JP2010090255A - Lubricant composition for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant composition for an internal combustion engine which is improved in all of viscosity-temperature characteristic, low-temperature viscosity characteristic and wear resistance in a high level and in a well-balanced state, and can effectively achieve fuel cost saving effect. <P>SOLUTION: The lubricant composition for the internal combustion engine comprises a lubricant base oil having a urea adduct value of ≤4 mass% and a viscosity index of ≥100 and a poly(meth)acrylate having a weight-average molecular weight of 200,000-400,000. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lubricating oil composition for an internal combustion engine.

  Conventionally, in the field of lubricating oils, by adding additives such as viscosity index improvers and pour point depressants to lubricating base oils such as highly refined mineral oils, the viscosity-temperature characteristics and low-temperature viscosity characteristics of lubricating oils are improved. (For example, refer to Patent Documents 1 to 7). Further, as a method for producing a high viscosity index base oil, a method of refining a lubricating base oil by hydrocracking / hydroisomerization is known for a raw material oil containing natural or synthetic normal paraffin (for example, (See Patent Documents 7 to 10).

The viscosity index of the lubricating base oil and the lubricating oil is generally a viscosity index, and the evaluation index of the low temperature viscosity characteristic is generally a pour point, a cloud point, a freezing point, and the like. In addition, a technique for evaluating low-temperature viscosity characteristics based on a lubricating base oil such as the content of normal paraffin or isoparaffin is also known.
JP-A-4-36391 Japanese Patent Laid-Open No. 4-68082 Japanese Patent Laid-Open No. 4-120193 JP 7-48421 A JP-A-7-62372 JP-A-6-145258 JP-A-3-100099 JP 2005-154760 A JP-T-2006-502298 JP-T-2002-503754

  In recent years, in the field of automobiles and the like, demands for fuel efficiency are increasing. However, even when a conventional lubricating base oil and a viscosity index improver are combined, it is difficult to say that practically sufficient fuel economy has been achieved.

  There is also an idea that if the viscosity index of the lubricating base oil is high, fuel consumption at high temperatures can be improved by reducing the viscosity. However, in actuality, lowering the viscosity lowers the wear resistance which is the basic performance of the lubricating oil, leading to a decrease in long-term reliability.

  The present invention has been made in view of such circumstances, and all of the viscosity-temperature characteristics, the low temperature viscosity characteristics, and the wear resistance are improved at a high level in a well-balanced manner, and the fuel efficiency is effectively achieved. An object of the present invention is to provide a lubricating oil composition for an internal combustion engine.

  In order to solve the above problems, the present invention provides a lubricating base oil having a urea adduct value of 4% by mass or less and a viscosity index of 100 or more (hereinafter referred to as “the lubricating base oil according to the present invention” in some cases). And a poly (meth) acrylate having a weight average molecular weight of 200,000 to 400,000 (hereinafter sometimes referred to as “poly (meth) acrylate according to the present invention”). A lubricating oil composition for an internal combustion engine is provided.

  Here, the “urea adduct value” in the present invention means a value measured by the following method. 100 g of weighed sample oil (lubricating base oil) is placed in a round bottom flask, 200 g of urea, 360 ml of toluene and 40 ml of methanol are added and stirred at room temperature for 6 hours. Thereby, white granular crystals are generated in the reaction solution. The reaction solution is filtered through a 1 micron filter to collect the produced white granular crystals, and the obtained crystals are washed 6 times with 50 ml of toluene. The recovered white crystals are put in a flask, 300 ml of pure water and 300 ml of toluene are added, and the mixture is stirred at 80 ° C. for 1 hour. The aqueous phase is separated and removed with a separatory funnel, and the toluene phase is washed three times with 300 ml of pure water. A desiccant (sodium sulfate) is added to the toluene phase for dehydration, and then toluene is distilled off. The ratio (mass percentage) of the hydrocarbon component (urea adduct) thus obtained to the sample oil is defined as the urea adduct value.

  In the measurement of the urea adduct value, as the urea adduct, normal paraffin remains in the isoparaffin component that adversely affects the low-temperature viscosity characteristics, the thermal conductivity deterioration component, or the lubricating base oil. In this case, the normal paraffin in the case can be collected accurately and reliably, so that it is excellent as a low temperature viscosity characteristic and thermal conductivity evaluation index of the lubricating base oil. The inventors of the present invention have analyzed by using GC and NMR that the main component of the urea adduct is a normal paraffin and an isoparaffin urea adduct having 6 or more carbon atoms from the end of the main chain to the branch position. Confirm that there is.

  Moreover, the viscosity index as used in the present invention and the kinematic viscosity at 40 ° C. or 100 ° C. described later mean a viscosity index measured according to JIS K 2283-1993 and a kinematic viscosity at 40 ° C. or 100 ° C., respectively. .

  Further, “poly (meth) acrylate” as used in the present invention is a general term for polyacrylate and polymethacrylate.

  The lubricating base oil according to the present invention is excellent in viscosity-temperature characteristics and low-temperature viscosity characteristics by satisfying the above conditions for the urea adduct value and the viscosity index, respectively, and has low viscosity resistance and stirring resistance, as well as heat and oxidation. Stability, friction characteristics and wear resistance are improved. Moreover, when an additive is mix | blended with the lubricating base oil of this invention, the function of the said additive can be expressed at a higher level. Therefore, according to the lubricating oil composition of the present invention, the above-mentioned excellent properties of the lubricating base oil according to the present invention and the addition effect of the poly (meth) acrylate according to the present invention are combined, and the viscosity -All of temperature characteristics, low-temperature viscosity characteristics and wear resistance can be improved in a well-balanced manner at a high level, and fuel efficiency can be effectively achieved.

  In addition, as described above, improvement of the isomerization rate from normal paraffin to isoparaffin has been studied in the conventional refining method of lubricating base oil by hydrocracking / hydroisomerization. According to the above study, it is difficult to sufficiently improve the low-temperature viscosity characteristics simply by reducing the residual amount of normal paraffin. That is, the isoparaffin produced by hydrocracking / hydroisomerization contains components that adversely affect the low-temperature viscosity characteristics, but this point is not fully recognized in conventional evaluation methods. Analytical techniques such as gas chromatography (GC) and NMR are applied to the analysis of normal paraffin and isoparaffin. In these analytical techniques, components that adversely affect the low-temperature viscosity characteristics are separated or specified from isoparaffin. This cannot be said to be practically effective because it requires complicated work and a lot of time.

  On the other hand, in the measurement of the urea adduct value in the present invention, as urea adduct, a component that adversely affects low-temperature viscosity characteristics among isoparaffins, and further when normal paraffin remains in the lubricating base oil Since the normal paraffin can be collected accurately and reliably, it is excellent as an evaluation index for the low temperature viscosity characteristics of the lubricating base oil.

  In the present invention, the lubricating base oil is hydrogenated so that the raw material oil containing normal paraffin has a urea adduct value of 4% by mass or less and a viscosity index of 100 or more. A lubricating base oil obtained by the process of cracking / hydroisomerization is preferred.

  Further, the raw material oil preferably contains 50% by mass or more of slack wax obtained by solvent dewaxing of the lubricating base oil.

  The lubricating oil composition for an internal combustion engine of the present invention has improved viscosity-temperature characteristics, low-temperature viscosity characteristics, and wear resistance at a high level in a well-balanced manner, and can effectively achieve fuel economy. It has the effect.

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

  The lubricating oil composition of the present invention contains a lubricating base oil having a urea adduct value of 4% by mass and a viscosity index of 100 or more.

  The urea adduct value of the lubricating base oil according to the present invention is required to be 4% by mass or less as described above from the viewpoint of improving the low temperature viscosity characteristics without impairing the viscosity-temperature characteristics, and preferably 3. 5 mass% or less, More preferably, it is 3 mass% or less, More preferably, it is 2.5 mass% or less. Further, the urea adduct value of the lubricating base oil may be 0% by mass.

  The viscosity index of the lubricating base oil according to the present invention needs to be 100 or more as described above from the viewpoint of viscosity-temperature characteristics, preferably 110 or more, more preferably 120 or more, still more preferably 130 or more. Especially preferably, it is 140 or more.

  When producing the lubricating base oil according to the present invention, a normal oil containing normal paraffin or a wax containing normal paraffin can be used. The raw material oil may be either mineral oil or synthetic oil, or may be a mixture of two or more of these. Further, the content of normal paraffin in the raw material oil is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, more preferably 90% by mass, based on the total amount of the raw material oil. Especially preferably, it is 95 mass% or more, Most preferably, it is 97 mass% or more.

  Moreover, it is preferable that the raw material oil used by this invention is a wax containing raw material which boils in the lubricating oil range prescribed | regulated to ASTM D86 or ASTM D2887. The wax content of the raw material oil is preferably 50% by mass or more and 100% by mass or less based on the total amount of the raw material oil. The wax content of the raw material can be measured by analytical techniques such as nuclear magnetic resonance spectroscopy (ASTM D5292), correlated ring analysis (ndM) method (ASTM D3238), solvent method (ASTM D3235) and the like.

  Examples of the wax-containing raw material include oils derived from solvent refining methods such as raffinate, partial solvent dewaxed oil, dewaxed oil, distillate, reduced pressure gas oil, coker gas oil, slack wax, foots oil, and fisher Examples include Tropsch wax, and among these, slack wax and Fischer-Tropsch wax are preferable.

  Slack waxes are typically derived from hydrocarbon feedstocks by solvent or propane dewaxing. Slack wax may contain residual oil, which can be removed by deoiling. Foots oil corresponds to deoiled slack wax.

  Fischer-Tropsch wax is produced by a so-called Fischer-Tropsch synthesis method.

  Furthermore, you may use a commercial item as raw material oil containing normal paraffin. Specific examples include Paraflint 80 (hydrogenated Fischer-Tropsch wax) and Shell MDS Waxy Raffinate (hydrogenated and partially isomerized middle distillate synthetic waxy raffinate). It is done.

  Moreover, the raw material oil derived from solvent extraction is obtained by sending a high-boiling petroleum fraction from atmospheric distillation to a vacuum distillation apparatus and solvent-extracting the distillation fraction from this apparatus. The residue from the vacuum distillation may be denitrified. In the solvent extraction method, aromatic components are dissolved in the extraction phase while leaving more paraffinic components in the raffinate phase. Naphthene is partitioned into the extraction phase and the raffinate phase. As the solvent for solvent extraction, phenol, furfural, N-methylpyrrolidone and the like are preferably used. By controlling the solvent / oil ratio, the extraction temperature, the method of contacting the distillate to be extracted with the solvent, etc., the degree of separation between the extraction phase and the raffinate phase can be controlled. Furthermore, a bottom fraction obtained from a fuel oil hydrocracking apparatus may be used as a raw material by using a fuel oil hydrocracking apparatus having higher hydrogenation resolution.

The raw material oil is subjected to hydrocracking / hydroisomerization so that the urea adduct value of the material to be treated is 4% by mass or less and the viscosity index is 100 or more. Such a lubricating base oil can be obtained. The hydrocracking / hydroisomerization step is not particularly limited as long as the urea adduct value and the viscosity index of the obtained workpiece satisfy the above conditions. The preferred hydrocracking / hydroisomerization step in the present invention is:
A first step of hydrotreating a raw oil containing normal paraffin using a hydrotreating catalyst;
A second step of hydrodewaxing the object to be treated obtained in the first step using a hydrodewaxing catalyst;
The to-be-processed object obtained by a 2nd process is equipped with the 3rd process of hydrotreating using a hydrotreating catalyst.

  In the conventional hydrocracking / hydroisomerization, a hydrotreating step is provided before the hydrodewaxing step for the purpose of desulfurization / denitrogenation for the prevention of poisoning of the hydrodewaxing catalyst. There is a thing. On the other hand, in the first step (hydrotreating step) in the present invention, a part of the normal paraffin in the feedstock (for example, about 10% by mass, preferably in the previous stage of the second step (hydrodewaxing step), preferably 1 to 10% by mass), and desulfurization / denitrogenation is possible in the first step, but the purpose is different from that of the conventional hydrotreatment. Providing such a first step is preferable for ensuring that the urea adduct value of the article to be processed (lubricant base oil) obtained after the third step is 4% by mass or less.

  Examples of the hydrogenation catalyst used in the first step include a catalyst containing a Group 6 metal, a Group 8-10 metal, and a mixture thereof. Preferred metals include nickel, tungsten, molybdenum, cobalt, and mixtures thereof. The hydrogenation catalyst can be used in a form in which these metals are supported on a refractory metal oxide support, and the metal is usually present as an oxide or sulfide on the support. When a metal mixture is used, the metal may be present as a bulk metal catalyst in which the amount of metal is 30% by mass or more based on the total amount of the catalyst. Examples of the metal oxide support include oxides such as silica, alumina, silica-alumina, and titania, and among these, alumina is preferable. Preferred alumina is γ-type or β-type porous alumina. The amount of metal supported is preferably in the range of 0.5 to 35% by mass based on the total amount of the catalyst. Also, when using a mixture of Group 9-10 metal and Group 6 metal, either Group 9 or Group 10 metal is present in an amount of 0.1-5% by weight, based on the total amount of catalyst, The Group 6 metal is preferably present in an amount of 5 to 30% by mass. Metal loading may be measured by atomic absorption spectroscopy, inductively coupled plasma emission spectroscopy, or other methods specified by ASTM for individual metals.

  The acidity of the metal oxide support can be controlled by adding additives, controlling the nature of the metal oxide support (eg, controlling the amount of silica incorporated into the silica-alumina support), and the like. Examples of additives include halogens, especially fluorine, phosphorus, boron, yttria, alkali metals, alkaline earth metals, rare earth oxides, and magnesia. Cocatalysts such as halogen generally increase the acidity of the metal oxide support, but weakly basic additives such as yttria or magnesia tend to weaken the acidity of such support.

Regarding the hydrotreatment conditions, the treatment temperature is preferably 150 to 450 ° C., more preferably 200 to 400 ° C., the hydrogen partial pressure is preferably 1400 to 20000 kPa, more preferably 2800 to 14000 kPa, and the liquid space velocity (LHSV) is preferably 0.1 to 10 ^-1, more preferably 0.1～5Hr ^-1, a hydrogen / oil ratio is preferably 50~1780m ³ / ^{m 3,} more preferably 89～890M ³ / M ³ . In addition, said conditions are an example and the hydrotreating conditions in the 1st process for the urea adduct value and viscosity index of the to-be-processed object obtained after a 3rd process satisfy | fill the said conditions respectively are a raw material, a catalyst, an apparatus, etc. It is preferable to select appropriately according to the difference.

  The object to be processed after the hydrogenation treatment in the first step may be used as it is in the second step, but the object to be processed is stripped or distilled to generate gas from the object to be processed (liquid product). It is preferable to provide a step of separating and removing the object between the first step and the second step. Thereby, the nitrogen content and sulfur content contained in the object to be treated can be reduced to a level without affecting the long-term use of the hydrodewaxing catalyst in the second step. The object of separation and removal by stripping or the like is mainly gaseous foreign matters such as hydrogen sulfide and ammonia, and stripping can be performed by ordinary means such as a flash drum and a fractionator.

  Moreover, when the conditions of the hydrogenation treatment in the first step are mild, there is a possibility that the remaining polycyclic aromatics may pass through depending on the raw materials used. It may be removed by purification.

  Further, the hydrodewaxing catalyst used in the second step may contain either crystalline or amorphous material. Examples of the crystalline material include molecular sieves having a 10- or 12-membered ring passage mainly composed of aluminosilicate (zeolite) or silicoaluminophosphate (SAPO). Specific examples of zeolite include ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-57, ferrierite, ITQ-13, MCM-68, MCM-71 and the like. Moreover, ECR-42 is mentioned as an example of an aluminophosphate. Examples of molecular sieves include zeolite beta and MCM-68. Among these, it is preferable to use 1 type, or 2 or more types selected from ZSM-48, ZSM-22, and ZSM-23, and ZSM-48 is particularly preferable. The molecular sieve is preferably in the hydrogen form. Although the reduction of the hydrodewaxing catalyst can occur in situ at the time of hydrodewaxing, a hydrodewaxing catalyst that has been subjected to a reduction treatment in advance may be subjected to hydrodewaxing.

  Examples of the amorphous material of the hydrodewaxing catalyst include alumina doped with a group 3 metal, fluorided alumina, silica-alumina, fluorided silica-alumina, silica-alumina, and the like.

  Preferred embodiments of the dewaxing catalyst include those equipped with bifunctional, ie, metal hydrogenation components that are at least one Group 6 metal, at least one Group 8-10 metal, or mixtures thereof. Preferred metals are group 9-10 noble metals such as Pt, Pd or mixtures thereof. The mounting amount of these metals is preferably 0.1 to 30% by mass based on the total amount of the catalyst. Examples of the catalyst preparation and the metal mounting method include an ion exchange method and an impregnation method using a decomposable metal salt.

  When molecular sieves are used, they may be combined with a binder material having heat resistance under hydrodewaxing conditions, or may be without a binder (self-bonding). As binder materials, silica, alumina, silica-alumina, combinations of two components of silica and other metal oxides such as titania, magnesia, tria, zirconia, silica-alumina-tria, silica-alumina-magnesia, etc. Inorganic oxides such as a combination of three components of oxides such as The amount of the molecular sieve in the hydrodewaxing catalyst is preferably 10 to 100% by mass, more preferably 35 to 100% by mass, based on the total amount of the catalyst. The hydrodewaxing catalyst is formed by a method such as spray drying or extrusion. The hydrodewaxing catalyst can be used in a sulfided or non-sulfided form, and a sulfided form is preferred.

Regarding hydrodewaxing conditions, the temperature is preferably 250-400 ° C., more preferably 275-350 ° C., and the hydrogen partial pressure is preferably 791-20786 kPa (100-3000 psig), more preferably 1480-17339 kPa (200- a 2500 psig), liquid hourly space velocity is preferably 0.1 to 10 ^-1, more preferably 0.1~5hr ^-1, a hydrogen / oil ratio is preferably 45~1780m ³ / ^{m 3} (250~10000scf / B), more preferably ^{89~890m 3 / m 3 (500~5000scf /} B). In addition, said conditions are an example and the hydrodewaxing conditions in the 2nd process for the urea adduct value and viscosity index of the to-be-processed object obtained after a 3rd process satisfy | fill the said conditions are a raw material, a catalyst, and an apparatus, respectively. It is preferable to select appropriately according to the difference.

  The object to be treated that has been hydrodewaxed in the second step is subjected to hydrorefining in the third step. Hydrorefining is a form of mild hydrotreating that aims to saturate olefins and residual aromatic compounds by hydrogenation in addition to removal of residual heteroatoms and hues. The hydrorefining in the third step can be carried out in cascade with the dewaxing step.

  The hydrorefining catalyst used in the third step is preferably a metal oxide carrier on which a Group 6 metal, a Group 8-10 metal or a mixture thereof is supported. Preferred metals include noble metals, especially platinum, palladium and mixtures thereof. If a mixture of metals is used, it may be present as a bulk metal catalyst where the amount of metal is 30% by weight or more based on the catalyst. The metal content of the catalyst is preferably 20% by mass or less for non-noble metals and 1% by mass or less for noble metals. The metal oxide support may be either amorphous or crystalline oxide. Specific examples include low acid oxides such as silica, alumina, silica-alumina or titania, and alumina is preferred. From the viewpoint of saturation of the aromatic compound, it is preferable to use a hydrorefining catalyst in which a metal having a relatively strong hydrogenation function is supported on a porous support.

  Preferred hydrorefining catalysts include mesoporous materials belonging to the M41S class or family of catalysts. M41S series catalysts are mesoporous materials with high silica content, and specifically include MCM-41, MCM-48 and MCM-50. Such a hydrorefining catalyst has a pore diameter of 15 to 100 mm, and MCM-41 is particularly preferable. MCM-41 is an inorganic porous non-layered phase having a hexagonal arrangement of uniformly sized pores. The physical structure of MCM-41 is like a bundle of straws where the opening of the straw (cell diameter of the pores) is in the range of 15-100 angstroms. MCM-48 has cubic symmetry, and MCM-50 has a layered structure. MCM-41 can be manufactured with pore openings of different sizes in the mesoporous range. The mesoporous material may have a metal hydrogenation component that is at least one of a Group 8, 9 or 10 metal, and the metal hydrogenation component is preferably a noble metal, particularly a Group 10 noble metal, Pt , Pd or mixtures thereof are most preferred.

Regarding the hydrorefining conditions, the temperature is preferably 150-350 ° C, more preferably 180-250 ° C, the total pressure is preferably 2859-20786 kPa (about 400-3000 psig), and the liquid space velocity is preferably 0. 0.1 to 5 hr ⁻¹ , more preferably 0.5 to ³ hr ⁻¹ , and the hydrogen / oil ratio is preferably 44.5 to 1780 m ³ / m ³ (250 to 10,000 scf / B). In addition, said conditions are an example and the hydrogenation production | generation conditions in the 3rd process for the urea adduct value and viscosity index of the to-be-processed object obtained after a 3rd process satisfy | fill the said conditions respectively are the difference of a raw material or a processing apparatus. It is preferable to select appropriately according to.

  Moreover, about the to-be-processed object obtained after a 3rd process, you may separate and remove a predetermined component by distillation etc. as needed.

  In the lubricating base oil according to the present invention obtained by the above production method, the other properties are not particularly limited as long as the urea adduct value and the viscosity index satisfy the above conditions, respectively, but the lubricating base oil according to the present invention is It is preferable that the following conditions are further satisfied.

  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 oil base oil. Moreover, the ratio of the cyclic | annular saturated part to the said saturated part becomes like this. Preferably it is 0.1-50 mass%, More preferably, it is 0.5-40 mass%, More preferably, it is 1-30 mass%, Most preferably, it is 5-20. % By mass. Viscosity-temperature characteristics and thermal / oxidative stability can be achieved by satisfying the above conditions for the content of the saturated component and the ratio of the cyclic saturated component in the saturated component, respectively. When the additive is blended, the function of the additive can be expressed at a higher level while the additive is sufficiently stably dissolved and held in the lubricating base oil. Furthermore, when the content of the saturated component and the ratio of the cyclic saturated component in the saturated component satisfy the above conditions, the friction characteristics of the lubricating base oil itself can be improved, and as a result, the friction reducing effect is improved. As a result, energy saving can be improved.

  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. Further, 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 becomes insufficient, and the lubricating base Since the effective amount of the additive dissolved and retained in the oil is reduced, the function of the additive tends to be unable to be obtained effectively. Furthermore, when the ratio of the cyclic saturated component in the saturated component exceeds 50% by mass, the effectiveness of the additive tends to decrease when the additive is blended with the lubricating base oil.

  In the present invention, the ratio of the cyclic saturated component in the saturated component being 0.1 to 50% by mass is equivalent to the non-cyclic saturated component in the saturated component being 99.9 to 50% by mass. Here, the non-cyclic saturated component includes both normal paraffin and isoparaffin. The ratio of normal paraffin and isoparaffin in the lubricating base oil according to the present invention is not particularly limited as long as the urea adduct value satisfies the above conditions, but the ratio of isoparaffin is preferably 50 to 99 based on the total amount of the lubricating base oil. 9.9% by mass, more preferably 60 to 99.9% by mass, still more preferably 70 to 99% by mass, and particularly preferably 80 to 99.9% by mass. When the ratio of isoparaffin in the lubricating base oil satisfies the above conditions, the viscosity-temperature characteristics and thermal / oxidative stability can be further improved, and when the additive is added to the lubricating base oil Therefore, the function of the additive can be expressed at a higher level while the additive is sufficiently stably dissolved and held.

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

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

In addition, the ratio of normal paraffin in the lubricating base oil referred to in the present invention is a gas chromatographic analysis of the saturated component separated and fractionated by the method described in ASTM D 2007-93 under the following conditions. This means a value obtained by converting the measured value when the ratio of normal paraffin in the saturated content is identified and quantified, based on the total amount of the lubricating base oil. In the identification and quantification, a normal paraffin mixed sample having 5 to 50 carbon atoms is used as a standard sample, and the normal paraffin occupying the saturated component is the total peak area value of the chromatogram (the peak derived from the diluent). Is obtained as a ratio of the sum of peak area values corresponding to each normal paraffin.
(Gas chromatography conditions)
Column: non-polar liquid phase column (length 25 m, 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)
Further, the ratio of isoparaffin in the lubricating base oil means a value obtained by converting the difference between the non-cyclic saturated component in the saturated component and the normal paraffin component in the saturated component, based on the total amount of the lubricant base oil. .

  In the method of separating saturated components, or in analyzing the composition 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.

  In the lubricating base oil according to the present invention, when the bottom fraction obtained from the fuel oil hydrocracking apparatus is used as a raw material, the content of the saturated component is 90% by mass or more and occupies the saturated component. The proportion of cyclic saturated component is 30 to 50% by mass, the proportion of non-cyclic saturated component in the saturated component is 50 to 70% by mass, the proportion of isoparaffin in the lubricating base oil is 40 to 70% by mass, and the viscosity index is Although a base oil of 100 to 135, preferably 120 to 130 is obtained, the urea adduct value satisfies the above conditions, the effect of the present invention, the improvement of low temperature viscosity characteristics and the wear prevention property and low friction property when soot is mixed. Can be achieved, and in particular, it is possible to obtain an effect that a significant improvement in low-temperature viscosity characteristics can be realized. In the lubricating base oil according to the present invention, when a slack wax or Fischer-Tropsch wax, which is a raw material having a high wax content (for example, a normal paraffin content of 50% by mass or more) is used as a raw material, Of 90% by mass or more, the proportion of cyclic saturated component in the saturated component is 0.1 to 40% by mass, the proportion of non-cyclic saturated component in the saturated component is 60 to 99.9% by mass, lubrication A base oil having a ratio of isoparaffin in the oil base oil of 60 to 99.9% by mass and a viscosity index of 100 to 170, preferably 135 to 160 is obtained. Oil composition, which has both the improvement of low-temperature viscosity characteristics and anti-wear and low-friction properties when mixed with soot, and has particularly excellent characteristics in terms of high viscosity index and low temperature viscosity characteristics. It is possible to obtain.

  The aromatic content in the lubricating base oil according to the present invention is preferably 5% by mass or less, more preferably 0.05 to 3% by mass, and still more preferably 0.1 to 3% by mass, based on the total amount of the lubricating base oil. 1% by mass, particularly preferably 0.1 to 0.5% by mass. If the aromatic content exceeds the above upper limit, the viscosity-temperature characteristics, thermal / oxidative stability, friction characteristics, volatilization prevention characteristics and low-temperature viscosity characteristics tend to decrease. When an additive is blended with the additive, the effectiveness of the additive tends to decrease. Further, the lubricating base oil according to the present invention may not contain an aromatic component, but the solubility of the additive is further improved by setting the aromatic content to 0.05% by mass or more. Can be increased.

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

Further, the% C _p of the lubricating base oil according to the present invention is preferably 80 or more, more preferably 82 to 99, still more preferably 85 to 98, and particularly preferably 90 to 97. If the% C _p of the lubricating base oil is less than 80, the viscosity-temperature characteristics, thermal / oxidative stability, and friction characteristics tend to be reduced, and when the additive is added to the lubricating base oil The effectiveness of the additive tends to decrease. Further, when the% C _p value of the lubricating base oil exceeds 99, the additive solubility will tend to be lower.

Moreover,% _{C N} of the lubricating base oil according to the present invention is preferably 20 or less, more preferably 15 or less, more preferably 1 to 12, particularly preferably 3 to 10. If the% C _N value of the lubricating base oil exceeds 20, the viscosity - temperature characteristic, heat and oxidation stability and frictional properties will tend to be reduced. Moreover, when% _CN is less than 1, the solubility of the additive tends to decrease.

Moreover,% _{C A} of the lubricating base oil according to the present invention is preferably 0.7 or less, more preferably 0.6 or less, more preferably 0.1 to 0.5. When% C _A of the lubricating base oil exceeds 0.7, the viscosity - temperature characteristic, heat and oxidation stability and frictional properties will tend to be reduced. Moreover,% C _A of the lubricating base oil according to the present invention may be 0% by 0.1 or more C _A, it is possible to further increase the solubility of additives.

Furthermore, the ratio of the lubricating base% in oil _{C P} and% _{C N} of the present _invention,% C is preferably P /% _{C N} is 7 or more, more preferably 7.5 or more, More preferably, it is 8 or more. When% C _P /% _CN is less than 7, viscosity-temperature characteristics, thermal / oxidative stability and friction characteristics tend to be reduced, and further when an additive is blended in the lubricating base oil. The effectiveness of the additive tends to decrease. _{Moreover,% C} P /% C _N is preferably 200 or less, more preferably 100 or less, more preferably 50 or less, particularly preferably 25 or less. By setting% C _P /% _CN to 200 or less, the solubility of the additive can be further increased.

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.

  The iodine value of the lubricating base oil of the present invention is preferably 0.5 or less, more preferably 0.3 or less, still more preferably 0.15 or less, and less than 0.01. However, it is preferably 0.001 or more, more preferably 0.05 or more, from the viewpoint of small effects that are commensurate with it and economic efficiency. By setting the iodine value of the lubricating base oil to 0.5 or less, the thermal and oxidation stability can be dramatically improved. In addition, the iodine value as used in the field of this invention means the iodine value measured by the indicator titration method of JIS K0070 "the acid value of a chemical product, the saponification value, the iodine value, the hydroxyl value, and the unsaponification value."

  Further, the content of sulfur in the lubricating base oil according to the present invention depends on the content of sulfur in the raw material. For example, when a raw material that does not substantially contain sulfur such as a synthetic wax component obtained by a Fischer-Tropsch reaction or the like is used, a lubricating base oil that does not substantially contain sulfur can be obtained. In addition, when using raw materials containing sulfur such as slack wax obtained in the refining process of the lubricating base oil and microwax obtained in the refining process, the sulfur content in the obtained lubricating base oil is usually 100 mass ppm. There is a possibility of this. In the lubricating base oil according to the present invention, the content of sulfur is preferably 10 ppm by mass or less, and is preferably 5 ppm by mass or less, from the viewpoint of further improving thermal and oxidation stability and reducing sulfur content. More preferred is 3 ppm by mass or less.

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

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

The kinematic viscosity of the lubricating base oil according to the present invention is preferably 1.5 to ²⁰ mm ² / s, more preferably 2.0 to 11 mm ² / s at 100 ° C. 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-mentioned lubricating base oils (I) and (IV) have a viscosity-temperature characteristic and low temperature compared with conventional lubricating base oils having the same viscosity grade by satisfying the above conditions for the urea adduct value and the viscosity index, respectively. Viscosity characteristics can be achieved at a high level, in particular, low temperature viscosity characteristics are excellent, and viscosity resistance and stirring resistance can be significantly 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.

  The lubricating base oils (II) and (V) have a viscosity-temperature characteristic compared to a conventional lubricating base oil having the same viscosity grade by satisfying the above conditions for the urea adduct value and the viscosity index, respectively. And low-temperature viscosity characteristics can be achieved at a high level. In particular, the low-temperature viscosity characteristics are excellent, and further, volatilization prevention and lubricity are excellent. For example, in the lubricating base oils (II) and (V), the CCS viscosity at −35 ° C. can be 3000 mPa · s or less, preferably 2000 mPa · s or less. Further, by blending a pour point depressant, the MRV viscosity at −40 ° C. can be 10000 mPa · s or less, preferably 8000 mPa · s or less.

  In addition, the lubricating base oils (III) and (VI) have viscosity-temperature characteristics compared to conventional lubricating base oils having the same viscosity grade by satisfying the above conditions for the urea adduct value and the viscosity index, respectively. And low-temperature viscosity characteristics can be achieved at a high level. In particular, the low-temperature viscosity characteristics are excellent, and further, volatilization prevention, thermal / oxidative stability, and lubricity are excellent.

  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 of the lubricating base oils (II) and (V) at −35 ° C. is preferably 3000 mPa · s or less, more preferably 2400 mPa · s or less, still more preferably 2000 mPa · s or less, and further preferably 1800 mPa. · S or less, more preferably 1600 mPa · s or less, particularly preferably 1500 mPa · s or less. 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. 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.

  In addition, the BF viscosity at −40 ° C. of the lubricating base oil according to the present invention depends on the viscosity grade of the lubricating base oil, for example, at −40 ° C. of the lubricating base oils (I) and (IV). The BF viscosity is preferably 10,000 mPa · s or less, more preferably 8000 mPa · s, and still more preferably 6000 mPa · s or less. Moreover, the BF viscosity at −40 ° C. of the lubricating base oils (II) and (V) is preferably 1500,000 mPa · s or less, more preferably 1000000 mPa · s or less. When the BF viscosity at −40 ° C. exceeds the upper limit, the low-temperature fluidity of the entire lubricating oil using the lubricating base oil tends to decrease.

Further, the density (ρ ₁₅ ) (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 is not more than the value of ρ represented by the following formula (1). That is, it is preferable that ρ ₁₅ ≦ ρ.
ρ = 0.0025 × kv100 + 0.816 (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 = 4.3 × kv100 + 100 (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. The AP of the lubricating base oils (II) and (V) is preferably 113 ° C. or higher, more preferably 119 ° C. or higher. The AP of the lubricating base oils (III) and (VI) is preferably 125 ° C. or higher, 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 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. Lubricating 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 the range. Obtainable.

  For example, regarding the distillation properties of the lubricating base oils (I) and (IV), the initial boiling point (IBP) is preferably 260 to 340 ° C, more preferably 270 to 330 ° C, and still more preferably 280 to 320 ° C. It is. Moreover, 10% distillation temperature (T10) becomes like this. Preferably it is 310-390 degreeC, More preferably, it is 320-380 degreeC, More preferably, it is 330-370 degreeC. Moreover, 50% distillation point (T50) becomes like this. Preferably it is 340-440 degreeC, More preferably, it is 360-430 degreeC, More preferably, it is 370-420 degreeC. Moreover, 90% distillation point (T90) becomes like this. Preferably it is 405-465 degreeC, More preferably, it is 415-455 degreeC, More preferably, it is 425-445 degreeC. Moreover, an end point (FBP) becomes like this. Preferably it is 430-490 degreeC, More preferably, it is 440-480 degreeC, More preferably, it is 450-490 degreeC. Moreover, T90-T10 becomes like this. Preferably it is 60-140 degreeC, More preferably, it is 70-130 degreeC, More preferably, it is 80-120 degreeC. Moreover, FBP-IBP becomes like this. Preferably it is 140-200 degreeC, More preferably, it is 150-190 degreeC, More preferably, it is 160-180 degreeC. Further, T10-IBP is preferably 40 to 100 ° C, more preferably 50 to 90 ° C, and further preferably 60 to 80 ° C. Moreover, FBP-T90 becomes like this. Preferably it is 5-60 degreeC, More preferably, it is 10-55 degreeC, More preferably, it is 15-50 degreeC.

  Further, regarding the distillation properties of the lubricating base oils (II) and (V), the initial boiling point (IBP) is preferably 310 to 400 ° C, more preferably 320 to 390 ° C, still more preferably 330 to 380 ° C. It is. Moreover, 10% distillation temperature (T10) becomes like this. Preferably it is 350-430 degreeC, More preferably, it is 360-420 degreeC, More preferably, it is 370-410 degreeC. The 50% distillation point (T50) is preferably 390 to 470 ° C, more preferably 400 to 460 ° C, still more preferably 410 to 450 ° C. Moreover, 90% distillation point (T90) becomes like this. Preferably it is 420-490 degreeC, More preferably, it is 430-480 degreeC, More preferably, it is 440-470 degreeC. Moreover, an end point (FBP) becomes like this. Preferably it is 450-530 degreeC, More preferably, it is 460-520 degreeC, More preferably, it is 470-510 degreeC. Moreover, T90-T10 becomes like this. Preferably it is 40-100 degreeC, More preferably, it is 45-90 degreeC, More preferably, it is 50-80 degreeC. Moreover, FBP-IBP becomes like this. Preferably it is 80-170 degreeC, More preferably, it is 100-160 degreeC, More preferably, it is 120-150 degreeC. T10-IBP is preferably 5 to 60 ° C, more preferably 10 to 55 ° C, and still more preferably 15 to 50 ° C. Moreover, FBP-T90 becomes like this. Preferably it is 5-60 degreeC, More preferably, it is 10-55 degreeC, More preferably, it is 15-50 degreeC.

  The initial boiling point (IBP) of the lubricating base oils (III) and (VI) is preferably 440 to 480 ° C, more preferably 430 to 470 ° C, and still more preferably 420 to 460 ° C. It is. Moreover, 10% distillation temperature (T10) becomes like this. Preferably it is 450-510 degreeC, More preferably, it is 460-500 degreeC, More preferably, it is 460-480 degreeC. The 50% distillation point (T50) is preferably 470 to 540 ° C, more preferably 480 to 530 ° C, still more preferably 490 to 520 ° C. Moreover, 90% distillation point (T90) becomes like this. Preferably it is 470-560 degreeC, More preferably, it is 480-550 degreeC, More preferably, it is 490-540 degreeC. Moreover, an end point (FBP) becomes like this. Preferably it is 505-565 degreeC, More preferably, it is 515-555 degreeC, More preferably, it is 525-565 degreeC. Moreover, T90-T10 becomes like this. Preferably it is 35-80 degreeC, More preferably, it is 45-70 degreeC, More preferably, it is 55-80 degreeC. Moreover, FBP-IBP becomes like this. Preferably it is 50-130 degreeC, More preferably, it is 60-120 degreeC, More preferably, it is 70-110 degreeC. Further, T10-IBP is preferably 5 to 65 ° C, more preferably 10 to 55 ° C, and still more preferably 10 to 45 ° C. Moreover, FBP-T90 becomes like this. Preferably it is 5-60 degreeC, More preferably, it is 5-50 degreeC, More preferably, it is 5-40 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 lubricating base oil according to the present invention may be composed only of the lubricating base oil component according to the present invention, but a mineral base oil or a synthetic base other than the lubricating base oil component according to the present invention. You may further contain the oil or the arbitrary mixtures of 2 or more types of lubricating oil chosen from these. However, when the lubricating base oil component according to the present invention and other lubricating base oil components are used in combination, the ratio of the other lubricating base oil components is based on the total amount of the lubricating base oil according to the present invention. It is preferable to set it to 90 mass% or less.

  That is, when a mixed base oil of the lubricating base oil according to the present invention and another lubricating base oil is used, the content of the lubricating base oil according to the present invention is preferably based on the total amount of the mixed base oil. It is 10-100 mass%, More preferably, it is 30 mass% or more, More preferably, it is 50 mass% or more, More preferably, it is 70 mass% or more, Most preferably, it is 80 mass% or more. When the said content rate is less than 10 mass%, there exists a possibility that the required low temperature viscosity and fuel-saving performance may not be obtained.

Although it does not restrict | limit especially as another lubricating base oil component used together with the lubricating base oil component which concerns on this invention, As a mineral oil type | system | group base oil, the solvent whose dynamic viscosity in 100 degreeC is 1-100 mm < ² > / s, for example Refined mineral oil, hydrocracked mineral oil, hydrorefined mineral oil, solvent dewaxing base oil and the like.

  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 poly (meth) acrylate having a weight average molecular weight of 200,000 to 400,000.

The weight average molecular weight (M _w ) of the poly (meth) acrylate according to the present invention needs to be 200,000 to 400,000, preferably 225,000 to 375,000, and more preferably 275,000. ~ 325,000. When the weight average molecular weight is less than 200,000, the effect of improving the viscosity index is small and not only the fuel saving property and the low temperature viscosity characteristic are inferior, but also the cost may increase, and the weight average molecular weight exceeds 400,000. May deteriorate the shear stability, solubility in base oil, and storage stability.

  The PSSI (Permanent Cystability Index) of the poly (meth) acrylate according to the present invention is preferably 80 or less, more preferably 5 to 60, still more preferably 20 to 55, still more preferably 30 to 50, particularly preferably 35 to 35. 45. If PSSI exceeds 80, shear stability may be deteriorated. Further, when PSSI is less than 5, the effect of improving the viscosity index is small, which is not only inferior in fuel economy and low-temperature viscosity characteristics, but also in cost.

The ratio of the weight average molecular weight to number average molecular weight of the poly (meth) acrylates according to the present invention _(M W / _{M n)} is preferably from 0.5 to 5.0, more preferably 1.0 to 3 0.5, more preferably 1.5 to 3, particularly preferably 1.7 to 2.5. When the ratio of the weight average molecular weight to the number average molecular weight is 0.5 or less or 5.0 or more, not only the solubility in the base oil and the storage stability are deteriorated, but also the viscosity-temperature characteristics are deteriorated, and the fuel economy is improved. May get worse. The weight average molecular weight and the number average molecular weight used here are two columns of Tosoh's GMHHR-M (7.8 mm ID × 30 cm) in series on a Waters 150-C ALC / GPC apparatus, As tetrahydrofuran, temperature 23 ° C., flow rate 1 mL / min, sample concentration 1 mass%, sample injection amount 75 μL, weight average molecular weight and number average molecular weight in terms of polystyrene measured with a detector differential refractometer (RI). .

The ratio of the weight average molecular weight of the poly (meth) acrylate and PSSI of the present invention _(M W / PSSI) is preferably at 2.5 × 10 ⁴ or less, more preferably less than 1 × 10 ^4, further Preferably it is 0.9 × 10 ⁴ or less, preferably 0.5 × 10 ⁴ or more. In particular, by making M _W / PSSI less than 1 × 10 ⁴ , seizure resistance and wear resistance can be further improved. It is to be noted that the PSSI referred to herein, conform to ASTM D 6022-01 (Standard Practice for Calculation of Permanent Shear Stability Index), ASTM D 6278-02 (Test Metohd for Shear Stability of Polymer Containing Fluids Using a European Diesel Injector Apparatus ) Means the permanent shear stability index of the polymer, calculated based on the data measured by.

  The poly (meth) acrylate according to the present invention preferably contains one or more (meth) acrylate structural units represented by the following general formula (1) as structural units. Such poly (meth) acrylate may be either non-dispersed or dispersed, but is more preferably dispersed.

[In formula (1), R ¹ represents hydrogen or a methyl group, R ² represents a linear or branched hydrocarbon group having 1 to 50 carbon atoms. ]
R ² in the structural unit represented by the formula (1) is a linear or branched hydrocarbon group having 1 to 50 carbon atoms as described above, preferably a linear or branched group having 1 to 30 carbon atoms. It is a branched hydrocarbon, more preferably a linear or branched hydrocarbon having 1 to 20 carbon atoms, and more preferably a linear hydrocarbon group having 1 to 15 carbon atoms.

  As long as the poly (meth) acrylate according to the present invention has the (meth) acrylate structural unit represented by the general formula (1), any (meth) acrylate monomer or any olefin may be copolymerized. Obtainable.

  Although the monomer polymerized in order to obtain the poly (meth) acrylate according to the present invention is arbitrary, for example, a monomer represented by the following general formula (2) (hereinafter referred to as “monomer (M-1)”) is preferable. It is. The (co) polymer of the monomer (M-1) is a so-called non-dispersed poly (meth) acrylate.

[In the general formula (2), R ¹ represents a hydrogen atom or a methyl group, and R ² represents a linear or branched hydrocarbon group having 1 to 50 carbon atoms. ]
Preferred examples of the monomer (M-1) include alkyl (meth) acrylates having a linear or branched alkyl group having 1 to 30 carbon atoms, preferably a linear alkyl group having 1 to 20 carbon atoms. , Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate , Nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, Examples include butadecyl (meth) acrylate, octadecyl (meth) acrylate, etc. (these alkyl groups are preferably linear alkyl groups), and particularly methyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate. It is preferable that it is a monomer containing an acrylate, and it is a monomer having methyl methacrylate, n-dodecyl methacrylate, n-tridecyl methacrylate, n-tetradecyl methacrylate, n-pentadecyl methacrylate as a main constituent unit. Is particularly preferred.

  Moreover, as another monomer polymerized in order to obtain the poly (meth) acrylate which concerns on this invention, the monomer (henceforth "monomer (M-2)") represented by the following general formula (3), and One or more selected from monomers represented by the following general formula (4) (hereinafter referred to as “monomer (M-3)”) are preferable. The (co) polymer of the monomer containing the monomer (M-3) and / or (M-4) is a so-called dispersed poly (meth) acrylate. In addition, it is preferable that the said dispersion | distribution type poly (meth) acrylate contains the monomer (M-1) as a structural monomer.

[In the above general formula (3), R ⁵ represents a hydrogen atom or a methyl group, R ⁶ represents an alkylene group having 1 to 18 carbon atoms, E ¹ represents ¹ to 2 nitrogen atoms and 0 to 0 oxygen atoms. 2 represents an amine residue or heterocyclic residue, and a represents 0 or 1. ]
Specific examples of the alkylene group having 1 to 18 carbon atoms represented by R ⁶ include an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, Examples include an undecylene group, a dodecylene group, a tridecylene group, a tetradecylene group, a pentadecylene group, a hexadecylene group, a heptadecylene group, and an octadecylene group (these alkylene groups may be linear or branched).

Specific examples of the group represented by E ¹ include a dimethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, an anilino group, a toluidino group, a xylidino group, an acetylamino group, a benzoylamino group, Examples include morpholino group, pyrrolyl group, pyrrolino group, pyridyl group, methylpyridyl group, pyrrolidinyl group, piperidinyl group, quinonyl group, pyrrolidonyl group, pyrrolidono group, imidazolino group, and pyrazino group.

[In the general formula (4), R ⁷ represents a hydrogen atom or a methyl group, and E ² represents an amine residue or a heterocyclic residue containing 1 to 2 nitrogen atoms and 0 to 2 oxygen atoms. . ]
Specific examples of the group represented by E ² include a dimethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, an anilino group, a toluidino group, a xylidino group, an acetylamino group, a benzoylamino group, and a morpholino group. Pyrrolyl group, pyrrolino group, pyridyl group, methylpyridyl group, pyrrolidinyl group, piperidinyl group, quinonyl group, pyrrolidonyl group, pyrrolidono group, imidazolino group, pyrazino group and the like.

  As preferable examples of the monomers (M-2) and (M-3), specifically, dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-methyl-5-vinylpyridine, Examples thereof include morpholinomethyl methacrylate, morpholinoethyl methacrylate, N-vinylpyrrolidone, and mixtures thereof.

  The method for producing the poly (meth) acrylate according to the present invention is arbitrary. For example, in the presence of a polymerization initiator such as benzoyl peroxide, a mixture of the monomers (M-1) to (M-3) is radical solution. It can be easily obtained by polymerization.

  The poly (meth) acrylate according to the present invention includes a monomer having methyl methacrylate, n-dodecyl methacrylate, n-tridecyl methacrylate, n-tetradecyl methacrylate, and n-pentadecyl methacrylate as main structural units; Dispersed polymethacrylate obtained by copolymerizing one or more selected from the monomers (M-2) and (M-3) is most preferable.

  The content of the poly (meth) acrylate according to the present invention is preferably 0.1 to 50% by mass, more preferably 0.5 to 40% by mass, still more preferably 1 to 30% by mass, based on the total amount of the composition. Especially preferably, it is 5-20 mass%. When the content of poly (meth) acrylate is less than 0.1% by mass, the effect of improving the viscosity index and the effect of reducing the product viscosity are diminished, and thus there is a possibility that the fuel economy cannot be improved. Also, if it exceeds 50% by mass, the product cost will increase significantly and the viscosity of the base oil will need to be reduced. There is a concern that defects such as burn-in, seizure and fatigue failure may be the cause.

  In addition to the poly (meth) acrylate according to the present invention described above, the lubricating oil composition of the present invention may be an ordinary general non-dispersed or dispersed poly (meth) acrylate, non-dispersed or dispersed ethylene- An α-olefin copolymer or a hydride thereof, polyisobutylene or a hydride thereof, a styrene-diene hydrogenated copolymer, a styrene-maleic anhydride ester copolymer, a polyalkylstyrene, or the like may be further contained.

  In order to further improve the performance, the lubricating oil composition of the present invention may contain any additive generally used in lubricating oils depending on the purpose. Examples of such additives include friction modifiers, metal detergents, ashless dispersants, antioxidants, antiwear agents (or extreme pressure agents), corrosion inhibitors, rust inhibitors, pour point depressants, Examples include additives such as demulsifiers, metal deactivators, and antifoaming agents.

  For example, the lubricating oil composition of the present invention may further contain a friction modifier selected from organic molybdenum compounds and ashless friction modifiers in order to improve fuel economy performance.

  Examples of the organic molybdenum compound used in the present invention include organic molybdenum compounds containing sulfur such as molybdenum dithiophosphate and molybdenum dithiocarbamate.

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

  Other organic molybdenum compounds containing sulfur include molybdenum compounds (for example, molybdenum oxide such as molybdenum dioxide and molybdenum trioxide, orthomolybdic acid, paramolybdic acid, molybdic acid such as (poly) sulfurized molybdic acid, Molybdate such as metal salts of molybdic acid, ammonium salts, molybdenum disulfide, molybdenum trisulfide, molybdenum pentasulfide, molybdenum sulfide such as polysulfide molybdenum, metal sulfide or amine salt of molybdenum sulfide, sulfurized molybdenum acid, chloride Molybdenum halides such as molybdenum) and sulfur-containing organic compounds (eg, alkyl (thio) xanthates, thiadiazoles, mercaptothiadiazoles, thiocarbonates, tetrahydrocarbyl thiuram disulfides, bis (di (thio) hydrocarbons) Bildithiophosphonate) disulfide, organic (poly) sulfide, sulfurized ester, etc.) or other organic compound complexes, etc., or sulfur-containing molybdenum compounds such as molybdenum sulfide, sulfurized molybdic acid, etc. and alkenyl succinimide complexes, etc. Can be mentioned.

  As the organic molybdenum compound, an organic molybdenum compound containing no sulfur as a constituent element can be used.

  Specific examples of organic molybdenum compounds that do not contain sulfur as a constituent element include molybdenum-amine complexes, molybdenum-succinimide complexes, molybdenum salts of organic acids, and molybdenum salts of alcohols. Complexes, molybdenum salts of organic acids and molybdenum salts of alcohols are preferred.

  In the lubricating oil composition of the present invention, when an organic molybdenum compound is used, its content is not particularly limited, but is preferably 0.001% by mass or more, more preferably 0, in terms of molybdenum element, based on the total amount of the composition. 0.005% by mass or more, more preferably 0.01% by mass or more, preferably 0.2% by mass or less, more preferably 0.1% by mass or less, still more preferably 0.05% by mass or less, particularly Preferably it is 0.03 mass% or less. When the content is less than 0.001% by mass, the thermal and oxidation stability of the lubricating oil composition becomes insufficient, and in particular, it tends to be impossible to maintain excellent cleanliness over a long period of time. On the other hand, when the content exceeds 0.2% by mass, an effect commensurate with the content cannot be obtained, and the storage stability of the lubricating oil composition tends to decrease.

  As the ashless friction modifier used in the present invention, any compound usually used as a friction modifier for lubricating oils can be used, for example, an alkyl group or alkenyl group having 6 to 30 carbon atoms, particularly the number of carbon atoms. Amine compound, ester compound, amide compound, imide compound, ether compound, urea compound, hydrazide compound, fatty acid ester, fatty acid amide, fatty acid having at least one linear alkyl group or straight chain alkenyl group of 6 to 30 in the molecule Ashless friction modifiers such as aliphatic alcohols and aliphatic ethers. Further, one or more compounds selected from the group consisting of nitrogen-containing compounds represented by the following general formulas (5) and (6) and acid-modified derivatives thereof, and various examples exemplified in International Publication No. 2005/037967 pamphlet. Ashless friction modifiers may be mentioned.

In the general formula (5), R ⁸ has a hydrocarbon group having 1 to 30 carbon atoms or a hydrocarbon group having 1 to 30 carbon atoms, preferably a hydrocarbon group having 10 to 30 carbon atoms or a functionality. A hydrocarbon group having 10 to 30 carbon atoms, more preferably an alkyl group having 12 to 20 carbon atoms, an alkenyl group or a functional hydrocarbon group, particularly preferably an alkenyl group having 12 to 20 carbon atoms, R ⁹ and R ¹⁰ each independently has a hydrocarbon group having 1 to 30 carbon atoms, a hydrocarbon group having 1 to 30 carbon atoms or hydrogen having functionality, preferably a hydrocarbon group having 1 to 10 carbon atoms, or functionality. A hydrocarbon group or hydrogen having 1 to 10 carbon atoms, more preferably a hydrocarbon group or hydrogen having 1 to 4 carbon atoms, more preferably hydrogen, and X represents oxygen or sulfur, preferably oxygen.

In the general formula (6), R ¹¹ is a hydrocarbon group having 1 to 30 carbon atoms or a hydrocarbon group having 1 to 30 carbon atoms having functionality, preferably a hydrocarbon group or functionality having 10 to 30 carbon atoms. A hydrocarbon group having 10 to 30 carbon atoms, more preferably an alkyl group having 12 to 20 carbon atoms, an alkenyl group or a hydrocarbon group having functionality, particularly preferably an alkenyl group having 12 to 20 carbon atoms, and R ¹² _, R ¹³ and R ¹⁴ are each independently a hydrocarbon group having 1 to 30 carbon atoms, a hydrocarbon group having 1 to 30 carbon atoms or hydrogen having functionality, preferably a hydrocarbon group having 1 to 10 carbon atoms. , A functional hydrocarbon group having 1 to 10 carbon atoms or hydrogen, more preferably a hydrocarbon group having 1 to 4 carbon atoms or hydrogen, and more preferably hydrogen.

Specific examples of the nitrogen-containing compound represented by the general formula (6) include hydrazides having 1 to 30 carbon atoms or functional hydrocarbon groups having 1 to 30 carbon atoms and derivatives thereof. is there. When R ¹¹ is a hydrocarbon group having 1 to 30 carbon atoms or a hydrocarbon group having 1 to 30 carbon atoms having functionality, and R ^{12 to} R ¹⁴ are hydrogen, the hydrocarbon group having 1 to 30 carbon atoms or the functionality Any of hydrazide having a hydrocarbon group having 1 to 30 carbon atoms, R ¹¹ and R ^{12 to} R ¹⁴ is a hydrocarbon group having 1 to 30 carbon atoms or a hydrocarbon group having 1 to 30 carbon atoms having functionality. When R ^{12 to} R ¹⁴ are hydrogen, N-hydrocarbyl hydrazide having a hydrocarbon group having 1 to 30 carbon atoms or a hydrocarbon group having 1 to 30 carbon atoms having functionality (hydrocarbyl is a hydrocarbon group) Etc.).

  When the ashless friction modifier is used in the lubricating oil composition of the present invention, the content of the ashless friction modifier is preferably 0.01% by mass or more, more preferably 0.1% by mass, based on the total amount of the composition. % Or more, more preferably 0.3% by mass or more, preferably 3% by mass or less, more preferably 2% by mass or less, and still more preferably 1% by mass or less. When the content of the ashless friction modifier is less than 0.01% by mass, the effect of reducing friction due to the addition tends to be insufficient, and when the content exceeds 3% by mass, the effect of an antiwear additive or the like. Tends to be inhibited, or the solubility of the additive tends to deteriorate.

  In the present invention, either one of the organic molybdenum compound or the ashless friction modifier may be used, or both may be used in combination, but it is more preferable to use the ashless friction modifier.

  Examples of metal detergents include alkali metal sulfonates or alkaline earth metal sulfonates, alkali metal phenates or alkaline earth metal phenates, and alkali salts such as alkali metal salicylates or alkaline earth metal salicylates, basic positive salts, or overbased salts. Etc. In the present invention, one or more alkali metal or alkaline earth metal detergents selected from the group consisting of these, particularly alkaline earth metal detergents can be preferably used. In particular, a magnesium salt and / or a calcium salt is preferable, and a calcium salt is more preferably used.

  As the ashless dispersant, any ashless dispersant used in lubricating oils can be used. For example, a mono- or mono-chain having at least one linear or branched alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule or Bisuccinimide, benzylamine having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, polyamine having at least one alkyl group or alkenyl group having 40 to 400 carbon atoms in the molecule, or these And modified products of boron compounds, carboxylic acids, phosphoric acids, and the like. In use, one kind or two or more kinds arbitrarily selected from these can be blended.

  The weight average molecular weight of the ashless dispersant used in the present invention, preferably a bis-type polybutenyl succinimide and / or a derivative thereof, is preferably 3000 or more, more preferably 6500 or more, still more preferably 7000 or more, particularly preferably. Is 8000 or more. When the weight average molecular weight is less than 3000, the molecular weight of the non-polar polybutenyl group is small and the dispersibility of the sludge is small, and the amine part of the polar group, which may become an active site for oxidative degradation, is relatively increased and oxidized. May be less stable. From such a viewpoint, the nitrogen content contained in the ashless dispersant is preferably 3% by mass or less, more preferably 2% by mass or less, particularly preferably 1% by mass or less, preferably 0.1% by mass or more, and more. Preferably it is 0.5 mass% or more. On the other hand, from the viewpoint of preventing deterioration of low temperature viscosity characteristics, the weight average molecular weight is preferably 20000 or less, and particularly preferably 15000 or less. Here, the weight average molecular weight means that two columns of Tosoh GMHHR-M (7.8 mm ID × 30 cm) are used in series on a Waters 150-CALC / GPC apparatus, and the solvent is tetrahydrofuran, temperature. 23 ° C., flow rate of 1 mL / min, sample concentration of 1 mass%, sample injection amount of 75 μL, and weight average molecular weight in terms of polystyrene measured with a detector differential refractometer (RI).

  Examples of the antioxidant include ashless antioxidants such as phenols and amines, and metal antioxidants such as copper and molybdenum. Specifically, for example, as a phenol-based ashless antioxidant, 4,4′-methylenebis (2,6-di-tert-butylphenol), 4,4′-bis (2,6-di-tert- Butylphenol) and the like are amine-based ashless antioxidants such as phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, and dialkyldiphenylamine.

  As the antiwear agent (or extreme pressure agent), any antiwear agent / extreme pressure agent used in lubricating oils can be used. For example, sulfur-based, phosphorus-based, sulfur-phosphorus extreme pressure agents and the like can be used. Specifically, phosphites, thiophosphites, dithiophosphites, trithiophosphites Esters, phosphate esters, thiophosphate esters, dithiophosphate esters, trithiophosphate esters, amine salts thereof, metal salts thereof, derivatives thereof, dithiocarbamate, zinc dithiocarbamate, molybdenum dithiocarbamate, disulfide , Polysulfides, sulfurized olefins, sulfurized fats and oils, and the like. Among these, addition of a sulfur-based extreme pressure agent is preferable, and sulfurized fats and oils are particularly preferable.

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

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

  As the pour point depressant, for example, a polymethacrylate polymer compatible with the lubricating base oil to be used can be used.

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

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

Examples of antifoaming agents include silicone oils having a kinematic viscosity at 25 ° C. of less than 0.1 to 100 mm ² / s, alkenyl succinic acid derivatives, esters of polyhydroxy aliphatic alcohols and long chain fatty acids, methyl salicylates and o. -Hydroxybenzyl alcohol etc. are mentioned.

  When these additives are contained in the lubricating oil composition of the present invention, the content thereof is 0.01 to 10% by mass based on the total amount of the composition.

The kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is preferably 4 to 12 mm ² / s, more preferably 4.5 to 10 mm ² / s, still more preferably 5 to 9 mm ² / s, and particularly preferably 6. ˜8 mm ² / s. If the kinematic viscosity at 100 ° C. is less than 4 mm ² / s, there is a risk of insufficient lubricity, and if it exceeds 12 mm ² / s, the necessary low temperature viscosity and sufficient fuel saving performance may not be obtained. is there.

  The viscosity index of the lubricating oil composition of the present invention is preferably 140 to 300, more preferably 190 to 300, still more preferably 200 to 300, still more preferably 210 to 300, still more preferably 220 to 300, particularly. Preferably it is 230-300, Most preferably, it is 240-300. When the viscosity index of the lubricating oil composition of the present invention is less than 140, it may be difficult to improve fuel economy while maintaining the HTHS viscosity, and further reduce the low temperature viscosity at -35 ° C. May be difficult. In addition, when the viscosity index of the lubricating oil composition of the present invention is 300 or more, low temperature fluidity is deteriorated, and there is a risk of problems due to insufficient solubility of additives and compatibility with sealing materials. There is.

  In addition to the kinematic viscosity and viscosity index at 100 ° C. satisfying the above requirements, the lubricating oil composition of the present invention preferably satisfies the following requirements.

The kinematic viscosity at 40 ° C. of the lubricating oil composition of the present invention is preferably 4 to 50 mm ² / s, preferably 10 to 40 mm ² / s, more preferably 20 to 35 mm ² / s, and particularly preferably 27. ~32mm is a ² / s. If the kinematic viscosity at 40 ° C. is less than 4 mm ² / s, there is a risk of insufficient lubricity, and if it exceeds 50 mm ² / s, the necessary low temperature viscosity and sufficient fuel saving performance may not be obtained. is there.

  The lubricating oil composition of the present invention has an HTHS viscosity at 150 ° C. of preferably 3.5 mPa · s or less, more preferably 3.0 mPa · s or less, and even more preferably 2.8 mPa · s or less. Particularly preferably, it is 2.7 mPa · s or less. Further, it is preferably 2.0 mPa · s or more, preferably 2.3 mPa · s or more, more preferably 2.4 mPa · s or more, particularly preferably 2.5 mPa · s or more, and most preferably 2.6 mPa · s. s or more. The HTHS viscosity at 150 ° C. here refers to the high temperature and high shear viscosity at 150 ° C. defined in ASTM ASTM D4683. When the HTHS viscosity at 150 ° C. is less than 2.0 mPa · s, there is a risk of high vaporization and insufficient lubricity. When it exceeds 3.5 mPa · s, the necessary low-temperature viscosity and sufficient fuel saving Performance may not be obtained.

Since the lubricating oil composition of the present invention has the above-described configuration, it is excellent in fuel economy, low evaporation, and low-temperature viscosity characteristics, and it can be a synthetic oil such as poly-α-olefin base oil and ester base oil, Without using a viscose mineral base oil, while maintaining the HTHS viscosity at 150 ° C., it is possible to achieve both fuel saving and low temperature viscosity at −35 ° C. or lower, and to significantly improve the seizure resistance and wear resistance. . For example, according to the lubricating oil composition of the present invention, when producing SAE0W-20 engine oil, the CCS viscosity at −35 ° C. can be 3500 mPa · s or less. Further, according to the lubricating oil composition of the present invention, the MRV viscosity at −40 ° C. can be set to 7000 mPa · s or less. Incidentally, SAE 0W-20 engine oil viscosity grade of kinematic viscosity at 100 ℃ 5.6mm ² / s or more 9.3mm less than ² / s, 150 HTHS viscosity at ° C. is 2.6 mPa · s or more, CCS at -35 ° C. Although the viscosity is 6200 mPa · s or less and the MRV viscosity at −40 ° C. is 60000 mPa · s or less, it can be manufactured with a particularly low temperature viscosity as described above, and has excellent seizure resistance and wear resistance. An excellent lubricating oil composition can be obtained.

  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 base oil 1]
First, the fraction separated by distillation under reduced pressure 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 component (hereinafter referred to as “WAX1”), which was removed during solvent dewaxing and obtained as slack wax, was used as a base oil for a lubricating base oil. Table 1 shows the properties of WAX1.

  Next, hydroprocessing was performed using WAX1 as a raw material oil and a hydroprocessing catalyst. At this time, the reaction temperature and the liquid space velocity were adjusted so that the decomposition rate of the raw material oil was 5 mass% or more and the sulfur content of the oil to be treated was 10 mass ppm or less. “The decomposition rate of the feedstock is 5% by mass or more” means that the fraction of the treated oil that is lighter than the initial boiling point of the feedstock is 5% by mass or more based on the total feedstock Which is confirmed by gas chromatography.

  Next, about the to-be-processed object obtained by said hydrogenation process, in the temperature range of 315 degreeC-325 degreeC using the zeolite-type hydrodewaxing catalyst adjusted to noble metal content 0.1 to 5 weight%. Hydrodewaxing was performed.

Furthermore, the to-be-processed object (raffinate) obtained by the above hydrodewaxing was hydrorefined using a hydrogenation catalyst. Thereafter, a light component and a heavy component were separated by distillation to obtain a lubricating base oil (base oil 1) having the composition and properties shown in Table 4. In Table 4, the “ratio of components derived from normal paraffin in the urea adduct” is obtained by performing a gas chromatography analysis on the urea adduct obtained in the measurement of the urea adduct value. Yes (the same applies hereinafter).
[Manufacture of base oil 2]
First, an FT wax having a paraffin content of 95% by mass and having a carbon number distribution of 20 to 80 (hereinafter referred to as “WAX2”) was prepared. Table 2 shows the properties of WAX2.

Next, a lubricating oil having the composition and properties shown in Table 4 was obtained by performing hydrotreatment, hydrodewaxing, hydrorefining and distillation in the same manner as base oil 1 except that WAX2 was used instead of WAX1. A base oil (Base oil 2) was obtained.
[Manufacture of base oil 3]
In the production of the base oil 3, a wax component obtained by further deoiling WAX1 (hereinafter referred to as "WAX3") was used as a raw material for the lubricant base oil. Table 3 shows the properties of WAX3.

Next, a lubricating oil having the composition and properties shown in Table 4 was obtained by performing hydrotreatment, hydrodewaxing, hydrorefining and distillation in the same manner as base oil 1 except that WAX3 was used instead of WAX1. A base oil (Base oil 3) was obtained.
[Manufacture of base oil 4]
A lubricating base oil having the composition and properties shown in Table 5 was produced in the same manner as the base oil 2 except that the hydrodewaxing temperature was changed to 300 ° C. or higher and lower than 315 ° C.
[Base oil 5]
As a conventional lubricating base oil, a lubricating base oil having the composition and properties shown in Table 5 was prepared.

(Examples 1-3, Comparative Examples 1-10)
In Examples 1 to 3 and Comparative Examples 1 to 4, the lubricating oil compositions having the compositions shown in Tables 6 and 7 using the lubricating base oils shown in Tables 4 and 5 and the additives shown below (0W- 20 oil) was prepared.
(Additive)
A1: Alkyldiphenylamine B1: Zinc dialkyldithiophosphate (phosphorus content: 7.2% by mass, alkyl group: secondary butyl group or secondary hexyl group mixture)
C1: Ca sulfonate D1: Polybutenyl succinimide (bis type, weight average molecular weight: 8,500, nitrogen content: 0.65% by mass)
E1: polymethacrylate-based viscosity index improver (weight-average molecular weight _M W: 300,000, PSSI = 40 polymethacrylates (alkyl methacrylate mixture (alkyl groups: linear alkyl group having 1 and 12 to 15 carbon atoms) and Dispersed polymethacrylate with dimethylaminoethyl methacrylate as the main structural unit)
F1: polymethacrylate-based viscosity index improver (weight-average molecular weight _M W: 100,000, PSSI = 5 polymethacrylate (alkyl methacrylate mixture (alkyl groups: linear alkyl group having 1 and 12 to 15 carbon atoms) and Dispersed polymethacrylate with dimethylaminoethyl methacrylate as the main structural unit)
F2: polymethacrylate-based viscosity index improver (weight-average molecular weight _M W: 500,000, PSSI = 30 polymethacrylate (alkyl methacrylate mixture (alkyl groups: linear alkyl group having 1 and 12 to 15 carbon atoms) And dispersible polymethacrylate having dimethylaminoethyl methacrylate as the main structural unit)
F3: ethylene-propylene copolymer (weight average molecular weight: 175,000, Hitec-5751 (registered trademark) manufactured by Afton)
F4: Styrene-propylene copolymer (molecular weight: 150,000, styrene / hydrogenated isoprene linear diblock copolymer, Infineum SV151 (registered trademark))
Tables 6 and 7 show various properties of the lubricating oil compositions of Examples 1 to 3 and Comparative Examples 1 to 10. Here, the “seizure load” in Tables 6 and 7 is a seizure load measured by increasing the load with a ratchet after running-in at 500 lbf for 5 minutes using a Falex P / V tester. Means. The “wear amount” in Tables 6 and 7 means the total weight loss of the pin and the block before and after operation for 30 minutes at 1000 lbf, measured in a friction test using a Falex P / V tester.

Claims (3)

A lubricant base oil having a urea adduct value of 4% by mass or less and a viscosity index of 100 or more;
A poly (meth) acrylate having a weight average molecular weight of 200,000 to 400,000;
A lubricating oil composition for an internal combustion engine, comprising:   Hydrocracking / hydroisomerization so that the lube base oil contains a normal paraffin, the urea adduct value of the material to be treated is 4% by mass or less and the viscosity index is 100 or more. 2. The lubricating oil composition for an internal combustion engine according to claim 1, wherein the lubricating oil base oil is obtained by a process of converting into a base oil. The lubricating oil composition for internal combustion engines according to claim 2, wherein the raw material oil contains 50% by mass or more of slack wax obtained by solvent dewaxing of a lubricating base oil.