JP2007246661A - Lubricating oil composition for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricating oil composition for an internal combustion engine having excellent heat/oxidation stability and achieving sufficient long draining. <P>SOLUTION: The lubricating oil composition for the internal combustion engine comprises a lubricating base oil satisfying at least either of conditions (a) or (b), an ashless oxidation inhibitor free of sulfur as a constituent element, at least one kind selected from an ashless oxidation inhibitor containing the sulfur as the constituent element, and an organomolybdenum compound. (a) A lubricating base oil containing ≥90 mass% of a saturated component in which the ratio of a cyclic saturated component accounts for 10-40 mass% of the saturated component. (b) A lubricating base oil satisfying conditions represented by formula (1) 1.440≤n<SB>20</SB>-0.002×kv100≤1.453 (1) [wherein, n<SB>20</SB>represents the refractive index of the lubricating base oil at 20°C; and kv100 represents the kinematic viscosity (mm<SP>2</SP>/s) of the lubricating base oil at 100°C]. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lubricating oil composition for an internal combustion engine, and more particularly to a lubricating oil composition for an internal combustion engine that is suitable as a lubricating oil for gasoline engines, methanol-containing fuel-compatible engines, gas engines, and the like.

  Lubricating oils used for internal combustion engines such as automobile engines are required to have thermal and oxidation stability that can withstand long-term use under severe conditions.

Therefore, in a conventional lubricating oil for internal combustion engines, a highly refined base oil such as hydrocracked mineral oil or a high-performance base oil such as synthetic oil is used to ensure thermal and oxidation stability, and dithiophosphorus is used as the base oil. In general, a sulfur-containing compound having a peroxide resolution such as zinc oxide (ZDTP) or molybdenum dithiocarbamate (MoDTC), or an ashless antioxidant such as a phenol-based or amine-based antioxidant is generally used. (For example, see Patent Documents 1 to 4.)
JP-A-4-36391 JP 63-223094 A JP-A-8-302378 JP 9-003463 A

  However, in recent years, in addition to the harsher use conditions of internal combustion engine lubricants, demands for longer drains of lubricants are also required from the viewpoint of effective use of resources, reduction of waste oil, and cost reduction of lubricant users. In order to meet these demands, there is room for improvement even in the conventional lubricating oil for internal combustion engines. That is, according to the study by the present inventors, the lubricating base oil used in the conventional lubricating oil for internal combustion engines has its own thermal and oxidative stability even if it is called a high performance base oil. Not necessarily enough. In addition, it is possible to improve the heat / oxidation stability to some extent by increasing the blending amount of the antioxidant, but the effect of improving the heat / oxidation stability by this method is naturally limited.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a lubricating oil composition for an internal combustion engine that is excellent in thermal and oxidation stability and can achieve a sufficiently long drain. And

  In order to solve the above-mentioned problems, the present invention comprises a lubricating base oil containing 90% by mass or more of a saturated component and 10 to 40% by mass of a cyclic saturated component in the saturated component, and sulfur. Provided is a lubricating oil composition for an internal combustion engine, comprising: an ashless antioxidant not contained as an element; and at least one selected from an ashless antioxidant containing sulfur as a constituent element and an organic molybdenum compound To do.

  Since the lubricating base oil contained in the lubricating oil composition for internal combustion engines of the present invention satisfies the above conditions, the content of the saturated component and the ratio of the cyclic saturated component in the saturated component satisfy the above conditions, respectively.・ Excellent oxidation stability and volatilization prevention. Furthermore, the lubricating base oil, when an additive is blended, can exhibit its function at a higher level while stably dissolving and holding the additive. The lubricating base oil having such excellent characteristics includes an ashless antioxidant that does not contain sulfur as a constituent element (hereinafter sometimes referred to as “component (A)”), and a sulfur base ingredient that does not contain sulfur. By including both of the ash antioxidant and at least one selected from organic molybdenum compounds (hereinafter sometimes referred to as “component (B)”), the heat and heat generated by the synergistic action of components (A) and (B) The effect of improving the oxidation stability can be maximized. Therefore, it is possible to achieve a sufficiently long drain by the lubricating oil composition for an internal combustion engine of the present invention.

  In addition, the lubricating base oil contained in the composition for internal combustion engines of the present invention satisfies the above conditions because the content of the saturated component and the ratio of the cyclic saturated component in the saturated component satisfy the above conditions, respectively. -Excellent temperature characteristics and friction characteristics. Furthermore, the lubricating base oil is excellent in terms of solubility and effectiveness of the additive as described above, and when a friction modifier is blended, the friction reducing effect can be obtained at a high level. is there. Therefore, according to the lubricating oil composition for an internal combustion engine of the present invention including such an excellent lubricating base oil, energy loss due to frictional resistance, stirring resistance, etc. in the sliding portion is reduced, and sufficient energy saving is achieved. Can be achieved.

  Furthermore, in the case of the conventional lubricating base oil, it has been difficult to achieve both the improvement of the low-temperature viscosity characteristics and the prevention of volatilization. However, according to the lubricating base oil of the present invention, the low-temperature viscosity characteristics and volatilization prevention Both can be achieved at a high level and with a good balance. Therefore, the lubricating oil composition for an internal combustion engine of the present invention is useful in terms of improving startability at low temperatures in addition to the long drain and energy saving of the internal combustion engine.

  The present invention also includes a lubricating base oil that satisfies the condition represented by the following formula (1), an ashless antioxidant that does not contain sulfur as a constituent element, an ashless antioxidant that contains sulfur as a constituent element, and Provided is a lubricating oil composition for an internal combustion engine comprising at least one selected from organic molybdenum compounds.

1.440 ≦ n ₂₀ −0.002 × kv100 ≦ 1.453 (1)
_{Wherein, n 20} is the refractive index at 20 ° C. of the lubricating base oil, kv100 represents the kinematic viscosity at 100 ° C. of the lubricating base oil ^(mm 2 / s). ]

  The lubricating base oil that satisfies the condition represented by the above formula (1) is also excellent in thermal and oxidation stability, and in addition to viscosity-temperature characteristics (including low-temperature viscosity characteristics), friction characteristics, and volatilization prevention properties. In addition, when an additive is blended, the function of the additive can be expressed at a higher level while the additive is stably dissolved and held. Therefore, from the lubricating base oil satisfying the condition represented by the above formula (1), the ashless antioxidant not containing sulfur as a constituent element, the ashless antioxidant containing sulfur as a constituent element, and the organic molybdenum compound Even with the lubricating oil composition for an internal combustion engine containing at least one selected from the above, it is possible to achieve a long drain, energy saving, and an improvement in low-temperature startability.

  According to the present invention, a lubricating oil composition for an internal combustion engine that is excellent in thermal / oxidative stability or further in viscosity-temperature characteristics, friction characteristics, and volatilization prevention properties is realized. And, by applying the lubricating oil composition for an internal combustion engine of the present invention to the internal combustion engine, it becomes possible to achieve a long drain and energy saving, and further to improve the low temperature startability. Become.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

In the present invention, a lubricating base oil that satisfies at least one of the following conditions (a) or (b) (hereinafter simply referred to as “the lubricating base oil according to the present invention”) is used. The lubricating base oil according to the present invention only needs to satisfy at least one of the conditions (a) and (b), but it is more preferable to satisfy both the conditions (a) and (b).
(A) It contains 90% by mass or more of the saturated component, and the ratio of the cyclic saturated component in the saturated component is 10 to 40% by mass.
(B) The condition expressed by the following formula (1) is satisfied.
1.440 ≦ n ₂₀ −0.002 × kv100 ≦ 1.453 (1)
_{Wherein, n 20} is the refractive index at 20 ° C. of the lubricating base oil, kv100 represents the kinematic viscosity at 100 ° C. of the lubricating base oil ^(mm 2 / s). ]

  The lubricating base oil according to the present invention is not particularly limited as long as it satisfies at least one of the above conditions (a) and (b). Specifically, a lubricating oil fraction obtained by atmospheric distillation and / or vacuum distillation of crude oil is subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid Of the paraffinic mineral oil, or the normal paraffinic base oil, the isoparaffinic base oil, etc. purified by combining one or more of the purification treatments such as washing and clay treatment alone or in combination of the above conditions (a) or Those satisfying at least one of (b) are mentioned. These lubricating base oils may be used alone or in combination of two or more.

As a preferable example of the lubricating base oil according to the present invention, the following base oils (1) to (8) are used as raw materials, and the raw oil and / or the lubricating oil fraction recovered from the raw oil is determined in advance. The base oil obtained by refine | purifying by the refining method of this, and collect | recovering lubricating oil fractions can be mentioned.
(1) Distilled oil by atmospheric distillation of paraffinic crude oil and / or mixed base crude oil (2) Distilled oil by vacuum distillation of atmospheric distillation residue of paraffinic crude oil and / or mixed base crude oil ( WVGO)
(3) Wax (slack wax, etc.) obtained by the lubricant dewaxing process and / or synthetic wax (Fischer-Tropsch wax, GTL wax, etc.) obtained by the gas-to-liquid (GTL) process, etc.
(4) One or two or more mixed oils selected from base oils (1) to (3) and / or mild hydrocracking treatment oils of the mixed oils (5) selected from base oils (1) to (4) 2 or more kinds of mixed oils (6) Base oil (1), (2), (3), (4) or (5) debris oil (DAO)
(7) Mild hydrocracking treatment oil (MHC) of base oil (6)
(8) Two or more mixed oils selected from base oils (1) to (7).

  The above-mentioned predetermined purification methods include hydrorefining such as hydrocracking and hydrofinishing; solvent refining such as furfural solvent extraction; dewaxing such as solvent dewaxing and catalytic dewaxing; acid clay and activated clay White clay purification; chemical (acid or alkali) cleaning such as sulfuric acid cleaning and caustic soda cleaning is preferable. In the present invention, one of these purification methods may be performed alone, or two or more may be combined. Moreover, when combining 2 or more types of purification methods, the order in particular is not restrict | limited, It can select suitably.

Furthermore, the lubricating base oil according to the present invention is obtained by subjecting a base oil selected from the above base oils (1) to (8) or a lubricating oil fraction recovered from the base oil to a predetermined treatment. The following base oil (9) or (10) is particularly preferred.
(9) The base oil selected from the base oils (1) to (8) or the lubricating oil fraction recovered from the base oil is hydrocracked and recovered from the product or the product by distillation or the like. Hydrocracked mineral oil obtained by performing dewaxing treatment such as solvent dewaxing or catalytic dewaxing on the lubricating oil fraction, or by distillation after the dewaxing treatment (10) The above base oils (1) to (8) ) Or a lubricating oil fraction recovered from the base oil is hydroisomerized, and the product or the lubricating oil fraction recovered from the product by distillation or the like is subjected to solvent dewaxing or catalytic dewaxing. Hydroisomerized mineral oil obtained by performing a dewaxing process such as or by distillation after the dewaxing process.

  Moreover, when obtaining the lubricating base oil of (9) or (10) above, a solvent refining treatment and / or a hydrofinishing treatment step may be further provided as necessary at a convenient step.

  The catalyst used for the hydrocracking / hydroisomerization is not particularly limited, but a composite oxide having cracking activity (for example, silica alumina, alumina boria, silica zirconia, etc.) or one of the composite oxides. Hydrogenolysis with a combination of the above combined with a binder and supporting a metal having hydrogenation ability (for example, one or more metals such as Group VIa metal or Group VIII metal in the periodic table) Hydroisomerization catalyst in which a catalyst or a support containing zeolite (for example, ZSM-5, zeolite beta, SAPO-11, etc.) is loaded with a metal having a hydrogenation ability containing at least one of Group VIII metals Are preferably used. The hydrocracking catalyst and the hydroisomerization catalyst may be used in combination by stacking or mixing.

  The reaction conditions in the hydrocracking / hydroisomerization are not particularly limited, but the hydrogen partial pressure is 0.1 to 20 MPa, the average reaction temperature is 150 to 450 ° C., the LHSV is 0.1 to 3.0 hr-1, and the hydrogen / oil ratio. It is preferable to set it as 50-20000 scf / b.

  Preferable examples of the method for producing a lubricating base oil according to the present invention include production method A shown below.

That is, the manufacturing method A according to the present invention includes:
NH ₃ to the carrier desorption of the fraction of the NH ₃ is 80% or less at 300 to 800 ° C. relative to the total desorption of NH ₃ in the desorption temperature dependence evaluation, at least one of the periodic table Group VIa metals And a first step of preparing a hydrocracking catalyst on which at least one of the Group VIII metals is supported,
In the presence of a hydrocracking catalyst, a feed oil containing 50% by volume or more of slack wax, hydrogen partial pressure 0.1-14 MPa, average reaction temperature 230-430 ° C., LHSV 0.3-3.0 hr ⁻¹ , hydrogen oil ratio A second step of hydrocracking at 50-14000 scf / b;
A third step of obtaining a lubricating oil fraction by distilling and separating the cracked product oil obtained in the second step;
And a fourth step of dewaxing the lubricating oil fraction obtained in the third step.

  Hereinafter, the production method A will be described in detail.

(Raw oil)
In the production method A, a raw material oil containing 50% by volume or more of slack wax is used. The “raw oil containing 50% by volume or more of slack wax” as used in the present invention is a mixed oil of a raw oil consisting only of slack wax, slack wax and other raw material oil, and 50 volumes of slack wax. % And both raw material oils containing at least% are included.

Slack wax is a wax-containing component by-produced in the solvent dewaxing step when producing a lubricating base oil from a paraffinic lubricating oil fraction. In the present invention, the slack wax is obtained by further deoiling the wax-containing component. Included in wax. The main components of slack wax are n-paraffins and branched paraffins (isoparaffins) with few side chains, and are low in naphthenes and aromatics. The kinematic viscosity of the slack wax used for the preparation of the raw material oil can be appropriately selected according to the kinematic viscosity of the target lubricating base oil, but a low viscosity base oil is produced as the lubricating base oil according to the present invention. For this purpose, a relatively low viscosity slack wax having a kinematic viscosity at 100 ° C. of about ² to 25 mm ² / s, preferably about 2.5 to ²⁰ mm ² / s, more preferably about 3 to 15 mm ² / s. desirable. Moreover, although the other property of slack wax is also arbitrary, melting | fusing point becomes like this. Preferably it is 35-80 degreeC, More preferably, it is 45-70 degreeC, More preferably, it is 50-60 degreeC. The oil content of the slack wax is preferably 60% by mass or less, more preferably 50% by mass or less, further preferably 25% by mass or less, particularly preferably 10% by mass or less, and preferably 0.5% by mass. As mentioned above, More preferably, it is 1 mass% or more. The sulfur content of the slack wax is preferably 1% by mass or less, more preferably 0.5% by mass or less, and preferably 0.001% by mass or more.

  Here, the oil content of the fully deoiled slack wax (hereinafter referred to as “slack wax A”) is preferably 0.5 to 10% by mass, more preferably 1 to 8% by mass. The sulfur content of the slack wax A is preferably 0.001 to 0.2% by mass, more preferably 0.01 to 0.15% by mass, and still more preferably 0.05 to 0.12% by mass. On the other hand, the oil content of slack wax (hereinafter referred to as “slack wax B”) that is not deoiled or insufficiently deoiled is preferably 10 to 60% by mass, more preferably 12 to 50% by mass. More preferably, it is 15 to 25% by mass. The sulfur content of the slack wax B is preferably 0.05 to 1% by mass, more preferably 0.1 to 0.5% by mass, and still more preferably 0.15 to 0.25% by mass.

  In the production method A, by using the slack wax A as a raw material, the lubricating base oil according to the present invention satisfying at least one of the conditions (a) and (b) can be suitably obtained. In addition, according to the above production method A, even if slack wax B having a relatively high oil content and sulfur content, and relatively poor and inexpensive is used as a raw material, the viscosity index is high, and low temperature characteristics and thermal / oxidative stability are excellent. In addition, a lubricating base oil with high added value can be obtained.

  When the raw material oil is a mixed oil of slack wax and other raw material oil, the other raw material oil is not particularly limited as long as the ratio of slack wax to the total amount of the mixed oil is 50% by volume or more. A heavy oil-distilled distillate and / or a mixed oil of vacuum-distilled distillate is preferably used.

  Further, when the raw material oil is a mixed oil of slack wax and another raw material oil, the ratio of slack wax in the mixed oil is more preferably 70% by volume or more from the viewpoint of producing a base oil having a high viscosity index. 75% by volume or more is even more preferable. When the ratio is less than 50% by volume, the oil base such as aromatics and naphthenes in the obtained lubricating base oil tends to increase and the viscosity index of the lubricating base oil tends to decrease.

  On the other hand, the heavy atmospheric distillation distillate and / or vacuum distillation distillate of crude oil used in combination with slack wax has a distillation temperature of 300 to 570 ° C. in order to keep the viscosity index of the lubricating base oil produced high. A fraction having a distillate component of 60% by volume or more in the range is preferable.

(Hydrocracking catalyst)
In the manufacturing method A, the carrier desorption of the fraction of the NH ₃ is 80% or less at 300 to 800 ° C. relative to the total desorption of NH ₃ in the NH ₃ desorption temperature dependence evaluation, periodic table Group VIa A hydrocracking catalyst in which at least one of the metals and at least one of the Group VIII metals is supported is used.

Here, “NH ₃ desorption temperature dependency evaluation” refers to literature (Sawa M., Niwa M., Murakami Y., Zeolites 1990, 10, 532, Karge HG, Dondur V., J. Phys. Chem., 1990, 94, 765, etc.) and is performed as follows. First, the catalyst carrier is pretreated at a temperature of 400 ° C. or higher for 30 minutes or more under a nitrogen stream to remove adsorbed molecules, and then adsorbs NH ₃ at 100 ° C. until saturation. Then, the catalyst support to 100 to 800 ° C. 10 ° C. / min was heated by the following heating rate desorbed NH _3, to monitor the NH ₃ separated at every predetermined temperature by desorption. Then, the fraction of the NH ₃ desorption amount at 300 ° C. to 800 ° C. with respect to the total NH ₃ desorption amount (desorption amount at 100 to 800 ° C.) is obtained.

The catalyst carrier used in the production method A are those desorption of the fraction of NH ₃ at 300 to 800 ° C. relative to the total desorption of NH ₃ in the NH ₃ desorption temperature dependence evaluation of the following 80% , Preferably 70% or less, more preferably 60% or less. By constituting a hydrocracking catalyst using such a carrier, the acid properties that govern the cracking activity are sufficiently suppressed, so that the high molecular weight n-paraffin derived from slack wax or the like in the raw oil by hydrocracking. The production of isoparaffin by decomposition isomerization can be performed efficiently and reliably, and excessive decomposition of the produced isoparaffin compound can be sufficiently suppressed. As a result, a sufficient amount of molecules having a moderately branched chemical structure and a high viscosity index can be provided in an appropriate molecular weight range.

  As such a support, a binary oxide which is amorphous and has an acid property is preferable. For example, it is exemplified in the literature ("Metal oxide and its catalytic action", Tetsuro Shimizu, Kodansha, 1978). And binary oxides.

Among them, an amorphous composite oxide which is an acid composed of two kinds of oxides of elements selected from Al, B, Ba, Bi, Cd, Ga, La, Mg, Si, Ti, W, Y, Zn and Zr. It is preferable to contain a property binary oxide. By adjusting the ratio of each oxide of these acid property binary oxides, a support having an acid property suitable for this purpose can be obtained in the NH ₃ adsorption / desorption evaluation. In addition, the acid property binary oxide constituting the carrier may be one of the above or a mixture of two or more. Further, the carrier may be composed of the above-mentioned acid property binary oxide, or may be a carrier obtained by binding the acid property binary oxide with a binder.

  Further, the carrier is amorphous silica / alumina, amorphous silica / zirconia, amorphous silica / magnesia, amorphous silica / titania, amorphous silica / boria, amorphous alumina / zirconia, amorphous alumina / magnesia, amorphous At least one selected from alumina / titania, amorphous alumina / boria, amorphous zirconia / magnesia, amorphous zirconia / titania, amorphous zirconia / boria, amorphous magnesia / titania, amorphous magnesia / boria and amorphous titania / boria It is preferable to contain two kinds of acid nature binary oxides. The acidic binary oxide constituting the carrier may be one of the above or a mixture of two or more. Further, the carrier may be composed of the above-mentioned acid property binary oxide, or may be a carrier obtained by binding the acid property binary oxide with a binder. The binder is not particularly limited as long as it is generally used for catalyst preparation, but is preferably selected from silica, alumina, magnesia, titania, zirconia, clay, or a mixture thereof.

  In the production method A described above, the carrier is composed of at least one of group VIa metals (molybdenum, chromium, tungsten, etc.) of the periodic table and group VIII metal (nickel, cobalt, palladium, platinum, etc.). At least one of them is supported to form a hydrocracking catalyst. These metals are responsible for hydrogenation ability, terminate the reaction in which the paraffinic compound is decomposed or branched by the acidic carrier, and play an important role in producing isoparaffin having an appropriate molecular weight and branched structure.

  As the amount of metal supported in the hydrocracking catalyst, the supported amount of Group VIa metal is 5 to 30% by mass per one type of metal, and the supported amount of Group VIII metal is 0.2 to 10% by mass per one type of metal. % Is preferred.

  Further, in the hydrocracking catalyst used in the production method A, molybdenum is contained in the range of 5 to 30% by mass as one or more metals of the Group VIa metal, and one or more of the Group VIII metals is contained. More preferably, the metal contains nickel in the range of 0.2 to 10% by mass.

  The hydrocracking catalyst composed of the above support and one or more metals of Group VIa metal and one or more metals of Group VIII metal is preferably used for hydrocracking in a sulfurized state. The sulfurization treatment can be performed by a known method.

(Hydrolysis process)
In the production method A, a raw material oil containing 50% by volume or more of slack wax in the presence of the hydrocracking catalyst has a hydrogen partial pressure of 0.1 to 14 MPa, preferably 1 to 14 MPa, more preferably 2 to 2. 7 MPa; average reaction temperature of 230 to 430 ° C., preferably 330 to 400 ° C., more preferably 350 to 390 ° C .; LHSV of 0.3 to 3.0 hr ⁻¹ , preferably 0.5 to 2.0 hr ⁻¹ ; Hydrogenolysis is performed at a hydrogen oil ratio of 50 to 14,000 scf / b, preferably 100 to 5000 scf / b.

  In such a hydrocracking process, isomerization to isoparaffin progresses in the process of cracking n-paraffin derived from slack wax in the raw material oil, thereby producing an isoparaffin component having a low pour point and a high viscosity index. At the same time, it breaks down aromatic compounds, which are inhibitors of high viscosity index contained in the feedstock, into monocyclic aromatic compounds, naphthene compounds and paraffin compounds, and inhibits high viscosity index. The polycyclic naphthene compound as a factor can be decomposed into a monocyclic naphthene compound or a paraffin compound. From the viewpoint of increasing the viscosity index, it is preferable that the raw material oil contains fewer compounds having a high boiling point and a low viscosity index.

Further, the decomposition rate for evaluating the progress of the reaction is expressed by the following formula:
(Decomposition rate (volume%)) = 100− (ratio of the fraction having a boiling point of 360 ° C. or more in the product (volume%))
In this way, the decomposition rate is preferably 3 to 90% by volume. When the decomposition rate is less than 3% by volume, isoparaffins are generated by decomposition and isomerization of high-molecular-weight n-paraffins having a high pour point contained in the feedstock, and hydrocracking of aromatics and polycyclic naphthenes with poor viscosity index. When the decomposition rate exceeds 90% by volume, the yield of the lubricating oil fraction decreases, which is not preferable.

(Distillation separation process)
Next, the lubricating oil fraction is distilled and separated from the cracked product oil obtained by the hydrocracking step. At this time, a fuel oil fraction may be obtained as a light component.

  The fuel oil fraction is a fraction obtained as a result of sufficient desulfurization and denitrogenation, and sufficient aromatic hydrogenation. Among these, the naphtha fraction has a high isoparaffin content, the kerosene fraction has a high smoke point, and the light oil fraction has a high cetane number.

  On the other hand, when hydrocracking in the lubricating oil fraction is insufficient, a part of it may be subjected to the hydrocracking process again. Further, in order to obtain a lubricating oil fraction having a desired kinematic viscosity, the lubricating oil fraction may be further distilled under reduced pressure. This vacuum distillation separation may be performed after the dewaxing treatment described below.

  In the evaporative separation step, a lubricant base oil called 70 Pale, SAE10, or SAE20 can be suitably obtained by distilling the cracked product oil obtained in the hydrocracking step under reduced pressure.

  A system that uses slack wax with lower viscosity as the feedstock is suitable for producing a large amount of 70 Pale and 10 SAE fractions, and a system that uses slack wax with a high viscosity within the above range as feedstock produces a lot of SAE20. Suitable for doing. However, even if a high-viscosity slack wax is used, conditions for generating a considerable amount of 70 Pale and SAE 10 can be selected depending on the progress of the decomposition reaction.

(Dewaxing process)
In the above-described distillation separation step, since the lubricating oil fraction fractionated from the cracked product oil has a high pour point, it is dewaxed to obtain a lubricating base oil having a desired pour point. The dewaxing treatment can be performed by a usual method such as a solvent dewaxing method or a contact dewaxing method. Among these, the solvent dewaxing method generally uses a mixed solvent of MEK and toluene, but may use a solvent such as benzene, acetone, MIBK or the like. In order to make the pour point of the dewaxed oil not more than −10 ° C., the solvent / oil ratio is 1 to 6 times, and the filtration temperature is −5 to −45 ° C., preferably −10 to −40 ° C. The wax removed here can be used again as a slack wax in the hydrocracking step.

  In the said manufacturing method, you may add a solvent refinement | purification process and / or a hydrorefining process to a dewaxing process. These additional treatments are performed in order to improve the ultraviolet stability and oxidation stability of the lubricating base oil, and can be carried out by a method used in a normal lubricating oil refining process.

  In the solvent purification, furfural, phenol, N-methylpyrrolidone or the like is generally used as a solvent, and a small amount of aromatic compounds, particularly polycyclic aromatic compounds remaining in the lubricating oil fraction are removed.

In addition, hydrorefining is performed to hydrogenate olefin compounds and aromatic compounds, and the catalyst is not particularly limited. However, at least one of Group VIa metals such as molybdenum, cobalt, nickel, etc. Using an alumina catalyst supporting at least one of the Group VIII metals, the reaction pressure (hydrogen partial pressure) is 7 to 16 MPa, the average reaction temperature is 300 to 390 ° C., and the LHSV is 0.5 to 4.0 hr ⁻¹ . Can be done below.

  Moreover, as a preferable example of the manufacturing method of the lubricating base oil according to the present invention, the following manufacturing method B can be mentioned.

That is, the production method B according to the present invention is:
A fifth step of hydrocracking and / or hydroisomerizing a feedstock containing paraffinic hydrocarbons in the presence of a catalyst;
A sixth step of dewaxing the product obtained in the fifth step or the lubricating oil fraction recovered from the product by distillation or the like;
Is provided.

  Hereinafter, the production method B will be described in detail.

(Raw oil)
In the production method B, a raw material oil containing paraffinic hydrocarbon is used. The “paraffinic hydrocarbon” referred to in the present invention means a hydrocarbon having a paraffin molecule content of 70% by mass or more. The carbon number of the paraffinic hydrocarbon is not particularly limited, but usually about 10 to 100 is used. The paraffinic hydrocarbon production method is not particularly limited, and various paraffinic hydrocarbons such as petroleum and synthetic can be used. Particularly preferable paraffinic hydrocarbons include a gas-liquid (GTL) process and the like. Synthetic waxes obtained (Fischer-Tropsch wax (FT wax), GTL wax, etc.) can be mentioned, among which FT wax is preferred. The synthetic wax is preferably a wax containing, as a main component, a normal paraffin having 15 to 80 carbon atoms, more preferably 20 to 50 carbon atoms.

The kinematic viscosity of the paraffinic hydrocarbon used in the preparation of the raw material oil can be appropriately selected according to the kinematic viscosity of the target lubricating base oil, but the low viscosity base oil is used as the lubricating base oil according to the present invention. To produce a relatively low viscosity paraffin having a kinematic viscosity at 100 ° C. of about ² to 25 mm ² / s, preferably about 2.5 to ²⁰ mm ² / s, more preferably about 3 to 15 mm ² / s. Series hydrocarbons are desirable. In addition, other properties of the paraffinic hydrocarbon are optional, but when the paraffinic hydrocarbon is a synthetic wax such as FT wax, the melting point is preferably 35 to 80 ° C, more preferably 50 to 80 ° C, More preferably, it is 60-80 degreeC. The oil content of the synthetic wax is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 2% by mass or less. Further, the sulfur content of the synthetic wax is preferably 0.01% by mass or less, more preferably 0.001% by mass or less, and still more preferably 0.0001% by mass or less.

  When the raw material oil is a mixed oil of the above synthetic wax and another raw material oil, the other raw material oil is not particularly limited as long as the ratio of the synthetic wax to the total amount of the mixed oil is 50% by volume or more. A heavy atmospheric distillation oil and / or a mixed oil of reduced pressure distillation oil is preferably used.

  Further, when the raw material oil is a mixed oil of the above synthetic wax and other raw material oils, the proportion of the synthetic wax in the mixed oil is more than 70% by volume from the viewpoint of producing a base oil having a high viscosity index. Preferably, 75% by volume or more is even more preferable. If the ratio is less than 70% by volume, the lubricating base oil to be obtained tends to increase the oil content such as aromatics and naphthenes and decrease the viscosity index of the lubricating base oil.

  On the other hand, heavy crude pressure distillation distillate and / or vacuum distillation distillate of crude oil used in combination with synthetic wax is used at a distillation temperature of 300 to 570 ° C. in order to keep the viscosity index of the lubricating base oil to be produced high. A fraction having a distillate component of 60% by volume or more in the range is preferable.

(catalyst)
The catalyst used in production method B is not particularly limited, but a catalyst in which at least one selected from Group VI metal and Group VIII metal of the periodic table as an active metal component is supported on a support containing aluminosilicate. Preferably used.

  Aluminosilicate refers to a metal oxide composed of three elements of aluminum, silicon, and oxygen. Further, other metal elements can be allowed to coexist within a range that does not hinder the effects of the present invention. In this case, the amount of the other metal element is preferably 5% by mass or less, and more preferably 3% by mass or less of the total amount of alumina and silica as the oxide. Examples of metal elements that can coexist include titanium, lanthanum, manganese, and the like.

The crystallinity of aluminosilicate can be estimated by the proportion of tetracoordinate aluminum atoms in all aluminum atoms, and this proportion can be measured by ²⁷ Al solid state NMR. As the aluminosilicate used in the present invention, the ratio of tetracoordinated aluminum to the total amount of aluminum is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more. Hereinafter, an aluminosilicate in which the ratio of tetracoordinated aluminum to the total amount of aluminum is 50% by mass or more is referred to as “crystalline aluminosilicate”.

  As the crystalline aluminosilicate, so-called zeolite can be used. Preferable examples include Y-type zeolite, ultra-stable Y-type zeolite (USY-type zeolite), β-type zeolite, mordenite, ZSM-5, etc. Among them, USY zeolite is particularly preferable. In the present invention, one type of crystalline aluminosilicate may be used alone, or two or more types may be used in combination.

  Examples of a method for preparing a carrier containing crystalline aluminosilicate include a method of molding a mixture of crystalline aluminosilicate and a binder and firing the molded body. The binder to be used is not particularly limited, but alumina, silica, silica alumina, titania and magnesia are preferable, and alumina is particularly preferable. The use ratio of the binder is not particularly limited, but is usually preferably 5 to 99% by mass and more preferably 20 to 99% by mass based on the total amount of the molded body. 430-470 degreeC is preferable, as for the baking temperature of the molded object containing a crystalline aluminosilicate and a binder, 440-460 degreeC is more preferable, and 445-455 degreeC is more preferable. The firing time is not particularly limited, but is usually 1 minute to 24 hours, preferably 10 minutes to 20 hours, more preferably 30 minutes to 10 hours. Firing may be performed in an air atmosphere, but is preferably performed in an oxygen-free atmosphere such as a nitrogen atmosphere.

  Examples of the Group VI b metal supported on the carrier include chromium, molybdenum, tungsten, and the like. Specific examples of the Group VIII metal include cobalt, nickel, rhodium, palladium, iridium, platinum, and the like. It is done. These metals may be used individually by 1 type, or may be used in combination of 2 or more types. When two or more kinds of metals are combined, noble metals such as platinum and palladium may be combined, base metals such as nickel, cobalt, tungsten, and molybdenum may be combined, or a noble metal and a base metal may be combined.

  Further, the loading of the metal on the carrier can be performed by information such as impregnation of the carrier into a solution containing the metal, ion exchange, and the like. The amount of the metal supported can be appropriately selected, but is usually 0.05 to 2% by mass, preferably 0.1 to 1% by mass based on the total amount of the catalyst.

(Hydrolysis / Hydroisomerization process)
In the production method B, the feedstock oil containing paraffinic hydrocarbon is hydrocracked / hydroisomerized in the presence of the catalyst. Such hydrocracking / hydroisomerization step can be performed using a fixed bed reactor. As conditions for hydrocracking / hydroisomerization, for example, the temperature is preferably 250 to 400 ° C., the hydrogen pressure is preferably 0.5 to 10 MPa, and the liquid space velocity (LHSV) of the feedstock is preferably 0.5 to 10 h ^−1. .

(Distillation separation process)
Next, the lubricating oil fraction is distilled and separated from the cracked product oil obtained by the hydrocracking / hydroisomerization step. In addition, since the distillation separation process in the manufacturing method B is the same as the distillation separation process in the manufacturing method A, the overlapping description is abbreviate | omitted here.

(Dewaxing process)
Subsequently, the lubricating oil fraction fractionated from the cracked product oil in the distillation separation step is dewaxed. Such a dewaxing step can be performed using a conventionally known dewaxing process such as solvent dewaxing or catalytic dewaxing. Here, if the substance having a boiling point of 370 ° C. or less present in the cracked / isomerized product oil is not separated from the high boiling point substance prior to dewaxing, depending on the use of the cracked / isomerized product oil, The compound may be dewaxed or a fraction having a boiling point of 370 ° C. or higher may be dewaxed.

  In solvent dewaxing, the hydroisomerized product is contacted with chilled ketone and acetone, and other solvents such as MEK, MIBK, and further cooled to precipitate the high pour point material as a waxy solid, which is precipitated with raffinate. Separate from a solvent-containing lubricating oil fraction. Further, the raffinate can be cooled with a scraped surface chiller to remove wax solids. Low molecular weight hydrocarbons such as propane can also be used for dewaxing. In this case, the cracked / isomerized product oil and the low molecular weight hydrocarbon are mixed and at least a part thereof is vaporized to decompose / isomerize. The product oil is further cooled to precipitate the wax. The wax is separated from the raffinate by filtration, membrane or centrifugation. Thereafter, the solvent is removed from the raffinate, and the raffinate is fractionally distilled to obtain the target lubricating base oil.

  In the case of catalytic dewaxing (catalyst dewaxing), the cracked / isomerized product oil is reacted with hydrogen in the presence of a suitable dewaxing catalyst under conditions effective to lower the pour point. In catalytic dewaxing, some of the high-boiling substances in the cracking / isomerization product are converted to low-boiling substances, the low-boiling substances are separated from the heavier base oil fraction, and the base oil fraction is fractionated. Two or more kinds of lubricating base oils are obtained. The low-boiling substances can be separated before obtaining the target lubricating base oil or during fractional distillation.

  The dewaxing catalyst is not particularly limited as long as it can lower the pour point of the cracked / isomerized product oil, but the desired lubricating base oil is obtained from the cracked / isomerized product oil in a high yield. Those that can be used are preferred. As such a dewaxing catalyst, a shape selective molecular sieve (molecular sieve) is preferable, and specifically, ferrierite, mordenite, ZSM-5, ZSM-11, ZSM-23, ZSM-35, ZSM-22 ( And theta aluminophosphates (SAPO) and the like. These molecular sieves are preferably used in combination with a catalytic metal component, and more preferably in combination with a noble metal. A preferable combination includes, for example, a composite of platinum and H-mordenite.

The dewaxing conditions are not particularly limited, but the temperature is preferably 200 to 500 ° C., and the hydrogen pressure is preferably 10 to 200 bar (1 MPa to 20 MPa). In the case of a flow-through reactor, the H ₂ treatment rate is preferably 0.1 to 10 kg / l / hr, and the LHSV is preferably 0.1 to 10 ^{−1 and} more preferably 0.2 to 2.0 h ^−1. . Dewaxing refers to a substance having an initial boiling point of 350 to 400 ° C., usually 40% by mass or less, preferably 30% by mass or less, contained in the cracked / isomerized product oil, having a boiling point lower than the initial boiling point. It is preferable to carry out the conversion to a substance having the same.

  As mentioned above, although the manufacturing method A and the manufacturing method B which are the preferable manufacturing methods of the lubricant base oil concerning this invention were demonstrated, the manufacturing method of the lubricant base oil concerning this invention is not limited to these. For example, in the above production method A, synthetic waxes such as FT wax and GTL wax may be used instead of slack wax. In the production method B, a raw material oil containing slack wax (preferably slack wax A, B) may be used. Furthermore, in each of the production methods A and B, slack wax (preferably slack wax A and B) and synthetic wax (preferably FT wax and GTL wax) may be used in combination.

  In addition, when the raw material oil used when manufacturing the lubricating base oil according to the present invention is a mixed oil of the above-described slack wax and / or synthetic wax and a raw material oil other than these waxes, slack wax The content of the synthetic wax is preferably 50% by mass or more based on the total amount of the raw material oil.

  Further, when producing a lubricating base oil satisfying the above condition (a), the raw oil is a raw oil containing slack wax and / or synthetic wax, and the oil content is 0 to 60% by mass, preferably A raw material oil containing 10 to 50% by mass is preferred; a raw material oil containing slack wax A and / or slack wax B, wherein the oil content is 0.5 to 60% by mass, preferably 10 to 50%. More preferably; a raw material oil containing slack wax B, in which the oil content is 5 to 60% by mass, preferably 10 to 50% by mass, is particularly preferable.

  In addition, when the lubricating base oil according to the present invention satisfies the above condition (a), the saturated content in the lubricating base oil is 90 mass as described above based on the total amount of the lubricating base oil. % Or more, preferably 95% by mass or more, more preferably 96% by mass or more, and still more preferably 97% by mass or more. Moreover, the ratio of the cyclic | annular saturated part which occupies for the said saturated part is 10-40 mass% as above-mentioned, Preferably it is 10.5-30 mass%, More preferably, it is 11-25 mass%, More preferably, it is 12-21. % By mass. Viscosity-temperature characteristics and thermal / oxidative stability can be achieved by satisfying the above conditions for the content of the saturated component and the ratio of the cyclic saturated component in the saturated component, respectively. When the additive is blended, the function of the additive can be expressed at a higher level while the additive is sufficiently stably dissolved and held in the lubricating base oil. Furthermore, when the content of the saturated component and the ratio of the cyclic saturated component in the saturated component satisfy the above conditions, the friction characteristics of the lubricating base oil itself can be improved, and as a result, the friction reducing effect is improved. As a result, energy saving can be improved.

  If the saturated content is less than 90% by mass, the viscosity-temperature characteristics, thermal / oxidation stability, and friction characteristics will be insufficient. Further, when the ratio of the cyclic saturated component to the saturated component is less than 10% by mass, when the additive is blended with the lubricating base oil, the solubility of the additive may be insufficient, Since the effective amount of the additive dissolved and retained in the oil base oil is reduced, the function of the additive cannot be effectively obtained. Furthermore, when the ratio of the cyclic saturated component in the saturated component exceeds 40% by mass, the effectiveness of the additive is reduced when the additive is blended with the lubricating base oil. Further, the content of the saturated component may be 100% by mass, but is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, from the viewpoint of reducing the production cost and improving the solubility of the additive. More preferably, it is 99 mass% or less, Most preferably, it is 98.5 mass% or less.

  When the lubricating base oil according to the present invention satisfies the above condition (a), the proportion of the cyclic saturated component in the saturated component is 10 to 40% by mass. Is equivalent to 60 to 90% by mass. Here, the non-cyclic saturated component includes both a linear paraffin component and a branched paraffin component. The proportion of each paraffin component in the lubricating base oil according to the present invention is not particularly limited, but the proportion of the branched paraffin component is preferably 55 to 99 mass%, more preferably 57. It is 5-95 mass%, More preferably, it is 60-95 mass%, More preferably, it is 70-90 mass%, Most preferably, it is 80-90 mass%. When the ratio of the branched paraffin content in the lubricating base oil satisfies the above conditions, the viscosity-temperature characteristics and thermal / oxidative stability can be further improved, and an additive is added to the lubricating base oil. In this case, the function of the additive can be expressed at a higher level while the additive is sufficiently stably dissolved and held.

  In addition, content of the saturated part said by this invention means the value (unit: mass%) measured based on ASTM D 2007-93.

  Moreover, the ratio of the cyclic saturated component and the non-cyclic saturated component in the saturated component referred to in the present invention is a naphthene component measured according to ASTM D 2786-91, respectively (measuring object: 1-ring to 6-ring naphthene, unit : Mass%) and alkane content (unit: mass%).

In addition, the linear paraffin content in the lubricating base oil referred to in the present invention is the gas chromatographic analysis of the saturated content separated and separated by the method described in ASTM D 2007-93 under the following conditions. The value obtained by converting the measured value when the linear paraffin content in the saturated content is identified and quantified based on the total amount of the lubricating base oil is meant. In the identification and quantification, a mixed sample of straight-chain paraffin having 5 to 50 carbon atoms is used as a standard sample, and the straight-chain paraffin content in the saturated portion is the total peak area value of the chromatogram (in the diluent). It is determined as the ratio of the sum of peak area values corresponding to each linear paraffin to (excluding the peak area value derived from).
(Gas chromatography conditions)
Column: non-polar liquid phase column (length 25 mm, inner diameter 0.3 mmφ, liquid phase film thickness 0.1 μm)
Temperature rising condition: 50 ° C. to 400 ° C. (temperature rising rate: 10 ° C./min)
Carrier gas: helium (linear velocity: 40 cm / min)
Split ratio: 90/1
Sample injection amount: 0.5 μL (injection amount of sample diluted 20 times with carbon disulfide)

  The ratio of branched paraffin in the lubricating base oil is the difference between the non-cyclic saturated content in the saturated content and the linear paraffin content in the saturated content, converted based on the total amount of the lubricating base oil. Means the value.

  In the case of a method for separating saturated components, or a compositional analysis of cyclic saturated components, non-cyclic saturated components, etc., a similar method can be used in which similar results can be obtained. For example, in addition to the above, a method described in ASTM D 2425-93, a method described in ASTM D 2549-91, a method using high performance liquid chromatography (HPLC), a method obtained by improving these methods, and the like can be given.

Further, when the lubricating base oil according to the present invention satisfies the above condition (b), n ₂₀ −0.002 × kv100 is 1.440 to 1.453 as described above, preferably 1. 441 to 1.453, more preferably 1.443 to 1.452, and still more preferably 1.444 to 1.450. _By setting n ₂₀ −0.002 × kv100 within the above range, excellent viscosity-temperature characteristics and thermal / oxidative stability can be achieved, and an additive is blended in the lubricating base oil. In this case, the function of the additive can be expressed at a higher level while the additive is sufficiently stably dissolved and held in the lubricating base oil. Furthermore, by setting n ₂₀ −0.002 × kv100 within the above range, the friction characteristics of the lubricating base oil itself can be improved, and as a result, an improvement in friction reduction effect and an improvement in energy saving can be achieved. can do.

When n ₂₀ −0.002 × kv100 exceeds the upper limit, the viscosity-temperature characteristics, thermal / oxidation stability, and friction characteristics become insufficient, and further, an additive is blended in the lubricating base oil. In some cases, the effectiveness of the additive is reduced. Further, when n ₂₀ −0.002 × kv100 is less than the lower limit, when an additive is blended in the lubricating base oil, the solubility of the additive becomes insufficient, and the lubricating base oil contains Since the effective amount of the additive that is dissolved and held is lowered, the function of the additive cannot be effectively obtained.

In addition, the refractive index (n20) in ₂₀ degreeC said by this invention means the refractive index measured in 20 degreeC based on ASTMD1218-92. The kinematic viscosity (kv100) at 100 ° C. in the present invention means a kinematic viscosity measured at 100 ° C. in accordance with JIS K 2283-1993.

  The aromatic content in the lubricating base oil according to the present invention is not particularly limited as long as the lubricating base oil satisfies at least one of the above conditions (a) or (b), but based on the total amount of the lubricating base oil. The content is preferably 10% by mass or less, more preferably 0.1 to 5% by mass, still more preferably 0.2 to 4.5% by mass, and particularly preferably 0.3 to 3% by mass. If the aromatic content exceeds the above upper limit, the viscosity-temperature characteristics, thermal / oxidative stability, friction characteristics, volatilization prevention characteristics and low-temperature viscosity characteristics tend to decrease. When an additive is blended with the additive, the effectiveness of the additive tends to decrease. Moreover, the lubricating base oil according to the present invention may not contain an aromatic component, but by further increasing the solubility of the additive by setting the aromatic content to the above lower limit or more. Can do.

  In addition, content of an aromatic content here means the value measured based on ASTM D 2007-93. In general, the aromatic component includes alkylbenzene, alkylnaphthalene, anthracene, phenanthrene and alkylated products thereof, as well as compounds in which four or more benzene rings are condensed, pyridines, quinolines, phenols and naphthols. Aromatic compounds having atoms are included.

Further, the% C _p of the lubricating base oil according to the present invention is not particularly limited as long as the lubricating base oil satisfies at least one of the above conditions (a) or (b), but is preferably 80 or more. Preferably it is 82-99, More preferably, it is 85-95, Most preferably, it is 87-93. When% C _p of lubricating base oil is less than the above lower limit, viscosity-temperature characteristics, thermal / oxidative stability, and friction characteristics tend to decrease, and further, additives are added to lubricating base oil In addition, the effectiveness of the additive tends to decrease. Further, when the% C _p value of the lubricating base oil exceeds the upper limit value, the additive solubility will tend to be lower.

Moreover,% C _N of the lubricating base oil according to the present invention is a lubricating oil base oil is not particularly limited so long as it satisfies at least one of the conditions (a) or (b), preferably 19 or less, more Preferably it is 5-15, More preferably, it is 7-13, Most preferably, it is 8-12. With% C _N of the lubricating base oil exceeds the upper limit value, the viscosity - temperature characteristic, heat and oxidation stability and frictional properties will tend to be reduced. Moreover, when% _CN is less than the said lower limit, it exists in the tendency for the solubility of an additive to fall.

Moreover,% C _A of the lubricating base oil according to the present invention is a lubricating oil base oil is not particularly limited so long as it satisfies at least one of the conditions (a) or (b), preferably 5 or less, more Preferably it is 2 or less, more preferably 1.5 or less, particularly preferably 1 or less. When% C _A of the lubricating base oil exceeds the upper limit value, the viscosity - temperature characteristic, heat and oxidation stability and frictional properties will tend to be reduced. Moreover,% C _A of the lubricating base oil according to the present invention may be 0% by 0.1 or more C _A, it is possible to further increase the solubility of additives.

Furthermore, the ratio of the% C _P and% C _N of the lubricating base oil according to the present invention is a lubricating oil base oil is not particularly limited so long as it satisfies at least one of the conditions (a) or (b) % preferably C P _/% C _N is 5 or more, more preferably 6 or more, more preferably 7 or more. When% C _P /% _CN is less than the above lower limit value, viscosity-temperature characteristics, thermal / oxidative stability and friction characteristics tend to decrease, and further, when an additive is blended in the lubricating base oil In addition, the effectiveness of the additive tends to decrease. _{Moreover,% C} P /% C _N is preferably 35 or less, more preferably 20 or less, further preferably 14 or less, and particularly preferably 13 or less. % Of C P _/% C _N by the above-described upper limit or less, it is possible to further increase the solubility of additives.

Incidentally, _say% C P in the present invention,% _C A _N and% _{C A,} obtained by a method in accordance with ASTM D 3238-85, respectively (n-d-M ring analysis), the total carbon number of the paraffin carbon number The percentage of the total number of naphthene carbons to the total number of carbons, and the percentage of the total number of aromatic carbons to the total number of carbons. That is, the preferred ranges of% C _P ,% C _N and% C _A described above are based on the values obtained by the above method. For example, even a lubricating base oil containing no naphthene is obtained by the above method. is% C _N may indicate a value greater than zero.

  Further, the content of sulfur in the lubricating base oil according to the present invention depends on the content of sulfur in the raw material. For example, when a raw material that does not substantially contain sulfur such as a synthetic wax component obtained by a Fischer-Tropsch reaction or the like is used, a lubricating base oil that does not substantially contain sulfur can be obtained. In addition, when using raw materials containing sulfur such as slack wax obtained in the refining process of the lubricating base oil and microwax obtained in the refining process, the sulfur content in the obtained lubricating base oil is usually 100 mass ppm. That's it. In the lubricating base oil according to the present invention, the content of sulfur is preferably 100 ppm by mass or less, more preferably 50 ppm by mass or less, from the viewpoint of further improvement in thermal and oxidation stability and low sulfur content. More preferably, it is more preferably 10 ppm by mass or less, and particularly preferably 5 ppm by mass or less.

  Further, from the viewpoint of cost reduction, it is preferable to use slack wax or the like as a raw material. In that case, the sulfur content in the obtained lubricating base oil is preferably 50 ppm by mass or less, and preferably 10 ppm by mass or less. More preferred. In addition, the sulfur content as used in the field of this invention means the sulfur content measured based on JISK2541-1996.

  The nitrogen content in the lubricating base oil according to the present invention is not particularly limited, but is preferably 5 ppm by mass or less, more preferably 3 ppm by mass or less, and further preferably 1 ppm by mass or less. If the nitrogen content exceeds 5 ppm by mass, the thermal and oxidation stability tends to decrease. In addition, the nitrogen content as used in the field of this invention means the nitrogen content measured based on JISK2609-1990.

The kinematic viscosity of the lubricating base oil according to the present invention is not particularly limited as long as the lubricating base oil satisfies at least one of the above conditions (a) or (b). , Preferably 1.5 to ²⁰ mm ² / s, more preferably 2.0 to 11 mm ² / s. When the kinematic viscosity at 100 ° C. of the lubricating base oil is less than 1.5 mm ² / s, it is not preferable in terms of evaporation loss. In addition, when trying to obtain a lubricating base oil having a kinematic viscosity at 100 ° C. exceeding 20 mm ² / s, the yield decreases, and the decomposition rate can be increased even when heavy wax is used as a raw material. Since it becomes difficult, it is not preferable.

In the present invention, it is preferable to use a lubricating base oil having a kinematic viscosity at 100 ° C. in the following range by distillation or the like.
(I) less than the kinematic viscosity at 100 ° C. is 1.5 mm ² / s or more 3.5 mm ² / s, more preferably kinematic viscosity at 2.0 to 3.0 mm ² / s lubricating base oils (II) 100 ° C. There 3.0 mm ² / s or more 4.5mm less than ² / s, more preferably a kinematic viscosity at 3.5~4.1mm ² / s lubricating base oil (III) 100 ℃ 4.5~20mm ² / s, more preferably 4.8 to 11 mm ² / s, particularly preferably 5.5 to 8.0 mm ² / s.

Moreover, the kinematic viscosity at 40 ° C. of the lubricating base oil according to the present invention is preferably 6.0 to 80 mm ² / s, more preferably 8.0 to 50 mm ² / s. In the present invention, it is preferred that a lubricating oil fraction having a kinematic viscosity at 40 ° C. in the following range is fractionated by distillation or the like and used.
(IV) less than the kinematic viscosity at 40 ° C. is 6.0 mm ² / s or more 12 mm ² / s, more preferably 8.0~12mm ² / s lubricating base oil (V) kinematic viscosity at 40 ° C. is 12 mm ² / More than s and less than 28 mm < ² > / s, more preferably 13-19 mm < ² > / s lubricating base oil (VI) The kinematic viscosity at 40 [deg.] C. is 28-50 mm < ² > / s, more preferably 29-45 mm < ² > / s, particularly preferred. Is a lubricating base oil of 30 to 40 mm ² / s.

  The lubricating base oils (I) and (IV) satisfy at least one of the above conditions (a) or (b), and in particular, have a low temperature viscosity as compared with conventional lubricating base oils having the same viscosity grade. It has excellent characteristics and can significantly reduce viscosity resistance and stirring resistance. Moreover, the BF viscosity in -40 degreeC can be 2000 mPa * s or less by mix | blending a pour point depressant. The BF viscosity at −40 ° C. means the viscosity measured according to JPI-5S-26-99.

  In addition, the lubricating base oil (II) and (V) satisfy at least one of the above conditions (a) or (b), in particular, compared with the conventional lubricating base oil having the same viscosity grade, Excellent low-temperature viscosity characteristics, volatilization prevention and lubricity. For example, in the lubricating base oils (II) and (V), the CCS viscosity at −35 ° C. can be set to 3000 mPa · s or less.

  The lubricating base oils (III) and (VI) satisfy at least one of the above conditions (a) or (b), so that the low temperature viscosity is lower than that of conventional lubricating base oils having the same viscosity grade. Excellent properties, volatilization prevention, thermal / oxidation stability and lubricity.

  The viscosity index of the lubricating base oil according to the present invention depends on the viscosity grade of the lubricating base oil. For example, the viscosity index of the lubricating oils (I) and (IV) is preferably 105 to 130, more preferably. Is 110 to 125, more preferably 120 to 125. The viscosity index of the lubricating base oils (II) and (V) is preferably 125 to 160, more preferably 130 to 150, and still more preferably 135 to 150. Further, the viscosity index of the lubricating base oils (III) and (VI) is preferably 135 to 180, more preferably 140 to 160. When the viscosity index is less than the lower limit, viscosity-temperature characteristics, thermal / oxidation stability, and further volatilization prevention properties tend to decrease. On the other hand, when the viscosity index exceeds the upper limit, the low-temperature viscosity characteristics tend to decrease.

  In addition, the viscosity index as used in the field of this invention means the viscosity index measured based on JISK2283-1993.

  Further, the refractive index at 20 ° C. of the lubricating base oil according to the present invention depends on the viscosity grade of the lubricating base oil, and for example, the refractive index at 20 ° C. of the lubricating base oils (I) and (IV). Is preferably 1.440 to 1.460, more preferably 1.442 to 1.458, and still more preferably 1.445 to 1.455. Moreover, the refractive index at 20 ° C. of the lubricating base oils (II) and (V) is preferably 1.450 to 1.465, more preferably 1.452 to 1.460, still more preferably 1.453 to 1.458. Further, the refractive index of the lubricating base oils (III) and (VI) at 20 ° C. is preferably 1.455 to 1.468, more preferably 1.458 to 1.466, and still more preferably 1.457 to 1.465. If the refractive index exceeds the above upper limit, the viscosity-temperature characteristics and thermal / oxidative stability of the lubricating base oil tend to be reduced, and further, the volatilization preventing properties and low-temperature viscosity characteristics tend to deteriorate. When an additive is blended with the additive, the effectiveness of the additive tends to decrease.

  Further, the pour point of the lubricating base oil according to the present invention depends on the viscosity grade of the lubricating base oil. For example, the pour point of the lubricating base oils (I) and (IV) is preferably −10. ° C or lower, more preferably -12.5 ° C or lower, still more preferably -15 ° C or lower. The pour points of the lubricating base oils (II) and (V) are preferably −10 ° C. or lower, more preferably −15 ° C. or lower, and still more preferably −17.5 ° C. or lower. The pour point of the lubricating base oils (III) and (VI) is preferably −10 ° C. or lower, more preferably −12.5 ° C. or lower, and still more preferably −15 ° C. or lower. When the pour point exceeds the upper limit, the low temperature fluidity of the entire lubricating oil using the lubricating base oil tends to decrease. In addition, the pour point as used in the field of this invention means the pour point measured based on JISK2269-1987.

  Further, the CCS viscosity of the lubricating base oil according to the present invention at −35 ° C. depends on the viscosity grade of the lubricating base oil, but for example, the lubricating base oils (I) and (IV) at −35 ° C. The CCS viscosity is preferably 1000 mPa · s or less. The CCS viscosity at −35 ° C. of the lubricating base oils (II) and (V) is preferably 3000 mPa · s or less, more preferably 2400 mPa · s or less, still more preferably 2200 mPa · s or less, and particularly preferably 2000 mPa · s. -S or less. Further, the CCS viscosity of the lubricating base oils (III) and (VI) at −35 ° C. is preferably 15000 mPa · s or less, more preferably 10000 mPa · s or less, and further preferably 8000 mPa · s or less. When the CCS viscosity at −35 ° C. exceeds the upper limit, the low-temperature fluidity of the entire lubricating oil using the lubricating base oil tends to decrease. In addition, the CCS viscosity at −35 ° C. in the present invention means a viscosity measured according to JIS K 2010-1993.

Further, the density (ρ ₁₅ , unit: g / cm ³ ) of the lubricating base oil according to the present invention at 15 ° C. depends on the viscosity grade of the lubricating base oil, but the value of ρ represented by the following formula (2) It is preferable that ρ ₁₅ ≦ ρ.
ρ = 0.0025 × kv100 + 0.820 (2)
[Wherein, kv100 represents the kinematic viscosity (mm ² / s) of the lubricating base oil at 100 ° C. ]

When ρ ₁₅ > ρ, the viscosity-temperature characteristics and thermal / oxidation stability, volatilization prevention properties and low-temperature viscosity characteristics tend to decrease, and additives are added to the lubricating base oil. In some cases, the effectiveness of the additive tends to decrease.

For example, ρ ₁₅ of the lubricating base oils (I) and (IV) is preferably 0.830 g / cm ³ or less, more preferably 0.825 g / cm ³ or less, and still more preferably 0.820 g / cm ³ or less. It is. The ρ ₁₅ of the lubricating base oils (II) and (V) is preferably 0.835 g / cm ³ or less, more preferably 0.830 g / cm ³ or less. The ρ ₁₅ of the lubricating base oils (III) and (VI) is preferably 0.840 g / cm ³ or less, more preferably 0.835 g / cm ³ or less.

  In addition, the density in 15 degreeC said by this invention means the density measured in 15 degreeC based on JISK2249-1995.

Further, the aniline point (AP (° C.)) of the lubricating base oil according to the present invention depends on the viscosity grade of the lubricating base oil, but is not less than the value of A represented by the following formula (3). It is preferable that ≧ A.
A = 4.1 × kv100 + 97 (3)
[Wherein, kv100 represents the kinematic viscosity (mm ² / s) of the lubricating base oil at 100 ° C. ]

  When AP <A, viscosity-temperature characteristics and thermal / oxidative stability, volatilization prevention properties and low-temperature viscosity characteristics tend to decrease, and when additives are added to the lubricating base oil In addition, the effectiveness of the additive tends to decrease.

  For example, the AP of the lubricating base oils (I) and (IV) is preferably 108 ° C. or higher, more preferably 110 ° C. or higher, and still more preferably 112 ° C. or higher. The AP of the lubricating base oils (II) and (V) is preferably 113 ° C. or higher, more preferably 116 ° C. or higher, still more preferably 118 ° C. or higher, and particularly preferably 120 ° C. or higher. The AP of the lubricating base oils (III) and (VI) is preferably 125 ° C. or higher, more preferably 127 ° C. or higher, and still more preferably 128 ° C. or higher. In addition, the aniline point as used in the field of this invention means the aniline point measured based on JISK2256-1985.

  Further, the NOACK evaporation amount of the lubricating base oil according to the present invention is not particularly limited. For example, the NOACK evaporation amount of the lubricating base oils (I) and (IV) is preferably 20% by mass or more, more preferably. Is 25 mass% or more, more preferably 30 or more, preferably 50 mass% or less, more preferably 45 mass% or less, and still more preferably 42 mass% or less. The NOACK evaporation amount of the lubricating base oils (II) and (V) is preferably 6% by mass or more, more preferably 8% by mass or more, still more preferably 10% by mass or more, and preferably 20%. It is not more than mass%, more preferably not more than 16 mass%, still more preferably not more than 15 mass%, particularly preferably not more than 14 mass%. Further, the NOACK evaporation amount of the lubricating base oils (III) and (VI) is preferably 1% by mass or more, more preferably 2% by mass or more, and preferably 8% by mass or less, more preferably 6%. It is at most 4% by mass, more preferably at most 4% by mass. When the NOACK evaporation amount is the lower limit value, it tends to be difficult to improve the low temperature viscosity characteristics. Further, when the NOACK evaporation amount exceeds the upper limit value, when the lubricating base oil is used as the lubricating oil for an internal combustion engine, the evaporation loss amount of the lubricating oil increases, and accordingly, catalyst poisoning is promoted. Therefore, it is not preferable. In addition, the NOACK evaporation amount as used in the field of this invention means the evaporation loss amount measured based on ASTM D 5800-95.

  Further, the distillation properties of the lubricating base oil according to the present invention are preferably gas chromatography distillation, wherein the initial boiling point (IBP) is 290 to 440 ° C. and the end point (FBP) is 430 to 580 ° C., and such a distillation range. The base oils (I) to (III) and (IV) to (VI) having the preferred viscosity ranges described above are obtained by rectifying one or more fractions selected from the fractions in be able to.

  For example, regarding the distillation properties of the lubricating base oils (I) and (IV), the initial boiling point (IBP) is preferably 260 to 360 ° C, more preferably 300 to 350 ° C, and still more preferably 310 to 350 ° C. It is. Moreover, 10% distillation temperature (T10) becomes like this. Preferably it is 320-400 degreeC, More preferably, it is 340-390 degreeC, More preferably, it is 350-380 degreeC. The 50% distillation point (T50) is preferably 350 to 430 ° C, more preferably 360 to 410 ° C, and still more preferably 370 to 400 ° C. Moreover, 90% distillation point (T90) becomes like this. Preferably it is 380-460 degreeC, More preferably, it is 390-450 degreeC, More preferably, it is 400-440 degreeC. Moreover, an end point (FBP) becomes like this. Preferably it is 420-520 degreeC, More preferably, it is 430-500 degreeC, More preferably, it is 440-480 degreeC. Moreover, T90-T10 becomes like this. Preferably it is 50-100 degreeC, More preferably, it is 55-85 degreeC, More preferably, it is 60-70 degreeC. Moreover, FBP-IBP becomes like this. Preferably it is 100-250 degreeC, More preferably, it is 110-220 degreeC, More preferably, it is 120-200 degreeC. Moreover, T10-IBP becomes like this. Preferably it is 10-80 degreeC, More preferably, it is 15-60 degreeC, More preferably, it is 20-50 degreeC. Moreover, FBP-T90 becomes like this. Preferably it is 10-80 degreeC, More preferably, it is 15-70 degreeC, More preferably, it is 20-60 degreeC.

  Moreover, regarding the distillation properties of the lubricating base oils (II) and (V), the initial boiling point (IBP) is preferably 300 to 380 ° C, more preferably 320 to 370 ° C, still more preferably 330 to 360 ° C. It is. Moreover, 10% distillation temperature (T10) becomes like this. Preferably it is 340-420 degreeC, More preferably, it is 350-410 degreeC, More preferably, it is 360-400 degreeC. The 50% distillation point (T50) is preferably 380 to 460 ° C, more preferably 390 to 450 ° C, and still more preferably 400 to 460 ° C. Moreover, 90% distillation point (T90) becomes like this. Preferably it is 440-500 degreeC, More preferably, it is 450-490 degreeC, More preferably, it is 460-480 degreeC. Moreover, an end point (FBP) becomes like this. Preferably it is 460-540 degreeC, More preferably, it is 470-530 degreeC, More preferably, it is 480-520 degreeC. Moreover, T90-T10 becomes like this. Preferably it is 50-100 degreeC, More preferably, it is 60-95 degreeC, More preferably, it is 80-90 degreeC. Moreover, FBP-IBP becomes like this. Preferably it is 100-250 degreeC, More preferably, it is 120-180 degreeC, More preferably, it is 130-160 degreeC. Moreover, T10-IBP becomes like this. Preferably it is 10-70 degreeC, More preferably, it is 15-60 degreeC, More preferably, it is 20-50 degreeC. Moreover, FBP-T90 becomes like this. Preferably it is 10-50 degreeC, More preferably, it is 20-40 degreeC, More preferably, it is 25-35 degreeC.

  Further, regarding the distillation properties of the lubricating base oils (III) and (VI), the initial boiling point (IBP) is preferably 320 to 480 ° C, more preferably 350 to 460 ° C, still more preferably 380 to 440 ° C. It is. Moreover, 10% distillation temperature (T10) becomes like this. Preferably it is 420-500 degreeC, More preferably, it is 430-480 degreeC, More preferably, it is 440-460 degreeC. The 50% distillation point (T50) is preferably 440 to 520 ° C, more preferably 450 to 510 ° C, and still more preferably 460 to 490 ° C. Moreover, 90% distillation point (T90) becomes like this. Preferably it is 470-550 degreeC, More preferably, it is 480-540 degreeC, More preferably, it is 490-520 degreeC. Moreover, an end point (FBP) becomes like this. Preferably it is 500-580 degreeC, More preferably, it is 510-570 degreeC, More preferably, it is 520-560 degreeC. Moreover, T90-T10 becomes like this. Preferably it is 50-120 degreeC, More preferably, it is 55-100 degreeC, More preferably, it is 55-90 degreeC. Moreover, FBP-IBP becomes like this. Preferably it is 100-250 degreeC, More preferably, it is 110-220 degreeC, More preferably, it is 115-200 degreeC. Moreover, T10-IBP becomes like this. Preferably it is 10-100 degreeC, More preferably, it is 15-90 degreeC, More preferably, it is 20-50 degreeC. Moreover, FBP-T90 becomes like this. Preferably it is 10-50 degreeC, More preferably, it is 20-40 degreeC, More preferably, it is 25-35 degreeC.

  In each of the lubricating base oils (I) to (VI), IBP, T10, T50, T90, FBP, T90-T10, FBP-IBP, T10-IBP, and FBP-T90 are set to the above preferable ranges. Further, it is possible to further improve the low temperature viscosity and further reduce the evaporation loss. In addition, about each of T90-T10, FBP-IBP, T10-IBP, and FBP-T90, when the distillation range is made too narrow, the yield of lubricating base oil is deteriorated, which is not preferable in terms of economy. .

  In the present invention, IBP, T10, T50, T90 and FBP mean distillate points measured in accordance with ASTM D 2887-97, respectively.

  Further, the residual metal content in the lubricating base oil according to the present invention is derived from the metal content contained in the catalyst and raw materials that are inevitably mixed in the manufacturing process, but it is preferable that the residual metal content be sufficiently removed. . For example, the contents of Al, Mo, and Ni are each preferably 1 mass ppm or less. If the content of these metals exceeds the above upper limit, the function of the additive blended with the lubricating base oil tends to be inhibited.

  In addition, the residual metal content as used in the field of this invention means the metal content measured based on JPI-5S-38-2003.

  Moreover, according to the lubricating base oil of the present invention, excellent thermal and oxidation stability can be achieved by satisfying at least one of the above conditions (a) or (b). Accordingly, it is preferable to show the RBOT life shown below. For example, the RBOT life of the lubricating base oils (I) and (IV) is preferably 290 min or more, more preferably 300 min or more, and further preferably 310 min or more. The RBOT life of the lubricating base oils (II) and (V) is preferably 350 min or more, more preferably 360 min or more, and further preferably 370 min or more. The RBOT life of the lubricating base oils (III) and (VI) is preferably 400 min or more, more preferably 410 min or more, and further preferably 420 min or more. When the RBOT life is less than the lower limit, the viscosity-temperature characteristics and thermal / oxidative stability of the lubricating base oil tend to decrease. Further, when an additive is blended in the lubricating base oil, The effectiveness of the additive tends to decrease.

  The RBOT life as used herein refers to a composition in which 0.2% by mass of a phenolic antioxidant (2,6-di-tert-butyl-p-cresol; DBPC) is added to a lubricating base oil. It means the RBOT value measured according to JIS K 2514-1996.

  In the lubricating oil composition for an internal combustion engine of the present invention, the lubricating base oil according to the present invention may be used alone, and the lubricating base oil according to the present invention is one or two of the other base oils. You may use together with a seed or more. When the lubricating base oil according to the present invention is used in combination with another base oil, the ratio of the lubricating base oil according to the present invention in the mixed base oil is preferably 30% by mass or more. 50% by mass or more is more preferable, and 70% by mass or more is still more preferable.

Although it does not restrict | limit especially as another base oil used together with the lubricating base oil concerning this invention, As a mineral oil type | system | group base oil, solvent refined mineral oil whose kinematic viscosity in 100 degreeC is 1-100 mm < ² > / s, for example, hydrogen Examples include hydrocracked mineral oil, hydrorefined mineral oil, and solvent dewaxing base oil.

  Synthetic base oils include poly α-olefins or hydrides thereof, isobutene oligomers or hydrides thereof, isoparaffins, alkylbenzenes, alkylnaphthalenes, diesters (ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridec Decyl adipate, di-2-ethylhexyl sebacate, etc.), polyol ester (trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol 2-ethylhexanoate, pentaerythritol pelargonate, etc.), polyoxyalkylene glycol, dialkyl Examples thereof include diphenyl ether and polyphenyl ether, and among them, poly α-olefin is preferable. As the poly α-olefin, typically, an oligomer or co-oligomer (1-octene oligomer, decene oligomer, ethylene-propylene co-oligomer, etc.) having 2 to 32 carbon atoms, preferably 6 to 16 carbon atoms, and those. Of the hydrides.

  The production method of the poly-α-olefin is not particularly limited. For example, Friedel-Crafts catalyst containing a complex of aluminum trichloride or boron trifluoride with water, alcohol (ethanol, propanol, butanol, etc.), carboxylic acid or ester. And a method of polymerizing α-olefin in the presence of a polymerization catalyst such as

  Moreover, the lubricating oil composition for internal combustion engines of this invention contains the ashless antioxidant which does not contain sulfur as a structural element as (A) component. As the component (A), a phenol-based or amine-based ashless antioxidant that does not contain sulfur as a constituent element is suitable.

  Specific examples of the phenol-based ashless antioxidant that does not contain sulfur as a constituent element include 4,4′-methylenebis (2,6-di-tert-butylphenol), 4,4′-bis (2 , 6-di-tert-butylphenol), 4,4'-bis (2-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2 ' -Methylenebis (4-methyl-6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 4,4'-isopropylidenebis (2,6-di-tert-butylphenol) ), 2,2′-methylenebis (4-methyl-6-nonylphenol), 2,2′-isobutylidenebis (4,6-dimethylphenol) 2,2'-methylenebis (4-methyl-6-cyclohexylphenol), 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-α-dimethylamino-p-cresol, 2,6-di-tert-butyl-4 (N, N′-dimethylaminomethyl) Phenol), octyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tridecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythrityl Tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3 -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, octyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, octyl-3- (3-methyl- 5-tert-butyl-4-hydroxyphenyl) propionate, and mixtures thereof. Among these, hydroxyphenyl group-substituted ester-based antioxidant (octyl-3- (3,5-di-tert-butyl-4-hydroxy), which is an ester of a hydroxyphenyl group-substituted fatty acid and an alcohol having 4 to 12 carbon atoms. Phenyl) propionate, octyl-3- (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, etc.) and bisphenol antioxidants are preferred, and hydroxyphenyl group-substituted ester antioxidants are more preferred. A phenol compound having a molecular weight of 240 or more is preferable because it has a high decomposition temperature and exhibits its effect even under higher temperature conditions.

  Specific examples of amine-based ashless antioxidants that do not contain sulfur as a constituent element include phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, alkyldiphenylamine, dialkyldiphenylamine, N, N′-diphenyl- p-Phenylenediamine and mixtures thereof are mentioned. As the alkyl group possessed by these amine-based ashless antioxidants, a linear or branched alkyl group having 1 to 20 carbon atoms is preferable, and a linear or branched alkyl group having 4 to 12 carbon atoms is more preferable. .

  The content of the component (A) in the present invention is not particularly limited, but is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.5% by mass or more based on the total amount of the composition. Especially preferably, it is 1.0 mass% or more, Preferably it is 5 mass% or less, More preferably, it is 3 mass% or less, Most preferably, it is 2 mass% or less. When the content is less than 0.01% by mass, the heat / oxidation stability of the lubricating oil composition becomes insufficient, and in particular, it tends to be impossible to maintain excellent cleanliness over a long period of time. On the other hand, when content of (A) component exceeds 5 mass%, it exists in the tendency for the storage stability of a lubricating oil composition to fall.

  In the present invention, as component (A), 0.4 to 2% by mass of a phenol-based ashless antioxidant and 0.4 to 2% by mass of an amine-based ashless antioxidant are used in combination based on the total amount of the composition. Alternatively, it is particularly preferable to use 0.5 to 2% by mass, more preferably 0.6 to 1.5% by mass of an amine-based antioxidant alone, thereby maintaining excellent cleanliness over a long period of time. be able to.

  The lubricating oil composition for an internal combustion engine of the present invention has at least one selected from (B-1) an ashless antioxidant containing sulfur as a constituent element and (B-2) an organic molybdenum compound as the component (B). Contains seeds.

  (B-1) Ashless antioxidants containing sulfur as a constituent element include sulfurized fats and oils, dihydrocarbyl polysulfides, dithiocarbamates, thiadiazoles, and phenolic ashless antioxidants containing sulfur as a constituent element. Is preferred.

  Examples of sulfurized fats and oils include sulfurized lard, sulfurized rapeseed oil, sulfurized castor oil, sulfurized soybean oil, and sulfurized rice bran oil; disulfide fatty acids such as sulfurized oleic acid; and sulfurized esters such as methyl sulfide oleate. .

Examples of the sulfurized olefin include compounds represented by the following general formula (4).
R ¹¹ -S _x -R ¹² (4)

In the general formula (4), R ¹¹ represents an alkenyl group having 2 to 15 carbon atoms, R ¹² represents an alkyl group or alkenyl group having 2 to 15 carbon atoms, and x represents an integer of 1 to 8. ]
The compound represented by the general formula (4) can be obtained by reacting an olefin having 2 to 15 carbon atoms or a dimer or tetramer thereof with a sulfurizing agent such as sulfur or sulfur chloride. As the olefin, for example, propylene, isobutene, diisobutene and the like are preferably used.

Dihydrocarbyl polysulfide is a compound represented by the following general formula (5).
R ¹³ -S _y -R ¹⁴ (5)

In General Formula (5), R ¹³ and R ¹⁴ are each independently an alkyl group having 1 to 20 carbon atoms (including a cycloalkyl group), an aryl group having 6 to 20 carbon atoms, and an aryl having 7 to 20 carbon atoms. Represents an alkyl group, which may be the same or different from each other, and y represents an integer of 2 to 8;

Specific examples of R ¹³ and R ¹⁴ include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, and various pentyl groups. Groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various dodecyl groups, cyclohexyl groups, phenyl groups, naphthyl groups, tolyl groups, xylyl groups, benzyl groups, and phenethyl groups. be able to.

  Specific examples of preferred dihydrocarbyl polysulfides include dibenzyl polysulfide, di-tert-nonyl polysulfide, didodecyl polysulfide, di-tert-butyl polysulfide, dioctyl polysulfide, diphenyl polysulfide, and dicyclohexyl polysulfide. It is done.

  Specific examples of dithiocarbamates include compounds represented by the following general formula (6) or (7).

In the general formulas (6) and (7), R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ , R ¹⁹ and R ²⁰ each independently represent a hydrocarbon group having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms. R ²¹ represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, preferably a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, e represents an integer of 0 to 4, and f represents an integer of 0 to 6. .

  Examples of the hydrocarbon group having 1 to 30 carbon atoms include an alkyl group, a cycloalkyl group, an alkylcycloalkyl group, an alkenyl group, an aryl group, an alkylaryl group, and an arylalkyl group.

  Examples of the thiadiazoles include a 1,3,4-thiadiazole compound represented by the following general formula (8), a 1,2,4-thiadiazole compound represented by the general formula (9), and a general formula (10). Mention may be made of 1,4,5-thiadiazole compounds.

In the general formulas (8) to (10), R ²² , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ and R ²⁷ may be the same or different, and each independently represents a hydrogen atom or 1 to 30 carbon atoms. And g, h, i, j, k, and l each independently represent an integer of 0 to 8.

  Examples of the hydrocarbon group having 1 to 30 carbon atoms include an alkyl group, a cycloalkyl group, an alkylcycloalkyl group, an alkenyl group, an aryl group, an alkylaryl group, and an arylalkyl group.

  Examples of the phenol-based ashless antioxidant containing sulfur as a constituent element include 4,4′-thiobis (2-methyl-6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert). -Butylphenol), 2,2′-thiobis (4-methyl-6-tert-butylphenol), bis (3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide, bis (3,5-di-tert) -Butyl-4-hydroxybenzyl) sulfide, 2,2′-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and the like.

  Among the above components (B-1), dihydrocarbyl polysulfide, dithiocarbamates and thiadiazoles are preferably used from the viewpoint that more excellent thermal / oxidative stability can be obtained.

  When the ashless antioxidant containing (B-1) sulfur as a constituent element is used as the component (B) in the present invention, the content is not particularly limited, but preferably in terms of elemental sulfur based on the total amount of the composition. Is 0.001% by mass or more, more preferably 0.005% by mass or more, still more preferably 0.01% by mass or more, and preferably 0.2% by mass or less, more preferably 0.1% by mass or less. Especially preferably, it is 0.04 mass% or less. When the content is less than the lower limit, the thermal and oxidation stability of the lubricating oil composition becomes insufficient, and in particular, it tends to be impossible to maintain excellent cleanliness over a long period of time. On the other hand, when the above upper limit is exceeded, the adverse effect on the exhaust gas purification device due to the high sulfur content of the lubricating oil composition tends to increase.

  The (B-2) organic molybdenum compound as the component (B) includes (B-2-1) an organic molybdenum compound containing sulfur as a constituent element, and (B-2-2) sulfur as a constituent element. Both organomolybdenum compounds are included.

  (B-2-1) Examples of the organic molybdenum compound containing sulfur as a constituent element include organic molybdenum complexes such as molybdenum dithiophosphate and molybdenum dithiocarbamate.

  Specific examples of molybdenum dithiophosphate include compounds represented by the following general formula (11).

In the general formula ^{(11), R 28, R} 29, R 30 and ^{R 31} may be different from each other in the same, having 2 to 30 carbon atoms, preferably 5 to 18 carbon atoms, more preferably 5 carbon atoms A hydrocarbon group such as an alkyl group having ˜12 or a (alkyl) aryl group having 6 to 18 carbon atoms, preferably 10 to 15 carbon atoms. Y ¹ , Y ² , Y ³ and Y ⁴ each represents a sulfur atom or an oxygen atom.

  Preferred examples of the alkyl group include ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, A hexadecyl group, a heptadecyl group, an octadecyl group, etc. are mentioned, These may be a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group, and may be linear or branched.

  Preferred examples of (alkyl) aryl groups include phenyl, tolyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, octylphenyl, nonylphenyl, decylphenyl, Examples thereof include a decylphenyl group and a dodecylphenyl group, and the alkyl group may be a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group, and may be linear or branched. Further, these (alkyl) aryl groups include all substituted isomers in which the substitution position of the alkyl group to the aryl group is different.

  Specific examples of preferred molybdenum dithiophosphates include molybdenum sulfide diethyldithiophosphate, molybdenum sulfide dipropyldithiophosphate, molybdenum dibutyldithiophosphate, molybdenum dipentyldithiophosphate, molybdenum dihexyldithiophosphate, molybdenum dioctyldithiophosphate, molybdenum disulfide. Decyl dithiophosphate, sulfurized molybdenum didodecyl dithiophosphate, molybdenum di (butylphenyl) dithiophosphate, molybdenum di (nonylphenyl) dithiophosphate, sulfurized oxymolybdenum diethyldithiophosphate, sulfurized oxymolybdenum dipropyldithiophosphate, sulfurized oxymolybdenum dibutyldithiophosphate, sulfurized Oki Molybdenum dipentyldithiophosphate, sulfurized oxymolybdenum dihexyldithiophosphate, sulfurized oxymolybdenum dioctyldithiophosphate, sulfurized oxymolybdenum didecyldithiophosphate, sulfurized oxymolybdenum didodecyldithiophosphate, sulfurized oxymolybdenum di (butylphenyl) dithiophosphate, sulfurized oxymolybdenum di (nonylphenyl) Examples include dithiophosphate (the alkyl group may be linear or branched, and the bonding position of the alkyl group of the alkylphenyl group is arbitrary), and mixtures thereof. As these molybdenum dithiophosphates, compounds having hydrocarbon groups having different carbon numbers and / or structures in one molecule can also be preferably used.

  As the molybdenum dithiocarbamate, specifically, for example, a compound represented by the following general formula (12) can be used.

In the general formula ^{(12), R 32, R} 33, R 34 and ^{R 35} may be the same as or different from each other, from 2 to 24 carbon atoms, preferably an alkyl group having 4 to 13 carbon atoms, or carbon atoms A hydrocarbon group such as an (alkyl) aryl group having 6 to 24, preferably 10 to 15 carbon atoms is shown. Y ⁵ , Y ⁶ , Y ⁷ and Y ⁸ each represent a sulfur atom or an oxygen atom.

  Preferred examples of the alkyl group include ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, A hexadecyl group, a heptadecyl group, an octadecyl group, etc. are mentioned, These may be a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group, and may be linear or branched.

  Preferred examples of (alkyl) aryl groups include phenyl, tolyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, octylphenyl, nonylphenyl, decylphenyl, Examples thereof include a decylphenyl group and a dodecylphenyl group, and the alkyl group may be a primary alkyl group, a secondary alkyl group, or a tertiary alkyl group, and may be linear or branched. Further, these (alkyl) aryl groups include all substituted isomers in which the substitution position of the alkyl group to the aryl group is different. Examples of molybdenum dithiocarbamate other than the above structure include those having a structure in which a dithiocarbamate group is coordinated to thio or polythio-trinuclear molybdenum as disclosed in WO98 / 26030 or WO99 / 31113.

  Specific examples of preferred molybdenum dithiocarbamates include molybdenum sulfide diethyldithiocarbamate, molybdenum dipropyldithiocarbamate, molybdenum dibutyldithiocarbamate, molybdenum dipentyldithiocarbamate, molybdenum dihexyldithiocarbamate, molybdenum dihexyldithiocarbamate, molybdenum dioctyldithiocarbamate, and molybdenum disulfide. Decyl dithiocarbamate, sulfurized molybdenum didodecyl dithiocarbamate, molybdenum di (butylphenyl) dithiocarbamate, molybdenum di (nonylphenyl) dithiocarbamate, sulfurized oxymolybdenum diethyldithiocarbamate, sulfurized oxymolybdenum dipropyldithiocarbamate, sulfurized oxymolybdenum dibutyldithiocarbamate Oki Molybdenum dipentyldithiocarbamate, sulfurized oxymolybdenum dihexyldithiocarbamate, sulfurized oxymolybdenum dioctyldithiocarbamate, sulfurized oxymolybdenum didecyldithiocarbamate, sulfurized oxymolybdenum didodecyldithiocarbamate, sulfurized oxymolybdenum di (butylphenyl) dithiocarbamate, sulfurized oxymolybdenum di (nonylphenyl) Examples thereof include dithiocarbamate (the alkyl group may be linear or branched, and the bonding position of the alkyl group of the alkylphenyl group is arbitrary), and mixtures thereof. As these molybdenum dithiocarbamates, compounds having hydrocarbon groups having different carbon numbers and / or structures in one molecule can also be preferably used.

  Other organic molybdenum complexes containing sulfur include molybdenum compounds (for example, molybdenum oxide such as molybdenum dioxide and molybdenum trioxide, orthomolybdic acid, paramolybdic acid, molybdic acid such as (poly) sulfurized molybdic acid, Molybdate such as metal salts of molybdic acid, ammonium salts, molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, molybdenum sulfide such as polysulfide molybdenum, metal sulfide or amine salt of molybdenum sulfide, sulfurized molybdenum acid, chloride Molybdenum halides such as molybdenum) and sulfur-containing organic compounds (eg, alkyl (thio) xanthate, thiadiazole, mercaptothiadiazole, thiocarbonate, tetrahydrocarbylthiuram disulfide, bis (di (thio) hydrocarb) (Ludithiophosphonate) disulfide, organic (poly) sulfide, sulfurized ester, etc.) or other organic compounds, etc., or sulfur-containing molybdenum compounds such as molybdenum sulfide and sulfurized molybdic acid, and alkenyl succinimide complexes, etc. Can be mentioned.

  When an organic molybdenum compound containing (B-2-1) sulfur as a constituent element is used as the component (B) in the present invention, it is preferable because a friction reducing effect can be obtained in addition to the effect of improving thermal and oxidation stability. Of these, molybdenum dithiocarbamate is particularly preferred.

  (B-2-2) Specific examples of the organic molybdenum compound not containing sulfur as a constituent element include molybdenum-amine complexes, molybdenum-succinimide complexes, molybdenum salts of organic acids, molybdenum salts of alcohols, and the like. Among them, a molybdenum-amine complex, a molybdenum salt of an organic acid, and a molybdenum salt of an alcohol are preferable.

Examples of the molybdenum compound constituting the molybdenum-amine complex include molybdenum trioxide or a hydrate thereof (MoO ₃ · nH ₂ O), molybdic acid (H ₂ MoO ₄ ), and an alkali metal molybdate (M ₂ MoO ₄ ; M Represents an alkali metal), ammonium molybdate ((NH ₄ ) 2 MoO ₄ or (NH ₄ ) ₆ [Mo ₇ O ₂₄ ] · 4H ₂ O), MoCl ₅ , MoOCl ₄ , MoO ₂ Cl ₂ , MoO ₂ Br ₂ And molybdenum compounds containing no sulfur such as Mo ₂ O ₃ Cl ₆ . Among these molybdenum compounds, hexavalent molybdenum compounds are preferable from the viewpoint of the yield of the molybdenum-amine complex. Further, from the viewpoint of availability, among the hexavalent molybdenum compounds, molybdenum trioxide or a hydrate thereof, molybdic acid, alkali metal molybdate, and ammonium molybdate are preferable.

  Moreover, the nitrogen compound constituting the molybdenum-amine complex is not particularly limited, and examples thereof include ammonia, monoamine, diamine, and polyamine. More specifically, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine , Hexadecylamine, heptadecylamine, octadecylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, diundecylamine, didodecylamine, ditridecylamine Decylamine, ditetradecylamine, dipentadecylamine, dihexadecylamine, diheptadecylamine, dioctadecylamine, methyl ethyl Alkylamines having an alkyl group having 1 to 30 carbon atoms such as amine, methylpropylamine, methylbutylamine, ethylpropylamine, ethylbutylamine, and propylbutylamine (these alkyl groups may be linear or branched); Alkenyl amines having 2 to 30 carbon atoms such as ethenylamine, propenylamine, butenylamine, octenylamine, and oleylamine (these alkenyl groups may be linear or branched); methanolamine, ethanolamine, propanolamine , Butanolamine, pentanolamine, hexanolamine, heptanolamine, octanolamine, nonanolamine, methanol ethanolamine, methanol propanolamine, methanol butanol amine Alkanolamines having 1 to 30 carbon atoms such as ethanolpropanolamine, ethanolbutanolamine, and propanolbutanolamine (these alkanol groups may be linear or branched); methylenediamine, ethylenediamine, Alkylene diamines having 1-30 carbon atoms such as propylene diamine and butylene diamine; polyamines such as diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine; undecyl diethylamine, undecyl diethanolamine, dodecyl dipropanol Amine, oleyl diethanolamine, oleyl propylene diamine, stearyl tetraethylene pentamine, etc. Examples thereof include compounds having an alkyl group or alkenyl group having 8 to 20 carbon atoms in the amine and heterocyclic compounds such as N-hydroxyethyloleylimidazoline; alkylene oxide adducts of these compounds; and mixtures thereof. Of these, primary amines, secondary amines, and alkanolamines are preferred.

  Carbon number of the hydrocarbon group which the amine compound which comprises a molybdenum-amine complex has becomes like this. Preferably it is 4 or more, More preferably, it is 4-30, Most preferably, it is 8-18. When the number of carbon atoms of the hydrocarbon group of the amine compound is less than 4, the solubility tends to deteriorate. Moreover, by setting the number of carbon atoms in the amine compound to 30 or less, the molybdenum pigment in the molybdenum-amine complex can be rapidly increased, and the effects of the present invention can be further enhanced with a small amount of compounding.

  The molybdenum-succinimide complex is a complex of a sulfur-free molybdenum compound as exemplified in the description of the molybdenum-amine complex and a succinimide having an alkyl group or alkenyl group having 4 or more carbon atoms. Is mentioned. As the succinimide, succinimide having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or a derivative thereof, or an alkyl group having 4 to 39 carbon atoms, preferably 8 to 18 carbon atoms. Or the succinimide etc. which have an alkenyl group are mentioned. If the alkyl group or alkenyl group in the succinimide has less than 4 carbon atoms, the solubility tends to deteriorate. A succinimide having an alkyl group or an alkenyl group having more than 30 carbon atoms and not more than 400 carbon atoms can also be used. By setting the alkyl group or alkenyl group to 30 or less carbon atoms, molybdenum-succinimide is obtained. The molybdenum content in the complex can be relatively increased, and the effects of the present invention can be further enhanced with a small amount of compounding.

  Examples of the molybdenum salt of an organic acid include a salt of a molybdenum base such as molybdenum oxide or molybdenum hydroxide, molybdenum carbonate or molybdenum chloride exemplified in the description of the molybdenum-amine complex and an organic acid. It is done. As an organic acid, the phosphorus compound and carboxylic acid which are represented with the following general formula (P-1) or (P-2) are preferable.

［式（Ｐ−１）中、Ｒ^５７は炭素数１〜３０の炭化水素基を示し、Ｒ^５８及びＲ^５９は同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜３０の炭化水素基を示し、ｎは０又は１を示す。］

[In Formula (P-1), R ⁵⁷ represents a hydrocarbon group having 1 to 30 carbon atoms, and R ⁵⁸ and R ⁵⁹ may be the same or different, and each represents a hydrogen atom or a hydrocarbon having 1 to 30 carbon atoms. Represents a group, and n represents 0 or 1. ]

［式（Ｐ−２）中、Ｒ^６０、Ｒ^６１及びＲ^６２は同一でも異なっていてもよく、それぞれ水素原子又は炭素数１〜３０の炭化水素基を示し、ｎは０又は１を示す。］

[In Formula (P-2), R ⁶⁰ , R ⁶¹ and R ⁶² may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, and n represents 0 or 1. ]

  Moreover, as carboxylic acid which comprises the molybdenum salt of carboxylic acid, either a monobasic acid or a polybasic acid may be sufficient.

  As the monobasic acid, a fatty acid having 2 to 30 carbon atoms, preferably 4 to 24 carbon atoms, is used. The fatty acid may be linear or branched, and may be saturated or unsaturated. . Specifically, for example, acetic acid, propionic acid, linear or branched butanoic acid, linear or branched pentanoic acid, linear or branched hexanoic acid, linear or branched heptane Acid, linear or branched octanoic acid, linear or branched nonanoic acid, linear or branched decanoic acid, linear or branched undecanoic acid, linear or branched dodecane Acid, linear or branched tridecanoic acid, linear or branched tetradecanoic acid, linear or branched pentadecanoic acid, linear or branched hexadecanoic acid, linear or branched heptadecane Acid, linear or branched octadecanoic acid, linear or branched hydroxyoctadecanoic acid, linear or branched nonadecanoic acid, linear or branched icosanoic acid, linear or branched Henicosanoic acid, linear or branched Saturated fatty acids such as cosanoic acid, linear or branched tricosanoic acid, linear or branched tetracosanoic acid, acrylic acid, linear or branched butenoic acid, linear or branched pentenoic acid, Linear or branched hexenoic acid, linear or branched heptenoic acid, linear or branched octenoic acid, linear or branched nonenoic acid, linear or branched decenoic acid, Linear or branched undecenoic acid, linear or branched dodecenoic acid, linear or branched tridecenoic acid, linear or branched tetradecenoic acid, linear or branched pentadecenoic acid, Linear or branched hexadecenoic acid, linear or branched heptadecenoic acid, linear or branched octadecenoic acid, linear or branched hydroxyoctadecenoic acid, linear or branched nonadecene Acid, linear or branched Unsaturated fatty acids such as cocenoic acid, linear or branched heicosenoic acid, linear or branched docosenoic acid, linear or branched tricosenoic acid, linear or branched tetracosenoic acid, and the like And the like.

  Moreover, as a monobasic acid, in addition to the above fatty acid, a monocyclic or polycyclic carboxylic acid (which may have a hydroxyl group) may be used, and the carbon number thereof is preferably 4 to 30, and more preferably. Is 7-30. The monocyclic or polycyclic carboxylic acid is an aromatic carboxylic acid having 0 to 3, preferably 1 to 2 linear or branched alkyl groups having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms. Or cycloalkyl carboxylic acid etc. are mentioned, More specifically, (alkyl) benzene carboxylic acid, (alkyl) naphthalene carboxylic acid, (alkyl) cycloalkyl carboxylic acid, etc. can be illustrated. Preferable examples of the monocyclic or polycyclic carboxylic acid include benzoic acid, salicylic acid, alkylbenzoic acid, alkylsalicylic acid, and cyclohexanecarboxylic acid.

  Examples of polybasic acids include dibasic acids, tribasic acids, and tetrabasic acids. The polybasic acid may be a chain polybasic acid or a cyclic polybasic acid. Further, in the case of a chain polybasic acid, it may be either linear or branched, and may be either saturated or unsaturated. As the chain polybasic acid, a chain dibasic acid having 2 to 16 carbon atoms is preferable. Specifically, for example, ethanedioic acid, propanedioic acid, linear or branched butanedioic acid, linear Or branched pentanedioic acid, linear or branched hexanedioic acid, linear or branched heptanedioic acid, linear or branched octanedioic acid, linear or branched nonane diacid Acid, linear or branched decanedioic acid, linear or branched undecanedioic acid, linear or branched dodecanedioic acid, linear or branched tridecanedioic acid, linear or Branched tetradecanedioic acid, linear or branched heptadecanedioic acid, linear or branched hexadecanedioic acid, linear or branched hexenedioic acid, linear or branched heptenedioic acid Linear or branched octene diacid, linear or branched nonene diacid, linear or branched Branched decenedioic acid, linear or branched undecenedioic acid, linear or branched dodecenedioic acid, linear or branched tridecenedioic acid, linear or branched tetradecenedioic acid And linear or branched heptadecene diacid, linear or branched hexadecene diacid, alkenyl succinic acid, and mixtures thereof. As the cyclic polybasic acid, 1,2-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid alicyclic dicarboxylic acid, phthalic acid or other aromatic dicarboxylic acid, trimellitic acid or other aromatic Examples thereof include aromatic tetracarboxylic acids such as tricarboxylic acid and pyromellitic acid.

  Examples of the molybdenum salt of the alcohol include a salt of a molybdenum compound not containing sulfur as exemplified in the description of the molybdenum-amine complex with an alcohol. The alcohol may be a monohydric alcohol, a polyhydric alcohol, Any of a partial ester or partial ester compound of a monohydric alcohol, a nitrogen compound having a hydroxyl group (alkanolamine, etc.), etc. may be used. Molybdic acid is a strong acid and forms an ester by reaction with alcohol. The ester of molybdic acid and alcohol is also included in the molybdenum salt of alcohol in the present invention.

  As the monohydric alcohol, those having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms are usually used. Such alcohols may be linear or branched, and saturated. Or may be unsaturated. Specific examples of the alcohol having 1 to 24 carbon atoms include methanol, ethanol, linear or branched propanol, linear or branched butanol, linear or branched pentanol, and linear Linear or branched hexanol, linear or branched heptanol, linear or branched octanol, linear or branched nonanol, linear or branched decanol, linear or branched Undecanol, linear or branched dodecanol, linear or branched tridecanol, linear or branched tetradecanol, linear or branched pentadecanol, linear or branched hexadecane Decanol, linear or branched heptadecanol, linear or branched octadecanol, linear or branched nonadecanol, linear or branched icosa Lumpur, linear or branched Hen'ikosanoru, linear or branched Torikosanoru, such as linear or branched tetracosanol, and mixtures thereof.

  Moreover, as a polyhydric alcohol, the thing of 2-10 valence is preferable, Preferably it is 2-6 valence. Specific examples of the 2 to 10 polyhydric alcohol include, for example, ethylene glycol, diethylene glycol, polyethylene glycol (3 to 15 mer of ethylene glycol), propylene glycol, dipropylene glycol, and polypropylene glycol (3 to 15 of propylene glycol). Monomer), 1,3-propanediol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 2-methyl-1,2-propanediol, 2-methyl-1,3 -Dihydric alcohols such as propanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, neopentylglycol; glycerin, polyglycerin (glycerin 2- Octamers such as diglycerin, triglyceride Phosphorus, tetraglycerin, etc.), trimethylolalkanes (trimethylolethane, trimethylolpropane, trimethylolbutane, etc.) and their 2- to 8-mer, pentaerythritol and their 2- to 4-mer, 1,2,4- Butanetriol, 1,3,5-pentanetriol, 1,2,6-hexanetriol, 1,2,3,4-butanetetrol, sorbitol, sorbitan, sorbitol glycerin condensate, adonitol, arabitol, xylitol, mannitol, etc. Polysaccharides of xylose, arabinose, ribose, rhamnose, glucose, fructose, galactose, mannose, sorbose, cellobiose, maltose, isomaltose, trehalose, sucrose, sugars, and mixtures thereof That.

  Examples of the partial ester of the polyhydric alcohol include compounds in which a part of the hydroxyl group of the polyhydric alcohol exemplified in the description of the polyhydric alcohol has been hydrocarbyl esterified, among which glycerin monooleate and glycerin dioleate. Sorbitan monooleate, sorbitandiolate, pentaerythritol monooleate, polyethylene glycol monooleate, and polyglycerin monooleate are preferred.

  Moreover, as the partial ether of the polyhydric alcohol, an ether bond is formed by condensation of polyhydric alcohols, a compound in which a part of the hydroxyl groups of the polyhydric alcohol exemplified in the description of the polyhydric alcohol is hydrocarbyl etherified. Compounds (such as sorbitan condensate) and the like, among which 3-octadecyloxy-1,2-propanediol, 3-octadecenyloxy-1,2-propanediol, polyethylene glycol alkyl ether and the like are preferable.

  Examples of the nitrogen compound having a hydroxyl group include alkanolamines exemplified in the description of the molybdenum-amine complex, and alkanolamides (diethanolamide, etc.) in which the amino group of the alkanol is amidated. Diethanolamine, polyethylene glycol stearylamine, polyethylene glycol dioleylamine, hydroxyethyl laurylamine, oleic acid diethanolamide and the like are preferable.

  When an organic molybdenum compound not containing (B-2-2) sulfur as a constituent element is used as the component (B) in the present invention, the high-temperature cleanliness and base number retention of the lubricating oil composition can be improved, It is preferable in that the initial friction reducing effect can be maintained for a long time, and a molybdenum-amine complex is particularly preferable.

  In the present invention, (B-2-1) an organic molybdenum compound containing sulfur as a constituent element and (B-2-2) an organic molybdenum compound not containing sulfur as a constituent element may be used in combination.

  When (B-2) an organomolybdenum compound is used as the component (B) in the present invention, the content thereof is not particularly limited, but is preferably 0.001% by mass or more in terms of molybdenum element based on the total amount of the composition. More preferably, it is 0.005 mass% or more, More preferably, it is 0.01 mass% or more, Preferably it is 0.2 mass% or less, More preferably, it is 0.1 mass% or less, Especially preferably, it is 0.04 mass % Or less. When the content is less than 0.001% by mass, the thermal and oxidation stability of the lubricating oil composition becomes insufficient, and in particular, it tends to be impossible to maintain excellent cleanliness over a long period of time. On the other hand, when content of (B-1) component exceeds 0.2 mass%, the effect corresponding to content is not acquired, and it exists in the tendency for the storage stability of a lubricating oil composition to fall.

  The lubricating oil composition for an internal combustion engine of the present invention may be composed only of the above-described lubricating base oil and the components (A) and (B), but if necessary, in order to further improve its performance. In addition, various additives shown below may be further contained.

  The lubricating oil composition for an internal combustion engine of the present invention preferably further contains an antiwear agent from the viewpoint of further improving the wear resistance. As such extreme pressure agents, phosphorus extreme pressure agents, phosphorus-sulfur extreme pressure agents and the like are preferably used.

  Phosphorus extreme pressure agents include phosphoric acid, phosphorous acid, phosphoric acid esters (including phosphoric acid monoesters, phosphoric acid diesters and phosphoric acid triesters), phosphorous acid esters (phosphorous acid monoesters) Esters, phosphite diesters and phosphite triesters), and salts thereof (amine salts or metal salts). As phosphoric acid esters and phosphorous acid esters, those having a hydrocarbon group usually having 2 to 30 carbon atoms, preferably 3 to 20 carbon atoms are used.

Phosphorus-sulfur extreme pressure agents include thiophosphoric acid, thiophosphorous acid, thiophosphoric acid esters (including thiophosphoric acid monoesters, thiophosphoric acid diesters, thiophosphoric acid triesters), and thiophosphorous acid esters. (Including thiophosphite monoesters, thiophosphite diesters, thiophosphite triesters), salts thereof, and zinc dithiophosphate. As the thiophosphates and thiophosphites, those having a hydrocarbon group usually having 2 to 30 carbon atoms, preferably 3 to 20 carbon atoms are used. The content of the extreme pressure agent is not particularly limited, but is preferably 0.01 to 5% by mass, more preferably 0.1 to 3% by mass, based on the total amount of the composition.

  In the present invention, zinc dithiophosphate is particularly preferable among the above extreme pressure agents. Examples of zinc dithiophosphate include compounds represented by the following general formula (13).

R ³⁶ , R ³⁷ , R ³⁸ and R ³⁹ in the general formula (13) each independently represent a hydrocarbon group having 1 to 24 carbon atoms. Examples of these hydrocarbon groups include linear or branched alkyl groups having 1 to 24 carbon atoms, linear or branched alkenyl groups having 3 to 24 carbon atoms, and cycloalkyl groups having 5 to 13 carbon atoms. Or a linear or branched alkylcycloalkyl group, an aryl group having 6 to 18 carbon atoms, or a linear or branched alkylaryl group, an arylalkyl group having 7 to 19 carbon atoms, or the like. It is desirable to be. The alkyl group or alkenyl group may be any of primary, secondary, and tertiary.

Specific examples of R ³⁶ , R ³⁷ , R ³⁸ and R ³⁹ include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, Undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group, tricosyl group, tetracosyl group, etc. Propenyl, butenyl, butadienyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl and oleyl Etc. Alkenyl groups such as decenyl group, nonadecenyl group, icocenyl group, heicosenyl group, dococenyl group, tricocenyl group and tetracocenyl group, cycloalkyl groups such as cyclopentyl group, cyclohexyl group and cycloheptyl group, methylcyclopentyl group, dimethylcyclopentyl group, Ethylcyclopentyl group, propylcyclopentyl group, ethylmethylcyclopentyl group, trimethylcyclopentyl group, diethylcyclopentyl group, ethyldimethylcyclopentyl group, propylmethylcyclopentyl group, propylethylcyclopentyl group, di-propylcyclopentyl group, propylethylmethylcyclopentyl group, methylcyclohexyl Xyl group, dimethyl cyclohexyl group, ethyl cyclohexyl group, propyl cyclohexyl group, ethyl methyl group Rohexyl group, trimethylcyclohexyl group, diethylcyclohexyl group, ethyldimethylcyclohexyl group, propylmethylcyclohexyl group, propylethylcyclohexyl group, di-propylcyclohexyl group, propylethylmethylcyclohexyl group, methylcycloheptyl group, dimethyl Cycloheptyl group, ethylcycloheptyl group, propylcycloheptyl group, ethylmethylcycloheptyl group, trimethylcycloheptyl group, diethylcycloheptyl group, ethyldimethylcycloheptyl group, propylmethylcycloheptyl group, propylethylcycloheptyl group, di- Alkylcycloalkyl groups such as propylcycloheptyl group and propylethylmethylcycloheptyl group; aryl groups such as phenyl group and naphthyl group; tolyl group; Group, ethylphenyl group, propylphenyl group, ethylmethylphenyl group, trimethylphenyl group, butylphenyl group, propylmethylphenyl group, diethylphenyl group, ethyldimethylphenyl group, tetramethylphenyl group, pentylphenyl group, hexylphenyl group Alkylaryl groups such as heptylphenyl group, octylphenyl group, nonylphenyl group, decylphenyl group, undecylphenyl group and dodecylphenyl group, benzyl group, methylbenzyl group, dimethylbenzyl group, phenethyl group, methylphenethyl group and dimethyl group Examples thereof include arylalkyl groups such as phenethyl group. And so on. The hydrocarbon group includes all possible straight chain structures and branched structures, and also includes the position of the double bond of the alkenyl group, the position of bond of the alkyl group to the cycloalkyl group, and the alkyl group. The position of bonding of the aryl group to the aryl group and the position of bonding of the aryl group to the alkyl group are arbitrary.

  Preferred examples of the zinc dithiophosphate include, for example, zinc diisopropyldithiophosphate, zinc diisobutyldithiophosphate, zinc di-sec-butyldithiophosphate, zinc di-sec-pentyldithiophosphate, zinc di-n-hexyldithiophosphate. , Zinc di-sec-hexyldithiophosphate, zinc di-octyldithiophosphate, zinc di-2-ethylhexyldithiophosphate, zinc di-n-decyldithiophosphate, zinc di-n-dodecyldithiophosphate, zinc diisotridecyldithiophosphate , And mixtures of these arbitrary combinations.

The manufacturing method of the said zinc dithiophosphate is not specifically limited, It can manufacture by employ | adopting arbitrary conventional methods. Specifically, for example, alcohol or phenol having a hydrocarbon group corresponding to R ³⁶ , R ³⁷ , R ³⁸ and R ³⁹ in the above formula (13) is reacted with niline pentasulfide to obtain dithiophosphoric acid, It can be synthesized by neutralizing with zinc oxide. In addition, the structure of the said zinc dithiophosphate changes with raw material alcohol etc. to be used.

  Further, the content of the zinc dithiophosphate is not particularly limited, but from the viewpoint of suppressing catalyst poisoning of the exhaust gas purification apparatus, it is preferably 0.2% by mass or less in terms of phosphorus element based on the total amount of the composition. More preferably, it is 0.1 mass% or less, More preferably, it is 0.08 mass% or less, Most preferably, it is 0.06 mass% or less. Further, the content of zinc dithiophosphate is preferably 0.01% by mass in terms of phosphorus element, based on the total amount of the composition, from the viewpoint of the formation of a metal phosphate that exerts the effect of the antiwear additive. As mentioned above, More preferably, it is 0.02 mass% or more, More preferably, it is 0.04 mass% or more. When the content of zinc dithiophosphate is less than the lower limit, the effect of improving the wear resistance due to the addition tends to be insufficient.

  The lubricating oil composition for internal combustion engines of the present invention preferably further contains an ashless dispersant from the viewpoint of cleanliness and sludge dispersibility. Such ashless dispersants include alkenyl succinimides, alkyl succinimides and their derivatives derived from polyolefins. A typical succinimide is a polyalkylene polyamine containing an average of 4 to 10 (preferably 5 to 7) nitrogen atoms per molecule, and a succinic anhydride substituted with a high molecular weight alkenyl or alkyl group. It can obtain by reaction. The high molecular weight alkenyl group or alkyl group is preferably polybutene (polyisobutene) having a number average molecular weight of 700 to 5,000, and more preferably polybutene (polyisobutene) having a number average molecular weight of 900 to 3,000.

  Examples of the polybutenyl succinimide preferably used in the lubricating oil composition for an internal combustion engine of the present invention include compounds represented by the following general formula (14) or (15).

  PIB in the general formula (14) or (15) represents a polybutenyl group, and is obtained from polybutene obtained by polymerizing a high purity isobutene or a mixture of 1-butene and isobutene with a boron fluoride catalyst or an aluminum chloride catalyst. In the polybutene mixture, those having a vinylidene structure at the terminal are usually contained in an amount of 5 to 100 mol%. Further, n is an integer of 2 to 5, preferably 3 to 4 from the viewpoint of excellent sludge suppression effect.

  Although there is no restriction | limiting in particular as a manufacturing method of the succinimide represented by General formula (14) or (15), For example, what chlorinated the said polybutene, Preferably the said high purity isobutene is a boron fluoride type catalyst. Polymerized highly reactive polybutene (polyisobutene), more preferably polybutenyl succinic acid obtained by reacting polybutene from which chlorine and fluorine have been sufficiently removed with maleic anhydride at 100 to 200 ° C., is converted into diethylenetriamine, triethylenetetramine. It can be obtained by reacting with a polyamine such as tetraethylenepentamine or pentaethylenehexamine. In the case of producing bissuccinimide, the polybutenyl succinic acid may be reacted twice as much as the polyamine (molar ratio). In the case of producing monosuccinimide, the polybutenyl succinic acid and the polyamine are used. May be reacted in an equal amount (molar ratio). Among these, polybutenyl bissuccinimide is preferable from the viewpoint of excellent sludge dispersibility.

  The polybutene used in the above production method may contain a trace amount of fluorine and chlorine due to the catalyst in the production process. Therefore, the fluorine and chlorine content can be reduced by an appropriate method such as an adsorption method or sufficient water washing. It is preferable to use polybutene that has been sufficiently removed. The content of fluorine or chlorine is preferably 50 mass ppm or less, more preferably 10 mass ppm or less, still more preferably 5 mass ppm or less, and particularly preferably 1 mass ppm or less.

  In the step of obtaining polybutenyl succinic anhydride by reaction of polybutene and maleic anhydride, a chlorination method using chlorine is often applied conventionally. However, this method results in a large amount of chlorine (eg, about 2000 to 3000 ppm) remaining in the succinimide final product. On the other hand, in a method that does not use chlorine, for example, when the above highly reactive polybutene is used and / or in a thermal reaction method, chlorine remaining in the final product can be suppressed to an extremely low level (for example, 0 to 30 ppm). Therefore, in order to suppress the chlorine content in the lubricating oil composition to an amount in the range of 0 to 30 ppm by weight, the method using the highly reactive polybutene and / or the thermal reaction method is used without using the chlorination method. It is preferable to use the obtained polybutenyl succinic anhydride.

  Moreover, as a derivative | guide_body of polybutenyl succinimide, in addition to the compound represented by the said General formula (14) or (15), boron compounds, such as a boric acid, alcohol, an aldehyde, a ketone, alkylphenol, cyclic carbonate, organic It can be used as a so-called modified succinimide in which an oxygen-containing organic compound such as an acid is allowed to act to neutralize or amidate part or all of the remaining amino group and / or imino group. In particular, a boron-containing alkenyl (or alkyl) succinimide obtained by a reaction with a boron compound such as boric acid is advantageous in terms of thermal and oxidation stability.

  Examples of the boron compound that acts on the compound represented by the general formula (14) or (15) include boric acid, borates, and borate esters. Specific examples of boric acid include orthoboric acid, metaboric acid, and tetraboric acid. Examples of borates include alkali metal salts, alkaline earth metal salts or ammonium salts of boric acid, and more specifically, for example, lithium metaborate, lithium tetraborate, lithium pentaborate, perborate. Lithium borate such as lithium; sodium borate such as sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate; potassium metaborate, potassium tetraborate, Potassium borates such as potassium pentaborate, potassium hexaborate and potassium octaborate; calcium borates such as calcium metaborate, calcium diborate, tricalcium tetraborate, pentacalcium tetraborate and calcium hexaborate ; Magnesium metaborate, magnesium diborate, trimagnesium tetraborate, pentaborate Neshiumu, magnesium borate and magnesium hexaborate acid; and ammonium metaborate, ammonium tetraborate, ammonium pentaborate and ammonium borate such as ammonium eight borate. Examples of the boric acid ester include esters of boric acid and preferably an alkyl alcohol having 1 to 6 carbon atoms. More specifically, examples thereof include monomethyl borate, dimethyl borate, trimethyl borate, and boric acid. Examples include monoethyl, diethyl borate, triethyl borate, monopropyl borate, dipropyl borate, tripropyl borate, monobutyl borate, dibutyl borate, tributyl borate and the like. The succinimide derivative in which the boron compound is allowed to act is preferably used since it is excellent in heat resistance and oxidation stability.

  Specific examples of the oxygen-containing organic compound that acts on the compound represented by the general formula (14) or (15) include formic acid, acetic acid, glycolic acid, propionic acid, lactic acid, butyric acid, valeric acid, Carbon such as caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecyl acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, oleic acid, nonadecanoic acid, eicosanoic acid C1-C30 monocarboxylic acid, oxalic acid, phthalic acid, trimellitic acid, pyromellitic acid, etc., C2-C30 polycarboxylic acid or their anhydrides, ester compounds, C2-C6 Examples include alkylene oxide and hydroxy (poly) oxyalkylene carbonate. By allowing such an oxygen-containing organic compound to act, for example, part or all of the amino group or imino group in the compound represented by the general formula (14) or (15) is represented by the following general formula (16). Presumed to be a structure.

R ⁴⁰ in the general formula (16) is a hydrogen atom, an alkyl group having 1 to 24 carbon atoms, an alkenyl group having 1 to 24 carbon atoms, an alkoxy group having 1 to 24 carbon atoms, or —O— (R ⁴¹ O) _m. A hydroxy (poly) oxyalkylene group represented by H, wherein R ⁴¹ represents an alkylene group having 1 to 4 carbon atoms, and m represents an integer of 1 to 5; Among these, polybutenyl bissuccinimides mainly composed of those in which these oxygen-containing organic compounds are allowed to act on all amino groups or imino groups are preferably used since they are excellent in sludge dispersibility. Such a compound can be obtained, for example, by allowing (n-1) mol of an oxygen-containing organic compound to act on 1 mol of the compound of the formula (11). A succinimide derivative having such an oxygen-containing organic compound acted thereon is excellent in sludge dispersibility, and in particular, one having hydroxy (poly) oxyalkylene carbonate acted thereon is preferable.

  The weight average molecular weight of polybutenyl succinimide and / or a derivative thereof as an ashless dispersant used in the present invention is preferably 5000 or more, more preferably 6500 or more, still more preferably 7000 or more, and particularly preferably 8000 or more. is there. When the weight average molecular weight is less than 5,000, the molecular weight of the non-polar polybutenyl group is small and the sludge dispersibility is poor, and the amine portion of the polar group which may become an active site for oxidative degradation is relatively increased and oxidized. Since it is inferior in stability, it is considered that the effect of extending the life as in the present invention cannot be obtained. On the other hand, the weight average molecular weight of polybutenyl succinimide and / or a derivative thereof is preferably 20000 or less and particularly preferably 15000 or less from the viewpoint of preventing deterioration of low temperature viscosity characteristics. Here, the weight average molecular weight means that two columns of Tosoh GMHHR-M (7.8 mm ID × 30 cm) are used in series on a Waters 150-CALC / GPC apparatus, and the solvent is tetrahydrofuran, temperature. 23 ° C., flow rate of 1 mL / min, sample concentration of 1% by mass, sample injection amount of 75 μL, and weight average molecular weight in terms of polystyrene measured with a detector differential refractometer (RI).

  In the present invention, as the ashless dispersant, in addition to the succinimide and / or derivative thereof, alkyl or alkenyl polyamine, alkyl or alkenyl benzylamine, alkyl or alkenyl succinate, Mannich base and derivatives thereof are used. Can be used.

  The content of the ashless dispersant in the lubricating oil composition for an internal combustion engine of the present invention is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, in terms of nitrogen element, based on the total amount of the composition. More preferably, it is 0.05 mass% or more, Preferably it is 0.3 mass% or less, More preferably, it is 0.2 mass% or less, More preferably, it is 0.15 mass% or less. When the content of the ashless dispersant is less than the above lower limit value, a sufficient cleansing effect cannot be exhibited, while when the content exceeds the above upper limit value, the low temperature viscosity characteristics are deteriorated and the demulsibility is decreased. Since it deteriorates, it is not preferable respectively. In addition, when using a succinimide-based ashless dispersant having a weight average molecular weight of 6500 or more, the content is based on the total amount of the composition in terms of exhibiting sufficient sludge dispersibility and excellent low-temperature viscosity characteristics. It is preferable to set it as 0.005-0.05 mass% in conversion of nitrogen element, and it is more preferable to set it as 0.01-0.04 mass%.

  Further, when using a high molecular weight ashless dispersant, the content is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, in terms of nitrogen element, based on the total amount of the composition, Moreover, Preferably it is 0.1 mass% or less, More preferably, it is 0.05 mass% or less. When the content of the high molecular weight ashless dispersant is less than the above lower limit value, a sufficient cleansing effect cannot be exerted. On the other hand, when the content exceeds the above upper limit value, the low temperature viscosity characteristics are deteriorated and the resistance Since the emulsifying properties deteriorate, each is not preferable.

  Further, when using an ashless dispersant modified with a boron compound, the content is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, in terms of boron element, based on the total amount of the composition. More preferably, it is 0.02 mass% or more, preferably 0.2 mass% or less, more preferably 0.1 mass% or less. When the content of the ashless dispersant modified with a boron compound is less than the above lower limit value, a sufficient cleansing effect cannot be exhibited, while when the content exceeds the above upper limit value, Since deterioration and demulsibility deteriorate, it is not preferable respectively.

  Moreover, it is preferable that the lubricating oil composition for internal combustion engines of this invention contains an ashless friction modifier from the point which can further improve the friction characteristic. As the ashless friction modifier, any compound usually used as a friction modifier for lubricating oils can be used. For example, an alkyl group or alkenyl group having 6 to 30 carbon atoms, particularly a straight chain having 6 to 30 carbon atoms. Amine compound, fatty acid ester, fatty acid amide, fatty acid, fatty alcohol, aliphatic ether, hydrazide (eg oleyl hydrazide), semicarbazide, urea, ureido, biuret having at least one chain alkyl group or straight chain alkenyl group in the molecule And ashless friction modifiers.

  The content of the friction modifier in the lubricating oil composition for an internal combustion engine of the present invention is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and still more preferably 0.00% by mass based on the total amount of the composition. It is 3% by mass or more, preferably 3% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass or less. If the content of the friction modifier is less than the lower limit, the effect of reducing friction due to the addition tends to be insufficient, and if the content exceeds the upper limit, the effects of the wear resistance additive and the like are hindered. It tends to be easy or the solubility of the additive tends to deteriorate.

  Moreover, it is preferable that the lubricating oil composition for internal combustion engines of this invention further contains a metal type detergent from the point of detergency. It is preferable to use at least one alkaline earth metal detergent selected from alkaline earth metal sulfonates, alkaline earth metal phenates, and alkaline earth metal salicylates as the metal detergent.

  Alkaline earth metal sulfonates include alkaline earth metal salts of alkyl aromatic sulfonic acids obtained by sulfonated alkyl aromatic compounds having a molecular weight of 300 to 1,500, preferably 400 to 700, particularly magnesium salts and / or Or it is a calcium salt and a calcium salt is used preferably. Specific examples of the alkyl aromatic sulfonic acid include so-called petroleum sulfonic acid and synthetic sulfonic acid. As the petroleum sulfonic acid here, generally used are those obtained by sulfonating an alkyl aromatic compound in a lubricating oil fraction of mineral oil, or so-called mahoganic acid that is by-produced when white oil is produced. As synthetic sulfonic acids, for example, sulfonated alkylbenzenes having linear or branched alkyl groups, which are obtained as a by-product from an alkylbenzene production plant, which is a raw material for detergents, or are obtained by alkylating polyolefins to benzene. Or sulfonated alkylnaphthalene such as dinonylnaphthalene is used. The sulfonating agent for sulfonating these alkyl aromatic compounds is not particularly limited, but usually fuming sulfuric acid or anhydrous sulfuric acid is used.

  Alkaline earth metal phenates include alkylphenols, alkylphenol sulfides, alkaline earth metal salts of Mannich reactants of alkylphenols, particularly magnesium salts and / or calcium salts. For example, in the following general formulas (17) to (19): Mention may be made of the compounds represented.

In the general formulas (17) to (19), R ⁴¹ , R ⁴² , R ⁴³ , R ⁴⁴ , R ⁴⁵ and R ⁴⁶ may be the same or different and each have 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms. Wherein M ¹ , M ² and M ³ each represent an alkaline earth metal, preferably calcium and / or magnesium, and x represents 1 or 2. In the above formula, R ⁴¹ , R ⁴² , R ⁴³ , R ⁴⁴ , R ⁴⁵ and R ⁴⁶ are specifically butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, Undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group , Octacosyl group, nonacosyl group, triacontyl group and the like, which may be linear or branched. These may also be primary alkyl groups, secondary alkyl groups or tertiary alkyl groups.

  Examples of the alkaline earth metal salicylate include alkaline earth metal salts of allyl salicylic acid, particularly magnesium salts and / or calcium salts, and examples include those represented by the following general formula (20).

In the general formula (20), R ⁴⁷ represents a linear or branched alkyl group having 1 to 30, preferably 6 to 18 carbon atoms, n represents an integer of 1 to 4, preferably 1 or 2, M ⁴ represents an alkaline earth metal, preferably calcium and / or magnesium. Specific examples of R ⁴⁷ include butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl Group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group, nonacosyl group, triacontyl group, etc. It may be a branch. These may also be primary alkyl groups, secondary alkyl groups or tertiary alkyl groups.

  Further, as the alkaline earth metal sulfonate, alkaline earth metal phenate and alkaline earth metal salicylate, the above alkyl aromatic sulfonic acid, alkylphenol, alkylphenol sulfide, Mannich reaction product of alkylphenol, allylic salicylic acid, etc. are directly used as magnesium and Reacting with alkaline earth metal bases such as calcium alkaline earth metal oxides and hydroxides, or once replacing alkali metal salts such as sodium salts and potassium salts with alkaline earth metal salts Neutral (normal salt) alkaline earth metal sulfonate, neutral (normal salt) alkaline earth metal phenate and neutral (normal salt) alkaline earth metal salicylate as well as neutral alkaline earth metal sulfonate obtained by , Neutral alkaline earth metal fer Basic alkaline earth metal sulfonate, basic alkaline earth metal obtained by heating a salt and neutral alkaline earth metal salicylate and excess alkaline earth metal salt or alkaline earth metal base in the presence of water Alkaline earth metal hydroxide and carbon dioxide in the presence of phenate and basic alkaline earth metal salicylate, neutral alkaline earth metal sulfonate, neutral alkaline earth metal phenate and neutral alkaline earth metal salicylate Or overbased (superbasic) alkaline earth metal sulfonates, overbased (superbasic) alkaline earth metal phenates and overbased (superbasic) alkaline earths obtained by reacting with boric acid Metal salicylates are also included.

  In the present invention, the above-mentioned neutral alkaline earth metal salts, basic alkaline earth metal salts, overbased (superbasic) alkaline earth metal salts, and mixtures thereof can be used. Among these, from the viewpoint of maintaining cleanliness over a long period of time, it is preferable to use a combination of overbased calcium sulfonate and overbased calcium phenate, or overbased calcium salicylate. It is particularly preferred to use calcium salicylate. Metal-based detergents are usually commercially available in a state diluted with a light lubricating base oil or the like, and are available, but generally the metal content is 1.0 to 20% by mass, preferably Is preferably 2.0 to 16% by mass. Although the total base number of the alkaline earth metal detergent used in the present invention is arbitrary, it is usually desirable to use a total base number of 500 mgKOH / g or less, preferably 150 to 450 mgKOH / g. The total base number referred to here is JISK2501 (1992) "Petroleum products and lubricants-Neutralization number test method". It means the total base number by the perchloric acid method measured according to the above.

  The content of the metallic detergent in the lubricating oil composition for an internal combustion engine of the present invention is arbitrary, but is 0.1 to 10% by mass, preferably 0.5 to 8% by mass, more preferably based on the total amount of the composition. It is desirable to contain 1-5 mass%. When this content exceeds 10 mass%, since the effect only corresponding to the content is not acquired, it is unpreferable.

  Moreover, it is preferable that the lubricating oil composition for internal combustion engines of this invention contains a viscosity index improver from the point which can further improve a viscosity-temperature characteristic. Such viscosity index improvers include non-dispersed or dispersed polymethacrylates, dispersed ethylene-α-olefin copolymers or hydrides thereof, polyisobutylene or hydrides thereof, styrene-diene hydrogenated copolymers, styrene. -Maleic anhydride ester copolymers and polyalkylstyrenes are mentioned, among which the weight average molecular weight is 10,000 to 1,000,000, preferably 100,000 to 900,000, more preferably 150,000 to 500. , 000, more preferably 180,000 to 400,000 non-dispersed viscosity index improvers and / or dispersed viscosity index improvers are preferably used.

  Specifically, as the non-dispersion type viscosity index improver, a monomer selected from compounds represented by the following general formulas (21), (22) and (23) (hereinafter referred to as “monomer (M-1)”) And a copolymer of two or more monomers (M-1) or a hydride thereof. On the other hand, as the dispersion type viscosity index improver, specifically, a monomer selected from the compounds represented by the general formulas (24) and (25) (hereinafter referred to as “monomer (M-2)”). One of the monomers (M-1) selected from the compounds represented by the general formulas (21) to (23) or those obtained by introducing an oxygen-containing group into two or more types of copolymers or hydrides thereof Examples thereof include copolymers of two or more types and one or more types of monomers (M-2) selected from the compounds represented by the general formulas (24) and (25), or hydrides thereof. .

In the general formula ^{(21), R 48} represents a hydrogen atom or a methyl ^{group, R 49} represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. Specific examples of the alkyl group having 1 to 18 carbon atoms represented by R ⁴⁹ include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group. Examples thereof include a group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, and an octadecyl group (these alkyl groups may be linear or branched).

In the general formula (22), R ⁵⁰ represents a hydrogen atom or a methyl group, and R ⁵¹ represents a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms. Specific examples of the hydrocarbon group having 1 to 12 carbon atoms represented by R ⁵¹ include methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, Alkyl groups such as decyl group, undecyl group, dodecyl group (these alkyl groups may be linear or branched); C5-C7 cycloalkyl groups such as cyclopentyl group, cyclohexyl group, cycloheptyl group; methyl Cyclopentyl group, dimethylcyclopentyl group, methylethylcyclopentyl group, diethylcyclopentyl group, methylcyclohexyl group, dimethylcyclohexyl group, methylethylcyclohexyl group, diethylcyclohexyl group, methylcycloheptyl group, dimethylcycloheptyl group, methylethylcycloheptyl group, diethyl Cycloheptyl group, etc. An alkylcycloalkyl group having 6 to 11 carbon atoms (the substitution position of these alkyl groups with the cycloalkyl group is arbitrary);
Alkenyl groups such as butenyl group, pentenyl group, hexenyl group, heptenyl group, octenyl group, nonenyl group, decenyl group, undecenyl group, dodecenyl group, etc. (These alkenyl groups may be linear or branched, and position of double bond Is also optional);
Aryl group such as phenyl group, naphthyl group: alkylaryl group having 7 to 12 carbon atoms such as tolyl group, xylyl group, ethylphenyl group, propylphenyl group, butylphenyl group, pentylphenyl group, hexylphenyl group (these alkyl groups) May be linear or branched, and the position of substitution on the aryl group is also arbitrary); carbon number of benzyl, phenylethyl, phenylpropyl, phenylbutyl, phenylpentyl, phenylhexyl, etc. 7-12 arylalkyl groups (these alkyl groups may be linear or branched); and the like.

In the general formula (23), X ¹ and X ² are each independently a hydrogen atom, an alkoxy group having 1 to 18 carbon atoms (—OR ⁵² : R ⁵² is an alkyl group having 1 to 18 carbon atoms) or a carbon number. 1-18 monoalkylamino group ^{(-NHR 53: R} 53 is an alkyl group having 1 to 18 carbon atoms).

In the general formula (23), R ⁵⁴ represents a hydrogen atom or a methyl group, R ⁵⁵ represents an alkylene group having 1 to 18 carbon atoms, Y ¹ represents ¹ to 2 nitrogen atoms, and 0 to 2 oxygen atoms. 1 represents an amine residue or heterocyclic residue, and m is 0 or 1. Specific examples of the alkylene group represented by R ⁵⁵ having 1 to 18 carbon atoms include ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, Examples include an undecylene group, a dodecylene group, a tridecylene group, a tetradecylene group, a pentadecylene group, a hexadecylene group, a heptadecylene group, and an octadecylene group (these alkylene groups may be linear or branched). Specific examples of the group represented by Y ¹ include dimethylamino group, diethylamino group, dipropylamino group, dibutylamino group, anilino group, toluidino group, xylidino group, acetylamino group, benzoylamino group, Examples thereof include a morpholino group, a pyrrolyl group, a pyrrolino group, a pyridyl group, a methylpyridyl group, a pyrrolidinyl group, a piperidinyl group, a quinonyl group, a pyrrolidonyl group, a pyrrolidono group, an imidazolino group, and a pyrazino group.

In the above general formula (25), R ⁵⁶ represents a hydrogen atom or a methyl group, and Y ² represents an amine residue or a heterocyclic residue containing 1 to 2 nitrogen atoms and 0 to 2 oxygen atoms. Specific examples of the group represented by Y ² include a dimethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, an anilino group, a toluidino group, a xylidino group, an acetylamino group, a benzoylamino group, and a morpholino group. Pyrrolyl group, pyrrolino group, pyridyl group, methylpyridyl group, pyrrolidinyl group, piperidinyl group, quinonyl group, pyrrolidonyl group, pyrrolidono group, imidazolino group, pyrazino group and the like.

  Preferable examples of the monomer (M-1) are specifically alkyl acrylates having 1 to 18 carbon atoms, alkyl methacrylates having 1 to 18 carbon atoms, olefins having 2 to 20 carbon atoms, styrene, methylstyrene, and anhydrous maleic acid. Examples thereof include acid esters, maleic anhydride amides and mixtures thereof.

  Preferable examples of the monomer (M-2) are specifically dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-methyl-5-vinylpyridine, morpholinomethyl methacrylate, morpholinoethyl. Examples thereof include methacrylate, N-vinyl pyrrolidone and a mixture thereof.

  Copolymerization of a copolymer of one or more monomers selected from the (M-1) compound and one or more monomers selected from the (M-2) compound. The molar ratio is generally about monomer (M-1): monomer (M-2) = 80: 20 to 95: 5. The production method is arbitrary, but usually a copolymer is easily obtained by radical solution polymerization of monomer (M-1) and monomer (M-2) in the presence of a polymerization initiator such as benzoyl peroxide. It is done.

  Among the above-described viscosity index improvers, polymethacrylate viscosity index improvers are preferable because they are superior in low-temperature fluidity.

  The blending amount of the viscosity index improver in the lubricating oil composition for internal combustion engines of the present invention is preferably 0.1 to 15% by mass, more preferably 0.5 to 5% by mass, based on the total amount of the composition. When the content of the viscosity index improver is less than 0.1% by mass, the effect of improving the viscosity-temperature characteristics due to the addition tends to be insufficient, and when it exceeds 15% by mass, the initial extreme pressure property is reduced. It tends to be difficult to maintain for a long time.

  In the lubricating oil composition for an internal combustion engine of the present invention, for the purpose of further improving its performance, in addition to the above additives, a corrosion inhibitor, a rust inhibitor, a demulsifier, and a metal deactivation are added as necessary. You may mix | blend various additives, such as an agent, a pour point depressant, a rubber swelling agent, an antifoamer, and a coloring agent, individually or in combination.

  Examples of the corrosion inhibitor include benzotriazole, tolyltriazole, thiadiazole, and imidazole compounds.

  Examples of the rust inhibitor include petroleum sulfonate, alkylbenzene sulfonate, dinonylnaphthalene sulfonate, alkenyl succinic acid ester, and polyhydric alcohol ester.

  Examples of the demulsifier include polyalkylene glycol nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and polyoxyethylene alkyl naphthyl ether.

  Examples of metal deactivators include imidazoline, pyrimidine derivatives, alkylthiadiazoles, mercaptobenzothiazoles, benzotriazoles or derivatives thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bis. Examples include dialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, and β- (o-carboxybenzylthio) propiononitrile.

  As the pour point depressant, a known pour point depressant can be arbitrarily selected according to the properties of the lubricating base oil, but the weight average molecular weight is more than 50,000 and not more than 150,000, preferably 80 1 to 120,000 polymethacrylates are preferred.

  As the antifoaming agent, any compound usually used as an antifoaming agent for lubricating oil can be used, and examples thereof include silicones such as dimethyl silicone and fluorosilicone. One or two or more compounds arbitrarily selected from these can be blended in any amount.

  As the colorant, any compound that is usually used can be used, and any amount can be blended. Usually, the blending amount is 0.001 to 1.0% by mass based on the total amount of the composition. is there.

  When these additives are contained in the lubricating oil composition of the present invention, the content is based on the total amount of the composition, 0.005 to 5% by mass for the corrosion inhibitor, the rust inhibitor, and the demulsifier, respectively, and the metal inertness. 0.005 to 1% by mass for the agent, 0.05 to 1% by mass for the pour point depressant, 0.0005 to 1% by mass for the antifoaming agent, and 0.001 to 1.0% by mass for the colorant. Usually selected by range.

  The lubricating oil composition for an internal combustion engine of the present invention can contain an additive containing sulfur as a constituent element as described above, but the total sulfur content of the lubricating oil composition (sulfur resulting from the lubricating base oil and additives) The total amount of min) is preferably 0.05 to 0.3% by mass from the viewpoint of suppressing the solubility of the additive and the consumption of the base number due to the generation of sulfur oxides under high-temperature oxidation conditions. More preferably, it is 0.08-0.25 mass%, More preferably, it is 0.1-0.2 mass%, Most preferably, it is 0.12-0.18 mass%.

Further, the kinematic viscosity at 100 ° C. of the lubricating oil composition for an internal combustion engine of the present invention is usually 4 to 24 mm ² / s, but the oil film thickness that suppresses seizure and wear is maintained, and stirring resistance From the point which suppresses the increase in this, Preferably it is 5-18 mm < ² > / s, More preferably, it is 6-15 mm < ² > / s, More preferably, it is 7-12 mm < ² > / s.

  The lubricating oil composition for an internal combustion engine of the present invention having the above-described configuration is excellent in thermal / oxidation stability or further in viscosity-temperature characteristics, friction characteristics and volatilization prevention, and is used for two-wheeled vehicles, four-wheeled vehicles, power generation, When used as a lubricating oil for an internal combustion engine such as a marine gasoline engine, a diesel engine, an oxygen-containing compound-containing engine, a gas engine, etc., long drain and energy saving can be sufficiently realized.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

[Manufacture of lubricating base oil]
(Base oil 1)
The fraction separated by vacuum distillation in the step of refining the solvent refined base oil was subjected to hydrogenation after solvent extraction with furfural and then dewaxed with a methyl ethyl ketone-toluene mixed solvent. A wax obtained by further deoiling the slack wax removed during the solvent dewaxing (hereinafter referred to as “WAX1”) was used as a raw material for the lubricating base oil. Table 1 shows the properties of WAX1.

Next, hydrocracking of WAX1 was performed under the conditions of a hydrogen partial pressure of 5 MPa, an average reaction temperature of 350 ° C., and LHSV1hr ⁻¹ in the presence of a hydrocracking catalyst. As the hydrocracking catalyst, a catalyst in which 3% by mass of nickel and 15% by mass of molybdenum were supported on an amorphous silica / alumina carrier (silica: alumina = 20: 80 (mass ratio)) was used in a sulfurized state.

  Next, the cracked product obtained by the above hydrocracking was distilled under reduced pressure to obtain a 26% by volume lubricating oil fraction with respect to the raw material oil. For this lubricating oil fraction, solvent dewaxing was carried out using a methyl ethyl ketone-toluene mixed solvent under the conditions of a solvent / oil ratio of 4 times and a filtration temperature of -25 ° C. to obtain a target lubricating base oil (hereinafter referred to as “base oil 1”). "). Various properties and performance evaluation test results of the base oil 1 are shown in Table 2.

[Examples 1 and 2 and Comparative Examples 1 to 7]
In Examples 1 and 2, lubricating oil compositions having the compositions shown in Table 3 were prepared using the base oil 1 and the following base oils and additives. Moreover, in Comparative Examples 1-4, the lubricating oil composition which has a composition shown in Table 4 using the base oil and additive shown below was prepared. Moreover, in Comparative Examples 5-7, the lubricating oil composition which has a composition shown in Table 5 using the base oil 1 and the additive shown below was prepared. The sulfur content, phosphorus content, kinematic viscosity at 100 ° C., base number, and acid value of the obtained lubricating oil composition are shown in Tables 3-5.
(Base oil)
Base oil 2: Paraffinic hydrocracked base oil (saturated component: 94.8% by mass, ratio of cyclic saturated component in saturated component: 46.8% by mass, sulfur component: less than 0.001% by mass, at 100 ° C. (Kinematic viscosity: 4.1 mm ² / s, viscosity index: 121, refractive index at ₂₀ ° C .: 1.4640, n ₂₀ −0.002 × kv100: 1.456)
Base oil 3: Refined paraffinic base oil (saturated content: 77% by mass, sulfur content: 0.12% by mass, kinematic viscosity at 100 ° C .: 4.0 mm ² / s, viscosity index: 102)
(Ashless antioxidant that does not contain sulfur as a constituent element)
A1: Alkyldiphenylamine A2: Octyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (ashless antioxidant containing sulfur as a constituent element and organic molybdenum compound)
B1: Ashless dithiocarbamate (sulfur content: 29.4% by mass)
B2: Ditridecylamine complex of molybdenum (molybdenum content: 10.0% by mass)
(Antiwear agent)
C1: zinc dialkyldithiophosphate (phosphorus content: 7.4% by mass, alkyl group: primary octyl group)
C2: zinc dialkyldithiophosphate (phosphorus content: 7.2 mass%, alkyl group: secondary butyl group or secondary hexyl group mixture)
(Ashless dispersant)
D1: Polybutenyl succinimide (bis type, weight average molecular weight: 8,500, nitrogen content: 0.65 mass%)
(Ashless friction modifier)
E1: Glycerin fatty acid ester (trade name: MO50, manufactured by Kao Corporation)
(Other additives)
F1: A package containing a metallic detergent, a viscosity index improver, a pour point depressant and an antifoaming agent.

[Heat and oxidation stability evaluation test]
Regarding the lubricating oil compositions of Examples 1 and 2 and Comparative Examples 1 to 7, JIS K 2514 4. The thermal / oxidation stability test (test temperature: 165.5 ° C.) was performed in accordance with the method (ISOT) in the item, and the base number retention rate after 24 hours and 72 hours was obtained. The obtained results are shown in Tables 3-5.

[Friction characteristic evaluation test: SRV (micro reciprocating friction) test]
About the lubricating oil composition of Examples 1, 2 and Comparative Examples 1-7, the SRV test was implemented as follows and the friction characteristic was evaluated. First, test pieces (steel balls (diameter 18 mm) / disk, SUJ-2) for SRV testing machine manufactured by Optimol were prepared, and the surface roughness was finished to Ra 0.2 μm or less. The test piece is mounted on an SRV testing machine manufactured by Optimol Co., Ltd., and the shell lubricating oil composition is dropped on the sliding surface of the test piece, and the test is performed under the conditions of a temperature of 80 ° C., a load of 30 N, an amplitude of 3 mm, and a frequency of 50 Hz. The average coefficient of friction from the time when 15 minutes passed until the time when 30 minutes passed after the start of the test was measured. The obtained results are shown in Tables 3-5.

  In addition, the SRV test similar to the above using the lubricating oil compositions of Examples 1 and 2 and Comparative Examples 1 to 4 after 24 hours in the thermal and oxidation stability evaluation test (hereinafter referred to as “used oil”). Carried out. The obtained results are shown in Tables 3-5.

  As shown in Table 3, the lubricating oil compositions for internal combustion engines of Examples 1 and 2 had a small base number decrease rate after 24 hours in the oxidation stability test, and the remaining base number was sufficient even after 72 hours. From this, it can be seen that the oxidation stability is excellent. Moreover, the lubricating oil compositions for internal combustion engines of Examples 1 and 2 have a low initial friction coefficient, and the friction coefficient is less than 0.1 even after 24 hours in the oxidation stability test. It turns out that it is excellent in maintainability.

  On the other hand, the lubricating oil compositions for internal combustion engines of Comparative Examples 1 to 7 have a low base friction because the base number retention rate is inferior and the coefficient of friction exceeds 0.1 for 24 hours after the oxidation stability test. It turns out that it is inferior to maintainability.

  Furthermore, from the comparison between Example 1 and Comparative Examples 5 and 7 and the comparison between Comparative Example 1 and Comparative Examples 3 and 4, the lubricating oil composition for an internal combustion engine of Example 1 is composed of components (A) and (B). It can be seen that the effect of improving the base number retention rate, oxidation stability, and low friction retention by the addition of is remarkable.

Claims (2)

A lubricating base oil containing 90% by mass or more of a saturated component and having a cyclic saturated component in the saturated component of 10 to 40% by mass;
An ashless antioxidant that does not contain sulfur as a constituent element;
A lubricating oil composition for internal combustion engines, comprising an ashless antioxidant containing sulfur as a constituent element and at least one selected from organic molybdenum compounds. A lubricating base oil that satisfies the condition represented by the following formula (1):
An ashless antioxidant that does not contain sulfur as a constituent element;
A lubricating oil composition for internal combustion engines, comprising an ashless antioxidant containing sulfur as a constituent element and at least one selected from organic molybdenum compounds.
1.440 ≦ n ₂₀ −0.002 × kv100 ≦ 1.453 (1)
_{Wherein, n 20} is the refractive index at 20 ° C. of the lubricating base oil, kv100 represents the kinematic viscosity at 100 ° C. of the lubricating base oil ^(mm 2 / s). ]