Lubricating oil composition

Abstract

Provided is a lubricating oil composition containing a base oil (A) having a NOACK value of 6 mass% or less, the NOACK value being measured by a NOACK test performed in accordance with ASTM D5800 at 250 DEG C for 1 hour, the CCS viscosity at-25 DEG C being 7000 mPa.s or less, and the HTHS viscosity at 150 DEG C being 2.9 mPa.s or more.

Description

Technical Field

[0001] The present invention relates to a lubricating oil composition and a method for lubricating an internal combustion engine. Background Art

[0002] Internal combustion engines used in automobiles and the like are subject to various demands such as miniaturization and high output, fuel economy, and compliance with exhaust gas regulations, and lubricating oil compositions used in internal combustion engines are being developed to cope with such demands.

[0003] For example, Patent Document 1 discloses a lubricating oil composition for an internal combustion engine, which is intended to provide a lubricating oil composition for an internal combustion engine that can suppress a decrease in base number and suppress the occurrence of coking and copper elution. The composition contains a lubricating oil base oil, a predetermined amount of boron-containing alkenyl succinimide and / or boron-containing alkyl succinimide in terms of boron, and a poly(meth)acrylate having a weight average molecular weight and an average carbon number of an alkyl group within a predetermined range.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-196696 Summary of the invention

[0007] Problems to be solved by the invention

[0008] Under such circumstances, there is a demand for a lubricating oil composition having various properties and being suitably used in an internal combustion engine.

[0009] Solutions to Solve Problems

[0010] The present inventors have made repeated efforts and have provided, as one embodiment, a lubricating oil composition using a base oil having a NOACK value of a specified value and having a CCS viscosity at -25°C and a HTHS viscosity at 150°C adjusted to a specified range. Specifically, one embodiment of the present invention is disclosed below.

[0011] [1] A lubricating oil composition comprising a base oil (A) having a NOACK value of 6% by mass or less, wherein the NOACK value is a value measured by a NOACK test conducted at 250° C. for 1 hour in accordance with ASTM D5800,

[0012] The lubricating oil composition has a CCS viscosity at -25°C of 7000 mPa·s or less,

[0013] The lubricating oil composition has a HTHS viscosity at 150° C. of 2.9 mPa·s or more.

[0014] [2] A method for lubricating an internal combustion engine, comprising applying the lubricating oil composition described in [1] above to lubricate the internal combustion engine.

[0015] [3] A lubricating oil composition comprising: a base oil (A) having a NOACK value of 6% by mass or less, the NOACK value being a value measured by a NOACK test conducted at 250° C. for 1 hour in accordance with ASTM D5800, and

[0016] A calcium detergent (B), the calcium detergent (B) comprising at least calcium salicylate (B1), and optionally comprising at least one selected from a neutral calcium sulfonate (B2) having a base value of 70 mgKOH / g or less and a calcium phenate (B3),

[0017] The ratio of the content (b2) of the neutral calcium sulfonate (B2) in terms of calcium atoms to the content (b) of the calcium-based detergent (B) in terms of calcium atoms [(b2) / (b)] is 0 to 0.40,

[0018] The ratio of the content (b3) of the calcium phenate (B3) in terms of calcium atoms to the content (b) of the calcium-based detergent (B) in terms of calcium atoms [(b3) / (b)] is 0 to 0.02,

[0019] The lubricating oil composition has a CCS viscosity at -25°C of 7000 mPa·s or less,

[0020] The lubricating oil composition has a HTHS viscosity at 150° C. of 2.9 mPa·s or more,

[0021] The lubricating oil composition is used in an internal combustion engine which operates with hydrogen as fuel.

[0022] [4] A method for lubricating an internal combustion engine, comprising applying the lubricating oil composition according to [3] above to lubricate an internal combustion engine that is operated using hydrogen as fuel.

[0023] Effects of the Invention

[0024] A lubricating oil composition according to a preferred embodiment of the present invention has various properties and can be suitably used for lubrication of internal combustion engines. For example, a lubricating oil composition according to a preferred embodiment of the present invention has a high effect of suppressing the occurrence of coking in a high temperature environment. In addition, a lubricating oil composition according to another preferred embodiment of the present invention has properties such as emulsification resistance that can be suitably used for internal combustion engines that operate using hydrogen as fuel. DETAILED DESCRIPTION

[0025] For the numerical ranges described in this specification, the upper limit and the lower limit may be arbitrarily combined. For example, when the numerical range is described as "preferably 30 to 100, more preferably 40 to 80", the ranges of "30 to 80" and "40 to 100" are also included in the numerical ranges described in this specification.

[0026] In addition, for example, when a numerical range is described as "preferably 30 or more, more preferably 40 or more, and preferably 100 or less, more preferably 80 or less", a range such as "30 to 80" and a range such as "40 to 100" are also included in the numerical range described in this specification. That is, in the provisions of the upper limit and the lower limit described in this specification, the numerical range from the lower limit to the upper limit can be specified by appropriately selecting from the respective options and arbitrarily combining them.

[0027] Furthermore, as a numerical range described in the present specification, for example, the description of "60 to 100" means a range of "60 or more (60 or more) and 100 or less (100 or less)".

[0028] Furthermore, as preferred embodiments described in this specification, various requirements described may be combined in multiple ways.

[0029] [Constitution of Lubricating Oil Composition]

[0030] A lubricating oil composition according to one embodiment of the present invention contains a base oil (A) having a NOACK value of 6 mass % or less, and satisfies the following requirements (I) and (II).

[0031] Requirement (I): CCS viscosity at -25°C is 7000 mPa·s or less.

[0032] Requirement (II): HTHS viscosity at 150°C is 2.9 mPa·s or more.

[0033] In recent years, there has been a demand for a lubricating oil composition that has a high effect of suppressing the occurrence of coking in a high-temperature environment and can be suitably used in an internal combustion engine.

[0034] In order to solve such a problem, a lubricating oil composition according to one embodiment of the present invention contains a base oil (A) having a NOACK value of 6 mass % or less and is adjusted so as to satisfy the above-mentioned requirements (I) and (II), thereby achieving a lubricating oil composition that has a high effect of suppressing the occurrence of coking in a high temperature environment and can be suitably used in an internal combustion engine.

[0035] By making a lubricating oil composition satisfying requirement (I), the startability of the engine at low temperature becomes good. A lubricating oil composition having a CCS viscosity at -25°C of more than 7000 mPa·s tends to have insufficient startability of the engine under low temperature environment.

[0036] In addition, in this specification, the CCS viscosity at -25°C means a value measured at -25°C according to ASTM D5293.

[0037] By making a lubricating oil composition satisfying requirement (II), the oil film can be easily maintained even at high temperatures, and the wear resistance becomes good. A lubricating oil composition having a HTHS viscosity at 150°C of less than 2.9 mPa·s tends to be poor in wear resistance.

[0038] From the viewpoint of providing a lubricating oil composition having improved oil film retention in a high temperature environment and excellent wear resistance, the HTHS viscosity at 150° C. of the lubricating oil composition of one embodiment of the present invention is preferably 3.0 mPa·s or more, more preferably 3.2 mPa·s or more.

[0039] In this specification, the HTHS viscosity at 150°C refers to a value measured at 150°C in accordance with ASTM D4683.

[0040] In addition, in recent years, the development of automobiles equipped with hydrogen fuel engines has been carried out, and lubricating oil compositions suitable for lubrication of hydrogen fuel engines are required. Hydrogen fuel engines use hydrogen as fuel, so water is generated. Sometimes the lubricating oil composition is emulsified due to the mixing of this water. The hydrogen fuel engine needs to discharge the generated water to the outside of the vehicle, but if it is emulsified, it becomes difficult to discharge. In addition, due to emulsification, the viscosity of the lubricating oil composition is increased, which also becomes a cause of engine equipment failure. Therefore, a lubricating oil composition is required, which has suitable properties for internal combustion engines running with hydrogen as fuel, such as emulsification resistance.

[0041] In order to solve such a problem, a lubricating oil composition according to one embodiment of the present invention can be a lubricating oil composition having good emulsification resistance and suitable for use in an internal combustion engine operated with hydrogen as fuel by further containing a calcium-based detergent (B), wherein the calcium-based detergent (B) contains at least calcium salicylate (B1) and can optionally contain one or more selected from a neutral calcium sulfonate (B2) having a base value of 70 mgKOH / g or less and a calcium phenate (B3).

[0042] The lubricating oil composition according to one embodiment of the present invention may further contain a viscosity index improver (C).

[0043] The lubricating oil composition of one embodiment of the present invention may further contain other lubricating oil additives in addition to the above-mentioned components (B) and (C) within a range not impairing the effects of the present invention.

[0044] Hereinafter, the details of each component contained in the lubricating oil composition according to one embodiment of the present invention will be described.

[0045] <Ingredient (A): Base oil>

[0046] The base oil (A) used in one embodiment of the present invention may be one or more selected from mineral oils and synthetic oils.

[0047] Examples of the mineral oil include atmospheric residues obtained by subjecting crude oils such as paraffinic crude oil, intermediate crude oil, and cycloparaffinic crude oil to atmospheric distillation; distillates obtained by subjecting these atmospheric residues to vacuum distillation; and refined oils obtained by subjecting the distillates to one or more of the refining treatments selected from solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrofinishing.

[0048] Examples of synthetic oils include poly-α-olefins such as α-olefin homopolymers and α-olefin copolymers (e.g., α-olefin copolymers having 8 to 14 carbon atoms, such as ethylene-α-olefin copolymers); isoparaffins; polyalkylene glycols; ester oils such as polyol esters, dibasic acid esters, and phosphate esters; ether oils such as polyphenylene ethers; alkylbenzenes; alkylnaphthalenes; synthetic oils (GTL) obtained by isomerizing wax produced from natural gas using the Fischer-Tropsch process, etc. (GTL wax (Gas To Liquids WAX)); and the like.

[0049] The base oil (A) used in one embodiment of the present invention has a NOACK value of 6% by mass or less. By using a base oil (A) having a NOACK value of 6% by mass or less, it is difficult to atomize even when used in a high temperature environment, and the amount of coking caused by the atomized components can be suppressed. As a result, a lubricating oil composition with a high inhibitory effect on the occurrence of coking in a high temperature environment can be prepared, and for example, it can also be suitable for use in an internal combustion engine that runs on hydrogen as a fuel. On the other hand, if the NOACK value of the base oil (A) used exceeds 6% by mass, the prepared lubricating oil composition tends to be easily atomized and easily coked in a high temperature environment.

[0050] From the viewpoint of providing a lubricating oil composition with further improved anti-mist properties and a higher effect of suppressing the occurrence of coking, the base oil (A) used in one embodiment of the present invention may have a NOACK value of 5% by mass or less, less than 5% by mass, 4% by mass or less, less than 4% by mass, 3% by mass or less, or less than 3% by mass.

[0051] The NOACK value of the base oil (A) can be adjusted, for example, by removing a light fraction by distillation.

[0052] In this specification, the NOACK value refers to a value measured under the conditions of 250° C. and 1 hour in accordance with ASTM D5800.

[0053] The base oil (A) used in one embodiment of the present invention preferably has a kinematic viscosity at 40° C. of 20 mm 2 / s or more, more preferably 25mm 2 / s or more, more preferably 30mm 2 / s or more, more preferably 32mm 2 / s or more, more preferably 34mm 2 / s or more, particularly preferably 35mm 2 / s or more, preferably 120mm 2 / s or less, more preferably 100mm 2 / s or less, more preferably 80mm 2 / s or less, more preferably 60mm 2 / s or less.

[0054] That is, the kinematic viscosity at 40° C. of the base oil (A) used in one embodiment of the present invention can be 32 to 120 mm 2 / s, 34~100mm 2 / s, 35~80mm 2 / s or 35~60mm 2 / s, can also be set to 20mm 2 / s~120mm 2 / s, 25~100mm 2 / s, 30~80mm 2 / s or 35~60mm 2 / s.

[0055] In this specification, the kinematic viscosity refers to a value measured according to ASTM D445.

[0056] The viscosity index of the base oil (A) used in one embodiment of the present invention is preferably 80 or more, more preferably 100 or more, further preferably 110 or more, and further preferably 120 or more.

[0057] In this specification, the viscosity index refers to a value calculated according to ASTM D2270.

[0058] It should be noted that the base oil (A) used in one embodiment of the present invention may be a single base oil or a mixed oil obtained by combining two or more base oils. When a mixed oil is used, the NOACK value of the mixed oil only needs to be within the above range. Therefore, the mixture may be a combination of base oils having a NOACK value of 6% by mass or less, or a combination of a base oil having a NOACK value of 6% by mass or less and a base oil having a NOACK value of more than 6% by mass.

[0059] Furthermore, it is preferred that the kinematic viscosity and viscosity index of the mixed oil be within the above ranges.

[0060] In the lubricating oil composition of one embodiment of the present invention, the content of the base oil (A) may be 60% by mass or more, 65% by mass or more, 70% by mass or more, 75% by mass or more, or 80% by mass or more, and may be 99.9% by mass or less, 99.5% by mass or less, 99.0% by mass or less, 97.0% by mass or less, 95.0% by mass or less, 92.0% by mass or less, or 90.0% by mass or less, based on the total amount (100% by mass) of the lubricating oil composition.

[0061] <Ingredient (B): Calcium-based detergent>

[0062] The lubricating oil composition of one embodiment of the present invention may contain a calcium-based detergent (B), wherein the calcium-based detergent (B) includes at least calcium salicylate (B1) and may optionally include at least one selected from a neutral calcium sulfonate (B2) having a base value of 70 mgKOH / g or less and a calcium phenate (B3).

[0063] By containing calcium salicylate (B1) as the calcium-based detergent (B), a lubricating oil composition having improved emulsification resistance can be obtained.

[0064] An internal combustion engine that runs on hydrogen as fuel (hereinafter also referred to as a "hydrogen fuel engine") generates water because it uses hydrogen as fuel. The mixing of this water sometimes causes the lubricating oil composition to emulsify. The hydrogen fuel engine needs to discharge the generated water to the outside of the vehicle, but if it is emulsified, it becomes difficult to discharge. In addition, due to emulsification, the viscosity of the lubricating oil composition increases, which also becomes a cause of engine equipment failure. In contrast, the lubricating oil composition of one embodiment of the present invention improves emulsification resistance by containing calcium salicylate (B1), so that the viscosity increase caused by the mixing of water is highly suppressed, and it can be suitably used in hydrogen fuel engines.

[0065] The lubricating oil composition of one embodiment of the present invention may contain, as the calcium detergent (B), a neutral calcium sulfonate (B2) and / or a calcium phenate (B3) having a base value of 70 mgKOH / g or less together with the calcium salicylate (B1).

[0066] In the lubricating oil composition of one embodiment of the present invention, the calcium atom-equivalent content (b) of the calcium-based detergent (B) can be, for example, 1500 mass ppm or more, 2000 mass ppm or more, or 2300 mass ppm or more, and can be 2800 mass ppm or less, based on the total amount (100 mass %) of the lubricating oil composition.

[0067] In this specification, the content of calcium atoms refers to a value measured according to ASTM D5185.

[0068] 《Calcium Salicylate (B1)》

[0069] As calcium salicylate (B1) used in one embodiment of the present invention, there can be mentioned, for example, a compound represented by the following general formula (b-1).

[0070] [Chemical formula 1]

[0071]

[0072] In the above general formula (b-1), R is independently a hydrocarbon group having 1 to 18 carbon atoms.

[0073] Examples of the hydrocarbon group that can be selected as R include alkyl groups having 1 to 18 carbon atoms.

[0074] The calcium salicylate (B1) used in one embodiment of the present invention may be a highly basic calcium salicylate (B11) having a base value of 100 mgKOH / g or more, or a neutral calcium salicylate (B12) having a base value of less than 100 mgKOH / g, or these may be used in combination.

[0075] In addition, in this specification, the base number means the value measured by the perchloric acid method based on ASTM D2896.

[0076] The base value of the overbased calcium salicylate (B11) used in one embodiment of the present invention can be 120 mgKOH / g or more, 150 mgKOH / g or more, 170 mgKOH / g or more, or 200 mgKOH / g or more, and can be 400 mgKOH / g or less, or 350 mgKOH / g or less.

[0077] The base value of the neutral calcium salicylate (B12) used in one embodiment of the present invention can be 0 mgKOH / g or more, 10 mgKOH / g or more, 20 mgKOH / g or more, 30 mgKOH / g or more, or 40 mgKOH / g or more, and can be 70 mgKOH / g or less.

[0078] In the lubricating oil composition of one embodiment of the present invention, the ratio of the content (b1) of the calcium salicylate (B1) in terms of calcium atom to the content (b) of the calcium-based detergent (B) in terms of calcium atom [(b1) / (b)] can be 0.60 or more, 0.65 or more, or 0.70 or more, and can be 1.00 or less, 0.95 or less, 0.90 or less, or 0.85 or less.

[0079] In the lubricating oil composition of one embodiment of the present invention, the content of the overbased calcium salicylate (B11) is 0.1 mass% or more, 0.5 mass% or more, 1.0 mass% or more, 1.5 mass% or more, or 1.7 mass% or more, and is 10.0 mass% or less, 7.0 mass% or less, 5.0 mass% or less, or 4.0 mass% or less, based on the total amount (100 mass%) of the lubricating oil composition.

[0080] In the lubricating oil composition of one embodiment of the present invention, the content of neutral calcium salicylate (B12) is 1.0 mass% or more, 3.0 mass% or more, 5.0 mass% or more, 7.0 mass% or more, or 9.0 mass% or more, and is 20.0 mass% or less, 17.0 mass% or less, 15.0 mass% or less, or 12.0 mass% or less, based on the total amount (100 mass%) of the lubricating oil composition.

[0081] 《Neutral calcium sulfonate (B2)》

[0082] The lubricating oil composition of one embodiment of the present invention may contain a neutral calcium sulfonate (B2) having a base value of 70 mgKOH / g or less as the calcium-based detergent (B).

[0083] The ratio of the calcium atom-equivalent content (b2) of the neutral calcium sulfonate (B2) to the calcium atom-equivalent content (b) of the calcium-based detergent (B) [(b2) / (b)] is preferably 0 to 0.40.

[0084] In the case of a lubricating oil composition having the ratio [(b2) / (b)] of more than 0.40, a decrease in emulsification resistance is observed, and there is a concern that viscosity increase may occur due to mixing of water.

[0085] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition with further improved emulsification resistance, the ratio [(b2) / (b)] may be 0.40 or less, 0.35 or less, or 0.30 or less, and may be 0 or more, 0.05 or more, or 0.10 or more. From the viewpoint of particularly improving emulsification resistance, it is preferably 0.15 or more, and more preferably 0.20 or more.

[0086] The neutral calcium sulfonate (B2) used in one embodiment of the present invention has a base value of 70 mgKOH / g or less, and can be 0 mgKOH / g or more, 10 mgKOH / g or more, 20 mgKOH / g or more, 30 mgKOH / g or more, or 40 mgKOH / g or more.

[0087] As the neutral calcium sulfonate used in one embodiment of the present invention, for example, there can be mentioned compounds represented by the following general formula (b-2) having a base value of 70 mgKOH / g or less.

[0088] [Chemical formula 2]

[0089]

[0090] In the above general formula (b-2), R is independently a hydrocarbon group having 8 to 30 carbon atoms.

[0091] Examples of the hydrocarbon group that can be selected as R include alkyl groups having 8 to 30 carbon atoms.

[0092] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition having good emulsification resistance, the content of the neutral calcium sulfonate (B2) is 8.0% by mass or less, 6.0% by mass or less, 5.0% by mass or less, 4.0% by mass or less, or 3.5% by mass or less, based on the total amount (100% by mass) of the lubricating oil composition, and may be 0% by mass or more, 0.5% by mass or more, 1.0% by mass or more, or 1.5% by mass or more.

[0093] 《Calcium phenolate (B3)》

[0094] The lubricating oil composition according to one embodiment of the present invention may contain calcium phenate (B3) as the calcium-based detergent (B).

[0095] The ratio of the content (b3) of the calcium phenate (B3) in terms of calcium atoms to the content (b) of the calcium-based detergent (B) in terms of calcium atoms [(b3) / (b)] is preferably 0 to 0.02.

[0096] In the case of a lubricating oil composition having the ratio [(b3) / (b)] of more than 0.02, a decrease in emulsification resistance is observed, and there is a concern that viscosity increase may occur due to mixing of water.

[0097] As the calcium phenate (B3) used in one embodiment of the present invention, a highly basic calcium phenate (B31) having a base value of 100 mgKOH / g or more can be mentioned.

[0098] The base value of the highly basic calcium phenate (B31) used in one embodiment of the present invention can be 120 mgKOH / g or more, 150 mgKOH / g or more, 170 mgKOH / g or more, or 200 mgKOH / g or more, and can be 400 mgKOH / g or less, or 350 mgKOH / g or less.

[0099] Examples of the calcium phenate (B3) used in one embodiment of the present invention include compounds represented by the following general formula (b-3).

[0100] [Chemical formula 3]

[0101]

[0102] In the above general formula (b-3), R is independently a hydrocarbon group having 8 to 30 carbon atoms, and y is an integer of 0 or more.

[0103] Examples of the hydrocarbon group that can be selected as R include alkyl groups having 8 to 30 carbon atoms.

[0104] 《Overbased calcium sulfonate (B4)》

[0105] The lubricating oil composition of one embodiment of the present invention may contain a high-based calcium sulfonate (B4) having a base value of 120 mgKOH / g or more, within a range not impairing the effects of the present invention.

[0106] The base value of the overbased calcium sulfonate (B4) can be 120 mgKOH / g or more, 150 mgKOH / g or more, 170 mgKOH / g or more, or 200 mgKOH / g or more, and can be 500 mgKOH / g or less, 400 mgKOH / g or less, or 350 mgKOH / g or less.

[0107] However, from the viewpoint of obtaining a lubricating oil composition having good emulsification resistance, the content of such other metal compounds is preferably as small as possible.

[0108] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of obtaining a lubricating oil composition having good emulsification resistance, the ratio of the content (b4) of the overbased calcium sulfonate (B4) in terms of calcium atom relative to the content (b) of the calcium-based detergent (B) in terms of calcium atom [(b4) / (b)] is preferably less than 0.10.

[0109] <Component (C): Viscosity index improver>

[0110] The lubricating oil composition of one embodiment of the present invention may further contain a viscosity index improver (C). By containing a viscosity index improver, a lubricating oil composition having excellent fuel efficiency can be obtained.

[0111] In addition, the viscosity index improver (C) used in one embodiment of the present invention may be used alone or in combination of two or more.

[0112] Examples of the viscosity index improver (C) used in one embodiment of the present invention include polymers such as non-dispersed polymethacrylate, dispersed polymethacrylate, olefin copolymers (e.g., ethylene-propylene copolymers, etc.), dispersed olefin copolymers, and styrene copolymers (e.g., styrene-diene copolymers, styrene-isoprene copolymers, etc.).

[0113] The viscosity index improver (C) used in one embodiment of the present invention may be a comb polymer having a structure having a plurality of trifurcated branch points from which high molecular weight side chains branch on the main chain, or a star polymer having a structure in which three or more chain polymers are bonded to one atom such as a carbon atom.

[0114] In the lubricating oil composition of one embodiment of the present invention, from the viewpoint of providing a lubricating oil composition capable of suppressing the amount of coking generated, the content of the viscosity index improver (C) in terms of resin component is preferably 0.40% by mass or less, more preferably 0.35% by mass or less, and even more preferably 0.30% by mass or less, based on the total amount (100% by mass) of the lubricating oil composition. It may also be 0.01% by mass or more, 0.02% by mass or more, 0.03% by mass or more, 0.04% by mass or more, or 0.05% by mass or more.

[0115] In addition, the viscosity index improver (C) or the pour point depressant and defoaming agent described later used in one embodiment of the present invention are usually commercially available in the form of a solution dissolved in a diluent oil such as mineral oil or synthetic oil in consideration of the handling properties and solubility in the base oil (A). However, the content of the viscosity index improver (C) is the content calculated as the resin component (solid content) excluding the diluent oil.

[0116] <Lubricant Additives>

[0117] The lubricating oil composition of one embodiment of the present invention may further contain other lubricating oil additives other than components (B) to (C) as necessary, within a range not impairing the effects of the present invention.

[0118] Examples of such lubricating oil additives include metallic detergents other than component (B), pour point depressants, antioxidants, friction modifiers, anti-wear agents, metal deactivators, ashless dispersants, metal deactivators, and defoaming agents.

[0119] These lubricating oil additives may be used alone or in combination of two or more.

[0120] [Metallic detergent]

[0121] The lubricating oil composition of one embodiment of the present invention may or may not further contain a metallic detergent other than the component (B).

[0122] The metal-based detergents may be used alone or in combination of two or more.

[0123] As the metal-based detergent used in one embodiment of the present invention, metal salts such as metal sulfonates, metal salicylates and metal phenates can be cited. In addition, as the metal atom constituting the metal salt, a metal atom selected from alkali metals and alkaline earth metals (excluding Ca) can be cited.

[0124] More specifically, sodium or magnesium can be mentioned.

[0125] In addition, the metal-based detergent used in one embodiment of the present invention may be a neutral metal-based detergent or a highly basic metal-based detergent.

[0126] In addition, when the lubricating oil composition of one embodiment of the present invention contains the component (B), a metallic detergent other than the component (B) may not be contained.

[0127] When the lubricating oil composition of one embodiment of the present invention contains component (B), the content of the metallic detergent other than component (B) can be less than 50 parts by mass, less than 20 parts by mass, less than 10 parts by mass, less than 5.0 parts by mass, less than 2.0 parts by mass, less than 1.0 parts by mass, less than 0.10 parts by mass, less than 0.01 parts by mass, or less than 0.001 parts by mass relative to 100 parts by mass of the total amount of component (B) contained in the lubricating oil composition.

[0128] [Pour point depressant]

[0129] The lubricating oil composition of one embodiment of the present invention may further contain a pour point depressant. The pour point depressants may be used alone or in combination of two or more.

[0130] Examples of the pour point depressant used in one embodiment of the present invention include polymethacrylates, alkylated aromatic compounds, copolymers of fumarate esters and vinyl acetate, and copolymers of ethylene and vinyl acetate. Polymethacrylates having a weight average molecular weight of 40,000 to 200,000 are preferred.

[0131] [Antioxidant]

[0132] The lubricating oil composition of one embodiment of the present invention may further contain an antioxidant. The antioxidant may be used alone or in combination of two or more.

[0133] As the antioxidant used in one embodiment of the present invention, there can be mentioned, for example, amine antioxidants such as alkylated diphenylamine, phenylnaphthylamine, and alkylated phenylnaphthylamine; phenolic antioxidants such as 2,6-di-tert-butylphenol, 4,4'-methylenebis(2,6-di-tert-butylphenol), 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate; sulfur antioxidants such as phenothiazine, di(octadecyl) sulfide, 3,3'-dilauryl thiodipropionate, and 2-mercaptobenzimidazole.

[0134] [Friction modifiers and anti-wear agents]

[0135] The lubricating oil composition of one embodiment of the present invention may further contain a friction modifier or an anti-wear agent. The friction modifier or the anti-wear agent may be used alone or in combination of two or more.

[0136] As friction modifiers and anti-wear agents used in one embodiment of the present invention, for example, as friction modifiers and anti-wear agents, there can be cited sulfur compounds such as sulfided olefins, dialkyl polysulfides, diaryl alkyl polysulfides, and diaryl polysulfides; phosphorus compounds such as phosphates, thiophosphates, phosphites, alkyl hydrogen phosphites, phosphate amine salts, and phosphite amine salts; organic molybdenum compounds such as molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and amine salts of molybdic acid; organic zinc compounds such as zinc dithiophosphate (ZnDTP) and zinc dithiocarbamate (ZnDTC); ashless friction modifiers such as amine compounds, fatty acid esters, fatty amides, fatty acids, aliphatic alcohols, aliphatic ethers, urea compounds, and hydrazide compounds, etc.

[0137] [Metal passivator]

[0138] The lubricating oil composition of one embodiment of the present invention may further contain a metal deactivator. The metal deactivators may be used alone or in combination of two or more.

[0139] Examples of the metal deactivator used in one embodiment of the present invention include benzotriazole, triazole derivatives, benzotriazole derivatives, and thiadiazole derivatives.

[0140] [Ashless dispersant]

[0141] The lubricating oil composition of one embodiment of the present invention may further contain an ashless dispersant from the viewpoint of improving dispersibility. The ashless dispersant may be used alone or in combination of two or more.

[0142] As the ashless dispersant used in one embodiment of the present invention, alkenyl succinimide is preferred, and examples thereof include bis(alkenyl succinimide) represented by the following general formula (f-1) and mono(alkenyl succinimide) represented by the following general formula (f-2).

[0143] [Chemical formula 4]

[0144]

[0145] In the above general formulas (f-1) and (f-2), R f1 , R f2 and R f3 Each independently is an alkenyl group having a number average molecular weight (Mn) of 900 to 2500.

[0146] As available as R f1 , R f2 and R f3 Examples of the alkenyl group that can be selected include a polybutenyl group and a polyisobutenyl group.

[0147] A f1 , A f2 and A f3 Each independently represents an alkylene group having 2 to 5 carbon atoms.

[0148] x1 is an integer from 2 to 6.

[0149] x2 is an integer from 2 to 6.

[0150] It should be noted that the compound represented by the aforementioned general formula (f-1) or (f-2) may also be a modified alkenyl succinimide obtained by reacting with one or more selected from boron compounds, alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, epoxy compounds and organic acids.

[0151] [Defoaming agent]

[0152] The lubricating oil composition of one embodiment of the present invention may further contain a defoaming agent. The defoaming agent may be used alone or in combination of two or more.

[0153] Examples of the defoaming agent used in one embodiment of the present invention include alkyl silicone-based defoaming agents, fluorosilicone-based defoaming agents, and fluoroalkyl ether-based defoaming agents.

[0154] [Properties of Lubricating Oil Composition]

[0155] The kinematic viscosity of the lubricating oil composition of one embodiment of the present invention at 40° C. is preferably 10 to 150 mm 2 / s, more preferably 20 to 120 mm 2 / s, more preferably 30 to 110 mm 2 / s, more preferably 40 to 100 mm 2 / s, more preferably 50 to 90 mm 2 / s, particularly preferably 55 to 85 mm 2 / s.

[0156] The kinematic viscosity of the lubricating oil composition of one embodiment of the present invention at 100° C. is preferably 9.5 mm 2 / s or more, and the upper limit is not particularly limited, for example, it can be less than 16.3mm 2 / s.

[0157] The viscosity index of the lubricating oil composition according to one embodiment of the present invention is preferably 80 or more, more preferably 100 or more, more preferably 110 or more, further preferably 120 or more, and further preferably 130 or more.

[0158] The lubricating oil composition of one embodiment of the present invention has an atomization rate measured and calculated by the method described in the Examples described below, preferably 0.90 mass % or less, more preferably 0.80 mass % or less, further preferably 0.70 mass % or less, further preferably 0.65 mass % or less, and particularly preferably 0.60 mass % or less.

[0159] For the lubricating oil composition of one embodiment of the present invention, when a panel coking test is carried out for 24 hours at an oil temperature of 90°C and a panel temperature of 300°C according to Fed. Test Method Std. 791-3462 based on the method described in the examples, the amount of coked products attached to the panel is preferably 150 mg or less, more preferably 110 mg or less, further preferably 100 mg or less, and particularly preferably 80 mg or less.

[0160] The base number (perchloric acid method) of the lubricating oil composition of one embodiment of the present invention can be 5.0 mgKOH / g or more, 7.0 mgKOH / g or more, 9.0 mgKOH / g or more, or 9.2 mgKOH / g or more, and can be 15.0 mgKOH / g or less, 12.0 mgKOH / g or less, or 10.0 mgKOH / g or less.

[0161] The lubricating oil composition of one embodiment of the present invention is used as a sample, and according to the test method of ASTM D 2619 "Standard Test Method for Hydrolytic Stability of Hydraulic Fluids (Beverage Bottle Method)", a copper catalyst and 25 mL of distilled water are placed in a container containing 75 mL of the sample, and the measurement is performed by the operation of the Examples described below. The volume ratio of the emulsion layer obtained by the measurement is preferably 30 volume % or less, more preferably 28 volume % or less, and even more preferably 26 volume % or less.

[0162] [Use of lubricating oil composition]

[0163] The lubricating oil composition according to one embodiment of the present invention is excellent in anti-fogging properties in a high-temperature environment and has a high effect of suppressing coking.

[0164] Therefore, the lubricating oil composition of one embodiment of the present invention can be applied to various devices that can exert the above-mentioned characteristics, and can be suitable for lubrication between various parts in an internal combustion engine. Moreover, in an internal combustion engine, it can be more suitable for lubrication between various parts in an internal combustion engine (hydrogen fuel engine) equipped with a turbocharger and running with hydrogen as fuel. Since the fuel of a hydrogen fuel engine with a turbocharger is hydrogen, the temperature in the combustion chamber becomes very high, and the lubricating oil composition is easily atomized in an environment. The atomized lubricating oil composition is discharged to the turbine impeller of the turbocharger arranged on the exhaust passage side, and adheres to the turbine impeller and becomes the main cause of coking. In contrast, the lubricating oil composition of one embodiment of the present invention has excellent fog resistance in a high temperature environment, so even if it is used in a hydrogen fuel engine equipped with a turbocharger, the amount of the lubricating oil composition adhering to the turbine impeller can be suppressed, and the occurrence of coking can be effectively suppressed.

[0165] In addition, the lubricating oil composition of another embodiment of the present invention has the above-mentioned characteristics and is also excellent in emulsification resistance. Therefore, the lubricating oil composition can prevent the viscosity increase of the lubricating oil composition caused by the mixing of water, and prevent the failure of the equipment used. The lubricating oil composition of this embodiment can be applied to various devices that can exert the above-mentioned characteristics, and can be more suitable for lubrication between various parts in an internal combustion engine (hydrogen fuel engine) that runs with hydrogen as fuel. Since hydrogen fuel engines use hydrogen as fuel, water is easily mixed into the lubricating oil composition. Sometimes the lubricating oil composition is emulsified due to the mixing of water. The hydrogen fuel engine needs to discharge the generated water to the outside of the vehicle, but if it is emulsified, it becomes difficult to discharge. In addition, due to emulsification, the viscosity increase of the lubricating oil composition is caused, which also becomes a cause of engine equipment failure. In contrast, the lubricating oil composition of one embodiment of the present invention exhibits excellent emulsification resistance, can suppress the viscosity increase caused by the mixing of water, and thus can prevent the failure of the hydrogen fuel engine before it happens. For the lubricating oil composition of this embodiment, even in a hydrogen fuel engine, it can be suitable for lubrication of a hydrogen fuel engine with a turbocharger.

[0166] Furthermore, in consideration of the above-mentioned characteristics of the lubricating oil composition of one embodiment of the present invention, the present invention can also provide the following [I].

[0167] [I] A method for lubricating an internal combustion engine, comprising applying the lubricating oil composition according to one embodiment of the present invention to the lubrication of the internal combustion engine.

[0168] As the internal combustion engine described in [I] above, for example, a hydrogen fuel engine can be cited, and more specifically, a hydrogen fuel engine equipped with a turbocharger can be cited. In particular, in a hydrogen fuel engine equipped with a turbine impeller of a turbocharger provided on the exhaust passage side, the occurrence of coking can be effectively suppressed. Furthermore, in another embodiment of the present invention, equipment failure caused by mixing water into a lubricating oil composition can be prevented before it occurs.

[0169] As described above, the present invention discloses the following aspects.

[0170] [1] A lubricating oil composition comprising a base oil (A) having a NOACK value of 6% by mass or less, wherein the NOACK value is a value measured by a NOACK test conducted at 250° C. for 1 hour in accordance with ASTM D5800,

[0171] The lubricating oil composition has a CCS viscosity at -25°C of 7000 mPa·s or less,

[0172] The lubricating oil composition has a HTHS viscosity at 150° C. of 2.9 mPa·s or more.

[0173] [2] A lubricating oil composition comprising: a base oil (A) having a NOACK value of 6% by mass or less, the NOACK value being a value measured by a NOACK test conducted at 250° C. for 1 hour in accordance with ASTM D5800, and

[0174] A calcium detergent (B), the calcium detergent (B) comprising at least calcium salicylate (B1), and optionally comprising at least one selected from a neutral calcium sulfonate (B2) having a base value of 70 mgKOH / g or less and a calcium phenate (B3),

[0175] The ratio of the content (b2) of the neutral calcium sulfonate (B2) in terms of calcium atoms to the content (b) of the calcium-based detergent (B) in terms of calcium atoms [(b2) / (b)] is 0 to 0.40,

[0176] The ratio of the content (b3) of the calcium phenate (B3) in terms of calcium atoms to the content (b) of the calcium-based detergent (B) in terms of calcium atoms [(b3) / (b)] is 0 to 0.02,

[0177] The lubricating oil composition has a CCS viscosity at -25°C of 7000 mPa·s or less,

[0178] The lubricating oil composition has a HTHS viscosity at 150° C. of 2.9 mPa·s or more

[0179] The lubricating oil composition is used in an internal combustion engine which operates with hydrogen as fuel.

[0180] [3] The lubricating oil composition according to [1] or [2], further comprising a viscosity index improver (C),

[0181] The content of the viscosity index improver (C) as converted to a resin component is 0.40% by mass or less based on the total amount of the lubricating oil composition.

[0182] [4] The lubricating oil composition according to any one of [1] to [3] above, which is used for an internal combustion engine having a turbocharger and operating with hydrogen as fuel.

[0183] [5] A method for lubricating an internal combustion engine, comprising using the lubricating oil composition according to any one of [1] to [4] above for lubricating the internal combustion engine.

[0184] [6] The internal combustion engine lubrication method according to [5] above, wherein the internal combustion engine is an internal combustion engine having a turbocharger and operating with hydrogen as fuel.

[0185] Example

[0186] Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. It should be noted that the methods for measuring various physical properties are as follows.

[0187] (1) Kinematic viscosity

[0188] The measurement was carried out according to ASTM D445.

[0189] (2) Viscosity index at 40°C and 100°C

[0190] Calculated according to ASTM D2270.

[0191] (3)NOACK value

[0192] The measurement was performed according to ASTM D5800 at 250°C for 1 hour.

[0193] (4) CCS viscosity (-25℃)

[0194] According to ASTM D5293, measured at -25°C.

[0195] (5) HTHS viscosity (150℃)

[0196] Measured according to ASTM D4683 at 150°C.

[0197] (6) Calcium atom (Ca) content

[0198] The measurement was carried out according to ASTM D5185.

[0199] (7) Alkalinity (perchloric acid method)

[0200] Measured by the perchloric acid method according to ASTM D2896.

[0201] Examples 1a to 6a, Comparative Examples 1a to 2a

[0202] The base oils and various additives used in the following Examples 1a to 6a and Comparative Examples 1a to 2a are as follows.

[0203] <Base oil (A)>

[0204] Table 1 shows the API (American Petroleum Institute) base oil classification and properties of the base oils (a1-1) to (a1-5) and base oils (a2-1) to (a2-5) used in Examples and Comparative Examples.

[0205] [Table 1]

[0206] Table 1

[0207]

[0208] <Various additives>

[0209] Viscosity index improver (1): a solution obtained by diluting a hydrogenated styrene-diene copolymer with a diluent oil classified as Group III of API base oil category, resin component concentration = 6.5% by mass.

[0210] Viscosity index improver (2): a solution obtained by diluting a hydrogenated styrene-diene copolymer with a diluent oil classified as Group I of API base oil category, resin component concentration = 10.7% by mass.

[0211] Pour point depressant: polymethacrylate (VISCOPLEX 1-500 (manufactured by EVONIK))

[0212] Additive blend: JASO DH-2 additive package containing antioxidants, metallic detergents, dispersants, anti-wear agents and defoamers.

[0213] The above base oils and various additives were added in the amounts shown in Table 2 and mixed thoroughly to prepare lubricating oil compositions. Table 2 shows the properties of the base oils (mixed base oils) used and the properties of the prepared lubricating oil compositions.

[0214] The following tests were carried out using the prepared lubricating oil composition. The results are also shown in Table 2.

[0215] (1) Fog resistance test

[0216] Under the following measurement conditions, each sample oil as the prepared lubricating oil composition was mixed with compressed air and atomized, and the amount of oil after floating atomization (atomized mass, unit: g) was measured.

[0217] (Measurement conditions)

[0218] Test device: TACO haze measuring device (model: C3-0807)

[0219] Air pressure: 0.2MPa

[0220] Sample oil volume: 40g

[0221] Then, the fogging rate was measured by the following formula (i).

[0222] Formula (i): Atomization rate (mass %) = [atomization mass (g) / mass of sample oil (=40 g)] × 100

[0223] The lower the mist rate, the less floating mist, the better the anti-fogging property, and the lubricating oil composition can be said to have suppressed coking. In this example, when the mist rate is 0.90 mass % or less, it is judged to be a lubricating oil composition with good anti-fogging property.

[0224] (2) Panel coking test

[0225] The measurement was carried out according to Fed. Test Method Std. 791-3462.

[0226] Specifically, 300 mL of sample oil was placed in a test container with a splasher, an aluminum panel was installed on top, the sample oil was heated to 90°C, the panel was heated to 300°C, the splasher was rotated, and the oil was continuously splashed on the panel. The test was carried out for 24 hours. After the test, the amount of coke attached to the panel was weighed (unit: mg).

[0227] The smaller the amount of adhesion, the better the coking resistance of the lubricating oil composition. In this example, when the amount of adhesion is 150 mg or less, it is judged to be a lubricating oil composition with good coking resistance.

[0228] [Table 2]

[0229]

[0230] According to Table 2, the following results were obtained: the lubricating oil compositions prepared in Examples 1a to 6a were superior in anti-fogging properties and effectively suppressed the occurrence of coking, compared with the lubricating oil compositions of Comparative Examples 1a to 2a.

[0231] Examples 1b to 8b, Reference Examples 1b to 8b

[0232] The components shown in Table 3 or Table 4 were added in the same amounts and mixed thoroughly to prepare lubricating oil compositions. The base oils and various additives used in Examples and Comparative Examples are shown below.

[0233] <Base oil>

[0234] "Base oil": mineral oil classified as Group III of API base oil category, kinematic viscosity at 40°C = 41.58 mm 2 / s, 100℃ kinematic viscosity = 7.307mm 2 / s, viscosity index = 141, NOACK value = 2.9 mass %.

[0235] <Various additives>

[0236] "Overbased salicylic acid Ca (1)": calcium salicylate having a base value (perchloric acid method) of 170 mgKOH / g, and a Ca content of 6.1% by mass.

[0237] "Overbased salicylic acid Ca (2)": calcium salicylate having a base value (perchloric acid method) of 225 mgKOH / g, and a Ca content of 8.0% by mass.

[0238] "Overbased salicylic acid Ca (3)": calcium salicylate having a base value (perchloric acid method) of 350 mgKOH / g, and a Ca content of 12.1% by mass.

[0239] "Neutral salicylic acid Ca": calcium salicylate having a base value (perchloric acid method) of 64 mgKOH / g, and a Ca content of 2.3% by mass.

[0240] "Overbased sulfonic acid Ca (1)": calcium sulfonate having a base value (perchloric acid method) of 307 mgKOH / g, and a Ca content of 11.9% by mass.

[0241] "Overbased sulfonic acid Ca (2)": calcium sulfonate having a base value (perchloric acid method) of 300 mgKOH / g, and a Ca content of 11.6% by mass.

[0242] "Overbased Ca sulfonic acid (3)": calcium sulfonate having a base value (perchloric acid method) of 425 mgKOH / g, and a Ca content of 16.0% by mass.

[0243] "Neutral Ca sulfonic acid": calcium sulfonate having a base value (perchloric acid method) of 19 mgKOH / g, and a Ca content of 2.4% by mass.

[0244] "Highly basic phenol Ca": calcium phenol having a base value (perchloric acid method) of 250 mgKOH / g and a Ca content of 9.3% by mass.

[0245] "Viscosity index improver": a solution obtained by diluting a hydrogenated styrene-diene copolymer with a diluent oil classified as Group I of API base oil category, resin component concentration = 10.7% by mass.

[0246] "Pour point depressant": polymethacrylate (VISCOPLEX 1-500 (manufactured by EVONIK))

[0247] Additive blend: JASO DH-2 additive package containing antioxidants, ashless dispersants, anti-wear agents and defoamers.

[0248] The prepared lubricating oil composition was subjected to the following hydrolysis stability test. The results of the test are shown in Tables 3 and 4.

[0249] [Hydrolysis stability test]

[0250] The lubricating oil composition thus prepared was used as a sample. According to the test method of ASTM D 2619 "Standard Test Method for Hydrolytic Stability of Hydraulic Fluids (Beverage Bottle Method)", a copper catalyst and 25 mL of distilled water were placed in a container containing 75 mL of the sample, and the temperature was raised to 93° C., and the container was kept for 48 hours while rotating. Then, the mixture was cooled to room temperature (25° C.), and the liquid in the container was transferred to a measuring cylinder and allowed to stand for 24 hours. The total amount of the oil layer, water layer, and emulsion layer after standing was set to 100% by volume, and the volume ratio of each layer was measured.

[0251] The smaller the volume ratio of the emulsion layer, the better the emulsification resistance of the lubricating oil composition. In this example, if the volume ratio of the emulsion layer is 30 volume % or less, it is judged that the lubricating oil composition has good emulsification resistance.

[0252] [Table 3]

[0253]

[0254] [Table 4]

[0255]

[0256] According to Table 1, the following results were obtained: the lubricating oil compositions prepared in Examples 1b to 8b had a low volume ratio of the emulsion layer in the hydrolysis stability test and were excellent in emulsification resistance.

Claims

1. A lubricating oil composition comprising a base oil (A) having a NOACK value of 6% by mass or less, wherein the NOACK value is a value measured by a NOACK test conducted at 250° C. for 1 hour in accordance with ASTM D5800, The lubricating oil composition has a CCS viscosity at -25°C of 7000 mPa·s or less, The lubricating oil composition has a HTHS viscosity at 150° C. of 2.9 mPa·s or more.

2. The lubricating oil composition according to claim 1, wherein The invention further comprises a calcium detergent (B), wherein the calcium detergent (B) comprises at least calcium salicylate (B1) and may optionally comprise at least one selected from a neutral calcium sulfonate (B2) having a base value of 70 mgKOH / g or less and a calcium phenate (B3), The ratio of the content (b2) of the neutral calcium sulfonate (B2) in terms of calcium atoms to the content (b) of the calcium-based detergent (B) in terms of calcium atoms [(b2) / (b)] is 0 to 0.40, The ratio of the content (b3) of the calcium phenate (B3) in terms of calcium atoms to the content (b) of the calcium-based detergent (B) in terms of calcium atoms [(b3) / (b)] is 0 to 0.02, The lubricating oil composition is used in an internal combustion engine which operates with hydrogen as fuel.

3. The lubricating oil composition according to claim 1 or 2, wherein further containing a viscosity index improver (C), The content of the viscosity index improver (C) as converted to a resin component is 0.40% by mass or less based on the total amount of the lubricating oil composition. 4 . The lubricating oil composition according to claim 1 , which is used for an internal combustion engine having a turbocharger and operating with hydrogen as fuel.

5. A method for lubricating an internal combustion engine, wherein: The lubricating oil composition according to any one of claims 1 to 4 is used for lubrication of an internal combustion engine.

6. The internal combustion engine lubrication method according to claim 5, wherein: The internal combustion engine is an internal combustion engine that has a turbocharger and operates using hydrogen as fuel.

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