Grease composition

Abstract

According to the present invention, provided is a grease composition containing (a) a compound having a phosphate ester moiety, (b) a base oil, and (c) a thickener, the grease composition having a maximum non-seizure load of 980 N or more as measured in accordance with ASTM D-2596.

Description

Technical Field

[0001] The present invention relates to a grease composition useful for applications requiring extreme pressure (EP) properties. Background Art

[0002] Generally, the following operation is performed: a load-resistant additive is added to the grease used under severe lubrication conditions. As such load-resistant additives, known are oiliness agents such as long-chain fatty acids, wear-resistant agents such as phosphoric acid esters having sulfur, phosphorus, chlorine, etc. in the molecule, metal dithiophosphates, organic ionic compounds, and organic halogen compounds, and EP agents, solid additives such as molybdenum disulfide, graphite, boron nitride, and polytetrafluoroethylene (Non-Patent Document 1). As a representative phosphate ester EP agent, tricresyl phosphate is known.

[0003] On the other hand, typical uses of compounds having a phosphate ester moiety other than EP agents are surfactants (eg, Patent Document 1).

[0004] Patent Document 1 describes that surfactants such as polyoxyethylene alkyl ether phosphate, polyoxyalkylene alkyl ether phosphate or salts thereof can be used as oiliness agents, but does not describe or suggest that they can be used as anti-wear agents or EP agents.

[0005] Patent Document 2 describes that a titanate-based or aluminum-based coupling agent can be used to prevent low-temperature chattering of grease for electrical contacts, but does not describe or suggest that the coupling agent can be used as an EP agent.

[0006] Patent Document 3 achieves wear resistance by combining (A) a base oil, (B) an acidic phosphate ester or the like, and (c) an isothiazolin-based compound.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2013-116991

[0010] Patent Document 2: Japanese Patent No. 4002637

[0011] Patent Document 3: Japanese Patent Application Publication No. 2021-138814

[0012] Non-patent literature

[0013] Non-patent document 1: Lubrication Economics, Temporary Supplement, 2010, No. 543, Lubrication Communications Co., Ltd. Summary of the invention

[0014] Problems to be solved by the invention

[0015] An object of the present invention is to provide a grease composition having excellent EP properties.

[0016] Means for solving problems

[0017] The present inventors have found that this problem can be solved by including a compound having a phosphate ester portion in a molecular structure, which has not been used as an EP agent in a grease composition. That is, according to the present invention, the following inventions are provided.

[0018] 1. A grease composition comprising (a) a compound having a phosphate ester moiety, (b) a base oil and (c) a thickener, wherein the maximum no-seizure load measured according to ASTM D-2596 is 980 N or more.

[0019] 2. The grease composition according to item 1 above, comprising 0.1 to 20% by mass of the component (a) based on the total mass of the composition.

[0020] 3. The grease composition according to 1 or 2 above, wherein the component (a) is (a1) a compound represented by the following chemical formula (1).

[0021] [Chemistry 1]

[0022]

[0023] In the formula, R 1 is an alkyl group having 1 to 24 carbon atoms or an aryl group which may have a substituent, A 1 O is an alkyleneoxy group having 2 to 4 carbon atoms, n is an integer of 0 to 30, m is an integer of 1 to 3, and M is a hydrogen atom, an alkali metal, a Group II metal, an ammonium group, or an organic ammonium group.

[0024] 4. The grease composition according to item 1 or 2 above, wherein component (a) is at least one coupling agent (a2) having a phosphate ester moiety in the molecule selected from the group consisting of (a2-1) silane coupling agents, (a2-2) titanium coupling agents, (a2-3) aluminum coupling agents and (a2-4) zirconium oxide coupling agents.

[0025] 5. The grease composition according to 1 or 2 above, wherein the seizure load (melting load) measured in accordance with ASTM D-2596 is 1960 N or more.

[0026] 6. Use of the grease composition described in 1 or 2 above as an extreme pressure wear-resistant grease for bearings, gears, automobile parts, industrial machinery parts, etc.

[0027] Effects of the Invention

[0028] According to the present invention, it is possible to provide a grease composition having excellent wear resistance, particularly EP properties evaluated according to ASTM D-2596. DETAILED DESCRIPTION

[0029] (a) Compounds having a phosphate moiety

[0030] The component (a) of the present invention is a compound having a phosphate moiety in the molecule. The component (a) is a compound that can make the maximum no-seizure load measured in accordance with ASTM D-2596 be 980 N or more by being included in the base grease.

[0031] Examples of the component (a) include (a1) a compound represented by the following chemical formula (1) and (a2) a coupling agent containing a phosphoric acid ester in the molecule.

[0032] (a1) The compound represented by the following chemical formula (1) is a compound currently used as an anionic surfactant in a wide range of technical fields.

[0033] [Chemistry 2]

[0034]

[0035] In the formula, R 1 It is a straight-chain or branched alkyl group having 1 to 24 carbon atoms (preferably a straight-chain or branched alkyl group having 3 to 18 carbon atoms) or an aryl group which may have a substituent (preferably an aryl group having a substituent such as phenol, dodecylphenol, dinonylphenol, styrenated phenol, phenol derivatives, alkylbenzenes, etc.).

[0036] A 1 O is an alkyleneoxy group having 2 to 4 carbon atoms, preferably an ethyleneoxy group or a 1,2-propyleneoxy group, and more preferably an ethyleneoxy group.

[0037] n represents the number of moles of the alkyleneoxy group added, and is an integer of 0 to 30. Preferably, it is 0 to 12. When n is 2 or more, n AOs may be the same or different. 1 The addition mode of O)n- may be any of random addition, block addition or alternating addition.

[0038] m is an integer of 1 to 3, and preferably 1 or 2.

[0039] M is a hydrogen atom, an alkali metal, a Group II metal, an ammonium group or an organic ammonium group, preferably Na, Ca, an ammonium group or an organic ammonium group.

[0040] The compound of formula (1) is preferably a monoester or a diester.

[0041] More preferably, it is the following monoester or diester: In formula (1), R 1A is a linear or branched alkyl group having 3 to 18 carbon atoms, a linear or branched alkenyl group having 3 to 18 carbon atoms, or an aromatic group having a substituent such as phenol, dodecylphenol, dinonylphenol, styrenated phenol, a phenol derivative, or an alkylbenzene, 1 O is ethyleneoxy or 1,2-propyleneoxy, n is 0 to 12, m is 1 or 2, and M is Na, Ca, ammonium or organic ammonium.

[0042] Examples of anionic surfactants containing a phosphate moiety that can be used in the present invention other than the compound represented by formula (1) include glycerol fatty acid esters, polyoxyalkylene alkyl ether phosphoric acids, or salts thereof. Specifically, examples include trioxyethylene alkyl (12-15) ether phosphoric acid, nonaoxyethylene alkyl (12-15) ether phosphoric acid, trioxyethylene stearyl ether phosphoric acid, tetraoxyethylene lauryl ether phosphoric acid, isopropyl ether phosphoric acid, butyl ether phosphoric acid, isohexyl ether phosphoric acid, alkyl (C6-C10) ether phosphoric acid, dodecyl ether phosphoric acid, lauryl ether phosphoric acid, isotridecyl ether phosphoric acid, alkyl (12-15) ether phosphoric acid, monooxyethylene isohexyl ether phosphoric acid, tetraoxyethylene alkyl (C6-C10) ether phosphoric acid, dioxyethylene dodecyl ether phosphoric acid, trioxyethylene isotridecyl ether phosphoric acid, hexaoxyethylene isotridecyl ether phosphoric acid, decaoxyethylene isotridecyl ether phosphoric acid, and the like. Ether phosphoric acid, dioxyethylene stearyl ether phosphoric acid, hexaoxyethylene phenyl ether phosphoric acid, dioxyethylene dodecyl phenyl ether phosphoric acid, octaoxyethylene dinonylphenol ether phosphoric acid, dodecyloxyethylene dinonylphenol ether phosphoric acid, undecyloxyethylene styrenated phenol ether phosphoric acid, undecyloxyethylene phenol derivative ether phosphoric acid, sodium butyl ether phosphate, sodium tetraoxyethylene dodecyl ether phosphate, calcium hexaoxyethylene isotridecyl ether phosphate, hexaoxyethylene phenol ether phosphoric acid, trioxyethylene isotridecyl ether phosphoric acid (the above are manufactured by Toho Chemical Industry Co., Ltd., Phosphanol series), polyoxypropylene alkyl ether phosphoric acid, polyoxybutylene alkyl ether phosphoric acid or salts thereof. Specific examples of commercially available products include DISPARLON DA-325, DISPARLON DA-375, HIPLAAD ED152, HIPLAAD ED152 manufactured by Kusumoto Chemicals, and Hypermer KD23, Hypermer KD24, Crodafos 03A, and Crodafos 010A manufactured by Croda.

[0043] As (a1), polyoxyalkylene alkyl ether phosphoric acid or its salt is preferred, polyoxyethylene alkyl ether phosphoric acid or its salt is more preferred, and trioxyethylene alkyl (12-15) ether phosphoric acid, nonaoxyethylene alkyl (12-15) ether phosphoric acid, trioxyethylene stearyl ether phosphoric acid, and tetraoxyethylene lauryl ether phosphoric acid are further preferred.

[0044] (a2) Coupling agent having a phosphate moiety in the molecule

[0045] The component (a2) is preferably at least one selected from the group consisting of (a2-1) a silane coupling agent, (a2-2) a titanium coupling agent, (a2-3) an aluminum coupling agent, and (a2-4) a zirconium oxide coupling agent.

[0046] Specific examples include bis[2-diphenolphosphinoethylmethylsilylethyltriethoxysilane (SIB1091.0 manufactured by AZmax Co., Ltd.), 2-(diphenylphosphino)ethyldimethylethoxysilane (SID4557.5 manufactured by AZmax Co., Ltd.), diphenylphosphinoethyltriethoxysilane (SID4558.0 manufactured by AZmax Co., Ltd.), diethylphosphinoethyltriethoxysilane (SID3412.0 manufactured by AZmax Co., Ltd.), 3-trihydroxysilylpropylmethylphosphonic acid sodium salt (SIT8378.5.0 manufactured by AZmax Co., Ltd.), tetraisopropylbis(dioctylphosphite)titanate (Plenact 41B manufactured by Ajinomoto Co., Ltd.), isopropyltri(dioctylpyrophosphate)titanate, diisopropylbis(dioctylpyrophosphate)titanate (Plenact 41B manufactured by Ajinomoto Co., Ltd.), 338X), tetrakis(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphite titanate (Plenact KR55 manufactured by Ajinomoto), tetraoctylbis(ditridecylphosphite) titanate (Plenact KR46B manufactured by Ajinomoto), bis(dioctyl pyrophosphate)ethylene titanate (Plenact KR238S manufactured by Ajinomoto), etc.

[0047] As the compound having a phosphate moiety used in the present invention, it is preferred that at least one compound be selected from the group consisting of trioxyethylene alkyl (12-15) ether phosphate, nonaoxyethylene alkyl (12-15) ether phosphate, trioxyethylene stearyl ether phosphate, tetraoxyethylene lauryl ether phosphate, isopropyl tri(dioctyl pyrophosphate) titanate and diisopropyl bis(dioctyl pyrophosphate) titanate.

[0048] The content of component (a) is preferably 0.1 to 20% by mass, more preferably 0.1 to 15% by mass, and even more preferably 0.5 to 5% by mass based on the total mass of the composition. By containing 0.1 to 20% by mass of component (a), a grease composition having excellent load bearing capacity can be obtained.

[0049] (b) Base oil

[0050] The base oil that can be used in the present invention may be a mineral oil or a synthetic oil, and is not particularly limited. As specific examples, mineral oil (e.g., paraffin-based or cycloparaffin-based mineral oil), synthetic hydrocarbon oil (e.g., polyalphaolefin (an oil obtained by polymerizing a linear alpha-olefin having 6 to 18 carbon atoms such as 1-decene and then hydrogenating it), polybutene, alkylnaphthalene, alkylbenzene, ethylene-alpha-olefin copolymer), ester oil (e.g., diester, polyol ester), ether oil (e.g., polyalkylene glycol, polyphenylene ether), fluorine oil, silicone oil, ionic liquid, etc. It should be noted that the synthetic oil may be a so-called biomass oil made from biological resources produced by animals and plants as raw materials. For example, biomass ester oil synthesized from various fatty acids and alcohols using vegetable oils as raw materials, and biomass hydrocarbon oil using vegetable oils such as palm oil, corn oil, and soybean oil may also be used. The base oil may be used alone or as a mixture of two or more. These base oils may be used alone or as various mixed oils.

[0051] The base oil is preferably a mineral oil, a synthetic hydrocarbon oil (particularly a poly-α-olefin), or a mixed oil thereof, more preferably a mineral oil or a poly-α-olefin, and most preferably a mineral oil (particularly a paraffin-based mineral oil).

[0052] The kinematic viscosity of the base oil at 40°C is, for example, 30 to 500 mm 2 / s, preferably 50 to 300 mm 2 / s, more preferably 70 to 200 mm 2 / s (for example, 90~150mm 2 / s). It should be noted that the kinematic viscosity is measured by a method in accordance with JIS K2283.

[0053] The content of the base oil is, for example, 60 to 97 mass %, or preferably 70 to 95 mass %, based on the total mass of the grease composition.

[0054] (c) Thickener

[0055] The thickener used in the present invention can be used without particular limitation as long as it is a thickener commonly used in grease compositions. Specifically, metal soaps, complex metal soaps, urea thickeners, urethane thickeners, carbon black, bentonite, silica compounds, polytetrafluoroethylene (PTFE), etc. are mentioned. Preferred are thickeners selected from the group consisting of metal soaps, complex metal soaps, urea thickeners, and silica, and more preferred are metal soaps and urea compounds.

[0056] Specific examples of metal soaps include aluminum soaps, calcium soaps, lithium soaps, sodium soaps, barium soaps, etc. Lithium soaps are preferred. Lithium stearate soaps and 12-hydroxystearate lithium soaps are more preferred. 12-hydroxystearate lithium soaps are particularly preferred.

[0057] Specific examples of complex metal soaps include lithium complex soaps, calcium complex soaps (for example, calcium sulfonate complexes can use thickeners formed by combining calcium salts of higher or lower fatty acids and calcium salts of inorganic acids in calcium sulfonate and calcium carbonate. Lithium complex soaps are specifically complex soaps composed of lithium salts of 12-hydroxystearic acid and lithium salts of azelaic acid), aluminum complex soaps, and the like.

[0058] Examples of urea thickeners include diurea thickeners obtained by reacting aromatic amines, aliphatic amines, cyclohexylamines, or a mixture of two or more thereof with aromatic diisocyanates. Such diurea thickeners can be represented by the following formula (2).

[0059] R 10 -NHCONH-R 20 -NHCONH-R 30 (2)

[0060] In the formula, R 10 and R 30 may be the same or different, and are an aromatic hydrocarbon group having 6 to 15 carbon atoms, a linear or branched alkyl group having 5 to 20 carbon atoms, or a cyclohexyl group, R 20 It is a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms.

[0061] Specific examples of aromatic diisocyanates include toluene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, etc. Specific examples of aromatic amines include p-toluidine, aniline, naphthylamine, etc. Specific examples of aliphatic amines include octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, nonadecylamine, eicosylamine, etc.

[0062] As the diurea thickener, preferably R 10 and R 30 is a straight-chain alkyl group having 8 carbon atoms, R 20 It is a thickener with a group derived from diphenylmethane diisocyanate. The diurea thickener is the reaction product of octylamine and diphenylmethane diisocyanate.

[0063] As the diurea thickener, it is also preferred to include R 10 is a straight-chain alkyl group having 18 carbon atoms, R 30 For cyclohexyl, R 20 A compound having a group derived from diphenylmethane diisocyanate, R 10 and R 30 is a straight-chain alkyl group having 18 carbon atoms, R 20 A compound having a group derived from diphenylmethane diisocyanate and R 10 and R30 For cyclohexyl, R 20 A diurea thickener is a compound derived from a group of diphenylmethane diisocyanate. The diurea thickener is a reaction product of octylamine and cyclohexylamine with diphenylmethane diisocyanate.

[0064] As the diurea thickener, the most preferred is R 10 and R 30 is a straight-chain alkyl group having 8 carbon atoms, R 20 It is a diurea thickener derived from the radical of diphenylmethane diisocyanate.

[0065] As for silicon dioxide (silica), the average particle diameter of primary particles is preferably 0.1 μm or less, and more preferably 0.05 μm or less.

[0066] The viscosity of the grease composition of the present invention is preferably 100 to 440. The content of the thickener in the composition of the present invention is an amount required to obtain the above viscosity. Specifically, it is preferably 3 to 30% by mass, more preferably 5 to 25% by mass, relative to the entire grease composition. The viscosity is more preferably 150 to 360. It should be noted that the term "consistency" in this specification refers to the 60-times work cone penetration measured in accordance with JIS K 2220 7.

[0067] The maximum no-seizure load (LNSL) specified by ASTM D-2596 of the grease composition of the present invention is 980N or more. If converted into surface pressure, it is a high load of 7GPa, which is a harsh condition comparable to the rolling contact or rolling 4-ball test conditions of metal and ceramic hybrid bearings. The larger the value of the maximum no-seizure load, the better the EP property. In this test, from the perspective of EP performance, the maximum no-seizure load (LNSL) is preferably 1236N or more, and more preferably 1569N or more. It should be noted that LNSL represents the limit load until the film breaks due to the load and seizure occurs due to direct contact between the steel balls.

[0068] The grease composition of the present invention preferably has a sintering load (WP) of 1960N or more as specified by ASTM D-2596. This is a standard required by robots and gear devices. Regarding the sintering load (WP), the larger the value of the sintering load, the better the EP property. In JIS K2220, as a load-resistant grease, the sintering load (WP) in this test is specified to be 2450N or more. From the viewpoint of EP property, it is preferably 2450N or more, and more preferably 3089N or more. It should be noted that WP represents the load when the friction heat generated by the sliding of the steel balls causes the steel balls to be melted and integrated.

[0069] The OK value of the grease composition of the present invention is preferably 900N or more. If converted into surface pressure, it is a high load of 4.5GPa, which exceeds the maximum surface pressure of CVJ 3.5GPa, and is a rolling sliding test condition and a rolling condition of a crank pin for a motorcycle. Regarding the OK value, the larger the value, the better the EP property. From the viewpoint of EP property, it is preferably 1000N or more, and more preferably 1100N or more. It should be noted that the OK value represents the tight front load of the bite in the SRV step rise. The SRV test is described later.

[0070] In this specification, the EP property at high speed is evaluated by the high-speed four-ball load bearing capacity test (Shell four-ball test), and the EP property at low speed is evaluated by the SRV test. The wear caused by rotational motion, point contact, and sliding friction is mainly evaluated by the LNSL and WP measured by the Shell four-ball test, and the wear EP property caused by reciprocating motion, surface contact, and sliding friction is mainly evaluated by the OK value measured by the SRV test. The excellent results for various motion modes, PV conditions, and parameters mean that the EP property can be exerted at various levels.

[0071] [Other additives]

[0072] The grease composition of the present invention may further contain other additives as needed. Specific examples of other additives include antioxidants (e.g., phenolic and amine-based), extreme pressure agents (e.g., zinc dithiocarbamate, zinc dithiophosphate, and organic molybdenum), rust inhibitors (e.g., carboxylic acid-based such as zinc naphthenate; sulfonic acid-based such as Zn sulfonic acid and Ca sulfonic acid), viscosity index improvers, dispersants, and combinations thereof. However, it is preferred that isothiazolin-based compounds such as 2-methyl-4-isothiazoline-3-one, 2-methyl-4,5-trimethylene-4-isothiazoline-3-one, 5-chloro-2-methyl-4-isothiazoline-3-one, 2-n-octylisothiazoline-3-one, 4,5-dichloro-2-n-octylisothiazoline-3-one, 1,2-benzisothiazolin-3-one, N-n-butyl-1,2-benzisothiazolin-3-one, or combinations thereof are not contained.

[0073] When other additives are added to the grease composition, the content thereof varies depending on the type, but is, for example, 0.1 to 10% by mass, preferably 0.5 to 5% by mass, relative to the total mass of the grease composition.

[0074] The grease composition of the present invention is particularly useful as an extreme-pressure anti-wear grease for bearings, gears, automobile parts, industrial machinery parts, and the like used under severe lubrication conditions.

[0075] Example

[0076] 1. Preparation of grease composition

[0077] (1) Preparation of base grease with aliphatic diurea as thickener

[0078] In base oil (kinematic viscosity at 40°C is 100 mm 2 / s mineral oil), 1 mol of 4',4-diphenylmethane diisocyanate and 2 mol of octadecylamine were reacted, heated, cooled, and then kneaded with a three-roll mill to obtain a base grease. The ratio of the thickener in the base grease was 7% by mass.

[0079] (2) Preparation of base grease with 12-hydroxy lithium stearate as thickener

[0080] Base oil (kinematic viscosity at 40°C is 100 mm 2 12-Hydroxystearic acid was added to a 100% / s mineral oil, heated, and then a lithium hydroxide aqueous solution was added to cause a saponification reaction. After the reaction was completed, the mixture was heated to a specified temperature, cooled, and then kneaded with a three-roll mill to prepare a base grease.

[0081] (3) Preparation of grease composition

[0082] The additives listed in Table 1 were blended into the base grease obtained above at the ratios shown in Table 2 (the numbers in the table are mass % based on the total mass of the composition), additional base oil was added so as to give a worked cone penetration as shown in Table 2, and the mixture was dispersed using a three-roll mill, thereby obtaining grease compositions of Examples and Comparative Examples having a worked cone penetration as shown in Table 2.

[0083] [Table 1]

[0084] Table 1 (a) Compounds with phosphate moieties

[0085] Chemical name Manufacturer Product Name / Item a1 Trioxyethylene alkyl (12-15) ether phosphate *1 Dongbang Chemical Phosphanol RS-410 a1 Nonadiene alkyl (12-15) ether phosphate*1 Dongbang Chemical Phosphanol RS-710 a1 Trioxyethylene stearyl ether phosphate Dongbang Chemical Phosphanol RL-310 a1 Tetraoxyethylene lauryl ether phosphate Dongbang Chemical Phosphanol RD-510Y a2 Isopropyl tri(dioctyl pyrophosphate) titanate Ajinomoto PLENACT 38S a2 Diisopropyl bis(dioctyl pyrophosphate) titanate Ajinomoto PLENACT 338X a1 Phosphate Kusumoto Kasei Disparlon DA-375 a1 Polyoxyethylene lauryl ether phosphate metal salt Katsuta Chemical OR-40 For comparison Phosphate CNF Prince HD CNF For comparison Isopropyl bis(N-aminoethyl-aminoethyl) titanate Ajinomoto PLENACT KR44 For comparison Aluminum acetoalkoxyisopropionate Ajinomoto PLENACT AL-M For comparison Polyoxyethylene alkyl ether Sanyo Chemical EMULMIN 40 For comparison Polyether acid, polyamine Kusumoto Kasei Disparlon DA-234 For comparison Tricresyl phosphate TCP

[0086] *1 The number in parentheses after "alkyl" indicates the number of carbon atoms in the alkyl group.

[0087] 2. Evaluation of grease composition

[0088] The EP properties of the grease composition prepared above were evaluated by a high-speed four-ball load bearing capacity test (Shell four-ball test) and an SRV test.

[0089] (1) High-speed four-ball load bearing capacity test (Shell four-ball test)

[0090] LNSL and WP were measured according to ASTM D-2596. The sliding speed was 0.56 mm / s. This test was used to evaluate the EP properties caused by rotational motion, point contact, and sliding friction.

[0091] (2) SRV test

[0092] A steel ball (SUJ-2) with a diameter of 10 mm is pressed vertically on a disc with a diameter of 24 mm and a thickness of 7.855 mm. At a test temperature of 25°C, it is reciprocated horizontally at a frequency of 15 Hz, an amplitude of 1 mm, and a speed of 0.03 mm / s. The load applied to the disc is increased from 100 N / min to 1200 N, and the friction coefficient under the specified load is measured. A sharp increase in the friction coefficient (above 0.25) is regarded as a bite, and the load immediately before is regarded as an OK value (the maximum load without a bite). This test is used to evaluate the wear caused by reciprocating motion, point contact, and sliding friction.

[0093] (3) Working cone penetration

[0094] The measurement was conducted in accordance with JIS K 2220 5.7.

[0095] Judgment Criteria

[0096] LNSL: 980N or more○, less than 980N×

[0097] WP: 1960N or more ○, less than 1960N ×

[0098] OK value: 900N or more ○, less than 900N ×

[0099] The results are shown in Table 2.

[0100] [Table 2]

[0101]

Claims

1. A grease composition comprising (a) a compound having a phosphate ester moiety, (b) a base oil and (c) a thickener, The maximum no-seizure load measured according to ASTM D-2596 is 980N or more.

2. The grease composition according to claim 1, wherein The component (a) is contained in an amount of 0.1 to 20% by mass based on the total mass of the composition.

3. The grease composition according to claim 1 or 2, wherein: Component (a) is (a1) a compound represented by the following chemical formula (1), [Chemistry 1] In the formula, R 1 is an alkyl group having 1 to 24 carbon atoms or an aryl group which may have a substituent, A 1 O is an alkyleneoxy group having 2 to 4 carbon atoms, n is an integer of 0 to 30, m is an integer of 1 to 3, and M is a hydrogen atom, an alkali metal, a Group II metal, an ammonium group, or an organic ammonium group.

4. The grease composition according to claim 1 or 2, wherein Component (a) is at least one coupling agent (a2) having a phosphate ester moiety in the molecule selected from the group consisting of (a2-1) silane coupling agents, (a2-2) titanium coupling agents, (a2-3) aluminum coupling agents, and (a2-4) zirconium oxide coupling agents.

5. The grease composition according to claim 1 or 2, wherein: The sintering load measured according to ASTM D-2596 is 1960N or more.

6. Use of the grease composition according to claim 1 or 2 as an extreme pressure anti-wear grease for bearings, gears, automobile parts, industrial machinery parts, etc.

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