Lubricant

Abstract

This lubricant contains 40 mass% or more of a liquid polyolefin wax (A) and 20 mass% or more of an amide compound (B) with respect to 100 mass% of the lubricant.

Description

lubricant

[0001] The present invention relates to lubricants.

[0002] Patent Document 1 describes a grease composition for ball joints that contains a base oil, a thickener, and an additive, wherein the base oil contains an ethylene-α-olefin copolymer, and the kinematic viscosity of the base oil at 40°C is 2,000 to 6,000 mm ２ and the additive comprises a wax having polarity.

[0003] Patent Document 2 discloses a lubricant composition for ball joints that contains a base oil containing a synthetic hydrocarbon oil, a thickener, and a fatty acid salt of a compound represented by formula (1): １ -NH-R ２ -NH ２ (1) (wherein, R １ is a hydrocarbon group having 1 to 24 carbon atoms, R ２ represents an alkylene group having 2 to 4 carbon atoms.

[0004] Japanese Patent Application Publication No. 2017-149905 International Publication No. 2003 / 006590

[0005] Torque is an important factor in determining the ride comfort and fuel economy of an automobile, and therefore lubricants for automotive ball joints are required to have low torque at room temperature and at low temperatures (e.g., −40° C.).

[0006] However, in the conventional technology described above, if the lubricant is made thicker in consideration of the friction characteristics at room temperature, the lubricant becomes even thicker at low temperatures, which results in a problem of deterioration of the friction characteristics at low temperatures.

[0007] An object of one aspect of the present invention is to provide a lubricant that has good friction characteristics at room temperature and can ensure sufficient friction characteristics at low temperatures.

[0008] As a result of intensive research to solve the above-mentioned problems, the present inventors have found for the first time that a lubricant containing specific amounts of a liquid polyolefin wax and an amide compound has good friction properties at room temperature and at low temperatures, and have completed the present invention. That is, in order to solve the above-mentioned problems, a lubricant according to one aspect of the present invention contains 40 mass% or more of a liquid polyolefin wax (A) and 20 mass% or more of an amide compound (B) relative to 100 mass% of the lubricant.

[0009] According to one aspect of the present invention, it is possible to realize a lubricant that can maintain good friction characteristics at room temperature and also ensure sufficient friction characteristics at low temperatures.

[0010] 1 is a schematic diagram showing the configuration of a ball joint testing machine used to evaluate joint torque in Examples 2 and 3. It is a schematic diagram showing the configuration of a nanourea-based grease production device used to produce nanourea-based grease in Examples 3 and 4.

[0011] Hereinafter, one embodiment of the present invention will be described in detail. In this specification, unless otherwise specified, the expression "A to B" representing a range of numerical values ​​means "A or more and B or less."

[0012] [1. Lubricant] A lubricant according to one embodiment of the present invention contains 40% by mass or more of a liquid polyolefin wax (A) and 20% by mass or more of an amide compound (B) relative to 100% by mass of the lubricant.

[0013] The lubricant according to one embodiment of the present invention contains the liquid polyolefin wax (A) and the amide compound (B) in the above-mentioned specific amounts, thereby achieving a lubricant with good friction characteristics at room temperature and at low temperatures. Therefore, the lubricant according to one embodiment of the present invention contributes to improving fuel efficiency by reducing the load on automobile batteries and improving environmental resistance. Such effects also contribute to achieving, for example, Goal 9 of the United Nations' Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization, and promote innovation and resilience."

[0014] Unless otherwise specified, in this specification, "normal temperature" means 15°C to 35°C, and "low temperature" means 0°C to -50°C.

[0015] In this specification, the friction characteristics at room temperature are evaluated as follows: Specifically, an evaluation standard of "A," which is set based on the starting torque and steady-state torque at room temperature measured by a joint torque evaluation test shown in the examples described later, is evaluated as good friction characteristics at room temperature.

[0016] In this specification, the friction characteristics at low temperatures are evaluated as follows: Specifically, a starting torque at low temperatures of 900 mN m or less and a steady torque at low temperatures of 900 mN m or less, measured in accordance with JIS K2220:2013, are evaluated as having good friction characteristics at low temperatures.

[0017] Here, the starting torque is the torque required to output power from a stationary state, and the smaller the torque, the better the friction characteristics, which is preferable. The steady-state torque is the torque required to continuously output power, and the smaller the torque, the better the friction characteristics, which is preferable. Therefore, in this specification, a starting torque of 600 mN m or less at low temperatures and a steady-state torque of 450 mN m or less at low temperatures are evaluated as having even better friction characteristics at low temperatures.

[0018] <Liquid Polyolefin Wax (A)> The liquid polyolefin wax (A) has the effect of reducing the torque of the lubricant according to one embodiment of the present invention at room temperature and low temperature.

[0019] The liquid polyolefin wax (A) contained in the lubricant according to one embodiment of the present invention is not particularly limited as long as it is a liquid wax containing a polyolefin. Here, the term "liquid wax" refers to a wax that is liquid at 25°C.

[0020] Specific examples of such liquid polyolefin wax (A) include liquid polyethylene wax, liquid polypropylene wax, etc. Among these, liquid polyethylene wax is preferred.

[0021] In addition, from the viewpoint of preventing an increase in torque, the liquid polyolefin wax (A) has a kinematic viscosity of 100 mm at 40°C. ２ / s or more, and 200 mm ２ / s or more is more preferable, and 300 mm２ In this specification, the kinematic viscosity at 40°C means a value measured in accordance with JIS K2283:2000. There is no particular upper limit, but it is preferable that the kinematic viscosity is 400 mm ２ / s or less.

[0022] (Content of Liquid Polyolefin Wax (A)) The lubricant according to one embodiment of the present invention contains 40% by mass or more of the liquid polyolefin wax (A) relative to 100% by mass of the lubricant, thereby achieving the effect of reducing torque at room temperature and low temperatures.

[0023] From the viewpoint of reducing the room temperature torque, the content of the liquid polyolefin wax (A) in the lubricant according to one embodiment of the present invention is 40% by mass or more relative to 100% by mass of the lubricant.

[0024] Furthermore, there is no particular upper limit to the content of the liquid polyolefin wax (A), but the content of the liquid polyolefin wax (A) in the lubricant according to one embodiment of the present invention is more preferably 80% by mass or less, and even more preferably 70% by mass or less, relative to 100% by mass of the lubricant.

[0025] <Amide Compound (B)> The amide compound (B) has the effect of reducing the torque of the lubricant according to one embodiment of the present invention at room temperature and low temperature. Because the amide compound (B) is easily adsorbed to metal surfaces, the molecules of the amide compound (B) adhering to the metal surface provide a friction-reducing effect in boundary lubrication. As a result, it is presumed that low torque is achieved in resin-metal lubrication.

[0026] The amide compound (B) contained in the lubricant according to one embodiment of the present invention may be any compound having at least one amide bond in the molecule. The amide compound (B) is preferably an acid amide obtained by reacting a carboxylic acid with an amine, and more preferably a fatty acid amide.

[0027] Examples of carboxylic acids include linear or branched saturated or unsaturated monocarboxylic acids, and specific examples thereof include saturated fatty acids such as heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid (including stearic acid), nonadecanoic acid, icosanoic acid, henicosanoic acid, docosanoic acid, tricosanoic acid, and tetracosanoic acid; and unsaturated fatty acids such as heptenoic acid, octenoic acid, nonenoic acid, decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, pentadecenoic acid, hexadecenoic acid, heptadecenoic acid, octadecenoic acid (including oleic acid), nonadecenoic acid, icosenoic acid, henicosenoic acid, docosenoic acid, tricosenoic acid, and tetracosenoic acid. These saturated and unsaturated fatty acids may be either straight-chain or branched, and the double bond in the unsaturated fatty acid may be at any position.

[0028] The carboxylic acids preferably have 7 to 30 carbon atoms, more preferably 8 to 24 carbon atoms, and even more preferably 10 to 22 carbon atoms.

[0029] Examples of amines include alkylamines, alkanolamines, and polyalkylenepolyamines.

[0030] Examples of alkylamines include primary aliphatic alkylamines such as monomethylamine, monoethylamine, monopropylamine, monobutylamine, monopentylamine, monohexylamine, and monoheptylamine; and secondary aliphatic alkylamines such as dimethylamine, methylethylamine, diethylamine, methylpropylamine, ethylpropylamine, dipropylamine, methylbutylamine, ethylbutylamine, propylbutylamine, dibutylamine, dipentylamine, dihexylamine, and diheptylamine. The alkyl group in the alkylamine may be either linear or branched.

[0031] Examples of alkanolamines include monomethanolamine, monoethanolamine, monopropanolamine, monobutanolamine, monopentanolamine, monohexanolamine, dimethanolamine, methanolethanolamine, diethanolamine, methanolpropanolamine, ethanolpropanolamine, dipropanolamine, methanolbutanolamine, ethanolbutanolamine, propanolbutanolamine, dibutanolamine, dipentanolamine, dihexanolamine, etc. The alkanol group in the alkanolamine may be either linear or branched.

[0032] Examples of polyalkylene polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, tetrapropylenepentamine, and hexabutyleneheptamine.

[0033] The amide compound (B) is preferably at least one amide compound selected from the group consisting of saturated fatty acid amides (B1) and unsaturated fatty acid amides (B2). The saturated fatty acid amides (B1) and unsaturated fatty acid amides (B2) may be monoamides having one bond in the molecule, or bisamides having two amide groups in the molecule.

[0034] Specific examples of the saturated fatty acid amide (B1) include saturated fatty acid monoamides such as caprylic acid amide, capric acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, hydroxystearic acid amide, 12-hydroxystearic acid amide, behenic acid amide, and montanic acid amide; methylene biscaprylic acid amide, methylene biscapric acid amide, methylene bislauric acid amide, methylene bismyristic acid amide, methylene bispalmitic acid amide, methylene bisstearic acid amide, methylene bisisostearic acid amide, methylene bisbehenic acid amide, ethylene biscaprylic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bismyristic acid amide, and ethylene Examples of saturated fatty acid bisamides include, but are not limited to, bispalmitic acid amide, ethylene bisstearic acid amide, ethylene bisisostearic acid amide, ethylene bisbehenic acid amide, butylene bisstearic acid amide, butylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, m-xylylene bisstearic acid amide, m-xylylene bis-12-hydroxystearic acid amide, p-xylylene bisstearic acid amide, p-phenylene bisstearic acid amide, methylene bishydroxystearic acid amide, ethylene bishydroxystearic acid amide, butylene bishydroxystearic acid amide, and hexamethylene bishydroxystearic acid amide.

[0035] Specific examples of the unsaturated fatty acid amide (B2) include, but are not limited to, unsaturated fatty acid monoamides such as undecylenic acid amide, oleic acid amide, erucic acid amide, and linoleic acid amide; and unsaturated fatty acid bisamides such as methylene bisoleic acid amide, methylene biserucic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, butylene bisoleic acid amide, butylene biserucic acid amide, hexamethylene bisoleic acid amide, and hexamethylene biserucic acid amide.

[0036] The amide compound (B) may be used alone or in combination of two or more kinds.

[0037] From the viewpoint of suppressing stick-slip at low temperatures, the amide compound (B) preferably contains a saturated fatty acid amide (B1) and an unsaturated fatty acid amide (B2) in combination, and more preferably contains ethylene bisstearic acid amide (B1) and ethylene bisoleic acid amide (B2) in combination.

[0038] Here, in this specification, stick-slip prevention is evaluated based on the difference between the starting torque and steady-state torque at low temperatures. The smaller the difference between the starting torque and steady-state torque at low temperatures, the less likely stick-slip occurs at low temperatures. For this reason, in this specification, a difference between the starting torque and steady-state torque at low temperatures of 450 mN m or less is evaluated as good stick-slip prevention, a difference of 350 mN m or less is evaluated as better stick-slip prevention, and a difference of 250 mN m or less is evaluated as even better stick-slip prevention.

[0039] When the amide compound (B) contains a combination of the saturated fatty acid amide (B1) and the unsaturated fatty acid amide (B2), the effect of improving stick-slip suppression at low temperatures can be obtained.

[0040] Furthermore, from the viewpoint of ease of preparation into a grease and the spinnability of the obtained lubricant, the amide compound (B) contained in the lubricant according to one aspect of the present invention preferably has a melting point of 70°C or higher, more preferably 90°C or higher, and even more preferably 110°C or higher.

[0041] Furthermore, from the viewpoint of making the grease semi-solid, the amide compound (B) contained in the lubricant according to one aspect of the present invention preferably has a melting point of 180° C. or less, more preferably 170° C. or less, and even more preferably 150° C. or less. In this specification, the melting point of the amide compound (B) refers to a value measured by the method of JIS K 0064:1992.

[0042] (Content of Amide Compound (B)) The lubricant according to one embodiment of the present invention contains 20% by mass or more of the amide compound (B) relative to 100% by mass of the lubricant. This allows for reduced torque at room temperature and low temperatures.

[0043] From the viewpoint of making the lubricant semi-solid, the content of the amide compound (B) in the lubricant according to one embodiment of the present invention is 20% by mass or more relative to 100% by mass of the lubricant.

[0044] Furthermore, although there is no particular upper limit to the content of the amide compound (B), from the viewpoint of maintaining a grease-like (semi-solid) state, the content of the amide compound (B) in the lubricant according to one embodiment of the present invention is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less, relative to 100% by mass of the lubricant.

[0045] When the lubricant according to one embodiment of the present invention contains a plurality of types of amide compounds (B), the total content of the amide compounds (B) may be adjusted to fall within the above range.

[0046] When the amide compound (B) contains ethylene bisstearamide (B1) and ethylene bisoleamide (B2), the content ratio of the ethylene bisstearamide (B1) to the ethylene bisoleamide (B2) [(B1) / (B2)] is, for example, preferably 0.7 or more, more preferably 0.8 or more, and even more preferably 0.9 or more, by mass, thereby preventing the lubricant from becoming too soft. Furthermore, although not particularly limited, the content ratio of the ethylene bisstearamide (B1) to the ethylene bisoleamide (B2) [(B1) / (B2)] can be 1.6 or less, 1.5 or less, or 1.4 or less.

[0047] <Urea Grease Composition (C)> A lubricant according to one aspect of the present invention is a urea grease composition comprising a base oil and a urea-based thickener, and the particles comprising the urea-based thickener in the urea grease composition further contain a urea grease composition (C) that satisfies the following requirement (I), and it is preferable that the content of the urea grease composition (C) in the lubricant is 5 mass % or more and less than 20 mass %: Requirement (I): The arithmetic mean particle diameter on an area basis when the particles are measured by a laser diffraction / scattering method is 2.0 μm or less.

[0048] In this specification, the urea grease composition (C) containing particles containing a urea-based thickener that satisfies the above requirement (I) may be referred to as a "nanourea grease composition."

[0049] The lubricant according to one embodiment of the present invention further contains the urea grease composition (C) in the specific content described above, thereby improving the friction characteristics at low temperatures.

[0050] The urea grease composition (C) contained in the lubricant according to one embodiment of the present invention can be obtained by a known method for producing a nanourea grease composition. For example, the urea grease composition (C) preferably contains a base grease containing particles containing a urea-based thickener that satisfies the requirement (I). In this specification, the term "base grease" refers to a mixture of a base oil and a thickener that does not contain any additives. A base grease containing particles containing a urea-based thickener that satisfies the requirement (I) may be referred to as a "nanourea-based grease."

[0051] The method for producing the nanourea-based grease is not particularly limited. For example, the raw material of the base grease is subjected to a shear rate of 10 ２ s －１ or more, preferably 10 ３ s －１ More preferably, 10 ４ s －１ By applying the high shear force described above, a nanourea-based grease can be obtained as a mixture of thickener particles dispersed in a base oil. Such a method for producing a nanourea-based grease is known and is disclosed, for example, in Japanese Patent Application Laid-Open No. 2016-141803.

[0052] The urea grease composition (C) may be a nanourea-based grease containing no additives, or may be a nanourea grease composition containing additives.

[0053] The types of base oil and urea-based thickener contained in the urea grease composition (C) are not particularly limited. The base oil contained in the urea grease composition (C) can be any of the base oils classified into Groups I, II, III, IV, and V according to the base oil categories of the American Petroleum Institute (API), and these may be used alone or in combination of two or more. Examples of such base oils include mineral oil-based base oils and synthetic base oils. Water or an organic acid may be added as needed.

[0054] The mineral base oil may be one that has been refined by an appropriate combination of vacuum distillation, solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, sulfuric acid washing, clay refining, hydrorefining, and the like.

[0055] Examples of synthetic base oils include polyalphaolefin (PAO) base oils, other hydrocarbon base oils, ester base oils, alkyldiphenyl ether base oils, polyalkylene glycol base oils (PAG), alkylbenzene base oils, and GTL (Gas To Liquids) base oils obtained by hydroisomerization dewaxing wax produced from natural gas by the Fischer-Tropsch process, etc. These may be used alone or in combination of two or more.

[0056] The kinematic viscosity of the base oil at 40°C is 10 mm ２ / s or more, 600mm ２ / s or less, and ２ / s or more, 300mm ２ / s or less is more preferable, and 30 mm ２ / s or more, 100mm ２ It is more preferable that the ratio is 1 / s or less.

[0057] The urea-based thickener contained in the urea grease composition (C) is not particularly limited, and examples of thickener precursors include monoamines and isocyanates (diisocyanates). The monoamine may be either a single amine compound or a mixture containing multiple amine compounds.

[0058] Examples of monoamines include aromatic monoamines such as aniline, p-toluidine, and naphthylamine; and aliphatic monoamines such as hexylamine, cyclohexylamine, octylamine, dodecylamine, hexadecylamine, and eicosylamine.

[0059] Examples of isocyanates include diphenylmethane-4,4'-diisocyanate (MDI), tolylene diisocyanate, and naphthylene-1,5-diisocyanate.

[0060] Polyurea compounds can be obtained, for example, by reacting diisocyanates with monoamines or diamines. Examples of diisocyanates and monoamines include those used to produce diurea compounds. Examples of diamines include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylenediamine, and diaminodiphenylmethane.

[0061] The above-mentioned amines may be used alone or in combination of two or more thereof, and the above-mentioned isocyanates may be used alone or in combination of two or more thereof.

[0062] (Particle diameter of particles containing a urea-based thickener) The particles containing a urea-based thickener in the urea grease composition (C) satisfy the following requirement (I): Requirement (I): The arithmetic mean particle diameter on an area basis when the particles are measured by a laser diffraction / scattering method is 2.0 μm or less.

[0063] Here, the "particles containing a thickener" to be measured by the laser diffraction / scattering method refer to particles formed by aggregation of the urea thickener contained in the urea grease composition (C). Therefore, the requirement (I) can also be said to be a parameter indicating the state of aggregation of the urea thickener in the urea grease composition (C). When the urea grease composition (C) contains an additive other than a urea thickener, the particle size specified by the requirement (I) can be obtained by measuring the urea grease composition (C) prepared under the same conditions but without the additive by the laser diffraction / scattering method. However, when the additive is liquid at room temperature or dissolves in the base oil, the urea grease composition (C) containing the additive may also be used as the measurement target.

[0064] The urea grease composition (C) contains a urea-based thickener that satisfies the requirement (I), and therefore the urea grease composition (C) itself has high shear stability and excellent low-temperature properties.

[0065] From the viewpoint of shear stability and low-temperature properties, the particle size specified by the requirement (I) is preferably 1.5 μm or less, more preferably 1.0 μm or less, even more preferably 0.9 μm or less, still more preferably 0.8 μm or less, even more preferably 0.7 μm or less, still more preferably 0.6 μm or less, still more preferably 0.5 μm or less, and still more preferably 0.4 μm or less. The lower limit of the particle size specified by the requirement (I) is not particularly limited, and is, for example, 0.01 μm or more.

[0066] In this specification, the particle size value specified in the requirement (I) is a value measured by the method described in the Examples below. The particle size value specified in the requirement (I) can be adjusted mainly by the production conditions of the urea-based thickener.

[0067] (Content of urea grease composition (C)) The lubricant according to one embodiment of the present invention contains 5% by mass or more and less than 20% by mass of the urea grease composition (C) relative to 100% by mass of the lubricant, thereby achieving the effect of further reducing torque at room temperature and low temperatures.

[0068] From the viewpoint of improving low-temperature torque at low temperatures, the content of the urea grease composition (C) in the lubricant according to one embodiment of the present invention is preferably 6 mass % or more, more preferably 7 mass % or more, and even more preferably 9 mass % or more, relative to 100 mass % of the lubricant.

[0069] Furthermore, from the viewpoint of preventing deterioration of low-temperature torque at startup, the content of the urea grease composition (C) in the lubricant according to one embodiment of the present invention is preferably 19 mass % or less, more preferably 18 mass % or less, and even more preferably 15 mass % or less, relative to 100 mass % of the lubricant.

[0070] <Other Additives (D)> The lubricant according to one embodiment of the present invention may further contain an additive (D) within a range that does not impair the effects of the present invention. Additives commonly used in lubricants can be used as the additive (D). Examples of such additives include oiliness agents, antioxidants, thickeners, rust inhibitors, dispersants, metal deactivators, extreme pressure agents, wear reducers, and solid lubricants.

[0071] Examples of oily agents include fatty alcohols; fatty acid compounds such as fatty acids and fatty acid metal salts; ester compounds such as fatty acid esters, polyol esters, sorbitan esters, and glycerides; amine compounds such as fatty amines; amide compounds, and aluminum stearate.

[0072] Examples of the antioxidant include amine-based antioxidants such as diphenylamine compounds and naphthylamine compounds; and phenol-based antioxidants such as monocyclic phenol compounds and polycyclic phenol compounds.

[0073] Examples of thickeners include polymethacrylate (PMA), olefin copolymer (OCP), polyalkylstyrene (PAS), and styrene-diene copolymer (SCP).

[0074] Examples of the rust inhibitor include carboxylic acid-based rust inhibitors such as alkenyl succinic acid polyhydric alcohol esters; thiadiazole and derivatives thereof; benzotriazole and derivatives thereof; metal sulfonates such as calcium sulfonate and barium sulfonate; and fatty acid ester-based rust inhibitors such as sorbitan monooleate.

[0075] Examples of the dispersant include ashless dispersants such as succinimide and boron-based succinimide.

[0076] Examples of the metal deactivator include benzotriazole compounds.

[0077] Examples of extreme pressure agents include thiocarbamic acids such as zinc dialkyldithiophosphate, molybdenum dialkyldithiophosphate, ashless dithiocarbamate, zinc dithiocarbamate, and molybdenum dithiocarbamate; sulfur compounds such as sulfurized fats and oils, sulfurized olefins, polysulfides, thiophosphoric acids, thioterpenes, and dialkylthiodipropionates; phosphate esters such as tricresyl phosphate and molybdenum dithiophosphate; and phosphite esters such as triphenyl phosphite.

[0078] Examples of the wear reducer include phosphate esters and dithiocarbamate esters.

[0079] Examples of solid lubricants include polyimide, PTFE, graphite, metal oxides, boron nitride, melamine cyanurate, and molybdenum disulfide.

[0080] These additives may be used alone or in combination of two or more.

[0081] Among these, the lubricant according to an embodiment of the present invention preferably further contains melamine cyanurate, an antioxidant, and aluminum stearate. By including these additives in the lubricant according to an embodiment of the present invention, the effect of further improving stick-slip suppression at low temperatures can be obtained.

[0082] (Content of Additive (D)) When the lubricant according to one embodiment of the present invention contains additive (D), the content of additive (D) is independently 0.01 to 20 mass%, preferably 0.01 to 15 mass%, more preferably 0.01 to 10 mass%, and even more preferably 0.01 to 7 mass%, relative to 100 mass% of the lubricant.

[0083] <Thickener> The lubricant according to one embodiment of the present invention can be a semi-solid substance such as a grease composition without including a thickener. Therefore, the lubricant according to one embodiment of the present invention can contain a lower thickener content than conventional grease compositions. For example, the lubricant according to one embodiment of the present invention may contain 5% by mass or less of the thickener relative to 100% by mass of the lubricant. The lubricant according to one embodiment of the present invention can also be configured to contain no thickener. The lubricant according to one embodiment of the present invention contains a lower thickener content than conventional grease compositions, or does not contain a thickener, so that no reactions occur during production, resulting in increased stability and efficient mass production.

[0084] <Physical Properties of Lubricant> (Worked Penetration) Worked penetration is a parameter that represents the hardness of a lubricant. From the viewpoint of torque reduction at room temperature and low temperatures, the lubricant according to one embodiment of the present invention preferably has a hardness higher than NLGI (National Lubricating Grease Institute) Consistency Grade No. 0. To achieve such hardness, the lubricant according to one embodiment of the present invention preferably has a worked penetration at 25°C of 370 or less, more preferably 360 or less, and even more preferably 340 or less. The lower limit of the worked penetration at 25°C is not particularly limited, but may be 260 or more. In this specification, the worked penetration of a lubricant refers to a value measured at 25°C and 60W according to the method described in JIS K2220:2013.

[0085] (Dropping Point) From the viewpoint of heat resistance, the lubricant according to one embodiment of the present invention preferably has a dropping point of 80 or more, more preferably 90 or more, and even more preferably 100 or more. Although not particularly limited, the dropping point may be 70 or less. In this specification, the dropping point of the lubricant means a value measured in accordance with JIS K2220:2013.

[0086] (Low-Temperature Torque) The lubricant according to one aspect of the present invention has a starting torque at low temperatures of preferably 900 mN m or less, more preferably 600 mN m or less, and a steady-state torque at low temperatures of preferably 800 mN m or less, more preferably 450 mN m or less.

[0087] (Room Temperature Torque) The lubricant according to one aspect of the present invention preferably has a joint torque that is evaluated by the method described in the Examples below as being rated as "A".

[0088] (Suppression of stick-slip at low temperatures) The smaller the difference between the starting torque and steady-state torque at low temperatures, the less likely stick-slip will occur at low temperatures, which is preferable. For this reason, the lubricant according to one aspect of the present invention has a difference between the starting torque and steady-state torque at low temperatures of preferably 450 mN m or less, more preferably 350 mN m or less, and even more preferably 250 mN m or less.

[0089] <Method for producing lubricant> The lubricant according to one embodiment of the present invention can be produced by mixing the liquid polyolefin wax (A), the amide compound (B), and, if necessary, the urea grease composition (C) and the additive (D), maintaining the resulting mixture at a predetermined temperature, and then slowly cooling it.

[0090] As an example, as described in the Examples below, a lubricant according to one embodiment of the present invention can be produced by mixing a liquid polyolefin wax (A), an amide compound (B), and, if necessary, a urea grease composition (C) and an additive (D), raising the temperature of the resulting mixture to 150°C over about 60 minutes while stirring, holding the mixture at 150°C for 10 minutes, and then slowly cooling the mixture while maintaining stirring. The holding temperature and holding time of the mixture of lubricant raw materials can be appropriately adjusted in order to dissolve the mixture; for example, the holding temperature can be 100°C to 160°C, and the holding time can be 5 to 60 minutes.

[0091] <Uses of Lubricant> The lubricant according to one embodiment of the present invention has good friction characteristics at room temperature and at low temperature, and therefore can be suitably used for lubricating sliding parts of various devices.

[0092] The lubricant according to one aspect of the present invention can be suitably used, for example, for lubricating mechanical parts that involve lubrication between resin and metal. Thus, the lubricant according to one aspect of the present invention can be used as a lubricant for mechanical parts that involve lubrication between resin and metal.

[0093] The resin material constituting the mechanical component may be a natural resin or a synthetic resin, but general-purpose synthetic plastics (polyethylene, polystyrene, polypropylene, polyvinyl chloride, etc.) and engineering plastics are preferred, and from the viewpoints of heat resistance and mechanical strength, engineering plastics are more preferred.

[0094] Examples of engineering plastics include synthetic resins such as polyamide resin, polyacetal resin, polycarbonate resin, polysulfone resin, polyphenylene sulfide resin, polyamideimide resin, polyether ether ketone resin, phenol resin, polyester resin, and epoxy resin.

[0095] The metal material constituting the machine part is preferably various alloys such as stainless steel alloys and aluminum alloys; copper; etc. The metal material may be replaced with a material having high strength (for example, ceramic material).

[0096] Examples of mechanical parts involving lubrication between resin and metal, for which the lubricant according to one embodiment of the present invention can be suitably used, include bearing parts within devices such as radiator fan motors, fan couplings, alternators, idler pulleys, hub units, water pumps, power windows, wipers, electric power steering, electric drive motor flywheels, ball joints, wheel bearings, spline parts, and constant velocity joints; bearing parts, gear parts, and sliding parts within devices such as door locks, door hinges, and clutch boosters; etc. These are mainly used as lubricating parts within devices in the automotive field.

[0097] In addition to the automotive field, fields of equipment in which the lubricant according to one embodiment of the present invention can be suitably used include the field of office equipment, machine tools, wind turbines, construction or agricultural machinery, and the like.

[0098] Examples of lubricated parts in devices in the field of office equipment include a fixing roll in a device such as a printer, and bearings and gear parts in a device such as a polygon motor.

[0099] Examples of parts that need to be lubricated in devices in the field of machine tools include bearing parts in reducers of spindles, servo motors, machine tool robots, and the like.

[0100] Lubricated parts in devices in the wind turbine field include, for example, bearing parts such as blade bearings and generators.

[0101] Examples of parts that need to be lubricated in equipment in the fields of construction or agricultural machinery include bearing parts such as ball joints and spline parts, gear parts, and sliding parts.

[0102] [2. Lubrication Method Using a Lubricant According to an Aspect of the Present Invention] A lubrication method using a lubricant according to an aspect of the present invention to lubricate a mechanical part involving lubrication between resin and metal is also included in the scope of the present invention. According to a lubrication method using a lubricant according to an aspect of the present invention, friction characteristics are good at room temperature and at low temperature, so that when used in a vehicle, excellent ride comfort and fuel economy can be achieved. In particular, in electric vehicles, the fuel efficiency improvement effect is remarkable because power consumption can be reduced.

[0103] [Summary] According to one aspect of the present invention, the following [1] to [6] are provided. [1] A lubricant containing, relative to 100 mass% of the lubricant, 40 mass% or more of a liquid polyolefin wax (A) and 20 mass% or more of an amide compound (B). [2] The lubricant according to [1], further containing a urea grease composition containing a base oil and a urea-based thickener, wherein the content of the urea grease composition in the lubricant is 5 mass% or more but less than 20 mass%, and particles containing the urea-based thickener in the urea grease composition satisfy the following requirement (I): Requirement (I): The particles have an area-based arithmetic mean particle diameter of 2.0 μm or less when measured by a laser diffraction / scattering method. [3] The lubricant according to [1] or [2], wherein the amide compound (B) is at least one amide compound selected from the group consisting of saturated fatty acid amides (B1) and unsaturated fatty acid amides (B2). [4] The lubricant according to any one of [1] to [3], wherein the amide compound (B) comprises ethylene bisstearamide (B1) and ethylene bisoleamide (B2). [5] The lubricant according to any one of [1] to [4], further comprising melamine cyanurate, an antioxidant, and aluminum stearate. [6] The lubricant according to any one of [1] to [5], which is a lubricant for machine parts that lubricate resin and metal.

[0104] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0105] The present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

[0106] [Various Physical Properties] Various physical properties were measured as follows: (1) Worked Penetration of Lubricant Measured according to the method described in JIS K2220:2013 (25°C, 60W).

[0107] (2) Dropping point of lubricant: Measured in accordance with JIS K2220:2013.

[0108] (3) Joint Torque The joint torque was evaluated using a ball joint testing machine. Fig. 1 is a schematic diagram showing the configuration of the ball joint testing machine 1 used in the examples. For ease of explanation, Fig. 1 shows a cross section of the ball joint 11 taken along the X axis.

[0109] The ball joint testing machine 1 shown in FIG. 1 includes a ball joint 11 having a resin housing 111 and a metal (SUJ-2) ball stud 112. The housing 111 is connected to a servo motor 12 so that it has an axis in the X direction and can rotate at any angle around the X axis. The metal ball stud 112 has an axis in the Z direction and is connected to an arm 14 of a torque cell 13. The diameter of the ball portion of the metal ball stud 112 is 16 mm. By changing the load 15, any load can be applied to the metal ball stud 112.

[0110] A polyacetal (POM) sheet 16 was laid inside the housing 111, and 0.3 g of lubricant 17 was applied to the sheet 16 to a uniform thickness. After that, a metal ball stud 112 was fitted inside the housing 111, and the ball joint 11 was connected to the ball joint testing machine 1.

[0111] Next, without controlling the temperature, a test piece (the ball stud 112 was treated as a test piece and was disposable) was placed in the ball joint testing machine 1 in a room temperature environment. After 10 minutes had elapsed, the position where the top surface of the housing 111 was horizontal was defined as 0°, and the torque was measured under the following conditions when tilted around the X axis from -10° to +10°. The waveform of the torque versus angle around the X axis was recorded for each reciprocation, and this was repeated until 20 reciprocations had been completed.

[0112] The absolute value of the maximum torque for each cycle was calculated from the Lissajous waveform obtained at the 20th cycle, and the average value for the 20 cycles was determined as the starting torque. The absolute value of the torque for each cycle was also calculated, and the average value for 10 cycles was determined as the steady-state torque. <Measurement conditions> Angle: ±10° Load: 0 kg Frequency: 0.1 Hz Cycle: 20.

[0113] The joint torque was evaluated according to the following evaluation criteria. In the evaluation criteria below, evaluation "A" is the highest evaluation, and the evaluation decreases in the order of evaluation "B" and evaluation "C." Evaluation "A" was evaluated as having good friction characteristics at room temperature. <Evaluation criteria> A: 1 to 3 mNcm B: 3 to 5 mNcm C: 5 to 8 mNcm

[0114] (4) Low-Temperature Torque The starting torque (unit: mN m) and steady-state torque (unit: mN m) at low temperatures were determined in accordance with JIS K2220: 2013. In addition, to evaluate the stick-slip suppression ability, the difference between the starting torque and steady-state torque at low temperatures was calculated.

[0115] (5) Particle size of particles containing a urea-based thickener: Requirement (I) Using a urea grease composition as a measurement sample, the particle size of particles containing a urea-based thickener in the urea grease composition was determined according to the following procedure.

[0116] First, the measurement sample was vacuum degassed and then loaded into a 1 mL syringe. 0.10 to 0.15 mL of the sample was extruded from the syringe, and the extruded sample was placed on the surface of a plate-shaped cell of a paste cell fixture. Next, another plate-shaped cell was placed on top of the sample to obtain a measurement cell in which the sample was sandwiched between the two cells. Next, the arithmetic mean particle size of the particles in the sample in the measurement cell was measured on an area basis using a laser diffraction particle size analyzer (manufactured by Shimadzu Corporation, product name: LA-920).

[0117] Here, "area-based arithmetic mean particle diameter" means the arithmetic mean of the area-based particle diameter distribution. The area-based particle diameter distribution indicates the frequency distribution of particle diameters of all particles to be measured, based on the area calculated from the particle diameters (more specifically, the cross-sectional area of ​​particles having the particle diameters). The arithmetic mean of the area-based particle diameter distribution can be calculated using the following formula (1): In the formula (1), J represents the particle size division number, q(J) represents the frequency distribution value (unit: %), and X(J) represents the representative diameter (unit: μm) of the Jth particle size range.

[0118] [Raw Materials] In the Examples and Comparative Examples, the raw materials used to prepare the lubricants were as follows.

[0119] <Liquid Polyolefin Wax (A)> Liquid polyethylene wax (manufactured by Shamrock, trade name: VALSE FLOW EV, 395 mm) ２ / s (40℃ kinematic viscosity), 40mm ２ / s (100℃ kinematic viscosity), viscosity index VI 149)

[0120] <Base oil> Poly-α-olefin (PAO) 40°C kinematic viscosity 400 mm ２ / s

[0121] <Amide Compound (B)> <Saturated Fatty Acid Amides (B1)> Ethylene bisstearamide (B11) (manufactured by Kao Corporation, trade name: Kaowax EB-G, melting point: 142 to 147°C) Ethylene bisstearamide (B12) (manufactured by NOF Corporation, trade name: Alflow H50S, melting point: 140 to 145°C) <Unsaturated Fatty Acid Amides (B2)> Ethylene bisoleamide (B21) (manufactured by NOF Corporation, trade name: Alflow AD-281F, melting point: 115°C) Oleamide (B22) (manufactured by Lion Specialty Chemicals Co., Ltd., trade name: Armoslip CP Powder, melting point: 72 to 76°C)

[0122] <Nanourea-based grease (C)> Nanourea-based grease 1 [Base oil: Group III base oil (kinematic viscosity at 40°C: 17 mm ２ / s) + mineral oil (40℃ kinematic viscosity 400mm ２ / s), alicyclic urea; particle size of particles containing a urea-based thickener: 1 μm] Nanourea-based grease 2 [base oil: PAO (kinematic viscosity at 40 ° C.: 63 mm ２ / s) + PAO (40℃ kinematic viscosity 400mm ２ / s), aliphatic alicyclic urea; particle size of particles containing a urea-based thickener: 2 μm] Nanourea-based grease 1 and nanourea-based grease 2 are mixtures of base oil and thickener, and are "base greases" that do not contain additives.

[0123] (Method for Producing Nanourea-Based Grease 1) 3.16 parts of diphenylmethane-4,4'-diisocyanate (MDI) was added to a mixed base oil of 34.28 parts by mass of Group III base oil and 12.65 parts by mass of mineral oil heated to 70°C to prepare solution α.

[0124] Separately, a mixed base oil of 33.4 parts by mass of Group III base oil and 12.65 parts by mass of mineral oil was heated to 70°C, and 2.0 parts by mass of cyclohexylamine and 1.36 parts by mass of octadecylamine (stearylamine) were added to prepare solution β.

[0125] Using the nanourea-based grease production apparatus 21 shown in Figure 2, equal amounts of solution α heated to 70°C were introduced into the container body 22 through the solution inlet pipe 4A, and solution β heated to 70°C was introduced into the container body 22 through the solution inlet pipe 4B. While the rotor 23 was rotating, solution α and solution β were continuously introduced into the container body 22. The mixture was then heated to 160°C using a stirrer, stirred for 1 hour, and then allowed to cool naturally to 100°C. 0.5 parts by mass of an amide compound was then added, and the mixture was homogenized by roll milling, to synthesize nanourea-based grease 1.

[0126] The rotation speed of the rotor 23 of the nanourea-based grease manufacturing apparatus 21 used was 8,000 rpm. The maximum shear rate (Max) was 10,500 s －１ The stirring was carried out with the ratio of the maximum shear rate (Max) to the minimum shear rate (Min) [Max / Min] set to 3.5.

[0127] The urea-based thickener contained in the obtained nanourea-based grease 1 is represented by the formula (b1) R １ and R ２ is a cyclohexyl group or an octadecyl group (stearyl group), and R ３ corresponds to a compound in which R is a diphenylmethylene group. １ -NHCONH-R ３ -NHCONH-R ２ ...(b1) [In the general formula (b1), R １ and R ２ R each independently represents a monovalent hydrocarbon group having 6 to 24 carbon atoms. １ and R ２ may be the same or different from each other. ３ represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms.]

[0128] The molar ratio of cyclohexylamine to octadecylamine used as raw materials (cyclohexylamine / octadecylamine) was 80 / 20.

[0129] (Nanourea-based grease 2 manufacturing method) A PAO-based base oil (kinematic viscosity at 40°C: 63 mm) heated to 70°C was used. ２ / s) 29.45 parts by mass, and PAO base oil (kinematic viscosity at 40 ° C. 400 mm ２ A solution α was prepared by adding 5.84 parts by mass of diphenylmethane-4,4'-diisocyanate (MDI) to 15.00 parts by mass of the mixed base oil (aqueous solvent).

[0130] In addition, a PAO-based base oil (kinematic viscosity at 40°C: 63 mmHg) heated to 70°C was used. ２ / s) 33 parts by mass, PAO base oil (kinematic viscosity at 40 ° C. 400 mm ２ Solution β was prepared by adding 3.7 parts by mass of cyclohexylamine and 2.51 parts by mass of octadecylamine (stearylamine) to 10.00 parts by mass of the mixed base oil (C10-C12).

[0131] 2, equal amounts of solution α heated to 70°C were introduced into the container body 22 through the solution inlet pipe 4A, and solution β heated to 70°C was introduced into the container body 22 through the solution inlet pipe 4B. While the rotor 23 was rotating, solution α and solution β were continuously introduced into the container body 22. The mixture was then heated to 160°C using a stirrer, stirred for 1 hour, and then allowed to cool naturally to 100°C. 0.5 parts by mass of an amide compound was then added, and the mixture was homogenized by roll milling, to synthesize nanourea-based grease 2.

[0132] The rotation speed of the rotor 23 of the nanourea-based grease manufacturing apparatus 21 used was 8,000 rpm. The maximum shear rate (Max) was 10,500 s －１ The stirring was carried out with the ratio of the maximum shear rate (Max) to the minimum shear rate (Min) [Max / Min] set to 3.5.

[0133] The urea-based thickener contained in the obtained nanourea-based grease 2 is represented by the formula (b1) R １ and R ２ is a cyclohexyl group or an octadecyl group (stearyl group), and R ３ corresponds to a compound in which is a diphenylmethylene group.

[0134] The molar ratio of cyclohexylamine to octadecylamine used as raw materials (cyclohexylamine / octadecylamine) was 80 / 20.

[0135] <Other Additives (D)> Melamine cyanurate (manufactured by Sakai Chemical Industry Co., Ltd., trade name: MC-2010N) Phenol-based antioxidant (manufactured by BASF, trade name: IRGANOX L-135) Aluminum stearate (manufactured by NOF Corporation, trade name: Al Stearate #300)

[0136] [Example 1] The components were blended according to the blending ratios shown in Table 1, and the mixture was heated to 150°C over approximately 60 minutes while stirring, and then held at 150°C for 10 minutes. The mixture was then slowly cooled while continuing to stir, yielding the lubricant of Example 1. The blend amounts in the table are in mass%. A blank space in the blend amount column indicates that the component was not added.

[0137] [Examples 2 to 6, Comparative Examples 1 to 5] Lubricants of Examples 2 to 6 and Comparative Examples 1 to 5 were obtained in the same manner as in Example 1, except that the components were blended according to the blending ratios shown in Table 1 or Table 2.

[0138] <Evaluation Results> For each of the lubricants of Examples 1 to 6 and Comparative Examples 1 to 5, the worked penetration, dropping point, joint torque, and low-temperature torque of the lubricant were measured.

[0139] The results are shown in Tables 1 and 2.

[0140]

[0141] The results shown in Tables 1 and 2 indicate that the lubricants of Examples 1 to 6, which contain a specific amount of amide compound (B) in liquid polyolefin (A), have good friction properties at room temperature and at low temperatures.

[0142] Furthermore, a comparison between Example 1 and Example 2 showed that the lubricant containing the nanourea grease composition (C) had lower low-temperature torque at startup and steady state and better friction characteristics at low temperatures than the lubricant not containing the nanourea grease composition (C).

[0143] Furthermore, a comparison between Example 2 and Example 3 showed that the lubricant containing both ethylene bisstearamide (B1) and ethylene bisoleamide (B2) as the amide compound (B) had a smaller difference between the starting torque and the steady-state torque at low temperatures than a lubricant containing either ethylene bisstearamide (B1) or ethylene bisoleamide (B2), and therefore had better stick-slip suppression properties.

[0144] Furthermore, a comparison between Example 3 and Example 4 showed that the lubricant further containing melamine cyanurate, an antioxidant, and aluminum stearate as other additives (D) had a smaller difference between the starting torque and steady-state torque at low temperatures, and therefore better stick-slip suppression properties, compared to a lubricant not containing these additives.

[0145] The present invention can be suitably used as a lubricant for machine parts that involve lubrication between resin and metal, such as ball joints.

[0146] 1 Ball joint testing machine, 11 Ball joint, 12 Servo motor, 13 Torque cell, 14 Arm, 15 Load, 16 Seat, 17 Lubricant, 111 Housing, 112 Ball stud, 21 Nanourea-based grease manufacturing device, 22 Main container, 23 Rotor, 4A, 4B Solution introduction tube

Claims

1. A lubricant containing, relative to 100% by mass of the lubricant, 40% by mass or more of a liquid polyolefin wax (A) and 20% by mass or more of an amide compound (B).

2. A lubricant according to claim 1, further comprising a urea grease composition containing a base oil and a urea-based thickener, wherein the content of the urea grease composition in the lubricant is 5 mass% or more and less than 20 mass%, and the particles containing the urea-based thickener in the urea grease composition satisfy the following requirement (I): Requirement (I): The arithmetic mean particle diameter on an area basis when the particles are measured by a laser diffraction / scattering method is 2.0 μm or less.

3. The lubricant according to claim 1 or 2, wherein the amide compound (B) is at least one amide compound selected from the group consisting of saturated fatty acid amides (B1) and unsaturated fatty acid amides (B2).

4. The lubricant according to any one of claims 1 to 3, wherein the amide compound (B) comprises ethylene bisstearic acid amide (B1) and ethylene bisoleic acid amide (B2).

5. The lubricant of any one of claims 1 to 4, further comprising melamine cyanurate, an antioxidant, and aluminum stearate.

6. The lubricant according to any one of claims 1 to 5, which is a lubricant for machine parts that lubricate resin and metal.

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