JP5379345B2 - Lubricating oil composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a lubricating oil composition that satisfies both heat/oxidation stability and sludge control at high levels and in good balance and realizes sufficient elongation of service life when used as a lubricating oil for a steam turbine, gas turbine, rotary gas compressor, hydraulic equipment, etc. <P>SOLUTION: The lubricating oil composition comprises a lubricant base oil having %C<SB>A</SB>of &le;2, %C<SB>P</SB>/%C<SB>N</SB>of &ge;6 and an iodine value of &le;2.5 and an ashless antioxidant containing no sulfur as a constituent element. The content of the ashless antioxidant is 0.3-5 mass% based on the total of the composition. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a lubricating oil composition.

  Lubricating oils used in steam turbines, gas turbines, rotary gas compressors, hydraulic equipment, etc. are used at high temperatures and are circulated so that they can withstand long-term use. is important. In particular, the above facilities or equipment tend to dislike precipitation of insoluble matter (sludge) generated in the lubricating oil. For example, if the deposited sludge component adheres to the bearing of the rotating body, it causes heat generation, and in the worst case, the bearing is damaged. Moreover, when sludge is deposited, it may cause operational problems such as clogging of a filter provided in the circulation line. Furthermore, when sludge accumulates on the control valve and the control system malfunctions, the apparatus must be stopped. Therefore, in addition to thermal and oxidation stability, the lubricating oil used in such fields is required to have a characteristic that sludge does not easily precipitate (hereinafter referred to as “sludge suppression”).

Therefore, in conventional lubricating oils, a highly refined mineral oil or a synthetic hydrocarbon oil represented by a hydrogenated product of poly-α-olefins is used as a base oil, and an antioxidant is blended. Improvement of heat / oxidation stability and sludge suppression is achieved (see, for example, Patent Document 1 below).
Japanese Patent Laid-Open No. 7-252489

  By the way, in recent power generation facilities, a combined cycle power generation that combines a gas turbine using a high-temperature combustion gas as a working medium or a combination of a gas turbine and a steam turbine for the purpose of increasing the power generation efficiency and effectively utilizing energy. A lot of facilities are in operation. The combustion gas temperature of gas turbines used in business power generation facilities in the 1980s was about 1,100 ° C. However, in recent years, with the improvement in heat resistance of the constituent materials of gas turbines, the temperature has increased to about 1,500 ° C. Higher temperatures are being promoted. In addition, the rotary gas compressor inherently has a mechanism in which the lubricating oil and the high-temperature compressed gas come into contact with each other. However, in recent years, the heat load on the lubricating oil has been greatly increased as the compressor becomes more compact. It is increasing.

  As described above, the use conditions of the lubricating oil in the above facilities or equipment are becoming increasingly severe, and it has become difficult to achieve sufficient thermal / oxidative stability and sludge suppression with the conventional lubricating oil. .

  Increasing the amount of antioxidant can be considered as a method to improve the thermal / oxidative stability of the lubricating oil, but in this case, sludge formation of the antioxidant itself becomes a problem, so thermal / oxidative stability and sludge suppression are considered. It cannot be a fundamental solution for balancing sex. In particular, when a synthetic hydrocarbon oil such as a hydrogenated product of poly-α-olefins is used as a base oil, the base oil is inherently difficult to dissolve an additive or its oxidative degradation product. Increasing the inhibitor is undesirable.

  The present invention has been made in view of such a situation, and heat / oxidation stability and sludge suppression are balanced at a high level in a balanced manner, such as a steam turbine, a gas turbine, a rotary gas compressor, An object of the present invention is to provide a lubricating oil composition capable of realizing a sufficiently long life when used as a lubricating oil for hydraulic equipment.

In order to solve the above-mentioned problems, the present invention is designed to remove a lubricating oil fraction obtained by atmospheric distillation and / or vacuum distillation of a crude oil, solvent extraction, solvent extraction, hydrocracking, solvent dewaxing, catalytic desorption. Select from paraffinic mineral oil, normal paraffinic base oil and isoparaffinic base oil refined by combining one or more of wax, hydrorefining, sulfuric acid washing or clay treatment alone or in combination At least one lubricating base oil, wherein% C _A is 2 or less,% C _N is 8 or more,% C _P /% C _N is 9.75 or more and 35 or less, and iodine value is 2.5 or less. A certain lubricating oil base oil and an ashless antioxidant that does not contain sulfur as a constituent element, and the content of the ashless antioxidant is 0.3 to 5 mass based on the total amount of the composition % der is, as ashless antioxidant include phenyl -α- naphthylamine And the ratio of the alkylated diphenylamine compound in the total of the phenyl-α-naphthylamine compound and the alkylated diphenylamine compound is 0.1 to 0.9 by mass ratio. providing a lubricating oil composition characterized in that there.

Since the lubricating base oil contained in the lubricating oil composition of the present invention has% C _A ,% C _P /% C _N , and iodine value satisfying the above-mentioned conditions, it itself has thermal and oxidative stability. Excellent in properties. Furthermore, the lubricating base oil is capable of expressing its functions at a higher level while stably dissolving and retaining the additive when an additive such as an ashless antioxidant is blended. is there. And, by adding the ashless antioxidant that does not contain sulfur as a constituent element to the lubricating base oil having such excellent characteristics so that its content satisfies the above conditions, thermal and oxidation stability And sludge suppression can be balanced at a high level in a well-balanced manner. Therefore, according to the lubricating oil composition of the present invention, it is possible to achieve a sufficiently long life when used as a lubricating oil for steam turbines, gas turbines, rotary gas compressors, hydraulic equipment, and the like.

  The lubricating oil composition of the present invention preferably further contains an alkyl group-substituted aromatic hydrocarbon compound. Thereby, thermal / oxidation stability and sludge suppression can be achieved at a higher level.

  The alkyl group-substituted aromatic hydrocarbon compound is at least one selected from alkylbenzene, alkylnaphthalene, alkylbiphenyl, and alkyldiphenylalkane, and has one or two alkyl groups having 8 to 30 carbon atoms. Compounds are preferred.

The lubricating oil composition of the present invention contains both a phenyl-α-naphthylamine compound and an alkylated diphenylamine compound as an ashless antioxidant, and is a total of the phenyl-α-naphthylamine compound and the alkylated diphenylamine compound. ratio of alkylated diphenylamine compound occupied in the amount, by mass ratio, Ru der 0.1-0.9. By using a phenyl-α-naphthylamine compound and an alkylated diphenylamine compound as ashless antioxidants in such a manner that the content ratios of the two satisfy the above conditions, the heat / antioxidant property and sludge inhibiting property are further improved. It becomes possible to achieve both.

  According to the present invention, heat / oxidation stability and sludge suppression are balanced at a high level in a balanced manner, and when used as lubricating oil for steam turbines, gas turbines, rotary gas compressors, hydraulic equipment, etc. Provided is a lubricating oil composition capable of realizing a sufficiently long life.

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

In the present invention,% C _A of 2 or _less,% C P _/% C _N is 6 or more, the lubricating base oil having an iodine value of 2.5 or less (hereinafter, simply referred to as "lubricating base oil according to the present invention" .) Is used.

% C _A of the lubricating base oil according to the present invention is 2 or less as described above, preferably 1.5 or less, more 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 be lowered. 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.

The ratio of the lubricating base% in oil _{C P} and% _{C N} of the present invention _{(% C P /% C N} ) is at street 6 or above, and more preferably 7 or more. When% C _P /% _CN is less than the above lower limit, viscosity-temperature characteristics, thermal / oxidative stability and friction characteristics are reduced, and further, when an additive is blended in a lubricating base oil The effectiveness of the agent is reduced. _{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.

Further, the% C _p of the lubricating base oil according to the present invention is preferably 80 or more, more preferably 82 to 99, still more preferably 85 to 95, and particularly preferably 87 to 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 preferably 19 or less, more preferably 5 to 15, more preferably 7 to 13, particularly preferably 8 to 12. If the% C _N value 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.

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.

  In addition, the iodine value of the lubricating base oil according to the present invention is 2.5 or less as described above, preferably 1.5 or less, more preferably 1 or less, still more preferably 0.8 or less, Although it may be less than 0.01, it is preferably 0.01 or more, more preferably 0.1 or more, and still more preferably 0.5 or more, from the viewpoint of small effects that are commensurate with it and economy. is there. By setting the iodine value of the lubricating base oil to 2.5 or less, the thermal and oxidation stability can be dramatically improved. The “iodine value” in the present invention means an iodine value measured by an indicator titration method of JIS K 0070 “acid value, saponification value, iodine value, hydroxyl value, and unsaponification value of a chemical product”. .

The lubricating base oil according to the present invention is not particularly limited as long as% C _A ,% C _P /% C _N , and iodine value satisfy the above conditions. 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 % C _A ,% C among paraffinic mineral oils, normal paraffinic base oils, isoparaffinic base oils, etc., which are refined by combining one or more kinds of purification treatments such as washing and clay treatment alone or in combination of two or more. Examples include _P /% C _N and iodine value satisfying the above conditions. 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 (such as slack wax) obtained by the lubricant dewaxing process and / or synthetic wax (Fischer-Tropsch wax, GTL wax, etc.) obtained by the gas-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 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 not more than mass%, more preferably not more than 50 mass%, still more preferably not more than 25 mass%, particularly preferably not more than 10 mass%, and preferably not less than 0.5 mass%. More preferably, it is 1% by 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. The slack waxes A and B may be subjected to a desulfurization treatment depending on the type and characteristics of the hydrocracking / isomerization catalyst, and the sulfur content in that case is preferably 0.01. It is at most mass%, more preferably at most 0.001 mass%.

In the above-described manufacturing method A, by using the slack wax A as a raw _{material,% C A,% C P} /% C N and the iodine value obtained suitably such lubricating base oil in each of the above conditions are satisfied the present invention be able to. 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. The sulfur content of the synthetic wax is preferably 0.01% by mass or less, more preferably 0.001% by mass or less, and further 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.

  The raw material oil for producing the lubricating base oil according to the present invention is a raw material oil containing slack wax and / or synthetic wax, and the oil content is preferably 60% by mass or less, more preferably 50% by mass. % Or less, more preferably 25% by mass or less.

  Further, the content of the saturated component in the lubricating base oil according to the present invention is preferably 90% by mass or more, more preferably 93% by mass or more, and still more preferably 95% by mass or more, based on the total amount of the lubricating base oil. In addition, the ratio of the cyclic saturated component in the saturated component is preferably 40% by mass or less, more preferably 0.1 to 40% by mass, still more preferably 2 to 30% by mass, and still more preferably 5 to 5% by mass. It is 25 mass%, Most preferably, it is 10-21 mass%. By satisfying the above conditions for the content of the saturated component and the ratio of the cyclic saturated component in the saturated component, the viscosity-temperature characteristics and thermal / oxidative stability can be achieved at a higher level, and the lubrication When an additive is blended in the oil base oil, the function of the additive can be expressed at a higher level while the additive is sufficiently stably dissolved and held in the lubricant base oil. Furthermore, it is possible to improve the friction characteristics of the lubricating base oil itself, and as a result, it is possible to achieve an improvement in friction reduction effect and an improvement in energy saving.

  In addition, when content of a saturated part is less than 90 mass%, it exists in the tendency for a viscosity-temperature characteristic, thermal / oxidation stability, and a friction characteristic to become inadequate. Moreover, when the ratio of the cyclic | annular saturated part to a saturated part exceeds 40 mass%, when an additive is mix | blended with lubricating base oil, it exists in the tendency for the effectiveness of the said additive to fall. Furthermore, when the ratio of the cyclic saturated component to the saturated component is less than 0.1% by mass, when the additive is blended with the lubricating base oil, the solubility of the additive is reduced and the lubricating base oil The effective amount of the additive dissolved and retained tends to decrease, and the function of the additive cannot be effectively obtained. 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.

  In the lubricating base oil according to the present invention, the ratio of the cyclic saturated component in the saturated component is 40% by mass or less is equivalent to the non-cyclic saturated component in the saturated component being 60% by mass or more. . 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 5-96 mass%, More preferably, it is 60-95 mass%, More preferably, it is 70-92 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. The proportion of linear paraffin in the lubricating base oil is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.2% by mass or less, based on the total amount of the lubricating oil base oil. It is. When the ratio of the straight-chain paraffin satisfies the above conditions, a lubricating base oil having more excellent low-temperature viscosity characteristics can be obtained.

  Further, in the lubricating base oil according to the present invention, the content of the saturated component of one ring and the saturated component of two or more rings in the saturated component is not particularly limited, but the ratio of the saturated component of two or more rings in the saturated component is It is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 3% by mass or more, particularly preferably 5% by mass or more, and 40% by mass. The content is preferably 20% by mass or less, more preferably 15% by mass or less, and particularly preferably 11% by mass or less. Further, the percentage of saturated one ring in the saturated portion may be 0% by mass, preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 3% by mass or more, particularly preferably 4%. Further, it is preferably 40% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, and particularly preferably 11% by mass or less.

Moreover, in the lubricating base oil according to the present invention, the ratio (M _A / M _B ) of the mass (M _A ) of the monocyclic saturated component contained in the cyclic saturated component and the mass (M _B ) of the saturated component of two or more rings. ) Is preferably 20 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1 or less. _Although it may be a 0 M A / _{M B,} preferably 0.1 or more, more preferably 0.3 or more, more preferably 0.5 or more. By the above condition is satisfied M A _/ M _B, the viscosity - a temperature characteristic and heat and oxidation stability can be further compatible at a high level.

Moreover, in the lubricating base oil according to the present invention, the ratio (M _A / M _c ) between the mass of the monocyclic saturated component (M _A ) and the mass of the bicyclic saturated component (M _c ) contained in the cyclic saturated component is , Preferably 3 or less, more preferably 1.5 or less, still more preferably 1.3 or less, particularly preferably 1.2 or less. _Although it may be a the _M A / M _c 0, preferably 0.1 or more, more preferably 0.3 or more, more preferably 0.5 or more. By satisfying the above conditions for M _A / M _c , the viscosity-temperature characteristics and the heat / oxidation stability can be achieved at a higher level.

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

  Further, the ratios of the cyclic saturated component, the single ring saturated component, the two or more saturated components and the non-cyclic saturated component in the saturated component as used in the present invention are naphthenic components measured in accordance with ASTM D 2786-91, respectively. (Measuring target: 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.

Also, the aromatic content in the lubricating base oil according to the present _{invention,% C A,% C P} /% C N, and although the iodine value is not particularly limited as long as the above conditions are satisfied, lubricating base oils the total amount Is preferably 7% by mass or less, more preferably 5% by mass or less, further preferably 4% by mass or less, particularly preferably 3% by mass or less, and preferably 0.1% by mass or more, more preferably Is 0.5% by mass or more, more preferably 1% by mass or more, and particularly preferably 1.5% by mass or more. 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, the aromatic component as used in the field of this invention 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.

  The viscosity index of the lubricating base oil according to the present invention is preferably 110 or more. When the viscosity index is less than the lower limit, viscosity-temperature characteristics, thermal / oxidation stability, and further volatilization prevention properties tend to decrease. The preferred range of the viscosity index of the lubricating base oil according to the present invention depends on the viscosity grade of the lubricating base oil, and will be described in detail later.

Other properties of the lubricating base oil according to the present _{invention,% C A,% C P} /% C N, and although the iodine value is not particularly limited as long as each of the above conditions are satisfied, the lubricating oil according to the present invention The base oil preferably has various properties shown below.

  The sulfur content in the lubricating base oil according to the present invention depends on the sulfur content of 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.

In addition, the kinematic viscosity of the lubricating base oil according to the present invention is not particularly limited as long as the% C _A ,% C _P /% C _N , and iodine value satisfy the above-mentioned conditions, but the kinematic viscosity at 100 ° C. is , 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 above lubricating base oils (I) and (IV) are compared with conventional lubricating base oils with the same viscosity grade by satisfying the above conditions for% C _A ,% C _P /% C _N and iodine value, respectively. In particular, the low-temperature viscosity characteristics are excellent, and the viscosity resistance and stirring resistance can be remarkably reduced. 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 oils (II) and (V) described above are conventional lubricating base oils having the same viscosity grade because% C _A ,% C _P /% C _N , and iodine value satisfy the above-mentioned conditions. In particular, it is excellent in low-temperature viscosity characteristics, volatilization prevention properties 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.

In addition, the lubricating base oils (III) and (VI) described above are conventional lubricating base oils having the same viscosity grade because% C _A ,% C _P /% C _N , and iodine value satisfy the above conditions, respectively. Compared with, it is excellent in low temperature viscosity characteristics, 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, but the viscosity index is 110 or more in any of the lubricating base oils (I) to (VI). be able to. The viscosity index of the lubricating oils (I) and (IV) is preferably 110 to 135, more preferably 115 to 130, and still more preferably 120 to 130. 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 1.461, more preferably 1.442 to 1.460, and still more preferably 1.445 to 1.459. The refractive index of the lubricating base oils (II) and (V) at 20 ° C. is preferably 1.450 to 1.465, more preferably 1.452 to 1.463, and still more preferably 1.453 to 1.462. The refractive index of the lubricating base oils (III) and (VI) at 20 ° C. is preferably 1.455 to 1.469, more preferably 1.456 to 1.468, and still more preferably 1.457 to 1.467. 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 (1) It is preferable that ρ ₁₅ ≦ ρ.
ρ = 0.0025 × kv100 + 0.820 (1)
[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 0.825 g / cm ³ or less, more preferably 0.820 g / cm ³ or less. 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 (2). It is preferable that ≧ A.
A = 4.1 × kv100 + 97 (2)
[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.

In addition, according to the lubricating base oil of the present invention, excellent thermal / oxidative stability can be achieved by satisfying the above conditions for% C _A ,% C _P /% C _N , and iodine value, respectively. However, it is preferable to show the RBOT life shown below according to the kinematic viscosity. For example, the RBOT life of the lubricating base oils (I) and (IV) is preferably 300 min or more, more preferably 320 min or more, and further preferably 330 min or more. The RBOT life of the lubricating base oils (II) and (V) is preferably 350 min or more, more preferably 370 min or more, and further preferably 380 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 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 may be one or more of other base oils. You may use together. 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

  The lubricating oil composition of the present invention contains (A) an ashless antioxidant that does not contain sulfur as a constituent element. 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. In addition, a phenol compound having a molecular weight of 240 or more is preferable because the decomposition temperature is high and the effect is exhibited even under higher temperature conditions.

  Moreover, as an amine type ashless antioxidant which does not contain sulfur as a structural element, an amine type antioxidant and a phenol type antioxidant are preferable, and an amine type antioxidant is more preferable.

  Examples of amine-based antioxidants include phenyl-α-naphthylamine compounds, alkylated diphenylamine compounds, benzylamine compounds, and polyamine compounds. Of these, phenyl-α-naphthylamine compounds and alkyldiphenylamine compounds are preferred.

  As the phenyl-α-naphthylamine compound, phenyl-α-naphthylamine represented by the following general formula (2) is preferably used.

［式（２）中、Ｒ^１は水素原子又は炭素数１〜１６の直鎖状若しくは分枝状のアルキル基を示す。］

[In formula (2), R ¹ represents a hydrogen atom or a linear or branched alkyl group having 1 to 16 carbon atoms. ]

When R ¹ in the general formula (2) is an alkyl group, the alkyl group is linear or branched having 1 to 16 carbon atoms as described above. Specific examples of such an alkyl group include, for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, A tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, and the like (these alkyl groups may be linear or branched). When the number of carbon atoms in R ¹ exceeds 16, the proportion of functional groups in the molecule is reduced, which may adversely affect the antioxidant performance.

When R ¹ in the general formula (2) is an alkyl group, from the viewpoint of excellent solubility, R ¹ is preferably a branched alkyl group having 8 to 16 carbon atoms, and further an olefin oligomer having 3 or 4 carbon atoms. A branched alkyl group having 8 to 16 carbon atoms derived from is more preferable. Specific examples of the olefin having 3 or 4 carbon atoms include propylene, 1-butene, 2-butene, and isobutylene, and propylene or isobutylene is preferable from the viewpoint of excellent solubility. In order to obtain better solubility, R ¹ is derived from a branched octyl group derived from a dimer of isobutylene, a branched nonyl group derived from a trimer of propylene, or a trimer of isobutylene. Even more preferred are branched dodecyl groups, branched dodecyl groups derived from propylene tetramers or branched pentadecyl groups derived from propylene pentamers, and branched derived from isobutylene dimers. An octyl group, a branched dodecyl group derived from a trimer of isobutylene, or a branched dodecyl group derived from a tetramer of propylene is particularly preferred.

  As phenyl-α-naphthylamine represented by the general formula (2), a commercially available product may be used, or a synthetic product may be used. The synthesized product is a reaction between phenyl-α-naphthylamine and a halogenated alkyl compound having 1 to 16 carbon atoms, or phenyl-α-naphthylamine and an olefin or carbon number having 2 to 16 carbon atoms, using a Friedel-Crafts catalyst. It can be easily synthesized by reacting with 2 to 16 olefin oligomers. Specific examples of Friedel-Crafts catalysts include metal halides such as aluminum chloride, zinc chloride, and iron chloride; acidic catalysts such as sulfuric acid, phosphoric acid, phosphorus pentoxide, boron fluoride, acidic clay, and activated clay. Etc. can be used.

  As the alkylated diphenylamine compound, p, p'-dialkyldiphenylamine represented by the following general formula (3) is preferably used.

［式（３）中、Ｒ^２及びＲ^３は同一でも異なっていてもよく、それぞれ炭素数１〜１６のアルキル基を示す。］

[In Formula (3), R ² and R ³ may be the same or different and each represents an alkyl group having 1 to 16 carbon atoms. ]

Specific examples of the alkyl group represented by R ² and R ³ include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, and undecyl. Group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group and the like (these alkyl groups may be linear or branched). Among these, a branched alkyl group having 3 to ¹⁶ carbon atoms is preferable as R ¹⁵ and R ¹⁶ from the viewpoint that antioxidant properties at high temperatures can be maintained for a longer period, and an olefin or oligomer thereof having 3 or 4 carbon atoms. A branched alkyl group having 3 to 16 carbon atoms derived from is more preferable. Specific examples of the olefin having 3 or 4 carbon atoms include propylene, 1-butene, 2-butene, and isobutylene. From the viewpoint that the antioxidant property at a high temperature can be maintained for a longer period, propylene or isobutylene is used. preferable. In addition, R ² or R ³ is derived from an isopropyl group derived from propylene, a tert-butyl group derived from isobutylene, or a dimer of propylene, since further excellent antioxidant properties can be obtained. Branched hexyl group, branched octyl group derived from dimer of isobutylene, branched nonyl group derived from propylene trimer, branched dodecyl group derived from isobutylene trimer, propylene 4 Even more preferred are branched dodecyl groups derived from dimers or branched pentadecyl groups derived from pentamers of propylene, tert-butyl groups derived from isobutylene, branches derived from dimers of propylene Hexyl group, branched octyl group derived from isobutylene dimer, branched nonyl derived from propylene trimer , A branched dodecyl group derived from a tetramer of branched dodecyl or propylene derived from a trimer of isobutylene being most preferred.

When a compound in which one or both of R ² and R ³ are hydrogen atoms is used, sludge may be generated due to oxidation of the compound itself. Moreover, when the number of carbon atoms of the alkyl group exceeds 16, the proportion of the functional group in the molecule becomes small, and the antioxidant property at high temperature may be lowered.

  As the p, p'-dialkyldiphenylamine represented by the general formula (3), a commercially available product may be used, or a synthesized product may be used. The synthesized product uses a Friedel-Crafts catalyst, reaction of diphenylamine, a C1-C16 halogenated alkyl compound and diphenylamine, or diphenylamine and a C2-C16 olefin, a C2-C16 olefin, or these It can be easily synthesized by reacting with the above oligomer. As the Friedel-Crafts catalyst, metal halides and acidic catalysts exemplified in the description of phenyl-α-naphthylamine are used.

  Both the phenyl-α-naphthylamine compound and the alkylated diphenylamine compound are aromatic amines. These aromatic amines may be used singly or as a mixture of two or more different structures. However, since the antioxidant property at a high temperature can be maintained for a longer period, phenyl-α- It is preferable to use a naphthylamine compound and an alkylated diphenylamine compound in combination. The mixing ratio in this case is arbitrary, but the ratio of the alkylated diphenylamine compound to the total of the phenyl-α-naphthylamine compound and the alkylated diphenylamine compound is 0.1 to 0.9 by mass ratio. Preferably, it is 0.1 to 0.4, more preferably 0.15 to 0.35, and particularly preferably 0.2 to 0.3.

  As the phenol compound, any alkylphenol compound used as an antioxidant for lubricating oil can be used, and is not particularly limited. For example, the following general formula (4), general formula (5), and general formula Preferable examples include at least one alkylphenol compound selected from the compounds represented by formula (6). Among these, the alkylphenol compound represented by the general formula (5) is particularly preferable from the viewpoint of solubility in the lubricating base oil.

［式（４）中、Ｒ^４は炭素数１〜４のアルキル基を示し、Ｒ^５は水素原子又は炭素数１〜４のアルキル基を示し、Ｒ^６は水素原子、炭素数１〜４のアルキル基、下記一般式（ｉ）又は（ｉｉ）：

（一般式（ｉ）中、Ｒ^７は炭素数１〜６のアルキレン基を示し、Ｒ^８は炭素数１〜２４のアルキル基又はアルケニル基を示す。）

（一般式（ｉｉ）中、Ｒ^８は炭素数１〜６のアルキレン基を示し、Ｒ^１０は炭素数１〜４のアルキル基を示し、Ｒ^１１は水素原子又は炭素数１〜４のアルキル基を示し、ｋは０又は１を示す。）
で表される基を示す。］

［一般式（５）中、Ｒ^１２及びＲ^１４は同一でも異なっていてもよく、それぞれ炭素数１〜４のアルキル基を示し、Ｒ^１３及びＲ^１５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１〜４のアルキル基を示し、Ｒ^１６及びＲ^１７は同一でも異なっていてもよく、それぞれ炭素数１〜６のアルキレン基を示し、Ａは炭素数１〜１８のアルキレン基又は下記の一般式（ｉｉｉ）：
−Ｒ^１８−Ｓ−Ｒ^１９− （ｉｉｉ）
（一般式（ｉｉｉ）中、Ｒ^１８及びＲ^１９は同一でも異なっていてもよく、それぞれ炭素数１〜６のアルキレン基を示す）
で表される基を示す。］

[In Formula (4), R ⁴ represents an alkyl group having 1 to 4 carbon atoms, R ⁵ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ⁶ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. An alkyl group, the following general formula (i) or (ii):

(In general formula (i), R ⁷ represents an alkylene group having 1 to 6 carbon atoms, and R ⁸ represents an alkyl group or alkenyl group having 1 to 24 carbon atoms.)

(In General Formula (ii), R ⁸ represents an alkylene group having 1 to 6 carbon atoms, R ¹⁰ represents an alkyl group having 1 to 4 carbon atoms, and R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. And k represents 0 or 1.)
The group represented by these is shown. ]

[In General Formula (5), R ¹² and R ¹⁴ may be the same or different and each represents an alkyl group having 1 to 4 carbon atoms; R ¹³ and R ¹⁵ may be the same or different; Represents an atom or an alkyl group having 1 to 4 carbon atoms, R ¹⁶ and R ¹⁷ may be the same or different, each represents an alkylene group having 1 to 6 carbon atoms, and A represents an alkylene group having 1 to 18 carbon atoms or The following general formula (iii):
—R ¹⁸ —S—R ¹⁹ — (iii)
(In general formula (iii), R ¹⁸ and R ¹⁹ may be the same or different and each represents an alkylene group having 1 to 6 carbon atoms)
The group represented by these is shown. ]

［一般式（６）中、Ｒ^２０は炭素数１〜４のアルキル基を示し、Ｒ^２１は水素原子又は炭素数１〜４のアルキル基を示し、Ｒ^２２は炭素数１〜６のアルキレン基又は下記一般式（ｉｖ）：

（一般式（ｉｖ）中、Ｒ^２３及びＲ^２４は同一でも異なっていてもよく、それぞれ炭素数１〜６のアルキレン基を示す。）
で表される基を示す。］

[In General Formula (6), R ²⁰ represents an alkyl group having 1 to 4 carbon atoms, R ²¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R ²² represents an alkylene group having 1 to 6 carbon atoms. Or the following general formula (iv):

(In general formula (iv), R ²³ and R ²⁴ may be the same or different and each represents an alkylene group having 1 to 6 carbon atoms.)
The group represented by these is shown. ]

In the compound represented by the general formula (4), when R ⁶ is a group represented by the general formula (i), R ⁷ in the general formula (i) is an alkylene group having 1 to 2 carbon atoms. R ⁸ is more preferably a linear or branched alkyl group having 6 to 12 carbon atoms, R ^{7 in the} general formula (i) is an alkylene group having 1 to 2 carbon atoms, and R ⁸ Is particularly preferably a branched alkyl group having 6 to 12 carbon atoms.

  Preferred compounds among the compounds represented by formula (5) are shown below.

Examples of the compound when R ⁶ is an alkyl group having 1 to 4 carbon atoms include 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butyl-4-ethylphenol, etc. Can be mentioned.

Examples of the compound when R ⁶ is a group represented by the general formula (i) include the following. N-hexyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, isohexyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3-methyl-5-tert-butyl) -4-hydroxyphenyl) acetic acid n-heptyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isoheptyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate n-octyl Isooctyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, 2-ethylhexyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate, (3-methyl-5-tert- Butyl-4-hydroxyphenyl) acetic acid n-nonyl, (3-methyl-5-tert-butyl-4 Hydroxyphenyl) isononyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetate n-decyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isodecyl acetate, (3-methyl -5-tert-butyl-4-hydroxyphenyl) acetic acid n-undecyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) acetoisodecyl, (3-methyl-5-tert-butyl-4-hydroxy) Phenyl) acetate n-dodecyl, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isododecyl acetate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate n-hexyl, (3 -Methyl-5-tert-butyl-4-hydroxyphenyl) propionic acid Hexyl, n-heptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, isoheptyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5 -Tert-butyl-4-hydroxyphenyl) n-octylpropionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isooctylpropionate, (3-methyl-5-tert-butyl-4-hydroxy) 2-ethylhexyl (phenyl) propionate, n-nonyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, isononyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-tert-butyl-4-hydroxyl N-decyl propionate, (3-methyl-5-tert-butyl-4-hydroxyphenyl) isodecyl propionate, n-undecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, Isoundecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, n-dodecyl (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, (3-methyl-5-tert -Butyl-4-hydroxyphenyl) isododecyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate n-hexyl, (3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid Isohexyl, (3,5-di-tert-butyl-4-hydroxyphenyl N-heptyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) isoheptyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate n-octyl, (3,5- Di-tert-butyl-4-hydroxyphenyl) isooctyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetic acid 2-ethylhexyl, (3,5-di-tert-butyl-4-hydroxyphenyl) ) N-nonyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) isononyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate n-decyl, (3,5 -Di-tert-butyl-4-hydroxyphenyl) isodecyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) N-undecyl acid, (3,5-di-tert-butyl-4-hydroxyphenyl) isoundecyl acetate, (3,5-di-tert-butyl-4-hydroxyphenyl) acetate n-dodecyl, (3,5- Di-tert-butyl-4-hydroxyphenyl) isododecyl acetate, n-hexyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert-butyl-4-hydroxy) (Phenyl) isohexylpropionate, (3,5-di-tert-butyl-4-hydroxyphenyl) n-heptylpropionate, (3,5-di-tert-butyl-4-hydroxyphenyl) isoheptylpropionate, (3 , 5-Di-tert-butyl-4-hydroxyphenyl) propionate n-octyl, (3,5-di- tert-butyl-4-hydroxyphenyl) isooctylpropionate, 2-ethylhexyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) ) N-nonyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) isononyl propionate, (3,5-di-tert-butyl-4-hydroxyphenyl) n-decyl propionate, ( Isodecyl 3,5-di-tert-butyl-4-hydroxyphenyl) propionate, n-undecyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, (3,5-di-tert- Butyl-4-hydroxyphenyl) isoundecyl propionate, (3,5-di-tert Butyl-4-hydroxyphenyl) propionic acid n- dodecyl, and (3,5-di -tert- butyl-4-hydroxyphenyl) isododecyl propionate.

Examples of the compound when R ⁶ is a group represented by the general formula (ii) include bis (3,5-di-tert-butyl-4-hydroxyphenyl), bis (3,5-di-tert). -Butyl-4-hydroxyphenyl) methane, 1,1-bis (3,5-di-tert-butyl-4-hydroxyphenyl) ethane, 1,2-bis (3,5-di-tert-butyl-4) -Hydroxyphenyl) ethane, 1,1-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane, 1,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) Propane, 1,3-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane, 2,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane and the like; and This A mixture of two or more of these may be used.

  Next, the alkylphenol represented by the general formula (5) will be described.

  A particularly preferable compound when A in the general formula (5) is an alkylene group having 1 to 18 carbon atoms is a compound represented by the following formula (5-1).

  A particularly preferred compound when A in the general formula (5) is a group represented by the formula (iii) is a compound represented by the following formula (5-2).

  Next, the alkylphenol represented by the general formula (6) will be described.

  Specifically preferred as the alkylphenol represented by the general formula (6) is a compound represented by the following formula (6-1) or (6-2).

  The content of the ashless antioxidant that does not contain sulfur as a constituent element is 0.3 to 5% by mass, preferably 0.3 to 3% by mass, more preferably 0.8%, based on the total amount of the composition. 4 to 2% by mass. When the content of the ashless antioxidant is less than 0.3% by mass, the heat / oxidation stability and sludge suppression tend to be insufficient. On the other hand, if it exceeds 5% by mass, the effects of heat / oxidation stability and sludge suppression suitable for the content cannot be obtained, and this is disadvantageous economically, which is not preferable.

  The lubricating oil composition of the present invention may be composed only of the above-mentioned lubricating base oil and ashless antioxidant, but from the point that thermal and oxidation stability and sludge suppression can be further improved, It is preferable to further contain an alkyl group-substituted aromatic hydrocarbon compound.

  In the present invention, it is preferable to use at least one selected from alkylbenzene, alkylnaphthalene, alkylbiphenyl, and alkyldiphenylalkane as the alkyl group-substituted aromatic hydrocarbon compound.

  Specific examples of the alkyl group of alkylbenzene include, for example, methyl group, ethyl group, propyl group (including all isomers), butyl group (including all isomers), and pentyl group (all isomers). ), Hexyl group (including all isomers), heptyl group (including all isomers), octyl group (including all isomers), nonyl group (including all isomers), decyl group (including all isomers) All isomers included, undecyl group (including all isomers), dodecyl group (including all isomers), tridecyl group (including all isomers), tetradecyl group (including all isomers) ), Pentadecyl group (including all isomers), hexadecyl group (including all isomers), heptadecyl group (including all isomers), octadecyl group (all isomers) ), Nonadecyl group (including all isomers), icosyl group (including all isomers), heicosyl group (including all isomers), docosyl group (including all isomers), tricosyl group (including All isomers included, tetracosyl group (including all isomers), pentacosyl group (including all isomers), hexacosyl group (including all isomers), heptacosyl group (including all isomers) ), Octacosyl group (including all isomers), nonacosyl group (including all isomers), triacontyl group (including all isomers), hentriacontyl group (including all isomers), dotriacontyl group (Including all isomers), tritriacontyl group (including all isomers), tetratriacontyl group (including all isomers), pen Triacontyl group (including all isomers), hexatriacontyl group (including all isomers), heptatriacontyl group (including all isomers), octatriacontyl group (including all isomers) Alkyl group having 1 to 40 carbon atoms such as nonatriacontyl group (including all isomers) and tetracontyl group (including all isomers). Among these, it has 1 to 4 (more preferably 1 to 2) alkyl groups having 8 to 30 carbon atoms, and the total carbon number of the alkyl groups is 10 to 50 (more preferably 20 to 40). Certain alkyl benzenes are preferably used.

  The alkyl group of the alkylbenzene may be linear or branched, but a branched alkyl group is preferable from the viewpoint of stability, viscosity characteristics, etc., and propylene is particularly preferable from the viewpoint of availability. More preferred are branched alkyl groups derived from oligomers of olefins such as butene and isobutylene.

  The number of alkyl groups in the alkylbenzene is preferably 1 to 4, but from the viewpoint of stability and availability, alkylbenzene having one or two alkyl groups, that is, monoalkylbenzene, dialkylbenzene, or these Mixtures are most preferably used.

  Said alkylbenzene may be used individually by 1 type, and may be used as a 2 or more types of mixture. When using the mixture of 2 or more types of alkylbenzene, it is preferable that the average molecular weight of the said mixture is 200-500.

  The production method of alkylbenzene is arbitrary and is not limited at all, but can be generally produced by the synthesis method shown below. Specific examples of the aromatic hydrocarbon compound used as a raw material include benzene, toluene, xylene, ethylbenzene, methylethylbenzene, diethylbenzene, and mixtures thereof. The alkylating agent is specifically a lower monoolefin such as ethylene, propylene, butene and isobutylene, preferably a linear or branched olefin having 6 to 40 carbon atoms obtained by polymerization of propylene; Linear or branched olefins having 6 to 40 carbon atoms obtained by thermal decomposition of wax, heavy oil, petroleum fraction, polyethylene, polypropylene, etc .; n-paraffins are separated from petroleum fractions such as kerosene and light oil C6-C40 linear olefin obtained by olefination with a catalyst; and mixtures thereof can be used.

  In addition, as alkylation catalysts in the alkylation, Friedel-Crafts type catalysts such as aluminum chloride and zinc chloride; acidic catalysts such as sulfuric acid, phosphoric acid, silicotungstic acid, hydrofluoric acid, activated clay, etc. A known catalyst is used.

  As the alkylnaphthalene, a compound represented by the following general formula (7) is preferably used.

［式（７）中、Ｒ^２５、Ｒ^２６、Ｒ^２７及びＲ^２８は同一でも異なっていても良く、それぞれ水素原子又は炭素数１〜４０の炭化水素基を示し、Ｒ^２５、Ｒ^２６、Ｒ^２７又はＲ^２８の少なくとも１つはアルキル基である。］

[In Formula (7), R ²⁵ , R ²⁶ , R ²⁷ and R ²⁸ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 40 carbon atoms, and R ²⁵ , R ²⁶ , R ^At least one of ²⁷ or R ²⁸ is an alkyl group. ]

R ²⁵ , R ²⁶ , R ²⁷ and R ²⁸ in the general formula (7) each represent a hydrogen atom or a hydrocarbon group. The hydrocarbon group includes an alkyl group, an alkenyl group, an aryl group, and an alkylaryl group. R ²⁵ , R ²⁶ , R ²⁷ and R ²⁸ are all preferably alkyl groups.

  As an alkyl group, what was illustrated as an alkyl group which alkylbenzene has in description of the said alkylbenzene is mentioned. Among these, an alkyl group having 8 to 30 carbon atoms is preferable, and an alkyl group having 10 to 20 carbon atoms is more preferable.

In the alkylnaphthalene represented by the general formula (7), R ²⁵ , R ²⁶ , R ²⁷ and R ²⁸ may be the same or different. That is, R ²⁵ , R ²⁶ , R ²⁷ and R ²⁸ may all be hydrocarbon groups containing an alkyl group, or at least one of R ²⁵ , R ²⁶ , R ²⁷ or R ²⁸ is an alkyl group May be a hydrogen atom. The total carbon number of R ²⁵ , R ²⁶ , R ²⁷ and R ²⁸ is preferably 8 to 50, more preferably 10 to 40.

When two or more of R ²⁵ , R ²⁶ , R ²⁷ or R ²⁸ are hydrocarbon groups, the combination is arbitrary as long as at least one of them is an alkyl group, but all of them are preferably alkyl groups. Further, two hydrocarbon groups may be bonded to the same benzene ring such that R ²⁵ and R ²⁶ are hydrocarbon groups, and R ²⁵ and R ²⁷ are hydrocarbon groups. Alternatively, one having one hydrocarbon group bonded to each of different benzene rings may be used.

  Specific examples of the alkylnaphthalene represented by the general formula (7) include decylnaphthalene (including all isomers), undecylnaphthalene (including all isomers), dodecylnaphthalene (all isomers). ), Tridecylnaphthalene (including all isomers), tetradecylnaphthalene (including all isomers), pentadecylnaphthalene (including all isomers), hexadecylnaphthalene (including all isomers) , Heptadecylnaphthalene (including all isomers), octadecylnaphthalene (including all isomers), nonadecylnaphthalene (including all isomers), icosylnaphthalene (including all isomers), di ( Decyl) naphthalene (including all isomers), di (undecyl) naphthalene (including all isomers) , Di (dodecyl) naphthalene (including all isomers), di (tridecyl) naphthalene (including all isomers), di (tetradecyl) naphthalene (including all isomers), di (pentadecyl) naphthalene (all ), Di (hexadecyl) naphthalene (including all isomers), di (heptadecyl) naphthalene (including all isomers), di (octadecyl) naphthalene (including all isomers), di (Nonadecyl) naphthalene (including all isomers), di (icosyl) naphthalene (including all isomers), and the like.

  Among these, alkyl naphthalene having 1 to 4 (more preferably 1 to 2) alkyl groups having 8 to 30 carbon atoms (more preferably 10 to 20 carbon atoms) is preferable, and the total of alkyl groups possessed by alkyl naphthalene. The carbon number is preferably 8 to 50 (more preferably 10 to 40).

  Said alkyl naphthalene may be used individually by 1 type, and may be used as a 2 or more types of mixture. When using the mixture of 2 or more types of alkyl naphthalene, it is preferable that the average molecular weight of the said mixture is 200-500.

  Alkylnaphthalene can be produced by any method and can be produced by various known methods. Examples of this include hydrocarbon halides, olefins, styrenes, etc., mineral acids such as sulfuric acid, phosphoric acid, silicotungstic acid, hydrofluoric acid, solid acidic substances such as acidic clay, activated clay, and aluminum chloride And a method of adding to naphthalene in the presence of an acid catalyst such as a Friedel-Crafts catalyst which is a metal halide such as zinc chloride.

  As the alkylbiphenyl, a compound represented by the following general formula (8) is preferably used.

［式（８）中、Ｒ^２９、Ｒ^３０、Ｒ^３１及びＲ^３２は同一でも異なっていても良く、それぞれ水素原子又は炭素数１〜４０の炭化水素基を示し、Ｒ^２９、Ｒ^３０、Ｒ^３１又はＲ^３２のうち少なくとも１つはアルキル基である。］

[In the formula (8), R ²⁹ , R ³⁰ , R ³¹ and R ³² may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 40 carbon atoms, and R ²⁹ , R ³⁰ , R ^At least one of ³¹ or R ³² is an alkyl group. ]

Examples of the hydrocarbon group represented by R ²⁹ , R ³⁰ , R ³¹ and R ³² in the general formula (8) include an alkenyl group, an aryl group, an alkaryl group, an aralkyl group and the like in addition to an alkyl group. R ²⁹ , R ³⁰ , R ³¹ and R ³² are preferably all alkyl groups.

  As an alkyl group, what was illustrated as an alkyl group which alkylbenzene has in description of the said alkylbenzene is mentioned. Among these, an alkyl group having 8 to 30 carbon atoms is preferable, and an alkyl group having 10 to 20 carbon atoms is more preferable.

In the alkylbiphenyl represented by the general formula (8), R ²⁹ , R ³⁰ , R ³¹ and R ³² may be the same or different. That is, R ²⁹ , R ³⁰ , R ³¹ and R ³² may be all alkyl groups, or at least one of R ²⁹ , R ³⁰ , R ³¹ or R ³² is an alkyl group and the others are hydrogen atoms or alkyls. It may be a hydrocarbon group other than the group. The total carbon number of R ²⁹ , R ³⁰ , R ³¹ and R ³² is preferably 8 to 50, more preferably 10 to 40.

When two or more of R ²⁹ , R ³⁰ , R ³¹ or R ³² are hydrocarbon groups, the combination is arbitrary as long as at least one of them is an alkyl group, and R ²⁹ and R ³⁰ are hydrocarbon groups. Two hydrocarbon groups may be bonded to the same benzene ring, and one hydrocarbon is provided for each different benzene ring such that R ²⁹ and R ³¹ are hydrocarbon groups. A group to which a group is bonded may be used.

  Said alkyl biphenyl may be used individually by 1 type, and may be used as a 2 or more types of mixture. When a mixture of two or more alkylbiphenyls is used, the average molecular weight of the mixture is preferably 200 to 500.

  The production method of alkylbiphenyl is arbitrary, and can be produced by various known methods. Examples of this include hydrocarbon halides, olefins, styrenes, etc., mineral acids such as sulfuric acid, phosphoric acid, silicotungstic acid, hydrofluoric acid, solid acidic substances such as acidic clay, activated clay, and aluminum chloride And a method of adding to biphenyl in the presence of an acid catalyst such as a Friedel-Crafts catalyst which is a metal halide such as zinc chloride.

  As the alkyldiphenylalkane, a compound represented by the following general formula (9) is preferably used.

［式（９）中、Ｒ^３３、Ｒ^３４、Ｒ^３５及びＲ^３６は同一でも異なっていても良く、それぞれ水素原子又は炭素数１〜４０の炭化水素基を示し、Ｒ^３３、Ｒ^３４、Ｒ^３５又はＲ^３６のうち少なくとも１つはアルキル基であり、Ｒ^３７は炭素数１〜８のアルキレン基またはアルケニレン基を示す。］

[In the formula (9), R ³³ , R ³⁴ , R ³⁵ and R ³⁶ may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 1 to 40 carbon atoms, and R ³³ , R ³⁴ , R ^At least one of ³⁵ or R ³⁶ is an alkyl group, and R ³⁷ represents an alkylene group having 1 to 8 carbon atoms or an alkenylene group. ]

Examples of the hydrocarbon group represented by R ³³ , R ³⁴ , R ³⁵ and R ³⁶ in the general formula (9) include an alkenyl group, an aryl group, an alkaryl group, an aralkyl group and the like in addition to an alkyl group. R ³³ , R ³⁴ , R ³⁵ and R ³⁶ are preferably all alkyl groups.

  As an alkyl group, what was illustrated as an alkyl group which alkylbenzene has in description of the said alkylbenzene is mentioned. Among these, an alkyl group having 8 to 30 carbon atoms is preferable, and an alkyl group having 10 to 20 carbon atoms is more preferable.

In the diphenylalkane represented by the general formula (9), R ³³ , R ³⁴ , R ³⁵ and R ³⁶ may be the same or different. That is, R ³³ , R ³⁴ , R ³⁵ and R ³⁶ may be all alkyl groups, or at least one of R ³³ , R ³⁴ , R ³⁵ or R ³⁶ is an alkyl group and the other is a hydrogen atom or an alkyl group. It may be a hydrocarbon group other than the group. The total carbon number of R ³³ , R ³⁴ , R ³⁵ and R ³⁶ is preferably 8 to 50, more preferably 10 to 40.

When two or more of R ³³ , R ³⁴ , R ³⁵ and R ³⁶ are hydrocarbon groups, the combination is arbitrary as long as at least one of them is an alkyl group, and R ³³ and R ³⁴ are hydrocarbon groups. There may be two hydrocarbon groups bonded to the same benzene ring, or one hydrocarbon on each of the different benzene rings where R ³³ and R ³⁵ are hydrocarbon groups. A group to which a group is bonded may be used.

Further, ^{R 37} in the general formula (9) represents an alkylene group or an alkenylene group. Specific examples of R ³⁷ include a methylene group; a methylmethylene group (ethylidene group), an alkylene group having 2 carbon atoms such as an ethylene group; an ethylmethylene group (propylidene group), a dimethylmethylene group (isopropylidene group), An alkylene group having 3 carbon atoms such as methylethylene group (propylene group) and trimethylene group; n-propylmethylene group (butylidene group), isopropylmethylene group (isobutylidene group), ethylmethylmethylene group, ethylethylene group, 1,1- Alkylene groups having 4 carbon atoms such as dimethylethylene group, 1,2-dimethylethylene group, 1-methyltrimethylene group, 2-methyltrimethylene group, tetramethylene group; n-butylmethylene group (pentylidene group), sec- Butylmethylene group, isobutylmethylene group (isopentylidene group), ter t-butylmethylene group, n-propylmethylmethylene group, isopropylmethylmethylene group, diethylmethylene group, n-propylethylene group, isopropylethylene group, 1-ethyl-1-methylethylene group, 1-ethyl-2-methylethylene Group, trimethylethylene group, 1-ethyltrimethylene group, 2-ethyltrimethylene group, 1,1-dimethyltrimethylene group, 1,2-dimethyltrimethylene group, 1,3-dimethyltrimethylene group, 2,2 -C 5 alkylene group such as dimethyltrimethylene group, 1-methyltetramethylene group, 2-methyltetramethylene group, pentamethylene group; n-pentylmethylene group (hexylidene group), (1-methylbutyl) methylene group, Isopentylmethylene group (isopentylidene group), (1,2-dimethylpropyl) Methylene group, n-butylmethylmethylene group, isobutylmethylmethylene group, ethyl-n-propylmethylene group, ethylisopropylmethylene group, butylethylene group, isobutylmethylene group, 1- (n-propyl) -1-methylethylene group, 1- (n-propyl) -2-methylethylene group, 1-isopropyl-1-methylethylene group, 1-isopropyl-2-methylethylene group, 1,2-diethylethylene group, 1-ethyl-2,2- Dimethylethylene group, tetramethylethylene group, 1-n-propyltrimethylene group, 2-n-propyltrimethylene group, 1-isopropyltrimethylene group, 2-isopropyltrimethylene group, 1-ethyl-3-methyltrimethylene Group, 1-ethyl-2-methyltrimethylene group, 1,1,2-trimethyltrimethyl Group, 1,1,3-trimethyltrimethylene group, 1-ethyltetramethylene group, 1,1-dimethyltetramethylene group, 1,3-dimethyltetramethylene group, 1,4-dimethyltetramethylene group, 2, Alkylene group having 6 carbon atoms such as 2-dimethyltetramethylene group, 1-methylpentamethylene group, 2-methylpentamethylene group and hexamethylene group (including all isomers of alkylene groups having 6 carbon atoms); n- C7 alkylene groups (including isomers of all C7 alkylene groups) such as hexylmethylene group (heptylidene group) and n-pentylethylene group (heptylene group); n-heptylmethylene group (octylidene group) , N-hexylethylene group (octylene group) and other C8 alkylene groups (including all isomers of C8 alkylene groups) An alkenylene group having 2 carbon atoms such as vinylidene group and ethenylene group (vinylene group); an alkenylene group having 3 carbon atoms such as propenylene group, methyleneethylene group, methylethenylene group, 1-propenylidene group and 2-propenylidene group; 3 -Alkenylene group having 4 carbon atoms such as methylpropenylene group (including all isomers of alkenylene group having 4 carbon atoms); 1-methyl-3-methylenetrimethylene group, 3-ethylpropenylene group, 1,3 -Alkenylene groups having 5 carbon atoms such as dimethylpropenylene group, 2,3-dimethylpropenylene group, 3,3-dimethylpropenylene group (including all isomers of alkenylene groups having 5 carbon atoms); 1,1 -Dimethyl-3-methylenetrimethylene group, 1-ethyl-3-methylenetrimethylene group, 3-ethyl-1-methylpropenylene group 6-alkenylene groups such as 3-ethyl-2-methylpropenylene group, 1,3,3-trimethylpropenylene group, 2,3,3-trimethylpropenylene group (all of the alkenylene groups having 6 carbon atoms) Including isomers); alkenylene groups having 7 carbon atoms such as heptenylene groups (including isomers of all alkenylene groups having 7 carbon atoms); alkenylene groups having 8 carbon atoms such as octenylene groups (all alkenylene having 8 carbon atoms) Group isomers) and the like.

The R ^37, preferably an alkylene or alkenylene group having 1 to 8 carbon atoms, more preferably an alkylene group and alkenylene group of 1 to 6 carbon atoms. Particularly preferred are carbons such as methylene, methylmethylene (ethylidene), ethylene, ethylmethylene (propylidene), dimethylmethylene (isopropylidene), methylethylene (propylene), trimethylene, etc. An alkylene group having 1 to 3 carbon atoms; an alkenylene group having 2 to 3 carbon atoms such as a vinylidene group, an ethenylene group (vinylene group), a propenylene group, a methyleneethylene group, a methylethenylene group, a 1-propenylidene group, and a 2-propenylidene group; Among alkylene groups having 4 to 6 carbon atoms, 1-methyltrimethylene group, 1-ethyltrimethylene group, 1,1-dimethyltrimethylene group, 1,2-dimethyltrimethylene group, 1,3-dimethyltrimethylene group Group, 1-ethyl-3-methyltrimethylene group, 1-ethyl-2-methyltrimethyl Among 1,4,6-trimethyltrimethylene group, 1,4-trimethyltrimethylene group; and alkenylene groups having 4 to 6 carbon atoms, 3-methylpropenylene group, 1-methyl-3- Methylenetrimethylene, 3-ethylpropenylene, 1,3-dimethylpropenylene, 2,3-dimethylpropenylene, 3,3-dimethylpropenylene, 1,1-dimethyl-3-methylenetrimethylene Group, 1-ethyl-3-methylenetrimethylene group, 3-ethyl-1-methylpropenylene group, 3-ethyl-2-methylpropenylene group, 1,3,3-trimethylpropenylene group, 2,3, 3-trimethylpropenylene group; etc. are mentioned.

  Said diphenylalkane may be used individually by 1 type, and may be used as a 2 or more types of mixture. When using the mixture of 2 or more types of diphenylalkane, it is preferable that the average molecular weights of the said mixture are 200-500.

  The production method of diphenylalkane is arbitrary, and can be produced by various known methods. Some examples are shown below.

  For example, diphenylalkane can be obtained by adding styrenes such as styrene, α-, β-methylstyrene, and ethylstyrene to alkylbenzene in the presence of an acid catalyst. Examples of the acid catalyst that can be used include mineral acids such as sulfuric acid and phosphoric acid, solid acidic substances such as acidic clay and activated clay, and Friedel-Crafts catalysts that are metal halides.

  Alkyldiphenylalkane is also produced by the polymerization reaction of the above styrenes in the presence of a suitable acid catalyst. At this time, a single styrene compound may be used, or two or more styrene compounds may be copolymerized. Examples of the acid catalyst that can be used include mineral acids such as sulfuric acid and phosphoric acid, solid acidic substances such as acidic clay and activated clay, and Friedel-Crafts catalysts that are metal halides. Usually, the hydrocarbon compound obtained by this method is a compound in which two benzene rings are bonded by an alkenylene group, but in the present invention, it may be used as it is, or hydrogenation of an alkenylene group in the presence of a suitable catalyst. You may use the compound which processed and converted the alkenylene group into the alkylene group.

  Regarding alkylation of aromatic hydrocarbon compounds, the Friedel-Crafts reaction of chloride is well known, but diphenylalkanes can also be produced by this method. For example, the hydrocarbon compound according to the present invention can be obtained by reacting an alkylbenzene having a chlorinated side chain alkyl group with benzene or an alkylbenzene in the presence of a suitable Friedel-Crafts catalyst such as a metal halide. In addition, there is a method of coupling a dihalogenated alkane and benzene or alkylbenzene in the presence of a suitable Friedel-Crafts catalyst such as a metal halide.

Alkyl diphenyl alkane, R ³³ using the alkylbenzene having an alkyl group represented may be manufactured in the manner such as by ~R ^36, R ³³ ~R ³⁶ to diphenylalkane produced by the above methods, etc. It can also be produced by adding an alkyl group represented by the following methods.

  In the present invention, as the aromatic hydrocarbon compound having an alkyl group, one of alkylbenzene, alkylnaphthalene, alkylbiphenyl and alkyldiphenylalkane described above may be used alone, or two or more may be combined. . Among these, alkylbenzene or alkylnaphthalene is particularly preferable, and alkylnaphthalene is most preferable because it is excellent in the effect of improving sludge suppression.

The viscosity of the alkyl-substituted aromatic hydrocarbon compound used in the present invention is not particularly limited, kinematic viscosity at 40 ° C. is preferably 10 to 100 mm ² / s, more preferably 20 to 80 mm ² / s, further Preferably it is 25-60 mm < ² > / s.

  When the lubricating oil composition of the present invention contains an alkyl group-substituted aromatic hydrocarbon compound, the content of the alkyl group-substituted aromatic hydrocarbon compound is determined from the viewpoint of heat / oxidation stability and sludge suppression. Based on the total amount, it is preferably 2% by mass or more, more preferably 5% by mass or more, and further preferably 10% by mass or more. From the viewpoint of viscosity-temperature characteristics, the content of the alkyl group-substituted aromatic hydrocarbon compound is preferably 50% by mass or less, more preferably 30% by mass or less, based on the total amount of the composition. The content is more preferably 20% by mass or less, and particularly preferably 15% by mass or less.

  The lubricating oil composition of the present invention further includes other known lubricating oil additives such as a rust inhibitor, a corrosion inhibitor, a pour point depressant, an antifoaming agent, etc. for the purpose of further enhancing various performances. You may contain. These additives may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the rust inhibitor include aliphatic amines, organic sulfonic acid metal salts, organic phosphoric acid metal salts, alkenyl succinic acid esters, polyhydric alcohol esters, and the like.

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

  Examples of the antifoaming agent include silicones such as dimethyl silicone, polyacrylate compounds, and the like.

  The content of these additives can be arbitrarily selected, but the content of each additive is 0.01 to 5% by mass in the case of a pour point depressant, rust inhibitor and corrosion based on the total amount of the composition. In the case of an inhibitor, it is preferably 0.01 to 3% by mass, and in the case of an antifoaming agent, it is preferably 0.00001 to 0.05% by mass.

  The lubricating oil composition of the present invention having the above-mentioned configuration can achieve a high level of thermal / oxidation stability and sludge suppression, and is very useful as a lubricating oil composition for high temperature applications. Here, regarding the high temperature application, the use temperature is not particularly limited, but is preferable because the above-described effect of the present invention is exhibited at a high level when the oil temperature of the tank used for circulation is continuously 60 ° C. or higher. Furthermore, it is more preferable because an excellent effect is exhibited when the temperature is 80 ° C. or higher, and particularly preferable when the temperature is 100 ° C. or higher because a further excellent effect is exhibited. Examples of such high-temperature applications include large-capacity steam turbines, gas turbines that use combustion gas of LNG and steelworks by-product gas as a working medium, various rotary gas compressors, and construction machines that operate at high temperatures. The use of the lubricating oil composition of the present invention is not limited to these.

  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, 2)
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. The 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, in the presence of a hydrocracking catalyst, WAX1 was hydrocracked under the conditions of a hydrogen partial pressure of 5 MPa, an average reaction temperature of 340 ° C., and LHSV 0.8 hr ⁻¹ . As the hydrocracking catalyst, a catalyst in which nickel and molybdenum were supported on an amorphous silica / alumina carrier was used in a sulfurized state.

    Next, the cracked product obtained by the above hydrocracking was distilled under reduced pressure to obtain a 20% by volume lubricating oil fraction with respect to the raw material oil. This lubricating oil fraction was subjected to solvent dewaxing using a methyl ethyl ketone-toluene mixed solvent under conditions of a solvent / oil ratio of 2 times and a filtration temperature of -30 ° C. 1 ”and“ base oil 2 ”).

(Base oil 3, 4)
700 g of zeolite and 300 g of an alumina binder were mixed and kneaded and molded into a cylindrical shape having a diameter of 1/16 inch (about 1.6 mm) and a height of 8 mm. The obtained molded body was fired at 480 ° C. for 2 hours to obtain a carrier. By impregnating this carrier with an aqueous solution of dichlorotetraamineplatinum (II) in an amount of 1.0% by mass of the carrier in terms of platinum, drying at 125 ° C. for 2 hours, and baking at 380 ° C. for 1 hour, The desired catalyst was obtained.

Next, the obtained catalyst was charged into a fixed bed flow reactor, and hydrocracking / hydroisomerization of feedstock containing paraffinic hydrocarbons was performed using this reactor. In this step, FT wax (hereinafter referred to as “WAX2”) having a paraffin content of 95% by mass and having a carbon number distribution of 20 to 80 was used as the raw material oil. Table 2 shows the properties of WAX2. The hydrocracking conditions were a hydrogen pressure of 3.5 MPa, a reaction temperature of 340 ° C., LHSV 1.5 h ^−1, and a fraction (decomposition product) having a boiling point of 370 ° C. or less with respect to the raw material was 25% by mass (decomposition rate 25 %) Was obtained.

  Next, a lubricating oil fraction was obtained by distillation under reduced pressure of the cracked / isomerized product oil obtained in the hydrocracking / hydroisomerization step. For this lubricating oil fraction, solvent dewaxing was performed using a methyl ethyl ketone-toluene mixed solvent at a solvent / oil ratio of 3 times and a filtration temperature of -30 ° C. , "Base oil 3" and "Base oil 4").

(Base oil 5, 6)
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 “WAX3”) was used as a raw material for the lubricant base oil. Table 3 shows the properties of WAX3.

Next, WAX3 was hydrocracked in the presence of a hydrocracking catalyst under the conditions of a hydrogen partial pressure of 5.5 MPa, an average reaction temperature of 340 ° C., and LHSV 0.8 hr ⁻¹ . As the hydrocracking catalyst, a catalyst in which nickel and molybdenum were supported on an amorphous silica / alumina carrier was used in a sulfurized state.

  Next, the cracked product obtained by the above hydrocracking was distilled under reduced pressure to obtain a 20% by volume lubricating oil fraction with respect to the raw material oil. This lubricating oil fraction was subjected to solvent dewaxing using a methyl ethyl ketone-toluene mixed solvent under conditions of a solvent / oil ratio of 2 times and a filtration temperature of -30 ° C. 5 ”and“ base oil 6 ”).

  Tables 4 and 5 show various properties and performance evaluation test results of the base oils 1 to 6. In addition, Table 6 shows various properties and performance evaluation test results for base oils 7 and 8 which are conventional high viscosity index base oils.

Next, the base oil 1 and the base oil 2 are mixed to prepare a base oil 9 (base oil 1 / base oil 2 = 10/90 (mass ratio), kinematic viscosity at 40 ° C .: 32 mm ² / s). did.

Further, the base oil 3 and the base oil 4 are mixed to obtain a base oil 10 (base oil 3 / base oil 4 = 12/88 (mass ratio), kinematic viscosity at 40 ° C .: 32.1 mm ² / s). Prepared.

The base oil 7 and the base oil 8 were mixed to prepare a base oil 11 (base oil 7 / base oil 8 = 20/80 (mass ratio), kinematic viscosity at 40 ° C .: 32 mm ² / s). .

Furthermore, base oil 12 (poly α-olefin, kinematic viscosity at 40 ° C .: 32.0 mm ² / s) was prepared as a lubricating base oil for comparison.

[Examples 1 to 18, Comparative Examples 1 to 4]
In Examples 1 to 10, lubricating oil compositions having the compositions shown in Tables 7 to 8 were prepared using the above base oil 9 or 10 and the following additives. Moreover, in Examples 11-18, the lubricating oil composition which has a composition shown to Tables 9-10 was prepared using said base oil 6 and the additive shown below. Moreover, in Comparative Examples 1-4, the lubricating oil composition which has a composition shown in Table 11 was prepared using said base oil 11 or base oil 12 and the additive shown below.
(Antioxidant)
A1: (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid ester A2: dodecylphenyl-α-naphthylamine A3: N-octylphenyl-N-butylphenylamine (alkyl group-substituted aromatic hydrocarbon compound) )
B1: Alkylnaphthalene having 1-2 alkyl groups having 16 or 18 carbon atoms.

[Characteristic evaluation test (1)]
About the lubricating oil composition of Examples 1-18 and Comparative Examples 1-4, the characteristic evaluation test which used together the turbine oil oxidation stability test (TOST) prescribed | regulated to JISK2514, and a rotation cylinder type oxidation stability test (RBOT) Carried out. Specifically, in the TOST test, each lubricating oil composition was oxidized and deteriorated at 120 ° C. for a predetermined time, and the sludge generation amount and RBOT value at that time were measured. Based on the time when the RBOT value of the deteriorated oil reaches 25% of the RBOT value before the test (residual life 25% arrival time) and the amount of sludge generated at that time, the thermal and oxidation stability of the lubricating oil composition and Sludge suppression was evaluated. Tables 7 to 11 show the RBOT value of each lubricating oil composition before the test, the remaining life of 25% reaching time, and the amount of sludge produced when the remaining life reached 25% (the amount produced per 100 ml of sample oil).

[Characteristic evaluation test (2)]
About the lubricating oil composition of Examples 1-18 and Comparative Examples 1-4, sludge suppression property was evaluated as follows. With the high-temperature pump circulation test facility shown in FIG. 1, each lubricating oil composition was circulated at 7 MPa and 120 ° C. using a piston pump, and the difference in pressure before and after the line filter (3 μm) set in the circulation system was monitored. . When there is no sludge, the differential pressure is about 35 kPa, but when the sludge is collected, the differential pressure gradually increases. Thus, the operation time until the differential pressure reached 100 kPa was measured and used as a measure of sludge formation prevention. The obtained results are shown in Tables 7-11. In addition, it shows that it is excellent in sludge production | generation suppression property, so that the numerical value of this operation time is large. “> 1000” in the table means that the differential pressure did not reach 100 kPa even after 1000 hours of operation.

It is explanatory drawing which shows the high temperature pump circulation test equipment used in the Example.

Claims (3)

Lubricating oil fractions obtained by subjecting crude oil to atmospheric distillation and / or vacuum distillation can be subjected to solvent degreasing, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing or clay treatment. It is at least one lubricating base oil selected from paraffinic mineral oil, normal paraffinic base oil and isoparaffinic base oil, which are refined by combining one of these refining treatments alone or in combination of two or more. ,% _{C A} of 2 or less,% _{C N} is 8 or _{more,% C} P /% C _N is 9.75 or more 35 or less, and the lubricating oil base oil is an iodine value of 2.5 or less,
An ashless antioxidant that does not contain sulfur as a constituent element;
Containing
The content of the ashless antioxidant, based on the total composition, Ri 0.3-5% by mass,
As the ashless antioxidant, it contains both a phenyl-α-naphthylamine compound and an alkylated diphenylamine compound, and
The lubricating oil composition , wherein a ratio of the alkylated diphenylamine compound to the total of the phenyl-α-naphthylamine compound and the alkylated diphenylamine compound is 0.1 to 0.9 in terms of mass ratio .   The lubricating oil composition according to claim 1, further comprising an alkyl group-substituted aromatic hydrocarbon compound. As the alkyl group-substituted aromatic hydrocarbon compound, a compound having one or two alkyl groups having 8 to 30 carbon atoms, which is at least one selected from alkylbenzene, alkylnaphthalene, alkylbiphenyl, and alkyldiphenylalkane The lubricating oil composition according to claim 2 , wherein:

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