanurate as a solid lubricant, the centrifugal oil separation amount in terms of oil separation characteristics was 10% by weight or less, and the muddy water resistance and torque performance were both evaluated as "Good." Therefore, a lubricating grease composition was realized that was able to suppress unintended oil separation while maintaining low torque and good muddy water resistance in sliding portions between rubber and metal members.

[0081] On the other hand, in Comparative Example 1, which did not contain a solid lubricant, the centrifugal oil separation rate in the oil separation characteristics was 21% by weight, and unintended oil separation could not be suppressed. Furthermore, in Comparative Examples 2, 3, and 4, which contained more than 15% by weight of thickener, the mud water resistance was evaluated as "X," and did not exhibit good mud water resistance. Furthermore, in Comparative Examples 2 and 3, the centrifugal oil separation rate in the oil separation characteristics was 15%, and unintended oil separation could not be suppressed.

[0082] In Comparative Example 5, which did not contain a thickener, the torque performance was evaluated as "×" and it was not possible to reduce the torque. In addition, in Comparative Example 6, in which the thickener content was less than 2 wt%, the torque performance was also evaluated as "×" and it was not possible to reduce the torque.

[0083] In Comparative Example 7, in which the content of melamine isocyanurate as a solid lubricant was less than 10% by weight, the centrifugal oil separation amount in the oil separation characteristics was 15%, and unintended oil separation could not be suppressed.Furthermore, in Comparative Example 8, in which the content of melamine isocyanurate as a solid lubricant was more than 50% by weight, the evaluation of muddy water resistance was "×", and it did not show good muddy water resistance.

[0084] In Comparative Examples 9 and 10, which did not contain melamine isocyanurate as a solid lubricant, the evaluation of torque performance was "×" in both cases, and it was not possible to achieve low torque. Furthermore, in Comparative Example 10, the evaluation of muddy water resistance was also "×", and it did not exhibit good muddy water resistance.

[0085] In addition, in Comparative Example 11, which contained a different base oil from Comparative Example 1 but did not contain any solid lubricant like Comparative Example 1, the centrifugal oil separation amount in the oil separation characteristics was 12 wt %, and unintended oil separation could not be suppressed. [Industrial Applicability]

[0086] The lubricating grease composition of the present invention is suitable for use in sliding portions between rubber members and metal members, and is therefore effective for application to automobile parts such as hub seals and differential side seals.

Claims

1. A lubricating grease composition comprising a base oil, a thickener, and a solid lubricant, The content of the thickener is 2% by weight or more and 15% by weight or less based on the total weight of the lubricating grease composition, the solid lubricant comprises melamine isocyanurate, and A lubricating grease composition, characterized in that the content of the solid lubricant is 10% by weight or more and 50% by weight or less, based on the total weight of the lubricating grease composition.

2. 10. The lubricant composition of claim 1, wherein the solid lubricant is melamine isocyanurate.

3. 3. The lubricating grease composition according to claim 1, wherein the thickener comprises at least one of a metal soap compound, a complex metal soap compound, and a urea compound.

4. 3. The lubricating grease composition of claim 1, wherein the base oil comprises a synthetic hydrocarbon oil.

5. 3. The lubricating grease composition according to claim 1, wherein when the lubricating grease composition prepared using a centrifuge is filled into a container as a sample, and a sample filling section having a polytetrafluoroethylene membrane filter is subjected to rotation at 1,420 rpm at 20 to 25°C for 60 minutes, the amount of oil separated by centrifugation calculated by the following formula is 10% by weight or less: Amount of oil separated by centrifugation (wt%) = (weight of oil separated from sample / weight of filled sample) x 100

6. 3. The lubricating grease composition according to claim 1, wherein the water resistance time measured by the muddy water resistance test described below under the test conditions described below is 501 hours or more. <Mud water resistance test> After applying the lubricating grease composition to each seal lip using a seal rotation tester, a test is carried out under the following test conditions to measure the time it takes for muddy water to penetrate into the seal. <Test conditions> Amount applied: 0.40 g Interference: MIN Sealing liquid: Muddy water (JIS type 8 Kanto loam powder 10% by weight) Fluid volume: Mud bath at the center of the shaft Operation cycle: 1100 rpm x 20 hours, then stopped for 4 hours

7. 3. The lubricating grease composition according to claim 1, wherein the rotational torque measured by the torque test described below under the test conditions described below is 15 N·cm or less. <Torque test> After applying the lubricating grease composition to each seal lip portion using a seal rotation tester, the rotation torque is measured under the following test conditions. <Test conditions> Amount applied: 0.53g Interference: MID Rotation speed: 1000 rpm Break-in: 1000 rpm x 5 minutes Exam duration: 2 hours

8. 3. The lubricating grease composition according to claim 1, wherein the unworked penetration measured in accordance with JIS K2220 7:2013 is 170 or more and 265 or less.

9. 3. The lubricating grease composition according to claim 1, which is used in sliding parts between rubber members and metal members.

Images