Lubricating oil composition

Abstract

To provide a novel lubricant oil composition capable of exhibiting excellent energy saving performance.MEANS FOR SOLVING THE PROBLEM: The lubricant oil composition is characterized by including: (A) lubricant oil base oil comprising at least one selected from mineral oil, PAO and GTL (Gas to Liquid) base oil and; (B) a polyalkylene glycol (PAG) comprising a structure obtained by the addition polymerization of propylene oxide alone with an alcohol or a structure obtained by the addition polymerization of a combination of propylene oxide, and ethylene oxide and / or butylene oxide with an alcohol, with an oxygen / carbon weight ratio therein being 0.35 or more and less than 0.45, and / or a compound obtained by blocking either or both of the terminal hydroxy groups of the polyalkylene glycol (PAG); and (C) a fatty acid ester with an oxygen / carbon weight ratio therein being from 0.05 to 0.35.SELECTED DRAWING: None

Description

[Technical field]

[0001] The viscosity of lubricating oils normally decreases as the temperature rises. Therefore, generally speaking, the viscosity is high at low temperatures and low at high temperatures. The type of lubricating oil used also differs depending on the environment (particularly temperature) in which it is used. If a low-viscosity lubricating oil is used in both low-temperature and high-temperature environments, the viscosity is too low at high temperatures and causes the oil film to break, while if a high-viscosity lubricating oil is used, the viscosity is too high at low temperatures and can increase mixing losses or prevent pumping, causing seizure and wear.

[0002] It is important for the viscosity to be low when the oil starts to operate (when going from a stopped state to an operating state, i.e., when the temperature is low). If the viscosity is high at the start of operation, an initial operating force is required to change the oil from a stopped state to an operating state. On the other hand, once the machine is running, the viscosity is not as important. As the machine continues to operate, it will generate heat and its temperature will rise (for example, to around 100°C). When the temperature rises, the viscosity will drop too much, as mentioned above, and this can cause the oil film to break.

[0003] Thus, it is difficult to ensure the necessary viscosity over a wide range of temperature conditions with only one lubricant. Therefore, Patent Document 1 discloses a lubricant that functions at both low and high temperatures by combining a low-viscosity lubricant with a high-viscosity lubricant, utilizing only the properties of the low-viscosity lubricant at low temperatures, and utilizing the property that the high-viscosity lubricant increases its viscosity by mixing with the low-viscosity lubricant at high temperatures. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO 96 / 11244 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0005] However, the lubricating oil composition disclosed in Patent Document 1 did not always provide sufficient fuel economy.

[0006] Therefore, an object of the present invention is to provide a novel lubricating oil composition capable of achieving excellent fuel economy. [Means for solving the problem]

[0007] In the above-mentioned prior art documents, the separation temperature of the composition is considered. However, the present inventors have found that in order to improve fuel economy, it may not be sufficient to control the separation temperature of the composition alone, and it is important to control the separation speed of the composition. More specifically, they have found that when the temperature falls below the separation temperature of the composition, the high viscosity component and the low viscosity component quickly separate, and the lubricating state is restored by the low viscosity component, which is important for improving fuel economy.

[0008] Furthermore, based on the above viewpoint, the inventors have found that the above problems can be solved by using a specific base oil and additives as components of a lubricating oil composition, and have completed the present invention.

[0009] The present invention relates to (A) a lubricating base oil comprising at least one selected from mineral oil, PAO and GTL (gas-to-liquid) base oil; (B) a polyalkylene glycol (PAG) having a structure in which propylene oxide is added to an alcohol alone, or in which propylene oxide is added to an alcohol in combination with ethylene oxide and / or butylene oxide, and having an oxygen / carbon weight ratio of 0.35 or more and less than 0.45, and / or a compound in which one or both of the terminal hydroxyl groups of the polyalkylene glycol (PAG) are blocked with a substituent having a molecular weight of 200 or less and consisting of at least one type selected from C, N, O, S and H; (C) a fatty acid ester having an oxygen / carbon weight ratio of 0.05 to 0.35; A lubricating oil composition comprising: The kinetic viscosity of the fatty acid ester at 40°C is 16mm 2 It is preferable that the ratio is 1 / s or more. Effect of the Invention

[0010] It is possible to provide a novel lubricating oil composition that is capable of achieving excellent fuel economy. [Brief description of the drawings]

[0011] [Figure 1] 1 shows a schematic diagram (one example) of a two-layer system of a lubricating oil composition. [Diagram 2] 1 shows an embodiment of the measurement of the separation temperature of a lubricating oil composition. [Diagram 3] 1 is a photograph of an experimental apparatus used in measuring the separation rate of a lubricating oil composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The components, properties / characteristics, production method, applications, etc. of the lubricating oil composition according to the present invention will be described below.

[0013] In the following, when the upper limit and lower limit of a certain numerical range are stated separately, all numerical ranges combining them are deemed to be disclosed. In addition, in the following, "numerical value A to numerical value B" means "numerical value A or more and numerical value B or less." Furthermore, in the following, numerical ranges stated as "greater than" and "less than" can be read as "greater than" and "less than," respectively.

[0014] The kinematic viscosity in the present invention is a value measured in accordance with JIS K2283:2000.

[0015] The oxygen / carbon weight ratio in the present invention represents the ratio of the oxygen weight to the carbon weight in a component, and this value mainly affects the physical properties such as density and polarity of a compound. For example, the polarity is also affected by the type of functional group such as an ether group, an ester group, a hydroxyl group, or a carboxyl group, but since oxygen atoms have a high electronegativity, the polarity generally tends to be higher as the oxygen / carbon weight ratio increases. As for density, since oxygen is heavier than carbon, compounds with a high oxygen / carbon weight ratio generally tend to have a high density. The oxygen / carbon weight ratio can be measured according to JPI-5S-65 (Petroleum products-Testing methods for carbon, hydrogen, and nitrogen content) and JPI-5S-68 (Petroleum products-Testing methods for oxygen content).

[0016] <<<Ingredients>>> The lubricating oil composition is a lubricating oil composition obtained by mixing component (A): a low-viscosity component, component (B): a high-viscosity component, and component (C): a control component. In other words, the lubricating oil composition is a lubricating oil composition that contains at least the low-viscosity component (A), the high-viscosity component (B), and the control component (C). The lubricating oil composition may contain other components. Each component will be described below.

[0017] <<(A) Low viscosity component>> The (A) low viscosity component is a lubricating base oil containing at least one selected from mineral oil, PAO, and GTL (gas-to-liquid) base oil.

[0018] The type of mineral oil is not particularly limited, but preferred examples include paraffinic or naphthenic mineral oils obtained by applying an appropriate combination of one or more refining methods such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing, and clay treatment to a lubricating oil fraction obtained by atmospheric distillation and reduced pressure distillation of crude oil.

[0019] PAO (poly α-olefin) is a homopolymer or copolymer of α-olefin. Examples of α-olefin include compounds with a CC double bond at the terminal, such as butene, butadiene, hexene, cyclohexene, methylcyclohexene, octene, nonene, decene, dodecene, tetradecene, hexadecene, octadecene, and eicosene. These compounds can be used alone or as a mixture of two or more. In addition, as long as the CC double bond is at the terminal, these compounds may have any isomeric structure that can be taken, and may be a branched structure or a straight-chain structure. Two or more of these structural isomers or positional isomers of the double bond can also be used in combination. Of these olefins, those with 5 or less carbon atoms have a low flash point, and those with 31 or more carbon atoms have a high viscosity and are therefore less practical, so it is more preferable to use straight-chain olefins with 6 to 30 carbon atoms.

[0020] GTL base oil is a base oil synthesized by the Fischer-Tropsch process, a technology for converting natural gas into liquid fuel. Compared to mineral oil base oil refined from crude oil, GTL base oil has extremely low sulfur and aromatic content and a very high paraffin composition ratio, so it has excellent oxidation stability and very small evaporation loss, making it suitable for use as a base oil.

[0021] The (A) low viscosity component can be used alone or in combination of two or more kinds.

[0022] The kinetic viscosity of the low-viscosity component (A) at 40°C is preferably 10 mm 2 / s or more 100mm 2 / s or less, more preferably 15 to 80 mm 2 / s, more preferably 25 to 70 mm 2 / s. The kinetic viscosity of the low-viscosity component (A) at 100°C is preferably 1 to 50 mm 2 / s, more preferably 3 to 30 mm 2 / s, more preferably 4 mm 2 / s super 20mm 2 / s. The density of the (A) low viscosity component at 20°C is preferably 0.700 to 1.000 g / cm 3 and more preferably 0.750 to 0.950 g / cm 3 and more preferably 0.800 to 0.880 g / cm 3 It is.

[0023] The (A) low viscosity component may be contained in an amount of preferably 20% by weight or more, more preferably 25% by weight or more, and even more preferably 30% by weight or more, based on the total weight (100% by weight) of the lubricating oil composition.

[0024] <<(B) High viscosity component>> The (B) high-viscosity component is a polyalkylene glycol (PAG) obtained by addition polymerization of an alkylene oxide to an alcohol. The polyalkylene glycol (PAG) may be a compound in which the terminal hydroxyl groups are modified (blocked) by a conventionally known compound within a range in which the basic properties can be maintained. More specifically, the (B) high-viscosity component may be a compound in which one or both of the terminal hydroxyl groups of the polyalkylene glycol (PAG) are blocked with a substituent (hereinafter referred to as a blocking group) having a molecular weight of 200 or less and consisting of at least one selected from C, N, O, S, and H. In this case, the blocking group may be a conventionally known substituent and may have an ester bond, ether bond, etc., but is preferably an alkyl group (for example, C1 to C10, which may be linear or branched), and more preferably a methyl group or an ethyl group. Hereinafter, a compound in which the terminal hydroxyl groups are blocked by a blocking group may be simply referred to as a polyalkylene glycol derivative.

[0025] Examples of polyalkylene glycols and polyalkylene glycol derivatives include those represented by the following formula:

[0026] [ka]

[0027] In the formula, R each independently represents a straight or branched chain hydrocarbon group having C2 to C10, preferably C2 to C8, more preferably C2 to C6, and m represents an integer of 2 to 500, preferably 2 to 400, more preferably 2 to 300. Note that each R does not necessarily have to be a single alkylene, and may be a combination of different alkylenes. Specific examples include the above (RO) m When the block copolymer is a block copolymer of two types of alkylene oxide, the above (RO) m (R 1 O)m1(R 2 O)m2.

[0028] The component (B) is preferably a compound represented by any of the formulas (2) to (4).

[0029] The alkylene oxide constituting the polyalkylene glycol may be one or more, and may be ethylene oxide, propylene oxide, or butylene oxide, either alone or in combination of two or more of these (e.g., ethylene oxide / propylene oxide).The polyalkylene glycol is more preferably one having a structure in which propylene oxide is added to alcohol by polymerization alone, or a structure in which propylene oxide is added to alcohol by polymerization in combination with ethylene oxide and / or butylene oxide.

[0030] The high-viscosity component (B) may be used alone or in combination of two or more kinds.

[0031] The (B) high viscosity component preferably has an oxygen / carbon gravity ratio of 0.35 or more, 0.36 or more, 0.37 or more, or 0.38 or more, and preferably less than 0.45, less than 0.42, or less than 0.40. More specifically, the oxygen / carbon weight ratio of the (B) high-viscosity component is preferably 0.35 or more and less than 0.45, and more preferably 0.38 or more and less than 0.45. In addition, when the (B) high-viscosity component is a compound in which one or both of the terminal hydroxyl groups of a polyalkylene glycol (PAG) are blocked with a blocking group, the blocking group at the end is not to be counted in calculating the oxygen / carbon weight ratio.

[0032] (B) The high-viscosity component preferably has a kinetic viscosity of 100 mm at 40°C. 2 / s or more, preferably 150 mm 2 / s or more, and more preferably 200 mm 2 / s or more. The kinetic viscosity of the (B) high-viscosity component at 100°C is preferably 20 to 5000 mm 2 / s, more preferably 30 to 3000 mm 2 / s, more preferably 40 to 1000 mm 2 / s. (B) The density of the high viscosity component at 20°C is preferably more than 0.950 and less than 1.050 g / cm 3 More preferably, it is 0.960 to 1.030 g / cm 3 and more preferably 0.970 to 1.010 g / cm 3 It is.

[0033] The high viscosity component (B) may be contained in an amount of preferably 3 to 50% by weight, more preferably 5 to 40% by weight, and even more preferably 7 to 30% by weight, based on the total weight (100% by weight) of the lubricating oil composition.

[0034] Such a high viscosity component, when used in combination with a low viscosity component, is substantially immiscible with the low viscosity component at low temperatures, but is miscible with the low viscosity component at high temperatures.

[0035] <<(C) Control Ingredients>> (C) The control component is a fatty acid ester.

[0036] The fatty acid ester preferably has 1 to 3 ester bonds, and more preferably 1 to 2 ester bonds, in one molecule.

[0037] Fatty acid esters are esters of mono- or polycarboxylic acids and mono- or polyhydric alcohols, which may be saturated or unsaturated, and may be linear or branched.

[0038] More specifically, the fatty acid ester is (1) Monoesters which are esters of monovalent carboxylic acids (e.g., formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, hexadecylic acid, heptadecylic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, etc.) with monohydric alcohols (e.g., straight-chain or branched-chain monohydric alcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, etc.); (2) diesters, which are esters of dicarboxylic acids (e.g., linear or branched dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, etc.) with monohydric alcohols (e.g., the above-mentioned monohydric alcohols) and esters of monovalent carboxylic acids (e.g., the above-mentioned monovalent carboxylic acids) with dihydric alcohols (e.g., linear or branched dihydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, neopentylene glycol, hexylene glycol, etc.); (3) Triesters, which are esters of monovalent carboxylic acids (e.g., the above-mentioned monovalent carboxylic acids) and trihydric alcohols (e.g., glycerin, butanetriol, trimethylolpropane) and esters of trivalent carboxylic acids (e.g., citric acid, isocitric acid) and monohydric alcohols (e.g., the above-mentioned monohydric alcohols).

[0039] Examples of fatty acid esters having 4 or more ester bonds in one molecule include esters of tetravalent or higher carboxylic acids (e.g., ethanetetracarboxylic acid, propanetetracarboxylic acid, butanetetracarboxylic acid) and monohydric alcohols (e.g., the monohydric alcohols described above), and esters of monovalent carboxylic acids (e.g., the monovalent carboxylic acids described above) and tetravalent or higher alcohols (e.g., pentaerythritol, dipentaerythritol, sorbitol, and derivatives thereof).

[0040] When the fatty acid ester is an ester of a polyhydric alcohol and a carboxylic acid or an ester of a polyhydric carboxylic acid and an alcohol, all or a part of the hydroxyl groups and carbonyl groups in the molecule may be reacted.

[0041] The control component (C) can be used alone or in combination of two or more kinds.

[0042] The (C) control component preferably has an oxygen / carbon weight ratio of 0.045 or more, 0.055 or more, 0.065 or more, or 0.075 or more, and preferably 0.35 or less, 0.33 or less, 0.31 or less, or 0.30 or less. More specifically, the oxygen / carbon weight ratio of the control component (C) is preferably from 0.055 to 0.35, and more preferably from 0.075 to 0.35.

[0043] The kinetic viscosity of the control component (C) at 40°C is preferably 15 to 80 mm 2 / s, and more preferably 16 to 60 mm 2 / s, and more preferably 17 to 50 mm 2 / s available. The kinetic viscosity of the control component (C) at 100°C is preferably 1 to 30 mm 2 / s, and more preferably 1.5 to 20 mm 2 / s, and more preferably 2 to 10 mm 2 / s. The density of the control component (C) at 20°C is preferably 0.800 to 1.000 g / cm 3 and more preferably 0.825 to 0.980 g / cm 3 and more preferably 0.850 to 0.960 g / cm 3 It is.

[0044] The control component (C) may be contained in an amount of preferably 1 to 65% by weight, more preferably 2 to 60% by weight, and even more preferably 3 to 55% by weight, based on the total weight (100% by weight) of the lubricating oil composition.

[0045] <<Other ingredients>> The lubricating oil composition may contain other known components in addition to those mentioned above depending on the intended use, such as additives such as pour point depressants, antifoaming agents, detergents, dispersants, antiwear agents, metal deactivators, and antioxidants.

[0046] The amount of other components can be, for example, 1 weight % or more, 3 weight % or more, or 5 weight % or more, and 25 weight % or less, 20 weight % or less, or 15 weight % or less, based on the total amount of the lubricating oil composition.

[0047] <Examples of usage> An example of the state of the lubricating oil composition at the beginning of machine use will be described with reference to FIG. 1. FIG. 1 (top) shows one embodiment of the lubricating oil composition, which is a two-layer state 10 at low temperature. The low-viscosity component 20 is located in the upper layer because it is a low-density lubricating oil, and the high-viscosity component 22 is located in the lower layer because it is a high-density lubricating oil. FIG. 1 (bottom left) shows an embodiment in which a machine 1, which is a lubricated object, is used, and the machine is immersed in the upper layer of the lubricating oil composition. At start-up (low temperature), the low-viscosity upper layer 20 mainly contributes to lubrication, and the high-viscosity lower layer 22 hardly contributes to lubrication. At low temperatures, low-viscosity lubricating oil has sufficient performance (viscosity) for lubrication, so the low-viscosity component alone does not impair lubrication performance. FIG. 1 (bottom right) shows a single-layer state 12 that has become hot as a result of continued use. Here, the low-viscosity component 20 and the high-viscosity component 22 are mixed due to the increase in temperature, forming a uniform lubricating oil composition 24. Compared to when only the low-viscosity component 20 is used, the high-viscosity component 22 is mixed in, and the high-viscosity component 22 compensates for the viscosity decrease that accompanies the temperature rise of the low-viscosity component 20, so that problems such as oil film breakage do not occur even at high temperatures. By forming a uniform single-layer system at a temperature above the separation temperature, the high-viscosity component compensates for the viscosity decrease of the low-viscosity component.

[0048] According to the present invention, it is possible to achieve an excellent separation speed while controlling the separation temperature to an arbitrary temperature so that at low temperatures, the low viscosity lubricating oil, which is usually in the upper layer, contributes to the lubrication of the machine, and at high temperatures, a mixture of high viscosity lubricating oil and low viscosity lubricating oil contributes.

[0049] <<Manufacturing method>> The lubricating oil composition can be produced according to a known method, and the components may be mixed appropriately, and the order of mixing is not particularly limited. The additives may be added as a package product in which multiple types are mixed.

[0050] <<Physical properties / properties>> <Separation temperature> The separation temperature of the lubricating oil composition is preferably within the range of 40 to 100°C. The separation temperature is the temperature at which a lubricating oil composition transitions between a single-layer state and a two-layer state, and is the temperature at which cloudiness (precipitate) becomes visible when a lubricating oil composition in a two-layer state is heated to convert it to a single-layer state and then cooled. The separation temperature can be measured by the following method.

[0051] (Method of measuring separation temperature) Measurements are performed using a CORNING PC-420D as a heater. (1) Place 100 g of sample in a 300 ml beaker and place a stirrer 100 in it. (2) Assemble the experimental equipment as shown in Figure 2, and insert a thermocouple 102 connected to a thermometer 101 into the oil to measure the oil temperature. (3) Set the stirring speed of the hot stirrer 103 to 600 rpm. (4) Set the plate temperature to 120°C and heat until the oil temperature reaches 105°C. (5) When the oil temperature reaches 105°C, stop heating and stirring and allow the sample to cool at room temperature. (6) Observe the condition of the sample in the beaker while it is cooling. (7) When the sample in the beaker becomes cloudy (when a precipitate is visible), record the oil temperature and use it as the separation temperature. The separation temperature is determined visually, with reference to the measurement of the aniline point (JIS K 2256).

[0052] <Separation speed> The lubricating oil composition preferably has a separation rate A of more than 10% / min, and more preferably has a separation rate A of more than 10% / min and a separation rate B of more than 30% / min. The separation rate A and separation rate B are measured by the following method.

[0053] (Method of measuring separation speed A and B) This is performed using a tuning fork vibration viscometer SV-10. (1) Place 100 g of sample in a 300 ml beaker and place a stirrer 100 in it. (2) Assemble the experimental equipment as shown in Figure 3 and place the terminals of the vibration viscometer in the oil. (3) Set the stirring speed of the hot stirrer 103 to 600 rpm. (4) Set the plate temperature to 120°C and heat until the oil temperature reaches 105°C. (5) When the oil temperature reaches 105°C, stop heating and stirring and allow the sample to cool at room temperature. (6) After the oil temperature reaches 100°C, the viscosity and the temperature of the oil are measured using a vibration viscometer 80 minutes and 300 minutes later. In order to calculate the kinetic viscosity, the sample is heated and stirred at 70°C to form a single layer, and then the density at 70°C is measured. The density at each temperature is calculated based on JIS2249. (7) The amount of high-viscosity base oil remaining in the low-viscosity base oil was calculated by comparing the kinematic viscosity when the high-viscosity base oil was removed from the sample with the kinematic viscosity of the actual measured value, and the separation rate was calculated using formula 1). The remaining amount was calculated using the estimation method for kinematic viscosity and blend ratio in JIS K2283 Appendix 1. JPEG0007610963000002.jpg15120(8) After the oil temperature reaches 100°C, the separation speed 80 minutes later is separation speed A, and the separation speed 300 minutes later is separation speed B.

[0054] <40℃ kinematic viscosity> The lubricating oil composition preferably has a kinematic viscosity at 40° C. of 10 to 100 mm 2 / s, and more preferably 15 to 80 mm 2 / s, and more preferably 20 to 60 mm 2 / s. The kinetic viscosity at 40°C referred to here means the kinetic viscosity at 40°C of the upper layer when the lubricating oil composition is separated into two layers. <Kinematic viscosity at 100℃> The lubricating oil composition preferably has a kinematic viscosity at 100°C of 1 to 30 mm 2 / s, and more preferably 3 to 20 mm 2 / s, and more preferably 5 to 15 mm 2 / s. The kinetic viscosity at 100°C mentioned here refers to the kinetic viscosity at 100°C when the lubricating oil composition is in a monolayer state in which the upper and lower layers are mixed together.

[0055] <Viscosity index> The viscosity index (VI) of the lubricating oil composition is preferably 50 or greater, more preferably 150 or greater, and even more preferably 200 or greater. The viscosity index is a convenient index that indicates the degree of viscosity change of a lubricating oil caused by temperature change. A high viscosity index means that the change in viscosity with respect to temperature change is small. The viscosity index shown here can be calculated based on the kinetic viscosity at 40°C of the upper layer when the lubricating oil composition is separated into two layers, and the kinetic viscosity at 100°C when the upper and lower layers of the lubricating oil composition are mixed to form a single layer, according to the viscosity index calculation method specified in JIS K2283.

[0056] <<Applications>> The use of the lubricating oil composition is not particularly limited, and it can be used as a lubricating oil for various machines.For example, it is applied to the lubrication of rotating members and sliding members of various vehicles and industrial machines.In particular, it can be used as a lubricating oil for automobile engines (diesel engines, gasoline engines, etc.), transmissions (gear devices, CVT, AT, MT, DCT, Diff, etc.), industrial (construction machinery, agricultural machinery, industrial machinery, gear devices, etc.), bearings (turbines, spindles, machine tools, etc.), hydraulic devices (hydraulic cylinders, door checks, etc.), compressors (compressors, pumps, etc.), etc., which are used in the range of low temperatures (e.g., -40°C) to high temperatures (e.g., 120°C). EXAMPLES

[0057] EXAMPLES Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples in any way.

[0058] <<Lubricating oil composition>> The raw materials shown in the table were mixed to produce lubricating oil compositions according to the examples and comparative examples.

[0059] <<Evaluation>> The lubricating oil compositions were evaluated for kinematic viscosity (40°C, 100°C), separation temperature, and separation speed. The results of each evaluation are shown in Table 1. The evaluation methods for each evaluation item were as described above.

[0060] [Table 1]

[0061] It has been confirmed that the lubricating oil composition according to the present invention has a predetermined separation temperature and an excellent separation speed, and therefore exhibits excellent lubricating performance in response to temperature changes, and as a result, can exhibit excellent fuel economy.

Claims

[Claim 1] (A) a lubricating base oil comprising at least one selected from mineral oil, PAO and GTL (gas-to-liquid) base oil; (B) a polyalkylene glycol (PAG) having a structure obtained by addition polymerization of propylene oxide alone to an alcohol, or a structure obtained by addition polymerization of propylene oxide in combination with ethylene oxide and / or butylene oxide to an alcohol, and having an oxygen / carbon weight ratio of 0.35 or more and less than 0.45, and / or a compound in which one or both of the terminal hydroxyl groups of the polyalkylene glycol (PAG) are blocked with a substituent having a molecular weight of 200 or less and consisting of at least one type selected from C, N, O, S and H; (C) a fatty acid ester having an oxygen / carbon weight ratio of 0.05 to 0.35; Including, The fatty acid ester has a kinematic viscosity at 40°C of 16 mm2 / s or more; A lubricating oil composition having a separation temperature in the range of 40 to 100°C.

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