Grease composition

Abstract

To provide a grease composition which has excellent compatibility with nonpolar polymer materials and which exhibits superior heat resistance.SOLUTION: A grease composition contains a base oil and a thickener, wherein the base oil contains a polyalkylene glycol-based compound represented by formula (1), R1O-(EO)m-(PO)n-R2 (1) (wherein, in formula (1), R1 represents an alkyl group having 1 to 3 carbon atoms, R2 represents a methyl group or hydrogen, EO represents an oxyethylene group, PO represents an oxypropylene group, EO and PO are randomly added, m represents an average added mole number of EO and is a number of 1 to 8, n represents an average added mole number of PO and is a number of 5 to 30, a mass ratio EO:PO of EO to PO is 10:90 to 20:80, and in the compound represented by formula (1), a mass ratio of a compound Me in which R2 is a methyl group to a compound H in which R2 is hydrogen, compound Me:compound H, is 50:50 to 100:0), the base oil may further contain another base oil, a content of the other base oil is 70 mass% or less based on a total mass of the base oil, and the thickener is a diurea compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a grease composition that has excellent compatibility with non-polar polymeric materials and excellent heat resistance. [Background technology]

[0002] Grease is used in various mechanical parts, such as gears, in automotive parts, home appliances, electronic information devices, and office automation equipment. To prevent grease leakage to other parts or the intrusion of water and other foreign matter from the outside, sealants are often installed in lubricated areas. Nitrile rubber (NBR) is commonly used as a sealant due to its oil resistance, processability, and low cost. However, NBR is prone to degradation in high and low temperature environments, which can lead to the ingress of water and other foreign matter, resulting in poor lubrication and rust, shortening the lifespan of mechanical parts. Therefore, ethylene propylene diene rubber (EPDM), which has excellent cold resistance, ozone resistance, heat resistance, and water resistance, is widely used, although it is slightly less oil-resistant than NBR. Styrene butadiene rubber (SBR) is also widely used as a sealant. While many resins are used in automotive parts, polypropylene (PP), which emits less CO2 during manufacturing than other resins, has attracted attention in recent years due to its low CO2 emissions and is expected to see expanded application. On the other hand, hydrocarbon oils such as mineral oil and poly-alphaolefins, which are often used as base oils for greases, tend to corrode non-polar polymer materials such as EPDM, SBR, and PP, so polyalkylene glycol compounds are widely used instead. Electrohydraulic brakes, a type of automotive component, often use EPDM in their peripheral components. The ball screws of these peripheral components are commonly made with lithium soap greases, which use polyoxyalkylene or its ether derivatives (polyalkylene glycol compounds) as the base oil, since these greases do not corrode EPDM. However, as operating temperatures have become more severe in recent years, lithium soap greases may not be able to adequately withstand the high temperatures experienced during brake operation due to their insufficient heat resistance. Therefore, there is a need to select thickeners with good heat resistance, such as urea compounds, for greases that are compatible with non-polar polymeric materials such as EPDM, SBR, and PP. Patent Document 1 reports a brake grease composition that uses polyoxypropylene glycol monoether as a base oil and contains a urea-based thickener. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 61-058519 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors of the present invention investigated the grease composition disclosed in Patent Document 1 and found that although it is compatible with non-polar polymeric materials, because the base oil has a hydroxyl group at the end of its structure, when an amine and an isocyanate are reacted in the base oil, the isocyanate group reacts with the hydroxyl group of the base oil to generate impurities, reducing the yield of the thickener and preventing the desired consistency from being achieved. Furthermore, they found that a larger amount of thickener is required to achieve the desired consistency, and that the generated impurities (solids) reduce the fluidity of the grease. An object of the present invention is to provide a grease composition that is highly compatible with non-polar polymeric materials and has excellent heat resistance. [Means for solving the problem]

[0005] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by using, as a base oil, a polyalkylene glycol-based compound having oxyethylene groups and oxypropylene groups in a specific ratio and arrangement and with an adjusted ratio of terminal methyl groups. That is, the present invention has the following configuration. [1] Contains a base oil and a thickener, The base oil contains a polyalkylene glycol compound represented by formula (1), R 1 O-(EO) m -(PO) n -R 2 (1) (In formula (1), R 1 represents an alkyl group having 1 to 3 carbon atoms, and R 2 represents a methyl group or hydrogen, EO represents an oxyethylene group, PO represents an oxypropylene group, EO and PO are added randomly, m represents the average number of moles of EO added and is a number from 1 to 8, n represents the average number of moles of PO added and is a number from 5 to 30, the mass ratio of EO to PO, EO:PO, is 10:90 to 20:80, and in the compound represented by formula (1), R 2 The compounds Me and R are methyl groups. 2 The mass ratio of compound Me to compound H, in which M is hydrogen, is compound Me:compound H, which is 50:50 to 100:0. The base oil may further comprise other base oils, The content of the other base oil is 70 mass% or less based on the total mass of the base oil, A grease composition, wherein the thickener is a diurea compound represented by formula (2). R 3 -NHCONH-R 4 -NHCONH-R 5 (2) (In formula (2), R 3 and R 5 may be the same or different and represent a linear alkyl group having 8 to 20 carbon atoms, an aryl group having 6 to 7 carbon atoms, or a cyclohexyl group; R 4represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms. [2] In the compound represented by formula (1), R 2 The compounds Me and R are methyl groups. 2 The grease composition according to [1], wherein the mass ratio of compound Me to compound H, in which Me is hydrogen, is 75:25 to 100:0. [3] The grease composition according to [1] or [2], wherein the base oil contains an ester oil as another base oil. [4] A grease composition according to any one of [1] to [3], which is for a machine part having a member made of at least one non-polar polymer material selected from the group consisting of ethylene propylene diene rubber (EPDM), styrene butadiene rubber (SBR), and polypropylene resin (PP). [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a urea grease composition that has excellent compatibility with non-polar polymeric materials and excellent heat resistance. [Brief explanation of the drawings]

[0007] [Figure 1] These are images of the thickener fiber structure observed with a transmission electron microscope. Figure 1(a) is an example in which the thickener fiber of a diurea compound is clearly observed and no impurities have been generated. Figure 1(b) is an example in which, in addition to the thickener fiber, non-fibrous, amorphous impurities have been generated. DETAILED DESCRIPTION OF THE INVENTION

[0008] The grease composition of the present invention contains a polyalkylene glycol compound represented by formula (1) as a base oil. R 1 O-(EO) m -(PO) n -R 2 (1) In formula (1), R 1represents an alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an i-propyl group, and these may be used alone or in combination of two or more. R 1 By making R an alkyl group having 1 to 3 carbon atoms, it is possible to improve heat resistance and compatibility with non-polar polymeric materials. 1 is preferably a methyl group or an ethyl group, more preferably a methyl group. R 2 represents a methyl group or hydrogen. 2 is preferably a methyl group. EO represents an oxyethylene group, and PO represents an oxypropylene group, and the oxyethylene groups (EO) and oxypropylene groups (PO) are added randomly. The random addition of EO and PO results in excellent low-temperature fluidity (the grease composition retains fluidity even at low temperatures).

[0009] m represents the average number of moles of oxyethylene groups (EO) added (i.e., the average number of repeating oxyethylene groups) and is a number from 1 to 8. m is preferably from 2 to 7, and more preferably from 3 to 5. When m is within this range, heat resistance and low-temperature fluidity are improved. n represents the average number of moles of oxypropylene groups (PO) added (i.e., the average number of repeating oxypropylene groups), and is a number from 5 to 30. n is preferably from 5 to 25, and more preferably from 10 to 20. When n is within this range, heat resistance and low-temperature fluidity are improved. The mass ratio of EO to PO, EO:PO, is 10:90 to 20:80. That is, based on the total mass of the oxyethylene groups (EO) and the oxypropylene groups (PO) contained in formula (1), the mass of EO is 10 to 20% and the mass of PO is 80 to 90%. By having an EO ratio of 10 to 20%, excellent compatibility with non-polar polymeric materials and excellent water resistance can be obtained. In the compound represented by formula (1), R 2 The compound where R is a methyl group is called compound Me.2 When a compound in which R is hydrogen is defined as compound H, the mass ratio of compound Me to compound H, compound Me:compound H, is 50:50 to 100:0. Compound Me:compound H is preferably 60:40 to 100:0, more preferably 75:25 to 100:0, and even more preferably 80:20 to 100:0. 2 Compounds where R is a methyl group 2 By using as the base oil a polyalkylene glycol compound in which the mass ratio of the compound in which is hydrogen falls within this range, when the thickener urea compound is reacted in the base oil to produce the grease, impurities are less likely to be generated due to the reaction between the isocyanate groups and the hydroxyl groups of the base oil, and a decrease in the fluidity (decrease in lubricity) of the grease can be prevented.

[0010] The mass average molecular weight of the polyalkylene glycol compound represented by formula (1) is preferably 500 to 2000, more preferably 700 to 1800, and even more preferably 900 to 1600. When the mass average molecular weight of the polyalkylene glycol compound represented by formula (1) is within this range, the heat resistance and low-temperature fluidity are improved. In this specification, the mass average molecular weight is a value measured by gel permeation chromatography (GPC). That is, in this specification, the mass average molecular weight can be determined by GPC using a SHODEX (registered trademark) GPC101 dedicated GPC system as the system, a SHODEX RI-71s differential refractometer, a SHODEX KF-G guard column, and three SHODEX KF804L columns attached in series, a column temperature of 40°C, tetrahydrofuran as a developing solvent at a flow rate of 1 ml / min, injecting 0.1 ml of a 0.1 mass% tetrahydrofuran solution of the resulting reaction product, and using a BORWIN GPC calculation program to obtain a chromatogram represented by refractive index intensity and elution time.

[0011] The polyalkylene glycol compound of formula (1) can be produced by the following method. Specifically, an alcohol initiator and potassium hydroxide as a catalyst are charged into an autoclave. The air in the autoclave is replaced with dry nitrogen, and the catalyst is completely dissolved at 140°C while stirring. Next, a mixture of ethylene oxide and propylene oxide is added dropwise using a dropping device, and the reaction is carried out for 2 hours at 140°C after the completion of the dropwise addition. Next, potassium hydroxide is charged, and the autoclave is replaced with dry nitrogen. Methyl chloride is then added under pressure at a temperature of 80 to 130°C, and the reaction is carried out for 5 hours. The reaction composition (containing the compound of formula (1) produced) is then removed from the autoclave, neutralized with hydrochloric acid to a pH of 6 to 7, and dehydrated at 100°C under a reduced pressure of -0.095 MPa (50 mmHg) for 1 hour to remove the contained water. The resulting mixture is then filtered to remove the salt produced by the dehydration.

[0012] The grease composition of the present invention may contain only the polyalkylene glycol compound of formula (1) as the base oil, or may contain a mixture of the polyalkylene glycol compound of formula (1) with other grease base oils. The grease composition of the present invention preferably uses an ester oil as another base oil. Examples of ester oils include diesters and polyol esters, with polyol esters being preferred, and esters of neopentyl polyols such as neopentyl glycol, trimethylolpropane, pentaerythritol, and dipentaerythritol with monovalent fatty acids being more preferred. The acid component constituting the ester is not particularly limited, but examples include monovalent fatty acids having 2 to 24 carbon atoms, with monovalent fatty acids having 4 to 18 carbon atoms being preferred. By using the polyalkylene glycol compound of formula (1) and an ester oil together as the base oil, a grease composition can be obtained that is excellent in compatibility with non-polar polymeric materials and has excellent heat resistance. In the grease composition of the present invention, the content of the other base oil is 70% by mass or less, preferably 65% ​​by mass or less, and more preferably 60% by mass or less, based on the total mass of the base oil. The lower limit is not particularly limited, but is preferably 10% by mass or more, and more preferably 20% by mass or more. Furthermore, when an ester oil is used as the other base oil, the content of the ester oil is 70% by mass or less, preferably 65% ​​by mass or less, and more preferably 60% by mass or less, based on the total mass of the base oil. The lower limit is not particularly limited, but is preferably 10% by mass or more, and more preferably 20% by mass or more. By including the other base oil in such a range together with the polyalkylene glycol compound of formula (1) in the base oil, a grease composition can be obtained that has excellent compatibility with non-polar polymeric materials and excellent heat resistance. In the grease composition of the present invention, the content of the polyalkylene glycol compound of formula (1) is preferably 20 to 90 mass%, more preferably 25 to 90 mass%, and even more preferably 30 to 90 mass%, based on the total mass of the composition. By including the polyalkylene glycol compound of formula (1) in such a range, it is possible to obtain a grease composition in which a urea compound having excellent compatibility with non-polar polymeric materials and low impurity content is synthesized. Furthermore, in the grease composition of the present invention, the content of the base oil is preferably 50 to 95 mass%, more preferably 60 to 95 mass%, and even more preferably 65 to 95 mass%, based on the total mass of the composition.

[0013] The kinematic viscosity of the polyalkylene glycol compound represented by formula (1) at 100°C is 4 to 20 mm 2 / s is preferable, and 4 to 15 m 2 The kinematic viscosity of the entire base oil of the present invention at 100°C is more preferably 4 to 20 mm / s. 2 / s is preferable, and 4 to 15 m 2 / s. When the kinematic viscosity at 100°C of the polyalkylene glycol compound or base oil of formula (1) is in this range, the fluidity of the grease at low temperatures can be improved, evaporation at high temperatures can be prevented, and stable lubrication can be ensured. In this specification, the kinematic viscosity is a value measured in accordance with JIS K2283:2000.

[0014] The grease composition of the present invention contains a diurea compound represented by formula (2) as a thickener. R 3 -NHCONH-R 4 -NHCONH-R 5 (2) In formula (2), R 3 and R 5 may be the same or different and represent a linear alkyl group having 8 to 20 carbon atoms, an aryl group having 6 to 7 carbon atoms, or a cyclohexyl group, preferably a linear alkyl group having 8 to 20 carbon atoms or a cyclohexyl group, more preferably a linear alkyl group having 8 to 18 carbon atoms. 3 and R 5 When one of them is a linear alkyl group having 8 to 20 carbon atoms and the other is a cyclohexyl group, the molar ratio of the linear alkyl group having 8 to 20 carbon atoms to the cyclohexyl group is preferably 1:9 to 8:2, and more preferably 1:9 to 7:3. R 4 represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, and is preferably a group derived from tolylene diisocyanate or diphenylmethane-4,4'-diisocyanate, more preferably a group derived from diphenylmethane-4,4'-diisocyanate. The content of the thickener in the grease composition of the present invention is, for example, preferably 4 to 25 mass %, and more preferably 5 to 20 mass %, based on the total mass of the composition. A thickener content within this range is preferable because it gives the grease an appropriate hardness and prevents leakage from lubricated parts.

[0015] The grease composition of the present invention can contain any additives commonly used in grease compositions, as needed. Examples include antioxidants, rust inhibitors, corrosion inhibitors, oiliness agents, viscosity index improvers, extreme pressure agents, and friction modifiers. Examples of antioxidants include amine-based, phenol-based, quinoline-based, and sulfur-based antioxidants, with amine-based or quinoline-based antioxidants being preferred. Examples of rust inhibitors include zinc-based, carboxylic acid-based, carboxylate-based, succinic acid-based, amine-based, sulfonate-based, and naphthenic acid-based antioxidants, with amine-based or naphthenic acid-based antioxidants being preferred, and mixtures thereof being even more preferred. Examples of corrosion inhibitors include thiadiazole-based, benzimidazole-based, and benzotriazole-based inhibitors. Examples of oiliness agents include fatty acids, fatty acid esters, and phosphate esters. The content of the additives is preferably 0.1 to 25 mass %, more preferably 0.3 to 20 mass %, and even more preferably 0.5 to 20 mass %, based on the total mass of the grease composition. By including the additives in such a content, good lubricity and heat resistance are achieved.

[0016] Of the grease compositions of the present invention, those having the following features are particularly preferred. Contains a base oil and a thickener, The base oil contains a polyalkylene glycol compound represented by formula (1), R 1 O-(EO) m -(PO) n -R 2 (1) (In formula (1), R 1 represents a methyl group, and R 2 represents a methyl group or hydrogen, EO represents an oxyethylene group, PO represents an oxypropylene group, EO and PO are added randomly, m represents the average number of moles of EO added and is a number from 1 to 8, n represents the average number of moles of PO added and is a number from 5 to 30, the mass ratio of EO to PO, EO:PO, is 10:90 to 20:80, and in the compound represented by formula (1), R 2 The compounds Me and R are methyl groups. 2The mass ratio of compound Me to compound H, in which M is hydrogen, is compound Me:compound H, which is 80:20 to 100:0. the base oil further comprises an ester oil; The content of the ester oil is 70 mass% or less based on the total mass of the base oil, A grease composition, wherein the thickener is a diurea compound represented by formula (2). R 3 -NHCONH-R 4 -NHCONH-R 5 (2) (In formula (2), R 3 and R 5 may be the same or different and represent a linear alkyl group having 8 to 20 carbon atoms, an aryl group having 6 to 7 carbon atoms, or a cyclohexyl group; R 4 represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms. In this embodiment, a grease composition in which the content of the ester oil is 50% by mass or more and 70% by mass or less based on the total mass of the base oil is also preferred. In this embodiment, a grease composition having a dropping point measured in accordance with JIS K 2220 8. of 240°C or higher is also preferred. In this embodiment, a grease composition for use in a machine part having a member made of at least one non-polar polymer material selected from the group consisting of ethylene propylene diene rubber (EPDM), styrene butadiene rubber (SBR), and polypropylene resin (PP) is also preferred.

[0017] The grease composition of the present invention has excellent heat resistance even when applied to high-temperature environments. The dropping point of the grease composition of the present invention, measured in accordance with JIS K 2220 8, is preferably 200°C or higher, more preferably 220°C or higher, and even more preferably 240°C or higher. Furthermore, the grease composition of the present invention can be used around nonpolar polymeric materials such as ethylene propylene diene rubber (EPDM), styrene butadiene rubber (SBR), and polypropylene resin (PP). In other words, the grease composition of the present invention can be used for machine parts equipped with components made of nonpolar polymeric materials (e.g., sealing materials made of at least one nonpolar polymeric material selected from the group consisting of EPDM and SBR, and components made of PP), and can be used in direct contact with the nonpolar polymeric materials. Even when used in such a state, the grease composition of the present invention can maintain the functionality of components made of these materials without corroding the nonpolar polymeric materials. [Example]

[0018] <Preparation of Test Grease Compositions> In the base oil shown in the table below, 1 mole of 4,4'-diphenylmethane diisocyanate was reacted with 2 moles of a predetermined amine, and the mixture was heated and cooled to obtain a base grease. Additional base oil was added to the above base grease, and the mixture was dispersed using a three-roll mill, and adjusted so that the worked penetration after 60 strokes measured according to JIS K2220 7. (2013) was 280, to obtain a test grease composition. In Comparative Example 4, a grease composition was obtained by blending lithium soap into the base oil. The base oils and thickeners in the table are as follows: Unless otherwise specified, the numbers for the components in the table represent mass % based on the total mass of the composition. (base oil) Polyalkylene glycol compounds (compounds of formula (1) having the structure shown in the table below) Ester oil (product name: Rikemal R-886N, manufactured by Riken Vitamin Co., Ltd., kinematic viscosity at 100°C: 10.5 mm 2 / s) (thickener) Aliphatic diurea A: reaction product of 4,4'-diphenylmethane diisocyanate and octylamine Aliphatic diurea B: Reaction product of 4,4'-diphenylmethane diisocyanate with octylamine and stearylamine (molar ratio of octylamine to stearylamine is 5:5) Alicyclic aliphatic diurea A: Reaction product of 4,4'-diphenylmethane diisocyanate with cyclohexylamine and stearylamine (molar ratio of cyclohexylamine to stearylamine is 7:1) Alicyclic aliphatic diurea B: Reaction product of 4,4'-diphenylmethane diisocyanate with cyclohexylamine and stearylamine (molar ratio of cyclohexylamine to stearylamine is 3:7) Aromatic diurea: reaction product of 4,4'-diphenylmethane diisocyanate with p-toluidine

[0019] The obtained grease compositions of the Examples and Comparative Examples were evaluated by the following test methods and test conditions. The results are shown in Tables 1 and 2. In the following evaluation criteria, ◯ was judged as passing and × was judged as failing. <Urea synthesis> A base grease was prepared by reacting 1 mole of 4.4'-diphenylmethane diisocyanate with 2 moles of a specified amine in a base oil, heating it, and then cooling it. The base oil was then replaced with a solvent, and the thickener fibers were observed using a transmission electron microscope to examine the condition of the thickener. Figure 1 shows an example of the thickener fiber structure observed using a transmission electron microscope. Figure 1(a) shows an example in which diurea compound thickener fibers are clearly observed and no impurities are formed. On the other hand, Figure 1(b) shows an example in which, in addition to the thickener fibers, non-fibrous, amorphous impurities are formed. In the following evaluation criteria, a grease composition observed as in Figure 1(a) is a good example without impurities. [Evaluation criteria] No impurities other than thickener fibers: There are impurities other than thickener fibers: × <Heat resistance> The dropping point was determined according to JIS K 2220 8. (2013) and used as the heat resistance temperature. <Rubber compatibility> The compatibility was evaluated in accordance with JIS K 6258:2016. No. 8 dumbbell EPDM rubber test pieces were used, and after immersing the test pieces in the grease composition at 100°C for 72 hours, their mass and volume were measured. The volume of the test pieces was measured using the water displacement method. The rate of change in the mass and volume of the test pieces before and after immersion was determined, and the compatibility was evaluated using the following criteria. [Evaluation criteria] Mass change rate The mass change rate of the test piece is less than 5%: ○ The mass change rate of the test piece is 5% or more: × Volume change rate The volume change rate of the test piece is less than 5%: ○ The volume change rate of the test piece is 5% or more: ×

[0020] [Table 1]

[0021] [Table 2]

[0022] The grease compositions of Examples 1 to 11 were well formed into greases, exhibited excellent heat resistance of 260° C. or higher, and were also highly compatible with non-polar polymeric materials. On the other hand, in the grease compositions of Comparative Example 1, in which the mass ratio of compound Me to compound H in the compound of formula (1) was 0:100, and Comparative Example 2, in which the mass ratio was 25:75, impurities were generated during urea synthesis, and in order to achieve a consistency of 280, a larger amount of thickener was required than in Examples 1, 3, and 7, in which the same aliphatic diurea A was used. The grease composition of Comparative Example 3, in which the content of the other base oil was 80 mass % based on the total mass of the base oil, did not satisfy compatibility with non-polar polymeric materials. R in the compound of formula (1) 1The grease composition of Comparative Example 4, in which was a butyl group, EO:PO (mass ratio) was 0:100, compound Me:compound H (mass ratio) was 0:100, and lithium soap was used as a thickener, had a low heat resistance of 190°C.

Claims

1. Contains a base oil and a thickener, The base oil contains a polyalkylene glycol compound represented by formula (1), 2 1 9-(59) m -(0) n -2 2 (1) (In formula (1), R 1 represents an alkyl group having 1 to 3 carbon atoms, and R 2 represents a methyl group or hydrogen, EO represents an oxyethylene group, PO represents an oxypropylene group, EO and PO are added randomly, m represents the average number of moles of EO added and is a number from 1 to 8, n represents the average number of moles of PO added and is a number from 5 to 30, the mass ratio of EO to PO is EO:PO is 10:90 to 20:80, and in the compound represented by formula (1), R 2 is a methyl group, and 2 is hydrogen, the mass ratio of compound Me:compound H is 50:50 to 100:

0. The base oil may further comprise other base oils, The content of the other base oil is 70 mass% or less based on the total mass of the base oil, A grease composition, wherein the thickener is a diurea compound represented by formula (2). R 3 -NHGNH-R 4 -NHGNH-R 5 (2) (In formula (2), R 3 and R 5 may be the same or different and represent a linear alkyl group having 8 to 20 carbon atoms, an aryl group having 6 to 7 carbon atoms, or a cyclohexyl group; R 4 represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms.

2. In the compound represented by formula (1), R 2 is a methyl group, and 2 2. The grease composition according to claim 1, wherein the mass ratio of compound Me to compound H, in which M is hydrogen, is 75:25 to 100:

0.

3. The grease composition according to claim 1, wherein the base oil contains an ester oil as another base oil.

4. The grease composition according to any one of claims 1 to 3, which is for use in a machine part having a member made of at least one non-polar polymer material selected from the group consisting of ethylene propylene diene rubber (EPDM), styrene butadiene rubber (SBR), and polypropylene resin (PP).

Images