Grease composition

Abstract

Provided is a grease composition containing a molybdenum compound represented by general formula (1), a sulfurized olefin, and a base oil. In general formula (1), R1 to R4 each independently represent an alkyl group having 4 to 18 carbon atoms, and X1 to X4 each independently represent an oxygen atom or a sulfur atom. # imgabs0 #

Description

Technical Field The present invention relates to a grease composition having excellent load-bearing characteristics. Background Art

[0001] Various types of greases have been used to lubricate bearings, joints, gears, transmissions, etc. in automobiles, agricultural machinery, industrial machinery, construction machinery, precision machinery, etc. In recent years, with the increase in production and miniaturization of devices and machinery, there is an increasing demand for greases that can properly demonstrate their properties under severe environments such as high loads. For example, Patent Document 1 describes a grease composition containing a base oil, a lithium soap thickener, a metal stearate, a molybdenum dialkyldithiocarbamate sulfide, and a zinc dialkyldithiocarbamate sulfide, which exhibits excellent wear resistance and real machine durability. In addition, Patent Document 2 describes a grease composition containing a lubricating base oil, a urea thickener, a metal dithiocarbamate, and a thiadiazole compound, which can be used for a long time under high temperature and high load. However, the load bearing performance of these grease compositions is still insufficient, and therefore, there is a market demand for the development of a grease composition having a more excellent load bearing property. Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Publication No. 2011-079902 Patent Document 2: Japanese Patent Application Publication No. 2018-009101 Summary of the invention Problems to be solved by the invention Therefore, an object of the present invention is to provide a grease composition having excellent load bearing characteristics. Means of solving problems Therefore, the present inventors have conducted intensive studies and found that a grease composition containing a specific molybdenum compound, a specific sulfur compound and a base oil has excellent load resistance characteristics, thereby completing the present invention. That is, the present invention is a grease composition containing a molybdenum compound represented by the following general formula (1), a sulfurized olefin and a base oil. [Chemistry 1]

[0002] (Where R 1 ~R 4 Each independently represents an alkyl group having 4 to 18 carbon atoms, and X 1 ~X 4 Each independently represents an oxygen atom or a sulfur atom. ) Effects of the Invention According to the present invention, a grease composition having excellent load resistance characteristics can be provided. DETAILED DESCRIPTION The molybdenum compound used in the present invention is represented by the following general formula (1). [Chemistry 2]

[0003] R in the general formula (1) 1 ~R 4 Each independently represents an alkyl group having 4 to 18 carbon atoms. 1 ~R 4 They may be the same or different. Examples of the alkyl group having 4 to 18 carbon atoms include straight-chain alkyl groups such as n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, and n-tetradecyl; and branched-chain alkyl groups such as sec-butyl, isobutyl, sec-pentyl, sec-hexyl, sec-heptyl, sec-octyl, isooctyl, 2-ethylhexyl, sec-nonyl, isononyl, sec-decyl, isodecyl, sec-undecyl, iso-undecyl, sec-dodecyl, iso-dodecyl, sec-tridecyl, iso-tridecyl, sec-tetradecyl, and iso-tetradecyl. From the viewpoint of the load-bearing properties of the obtained grease composition, R 1 ~R 4 Each independently is preferably a linear or branched alkyl group having 4 to 14 carbon atoms, more preferably a linear or branched alkyl group having 8 to 13 carbon atoms, and still more preferably a linear or branched alkyl group having 8 or 13 carbon atoms. X in the general formula (1) 1 ~X 4 Each independently represents an oxygen atom or a sulfur atom. From the viewpoint of the load bearing characteristics of the obtained grease composition, X is preferably 1 ~X 4 2 to 3 of them are sulfur atoms and the rest are oxygen atoms, and more preferably X 1 ~X 4 Two of them are sulfur atoms and the remaining two are oxygen atoms, and most preferably X 1 and X 2 is a sulfur atom and X 3 and X 4 For oxygen atoms. The molybdenum compound used in the present invention may be one or more of the molybdenum compounds represented by the general formula (1). In addition, the molybdenum compound used in the present invention may be a commercially available product or may be produced by a known production method (e.g., the method described in JP-A-51-80825 and JP-A-08-217782). The sulfided olefin used in the present invention may be used without particular limitation as long as it is a sulfide of an olefin, and examples thereof include compounds (sulfides) obtained by sulfiding an olefin having 2 to 20 carbon atoms or dimers thereof. From the viewpoint of the load-bearing characteristics of the obtained grease composition, the sulfided olefin is preferably a sulfide of an olefin having 2 to 20 carbon atoms, and more preferably a sulfide of an olefin having 4 to 12 carbon atoms. In this case, the sulfur content in the sulfided olefin is not particularly limited, but from the viewpoint of the load-bearing characteristics of the obtained grease composition, the sulfur content in the sulfided olefin is preferably 5 to 50% by mass, more preferably 10 to 45% by mass, and further preferably 15 to 40% by mass. In the present invention, the sulfur content in the sulfided olefin is measured by fluorescent X-ray analysis. The base oil (base oil) used in the present invention can be used without particular limitation as long as it is a base oil commonly used in grease, and for example, mineral oil, chemically synthesized base oil, animal and plant base oil, and mixed base oils thereof can be used. Examples of the mineral oil include paraffinic mineral oil, naphthenic mineral oil, etc., and distilled oils, refined oils, or treated oils thereof can also be used. Examples of chemically synthesized base oils include synthetic hydrocarbon base oils, monoesters, diesters, polyol esters, aromatic esters, silicates, polyalkylene glycols, polyphenylene ethers, silicones, fluorine compounds, alkylbenzenes, GTL base oils, etc. Examples of synthetic hydrocarbon base oils include polyalphaolefins obtained by polymerizing or oligomerizing 1-butene, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tetradecene, etc., metallocene polyalphaolefins obtained by polymerizing or oligomerizing them under a metallocene catalyst, or hydrogenated polyalphaolefins obtained by hydrogenating them, etc. Examples of diesters include diesters obtained by forming dibasic acids such as glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid with alcohols such as hexanol, 2-ethylhexanol, octanol, decanol, dodecanol, and tridecanol, etc. Examples of polyol esters include esters formed from polyols such as neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, and tripentaerythritol and fatty acids such as caproic acid, caprylic acid, 2-ethylhexanoic acid, lauric acid, capric acid, myristic acid, palmitic acid, stearic acid, and oleic acid. Examples of aromatic esters include esters of aromatic compounds such as phthalic acid, isophthalic acid, trimellitic acid, and pyromellitic acid and alcohols. Examples of the animal and plant-based oils include vegetable oils and fats such as castor oil, olive oil, cocoa butter, sesame oil, rice bran oil, safflower oil, soybean oil, camellia oil, corn oil, rapeseed oil, palm oil, palm kernel oil, sunflower oil, cottonseed oil, and coconut oil; and animal oils and fats such as beef tallow, lard, milk fat, fish oil, and whale oil. In the present invention, from the viewpoint of the load resistance characteristics of the obtained grease composition, it is preferred to use a base oil containing at least one selected from mineral oils and chemically synthesized base oils, more preferably to use a base oil containing at least one selected from paraffinic mineral oils, naphthenic mineral oils and synthetic hydrocarbon base oils, and even more preferably to use a base oil containing at least one selected from paraffinic mineral oils, naphthenic mineral oils, polyα-olefins and metallocene polyα-olefins. In the present invention, the viscosity of the base oil used is not particularly limited and can be appropriately adjusted according to the purpose. However, from the viewpoint of the load resistance characteristics of the obtained grease composition, for example, a base oil having a 40° C. dynamic viscosity of 20 to 700 cSt is preferably used, a base oil having a 40° C. dynamic viscosity of 40 to 600 cSt is more preferably used, and a base oil having a 40° C. dynamic viscosity of 50 to 500 cSt is further preferably used. In the present invention, the viscosity of the base oil when two or more base oils are used refers to the viscosity of a mixed base oil obtained by mixing two or more base oils. In addition, in the present invention, from the viewpoint of load resistance, wear resistance at high temperature and corrosion resistance of the obtained grease composition, the base oil preferably further contains at least one aromatic ester selected from trimellitic acid ester and pyromellitic acid ester, and more preferably contains at least one selected from paraffinic mineral oil, naphthenic mineral oil and synthetic hydrocarbon base oil and at least one aromatic ester selected from trimellitic acid ester and pyromellitic acid ester. Examples of trimellitic acid ester include monoesters, diesters and triesters of trimellitic acid and alcohols having 4 to 18 carbon atoms, and examples of pyromellitic acid ester include monoesters, diesters, triesters and tetraesters of pyromellitic acid and alcohols having 4 to 18 carbon atoms. Among them, from the viewpoint of load resistance, wear resistance at high temperature and corrosion resistance of the obtained grease composition, it is preferred to use at least one selected from the triester formed by trimellitic acid and an alcohol having 4 to 18 carbon atoms and the tetraester formed by pyromellitic acid and an alcohol having 4 to 18 carbon atoms as the aromatic ester, and it is more preferred to use the triester formed by trimellitic acid and an alcohol having 4 to 18 carbon atoms. When the base oil used in the present invention contains at least one selected from paraffinic mineral oils, naphthenic mineral oils and synthetic hydrocarbon base oils and at least one aromatic ester selected from trimellitic acid esters and pyromellitic acid esters, the ratio of the content of the at least one selected from paraffinic mineral oils, naphthenic mineral oils and synthetic hydrocarbon base oils to the content of the at least one aromatic ester selected from trimellitic acid esters and pyromellitic acid esters is not particularly limited and can be adjusted according to the purpose. From the viewpoint of the load resistance, wear resistance at high temperatures and corrosion resistance of the obtained grease composition, the ratio of the content of the at least one selected from paraffinic mineral oils, naphthenic mineral oils and synthetic hydrocarbon base oils to the content of the at least one aromatic ester selected from trimellitic acid esters and pyromellitic acid esters is preferably 50:50 to 99:1, more preferably 70:30 to 98:2, and even more preferably 80:20 to 97:3 in terms of mass ratio. The grease composition of the present invention is a grease composition containing the above-mentioned molybdenum compound, a sulfurized olefin and a base oil. The content of the molybdenum compound in the grease composition of the present invention is not particularly limited and can be adjusted according to the purpose, but from the viewpoint of load resistance characteristics, the content of the molybdenum compound is preferably 0.10 to 20% by mass, more preferably 0.20 to 15% by mass, and even more preferably 0.30 to 10% by mass relative to the total amount of the grease composition. The content of the olefin sulfide in the grease composition of the present invention is not particularly limited and can be adjusted according to the purpose, but from the viewpoint of load resistance characteristics, the content of the olefin sulfide is preferably 0.10 to 20% by mass, more preferably 0.20 to 15% by mass, and even more preferably 0.30 to 10% by mass relative to the total amount of the grease composition. The ratio of the content of the molybdenum compound to the content of the sulfided olefin in the grease composition of the present invention is not particularly limited and can be adjusted according to the purpose. However, from the viewpoint of load resistance characteristics, the ratio of the content of the molybdenum compound to the content of the sulfided olefin in the grease composition is preferably 0.1:10 to 10:0.1 in terms of mass ratio, more preferably 1:10 to 10:1, and even more preferably 1:5 to 5:1. The content of the base oil in the grease composition of the present invention is not particularly limited and can be adjusted according to the purpose, but from the viewpoint of load resistance characteristics, the content of the base oil is preferably 50 to 99% by mass, more preferably 60 to 98% by mass, and even more preferably 70 to 97% by mass relative to the total amount of the grease composition. The grease composition of the present invention may contain other additives in addition to the above-mentioned molybdenum compound, olefin sulfide, and base oil, depending on the purpose. Examples of additives that may be contained in the grease composition of the present invention include thickeners, antiwear agents (excluding the molybdenum compound represented by the general formula (1)), extreme pressure additives (excluding olefin sulfide), friction modifiers, corrosion inhibitors (corrosion inhibitors), detergent dispersants (detergents), antioxidants, rust inhibitors, viscosity index improvers, oiliness agents, colorants, surfactants, metal inert agents, and the like, and one or more of these may be used. As a thickener, any known thickener may be used without particular limitation, and examples thereof include lithium soap, lithium complex soap, calcium soap, calcium complex soap, urea compounds, and the like, and one or more of them may be used. Among them, from the viewpoint of the load resistance characteristics, wear resistance at high temperature, and corrosion resistance of the obtained grease composition, it is preferred to use at least one thickener selected from lithium soap, lithium complex soap, and urea compounds, and it is more preferred to use at least one thickener selected from lithium soap and lithium complex soap. As lithium soap, lithium salts of monocarboxylic acids having 12 to 24 carbon atoms, etc., may be mentioned. As lithium complex soap, a complex formed by combining a lithium salt of a monocarboxylic acid having 12 to 24 carbon atoms and a lithium salt of a dicarboxylic acid having 2 to 12 carbon atoms, etc. may be mentioned. Examples of urea compounds include aliphatic ureas formed from a reaction product of an aliphatic amine having 4 to 24 carbon atoms and a diisocyanate, alicyclic ureas formed from a reaction product of an alicyclic amine having 6 to 24 carbon atoms and a diisocyanate, aromatic ureas formed from a reaction product of an aromatic amine having 6 to 24 carbon atoms and a diisocyanate, and mixtures thereof. When the grease composition of the present invention contains a thickener, the content of the thickener is not particularly limited and can be adjusted according to the purpose, but from the viewpoint of the load resistance of the obtained grease composition, the content of the thickener is preferably 1.0 to 30% by mass, more preferably 2.0 to 20% by mass, and even more preferably 3.0 to 15% by mass relative to the total amount of the grease composition. In the present invention, from the viewpoint of load resistance, wear resistance at high temperatures and corrosion resistance of the obtained grease composition, it is preferred that 1.0 to 30% by mass of at least one thickener selected from lithium soaps, lithium complex soaps and urea compounds be contained, more preferably 2.0 to 20% by mass, and even more preferably 3.0 to 15% by mass, relative to the total amount of the grease composition. As the anti-wear agent, any known anti-wear agent can be used without particular limitation, and examples thereof include zinc dialkyl dithiophosphate, molybdenum disulfide, amine molybdate, polytetrafluoroethylene, chlorinated paraffin, tungsten disulfide, selenium disulfide, graphite fluoride, zinc oxide, etc., and one or more of them can be used. Among them, zinc dialkyl dithiophosphate includes zinc dialkyl dithiophosphate having an alkyl group with 4 to 22 carbon atoms, etc. When the grease composition of the present invention contains an anti-wear agent, the content of the anti-wear agent is not particularly limited and can be adjusted according to the purpose, but from the viewpoint of the load resistance of the obtained grease composition, the content of the anti-wear agent is preferably 0.10 to 10% by mass, more preferably 0.20 to 8.0% by mass, relative to the total amount of the grease composition. In addition, in the present invention, from the viewpoint of the wear resistance and corrosion resistance of the obtained grease composition at high temperatures, it is preferred that the zinc dialkyl dithiophosphate having an alkyl group with 4 to 22 carbon atoms is not contained, or the content thereof is 0.001 to 3.0% by mass relative to the total amount of the grease composition. In the present invention, when the content of the zinc dialkyl dithiophosphate exceeds 3.0% by mass, the wear resistance and corrosion resistance of the obtained grease composition at high temperatures may be reduced. As the extreme pressure additive, any known extreme pressure additive (except sulfided olefins) can be used without particular limitation, and examples thereof include sulfur-based extreme pressure additives such as sulfided fatty acids, thiadiazoles, and thioesters, and phosphorus-based extreme pressure additives such as phosphates, acid phosphates, amine salts of acid phosphates, and phosphites, and one or more of these can be used. Among them, as the phosphate ester, tert-butylbenzene diphenyl phosphate, phenyl (di-tert-butylphenyl) phosphate, and the like can be mentioned. When the grease composition of the present invention contains an extreme pressure additive, the content of the extreme pressure additive is not particularly limited and can be adjusted according to the purpose, but from the viewpoint of the load resistance of the obtained grease composition, the content of the extreme pressure additive is preferably 0.10 to 10% by mass, more preferably 0.20 to 8.0% by mass, relative to the total amount of the grease composition. In addition, in the present invention, from the viewpoint of the wear resistance and corrosion resistance of the obtained grease composition at high temperatures, it is preferred that the phosphate ester is not contained or the content thereof is 0.001 to 3.0% by mass relative to the total amount of the grease composition. In the present invention, when the content of the phosphate ester exceeds 3.0% by mass, the wear resistance and corrosion resistance of the obtained grease composition at high temperatures may be reduced. As the friction modifier, any known friction modifier can be used without particular limitation, and examples thereof include: long-chain fatty acids and their derivatives, aliphatic amines or ethoxylated aliphatic amines, ether amines, alkoxylated ether amines, acylated amines, tertiary amines, aliphatic fatty amides, aliphatic carboxylic acids, aliphatic carboxylic acid esters, polyol esters, aliphatic carboxylic acid ester-amides, imidazolines, acrylate copolymers, and the like, and one or more of them can be used. In the present invention, it is preferable to use an acrylic acid ester copolymer containing units (a) represented by the following general formula (2) and units (b) represented by the following general formula (3) at a molar ratio of 30:70 to 90:10 and having a weight average molecular weight of 5000 to 300,000. [Chemistry 3]

[0004] R in the general formula (2) 5represents an alkyl group having 4 to 18 carbon atoms. Examples of such a group include a linear alkyl group having 4 to 18 carbon atoms, such as butyl, hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl, and a branched alkyl group having 4 to 18 carbon atoms, such as isobutyl, isohexyl, isooctyl, isodecyl, isododecyl, isotetradecyl, isohexadecyl, and isooctadecyl. In general formula (2), R represents an alkyl group having 4 to 18 carbon atoms, such as butyl, hexyl, octyl, decyl, dodecyl, tetradecyl, isohexadecyl, and isooctadecyl. In view of the load resistance, high temperature wear resistance, and corrosion resistance of the obtained grease composition, R in general formula (2) 5 It is preferably a linear or branched alkyl group having 6 to 16 carbon atoms, and more preferably a linear alkyl group having 8 to 16 carbon atoms. [Chemistry 4]

[0005] R in the general formula (3) 6 represents an alkylene group having 2 to 4 carbon atoms. Examples of such a group include ethylene, propylene, isopropylene, butylene, and isobutylene. In particular, from the viewpoint of the load resistance, wear resistance at high temperatures, and corrosion resistance of the obtained grease composition, R in the general formula (3) is preferably 6 Preferred is ethylene, propylene or isopropylene, and more preferred is ethylene. In the present invention, the acrylate copolymer that can be suitably used as a friction modifier is an acrylate copolymer containing the unit (a) represented by the general formula (2) and the unit (b) represented by the general formula (3) in a molar ratio of 30:70 to 90:10. Among them, from the viewpoint of the load resistance, wear resistance at high temperature and corrosion resistance of the obtained grease composition, the acrylate copolymer containing the unit (a) represented by the general formula (2) and the unit (b) represented by the general formula (3) in a molar ratio of 35:65 to 80:20 is preferred, and the acrylate copolymer containing the unit (a) represented by the general formula (2) and the unit (b) represented by the general formula (3) in a molar ratio of 40:60 to 70:30 is more preferred. In addition, from the viewpoint of the load resistance, wear resistance at high temperatures and corrosion resistance of the obtained grease composition, the total amount of the unit (a) represented by the general formula (2) and the unit (b) represented by the general formula (3) in all the units constituting the acrylic ester copolymer is preferably 50 to 100%, more preferably 75 to 100%, further preferably 90 to 100%, and particularly preferably 100%. In the present invention, the acrylate copolymer that can be suitably used as a friction modifier is an acrylate copolymer having the above structure and a weight average molecular weight of 5000 to 300000. Among them, from the viewpoint of load resistance, wear resistance at high temperature and corrosion resistance of the obtained grease composition, an acrylate copolymer having a weight average molecular weight of 10000 to 250000 is preferred, and an acrylate copolymer having a weight average molecular weight of 15000 to 200000 is more preferred. The above-mentioned acrylic ester copolymer can be produced by a known production method using a monomer that can be converted into the unit (a) represented by the general formula (2) by a polymerization reaction and a monomer that can be converted into the unit (b) represented by the general formula (3) by a polymerization reaction. As such a method, for example, it can be produced by the following method: "Use n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, isohexyl acrylate, n-heptyl acrylate, isoheptyl acrylate, n-octyl acrylate, isooctyl acrylate, ethylhexyl acrylate, n-nonyl acrylate, isononyl acrylate, n-decyl acrylate, isodecyl acrylate, n-dodecyl acrylate, isododecyl acrylate, n-tetradecyl acrylate, isotetradecyl acrylate, n-hexadecyl acrylate, isohexadecyl acrylate, n-octadecyl acrylate, isooctadecyl acrylate, ethylhexyl acrylate, n-nonyl acrylate, isononyl acrylate, n-decyl acrylate, isodecyl acrylate, n-dodecyl acrylate, isododecyl acrylate, n-tetradecyl acrylate, isotetradecyl acrylate, n-hexadecyl acrylate, isohexadecyl acrylate, n-octadecyl acrylate, isooctadecyl acrylate The method comprises reacting "one or more acrylic acid ester monomers having an alkyl group with 4 to 18 carbon atoms, such as acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, etc., as a monomer which can be converted into the unit (b) represented by the general formula (3) in the copolymer by polymerization reaction" (optionally using a reaction initiator, a catalyst, a solvent, etc. as required) at room temperature to 150° C. for 10 minutes to 48 hours in an amount such that the molar ratio of the two is 30:70 to 90:10, thereby achieving a weight average molecular weight of the obtained acrylic acid ester copolymer of 5,000 to 300,000. When the grease composition of the present invention contains a friction modifier, the content of the friction modifier is not particularly limited and can be adjusted according to the purpose, but from the viewpoint of the load resistance of the obtained grease composition, the content of the friction modifier is preferably 0.10 to 10% by mass, more preferably 0.20 to 8.0% by mass, relative to the total amount of the grease composition. In the present invention, from the viewpoint of load resistance, wear resistance at high temperatures and corrosion resistance of the obtained grease composition, the acrylic acid ester copolymer is preferably contained in an amount of 0.10 to 10% by mass, more preferably 0.20 to 8.0% by mass, and even more preferably 0.30 to 6.0% by mass, relative to the total amount of the grease composition. As the corrosion inhibitor, any known corrosion inhibitor may be used without particular limitation, and for example, triazine compounds, benzotriazole compounds, tolyltriazole compounds, benzimidazole compounds, etc. may be used, and one or more of them may be used. Among them, from the viewpoint of the load resistance, wear resistance at high temperature and corrosion resistance of the obtained grease composition, it is preferred to use one or more corrosion inhibitors selected from triazine compounds and benzotriazole compounds. Among them, examples of benzotriazole compounds include 1,2,3-benzotriazole, 1,H-benzotriazole, 4-methyl-1,H-benzotriazole, 4-carboxy-1,H-benzotriazole, sodium tolyltriazole, 5-methyl-1,H-benzotriazole, benzotriazole butyl ether, silver benzotriazole, 5-chloro-1,H-benzotriazole, 1-chloro-benzotriazole, 1-di(octyl)aminomethyl-benzotriazole, 2,3-dihydroxypropyl-benzotriazole, 1,2-dicarboxyethyl-benzotriazole, (octyl)aminomethyl-benzotriazole, and the like. When the grease composition of the present invention contains a corrosion inhibitor, the content of the corrosion inhibitor is not particularly limited and can be adjusted according to the purpose. However, from the viewpoint of the load resistance of the obtained grease composition, the content of the corrosion inhibitor is preferably 0.0001 to 1.0 mass %, more preferably 0.0002 to 0.50 mass % relative to the total amount of the grease composition. In the present invention, from the viewpoint of load resistance, wear resistance at high temperatures and corrosion resistance of the obtained grease composition, it is preferred that 0.0001 to 1.0 mass % of one or more corrosion inhibitors selected from triazine compounds and benzotriazole compounds be contained, and more preferably 0.0002 to 0.50 mass % be contained, relative to the total amount of the grease composition. As the detergent dispersant, any known detergent dispersant can be used without particular limitation, and examples thereof include alkaline earth metal detergents such as sulfonates, phenolates, salicylates, phosphonates, fatty acids, etc. of alkaline earth metals such as magnesium, calcium, and barium; succinimide-type dispersants obtained by a condensation reaction of alkenyl succinic anhydride and a polyamine compound; succinate-type dispersants obtained by a condensation reaction of alkenyl succinic anhydride and a polyol compound; succinate-amide-type dispersants obtained by a condensation reaction of alkenyl succinic anhydride and an alkanolamine; Mannich base-based dispersants obtained by condensing alkylphenols and polyamines with formaldehyde; and boric acid-modified products thereof. Among them, from the viewpoint of the load resistance, wear resistance and corrosion resistance at high temperature of the obtained grease composition, it is preferred to contain at least one detergent dispersant selected from basic calcium sulfonate, basic calcium salicylate, basic fatty acid calcium, basic magnesium sulfonate, basic magnesium salicylate and basic fatty acid magnesium, and it is more preferred to contain at least one detergent dispersant selected from basic calcium sulfonate and basic calcium salicylate. Among them, as the alkaline earth metal detergent, from the viewpoint of the load resistance, wear resistance and corrosion resistance at high temperature of the obtained grease composition, an alkaline earth metal detergent having a base value of 50 to 600 mgKOH / g is preferred, an alkaline earth metal detergent having a base value of 100 to 550 mgKOH / g is more preferred, and an alkaline earth metal detergent having a base value of 150 to 500 mgKOH / g is further preferred. In the present invention, from the viewpoint of improving the load resistance, wear resistance at high temperatures and corrosion resistance of the obtained grease composition, it is preferred to use at least one basic calcium salt selected from basic calcium sulfonates having a base value of 50 to 600 mgKOH / g and basic calcium salicylate having a base value of 50 to 600 mgKOH / g, more preferably at least one basic calcium salt selected from basic calcium sulfonates having a base value of 100 to 550 mgKOH / g and basic calcium salicylate having a base value of 100 to 550 mKOH / g, and even more preferably at least one basic calcium salt selected from basic calcium sulfonates having a base value of 150 to 500 mgKOH / g and basic calcium salicylate having a base value of 150 to 500 mgKOH / g. When the grease composition of the present invention contains a detergent dispersant, the content of the detergent dispersant is not particularly limited and can be adjusted according to the purpose, but from the viewpoint of the load resistance of the obtained grease composition, the content of the detergent dispersant is preferably 0.10 to 10% by mass, more preferably 0.20 to 8.0% by mass, relative to the total amount of the grease composition. In the present invention, from the viewpoint of load resistance, wear resistance at high temperatures and corrosion resistance of the obtained grease composition, it is preferred that 0.10 to 10% by mass of at least one detergent dispersant selected from basic calcium sulfonates and basic calcium salicylate be contained, with respect to the total amount of the grease composition, 0.20 to 8.0% by mass is more preferred, and 0.30 to 6.0% by mass is further preferred. As antioxidants, for example, amine antioxidants, phenolic antioxidants, phenothiazine antioxidants, phosphite antioxidants, etc. can be mentioned, and one or more of them can be used. When the grease composition of the present invention contains an antioxidant, the content of the antioxidant is not particularly limited and can be adjusted according to the purpose. For example, 0.10 to 10% by mass of the antioxidant can be contained relative to the total amount of the grease composition. Examples of rust inhibitors include calcium salts of oxidized paraffin, magnesium salts of oxidized paraffin, alkali metal salts of tallow fatty acids, alkaline earth metal salts or amine salts, alkenyl succinic acid or alkenyl succinic acid half esters (the molecular weight of the alkenyl group is about 100 to 300), sorbitan monoesters, pentaerythritol monoesters, glycerol monoesters, nonylphenol ethoxylates, lanolin fatty acid esters, lanolin fatty acid calcium salts, and the like. One or more of these can be used. When the grease composition of the present invention contains a rust inhibitor, the content of the rust inhibitor is not particularly limited and can be adjusted according to the purpose. For example, the rust inhibitor can be contained in an amount of 0.10 to 10% by mass relative to the total amount of the grease composition. In the present invention, from the viewpoint of load resistance, wear resistance at high temperature and corrosion resistance of the obtained grease composition, it is preferred to contain monoglyceride as a rust inhibitor, more preferably at least one selected from glyceryl monooleate, glyceryl monostearate and glyceryl monolaurate, and even more preferably glyceryl monooleate. In this case, from the viewpoint of load resistance, wear resistance at high temperature and corrosion resistance of the obtained grease composition, it is preferred to contain 0.20 to 5.0% by mass of monoglyceride, more preferably 0.50 to 3.0% by mass of monoglyceride relative to the total amount of the grease composition. Examples of viscosity index improvers include polymethacrylate (C1-18) alkyl esters, acrylate (C1-18) alkyl ester / methacrylate (C1-18) alkyl ester copolymers, diethylaminoethyl methacrylate / methacrylate (C1-18) alkyl ester copolymers, ethylene / methacrylate (C1-18) alkyl ester copolymers, polyisobutylene, polyalkylstyrene, ethylene / propylene copolymers, styrene / maleate copolymers, styrene / maleamide copolymers, styrene / butadiene hydrogenated copolymers, styrene / isoprene copolymers, and the like. One or more of these can be used. When the grease composition of the present invention contains a viscosity index improver, the content of the viscosity index improver is not particularly limited and can be adjusted according to the purpose. For example, the viscosity index improver can be contained in an amount of 0.10 to 10% by mass relative to the total amount of the grease composition. Examples of oiliness improvers include fatty acids, oils and fats or hydrogenated or partially saponified products thereof, epoxidized esters, polycondensates of hydroxystearic acid or esters of the polycondensates and fatty acids, higher alcohols, higher amides, glycerol esters, polyglycerol esters, polyglycerol ethers, and α-olefin oxide adducts of these compounds, and one or more of these can be used. When the grease composition of the present invention contains an oiliness improver, the content of the oiliness improver is not particularly limited and can be adjusted according to the purpose. For example, the oiliness improver can be contained in an amount of 0.10 to 20% by mass relative to the total amount of the grease composition. The grease composition of the present invention can be used without particular limitation as long as it is used for the purpose of using grease, and can be used, for example, for various sliding parts such as bearings, joints, gears, transmission devices, etc. in railways, airplanes, ships, home appliances, automobiles, production equipment, machine tools, construction machinery, household appliances, precision machinery, etc. Example Hereinafter, the present invention will be described in more detail by way of examples. In the following examples, % is based on mass unless otherwise specified. The molybdenum compound, sulfurized olefin, acrylic ester copolymer, extreme pressure additive, corrosion inhibitor, rust inhibitor, detergent dispersant, antiwear agent and base oil used in the present invention are as follows. <Molybdenum compounds> Molybdenum compound 1: represented by the general formula (1), wherein R 1 ~R 4 For butyl, X 1 and X 2 is a sulfur atom, X 3 and X 4 Molybdenum compounds with oxygen atoms Molybdenum compound 2: represented by the general formula (1), wherein R 1 and R 2 is 2-ethylhexyl, R 3 and R 4 isotridecyl, X 1 and X 2 is a sulfur atom, X 3 and X 4 Molybdenum compounds with oxygen atoms <Sulfurized olefins> Sulfurized olefin 1: Sulfide of an olefin having 8 carbon atoms (sulfur content: 30% by mass) <Acrylate Copolymer> Acrylate copolymer 1: R in the general formula (2) 5 The unit (a) is a dodecyl group and R in the general formula (3) 6An acrylic ester copolymer composed of ethylene units (b), wherein the molar ratio of units (a) to units (b) is 60:40 and the weight average molecular weight is 150,000 <Extreme pressure additives> Extreme pressure additive 1: tert-butylbenzene diphenyl phosphate <Corrosion inhibitor> Anticorrosive agent 1: Methyl-1H-benzotriazole <Rust inhibitor> Rust inhibitor 1: glycerol monooleate <Cleaning dispersant> Cleaning dispersant 1: basic calcium sulfonate with a base value of 400 mgKOH / g Cleaning dispersant 2: basic calcium salicylate with a base value of 170 mgKOH / g <Anti-wear agent> Antiwear agent 1: diisotridecylamine molybdate Antiwear agent 2: didodecyl zinc dithiophosphate <Base oil> Base oil 1: A mixture of 90% by mass of a naphthenic mineral oil (base oil) having a 40°C dynamic viscosity of 130 cSt and 10% by mass of 12-hydroxystearate lithium (thickener) Base oil 2: Tri(2-ethylhexyl) trimellitate Base oil 3: A mixture of 88% by mass of a poly-α-olefin (base oil) with a 40°C dynamic viscosity of 65 cSt and 12% by mass of lithium 12-hydroxystearate (thickener) Base oil 4: A mixture of 88% by mass of a mixed base oil having a 40°C dynamic viscosity of 320 cSt (a mixed base oil composed of 14.5% by mass of a polyα-olefin having a 40°C dynamic viscosity of 18 cSt and 85.5% by mass of a metallocene polyα-olefin having a 40°C dynamic viscosity of 602 cSt) and 12% by mass of lithium 12-hydroxystearate (thickener) Base oil 5: A mixture of 88% by mass of a mixed base oil having a 40°C dynamic viscosity of 460 cSt (a mixed base oil composed of 6.0% by mass of a polyα-olefin having a 40°C dynamic viscosity of 18 cSt and 94.0% by mass of a metallocene polyα-olefin having a 40°C dynamic viscosity of 602 cSt) and 12% by mass of lithium 12-hydroxystearate (thickener) <Manufacturing of Grease Composition 1> The grease compositions of Examples 1 to 6 and Comparative Examples 1 to 10 were prepared by mixing a molybdenum compound, a sulfurized olefin, an acrylate copolymer, an extreme pressure additive, a corrosion inhibitor, a detergent dispersant, an antiwear agent and a base oil in the mass ratios shown in Tables 1 to 3. <Load resistance test and load resistance characteristic evaluation> Based on the method described in ASTM D2596, each grease composition manufactured was subjected to a load resistance test under a high-load environment. Specifically, a shell-type high-speed four-ball tester (manufactured by Kobelco) was used. Under the conditions of a rotation speed of 1770 rpm and 27±8°C, the initial load was set to 100 kgf, and the load was increased by 10 kgf each time. The load at which the test balls melted and bonded to each other was then measured as the tolerance load. In addition, based on the measured tolerance load, the load resistance characteristics were evaluated based on the following evaluation criteria. The evaluation results are shown in Tables 1 to 3. Evaluation criteria for load bearing characteristics ◎: Load resistance is 450kgf or more ○: Load resistance is 400 kgf or more and less than 450 kgf △: Load tolerance is 320kgf or more and less than 400kgf ×: Load tolerance is less than 320kgf

[0006] [Table 1]

[0007] [Table 2]

[0008] [Table 3]

[0009] <Manufacturing of Grease Composition 2> The grease compositions of Examples 7 to 13 were prepared by mixing a molybdenum compound, a sulfurized olefin, an acrylate copolymer, an extreme pressure additive, a corrosion inhibitor, a detergent dispersant, an antiwear agent, and a base oil in the mass ratios shown in Table 4. <Load resistance test and load resistance characteristic evaluation> Based on the method described in ASTM D2596, each grease composition manufactured was subjected to a load resistance test under a high-load environment. Specifically, a shell-type high-speed four-ball tester (manufactured by Kobelco) was used. Under the conditions of a rotation speed of 1770 rpm and 27±8°C, the initial load was set to 100 kgf, and the load was increased by 10 kgf each time. The load at which the test balls melted and bonded to each other was then measured as the tolerance load. In addition, based on the measured tolerance load, the load resistance characteristics were evaluated based on the following evaluation criteria. The measurement results and evaluation results are shown in Table 4. Evaluation criteria for load bearing characteristics ◎: Load resistance is 450kgf or more ○: Load resistance is 400 kgf or more and less than 450 kgf △: Load tolerance is 320kgf or more and less than 400kgf ×: Load tolerance is less than 320kgf <Wear resistance test and wear resistance evaluation> Based on ASTM D2266, each of the manufactured grease compositions was subjected to a wear resistance test under a high-load environment. Specifically, a shell-type high-speed four-ball tester (manufactured by Kobelco) was used to measure the wear scar diameter after the test under the conditions of 75±2°C, a rotation speed of 1200 rpm, and a test time of 60 minutes. In addition, based on the measured wear scar diameter, the wear resistance characteristics were evaluated according to the following evaluation criteria. The measurement results and evaluation results are shown in Table 4. Evaluation criteria for wear resistance ◎: Wear scar diameter is less than 0.45mm ○: Wear scar diameter is 0.45 mm or more and less than 0.50 mm △: Wear scar diameter is 0.50 mm or more and less than 0.65 mm ×: Wear scar diameter is 0.65 mm or more <Corrosion resistance test and corrosion resistance evaluation> Based on ASTM D4048, the corrosion resistance of each manufactured grease composition was evaluated. Specifically, the cleaned copper plate was immersed in the grease, kept at 100°C for 24 hours, and then the copper plate was taken out and washed, and then compared with the copper plate corrosion standard plate to determine which classification 1a to 4c the color tone of each immersed copper plate corresponds to. In addition, based on each judgment result, the corrosion resistance was evaluated according to the following evaluation criteria. Each judgment result and evaluation result are shown in Table 4. Corrosion resistance evaluation standard ◎: Judgment result is 1a~1b ○: The judgment result is 2a to 2e △: The judgment result is 3a to 3b ×: The judgment result is 4a to 4c

[0010] [Table 4]

[0011] <Manufacturing of Grease Composition 3> The grease compositions of Examples 14 to 18 were prepared by mixing a molybdenum compound, a sulfurized olefin, an acrylate copolymer, an extreme pressure additive, a corrosion inhibitor, a rust inhibitor, a detergent dispersant, and a base oil in the mass ratios shown in Table 5. <Load resistance test and load resistance characteristic evaluation> Based on the method described in ASTM D2596, each grease composition manufactured was subjected to a load resistance test under a high-load environment. Specifically, a shell-type high-speed four-ball tester (manufactured by Kobelco) was used. Under the conditions of a rotation speed of 1770 rpm and 27±8°C, the initial load was set to 100 kgf, and the load was increased by 10 kgf each time. The load at which the test balls melted and bonded to each other was then measured as the tolerance load. In addition, based on the measured tolerance load, the load resistance characteristics were evaluated based on the following evaluation criteria. The measurement results and evaluation results are shown in Table 5. Evaluation criteria for load bearing characteristics ◎: Load resistance is 450kgf or more ○: Load resistance is 400 kgf or more and less than 450 kgf △: Load tolerance is 320kgf or more and less than 400kgf ×: Load tolerance is less than 320kgf <Wear resistance test and wear resistance evaluation> Based on ASTM D2266, each of the manufactured grease compositions was subjected to a wear resistance test under a high-load environment. Specifically, a shell-type high-speed four-ball tester (manufactured by Kobelco) was used to measure the wear scar diameter after the test under the conditions of 75±2°C, a rotation speed of 1200 rpm, and a test time of 60 minutes. In addition, based on the measured wear scar diameter, the wear resistance characteristics were evaluated according to the following evaluation criteria. The measurement results and evaluation results are shown in Table 5. Evaluation criteria for wear resistance ◎: Wear scar diameter is less than 0.45mm ○: Wear scar diameter is 0.45 mm or more and less than 0.50 mm △: Wear scar diameter is 0.50 mm or more and less than 0.65 mm ×: Wear scar diameter is 0.65 mm or more <Corrosion resistance test and corrosion resistance evaluation> Based on ASTM D4048, the corrosion resistance of each manufactured grease composition was evaluated. Specifically, the cleaned copper plate was immersed in the grease, kept at 100°C for 24 hours, and then the copper plate was taken out and washed, and then compared with the copper plate corrosion standard plate to determine which classification 1a to 4c the color tone of each immersed copper plate corresponds to. In addition, based on each judgment result, the corrosion resistance was evaluated according to the following evaluation criteria. Each judgment result and evaluation result are shown in Table 5. Corrosion resistance evaluation standard ◎: Judgment result is 1a~1b ○: The judgment result is 2a to 2e △: The judgment result is 3a to 3b ×: The judgment result is 4a to 4c

[0012] [Table 5]

[0013] The grease composition of the present invention exhibits excellent load resistance characteristics by containing a molybdenum compound represented by the general formula (1), a sulfurized olefin, and a base oil. In addition, by further containing an acrylic ester copolymer, an anticorrosive agent, etc., it is shown that a grease composition excellent in all of load resistance, wear resistance at high temperatures, and corrosion resistance can be obtained.

Claims

1. A grease composition comprising a molybdenum compound represented by the following general formula (1), a sulfurized olefin and a base oil, In the formula, R 1 ~R 4 Each independently represents an alkyl group having 4 to 18 carbon atoms, and X 1 ~X 4 Each independently represents an oxygen atom or a sulfur atom.

2. The grease composition according to claim 1, wherein The sulfided olefin is a sulfide of an olefin having 2 to 20 carbon atoms, and the sulfur content of the sulfided olefin is 5 to 50% by mass.

3. The grease composition according to claim 1 or 2, further comprising an acrylate copolymer, wherein the acrylate copolymer comprises a unit (a) represented by the following general formula (2) and a unit (b) represented by the following general formula (3) in a molar ratio of 30:70 to 90:10, and the weight average molecular weight of the acrylate copolymer is 5,000 to 300,000. In the formula, R 5 represents an alkyl group having 4 to 18 carbon atoms, In the formula, R 6 It represents an alkylene group having 2 to 4 carbon atoms.

4. The grease composition according to claim 1 or 2, further comprising at least one corrosion inhibitor selected from the group consisting of triazine compounds and benzotriazole compounds.

5. The grease composition according to claim 1 or 2, further comprising at least one detergent dispersant selected from the group consisting of basic calcium sulfonate, basic calcium salicylate, basic fatty acid calcium, basic magnesium sulfonate, basic magnesium salicylate and basic fatty acid magnesium.

6. The grease composition according to claim 1 or 2, wherein: The base oil contains at least one selected from paraffinic mineral oil, naphthenic mineral oil and synthetic hydrocarbon base oil.

7. The grease composition according to claim 6, wherein The base oil further contains at least one aromatic ester selected from trimellitic acid ester and pyromellitic acid ester.

8. The grease composition according to claim 1 or 2, further comprising at least one thickener selected from the group consisting of lithium soaps, lithium complex soaps and urea compounds.

Images