JPWO2019012861A1 - Method for stabilizing the dispersibility of organic molybdenum compounds in base oil for a long period of time - Google Patents

Abstract

The method of stabilizing the dispersibility of an organic molybdenum compound in a base oil in the low temperature region of the present invention for a long period of time is as follows. It is characterized in that the organic molybdenum compound is dispersed in the base oil by stirring / heating the mixture mixed in the range of 000 mass ppm to a temperature range of 98 to 150 ° C .: R1 to R4 represent a 2-ethylhexyl group.)

Description

  The present invention relates to a method for stabilizing the dispersibility of an organic molybdenum compound in a base oil for a long period of time.

It is well known in the lubricating oil industry that an organic molybdenum compound is an additive for lubricating oil which is excellent in a friction reducing effect, an antioxidant effect, an antiwear effect and the like. In the automobile industry, in particular, fuel efficiency has been highlighted as an important issue due to environmental problems, and it has been attempted to improve fuel efficiency by lowering the viscosity of engine oil or using a friction modifier. Organic molybdenum compounds are often used. Further, among the organic molybdenum compounds, molybdenum dithiocarbamate is an additive exhibiting a good friction reducing property in the "boundary lubrication region" or the "mixed lubrication region" in which the sliding surfaces of two parts are in direct contact with each other. Therefore, it is preferred and often used as an additive for engine oils.
For example, in Patent Document 1, mineral oil and / or synthetic lubricating oil is used as a base oil, molybdenum dithiocarbamate is 50 to 2000 ppm by weight as a molybdenum (Mo) amount, and zinc dithiophosphate is 0.01 to as a phosphorus (P) amount. Disclosed is an engine oil composition containing 0.2 wt% and an ashless organic polysulfide compound in an amount of 0.01 to 0.4 wt% as a sulfur (S) amount.
In Patent Document 2, an engine oil composition obtained by adding the following components to an engine oil base oil selected from mineral oil or synthetic oil: (A) a boron compound derivative of alkenylsuccinimide, boron In an amount of 0.01 to 0.1% by mass, (B) an organic molybdenum compound in an amount of 0.02 to 0.5% by mass, and (C) an alkaline earth metal salt of hydroxybenzoic acid and an alkylphenol. 0.2 to 10% by weight of the sulfurization mixture is disclosed.
Further, in Patent Document 3, a base oil comprising a mineral oil-based lubricating base oil, a synthetic lubricating base oil, or a mixture thereof, molybdenum dithiocarbamate is added in an amount of 200 to 3000 ppm in terms of molybdenum, and alkylenebis (dialkyldithiocarbamate). It contains 150 to 4000 ppm of sulfur and 0.02 to 1.5 mass% of alkaline earth metal salicylate in the amount of sulfated ash, and contains zinc dialkyldithiophosphate in an amount of 800 ppm or less in phosphorus as necessary. Disclosed is an engine oil composition.
Further, Patent Document 4 discloses an engine oil composition containing a lubricating base oil having a kinematic viscosity of 1 to ²⁰ mm ² / s at 100 ° C., molybdenum dithiocarbamate, molybdenum dithiophosphate, and a metal salicylate-based detergent. (Claim 1); The engine oil composition (Claim 3) further comprising a borated ashless dispersant having a boron content of 0.1% by mass or more and 2.0% by mass or less is disclosed.

JP-A-8-073878 JP, 11-269477, A JP, 2004-099676, A JP 2012-102280 A

  However, although molybdenum dithiocarbamate can be expected to have a good friction-reducing effect, its dispersibility in base oil is poor, and therefore it is known that it is difficult to use molybdenum dithiocarbamate in lubricating oil such as engine oil. Has been. If it is possible to improve the dispersibility of such a specific molybdenum dithiocarbamate in the base oil and to disperse it stably in the low temperature range, which is the temperature that is exposed during storage or during use, it can be used for engine oils, etc. It will be possible to use it in a high-concentration composition for the above-mentioned lubricating oil applications, and it may contribute to the improvement of the friction reduction effect and the improvement of fuel efficiency.

  Therefore, the problem to be solved by the present invention is to provide a method for stably dispersing a specific organic molybdenum compound having poor dispersibility in a base oil for a long period of time. A lubricating oil composition having a high reduction effect can be provided.

（式中、Ｒ¹〜Ｒ⁴は、２−エチルヘキシル基を表す。）Therefore, the inventors of the present invention conducted extensive studies and found a method for improving the dispersibility of a specific organic molybdenum compound having poor dispersibility in a base oil in the base oil, and arrived at the present invention.
That is, the present invention is a mixture of a base oil and an organic molybdenum compound represented by the following general formula (1) in a molybdenum content of 200 to 1,000 mass ppm in a temperature range of 98 to 150 ° C. A method for long-term stabilization of the dispersibility of an organomolybdenum compound in a base oil at low temperatures, characterized by dispersing the organomolybdenum compound in the base oil by stirring and heating to:

(In the formula, R ^{1 to} R ⁴ represent a 2-ethylhexyl group.)

  The effect of the present invention is that the organic molybdenum compound represented by the general formula (1), which is known to have a particularly low dispersibility in a base oil, has a good friction reducing effect, and is stable for a long time in the base oil. The present invention provides a method of dispersing a lubricating oil composition having a high friction-reducing effect.

（式中、Ｒ¹〜Ｒ⁴は、２−エチルヘキシル基を表す。）
この有機モリブデン化合物は、良好な摩擦低減効果を有するものの、基油への分散性が良好ではない有機モリブデン化合物である。The method of stabilizing the dispersibility of the organic molybdenum compound in the base oil in the low temperature range (the temperature range of −5 ° C. to 25 ° C.) of the present invention for a long period of time is the organic compound represented by the following general formula (1) It is possible to disperse the organic molybdenum compound in the base oil by stirring and heating the mixture obtained by mixing the molybdenum compound within the range of 200 to 1,000 mass ppm in the range of 98 to 150 ° C. It features:

(In the formula, R ^{1 to} R ⁴ represent a 2-ethylhexyl group.)
This organic molybdenum compound is an organic molybdenum compound that has a good friction reducing effect but does not have good dispersibility in the base oil.

  The method for producing the organic molybdenum compound represented by the general formula (1) is not particularly limited as long as it is a known production method. For example, JP-A-62-81396, JP-A-7-53983, The production methods described in JP-A-8-217782 and JP-A-10-17586 can be mentioned. These technical contents are appropriately incorporated and made a part of this specification.

  In the method of the present invention, the amount of the organic molybdenum compound added to the base oil is in the range of 200 to 1,000 mass ppm in terms of molybdenum content. Above all, 200 to 800 mass ppm is preferable, and 300 to 600 mass ppm is more preferable, because a high friction reducing effect is expected and a long-term stabilizing effect of dispersibility is easily obtained. When the amount is less than 200 mass ppm, a certain degree of dispersibility is exhibited but a practically high friction reducing effect cannot be obtained, and when it exceeds 1,000 mass ppm, the effect of the present invention may not be obtained, which is not preferable. ..

The reason why the method of the present invention is effective is that mixing the organic molybdenum compound represented by the general formula (1) with the base oil at a temperature equal to or higher than the melting temperature of the compound causes some action. It is considered to be caused by this.
The organomolybdenum compound represented by the general formula (1) is a compound having a melting temperature of 100 ° C. or lower. For example, when TG-DTA is measured using an automatic TG (thermogravimetric) / DTA (differential heat) simultaneous measurement device (DTG-60A: manufactured by Shimadzu Corporation), the organic molybdenum compound represented by the general formula (1) can be obtained. The melting temperature can be measured. Using the above device, 11.365 mg of the compound represented by the general formula (1) was weighed into an aluminum cell, and the temperature was raised at 2 ° C./minute under a nitrogen atmosphere at a gas flow rate of 150 ml and a measurement start temperature of 50 ° C., The melting start temperature was 81 ° C, the peak top temperature was 92 ° C, and the melting end temperature was 98 ° C. That is, the organic molybdenum compound represented by the general formula (1) is a compound having a wide range of melting temperatures and starts to melt when the temperature reaches 81 ° C., but the melting temperature is 98 ° C. or higher. I can say. Therefore, in order to reliably obtain the effect of the present invention, the lower limit temperature of the stirring / heating process is 98 ° C. However, regarding the dispersed state (particle size, etc.) of the lubricating oil composition obtained by dispersing the compound in a base oil by the method of the present invention, other than visual confirmation (whether a transparent solution is kept or not) There is no method, and it is unknown how the base oil and the organomolybdenum compound represented by the general formula (1) work by using the method of the present invention. Therefore, the lubricating oil composition obtained by using the method of the present invention has a wear-reducing effect as compared with lubricating oil compositions containing other organic molybdenum compounds that have been frequently used as engine oil additives. Although it is a more improved lubricating oil composition, it cannot be specified in terms of composition, characteristics, properties, etc., and it must be specified as a lubricating oil composition obtained by the method of the present invention.

  Here, the dispersibility (solubility) of many lubricating oil additives in a base oil is usually dependent on temperature. That is, the additive for lubricating oil has higher dispersibility (solubility) in the base oil when the temperature is raised, and when the temperature is thereafter lowered, the additive for lubricating oil which has been dispersed in the base oil at the time of temperature increase is It is common for sedimentation and precipitation to occur as the temperature decreases. However, in the method of the present invention, a mixture of a base oil and an organic molybdenum compound represented by the general formula (1) within a range of 200 to 1,000 mass ppm in molybdenum content is treated at 98 to 150 ° C. When the mixture is stirred and heated to a temperature range, the resulting mixture does not show sedimentation or precipitation even in a low temperature range below room temperature (a temperature range of −5 ° C. to 25 ° C.), and is stable to the organic molybdenum compound for a long period of time. It can be dispersed in oil, and the organic molybdenum compound represented by the general formula (1) can be used as an additive for lubricating oil. Even if the mixture is stirred and heated to a temperature of less than 98 ° C, the organic molybdenum compound represented by the general formula (1) is dispersed in the base oil once by raising the temperature, but it is lower than room temperature (-5 ° C). It is not preferable to set the temperature within a range of up to 25 ° C) because sedimentation / precipitation is observed. Further, when the mixture is stirred and heated to a temperature higher than 150 ° C, the organic molybdenum compound is gradually decomposed, and when the temperature is lower than room temperature (a temperature range of -5 ° C to 25 ° C), the decomposed product is precipitated, which is preferable. Absent. That is, a mixture of a base oil and an organic molybdenum compound represented by the general formula (1) is stirred and heated to a specific temperature range of 98 ° C to 150 ° C to interact with the base oil and reach room temperature or lower. Even when the temperature is in the range of -5 ° C to 25 ° C, the dispersed state can be stably maintained for a long period of time. The preferable temperature range for the stirring / heating process is within the range of 110 to 130 ° C. The holding time at the predetermined temperature in the stirring / heating process is preferably 0.5 to 3 hours, more preferably 1 to 2 hours. Further, the preferable temperature rising rate of the stirring / temperature rising treatment is in the range of 1 to 5 ° C / minute, more preferably 2 to 3 ° C / minute. During the stirring / heating process, the temperature may change within the range of ± 5 ° C of the set value due to the influence of the device setting and the processing environment, but there is substantially no effect and can be ignored. ..

  Next, the base oil that can be used in the present invention is not particularly limited, depending on the intended use and conditions, as appropriate, from mineral base oils, chemically synthesized base oils, animal and vegetable base oils, and mixed base oils thereof. Although it can be selected, the base oil in which the effect of the method of the present invention is most significantly exhibited for the following reasons is a mineral base oil. Generally, the organomolybdenum compound represented by the general formula (1) has very poor dispersibility in mineral base oil. The method of the present invention greatly contributes to the improvement of the dispersibility of the organic molybdenum compound represented by the general formula (1) in the mineral base oil, and gives very good results. Further, the organic molybdenum compound represented by the general formula (1) can be expected to have a good friction reducing effect, but since it has very poor dispersibility in mineral base oil, it is not preferred as an additive for engine oil, for example. Although there was a tendency, by using the method of the present invention, it becomes possible to use it as an additive for engine oil, etc., and obtain a lubricating oil composition (for example, an engine oil composition) having a good friction reducing effect. I can.

  Here, as the mineral base oil, for example, paraffin base crude oil, naphthene base crude oil or intermediate base crude oil is distilled under atmospheric pressure, or distillate obtained by distilling the residual oil of atmospheric distillation under reduced pressure or Refined oils obtained by refining them according to a conventional method, specifically, solvent refined oils, hydrogenated refined oils, dewaxed treated oils, and clay treated oils can be mentioned. Examples of the chemically synthesized base oil include poly-α-olefin, polyisobutylene (polybutene), monoester, diester, polyol ester, silicic acid ester, polyalkylene glycol, polyphenyl ether, silicone, fluorinated compound, alkylbenzene and GTL. Base oils and the like can be mentioned. Among them, poly-α-olefins, polyisobutylene (polybutene), diesters and polyol esters can be generally used, and examples of the poly-α-olefins include 1-hexene. , 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tetradecene and the like polymerized or oligomerized, or those hydrogenated, such as diester, for example, glutaric acid, Adipic acid, azelaic acid, ce Dibasic acids such as basic acid and dodecanedioic acid, and diesters of alcohols such as 2-ethylhexanol, octanol, decanol, dodecanol and tridecanol, and the like can be mentioned. Examples of the polyol ester include neopentyl glycol, trimethylol ethane, and triethyl ethane. Examples include esters of polyols such as methylolpropane, pentaerythritol, dipentaerythritol and tripentaerythritol with fatty acids such as caproic acid, caprylic acid, lauric acid, capric acid, myristic acid, palmitic acid, stearic acid and oleic acid. Be done. Examples of animal and vegetable base oils include castor oil, olive oil, cacao butter, sesame oil, rice bran oil, safflower oil, soybean oil, camellia oil, corn oil, rapeseed oil, palm oil, palm kernel oil, sunflower oil, cottonseed oil and palm. Examples thereof include vegetable oils and fats such as oil, animal fats and oils such as beef tallow, lard, milk fat, fish oil and whale oil. One of these various base oils listed above may be used, or two or more thereof may be appropriately combined and used. From the viewpoint of the dispersibility of the organic molybdenum compound represented by the general formula (1) and the effect of reducing friction, it is preferable to use a base oil containing a mineral base oil as the base oil. At this time, the mineral base oil in the base oil is used. Is not particularly limited, but it is preferably, for example, 50 to 100% by mass, more preferably 70 to 100% by mass, of the total mass of the base oil, and a base oil consisting essentially of mineral base oil. May be used.

  The organic molybdenum compound represented by the general formula (1) used in the present invention further exhibits a synergistic effect when used in combination with a boron-based dispersant, and more effectively improves the effect of the present invention and is stable for a long period of time. Can be dispersed in The boron-based dispersant is not particularly limited as long as it is commonly used in the lubricating oil industry, and for example, a linear or branched alkyl group having 40 to 400 carbon atoms or an alkenyl group can be used. Examples include compounds obtained by reacting a boron compound such as boric acid or borate with a nitrogen-containing compound having at least one in the molecule. Specifically, nitrogen-containing compounds such as succinimide, succinamide, succinic acid ester, succinic acid ester-amide, benzylamine, polyamine, polysuccinimide, and Mannich base, and boron such as boric acid and borate. For example, a compound is allowed to act. When the carbon number of the alkyl group or the alkenyl group is less than 40, the dispersibility of the compound in the base oil may decrease, while when the carbon number of the alkyl group or the alkenyl group exceeds 400, the lubricating oil composition It is not preferable because the low temperature fluidity of the product may deteriorate. The blending amount of these dispersants is 0.5 to 10 mass% with respect to the total amount of the base oil, the organic molybdenum compound represented by the general formula (1), and the boron-based dispersant, and the effect of the present invention can be obtained. From the viewpoint of easy handling, the content is more preferably 1 to 8% by mass, and further preferably 2 to 5% by mass.

  When the organic molybdenum compound represented by the general formula (1) and the boron-based dispersant are used in combination, the order in which they are dispersed in the base oil is not particularly limited, but a higher synergistic effect can be obtained. The organomolybdenum compound represented by the formula (1) and the boron-based dispersant are simultaneously added to the base oil to form a mixture, and the mixture is stirred and heated to a temperature range of 98 ° C to 150 ° C, preferably 110 to 130 ° C. And then dispersed. The holding time at the predetermined temperature in the stirring / heating process is preferably 0.5 to 3 hours, more preferably 1 to 2 hours. Further, the preferable temperature rising rate of the stirring / temperature rising treatment is in the range of 1 to 5 ° C / minute, more preferably 2 to 3 ° C / minute.

  By a method of stabilizing the dispersibility of the organic molybdenum compound in the base oil in the low temperature range of the present invention as described above for a long period of time, a lubricating oil composition or the like that can stably disperse the organic molybdenum compound in the base oil, For example, engine oil lubricating oil, industrial lubricating oil, hydraulic oil lubricating oil, refrigerating machine lubricating oil, etc. can be produced.

  Further, known additives for lubricating oils can be further appropriately used depending on the purpose of use, as long as the effects of the present invention are not impaired. For example, friction reducing agents, antiwear agents, extreme pressure agents. , Metal-based detergents, dispersants other than boron-based dispersants, friction modifiers, viscosity index improvers, pour point depressants, corrosion inhibitors, metal deactivators and defoamers, rust inhibitors, emulsifiers, anti Examples thereof include emulsifiers and antifungal agents.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In the following examples and the like, "%" is based on mass unless otherwise specified.
First, organic molybdenum compounds, boron-based dispersants and base oils used in Examples, Comparative Examples and Reference Examples are shown below.
<Organic molybdenum compound>
Organic molybdenum compound 1
[Organo-molybdenum compound in which R ¹ , R ² , R ³ and R ^{4 of the} general formula (1) are C ₈ H ₁₇ (2-ethylhexyl group)]
Organic molybdenum compound 2
[Organo-molybdenum compound in which R ¹ , R ² , R ³ and R ^{4 in the} general formula (2) are C ₄ H ₉ (butyl group)]
Organic molybdenum compound 3
[Organo-molybdenum compound in which R ¹ , R ² , R ³ and R ^{4 in the} general formula (2) are C ₈ H ₁₇ (n-octyl group)]
Organic molybdenum compound 4
[Organo-molybdenum compound in which R ¹ , R ² , R ³ and R ^{4 of the} general formula (2) are C ₁₃ H ₂₇ (isotridecyl group)]
Organic molybdenum compound 5
[25% by mass of an organic molybdenum compound in which R ¹ , R ² , R ³ , and R ^{4 of the} general formula (1) are C ₈ H ₁₇ (2-ethylhexyl group), and R ¹ , R ² of the general formula (1) , R ³ and R ⁴ are C ₁₃ H ₂₇ (isotridecyl group) in an amount of 25% by mass, and R ¹ and R ^{2 in} the general formula (1) are C ₈ H ₁₇ (2-ethylhexyl group), A mixture of 50% by mass of an organic molybdenum compound in which R ³ and R ⁴ are C ₁₃ H ₂₇ (isotridecyl group)]
<Dispersant>
Dispersant 1 (boron-based dispersant): boration of polyalkenyl succinimide
object
<Base oil>
Base oil 1: Paraffin-based mineral base oil having a kinematic viscosity at 40 ° C of 19.5 mm ² / sec, a kinematic viscosity at 100 ° C of 4.2 mm ² / sec, and a VI of 124.

<Dispersibility test>
A dispersibility test was conducted using the organic molybdenum compound, dispersant, and base oil listed above.
Example 1
A 200 ml flask equipped with a stirrer was charged with 0.19 g of the organic molybdenum compound 1 (400 mass ppm as the Mo content), then the base oil 1 was added until the total amount reached 100 g, and the temperature rising rate was 3 ° C. with stirring. The temperature was raised in minutes. After the temperature reached 120 ° C., the mixture was stirred for 1 hour while maintaining it at 120 ± 5 ° C. to disperse the organic molybdenum compound, and then cooled to room temperature (25 ° C.) to obtain a lubricating oil composition 1. It was Immediately after stirring and heating of the lubricating oil composition 1, after standing still at 25 ° C (room temperature) for 1 day, then at 25 ° C (room temperature) for 4 days, then at 25 ° C (room temperature) for 7 days Then, the storage stability after standing for 14 days at 25 ° C. (room temperature) was visually confirmed, and the state is summarized in Table 1.

Further, in the same manner, the type of the organic molybdenum compound or the temperature of the stirring / heating treatment (100 ° C. in Example 2, 150 ° C. in Example 3, 50 to 180 ° C. in Comparative Example) and each temperature are set values. For the lubricating oil compositions 2 to 10 obtained by changing the holding temperature (each set value ± 5 ° C), the same storage stability test as that for the lubricating oil composition 1 was performed, and Table 1 (Examples) and The results are shown in Table 2 (Comparative Examples and Reference Examples). The storage stability test was evaluated according to the following criteria:
Evaluation A: A transparent solution is maintained (good dispersion state)
Evaluation B: Some turbidity is generated Evaluation C: All is turbidity Evaluation D: Precipitation is generated

  From the results of Tables 1 and 2, it was found that the lubricating oil compositions 1 to 3 obtained in Examples 1 to 3 maintained a good dispersed state. As a reference example, Table 2 also shows the results of the compounding examples in which the organic molybdenum compound 4 and the organic molybdenum compound 5 having good dispersibility in the base oil were used under the condition that the dispersibility in the base oil was good. ..

Then, the dispersibility when a boron-based dispersant was used together was investigated.
Example 4
A 200 ml flask equipped with a stirrer was charged with 0.19 g of organic molybdenum compound 1 (400 mass ppm as Mo content in the lubricating oil composition) and 4.0 g of dispersant 1 (4 mass% in the lubricating oil composition). Then, the base oil 1 was added until the total amount became 100 g, and the temperature was raised at a heating rate of 3 ° C./min while stirring. After the temperature reached 120 ° C., the mixture was stirred at 120 ± 5 ° C. for 1 hour to disperse the organic molybdenum compound and the dispersant, and then cooled to room temperature (25 ° C.) to obtain a lubricating oil composition. I got 11. Immediately after stirring and heating of the obtained lubricating oil composition 11, after standing at 25 ° C. (room temperature) for 1 day, at 25 ° C. (room temperature) for 4 days, at 25 ° C. (room temperature), 7 After standing for one day, the storage stability after standing for 14 days at 25 ° C. (room temperature) was visually confirmed, and the obtained results are shown in Table 3.

Further, in the same manner as in Example 4, the lubricating oil composition 12 in which the addition amount of the organic molybdenum compound was changed to 600 mass ppm as the Mo content and the lubricating oil in which the storage temperature in the storage stability test after stirring and dispersion was changed were changed. The composition 11 ′ was subjected to the same storage stability test as the lubricating oil composition 11, and the obtained results are also shown in Table 3. The storage stability test was evaluated according to the following criteria:
Evaluation A: A transparent solution is maintained (good dispersion state)
Evaluation B: Some turbidity is generated Evaluation C: All is turbidity Evaluation D: Precipitation is generated

  From the results in Table 3, it can be seen that the combined use with the boron-based dispersant improves the dispersibility of the organic molybdenum compound represented by the general formula (1). In Example 6, the obtained lubricating oil composition 11 ′ was allowed to stand at −5 ° C. (room temperature) for 1 day, then at −5 ° C. (room temperature) for 4 days, and then at −5 ° C. (room temperature). ) For 7 days and then visually confirmed for storage stability after storage for 14 days at −5 ° C. (room temperature), and the state was evaluated, and storage stability at low temperature was also good. I knew it was.

<Lubrication characteristics test>
Subsequently, for the lubricating oil composition 1 (Example 1), the lubricating oil composition 11 (Example 6), and the lubricating oil composition 10 (Reference Example 2), which had good results in the solubility test, A lubrication property test was conducted. The test was performed using the samples immediately after the stirring / heating process and after the storage stability test (25 ° C., after 7 days), respectively. The SRV tester (manufactured by Optimol, model: type3) was used as a tester, and the friction coefficient was evaluated by the line contact method (Cylinder on Disk) under the following conditions. Table 4 shows the measured values of the friction coefficient.
Test condition load: 200N
Amplitude: 1.0mm
Frequency: 50Hz
Temperature: 80 ℃
Time: 15 minutes

  From the results of Table 4, as a result, the lubricating oil composition obtained by using the method of the present invention shows a good friction reducing effect immediately after stirring / heating treatment and after storage at 25 ° C. for 7 days. It can be seen that a friction reducing effect superior to that of the lubricating oil composition 10 in which the organic molybdenum compound 5 having good dispersibility in oil is dispersed is obtained.

  INDUSTRIAL APPLICABILITY In the present invention, a good friction reducing effect can be expected, but the organic molybdenum compound represented by the general formula (1), which has poor dispersibility in a base oil and is difficult to use as an additive for lubricating oil, It provides a method for long-term stable dispersion in oil, and is extremely useful, for example, in the future automobile industry, because it greatly contributes to improving fuel efficiency and realizing comfortable driving of cars. It is highly likely.

Claims (4)

A mixture of a base oil and an organic molybdenum compound represented by the following general formula (1) within a range of 200 to 1,000 mass ppm in terms of molybdenum content is stirred and heated to a temperature range of 98 to 150 ° C. Dispersing the organic molybdenum compound in the base oil by the method described above:

(In the formula, R ^{1 to} R ⁴ represent a 2-ethylhexyl group.)   Process according to claim 1, characterized in that the base oil is a base oil comprising a mineral base oil.   The method according to claim 1 or 2, further comprising adding a boron-based dispersant.   A lubricating oil composition obtained by using the method for stabilizing the dispersibility of an organic molybdenum compound in a base oil in a low temperature range according to any one of claims 1 to 3 for a long period of time.