JP5430522B2 - 4 cycle engine oil base oil and composition - Google Patents

Description

  The present invention relates to a four-cycle engine oil base oil and a four-cycle engine oil composition containing an ester-based lubricating base oil, and more particularly, to prevent scuffing of a valve system even when operated under severe conditions for a long time. And four-cycle engine oil base oil and four-cycle engine oil composition that are extremely excellent in camshaft wear prevention, or in a four-cycle engine oil composition containing an ester-based lubricating base oil and an organic molybdenum compound, camshaft pitching The present invention relates to a 4-cycle engine oil composition that can also improve the prevention performance and a method thereof.

  In recent years, demand for 4-cycle engine oil is extremely strict due to the increasing performance and output of 4-cycle engines and the increasing popularity of motor sports, sports utility vehicles (SUV), and high-performance motorcycles. Is in the situation. In particular, high-performance engines used for racing are pursuing small size, light weight, and high output, and high-speed regions of 3000 to 10000 rpm for four-wheeled vehicles and 6000 to 20000 rpm for motorcycles are regularly used for a long time. Therefore, from the viewpoint of engine durability, there is a demand for a high-performance engine oil with extremely high wear resistance, high reliability, and high safety. However, with the 4-cycle engine oil for motorcycle racing currently on the market, the anti-scuffing performance of the rocker arm pads and the anti-camera performance of the camshaft are not sufficient to withstand harsh driving for long periods of time, and are critical during the race. There is concern about the possibility of causing engine trouble.

  On the other hand, such a high-performance engine is also beginning to be desired to reduce the friction loss of the engine from the viewpoint of increasing the output or reducing the number of refueling during the race. In order to improve fuel economy performance, it is common to reduce the friction loss in the boundary lubrication region by setting the viscosity of the engine oil low, reducing the stirring resistance, and blending the organic molybdenum compound (for example, Patent Document 1). -3), and high-performance engine oils blended with organomolybdenum compounds include fully-synthetic or semi-synthetic engines that use poly-α-olefin base oils or mineral oil base oils and ester base oils in combination. Oil is known (see, for example, Patent Documents 3 to 8).

  However, ester base oils tend to hinder the effects of anti-wear agents such as zinc dithiophosphate and organic molybdenum compounds due to their strong polarity. Especially when salicylates are blended, ester base oils or anti-wear agents. In the fuel-saving four-cycle engine oil composition containing an organic molybdenum compound, the camshaft pitching is significantly deteriorated. It has been found that the prevention performance is significantly deteriorated. Therefore, in the conventional ester base oil-containing 4-cycle engine oil, the compounding amount of the ester base oil is inevitably limited to about 20% by mass or less.

  On the other hand, the additive is consumed over a long period of use, and it is difficult to maintain its performance for a long time. Therefore, even when no additive is added, the 4-cycle engine has high stability and high anti-wear performance. It is also necessary to optimize the oil base oil.

  Therefore, optimization of a four-cycle engine base oil that can maintain the valve system scuffing and camshaft wear prevention performance even in a severe operation for a long time without adding an additive, and such a base A four-cycle engine oil composition with an additive blend that maximizes the characteristics of the oil and provides superior performance, and achieves both fuel saving performance and camshaft pitching prevention performance at an extremely high level. There was a need for the development of a possible four-cycle engine oil composition.

JP-A-8-302378 Japanese Patent Laid-Open No. 2001-181664 JP-A-5-279686 U. S. Pantet. 4,208,292 U. S. Patent No. 4,259,254 U. S. Patent No. 4,428,861 JP-A-10-195474 JP 2001-348591 A JP-A-8-183985

  The present invention has been made in view of the above circumstances. That is, the first problem of the present invention is that it has a stable oil film retention property under harsh conditions for a long time without blending additives, rocker arm pad scuffing prevention performance, camshaft wear prevention performance and cam It is to provide a 4-cycle engine oil base oil that is extremely excellent in preventing shaft pitching.

  The second object of the present invention is to further prevent rocker arm pad scuffing and camshaft wear even when various additives are added to the 4-cycle engine base oil, particularly when a salicylate detergent is added. It is to provide a four-cycle engine oil composition that can be improved.

  In addition to the above-mentioned problems, the third problem is a 4-cycle having a friction reducing effect and an excellent anti-pitching performance of a camshaft even when a molybdenum compound is mixed with a base oil containing a large amount of ester base oil. It is to provide an engine oil composition.

  As a result of intensive studies to solve the above problems, the present inventor has solved the above problems by a composition comprising a 4-cycle engine oil base oil containing a specific ester base oil and a specific friction modifier. The inventors have found that the present invention can be accomplished and have completed the present invention.

That is, according to the first aspect of the present invention, (A) 10 to 90% by mass of an ester-based lubricant base oil and (B) a mineral oil-based lubricant base oil and / or a poly-α-olefin system based on the total base oil amount It is a 4-cycle engine oil base oil comprising 90 to 10% by mass of a lubricant base oil, and the (A) ester base oil has (A-1) a kinematic viscosity at 100 ° C. of 20 to 50 mm ² / s. , A copolymer of a dicarboxylic acid ester and an α-olefin having 3 to 20 carbon atoms, and (A-2) a polyhydric alcohol having a kinematic viscosity of ² to 50 mm ² / s at 100 ° C. It is a 4-cycle engine oil base oil comprising 5 to 60% by mass of an ester with a fatty acid.

  By adopting the configuration as described above, the first object of the present invention is a rocker arm pad which has a stable oil film retention even when used under severe conditions for a long time without blending additives. It is possible to provide a four-cycle engine oil base oil that is extremely excellent in scuffing prevention performance, camshaft wear prevention performance, and camshaft pitching prevention performance.

  In the 4-cycle engine oil base oil of the first aspect, the component (A-2) is an ester of a polyol selected from trimethylolpropane, pentaerythritol, and neopentyl glycol and a carboxylic acid having 6 to 10 carbon atoms. It is preferable.

  The second aspect of the present invention is the ashless friction modifier having (C) at least one alkyl group or alkenyl group having 6 to 30 carbon atoms in the four-cycle engine base oil of the first aspect. , (D) 1 or 2 types selected from (phosphite) phosphate compounds and (E) organomolybdenum compounds, each containing 0.01 to 5% by mass based on the total amount of the composition. Is a four-cycle engine oil composition.

  In the engine oil composition of the second aspect, the component (C) is preferably (C-1) a fatty acid amide represented by the following general formula (1).

（一般式（１）において、Ｒ１は炭素数６〜３０のアルキル基又はアルケニル基を示し、Ｒ２は水素を示す）

(In the general formula (1), R1 represents an alkyl group or alkenyl group having 6 to 30 carbon atoms, and R2 represents hydrogen)

  In the engine oil composition according to the second aspect, (F) zinc dithiophosphate, (G) a metal detergent, (H) an ashless dispersant, (I) an ashless antioxidant, and (J) a viscosity. The index improver is preferably blended in the range of 0.01 to 15% by mass based on the total amount of the composition.

  When configured as described above, it is preferable that the (G) metal detergent is (G-1) an alkaline earth metal salicylate detergent.

  In such a configuration, the second problem of the present invention can be solved. That is, when various additives are blended with the 4-cycle engine oil base oil of the first aspect, the performance of preventing rocker arm pad scuffing and camshaft wear can be further improved even when a salicylate detergent is blended. It is possible to provide a four-cycle engine oil composition that can be produced.

  According to the third aspect of the present invention, (A) 10 to 90% by mass of an ester-based lubricant base oil and (B) a mineral oil-based lubricant base oil and / or a poly-α-olefin-based lubricant based on the total amount of the base oil. A four-cycle engine oil composition comprising (E) an organomolybdenum-based compound in a four-cycle engine oil base oil comprising 90 to 10% by mass of a base oil, and (C-1) represented by the following general formula (1) A 4-cycle engine oil composition comprising 0.01 to 5% by mass of a fatty acid amide based on the total amount of the composition.

（一般式（１）において、Ｒ１は炭素数６〜３０のアルキル基又はアルケニル基を示し、Ｒ２は水素を示す）

(In the general formula (1), R1 represents an alkyl group or alkenyl group having 6 to 30 carbon atoms, and R2 represents hydrogen)

  In this way, the third problem of the present invention, the effect of reducing friction and the excellent anti-pitching performance of the camshaft, can be achieved even when a molybdenum compound is blended with a base oil containing a large amount of ester base oil. A four-cycle engine oil composition can be provided.

  In the four-cycle engine oil composition of the third aspect, it is preferable to further blend (D) (sub) phosphate compound in an amount of 0.01 to 5 mass% based on the total amount of the composition.

  The 4-cycle engine oil composition according to the second and third aspects is preferably used for a motorcycle or a race engine.

  The fourth aspect of the present invention is based on the total amount of base oil (A) 10 to 90% by mass of ester-based lubricant base oil, and (B) mineral oil-based lubricant base oil and / or poly-α-olefin-based lubricant. A 4-cycle engine oil composition comprising (E) an organomolybdenum compound in an amount of 0.01 to 5% by mass based on the total amount of the composition in a 4-cycle engine oil base oil comprising 90 to 10% by mass of an oil base oil, (C-1 ) Improvement method of camshaft pitting prevention performance of fuel-saving four-cycle engine oil, characterized by blending 0.01 to 5% by mass of fatty acid amide represented by general formula (1) below based on the total amount of the composition It is in.

（一般式（１）において、Ｒ１は炭素数６〜３０のアルキル基又はアルケニル基を示し、Ｒ２は水素を示す）

(In the general formula (1), R1 represents an alkyl group or alkenyl group having 6 to 30 carbon atoms, and R2 represents hydrogen)

  In the improvement method of the fourth aspect, it is preferable to further blend (D) (sub) phosphate compound in an amount of 0.01 to 5% by mass based on the total amount of the composition.

  The component (G) is preferably (G-1) an alkaline earth metal salicylate detergent.

  The four-cycle engine oil base oil of the present invention has excellent valve-scuffing, wear and pitching prevention performance that can withstand severe operation for a long period of time without blending any additives, low phosphorus, It is also possible to obtain a low-ash, low-sulfur, or substantially phosphorus-free, ash-free, and sulfur-free 4-cycle engine oil composition. Further, the four-cycle engine oil composition of the present invention can further improve scuffing and wear prevention performance by blending a specific friction modifier as an essential component. Further, the present invention provides a four-cycle engine oil composition and method for achieving both fuel saving performance and pitching prevention performance at a very high level by selecting an ashless friction modifier even when an organic molybdenum compound is contained. Can be provided.

  Therefore, the 4-cycle engine oil base oil and composition of the present invention are not only useful as a 4-cycle engine oil composition for motorcycles or races, but also as general gasoline engine oil, gas engine oil, diesel engine oil, etc. Useful.

  In addition, scuffing and wear prevention performance, or further, pitching prevention performance, lubricants that require low friction, for example, lubricating oil for drive systems such as automatic or manual transmissions, grease, wet brake oil, hydraulic fluid It can also be suitably used as a lubricating oil such as turbine oil, compressor oil, bearing oil, and refrigeration oil.

  Below, the 4-cycle engine oil base oil and composition of this invention are demonstrated.

The lubricating base oil of the present invention comprises (A) an ester-based lubricating base oil of 10 to 90% by mass and (B) a mineral oil-based lubricating base oil and / or a poly-α-olefin-based lubricating oil based on the total amount of the base oil. This is a 4-cycle engine oil base oil consisting of 90 to 10% by mass of base oil. (A) The content of the ester-based lubricating base oil is preferably 25% by mass or more, more preferably 35% by mass or more, and preferably 75% by mass or less, more preferably based on the total amount of the 4-cycle engine oil base oil. Is 58% by mass or less, and the content of (B) mineral oil base oil and / or poly-α-olefin base oil is preferably 25% by mass or more, more preferably 42% by mass or more. Yes, preferably 75% by mass or less, more preferably 65% by mass or less. The ester-based lubricating base oil is (A-1) a copolymer having a kinematic viscosity at 100 ° C. of 20 to 50 mm ² / s and a copolymer of a dicarboxylic acid ester and an α-olefin having 3 to 20 carbon atoms. %, And (A-2) an ester-based lubricating base oil of a polyhydric alcohol and a fatty acid having a kinematic viscosity at 100 ° C. of ² to 50 mm ² / s, preferably 5 to 60% by mass.

  Specific examples of the component (A-1) include compounds represented by the following general formula (2).

Here, R ¹ represents a linear or branched alkyl group, and R ^{2 to} R ⁵ may be the same or different, and each represents hydrogen, a linear or branched alkyl group, and a formula —R ⁶ —CO ₂ R ^7. Or an ester group represented by the formula —CO ₂ R ⁸ (R 6 represents a linear or branched alkylene group, R ⁷ and R ⁸ may be the same or different, Any one of R ^{2 to} R ⁵ is the ester group, and X and Y may be the same or different and each represents a positive number.

  Here, the structure represented by the following general formula (3) in the general formula (2) is derived from an α-olefin, and the α-olefin has 3 to 20 carbon atoms, More preferably, those having 6 to 18 carbon atoms are used.

  Specific examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1 -Tridedecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicocene and the like can be mentioned. Moreover, the structure represented by the following general formula (4) in the general formula (2) is derived from a dicarboxylic acid ester.

  Specific examples of the dicarboxylic acid include maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid and the like. The alcohol preferably has 1 to 20 carbon atoms, and more preferably has 3 to 8 carbon atoms. Specific examples of the alcohol include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, Examples include heptadecanol, octadecanol, nonadecanol, and eicosanol.

By copolymerizing these α-olefin and dicarboxylic acid ester, the component (A-1) can be obtained. Details of the production method are described in JP-A-58-65246. In this case, the molar ratio of the α-olefin to the dicarboxylic acid ester is preferably X: Y = 1: 9 to 9: 1, and more preferably 3: 7 to 7: 3. Moreover, it is preferable that the average molecular weights of (A-1) component are 1000-3000. Further (A-1) a kinematic viscosity at 100 ° C. components 20 to 50 mm ² / s, it is desirable that preferably 30 to 40 mm ² / s. In the case of less than 20 mm ² / s, or in the case of exceeding 50 mm ² / s, it is difficult to obtain the effects of the present invention, which is not preferable.

  The component (A-1) is preferably a copolymer of dibutyl maleate and an α-olefin having 6 to 18 carbon atoms, preferably 10 to 18 carbon atoms.

  The mixing ratio of the component (A-1) is 5% by mass or more, preferably 10% by mass or more, particularly preferably 15% by mass, and preferably 30% by mass or less, based on the total amount of the 4-cycle engine oil base oil. Is 25% by mass or less, particularly preferably 18% by mass or less. When it is less than 5% by mass, it is difficult to obtain the excellent effect of the present invention, and when it exceeds 30% by mass, it is not preferable because the solubility of the additive is deteriorated and the storage stability is poor.

  The component (A-2) in the 4-cycle engine oil base oil of the present invention is an ester of a polyhydric alcohol and a fatty acid. Specifically, for example, a polyol such as trimethylolpropane, pentaerythritol, neopentylglycol and carbon Esterification of a polyol ester obtained by an esterification reaction with a fatty acid having 2 to 20 or an alcohol having 2 to 18 carbon atoms such as 2-ethylhexyl alcohol or isodecyl alcohol and a divalent fatty acid having 2 to 20 carbon atoms Examples include diesters obtained by the reaction. The polyol ester may be added with an alkylene oxide such as ethylene oxide or propylene oxide.

  As this fatty acid, those having 2 to 20 carbon atoms are preferably used, those having 6 to 18 carbon atoms are preferably used, those having 6 to 12 carbon atoms are more preferably used, and those having 6 to 10 carbon atoms are particularly preferred. Preferably used. The fatty acid may be linear or branched. Specifically, for example, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, hexanoic acid, Isohexanoic acid, heptanoic acid, isoheptanoic acid, octanoic acid, isooctanoic acid, nonanoic acid, isononanoic acid, decanoic acid, isodecanoic acid, undecanoic acid, isoundecanoic acid, lauric acid, isolauric acid, tridecanoic acid, isotridecanoic acid, myristic acid, iso Myristic acid, pentadecanoic acid, isopentadecanoic acid, palmitic acid, isopalmitic acid, heptadecanoic acid, isoheptadecanoic acid, oleic acid, stearic acid, isothearic acid, nonadecanoic acid, isononadecanoic acid, eicosanoic acid, isoeicosanoic acid, adipic acid, azelaic acid, And sebacic acid. In the present invention, a straight chain is preferable.

Further (A-2) a kinematic viscosity at 100 ° C. components 2 to 50 mm ² / s, it is desirable that preferably 3 to 20 mm ² / s, in particular 4 to 8 mm ² / s. When it is less than 2 mm ² / s, or when it exceeds 50 mm ² / s, the composition becomes too high in viscosity, and there is concern about deterioration of fuel saving performance due to an increase in stirring resistance.

  The component (A-2) is preferably a polyol ester from the viewpoint of excellent solubility and heat resistance of the additive and easy maintenance of oil film retention over a long period of time. Trimethylolpropane or pentaerythritol and a carbon number of 6 to Particularly preferred are esters of 12 fatty acids, preferably C6-10 fatty acids, especially tetraesters of pentaerythritol and C6-C10 linear and / or branched carboxylic acids.

  The mixing ratio of the component (A-2) is 5% by mass or more, preferably 20% by mass or more, particularly preferably 30% by mass, preferably 60% by mass or less, based on the total amount of the 4-cycle engine oil base oil. Is 50% by mass or less, particularly preferably 40% by mass or less. When the amount is less than 5% by mass, the solubility and storage stability of the additive are inferior. When the amount exceeds 60% by mass, the influence on the rubber sealant is large, which is not preferable.

The component (B) in the 4-cycle engine oil base oil in the present invention is a mineral oil base oil and / or a poly-α-olefin base oil.
Specifically, as the mineral base oil, the lube oil fraction obtained by distilling the atmospheric residue obtained by atmospheric distillation of the crude oil is subjected to solvent removal, solvent extraction, and hydrogenation. Examples include those refined by one or more treatments such as cracking, solvent dewaxing, hydrorefining, etc., or base oils produced by isomerizing wax isomerized mineral oil, GTL WAX (gas-tuly wax) it can.

  The total aromatic content of the mineral oil base oil is not particularly limited, but the upper limit of the total aromatic content is preferably 10% by mass, more preferably 8% by mass, The lower limit is preferably 0% by mass, more preferably 2% by mass, and particularly preferably 3% by mass. By making the total aromatic content of the base oil as described above, a composition excellent in oxidation stability and friction reducing effect can be obtained, and by setting it to 2% by mass or more, particularly the component (A-1) Even when blended in an amount of 10% by mass or more, excellent solubility of the additive can be imparted, and it can be used more preferably than the poly-α-olefin-based lubricating base oil. The total aromatic content here means an aromatic fraction content measured in accordance with ASTM D2549. Usually, this aromatic fraction contains alkylbenzene, alkylnaphthalene, anthracene. Phenanthrene, and alkylated products thereof, compounds in which four or more benzene rings are condensed, or compounds having heteroaromatics such as pyridines, quinolines, phenols, naphthols, and the like.

  The sulfur content in the mineral oil base oil is not particularly limited, but is preferably 0.2% by mass or less, more preferably 0.05% by mass or less, and 0.005% by mass. It is particularly preferred that By reducing the sulfur content of the mineral oil base oil, it is possible to further reduce the adverse effects on the oxidation stability and the exhaust gas purification catalyst, and it is possible to obtain a composition having excellent long drain properties.

  Specific examples of the poly-α-olefin-based lubricating base oil include oligomers of α-olefins having 4 to 16 carbon atoms, preferably 8 to 12 carbon atoms such as 1-octene oligomers and 1-decene oligomers. Or those hydrides etc. are mentioned.

  In the present invention, the component (B) can be used as a mineral oil base oil or a poly-α-olefin base oil alone or in combination, for example, one or more mineral oil bases. Oils, mixed oils of one or more poly-α-olefin-based lubricating base oils, one or more mineral oil-based lubricating base oils and one or more poly-α-olefin-based lubricating base oils, etc. Can do.

Although there is no restriction | limiting in particular in the kinematic viscosity of the said (B) component, It is preferable that the kinematic viscosity in 100 degreeC is 20 mm < ² > / s or less, More preferably, it is 10 mm < ² > / s or less. On the other hand, the kinematic viscosity is preferably ^{2 mm} 2 / s or more, more preferably ^{3 mm} 2 / s or more. When the kinematic viscosity at 100 ° C. of the lubricating base oil exceeds 20 mm ² / s, the low-temperature viscosity characteristic deteriorates. On the other hand, when the kinematic viscosity is less than 1 mm ² / s, an oil film is formed at the lubrication site. Insufficient lubrication results in poor lubricity and increases the evaporation loss of the lubricating base oil, which is not preferable.

  Further, the amount of NOACK evaporation of the component (B) is not particularly limited, but is preferably 16% by mass or less, more preferably 13% by mass or less, and particularly preferably 10% by mass or less. When the NOACK evaporation amount of the component (B) exceeds 16% by mass, not only the evaporation loss of the base oil is large, but also the sulfur compound, phosphorus compound, or metal component in the composition is deposited on the exhaust gas purification device together with the base oil. Furthermore, there is a risk of increasing frictional resistance and oxidative degradation due to the concentration of the additive, making it difficult to maintain the valve system scuffing and wear prevention. In addition, the NOACK evaporation amount here is measured based on CEC L-40-T-87.

  The viscosity index of the component (B) is not particularly limited, but the value is preferably 100 or more, more preferably 120 so that excellent viscosity characteristics from low temperature to high temperature and excellent low friction properties can be obtained. That's it. If the viscosity index is less than 100, the low-temperature viscosity characteristics deteriorate, which is not preferable.

  The content of the component (B) in the 4-cycle engine oil base oil of the present invention is 90 to 10% by mass, preferably 75% by mass or less, more preferably 65% by mass or less, 25% by mass or more, 42 It is at least mass%. By making content of (B) component into the said range, it is excellent in heat resistance and oxidation stability, can demonstrate the effect of an additive more easily, and can obtain the composition excellent also in storage stability.

The kinematic viscosity at 100 ° C. of the 4-cycle engine base oil of the present invention is not particularly limited, but the value is preferably 20 mm ² / s or less so that oil film retention performance and fuel saving performance can be obtained. It is more preferably 16 mm ² / s, particularly preferably 12 mm ² / s, more preferably 4 mm ² / s or more, further preferably 5 mm ² / s or more, 6 mm ² / s. Particularly preferred is s or more.
The viscosity index of the 4-cycle engine oil base oil of the present invention is not particularly limited, but the value is 100 or more so that excellent viscosity characteristics from low temperature to high temperature and excellent low friction properties can be obtained. Is more preferable, and 120 or more is more preferable. If the viscosity index is less than 100, the low-temperature viscosity characteristics deteriorate, which is not preferable.

  In addition, the NOACK evaporation amount of the four-cycle engine oil base oil of the present invention is not particularly limited, but to suppress oil consumption and maintain stable and excellent performance even after a long and severe operation. The value is preferably 16% by mass or less, more preferably 13% by mass or less, and particularly preferably 10% by mass or less.

  The four-cycle engine oil base oil of the present invention includes other synthetic lubricant base oils as required, for example, aromatic synthetics such as polybutene or hydrides thereof, alkylnaphthalene, alkylbenzene, and aromatic esters. Oil or a mixture thereof can be blended.

  The four-cycle engine base oil comprising the above components (A) and (B) of the present invention prevents rocker arm scuffing even when it is operated under harsh conditions for a long time without blending various additives. And anti-camshaft wear resistance, and excellent thermal oxidation stability and cleanliness. So-called phosphorus-free, ash-free, and sulfur-free oils that are harsh as 4-cycle engine oil compositions. Although it can be applied to an engine operated under conditions, various additives can be blended to further impart various performances as necessary, and the blending amount can be minimized. For example, based on the total amount of the composition, the phosphorus content is 0.05% by mass or less, or a composition containing substantially no phosphorus content, the metal content is 1.0% by mass or less in terms of sulfated ash content, or 0.5 A composition containing substantially no metal or less than mass%, a sulfur content of 0.1 mass% or less, or 0.05 mass% or less, or substantially not containing sulfur (0.001 mass%) The following composition) and the like can be obtained, and the influence on the exhaust gas after-treatment device such as a three-way catalyst, a NOx storage reduction catalyst, an oxidation catalyst, and a DPF can be minimized.

  The 4-cycle engine oil composition of the present invention has (C) at least one alkyl group or alkenyl group having 6 to 30 carbon atoms in the 4-cycle engine oil base oil composed of the component (A) and the component (B). It is preferable to blend at least one selected from an ashless friction modifier, (D) a (phosphite) ester compound, and (E) an organic molybdenum compound.

  As the component (C), specifically, known ashless friction modifiers used for lubricating oils can be used. For example, the alkyl group or alkenyl group having 6 to 30 carbon atoms, particularly 12 to 18 carbon atoms. These include fatty acid amides, fatty acid esters, aliphatic ethers, aliphatic amine compounds, etc. having at least one alkyl group or alkenyl group in the molecule, all for preventing scuffing of rocker arm pads and preventing camshaft wear. Useful.

  Examples of the fatty acid amide include compounds represented by the following general formula (1).

In the general formula (1), R1 represents an alkyl group or alkenyl group having 6 to 30 carbon atoms, preferably 12 to 18 carbon atoms, and R2 is hydrogen or 1 to 30 carbon atoms, preferably hydrogen or 12 to 18 carbon atoms. Represents an alkyl group or an alkenyl group. When an organomolybdenum compound is blended in the composition, R ² is particularly preferably hydrogen from the viewpoint that the camping prevention performance of the camshaft can only be enhanced.

Specific examples of the fatty acid amide include oleyl amide, oleyl oleyl amide, stearyl amide, stearyl stearyl amide and the like, and oleyl amide and stearyl amide in which R ² is hydrogen are particularly preferable.

  Specific examples of the fatty acid ester include glycerol monooleate, glycerol dioleate, glycerol trioleate, glycerol monostearate, glycerol distearate, sorbitan monooleate, sorbitandiolate, sorbitan trioleate, and sorbitan monoester. Examples include stearate, and glycerin monooleate is particularly preferable.

  Specific examples of the aliphatic ether include glycerol monooleyl ether and glycerol monostearyl ether, and glycerol monostearyl ether is particularly preferable.

  Further, as the aliphatic amine, linear or branched, preferably linear aliphatic monoamine having 6 to 30 carbon atoms, linear or branched, preferably linear aliphatic polyamine, Or the alkylene oxide adduct of these aliphatic amines can be illustrated.

  In the present invention, as the component (C), it is preferable to blend at least one ashless friction modifier selected from the fatty acid amides, fatty acid esters, and aliphatic ethers.

  In the present invention, one or two or more compounds arbitrarily selected from these (C) friction modifiers can be contained in any amount. Usually, the content is 0.01 to 5.0% by mass on the basis of the lubricating oil composition, but good solubility, storage stability, scuffing for the four-cycle engine oil base oil of the present invention. In order to obtain the prevention property and the wear prevention property, it is preferably 0.1 to 1.0% by mass, particularly preferably 0.2 to 0.5% by mass. When content of (C) component exceeds 5.0 mass%, it is inferior in the solubility to the 4-cycle engine oil base oil of this invention, and when less than 0.01 mass%, the addition effect of (C) component is Since it cannot be obtained, each is not preferable.

  The component (D) in the present invention is a (phosphite) ester compound, and specifically, for example, an alkyl group, alkenyl group or aryl group having 3 to 30 carbon atoms, particularly an alkyl group having 8 to 18 carbon atoms. Examples thereof include phosphoric acid monoesters having 1 to 3 groups or alkenyl groups, phosphoric acid diesters, phosphoric acid triesters, phosphorous acid monoesters, phosphorous acid diesters, phosphorous acid triesters, and amine salts thereof. Among them, phosphites and amine salts of phosphites are preferable examples.

  (D) The compounding quantity of a component is 0.01-5 mass%, Preferably it is 0.1-2 mass%.

  The component (E) in the present invention is an organomolybdenum compound, and known organomolybdenum compounds generally used for lubricating oils can be used. Specific examples include molybdenum dithiocarbamate compounds, molybdenum dithiophosphate compounds, molybdenum-succinimide complexes, molybdenum-amine complexes, and the like. In the present invention, a molybdenum dithiocarbamate compound and a molybdenum dithiophosphate compound are preferable, and a molybdenum dithiophosphate is preferable in terms of preventing rocker arm pad scuffing, and molybdenum dithiophosphate is preferable in terms of preventing camshaft wear. Carbamate is preferred. Of these, molybdenum dithiophosphate exhibits a specific friction reducing effect on a base oil containing a large amount of an ester base oil such as the 4-cycle engine oil base oil of the present invention. (E) Although the compounding quantity of a component is 0.01-5 mass% normally, it is preferable that it is 0.003-0.2 mass% in molybdenum element conversion amount, 0.005-0.1 mass% It is more preferable that it is 0.01-0.06 mass%.

  In the 4-cycle engine oil composition of the present invention, (F) zinc dithiophosphate, (G) metal-based detergent, (H) ashless dispersant, and (I) ashless antioxidant are 0.01 to 15 respectively. It is preferable to contain in the range of mass%.

  The component (F) in the four-cycle engine oil composition of the present invention is zinc dithiophosphate, which is a known zinc dithiophosphate generally used for lubricating oils, for example, primary or secondary alkyl having 3 to 18 carbon atoms. A dialkyl or diaryl dithiophosphate zinc having a group, an aryl group can be used. The content of the component (F) is preferably 0.1 to 2% by mass based on the total amount of the composition.

  The component (G) in the four-cycle engine oil composition of the present invention is a metal detergent, and known metal detergents commonly used in lubricating oils such as alkali metal or alkaline earth metal sulfonates, phenates, Salicylates and the like and mixtures thereof can be used. These include not only neutral salts but also (per) basic salts in which calcium carbonate, calcium borate and the like are dispersed, and the base number thereof is usually 0 to 500 mgKOH / g, preferably 50 to 400 mgKOH / g, Especially preferably, it is 150-300 mgKOH / g. The content of the component (G) is preferably 0.1 to 15% by mass, more preferably 0.5 to 5% by mass, based on the total amount of the composition.

  For salicylate detergents, monoalkyl salicylates having a base number of 50 to 300 mgKOH / g and one alkyl group or alkenyl group having 10 to 30 carbon atoms are generally commercially available. In the case of using a system detergent, (F) the action of an anti-wear agent such as zinc dithiophosphate or the excellent effect of the 4-cycle engine oil base oil of the present invention is inhibited, and the anti-wear performance of rocker arm scuffing and camshaft Even when a salicylate-based detergent having one alkyl group or alkenyl group having 10 to 19 carbon atoms, which is easily deteriorated, is used, the above-mentioned wear is suppressed by satisfying the base oil and other configurations of the present invention. The resulting composition can be obtained. In particular, it is preferable to use a salicylate detergent having a base number of 150 to 300 mgKOH / g, which is (over) basified with calcium carbonate or calcium borate. Of course, a sulfonate detergent and / or a phenate detergent, a salicylate detergent having one alkyl group or alkenyl group having 20 to 30 carbon atoms, or an alkyl group or alkenyl group selected from 1 to 30 carbon atoms. The two salicylate-based detergents can be used particularly preferably because they hardly inhibit the action of the antiwear agent.

  The component (H) in the four-cycle engine oil composition of the present invention is an ashless dispersant and has a known ashless dispersant generally used in lubricating oils, for example, an alkyl group or alkenyl group having a number average molecular weight of 700 to 3,500. Examples thereof include monosuccinimide, bissuccinimide, benzylamine, amine and derivatives of these boron compounds, phosphorus compounds, sulfur compounds, oxygen-containing compounds and the like. In the present invention, it is preferable to use mono- or bissuccinimide and / or a boron-modified compound thereof, particularly bissuccinimide and / or a boron-modified compound thereof. The content of the component (H) in the 4-cycle engine oil composition of the present invention is preferably 0.1 to 15% by mass, more preferably 1 to 10% by mass, and still more preferably 2 based on the total amount of the composition. -5% by mass, particularly preferably 3-4% by mass. When a boron-modified compound is used, its content is usually 0.005-0.2% by mass in terms of boron, preferably 0.01- 0.06% by mass.

  Component (I) in the four-cycle engine oil composition of the present invention is an ashless antioxidant. Any of phenolic compounds and amine compounds that are generally used in lubricating oils can be used. For example, alkylphenols such as 2,6-di-tert-butyl-4-methylphenol Bisphenols such as methylene-4,4-bis (2,6-di-tert-butyl-4-methylphenol), octyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) Ester-phenols such as propionate and octyl-3- (3-methyl-5-tert-butyl-4-hydroxyphenyl) propionate, naphthylamines such as phenyl-α-naphthylamine, dialkyldiphenylamines and phenothiazines can be used. . The content of component (I) is preferably 0.1 to 5% by mass, more preferably 0.5 to 2% by mass.

  The four-cycle engine oil composition of the present invention is a known additive generally used for lubricating oil, for example, a rust inhibitor, a corrosion inhibitor, in order to further enhance the performance or to impart another performance. , A viscosity index improver, a pour point improver, a demulsifier, an antifoaming agent, and the like can be arbitrarily added. As the rust inhibitor, for example, alkenyl succinic acid, alkenyl succinic acid ester, polyhydric alcohol ester, petroleum sulfonate, dinonyl naphthalene sulfonate and the like can be used.

  As the corrosion inhibitor, for example, benzotriazole, thiadiazole, and imidazole compounds can be used.

  As the viscosity index improver, a non-dispersed viscosity index improver or a dispersed viscosity index improver can be used. Specifically, a non-dispersed or dispersed polymethacrylate or olefin copolymer, or polyisobutene, polystyrene, An ethylene-propylene copolymer, a styrene-diene copolymer and a hydride thereof can be used. These weight average molecular weights are generally 5,000 to 1,000,000, but in order to further improve fuel economy performance, the weight average molecular weight is 100,000 to 1,000,000, preferably 200,000 to It is desirable to use the above viscosity index improvers which are 900,000, particularly preferably 400,000 to 800,000. When the composition of the present invention is used for a four-cycle engine for a motorcycle or a race engine, it is desirable to use a polymethacrylate having the above molecular weight, preferably a dispersed polymethacrylate, in order to enhance the low friction performance.

  The content of the viscosity index improver is preferably 0.1 to 15% by mass, more preferably 1 to 10% by mass.

  As the pour point depressant, for example, a polymethacrylate polymer, an alkylated aromatic compound, a fumarate-vinyl acetate copolymer, an ethylene-vinyl acetate copolymer, and the like that are 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, and polyoxyethylene alkyl naphthyl ether.

  As the antifoaming agent, for example, silicone compounds such as dimethyl silicone and fluorosilicone can be used.

  Although the addition amount of these additives is arbitrary, the content of the antifoaming agent is usually 0.0005 to 0.01% by mass and the content of the viscosity index improver is 0.05 to 15 based on the total amount of the composition. The content of the mass%, the corrosion inhibitor is 0.005 to 0.2 mass%, and the contents of the other additives are each selected in the range of 0.01 to 15 mass%.

The four-cycle engine oil composition of the present invention has a kinematic viscosity at 100 ° C. of 5.6 mm ² / s, preferably 9.3 mm ² / s, more preferably by blending the above-mentioned various additives. Is preferably 12.5 mm ² / s, particularly preferably 16.5 mm ² / s, and the upper limit is 21.9 mm ² / s, preferably 18 mm ² / s. By setting the kinematic viscosity at 100 ° C. of the composition within the above range, high oil film retention and oil consumption can be suppressed, and stable performance can be maintained over a long period of time.

  Hereinafter, the four-cycle engine oil base oil and the four-cycle engine oil composition according to the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. . (Examples 1-14, Comparative Examples 1, 3-5)

  A four-cycle engine base oil and composition (Examples 1 to 14) according to the present invention shown in Table 1 and a composition for comparison shown in Table 2 (Comparative Example 1) were prepared. Moreover, 4-cycle engine oils A to C (Table 2, Comparative Examples 3 to 5) marketed for motorcycle racing were prepared. These compositions were subjected to a valve-operated wear test in accordance with JASO M 328-95 without replacement for 200 hours, which is twice the normal 100 hours, and scuffing scores of rocker arm pads after 200 hours, cam Shaft wear and camshaft pitching scores were measured. If the scuffing score of the rocker arm pad is 8.0 or more, particularly 9.0 or more, the camshaft wear amount is 10 μm or less, particularly 5 μm or less, and the camshaft pitching score is 8.0 or more, particularly 9.0 or more, it is extremely excellent. Performance.

  In addition, some sample oils are evaluated as a reference value by a cylinder-on-disk test method in which the curved side of a cylinder is brought into contact with a flat disk by line contact using an Optimol SRV reciprocating friction tester. Went. This friction test is said to reflect the friction condition of the cam, and is a widely used technique especially for evaluating fuel-saving engine oil. The test conditions were an oil temperature of 80 ° C., a load of 400 N, a frequency of 50 Hz, and an amplitude of 1.5 mm, and the friction coefficient was measured.

  First, the above-mentioned JASO valve system test was carried out on high-performance four-cycle engine oils A to C (Comparative Examples 3 to 5) marketed in Japan, and the results are shown in Table 2.

  Although these commercial oils have a camshaft pitching score of 9.0 or more, the scuffing score of the rocker arm pad is 3 or less, or severe scuffing occurs when 100 hours have elapsed since the operation time is half. The amount was also high, and there was nothing that could withstand harsh long-term driving.

(1) First problem: Rocker arm pad scuffing, camshaft wear and camshaft pitching prevention performance of 4-cycle engine oil base oil The 4-cycle engine oil base oil shown in Example 1 is an additive such as an antiwear agent. It can be seen that the rocker arm pad is extremely excellent in scuffing prevention performance, camshaft wear prevention performance and camshaft pitching prevention performance even though it is not blended at all. In addition, it is thought that the base oil of Example 1 contributes to the outstanding effect of this invention that NOACK evaporation amount is 6 mass% and oil consumption is very small.

(2) Second problem: Rocker arm pad scuffing and camshaft wear prevention performance improvement of the above base oil A composition comprising (C-1) oleylamide in addition to the 4-cycle engine oil base oil of Example 1 ( Example 2), a composition in which (F) zinc dithiophosphate, (G) metal detergent, (H) ashless dispersant, (I) viscosity index improver, etc. were further blended with the composition of Example 2 (implementation) Example 3) shows that the rocker arm pad scuffing and camshaft wear prevention performance is further improved.

  Moreover, the composition which mix | blended 1 type (s) or 2 or more types chosen from various (C) ashless type | system | group friction modifiers, (D) (phosphite) type | system | group compound, and (E) organomolybdenum compound (Example 4- Similarly, it can be seen that 14) improves the rocker arm scuffing prevention performance and cam wear prevention performance of the four-cycle engine oil base oil of the present invention.

  In addition, instead of the monoalkyl salicylate having an alkyl group having 14 to 18 carbon atoms used in the composition of the example, a monoalkyl salicylate having an alkyl group having 20 to 40 carbon atoms or a carbon number of 1 to 30 is selected. When dialkyl salicylates having two alkyl groups are used, better results are obtained.

  Moreover, the composition (comparative example 1) which mix | blended various additives with the 4-cycle engine oil base oil (all are outside this application prescription | regulation range) which consists of (A-1) component and (A-2) component in this invention, Even when heated and stirred, the additive did not dissolve and clouded, and the next day after preparation, a precipitate was generated, which was poor in practicality as a 4-cycle engine oil base oil.

(3) Third problem: camshaft pitching prevention performance The composition obtained by blending the (E) organomolybdenum compound with the 4-cycle engine base oil of Example 1 prevents rocker arm pad scuffing and camshaft wear as described above. Although the performance is extremely excellent, especially when only molybdenum dithiophosphate is blended as a friction modifier (Example 5), the camshaft pitching score is extremely deteriorated to 2.6, and (D) Even if (sub) phosphate is used in combination, the same score is improved only to 7.0 (Example 7). In addition, when only molybdenum dithiocarbamate is blended as a friction modifier (Example 6), the pitching score is excellent at 8.5, but worse than the case of only base oil (Example 1), Even if (D) (sub) phosphate is used in combination, the score is 8.4 (Example 9), and the anti-pitching performance is not improved. Further, even when (C-1) oleylamide alone is blended with the base oil of Example 1 (Example 2), the anti-pitting performance is not improved.

  On the other hand, when molybdenum dithiocarbamate and (C-1) oleylamide were used in combination (Example 10), the same score was improved from 8.5 to 9.4, and (D) (sub) phosphate ester When used together (Example 11), the same score improves to the highest score of 10.0. When molybdenum dithiophosphate, (C-1) oleylamide, and (D) (phosphorous) ester were used in combination (Example 8), the same score was improved to 9.7, and the composition of the present invention was improved. It can be seen that the fuel-saving engine oil is useful for extremely improving the pitching prevention performance.

  In addition, it replaces with (C-1) oleylamide of Example 11, and is excellent in rocker arm pad scuffing and camshaft wear prevention performance (C-2) glycerol monooleate, (C-3) glycerol monostearyl ether (C-4) When oleyl oleylamide is used (Examples 12 to 14), it can be seen that the anti-pitching performance does not improve or rather deteriorates. (C) Among the ashless friction modifiers , (C-1) is the only useful component for improving the anti-pitching performance.

Claims (10)

A 4-cycle engine oil composition comprising (A) 25 to 90% by mass of an ester-based lubricant base oil and (B) 75 to 10% by mass of a mineral oil-based lubricant base oil based on the total amount of the base oil,
The (A) ester base oil is based on the total amount of base oil,
(A-1) 5-30 mass% copolymer of dicarboxylic acid ester and C3-C20 alpha olefin whose kinematic viscosity in 100 degreeC is 20-50 mm < ² > / s, and (A-2) 100 degreeC. kinematic viscosity at the Ri ester 5-60 wt% Tona of polyhydric alcohols and fatty acids which are 2 to 50 mm ² / s,
The 4-cycle engine oil composition, wherein the component (A-2) is an ester of a polyol selected from trimethylolpropane, pentaerythritol, and neopentyl glycol and a carboxylic acid having 6 to 10 carbon atoms. Thing . The content of the (A) ester-based lubricant base oil is 75% by mass or less based on the total amount of the base oil,
The 4-cycle engine oil composition according to claim 1, wherein the content of the (B) mineral oil-based lubricating base oil is 25% by mass or more based on the total amount of the base oil. And (C) an ashless friction modifier having at least one alkyl group or alkenyl group having 6 to 30 carbon atoms, (D) a (sub) phosphate compound, and (E) an organic molybdenum compound. 1 type or 2 types or more are each contained 0.01 to 5 mass% on the basis of the total amount of the composition ,
The 4-cycle engine oil composition according to claim 1 or 2 . The 4-cycle engine oil composition according to claim 3, wherein the component (C) is (C-1) a fatty acid amide represented by the following general formula (1).

(In the general formula (1), R ¹ represents an alkyl group or alkenyl group having 6 to 30 carbon atoms, and R ² represents hydrogen.) Furthermore, (F) zinc dithiophosphate, (G) metal-based detergent, (H) ashless dispersant, (I) ashless antioxidant, and (J) viscosity index improver are each 0.01% based on the total amount of the composition. The 4-cycle engine oil composition according to claim 3 or 4, which is contained in a range of -15 mass%. The four-cycle engine oil composition according to claim 5, wherein the (G) metallic detergent is (G-1) an alkaline earth metal salicylate detergent. The four-cycle engine oil composition according to any one of claims 3 to 6, which is used for a motorcycle or a race engine. ( E) The 4-cycle engine oil composition according to claim 1 or 2 containing 0.01 to 5% by mass of an organomolybdenum compound based on the total amount of the composition, (C-1) represented by the following general formula (1) fuel-efficient four-cycle engine oils of the camshaft pitching prevention performance improvement method, which comprises mixing 0.01 to 5 wt% of the total amount of the composition of the fatty acid amide.

(In the general formula (1), R ¹ represents an alkyl group or alkenyl group having 6 to 30 carbon atoms, and R ² represents hydrogen) The (D) (sub) phosphate compound is blended in an amount of 0.01 to 5% by mass based on the total amount of the composition, and the camshaft pitting prevention of fuel-saving four-cycle engine oil according to claim 8 How to improve performance. 9. The four-cycle engine oil composition further contains (G) a metal detergent, and the component (G) is (G-1) an alkaline earth metal salicylate detergent. Or a method for improving the camshaft pitching prevention performance of the fuel-saving four-cycle engine oil according to 9.