Lubricant composition for internal combustion engines

Abstract

To provide a lubricant composition for an internal combustion engine in which both an amount of evaporation and viscosity of the lubricant composition in a low-temperature environment are reduced.SOLUTION: A lubricant composition for an internal combustion engine comprises a base oil that satisfies a relational formula (1): Y≥15.3X+348, where X is kinematic viscosity at 100°C and Y is a distillation temperature T20 at a distillation rate of 20 volume% in a distillation curve.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This disclosure relates to lubricating oil compositions for internal combustion engines. [Background technology]

[0002] In recent years, in response to environmental issues such as global warming, automobile engines are required to both reduce CO2 emissions and comply with exhaust gas regulations. Therefore, the latest automobile engines require technologies such as miniaturization and fuel efficiency. Furthermore, to comply with exhaust gas regulations, automobile engines employ filters (diesel particulate filters; also known as DPFs) to capture particulate matter in the exhaust.

[0003] In lubricating oil compositions for internal combustion engines (hereinafter sometimes simply referred to as "lubricating oil compositions") used to lubricate the engine, it is required to reduce the amount of evaporation of the lubricating oil composition. If the amount of evaporation of the lubricating oil composition is high, the heat load per unit of oil volume tends to increase relatively, and the evaporated substances of the lubricating oil composition tend to cause clogging of the DPF, which leads to a decrease in DPF performance and a shortening of the replacement frequency. Furthermore, from the viewpoint of fuel efficiency, it is preferable to reduce the amount of evaporation of the lubricating oil composition.

[0004] For example, Patent Document 1 discloses a fuel-efficient engine lubricant composition containing a molybdenum-based friction modifier, further comprising a friction modifier having an ester bond. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2001-19990 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, attempting to reduce the evaporation rate of the lubricating oil composition increases its viscosity at low temperatures (e.g., -30°C) (hereinafter also referred to as "low-temperature viscosity"), and there is a trade-off between the two. High low-temperature viscosity not only reduces the starting performance of the engine in low-temperature environments, but also tends to worsen fuel efficiency. Thus, there is a desire for a lubricating oil composition that reduces both the evaporation rate (more specifically, the NOACK evaporation rate) and the viscosity in low-temperature environments (more specifically, the mini-rotary viscosity at -30°C). Although such a lubricating oil composition is considered to be an effective means of improving fuel efficiency in internal combustion engines, it has not yet been made available.

[0007] This invention was made under such circumstances, and the problem that one embodiment of this invention aims to solve is to provide a lubricating oil composition for an internal combustion engine in which both the evaporation rate of the lubricating oil composition and the viscosity in a low-temperature environment are reduced. [Means for solving the problem]

[0008] The engine oil compositions of this disclosure include the following embodiments. <1> A lubricating oil composition for internal combustion engines, containing a base oil that satisfies the following relationship (1), where X is the kinematic viscosity at 100°C and Y is the distillation temperature T20 at a distillation volume of 20% by volume in the distillation curve. Relation (1): Y ≥ 15.3X + 348 <2> The base oil has a kinematic viscosity of 30 mm at 100°C. 2 The above is less than or equal to / s. <1> The lubricating oil composition for internal combustion engines described above. <3> The base oil is such that the distillation temperature T20 at a distillation volume of 20 volume% in the distillation curve is 400°C or higher. <1> or <2> The lubricating oil composition for internal combustion engines described above. <4> The base oil comprises at least one of a plant-derived base oil and a chemically synthesized base oil. <1> ~ <3> A lubricating oil composition for internal combustion engines as described in any one of the following. <5> In accordance with ASTM D 5800-19, the NOACK evaporation rate measured at 250°C for 1 hour is 14% by mass or less. <1> ~ <4> A lubricating oil composition for internal combustion engines as described in any one of the following. <6> The base oil has a sulfur content of 0.01% by mass or less relative to the total mass of the base oil. <1> ~ <5> A lubricating oil composition for internal combustion engines as described in any one of the following. <7> The base oil is such that, in a chromatogram obtained by gel permeation chromatography of the tetrahydrofuran-soluble components, with the vertical axis representing the detected amount and the horizontal axis representing the elution time (minutes), the full width at half maximum of the maximum peak is 0.9 or less. <1> ~ <6> A lubricating oil composition for internal combustion engines as described in any one of the following. [Effects of the Invention]

[0009] According to one embodiment of the present invention, it is possible to provide a lubricating oil composition for an internal combustion engine in which both the evaporation rate of the lubricating oil composition and the viscosity in a low-temperature environment are reduced. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram shows the correlation between the kinematic viscosity at 100°C and the distillation temperature T20 at a distillation volume of 20% in the distillation curve for the base oil used in each example. [Modes for carrying out the invention]

[0011] The lubricating oil compositions for internal combustion engines relating to this disclosure will be described in detail below. The following description may be based on representative embodiments, but the lubricating oil compositions for internal combustion engines relating to this disclosure are not limited to such embodiments.

[0012] In this disclosure, a numerical range indicated using "~" means a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions. Also, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. In the present disclosure, the amount of each component in the composition means the total amount of the corresponding plurality of substances present in the composition when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified. In the present disclosure, "mass%" and "weight%" are synonymous. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In the present disclosure, "JIS" is used as an abbreviation for Japanese Industrial Standards.

[0013] <Lubricating oil composition for internal combustion engines> The lubricating oil composition for internal combustion engines according to the present disclosure is a lubricating oil composition for internal combustion engines containing a base oil that satisfies the relationship of the following relational expression (1) when the kinematic viscosity at 100 °C is X and the distillation temperature T20 at a distillation amount of 20% by volume in the distillation curve is Y.

[0014] Relational expression (1): Y ≧ 15.3X + 348

[0015] In the lubricating oil composition for internal combustion engines according to the present disclosure, both the evaporation amount of the lubricating oil composition and the viscosity at a low temperature environment (for example, -30 °C) are reduced. Although the mechanism of action by which the lubricating oil composition for internal combustion engines according to the present disclosure exhibits the above effects is not necessarily clear, it is presumed that by containing a base oil in which the relationship between the kinematic viscosity at 100 °C and the distillation temperature T20 at a distillation amount of 20% by volume in the distillation curve is within a predetermined range, the starting performance of the engine part in a low temperature environment is ensured, and the proportion of low molecular weight components that are easily evaporated is kept small.

[0016] (Base oil) The base oil contains a base oil that satisfies the following relationship (1), where X is the kinematic viscosity at 100°C and Y is the distillation temperature T20 at a distillation volume of 20% by volume in the distillation curve. The base oil may also contain base oil that does not satisfy the following relationship (1), within the range in which the effects of this disclosure are achieved. Relation (1): Y ≥ 15.3X + 348

[0017] When the kinematic viscosity of the base oil at 100°C is X and the distillation temperature T20 at a distillation volume of 20% in the distillation curve is Y, it is preferable that the base oil satisfies the relationship in equation (1) below, and more preferably satisfies the relationship in equation (2) below, from the viewpoint of further reducing both the evaporation rate of the lubricating oil composition and the viscosity in low-temperature environments, and more preferably satisfies the relationship in equation (3) below.

[0018] Relation (1): Y ≥ 15.3X + 348 Relational equation (2): Y ≥ 15.3X + 354 Relational equation (3): Y ≥ 15.3X + 360

[0019] There are no particular limitations on the method for producing a lubricating oil composition that satisfies the above relational equations (1) to (3). Examples include: a method of blending at least one of a plant-derived base oil and a chemically synthesized oil; a method of blending two or more base oils with different viscosities; a method of blending a mineral oil base oil from which low-boiling fractions have been removed in advance by distillation; a method of preparing it with additives such as viscosity modifiers; and so on.

[0020] From the perspective of further reducing viscosity in low-temperature environments, the base oil has a kinematic viscosity of 30 mm at 100°C. 2 It is preferable that the speed be less than or equal to 2 mm 2 / s or more 20mm 2 It is more preferable that it be less than or equal to / s, and 2 mm 2 / s or more 15mm 2 It is even more preferable that the kinematic viscosity of the base oil be less than or equal to / s. Furthermore, if the catalog value for the kinematic viscosity of the base oil is available, the catalog value should be used.

[0021] The kinematic viscosity at 100°C mentioned above is a value measured according to the method compliant with JIS K-2283-2000 (ASTM D445-19).

[0022] The method for controlling the kinematic viscosity at 100°C within the above range is not particularly limited, but for example, Methods include: blending at least one of plant-derived base oils and chemically synthesized oils; blending two or more base oils with different viscosities; blending mineral oil base oils from which low-boiling fractions have been removed by distillation; preparing with additives such as viscosity modifiers; and blending chemically synthesized oils whose viscosity has been adjusted by examining reaction conditions such as the degree of polymerization.

[0023] From the viewpoint of further reducing the evaporation rate of the lubricating oil composition, the base oil is preferably such that the distillation temperature T20 at a distillation volume of 20% in the distillation curve is 400°C or higher, more preferably 410°C to 580°C, and even more preferably 420°C to 560°C.

[0024] The distillation temperature T20 at a distillation volume of 20 vol% in the above distillation curve is a value measured according to the GC distillation test method for petroleum products, ASTM D 2887.

[0025] The method for setting the distillation temperature T20 at a distillation volume of 20% in the above distillation curve to within the above range is not particularly limited, but examples include a method of blending at least one of a plant-derived base oil and a chemically synthesized oil; a method of blending a mineral oil base oil from which low-boiling fractions have been removed in advance by distillation; and so on.

[0026] The base oil preferably has a NOACK evaporation rate of 20% by mass or less, more preferably 18% by mass or less, and even more preferably 10% by mass or less. By keeping the NOACK evaporation rate of the base oil below the above range, the evaporation rate of the lubricating oil composition is further reduced. The lower limit of the NOACK evaporation rate of the base oil is not particularly limited. The lower limit of the NOACK evaporation rate of the base oil can be set as appropriate, taking into account the effects and costs related to this disclosure.

[0027] The NOACK evaporation rate of the base oil refers to the evaporation loss (mass%) of the base oil measured under conditions of 250°C for 1 hour, in accordance with ASTM D 5800-19.

[0028] The method for keeping the NOACK evaporation rate of the above base oil within the above range is not particularly limited, but for example, Methods include blending at least one of a plant-derived base oil and a chemically synthesized oil, or blending a mineral oil base oil from which low-boiling fractions have been removed in advance by distillation; and so on.

[0029] From the viewpoint of further reducing the evaporation rate of the lubricating oil composition, the base oil is preferably such that, in a chromatogram obtained by gel permeation chromatography (GPC) of the tetrahydrofuran-soluble components, with the vertical axis representing the detected amount and the horizontal axis representing the elution time (minutes), the full width at half maximum of the maximum peak is 0.9 or less, more preferably 0.8 or less, and even more preferably 0.3 to 0.7.

[0030] The full width at half maximum (FWHM) of the maximum peak refers to the peak width at half maximum (FWHM) observed in a chromatogram obtained by GPC, where the vertical axis is the detection amount and the horizontal axis is the elution time (minutes). The elution time is defined as the time it takes for the molecular weight to reach 10⁴ when converted to polystyrene equivalent.

[0031] The measurement conditions for gel permeation chromatography (GPC) are as follows: <Condition> Equipment: Shodex GPC-101 (manufactured by Showa Denko Corporation) Columns: Three Shodex GPC LF-804 (manufactured by Showa Denko Corporation) Detector: Differential refractive detector, Mobile phase: THF (tetrahydrofuran) Flow rate: 1ml / min, Sample concentration: approx. 1.0mass% / vol%THF, Injection volume: 100μL

[0032] The method for setting the full width at half maximum of the maximum peak in the above GPC to within the above range is not particularly limited, but examples include a method of blending at least one of a plant-derived base oil and a chemically synthesized oil; a method of blending a mineral oil base oil from which low-boiling fractions have been removed in advance by distillation; and so on.

[0033] Examples of base oils include chemically synthesized oils, plant-derived base oils, and mineral oils. From the viewpoint of making it easier to satisfy the relationships (1) to (3) described above, the base oil preferably contains at least one of a plant-derived base oil and a chemically synthesized base oil, and more preferably contains a plant-derived base oil. The base oil may be used alone or two or more types may be used in combination.

[0034] Examples of synthetic oils include base oils containing isoparaffins, poly-α-olefins, α-olefin oligomers, fatty acid esters (such as dialkyldiesters), polyols, alkylbenzenes, polyglycols, phenyl ethers, saturated or unsaturated polyol esters, polyphenyl ethers, hydrocarbons, etc. Synthetic oils may be used individually or in combination of two or more types.

[0035] A plant-derived base oil refers to a base oil containing oil components extracted from plants (including those modified with stabilizers, etc.). A single plant-derived base oil may be used, or two or more may be used in combination. The plant-derived base oil may contain some or more of the components found in the aforementioned chemically synthesized oils and the later-described mineral oils in the composition of the oil components extracted from the plants. Specifically, for example, the plant-derived base oil may be a base oil containing isoparaffin, α-olefin oligomer, fatty acid esters (such as dialkyldiesters), polyols, alkylbenzenes, polyglycols, phenyl ethers, saturated or unsaturated polyol esters, polyphenyl ethers, hydrocarbons, etc., extracted from plants. Examples of plant-derived base oils include soybean oil, sunflower oil, safflower oil, corn oil, meadowfoam oil, rapeseed oil, castor oil, rice bran oil, olive oil, palm oil, and the like.

[0036] Examples of mineral oils include those obtained by appropriately combining refining methods such as solvent refining, hydrorefining, hydrocracking refining, and hydrodewaxing for the lubricating oil fraction of crude oil. The mineral oil may be a paraffinic mineral oil (i.e., a high viscosity index mineral oil-based lubricating oil base oil) highly refined by subjecting a hydrorefined oil, catalytically isomerized oil, etc. to treatments such as solvent dewaxing or hydrodewaxing. The mineral oil may be used alone or in combination of two or more.

[0037] From the viewpoint of more easily satisfying the relationships of the above-mentioned relational expressions (1) to (3) and further reducing both the evaporation amount and the viscosity at low temperature environments of the lubricating oil composition, the total amount of the plant-derived base oil and the chemically synthesized oil is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 15% by mass or more and 100% by mass or less with respect to the total amount of the base oil. The content of the plant-derived base oil may be 98% by mass or less, 96% by mass or less, or 95% by mass or less with respect to the total amount of the base oil.

[0038] (Properties as a Lubricating Oil Composition for Internal Combustion Engines) From the viewpoints of further reducing the viscosity at low temperature environments and anti-wear performance, the kinematic viscosity at 100 °C of the lubricating oil composition of the present disclosure is preferably 4 mm 2 / s or more and 26 mm 2 / s or less, more preferably 4 mm 2 / s or more and 22 mm 2 / s or less, and still more preferably 4 mm 2 / s or more and 18 mm 2 / s or less.

[0039] The kinematic viscosity at 100 °C is a value measured by a method conforming to JIS K-2283-2000 (ASTM D445-19).

[0040] The method for adjusting the kinematic viscosity of the above lubricating oil composition at 100°C to within the above range is not particularly limited, but examples include: a method of blending at least one of a plant-derived base oil and a chemically synthesized oil; a method of blending two or more base oils with different viscosities; a method of blending a mineral oil base oil from which low-boiling fractions have been removed in advance by distillation; a method of preparing it with additives such as viscosity modifiers; and a method of blending a chemically synthesized oil whose viscosity has been adjusted by examining reaction conditions such as the degree of polymerization.

[0041] The lubricating oil composition for internal combustion engines of this disclosure preferably has a NOACK evaporation rate of 14% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less. By keeping the NOACK evaporation rate of the lubricating oil composition for internal combustion engines below the above range, the evaporation rate of the lubricating oil composition is further reduced. The lower limit of NOACK evaporation is not particularly limited. The lower limit of NOACK evaporation can be set as appropriate, taking into account the effects and costs related to this disclosure.

[0042] NOACK evaporation rate refers to the amount of evaporation loss (mass %) of the base oil, measured in accordance with ASTM D 5800-19.

[0043] The method for setting the NOACK evaporation amount within the above range is not particularly limited, but examples include: a method of using a lubricating oil composition containing a plant-derived base oil; a method of using a lubricating oil composition containing a chemically synthesized base oil such as isoparaffin, saturated polyol ester, or unsaturated polyol ester; and so on.

[0044] From the viewpoint of suppressing poisoning of the DPF catalyst, the sulfur content of the base oil is preferably 0% by mass or 0.03% by mass or less, more preferably 0.02% by mass or less, and even more preferably 0.01% by mass or less, relative to the total mass of the base oil. The sulfur content of the base oil is preferable to be as close to 0% by mass as possible relative to the total amount of the base oil.

[0045] The above sulfur content is a value measured according to the method conforming to JIS K 2541-4 (JPI 5S-38-03).

[0046] The methods for reducing the sulfur content to below the above range are not particularly limited, but examples include: blending a base oil synthesized from raw materials with a low sulfur content (e.g., chemically synthesized oil, GTL gas oil, etc.); blending a base oil derived from raw materials with a low sulfur content (e.g., plant-derived base oil, etc.); and using a base oil with a high sulfur content, such as mineral oil, after removing the sulfur component by hydrodesulfurization beforehand.

[0047] (Other additives) The lubricating oil composition for internal combustion engines according to this disclosure may optionally contain known additives commonly used in lubricants, such as metallic detergent dispersants, ashless detergent dispersants, oiliness agents, anti-wear agents, extreme pressure agents, rust inhibitors, friction modifiers, antioxidants, metal deactivators, defoamers, colorants, viscosity index improvers, and pour point depressants.

[0048] Examples of metallic detergent dispersants include sulfonates, phenates, and salicylates, whose metallic components are calcium or magnesium. These metallic detergent dispersants are particularly suitable for lubricating oil compositions used in environments where the internal temperature is high, and their content relative to the total composition is preferably in the range of 0.1% to 5.0% by mass.

[0049] Examples of ashless dispersants include succinimide-based ashless dispersants, succinamide-based ashless dispersants, or boronated derivatives thereof. Examples of succinimide-based ashless dispersants include polyalkenyl succinimides such as bispolypropenyl succinimide, monopropenyl succinimide, bispolybutenyl succinimide, monobutenyl succinimide, bispolypentenyl succinimide, and monopentenyl succinimide. Examples of succinamide-based ashless dispersants include polyalkenyl succinamides such as polypropenyl succinamide, polybutenyl succinamide, and polypentenyl succinamide.

[0050] Typically, the molecular weight (Mw) of the polyalkenyl group in these ashless dispersants is around 70 to 50,000. Examples of these boronated derivatives include ashless dispersants obtained by reacting polyalkenyl succinic anhydride with boron compounds such as boric acid, boric acid esters, and borates, as well as polyamines.

[0051] Examples of oily agents include oleic acid, stearic acid, higher alcohols, amines, esters, sulfurized oils and fats, acidic phosphate esters, and acidic phosphate esters.

[0052] Examples of anti-wear agents include zinc dialkyldithiophosphate, various phosphate esters, thiophosphate esters, and amine salts of various phosphate esters.

[0053] Examples of extreme pressure additives include hydrocarbon sulfides, sulfurized oils and fats, sulfur, phosphate esters, phosphite esters, chlorinated paraffins, and chlorinated diphenyls.

[0054] Rust inhibitors include carboxylic acids, their amine salts, esters, sulfonates, and boron compounds.

[0055] Examples of friction modifiers include organic molybdenum compounds, polyhydric alcohol partial esters, amines, amides, sulfur esters, phosphate esters, acidic phosphate esters and their amine salts, and diols.

[0056] Examples of antioxidants include amine-based, phenol-based, zirconium-based, and sulfur-based antioxidants.

[0057] Examples of metal deactivators include benzotriazole, thiadiazole, and alkenyl succinate esters.

[0058] Examples of antifoaming agents include silicone compounds such as dimethylpolysiloxane, fluorosilicone compounds, and ester compounds.

[0059] Examples of pour point depressants include polyalkyl methacrylates, chlorinated paraffin-naphthalene condensates, and alkylated polystyrenes.

[0060] Examples of viscosity index improvers include polyalkyl methacrylate-based, polyisobutylene-based, ethylene-propylene copolymer-based, styrene-isoprene copolymer-based, styrene-butadiene hydrogenated copolymer-based, and polyisobutylene-based products. The weight-average molecular weight (Mw) (polystyrene equivalent) of the polymer used as a viscosity index improver is preferably 10,000 to 400,000, and particularly preferably 20,000 to 200,000. The amount of such viscosity index improver added is preferably 0.1% to 10% by mass relative to the total amount of the composition. In this invention, the weight-average molecular weight (Mw) is the standard polystyrene equivalent measured by gel permeation chromatography (GPC) under the following conditions. <Condition> Instrument: Shodex GPC-101 (Showa Denko Corporation), Columns: 3 Shodex GPC LF-804 (Showa Denko Corporation), Detector: Differential refractive detector, Mobile phase: THF (tetrahydrofuran), Flow rate: 1 ml / min, Sample concentration: approx. 1.0 mass% / vol% THF, Injection volume: 100 μL

[0061] <Method for preparing a lubricating oil composition for internal combustion engines> The method for preparing the lubricating oil composition for internal combustion engines according to this disclosure is not particularly limited, and the base oil and the aforementioned additives, which may be added as needed, may be appropriately mixed. The mixing order of each component is not particularly limited. [Examples]

[0062] The lubricating oil compositions for internal combustion engines relating to this disclosure will be described in more detail by reference to examples and comparative examples. However, the lubricating oil compositions for internal combustion engines relating to this disclosure are not limited in any way to the examples shown below.

[0063] <Preparation of base oil and additives> (1) Base oil Six types of mineral oil base oils, two types of chemically synthesized oils, and seven types of plant-derived base oils (referred to as "vegetable oils" in the table) were prepared. For each base oil, the kinematic viscosity at 100°C (referred to as "100°C kinematic viscosity" in the table), the distillation temperature T20 at a distillation volume of 20 vol% in the distillation curve (referred to as "T20" in the table), the sulfur content relative to the total mass of the base oil (referred to as "sulfur content" in the table), and the full width at half maximum of the maximum peak in GPC (referred to as "full width at half maximum" in the table) are shown in Tables 1 and 2.

[0064] (2) Other additives The total amounts of all additives, including viscosity index improvers, anti-wear agents, dispersants, metallic detergents, friction modifiers, phenolic antioxidants, pour point depressants, and silicone-based defoamers, are summarized in Tables 1 and 2.

[0065] <Examples 1-14 and Comparative Examples 1-3> The base oil and other additives shown in the <Base Oil and Additives> section above were mixed in the amounts shown in Tables 1 and 2 to obtain the internal combustion engine lubricant compositions for each example.

[0066] Tables 1 and 2 show the results of measuring the sulfur content relative to the total lubricating oil composition in each example of the internal combustion engine lubricating oil composition using the measurement method described above. In the table, "mass%" refers to the mass percentage based on the total mass of the lubricating oil composition for internal combustion engines. "0" in the composition column of Table 1 indicates that the corresponding component is not included. In the table, under the items "Relationship Formula (1)", "Relationship Formula (2)", and "Relationship Formula (3)", items that satisfy the relationships of relations formulas (1) to (3) mentioned above are indicated as "fulfilled", and items that do not satisfy are indicated as "not fulfilled".

[0067] Each lubricating oil composition for internal combustion engines satisfies the requirements of 10W-30 in all SAE viscosity grades and has a kinematic viscosity value at 100 °C of the oil after the shear test described in ASTM D6278-07, which is a requirement of the JASO DH-2 standard, a domestic diesel engine oil standard, of 9.3 mm 2 / s or more.

[0068] In preparing each example and comparative example, considering the impact on fuel efficiency performance, the blending amount of the viscosity index improver was arranged to be the minimum amount while satisfying the above conditions.

[0069] <Evaluation of NOACK evaporation loss> For each lubricating oil composition for internal combustion engines obtained in each example, the NOACK evaporation loss was measured by the above-described measurement method. The results are shown in Tables 1 to 2. In the tables, those with a NOACK evaporation loss value of 14% by mass or less are considered qualified.

[0070] <Evaluation of low-temperature viscosity> For the lubricating oil composition of each example, the viscosity at -30 °C (mm 2 / s) (referred to as "low-temperature MRV viscosity" in the tables) using a mini rotary viscometer was measured in accordance with ASTM D4684. The results are shown in Tables 1 to 2. In the tables, those with a viscosity value of 16,000 (mm 2 / s) or less are considered qualified.

[0071]

Table 1

[0072]

Table 2

[0073] Figure 1 is a correlation diagram between the kinematic viscosity at 100 °C and the distillation temperature T20 at a distillation volume of 20% by volume in the distillation curve for the base oils used in each example. In the figure, for the plots of each base oil, the applied numerical values adopt the numerical values described in the items of the kinematic viscosity at 100 °C and the T20 described in Table 1.

[0074] As shown in Tables 1 and 2 and Figure 1, the lubricating oil compositions for internal combustion engines of the examples containing a base oil that satisfies relation (1) showed reduced NOACK evaporation and viscosity under low-temperature conditions compared to the lubricating oil compositions for internal combustion engines of the comparative examples that did not contain a base oil that satisfies relation (1).

Claims

1. When the kinematic viscosity at 100°C is X and the distillation temperature T20 at a distillation volume of 20% by volume in the distillation curve is Y, the base oil contains a base oil that satisfies the following relationship (1): A lubricating oil composition for internal combustion engines, wherein the NOACK evaporation rate, measured at 250°C for 1 hour in accordance with ASTM D 5800-19, is 14% by mass or less, The base oil contains a sulfur content of 0.01% by mass or less relative to the total mass of the base oil, and in a chromatogram of tetrahydrofuran-soluble components obtained by gel permeation chromatography, with the vertical axis representing the detected amount and the horizontal axis representing the elution time (minutes), the full width at half maximum of the maximum peak is 0.3 or more and 0.7 or less. The base oil is a lubricating oil composition for internal combustion engines, wherein the distillation temperature T20 at a distillation volume of 20% in the distillation curve is 400°C or higher. Relational equation (1): Y ≥ 15.3X + 348

2. The base oil has a kinematic viscosity of 30 mm at 100°C. ２ The lubricating oil composition for an internal combustion engine according to claim 1, wherein the value is less than or equal to / s.

3. The lubricating oil composition for internal combustion engines according to claim 1 or claim 2, wherein the base oil comprises at least one of a plant-derived base oil and a chemically synthesized base oil.

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