Grease composition

Abstract

To provide a grease composition that achieves a low rotation torque value and improved lubrication life.SOLUTION: A grease composition comprises a base oil and a diurea compound represented by R1NHCONHR2NHCONHR3 (wherein R1 and R3 each independently represent a monovalent alicyclic hydrocarbon group or a monovalent aliphatic hydrocarbon group; R2 represents a divalent aromatic hydrocarbon group with 6 to 15 carbon atoms), wherein, when a worked penetration of the grease composition is P and a rotation torque value of the grease composition at 25°C is T (mN*m), a ratio T / P is less than 0.019.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In recent years, in order to meet the needs for energy saving and high efficiency, there has been a demand for a characteristic of bearing grease that can reduce bearing rotation torque. For example, Patent Document 1 proposes a rolling bearing filled with a grease composition containing a viscosity index improver such as polyisobutylene as a rolling bearing with improved low torque properties. However, the grease composition filled in the rolling bearing of Patent Document 1 has poor heat resistance and insufficient lubrication life.

[0003] Furthermore, Patent Document 2 describes a grease composition that contains a diurea compound and cellulose fibers and that can achieve lower torque than conventional grease compositions while suppressing deterioration in heat resistance and long-term lubricating properties.

[0004] On the other hand, greases with high worked penetration and softness have been conventionally considered to have high resistance and are disadvantageous in terms of torque. For example, Non-Patent Document 1 suggests that if the grease is soft and is not sufficiently removed from the lubricated parts, and even if it is removed, it continues to move back to the lubricated parts, the stirring resistance is high and the friction torque is high for a long time. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-275037 A [Patent Document 2] JP 2017-200981 A [Non-patent literature]

[0006] [Non-Patent Document 1] "Fundamentals and Applications of Lubricating Grease", edited by the Grease Research Group of the Japanese Society of Tribologists, Yokendo, 2007, pp.123-124 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a grease composition which has a small rotational torque value and is capable of improving the lubrication life. [Means for solving the problem]

[0008] As a result of intensive research, the present inventors have discovered that a grease composition containing a base oil and a specific diurea compound has an unexpected property of having a lower rotational torque value relative to worked penetration compared to conventional grease compositions, and have also discovered that the grease composition has a small rotational torque value and an excellent lubrication life, thereby completing the present invention.

[0009] That is, the present invention [1] A base oil and a compound having the following formula (1): R 1 NHCONHR 2 NHCONHR 3 (1) (In the formula, R 1 and R 3 each independently represents a monovalent alicyclic hydrocarbon group or a monovalent aliphatic hydrocarbon group; R 2 represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms. A grease composition containing a diurea compound represented by the formula: a grease composition, in which T / P is less than 0.019, where P is a worked penetration of the grease composition and T (mN m) is a rotational torque value of the grease composition at 25°C; [2] The grease composition according to the above [1], wherein the monovalent alicyclic hydrocarbon group has 4 to 12 carbon atoms and the monovalent aliphatic hydrocarbon group has 6 to 24 carbon atoms. [3] The grease composition according to the above [1] or [2], wherein the monovalent alicyclic hydrocarbon group has 6 to 10 carbon atoms and the monovalent aliphatic hydrocarbon group has 10 to 24 carbon atoms. [4] The grease composition according to any one of the above [1] to [3], wherein the monovalent alicyclic hydrocarbon group has 6 to 8 carbon atoms and the monovalent aliphatic hydrocarbon group has 18 to 22 carbon atoms. [5] R 1 and R 3 The grease composition according to any one of the above [1] to [4], wherein the proportion of monovalent alicyclic hydrocarbon groups is 45 to 65 mol % of the total amount of the above. [6] The grease composition according to any one of the above [1] to [5], wherein the worked penetration P of the grease composition is 200 to 330. [7] The grease composition according to any one of the above [1] to [6], wherein the monovalent aliphatic hydrocarbon group is a behenyl group. [8] The grease composition according to any one of the above [1] to [7], wherein the content of the diurea compound represented by the formula (1) in the grease composition is 8.0 to 14.0 mass%. [9] The kinematic viscosity of the base oil at 40 ° C. is 25 to 140 mm 2 The grease composition according to any one of the above items [1] to [8],

[10] The grease composition according to any one of the above [1] to [9], wherein the base oil contains a synthetic hydrocarbon oil and a synthetic ester oil.

[11] A bearing packed with the grease composition according to any one of [1] to

[10] above. Effect of the Invention

[0010] According to the present invention, there is provided a grease composition which has a small rotational torque value and can improve the lubrication life. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Grease composition> The grease composition according to this embodiment contains a base oil and a specific diurea compound as essential components. The grease composition according to this embodiment will be described in detail below. However, the following description is an example for explaining this embodiment, and is not intended to limit the technical scope of the present invention to only this described range. In this specification, when a numerical range is indicated using "~", the numerical values ​​at both ends are included.

[0012] (Base oil) The base oil is not particularly limited as long as it is a normal base oil used in grease, but examples thereof include mineral oil, synthetic hydrocarbon oil, synthetic ester oil, vegetable oil, animal oil, polyglycol-based synthetic oil, phenyl ether-based synthetic oil, silicone-based synthetic oil, and fluorine-based synthetic oil. Among them, from the viewpoint of lubrication life, it is preferable to contain one or more selected from the group consisting of synthetic hydrocarbon oil, synthetic ester oil, mineral oil, and phenyl ether-based synthetic oil, and it is more preferable to contain synthetic hydrocarbon oil and synthetic ester oil. The base oil may be used alone or in combination of two or more.

[0013] Mineral oils can be obtained by refining crude oil by an appropriate combination of processes such as vacuum distillation, solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, sulfuric acid washing, clay refining, hydrorefining, etc. Specific examples of mineral oils include paraffinic mineral oils, naphthenic mineral oils, etc.

[0014] Examples of synthetic hydrocarbon oils include FT synthetic oils. In this specification, "FT synthetic oil" refers to synthetic oils consisting of liquid fractions equivalent to naphtha, kerosene, and diesel obtained by applying the Fischer-Tropsch (FT) reaction to a mixed gas (sometimes referred to as synthetic gas) mainly composed of hydrogen and carbon monoxide, and hydrocarbon mixtures obtained by hydrorefining and hydrocracking these, as well as synthetic oils consisting of liquid fractions and FT wax produced by the FT reaction, and then hydrorefining and hydrocracking these. In addition, FT synthetic oils are often called by names according to the raw material, for example, those made from natural gas are called GTL, those made from coal are called CTL, and those made from biomass are called BTL.

[0015] Specific examples of synthetic hydrocarbon oils include poly-α-olefins (PAOs) such as normal paraffin, isoparaffin, polybutene, polyisobutylene, 1-decene oligomers, and 1-decene and ethylene co-oligomers, or hydrogenated products thereof. The carbon number of the α-olefin, which is a monomer component of the PAO, is preferably 6 to 20, more preferably 8 to 16, from the viewpoints of viscosity index and volatility. In addition, the PAO is preferably a dimer to pentamer of α-olefin, from the viewpoints of low volatility and energy saving. The carbon number of the α-olefin, its blending ratio, and polymerization degree of the PAO can be adjusted according to the desired effect, kinetic viscosity, properties, etc.

[0016] In this specification, the term "vegetable oil" refers to oil derived from plants, and includes fats and oils.The vegetable oil that can be used in this embodiment is not particularly limited, but includes, for example, cocoa butter fat, corn oil, peanut oil, sunflower oil, soybean oil, palm oil, olive oil, camellia oil, safflower oil, tallow oil, linseed oil, coconut oil, oak oil, almond oil, apricot kernel oil, castor oil, rapeseed oil, radish oil, China fat, cottonseed oil, sesame oil, palm oil, palm kernel oil, rice bran oil, tung oil, turpentine oil, kapok oil, etc., and preferably at least one selected from the group consisting of corn oil, sunflower oil, safflower oil, castor oil, linseed oil, soybean oil, rapeseed oil, cottonseed oil, olive oil, camellia oil, tung oil, turpentine oil, coconut oil and palm oil. Furthermore, the oils may be a mixture of a plurality of these oils, fats and oils containing diglycerides or monoglycerides, or oils that have been partially oxidized, reduced, or otherwise modified.

[0017] In this specification, "animal oil" refers to oil derived from animals, and includes fats and oils.The animal oil that can be used in this embodiment includes fish oil obtained from fish body such as sardine oil, mackerel oil, herring oil, pacific saury oil, tuna oil, cod liver oil, lard fat, chicken fat, butter fat, beef fat, beef bone fat, deer fat, dolphin fat, horse fat, lard, bone oil, mutton fat, cow foot oil, porpoise oil, shark oil, sperm whale oil, whale oil, etc., and is preferably one or more oils selected from the group consisting of fish oil, beef fat and lard, and may be a mixture of a plurality of these oils, fats and oils containing diglyceride or monoglyceride, or oils that have been partially oxidized, reduced, etc.

[0018] As the synthetic ester oil, polyol esters, fatty acid diesters, and aromatic esters are suitably used, with polyol esters being preferred.

[0019] Examples of polyol esters include esters of aliphatic polyhydric alcohols and linear or branched fatty acids. Examples of aliphatic polyhydric alcohols forming polyol esters include neopentyl glycol, trimethylolpropane, ditrimethylolpropane, trimethylolethane, ditrimethylolethane, pentaerythritol, dipentaerythritol, and tripentaerythritol. Examples of fatty acids forming polyol esters are preferably linear or branched fatty acids having 4 to 22 carbon atoms, and specific examples thereof include butanoic acid, hexanoic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, myristic acid, palmitic acid, oleic acid, stearic acid, isostearic acid, and tridecylic acid. Partial esters of the above-mentioned aliphatic polyhydric alcohols and linear or branched fatty acids can also be used. These partial esters can be obtained by reacting aliphatic polyhydric alcohols and fatty acids while appropriately adjusting the reaction mole number. Specific examples of polyol esters include trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, and pentaerythritol pelargonate.

[0020] Examples of fatty acid diesters include esters of aliphatic alcohols and aliphatic dibasic acids. The alcohol component forming the fatty acid diester is preferably an aliphatic alcohol having 4 to 18 carbon atoms, specifically butyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, and pentadecyl alcohol, and isomers thereof. The fatty acid forming the aliphatic diester is preferably a linear or branched aliphatic dibasic acid having 6 to 10 carbon atoms, specifically adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and those having properties equivalent thereto. Specific examples of fatty acid diesters include dibutyl sebacate, dioctyl sebacate, di-2-ethylhexyl sebacate, dioctyl adipate, diisodecyl adipate, ditridecyl adipate, and dioctyl azelate.

[0021] Examples of aromatic esters include esters of aromatic monobasic acids, aromatic dibasic acids, aromatic tribasic acids, aromatic tetrabasic acids, and other aromatic polybasic acids and alcohols, and preferred are esters of aromatic polybasic acids and aliphatic alcohols having 4 to 18 carbon atoms. Examples of aromatic dibasic acids include phthalic acid and isophthalic acid. Examples of aromatic tribasic acids include trimellitic acid. Examples of aromatic tetrabasic acids include pyromellitic acid. Specific examples of aromatic esters include trioctyl trimellitate, tridecyl trimellitate, and tetraoctyl pyromellitate.

[0022] The carbon number, degree of unsaturation and degree of branching of the carboxylic acid and alcohol that form the polyol ester can be adjusted according to the desired effect, kinetic viscosity, properties and the like.

[0023] As the polyglycol-based synthetic oil, polyalkylene glycol and its alkyl ether are preferably used. As the polyalkylene glycol, for example, polyethylene glycol, polypropylene glycol, polyethylene oxide-propylene oxide (copolymer of ethylene oxide and propylene oxide), poly(methyl-ethylene) glycol, polybutylene glycol, etc. can be mentioned. As the polyalkylene glycol, any of random copolymers, alternating copolymers, block copolymers, and mixtures thereof of polyalkylene glycol obtained by using two or more different alkylene oxides can be used.

[0024] Examples of phenyl ether synthetic oils include monoalkyl triphenyl ethers, alkyl diphenyl ethers, dialkyl diphenyl ethers, pentaphenyl ethers, tetraphenyl ethers, monoalkyl tetraphenyl ethers, and dialkyl tetraphenyl ethers.

[0025] Examples of the silicone-based synthetic oil include dimethylpolysiloxane, diphenylpolysiloxane, and alkyl-modified polysiloxane.

[0026] An example of the fluorine-based synthetic oil is perfluoropolyether.

[0027] The content of the base oil in the grease composition can be appropriately adjusted so that the rotational torque value T and worked penetration P of the grease composition at 25°C satisfy the ranges described below, but from the viewpoint of easily obtaining the effects of the present invention, it is preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, and particularly preferably 82% by mass or more. On the other hand, from the viewpoint of obtaining the effects of the present invention and preventing leakage, scattering, etc. from the place of use, it is preferably 99% by mass or less, more preferably 97% by mass or less, even more preferably 95% by mass or less, and particularly preferably 93% by mass or less.

[0028] The total content of the synthetic hydrocarbon oil, synthetic ester oil, mineral oil, and phenyl ether-based synthetic oil in the base oil (preferably the total content of the synthetic hydrocarbon oil and synthetic ester oil) is preferably 60 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, still more preferably 95 mass% or more, even more preferably 99 mass% or more, and may be 100 mass%.

[0029] The content of the synthetic hydrocarbon oil in the base oil is not particularly limited, but is preferably 10 mass% or more, more preferably 30 mass% or more, even more preferably 50 mass% or more, still more preferably 55 mass% or more, even more preferably 60 mass% or more, still more preferably 65 mass% or more, and particularly preferably 70 mass% or more.

[0030] The mass content ratio of the synthetic ester oil to the synthetic hydrocarbon oil in the base oil is not particularly limited, but is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and particularly preferably 25% by mass or more. The mass content ratio is preferably 90% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, even more preferably 50% by mass or less, even more preferably 45% by mass or less, and particularly preferably 40% by mass or less.

[0031] From the viewpoint of heat resistance of the grease composition, the kinetic viscosity of the base oil at 40°C is set to 25mm 2 / s or more is preferable, 30 mm 2 / s or more is preferable, 32 mm 2 On the other hand, from the viewpoint of suppressing the increase in torque, 140 mm 2 / s or less is preferable, and 100 mm 2 / s or less is preferable, and 85 mm 2 / s or less is more preferable, and 70 mm 2 / s or less is more preferable. 55mm 2 / s or less is particularly preferred.

[0032] (Diurea compounds) The grease composition according to this embodiment contains a diurea compound represented by the following formula (1) as an essential component. R 1 NHCONHR 2 NHCONHR 3 (1) (In the formula, R 1 and R 3 each independently represents a monovalent alicyclic hydrocarbon group or a monovalent aliphatic hydrocarbon group; R 2 represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms.

[0033] R 1 and R 3 are preferably each independently a monovalent alicyclic hydrocarbon group having 4 to 12 carbon atoms or a monovalent aliphatic hydrocarbon group having 6 to 24 carbon atoms; more preferably each independently a monovalent alicyclic hydrocarbon group having 6 to 10 carbon atoms or a monovalent aliphatic hydrocarbon group having 10 to 24 carbon atoms; further preferably each independently a monovalent alicyclic hydrocarbon group having 6 to 8 carbon atoms (e.g., a cyclohexyl group, a methylcyclohexyl group, a dimethylcyclohexyl group, an ethylcyclohexyl group, a cycloheptyl group, a cyclooctyl group) or a monovalent aliphatic hydrocarbon group having 18 to 22 carbon atoms; and particularly preferably each independently a cyclohexyl group or a behenyl group.

[0034] R 2 is preferably a phenylene group, a naphthylene group, a diphenylmethane group, or a tolylene group; more preferably a diphenylmethane group or a tolylene group; and even more preferably a diphenylmethane group.

[0035] The diurea compound represented by formula (1) can be obtained, for example, by reacting a mixed amine consisting of an alicyclic monoamine and an aliphatic monoamine with a diisocyanate compound.

[0036] The alicyclic monoamine is represented by the formula (1): 1 and R 3Examples of such monoamines include monoamines corresponding to the monovalent alicyclic hydrocarbon group represented by the following formula: Preferably, the monovalent alicyclic monoamines have 4 to 12 carbon atoms; more preferably, the monovalent alicyclic monoamines have 6 to 10 carbon atoms; further preferably, the monovalent alicyclic monoamines have 6 to 8 carbon atoms (e.g., cyclohexylamine, methylcyclohexylamine, dimethylcyclohexylamine, ethylcyclohexylamine, cycloheptylamine, cyclooctylamine); and particularly preferably, cyclohexylamine.

[0037] The aliphatic monoamine is represented by the formula (1): 1 and R 3 Examples of monoamines include monoamines corresponding to monovalent aliphatic hydrocarbon groups represented by the following formula: Preferably, they are monovalent aliphatic monoamines having 6 to 24 carbon atoms; more preferably, they are monovalent aliphatic monoamines having 10 to 24 carbon atoms; even more preferably, they are monovalent aliphatic monoamines having 18 to 22 carbon atoms; and behenylamine is particularly preferred.

[0038] R 1 and R 3 Of the total amount of monovalent alicyclic hydrocarbon groups, there are no particular limitations and the proportion can be appropriately adjusted so that the rotational torque value T and worked penetration P of the grease composition at 25°C satisfy the ranges described below. From the viewpoint of easily achieving the effects of the present invention, however, the proportion is preferably 45 to 65 mol%, more preferably 47 to 63 mol%, and even more preferably 50 to 60 mol%.

[0039] The molar ratio of the alicyclic monoamine to the aliphatic monoamine in the amine mixture (alicyclic monoamine:aliphatic monoamine) is not particularly limited, but from the viewpoint of easily achieving the effects of the present invention, it is preferably 45:55 to 65:35, more preferably 47:53 to 63:37, and even more preferably 50:50 to 60:40.

[0040] The diisocyanate compound is, for example, 2Examples of the diisocyanate compounds include those corresponding to a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms, and are preferably diphenylmethane-4,4'-diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and naphthylene-1,5-diisocyanate. Among these, diphenylmethane-4,4'-diisocyanate is preferred from the viewpoint of heat resistance.

[0041] The reaction between the mixed amine and the diisocyanate compound can be carried out by various methods and under various conditions, but it is preferable to carry out the reaction in a base oil, since a diurea compound having a high uniform dispersion of the thickener can be obtained. The reaction may be carried out by adding a base oil having a diisocyanate compound dissolved therein to a base oil having a mixed amine dissolved therein, or by adding a base oil having a mixed amine dissolved therein to a base oil having a diisocyanate compound dissolved therein.

[0042] The temperature and time in the reaction are not particularly limited and may be the same as those of ordinary reactions of this type. The reaction temperature is preferably 80 to 100°C in terms of the solubility and volatility of the mixed amine and diisocyanate. The reaction time is preferably less than 0.5 hours in terms of completing the reaction of the mixed amine and diisocyanate and in terms of efficiency by shortening the production time, and the reaction may be performed while mixing and raising the temperature without setting a reaction time. In addition, the reaction between the amino group of the mixed amine and the isocyanate group of the diisocyanate compound proceeds quantitatively, and the ratio thereof is preferably 2 moles of the mixed amine to 1 mole of the diisocyanate compound.

[0043] The diurea compound obtained by the reaction is a mixture of diurea compounds (a) in which both isocyanate groups of a diisocyanate compound react with an alicyclic amine in the mixed amine, diurea compound (b) in which both isocyanate groups of a diisocyanate compound react with an aliphatic amine in the mixed amine, and diurea compound (c) in which one of the isocyanate groups of a diisocyanate compound reacts with an alicyclic amine and the other with an aliphatic amine. The diurea compound used in this embodiment also includes a diurea compound obtained by synthesizing each of the diurea compounds (a) to (c) and mixing them.

[0044] The content of the diurea compound represented by formula (1) in the grease composition is not particularly limited and can be appropriately adjusted so that the rotational torque value T and worked penetration P of the grease composition at 25°C satisfy the ranges described below. From the viewpoint of easily achieving the effects of the present invention, however, the content is preferably 8.0 to 14.0 mass%, more preferably 8.5 to 13.0 mass%, and even more preferably 9.0 to 12.0 mass%.

[0045] (optional ingredient) The grease composition of the present embodiment may further contain optional components within the range that does not impair the effects of the present invention. The optional components include thickeners other than the diurea compound, dispersants, antioxidants, antiwear agents, rust inhibitors, extreme pressure additives, dyes, color stabilizers, thickeners, structure stabilizers, metal deactivators, etc.

[0046] Examples of thickeners other than the diurea compounds include metal soaps such as lithium soap, lithium complex soap, calcium soap, sodium soap, and aluminum soap; sodium terephthalamate; organo-bentonite; and silica gel.

[0047] Examples of lithium soaps include those formed by reacting a fatty acid having 10 to 28 carbon atoms or a hydroxy acid having 10 to 28 carbon atoms with lithium hydroxide. Among these, lithium laurate, lithium stearate, and lithium 12-hydroxystearate are preferred.

[0048] Examples of lithium complex soaps include those formed by reacting an aliphatic monocarboxylic acid having 12 to 24 carbon atoms and at least one hydroxy group, an aliphatic dicarboxylic acid having 2 to 12 carbon atoms, and lithium hydroxide. Among these, those formed by reacting a mixture of 12-hydroxystearic acid and azelaic acid with lithium hydroxide are preferred.

[0049] When a thickener other than the diurea compound is contained, the content in the grease composition is preferably less than 5.0 parts by mass, more preferably less than 1.0 part by mass, and even more preferably less than 0.1 part by mass, and the grease composition may not contain any thickener other than the diurea compound.

[0050] Examples of dispersants include metal sulfonates such as magnesium sulfonate, calcium sulfonate, calcium sulfonate complex, zinc sulfonate, barium sulfonate, etc.; metal salicylates such as calcium salicylate, etc.; metal phenates such as calcium phenate, etc. These dispersants may be used alone or in combination of two or more.

[0051] When a dispersant is contained, the content in the grease composition is preferably at least 0.1 part by mass, more preferably from 0.5 to 10 parts by mass, and even more preferably from 1.0 to 5.0 parts by mass.

[0052] The antioxidant is not particularly limited as long as it is one that is generally added to a grease composition, but phenol-based antioxidants and amine-based antioxidants are preferably used. The antioxidants may be used alone or in combination of two or more kinds.

[0053] Examples of phenol-based antioxidants include 2,6-di-t-butyl-4-methylphenol, 4,4-methylenebis(2,6-di-t-butylphenol), octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4 -hydroxybenzyl)benzene, triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,2-thio-diethylene bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylene bis(3,5-di-t-butyl-4-hydroxy-hydrocinnamide), octyl-3,5-di-tert-butyl-4-hydroxy-hydrocinnamic acid, and the like.

[0054] As the amine-based antioxidant, an aromatic amine compound is desirable, and examples thereof include diphenylamine, alkylated diphenylamine, phenothiazine, alkylated phenothiazine, phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine, p,p'-diaminodiphenylmethane, aldol-α-naphthylamine, triphenylamine, hindered amine, and the like. From the viewpoint of seizure resistance, alkylated diphenylamine is preferable.

[0055] When an antioxidant is contained, the content in the grease composition is preferably at least 0.1 part by mass, more preferably from 0.5 to 10 parts by mass, and even more preferably from 1.0 to 5.0 parts by mass.

[0056] Examples of the anti-wear agent include phosphate esters such as tricresyl phosphate (TCP) and lauryl acid phosphate; phosphites such as tributyl phosphite and trioleyl phosphite; acidic phosphate amine salts such as dibutyl octylamine phosphate and dilauryl octylamine phosphate; dithiophosphates such as zinc dialkyl dithiophosphate (ZnDTP) and molybdenum dialkyl dithiophosphate (MoDTP); dithiocarbamates such as zinc dithiocarbamate (ZnDTC), molybdenum dithiocarbamate (MoDTC), bismuth dithiocarbamate (BiDTC), and antimony dithiocarbamate (SbDTC); and phosphorothioates such as triphenyl phosphorothioate and alkyl phosphorothioate. These anti-wear agents may be used alone or in combination of two or more.

[0057] When an anti-wear agent is contained, the content in the grease composition is preferably at least 0.1 part by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 1.0 to 5.0 parts by mass.

[0058] Examples of the rust inhibitor include sulfonates, carboxylic acids, carboxylates, ester-based rust inhibitors, amine-based rust inhibitors, etc. The rust inhibitors may be used alone or in combination of two or more kinds.

[0059] The sulfonate is a metal sulfonate such as an alkali metal sulfonate or an alkaline earth metal sulfonate, an amine sulfonate, etc. The sulfonate can be prepared by reacting an alkali metal, an alkaline earth metal or an amine with a sulfonic acid.

[0060] The sulfonic acid constituting the sulfonate is preferably petroleum sulfonic acid and dinonylnaphthalene sulfonic acid. The alkali metal constituting the sulfonate is exemplified by sodium, potassium, etc. The alkaline earth metal is exemplified by magnesium, calcium, barium, etc. Among these, the metal salt is preferably sodium salt, potassium salt, calcium salt, or barium salt, and more preferably calcium salt. In addition, when the sulfonate is an amine salt, the amine is exemplified by monoamine, polyamine, alkanolamine, etc.

[0061] Among the sulfonates, amine sulfonate, calcium sulfonate, or barium sulfonate is preferable. The sulfonate may be used alone or in combination of two or more of the above-mentioned examples.

[0062] Examples of the carboxylic acid include monocarboxylic acids such as stearic acid and oleic acid, alkylsuccinic acids and derivatives thereof, alkenylsuccinic acids and derivatives thereof, naphthenic acid, abietic acid, lanolin fatty acids, etc. Examples of the carboxylate include metal salts (calcium, barium, magnesium, aluminum, zinc, lead, etc.) and amine salts of the above-mentioned carboxylic acids.

[0063] Examples of the ester-based rust inhibitor include fatty acid esters of polyhydric alcohols such as sorbitan fatty acid esters, glycerin fatty acid esters, and pentaerythritol fatty acid esters, and dodecenyl succinic acid half esters.

[0064] Examples of the amine-based rust inhibitor include amine derivatives such as alkoxyphenylamines, and partial amides of dibasic carboxylic acids.

[0065] When a rust inhibitor is contained, the content in the grease composition is preferably at least 0.1 part by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 1.0 to 5.0 parts by mass.

[0066] Examples of the extreme pressure additives include sulfurized oils and fats; sulfides such as dibenzyl disulfide and alkyl polysulfides; and chlorinated paraffins.

[0067] When an extreme pressure additive is contained, the content in the grease composition is preferably at least 0.1 part by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 1.0 to 5.0 parts by mass.

[0068] From the viewpoint of the effects of the present invention, the rotational torque value T of the grease composition according to this embodiment at 25°C is preferably 6.5 mN·m or less, more preferably 6.0 mN·m or less, even more preferably 5.5 mN·m or less, even more preferably 5.0 mN·m or less, even more preferably 4.5 mN·m or less, and particularly preferably 4.0 mN·m or less. On the other hand, the lower limit of T is not particularly limited, but is usually 1.0 mN·m or more. In this specification, the rotational torque value is measured when 0.7 g of the grease composition is packed in the bearing (6202) and the rotation speed is 3600 min -1 It is determined by rotating the bearing for 10 minutes with an axial load of 9.8 N and calculating the average value of the rotational torque generated in the bearing for the last 5 minutes of the test.

[0069] The worked penetration P of the grease composition according to this embodiment is preferably 200 or more, more preferably 220 or more, even more preferably 230 or more, and particularly preferably 240 or more, from the viewpoint of sealing in the bearing. On the other hand, from the viewpoint of preventing leakage from the bearing and reducing stirring resistance, it is preferably 340 or less, more preferably 320 or less, and even more preferably 295 or less. In this specification, the worked penetration is measured in accordance with JIS K 2220-7.

[0070] The grease composition according to the present embodiment is characterized in that the T / P is less than 0.019. The T / P is preferably less than 0.018, more preferably less than 0.017, even more preferably less than 0.016, and particularly preferably less than 0.015. On the other hand, the lower limit of the T / P is not particularly limited, but is usually 0.003 or more.

[0071] In order to set the rotational torque value T, worked penetration P, and T / P of the grease composition according to this embodiment within the above-mentioned specified ranges, the content of the diurea compound in the grease composition, the combination and ratio of the alicyclic amines and aliphatic amines in the amine mixture used to produce the diurea compound, the type of base oil, the mixing ratio, the kinematic viscosity, etc. can be appropriately changed.

[0072] The use of the grease composition according to the present embodiment is not particularly limited, but it can be filled, for example, in bearings such as rolling bearings, thrust bearings, hydrodynamic bearings, resin bearings, and linear motion devices, and is preferably filled in rolling bearings. Examples of products equipped with such bearings (preferably rolling bearings) include general-purpose motors.

[0073] In addition, the grease composition according to this embodiment can be widely applied to power transmission devices such as reducers, speed increasers, gears, chains, motors, etc., driving system parts, control system parts such as ABS, steering system parts, drive system parts such as transmissions, automobile reinforcement parts such as power window motors, power seat motors, sunroof motors, hinge parts for electronic information devices, mobile phones, etc., various parts and mechanical parts that move relative to one another in the food and pharmaceutical industries, steel, construction, glass industry, cement industry, chemical, rubber and resin industries such as film tenters, environment and power equipment, paper and printing industries, wood industry, and textile and apparel industries. EXAMPLES

[0074] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these.

[0075] In this example, the following raw materials were used: MDI: Millionate MT-F (diphenylmethane-4,4'-diisocyanate, molecular weight: 250.25) manufactured by Nippon Polyurethane Industry Co., Ltd. Amine Alicyclic amine: CYCROHEXYLAMINE (cyclohexylamine, molecular weight: 99.17) manufactured by BorsodChem Aliphatic amine: Amine VB-S (behenylamine, molecular weight: 325.62) manufactured by NOF Corporation Mixed base oil: Poly-α-olefin (Kinematic viscosity (40℃): 30mm 2 / s), Polyol ester A (Kinematic viscosity (40℃): 112mm 2 / s), and Polyol Ester B (Kinematic Viscosity (40℃): 25mm 2 / s) mixed in a ratio of 75:10:15 (mixed base oil kinetic viscosity (40℃): 35mm 2 / s) Dispersant: NA-SUL CA-770FG (calcium sulfonate) manufactured by King Industries Antioxidant 1: IRGANOX L57 (alkylated diphenylamine) manufactured by BASF Japan Ltd. Antioxidant 2: IRGANOX L101 manufactured by BASF Japan Ltd. (phenolic antioxidant: pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]) Anti-wear agent: ADEKA KICLUB Z-112 (ZnDTP) manufactured by ADEKA Corporation Rust inhibitor 1: MORESCO Amber SB-50N (barium sulfonate) manufactured by MORESCO Corporation Rust inhibitor 2: Rheomix TDO (fatty acid amine salt: N-tallow alkyl-1,3-diaminopropane oleate) manufactured by Lion Specialty Chemicals Co., Ltd. Rust inhibitor 3: NOF Corporation's Nonion OP-80R (sorbitan monooleate)

[0076] Examples and Comparative Examples Each grease composition for testing was prepared according to the formulation shown in Table 2. First, calcium sulfonate and each amine were added to the base oil and maintained at 80 - 90 °C. Further, a diisocyanate compound dissolved in the base oil was added, and the mixture was heated to 160 °C with stirring, and an extreme pressure agent was added. Then, it was cooled with stirring and homogenized by a homogenizer treatment (pressure about 300 bar) to obtain a base grease. Thereafter, other additives were added to the base grease, homogenized by a three-roll mill, and then stirred and defoamed to prepare each grease composition for testing. The following evaluations were performed on the obtained grease compositions for testing. The results are shown in Table 2.

[0077] <Rotating Torque Test> The bearing rotating torque of each grease composition for testing was measured according to the test conditions in Table 1 below using a rotating torque tester. The rotation was carried out for 10 minutes, and the average value of the rotating torque generated in the bearing during the last 5 minutes before the end of the test was calculated, and the rotating torque value T (mN·m) was displayed.

[0078]

Table 1

[0079] <Measurement of Penetration> In accordance with JIS K 2220-7, in an environment of 25 °C, a cone attached to a penetrometer was dropped onto each grease composition for testing, and the depth (mm) of penetration over 5 seconds was measured. The measured value multiplied by 10 was defined as the penetration P.

[0080] <SRV Test> In accordance with ASTM D5706, the seizure load (N) of each grease composition for testing was measured under the following test conditions and evaluated according to the following criteria. The threshold value was set at 1,500 N. (Test Conditions) Ball diameter: 10 mm Frequency: 50 Hz Stroke: 1.0 mm Test temperature: 25 °C Test load: Step Load (100 N / 2 min) Test time: 2 minutes at each load (Evaluation Criteria) A: Exceeded the threshold B: Burned in at threshold C: The threshold was not reached.

[0081] [Table 2]

[0082] From the results in Table 2, it can be seen that the grease composition containing the diurea compound specified in the present application has the unexpected property of low rotational torque relative to worked penetration. In addition, the results of the SRV test reveal that the grease composition has a certain level of lubricity, and an improvement in lubrication life can be expected.

Claims

1. A base oil and a compound represented by the following formula (1): R 1 NHGNHR 2 NHGNHR 3 ・・・(1) (In the formula, R 1 and R 3 each independently represents a monovalent alicyclic hydrocarbon group or a monovalent aliphatic hydrocarbon group; R 2 represents a divalent aromatic hydrocarbon group having 6 to 15 carbon atoms. A grease composition containing a diurea compound represented by the formula: A grease composition, in which T / P is less than 0.019, where P is the worked penetration of the grease composition and T (mN·m) is the rotational torque value of the grease composition at 25° C.

2. 2. The grease composition according to claim 1, wherein the monovalent alicyclic hydrocarbon group has 4 to 12 carbon atoms, and the monovalent aliphatic hydrocarbon group has 6 to 24 carbon atoms.

3. 2. The grease composition according to claim 1, wherein the monovalent alicyclic hydrocarbon group has 6 to 10 carbon atoms, and the monovalent aliphatic hydrocarbon group has 10 to 24 carbon atoms.

4. 2. The grease composition according to claim 1, wherein the monovalent alicyclic hydrocarbon group has 6 to 8 carbon atoms, and the monovalent aliphatic hydrocarbon group has 18 to 22 carbon atoms.

5. R 1 and R 3 2. The grease composition according to claim 1, wherein the proportion of monovalent alicyclic hydrocarbon groups is 45 to 65 mol % of the total amount of said grease composition.

6. The grease composition according to claim 1, wherein the grease composition has a worked penetration P of 200 to 330.

7. The grease composition according to any one of claims 1 to 6, wherein the monovalent aliphatic hydrocarbon group is a behenyl group.

8. The grease composition according to any one of claims 1 to 6, wherein the content of the diurea compound represented by formula (1) in the grease composition is 8.0 to 14.0 mass%.

9. The base oil has a kinetic viscosity of 25 to 140 mm at 40°C. 2 The grease composition according to any one of claims 1 to 6, wherein

10. The grease composition according to any one of claims 1 to 6, wherein the base oil comprises a synthetic hydrocarbon oil and a synthetic ester oil.

11. A bearing packed with the grease composition according to any one of claims 1 to 6.

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