WO2015146396A1 - Engine oil composition - Google Patents

Abstract

Provided is an engine oil composition which can achieve both excellent fuel-saving performance and excellent wear resistance. The composition comprises a lubricant oil base oil having a specified property, both a star polymer and a polymer having a specific nitrogen-containing group as essential viscosity index improvers, and an amide compound and/or an imide compound as an essential friction modifier, and can be used particularly suitably as a diesel engine oil.

Description

Engine oil composition

The present invention relates to an engine oil composition that is excellent in fuel saving performance, and particularly excellent in both fuel saving performance and wear resistance.

In recent years, as a countermeasure to environmental problems such as global warming, fuel efficiency has been demanded for engine oil. Fuel economy improvement technology using engine oil includes technology that reduces friction in the fluid lubrication region by lowering the viscosity and technology that reduces friction in the boundary lubrication region by blending a friction reducer. It is done.
However, excessively low viscosity leads to shortage of oil film strength, which causes problems such as adverse effects on engine durability and increased friction in the boundary lubrication region. This is a problem common to both gasoline and diesel engines, but particularly in diesel engines, the adverse effect of lowering the viscosity of engine oil is significant.

In Patent Documents 1 to 3, a specific viscosity index improver is contained in a lubricating base oil having a viscosity index of 120 or more as an engine oil having a constant viscosity under high temperature and high shear and good fuel economy performance. Engine oil is disclosed.

JP 2010-095662 A JP 2010-095663 A JP 2010-095664 A

Although the engine oils according to Patent Documents 1 to 3 have a certain fuel consumption reduction effect, they are still not satisfactory.
The subject of this invention is providing the engine oil composition which was excellent in the fuel-saving performance, and was excellent in abrasion resistance.

As a result of diligent research on the above problems, the inventors of the present invention have a lubricant base oil having a specific property, a polymer having a star polymer and a nitrogen-containing group as a viscosity index improver, and an amide compound, an imide compound as a friction modifier, Alternatively, the inventors have found that by containing a mixture of both compounds, excellent wear resistance and fuel saving effect can be expressed at the same time, and the present invention has been completed.

According to the present invention, a lubricating base oil having a saturation content of 70% by mass or more and a viscosity index of 90 or more and 160 or less, (A) a star polymer A-1 and a weight average molecular weight of 200,000 or more, 400, There is provided an engine oil composition comprising polymer A-2 having a nitrogen-containing group of 000 or less and (B) at least one of an amide compound and an imide compound.
The star polymer is preferably a polymer having a core which is a polyalkenyl compound and 4 to 15 arms bonded to the core.
Further, according to the present invention, a lubricating base oil having a saturated content of 70% by mass or more and a viscosity index of 90 or more and 160 or less, (A) a star polymer A-1 and a weight average molecular weight of 200,000 or more, 400 There is provided the use of a composition comprising a polymer A-2 having a nitrogen-containing group of 1,000 or less and (B) at least one of an amide compound and an imide compound in the production of engine oil.
Further, according to the present invention, a lubricating base oil having a saturation content of 70% by mass or more and a viscosity index of 90 or more and 160 or less, (A) a star polymer A-1 and a weight average molecular weight of 200,000 or more, 400 A composition comprising a polymer A-2 having a nitrogen-containing group of 1,000 or less and (B) at least one of an amide compound and an imide compound is circulated in an engine engine as an engine oil. A method for suppressing fuel consumption of an engine such as a diesel engine is provided.

The engine oil composition of the present invention contains a specific polymer containing a star polymer in a lubricating base oil having a specific property and a specific wear modifier, so that it has excellent fuel efficiency and extremely good resistance to resistance. Abrasion can be exhibited at the same time.

Hereinafter, the present invention will be described in detail.
The base oil of the engine oil composition of the present invention is a lubricating base oil having a saturated content of 70% by mass or more and a viscosity index of 90 or more and 160 or less (hereinafter sometimes simply referred to as a base oil).

The saturated content of the base oil is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. In particular, it is most preferable that almost all is saturated, specifically 99% by mass or more. The upper limit is 100% by mass. When the saturated content is less than 70% by mass, the oxidation stability is not sufficient for use under high temperature and high shear lubrication conditions, and the performance of the present invention cannot be realized due to poor viscosity-temperature characteristics.
The content of the saturated component of the base oil means a mass% value measured in accordance with ASTM D2007-11.

The viscosity index of the base oil is preferably 110 or more, more preferably 120 or more, still more preferably 125 or more, and the upper limit is 160 or less. When the viscosity index is less than 90, not only the viscosity-temperature characteristics, thermal oxidation stability and volatilization prevention properties are deteriorated, but also the friction coefficient tends to increase, and the wear prevention properties tend to decrease. When the viscosity index exceeds 160, the low-temperature viscosity characteristics tend to decrease.
The viscosity index means a viscosity index measured according to JIS K 2283-1993.

The base oil% Cp is preferably 60 or more, and more preferably 70 or more. Moreover, 100 or less is preferable and 95 or less is more preferable. The% Cp means a percentage (%) with respect to the total number of carbon atoms constituting the paraffin in the base oil, and is measured in accordance with ASTM D3238.
The% C _N of the base oil is preferably 40 or less, more preferably 30 or less. Moreover, 1 or more is preferable and 3 or more is more preferable. The% C _N denotes the percentage (%) to the total number of carbon atoms of the carbon atoms constituting the naphthene ring in the base oil, measured according to ASTM D3238.
% C _A is preferably 10 or less of the base oil with 2 or less being more preferred. Moreover, 0 or more are preferable. The% C _A denotes the percentage (%) to the total number of carbon atoms of the carbon atoms constituting the aromatic ring in the base oil, measured according to ASTM D3238.

The base oil used in the present invention includes mineral oil base oil or synthetic oil base oil. These may be used alone or in combination of two or more.

Mineral oil base oils include, for example, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation and vacuum distillation, and solvent removal, solvent extraction, hydrocracking, hydroisomerization, solvent dewaxing, catalytic dewaxing. Examples include paraffinic mineral oil obtained by refining one kind of refining processes such as wax, hydrorefining, sulfuric acid washing, and clay treatment alone or in combination of two or more, or normal paraffinic mineral oil and isoparaffinic mineral oil. It is done.
In particular, hydrocracking lube oil fractions recovered from atmospheric distillation bottom oil and vacuum distillation equipment, and solvent dewaxing and catalytic desorption of the product or lube oil fractions recovered from the product by distillation or the like. Hydrocracked mineral oil obtained by performing a dewaxing treatment such as wax or by distillation after the dewaxing treatment is particularly preferred. Among these, those subjected to contact dewaxing treatment are more preferable.

The pour point of the mineral base oil is preferably −12.5 ° C. or less, more preferably −15 ° C. or less. Further, it is preferably higher than −35 ° C., more preferably −30 ° C. or higher, further preferably −25 ° C. or higher, and particularly preferably −20 ° C. or higher. This is because if the pour point is higher than −12.5 ° C., the characteristics at low temperatures deteriorate, and if it is −35 ° C. or lower, a sufficient viscosity index cannot be obtained. The pour point means a pour point measured in accordance with JIS K 2269-1987.

The NOACK value (NOACK evaporation) in the mineral oil base oil is preferably 15% by mass or less. The NOACK value means an evaporation loss amount (mass%) measured according to ASTMＡD 5800-95.

The sulfur content of the mineral oil base oil is not particularly limited, but the sulfur content in the base oil is preferably 100 mass ppm or less from the viewpoint of further improving thermal and oxidation stability and reducing sulfur content. 50 mass ppm or less is more preferable, 10 mass ppm or less is still more preferable, and 5 mass ppm or less is especially preferable. This sulfur content is a value measured according to JIS 5S-38-2003.

The content of aromatics in mineral base oils is not particularly limited, but the content of aromatics in base oils is 30% by mass or less from the viewpoint of further improving thermal and oxidation stability and reducing sulfur content. Is preferably 10% by mass or less, more preferably 2% by mass or less, and particularly preferably 1% by mass or less. If it exceeds 30% by mass, the oxidation stability is insufficient and the viscosity-temperature characteristics are liable to deteriorate when used under high temperature and high shear lubrication conditions, and the effects of the present invention may not be exhibited.

Synthetic oil base oils include, for example, poly α-olefin or hydride thereof, isobutene oligomer or hydride thereof, isoparaffin, alkylbenzene, alkylnaphthalene, ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl Diesters such as adipate, di-2-ethylhexyl sebacate, polyol esters such as trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol-2-ethylhexanoate, pentaerythritol pelargonate, 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 α-olefin oligomer or co-oligomer such as a 1-octene oligomer having 2 to 32 carbon atoms, preferably 6 to 16 carbon atoms, a decene oligomer, an ethylene-propylene co-oligomer, and the like. A hydride is mentioned.

In both mineral and synthetic oils, the base oil has a kinematic viscosity at 100 ° C. of preferably 1 mm ² / s or more, more preferably 2 mm ² / s or more, still more preferably 3 mm ² / s or more, and 3.5 mm ² / s. The above is particularly preferable. On the other hand, it is preferably 10 mm ² / s or less, more preferably 5 mm ² / s or less, particularly preferably 4.5 mm ² / s. If the 100 ° C. kinematic viscosity exceeds 10 mm ² / s, the low-temperature viscosity characteristics may deteriorate, and sufficient fuel economy may not be obtained. If it is less than 1 mm ² / s, an oil film is formed at the lubrication point. Is insufficient, the lubricity is inferior, and the evaporation loss of the engine oil composition may increase.
The kinematic viscosity at 100 ° C. indicates the kinematic viscosity at 100 ° C. as defined in ASTM D-445.

Mineral, any synthetic oil-based, kinematic viscosity is preferably at least 8 mm ² / s at 40 ° C. of the base oil, more preferably at least 10 mm ² / s, still more preferably at least 12 mm ² / s. On the other hand, it is preferably 45 mm ² / s or less, more preferably 40 mm ² / s or less, and still more preferably 36 mm ² / s or less. Kinematic viscosity at 40 ° C. is poor in lubricity due its insufficient oil film formation at lubricating sites and less than 8 mm ² / s, also there is a possibility that the evaporation loss of the engine oil composition is increased, the 45 mm ² / s If it exceeds, the low-temperature viscosity characteristics deteriorate, and there is a risk that sufficient fuel saving performance cannot be obtained.
The kinematic viscosity at 40 ° C. indicates the kinematic viscosity at 40 ° C. as defined in ASTM D-445.

The engine oil composition of the present invention comprises a star polymer A-1 and a polymer A having a nitrogen-containing group having a weight average molecular weight of 200,000 or more and 400,000 or less as an essential component (A) of the viscosity index improver. -2.

The star polymer A-1 means a polymer having a shape in which a plurality of arms extend outward so as to form a star shape from a molecular center called a core.
The star polymer is preferably a polymer having a core which is a polyalkenyl compound and four or more arms bonded to the core. The number of arms coupled to the core is more preferably 5 or more, and even more preferably 6 or more. The number of arms is preferably 20 or less, and more preferably 15 or less.
If the number of arms is less than 4, the shear stability is not sufficient, the viscosity decreases with the passage of time of use, and the inherently required viscosity may not be ensured. On the other hand, if the number of arms exceeds 20, the viscosity is not sufficiently lowered under high shear, and there is a possibility that the fuel saving performance that is the object of the present invention cannot be ensured.

The core-forming monomer constituting the polyalkenyl compound, which is the preferred core, is preferably a monomer having two or more double bonds such as divinylbenzene or polyvinyl aliphatic compound, and particularly preferably divinylbenzene. The arm is a polymer of an arm forming monomer. Examples of the arm forming monomer include aliphatic dienes having two double bonds such as butadiene and isoprene. The arm has a polymer chain extending from the double bond portion in the polyalkenyl compound that is a polymer of the core-forming monomer, and the double bond remaining after the copolymerization reaction is usually hydrogenated ( Hydrogenated).

The arm structure is preferably one in which an aromatic monomer or aliphatic monomer such as styrene or alkene is bonded to the end of a hydrogenated polymer chain by block polymerization. More preferably, a structure in which polystyrene is present at the terminal is preferable. Furthermore, a structure in which polystyrene is present at the ends of all the arms in the star polymer is preferable.
It is preferable that almost all the double bond portions of the arms are hydrogenated. Such a hydrogenated arm is sometimes referred to as a hydrogenated polydiene, including terminal polystyrene.

When the above polystyrene is contained, the content thereof is preferably 2 mol% or more, more preferably 3 mol% or more, based on the total amount of the star polymer. Moreover, 10 mol% or less is preferable, Furthermore, 7 mol% or less is more preferable. If the polystyrene content is less than 2 mol%, a sufficient decrease in high-temperature shear viscosity may not be obtained, and if it is more than 10 mol%, it may be difficult to obtain sufficient solubility in the base oil. .

The weight average molecular weight of the arm in the star polymer is usually 5,000 to 600,000, more preferably 10,000 to 500,000, and still more preferably 10,000 to 300,000. This is because the shear stability is good and the wear resistance is excellent.

The weight average molecular weight of the star polymer is preferably 10,000 to 1,000,000, more preferably 100,000 to 800,000, still more preferably 300,000 to 600,000. This is because the shear stability is good.
The weight average molecular weight can be measured under the following conditions for both the star polymer A-1 and the polymer A-2 described later.
Measuring device: Alliance 2695 manufactured by Waters
Column: Tosoh GMH6 × 2 (book)
Solvent: Tetrahydrofuran Detector: RI
Standard substance: Polystyrene Measurement conditions: Flow rate 1 mL / min, sample concentration 2.0 mass%, implantation amount 100 μL

The star polymer has a PSSI (Permanent Shear Stability Index) of preferably 45 or less, more preferably 40 or less. When PSSI exceeds 45, the shear stability deteriorates, so that it is necessary to increase the initial kinematic viscosity, which may deteriorate the fuel economy. Further, when PSSI is less than 1, the effect of improving the viscosity index when dissolved in the lubricating base oil is small, and not only the fuel economy and low temperature viscosity characteristics are inferior, but also the cost may increase.
The above “PSSI” conforms to ASTM D 6022-01 (Standard Practice for Calculation of Permanent Shear Stability Index) and is measured by ASTM D 6278-02 (Test Method 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 obtained.

The method for producing the star polymer is not particularly limited. For example, after radical polymerization of divinylbenzene, which is a core-forming monomer, is performed, radical polymerization is similarly performed on diene starting from a double bond existing in the formed core. Followed by hydrogenation and terminal polystyrene formation. Note that either polystyrene formation or hydrogenation of the arm end may be performed first.
Alternatively, after forming a polymer of an arm having a reaction origin at the terminal, it is reacted with a core-forming monomer, and the formation of the core and the bonding of the arm are performed simultaneously, or after the formation of the core and arm polymers, respectively, the reaction origin A method of reacting each other can be employed.
More specifically, for example, US Pat. No. 4,116,917, US Pat. No. 4,141,847, US Pat. No. 4,346,193, US Pat. No. 4,409,120, or JP 2002-504589A, The method disclosed in Japanese Patent No. 129835 can be applied.
Various commercial products can also be used as the star polymer A-1.

The content ratio of the star polymer A-1 in the engine oil composition of the present invention is preferably at least 4% by mass, more preferably 5% by mass or more, based on the total amount of the engine oil composition. On the other hand, 20 mass% or less is preferable, More preferably, it is 15 mass% or less, More preferably, it is 10 mass% or less. When the content is less than 4% by mass, the high temperature high shear viscosity (HTHS viscosity) at 100 ° C. and 1 × 10 ⁶ s ⁻¹ , which is a source of fuel saving effect, is maintained at 100 ° C. and 1 × 10 The high-temperature high shear viscosity at ⁷ s ^-1 cannot be lowered, and if the content exceeds 20% by mass, the shear stability may be deteriorated.

The polymer A-2 having a nitrogen-containing group having a specific weight average molecule (hereinafter sometimes abbreviated as polymer A-2), which is an essential component of the viscosity index improver, is a compound containing nitrogen described later And other compounds.

The polymer A-2 has a weight average molecular weight (M _W ) of 200,000 or more, preferably 250,000 or more. Moreover, it is 400,000 or less, Preferably it is 380,000 or less, More preferably, it is 360,000 or less. When the weight average molecular weight is less than 200,000, there is a possibility that sufficient wear prevention performance cannot be obtained. In addition, when the weight average molecular weight exceeds 400,000, the effect of increasing the viscosity becomes too large, which may be inferior in fuel saving and low temperature viscosity characteristics, and further, shear stability and solubility in lubricating base oil. , Storage stability may be deteriorated.

The nitrogen content in the polymer A-2 is preferably 0.01 to 1.0% by mass based on the total amount of the polymer A-2, more preferably 0.05% by mass or more, and particularly preferably 0.1% by mass or more. . Moreover, 0.5 mass% or less is especially preferable. If it is less than 0.01% by mass, the wear resistance that is the object of the present invention cannot be achieved, and if it exceeds 1.0% by mass, there is a concern that oxidation stability may be concerned.
The PSSI of the polymer A-2 is preferably 60 or less, more preferably 55 or less, and still more preferably 50 or less. If PSSI is 60 or less, the shear stability is better and the fuel economy is further improved.
Further, PSSI is preferably 1 or more. The reason is that the effect of improving the viscosity index when dissolved in the lubricating base oil is sufficiently exhibited, and the fuel economy and low temperature viscosity characteristics are improved.

Polymer A-2 includes, for example, poly (meth) acrylate, hydride of styrene-diene copolymer, ethylene-α-olefin copolymer or hydride thereof, polyisobutylene or hydride thereof, styrene-maleic anhydride ester copolymer, polyalkyl It can be obtained by copolymerizing a nitrogen-containing compound with a non-nitrogen-containing polymerizable compound such as styrene and a (meth) acrylate-olefin copolymer.

Poly (meth) acrylate will be described below as an example of a nitrogen-free polymerizable compound used in the production of the polymer A-2. Here, poly (meth) acrylate means, for example, a generic name of those selected from the group consisting of polyacrylates, polymethacrylates, copolymers of acrylates and methacrylates, and mixtures thereof. Good.
As the polymer A-2 in the case of using this poly (meth) acrylate, the following configuration can be exemplified. That is, a (meth) acrylate monomer represented by the formula (1) (hereinafter referred to as “Compound M-1”) and at least one compound selected from the formulas (2) and (3) (hereinafter, “ Examples thereof include poly (meth) acrylates having a nitrogen-containing group in the molecule, which are copolymerized with “Compound M-2” and “Compound M-3”.

In the formula (1), R ¹ represents a hydrogen atom or a methyl group, and R ² represents a linear or branched hydrocarbon group having 1 to 18 carbon atoms.

In the formula (2), R ³ represents a hydrogen atom or a methyl group, R ⁴ represents an alkylene group having 1 to 18 carbon atoms, E ¹ represents an amine residue containing 1 to 2 nitrogen atoms and 0 to 2 oxygen atoms. Indicates a group or a heterocyclic residue. a is 0 or 1;

In formula (3), R ⁵ 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.

In the formula (2) or (3), the groups represented by E ¹ and E ² specifically include a dimethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, an anilino group, and a toluidino group. , Xylidino group, acetylamino group, benzoylamino group, morpholino group, pyrrolyl group, pyrrolino group, pyridyl group, methylpyridyl group, pyrrolidinyl group, piperidinyl group, quinonyl group, pyrrolidonyl group, pyrrolidono group, imidazolino group, pyrazino group, etc. Can be illustrated.

Preferable examples of compound M-2 or M-3 are specifically dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-methyl-5-vinylpyridine, morpholinomethyl methacrylate, Examples thereof include morpholinoethyl methacrylate, N-vinylpyrrolidone and a mixture thereof.

There is no particular limitation on the copolymerization molar ratio of the compound M-2 or M-3, or both of these (hereinafter referred to as M2 + M-3) and the compound M-1, but in the copolymer The molar ratio of M-1: M-2 + M-3 is preferably about 99: 1 to 80:20, more preferably 98: 2 to 85:15, and still more preferably 95: 5 to 90:10.

Another example of a nitrogen-free polymerizable compound for obtaining the polymer A-2 is a hydride of a styrene-diene copolymer. The copolymer is also a copolymer obtained by using M2 + M-3 in addition to styrene and diene as comonomers. Specifically, as the diene, butadiene, isoprene and the like are preferable, and isoprene is particularly preferable. Hydrogenation is carried out after copolymerization.

Another example of the nitrogen-free polymerizable compound for obtaining the polymer A-2 is an ethylene-α-olefin copolymer. The copolymer is also copolymerized using M2 + M-3 in addition to ethylene and α-olefin as a comonomer. Specific examples of the α-olefin include propylene, isobutylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, and 1-dodecene.

The viscosity index improver in the engine oil composition of the present invention contains two types of polymers, the star polymer A-1 and the polymer A-2, which are the above-mentioned component (A) as essential components. Other viscosity index improvers may be included as long as they are not impaired.
Examples of the other viscosity index improvers include ester group-containing viscosity index improvers and compounds corresponding to the above exemplified polymer A-2, which do not copolymerize nitrogen-containing compounds. Poly (meth) acrylate is preferable. In view of maximizing the effects of the present invention, the viscosity index improver is preferably only the component (A).

The ratio (M _w / M _n : polydispersity) of the weight average molecular weight (M _w ) and the number average molecular weight (M _n ) of the star polymer A-1 in the component (A), and the M _w / Mn (polydispersity) is preferably 5.0 or less, more preferably 4.0 or less, still more preferably 3.5 or less, and particularly preferably 3.0 or less. Further, M _w / M _n is preferably 1.0 or more, more preferably 2.0 or more, still more preferably 2.5 or more, and particularly preferably 2.6 or more. When M _w / M _n exceeds 5.0 or less than 1.0, there is a concern that the improvement effect of solubility and viscosity-temperature characteristics may be lowered, and sufficient storage stability and fuel saving performance can be maintained. There is a risk of disappearing.

The content of component (A) (star polymer A-1 + polymer A-2) is preferably 0.1 to 50% by mass, more preferably 0.5 to 20% by mass, based on the total amount of the engine oil composition. The amount is preferably 1.0 to 15% by mass, particularly preferably 1.5 to 12% by mass. If the content is less than 0.1% by mass, the low temperature characteristics may be insufficient, and if it exceeds 50% by mass, the shear stability of the composition may be deteriorated.

When the engine oil composition of the present invention contains a viscosity index improver other than the component (A), the content of the other viscosity index improver is 10% by mass or less based on the total amount of the engine oil composition. Is preferable, more preferably 5% by mass or less, and still more preferably 3% by mass or less.

The engine oil composition of the present invention contains the component (B) as an essential component, and this component (B) is a friction modifier specifically selected from the group consisting of amide compounds, imide compounds and mixtures thereof. is there. As the amide compound, fatty acid amide is preferable, and as the imide compound, fatty acid imide is preferable, and those derived from linear fatty acid are particularly preferable.

Specific examples of fatty acid amides include fatty acid amides having one nitrogen atom and at least one alkyl group or alkenyl group having 10 to 30 carbon atoms. The fatty acid amide includes, for example, a fatty acid having an alkyl group or an alkenyl group having 10 to 30 carbon atoms or an acid chloride thereof, only ammonia, a hydrocarbon group having 1 to 30 carbon atoms or a hydroxyl group-containing hydrocarbon group in the molecule. It is obtained by reacting with an amine compound contained in Particularly preferred is a fatty acid amide obtained by reacting ammonia with a fatty acid having an alkyl group or alkenyl group having 12 to 24 carbon atoms and having an amide group at the molecular end.

Specific examples of fatty acid amides include lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, coconut oil fatty acid amide, synthetic mixed fatty acid amides having 12 to 13 carbon atoms, and mixtures thereof. Can be mentioned. These fatty acid amides are particularly preferable because they are excellent in wear prevention effect in addition to friction reduction effect.

Examples of other amide compounds include oleic hydrazide, dodecanoic hydrazide, tridecanoic hydrazide, tetradecanoic hydrazide, pentadecanoic hydrazide, hexadecanoic hydrazide, heptadecanoic hydrazide, octadecanoic hydrazide, and olein exemplified in International Publication No. 2005037967. Alkyl groups having 12 to 24 carbon atoms such as acid hydrazide (C ₁₇ H ₃₃ —C (═O) —NH—NH ₂ ) and erucic acid hydrazide (C ₂₁ H ₄₁ —C (═O) —NH—NH ₂ ) Or hydrazide compounds having an alkenyl group, and acid-modified derivatives such as boric acid-modified derivatives hydrazide, semicarbazides such as oleyl semicarbazide, oleyl urea, dodecyl urea, tridecyl urea, tetradecyl urea, pentadecyl urea, hexadecyl Urea having alkyl group or alkenyl group having 12 to 24 carbon atoms such as urea, heptadecyl urea, octadecyl urea, oleyl urea (C ₁₈ H ₃₅ —NH—C (═O) —NH ₂ ), and their boric acid modification Examples thereof include acid-modified derivatives such as derivatives, ureides such as oleyl ureido, allophane amides such as oleyl allophanic amide, and derivatives thereof.

As another form of the amide compound, an amide compound having a hydroxyl group, a carboxylic acid group, or both functional groups in the same molecule can be given. Examples thereof include a hydroxyl group-containing fatty acid amide obtained by reacting a fatty acid having an alkyl or alkenyl group having 10 to 30 carbon atoms or an acid chloride thereof with an amine compound having 1 to 30 carbon atoms having a hydroxyl group.
Among these, the compound represented by Formula (4) is preferable.

In the formula (4), R ⁶ is a hydrocarbon group having 1 to 30 carbon atoms, preferably a hydrocarbon group having 10 to 30 carbon atoms, more preferably an alkyl group or alkenyl group having 12 to 24 carbon atoms, particularly preferably carbon. It is an alkenyl group of formula 12-20. R ⁷ is a hydrocarbon group having 1 to 30 carbon atoms or a hydrogen atom. In the case of a hydrocarbon group, it is preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrocarbon group having 1 to 4 carbon atoms. However, particularly preferred is a hydrogen atom. R ⁸ is a hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrocarbon group having 1 to 4 carbon atoms, still more preferably a hydrocarbon group having 1 to 2 carbon atoms, and most preferably a hydrocarbon group having 1 carbon atom. is there.

The compound represented by the formula (4) can be synthesized, for example, by a reaction between a hydroxy acid and an aliphatic amine. Of the hydroxy acids, aliphatic hydroxy acids are preferred, and linear aliphatic α-hydroxy acids are more preferred. In particular, glycolic acid is preferable among α-hydroxy acids. Other preferred specific examples include N-oleoyl sarcosine and the like.

As the imide compound as the component (B), mono- and / or bissuccinimide having one or two linear or branched, preferably branched hydrocarbon groups, succinimide, boric acid Examples thereof include succinimide-modified compounds obtained by reacting one or more selected from phosphoric acid, carboxylic acids having 1 to 20 carbon atoms, and sulfur-containing compounds.

Specific examples of the succinimide include compounds represented by the formulas (5) and (6).

In the formulas (5) and (6), R ⁹ and R ¹⁰ are each independently an alkyl or alkenyl group having 8 to 30 carbon atoms, preferably 12 to 24 carbon atoms, and R ¹¹ and R ¹² are each Individually, an alkylene group having 1 to 4 carbon atoms, preferably 2 to 3 carbon atoms, and R ¹³ represents a hydrogen atom or an alkyl group or alkenyl group having 1 to 30 carbon atoms, preferably 8 to 30 carbon atoms. n is an integer of 1 to 7, preferably an integer of 1 to 3.

The content of the component (B) that is a friction modifier is preferably 0.01 to 10% by mass, preferably 0.1% by mass or more, more preferably 0.3% by mass or more, based on the total amount of the engine oil composition. In addition, it is 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 component (B) is less than 0.01% by mass, the effect of reducing friction due to the addition tends to be insufficient, and when it exceeds 10% by mass, effects such as an anti-wear additive are obtained. It tends to be inhibited or the solubility of the additive tends to deteriorate.

The content of nitrogen atom in the component (B) is preferably 0.0005 to 0.4% by mass, more preferably 0.001 to 0.3% by mass, particularly preferably as content relative to the total amount of the engine oil composition. Is 0.005 to 0.25% by mass. If it is less than 0.0005% by mass, sufficient anti-wear properties may not be obtained, and if it exceeds 0.4% by mass, the solubility in the engine oil composition will be reduced, resulting in precipitation and turbidity. There is a fear.

The engine oil composition of the present invention can contain a metallic detergent.
As metal-based detergents, alkali salts / basic salts such as alkali metal / alkaline earth metal sulfonate, alkali metal / alkaline earth metal phenate, alkali metal / alkaline earth metal salicylate, and alkali metal / alkaline earth metal salicylate Mention may be made of salts. Examples of the alkali metal include sodium and potassium, and examples of the alkaline earth metal include magnesium, calcium and barium. Magnesium or calcium is preferable, and calcium is particularly preferable. These metal detergents may be combined in any combination.

As the alkali metal / alkaline earth metal sulfonate, specifically, an alkali metal / alkyl aromatic sulfonic acid obtained by sulfonating an alkyl aromatic compound usually having a molecular weight of 100 to 1500, preferably 200 to 700 is used. Mention may be made of alkaline earth metal salts. Specific examples of the alkyl aromatic sulfonic acid include so-called petroleum sulfonic acid and synthetic sulfonic acid. In the present invention, it is preferable to use an overbased sulfonate and / or a low basic sulfonate.

The base number of the overbased sulfonate is usually 150 mgKOH / g or more, preferably 200 mgKOH / g or more, more preferably 250 mgKOH / g or more, most preferably 300 mgKOH / g or more, and preferably 350 mgKOH / g or less.
In the overbased sulfonate, the base number of the engine oil composition is usually 2 mgKOH / g or more, preferably 3 mgKOH / g or more, preferably 10 mgKOH / g or less, more preferably 7 mgKOH / g or less, more preferably It is preferable to contain so that it may become 5 mgKOH / g or less. By making the base number 2 mgKOH / g or more, the oxidation stability required for the engine oil composition of the present invention can be improved, and by making it 10 mgKOH / g or less, the amount of ash is reduced, The combustion chamber deposit can be reduced.

In the case of a low basic sulfonate, the base number is usually 50 mgKOH / g or less, preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less, preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g. g or more.
The low basic sulfonate has a base number of the engine oil composition of usually 0.01 mgKOH / g or more, preferably 0.02 mgKOH / g or more, preferably 2 mgKOH / g or less, more preferably 1 mgKOH / g or less. Furthermore, it is preferable to contain so that it may become 0.5 mgKOH / g or less. By making the base number 0.01 mgKOH / g or more, improvement in crankcase cleanliness required for the engine oil composition can be expected, and even if it exceeds 2 mgKOH / g, the effect does not increase and 2 mgKOH / g There is no advantage of containing in excess of g.
The above base number is determined according to JIS K2501 “Petroleum products and lubricants—neutralization number test method”. Means the base number measured by the perchloric acid method according to the above.

Specifically, the alkali metal / alkaline earth metal phenate includes an alkylphenol having at least one linear or branched alkyl group having 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms, the alkylphenol and sulfur. Or an alkali metal / alkaline earth metal salt of a Mannich reaction product of an alkylphenol obtained by reacting the alkylphenol with formaldehyde.
The alkali metal / alkaline earth metal phenate has a base number of usually 150 mgKOH / g or more, preferably 200 mgKOH / g or more, more preferably 250 mgKOH / g or more, and preferably 350 mgKOH / g or less.
The alkali metal / alkaline earth metal phenate has a base number of the engine oil composition of usually 0.3 mgKOH / g or more, preferably 0.7 mgKOH / g or more, more preferably 1 mgKOH / g or more, and preferably 5 mgKOH. / G or less, more preferably 3 mgKOH / g or less, still more preferably 2 mgKOH / g or less. By making the base number 0.3 mgKOH / g or more, the oxidation stability of the engine oil composition of the present invention is improved, and the effect does not increase even if it exceeds 5 mgKOH / g, so that it exceeds 5 mgKOH / g. There is no advantage to contain.

As the alkali metal / alkaline earth metal salicylate, specifically, an alkali metal / alkali of alkyl salicylic acid having at least one linear or branched alkyl group having 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms. Mention may be made of earth metal salts.
The base number of the alkali metal / alkaline earth metal salicylate is usually 150 mgKOH / g or more, preferably 200 mgKOH / g or more, more preferably 250 mgKOH / g or more, particularly preferably 300 mgKOH / g or more, and 350 mgKOH / g or less. Is preferred.
The alkali metal / alkaline earth metal salicylate has a base number of the engine oil composition of usually 2 mgKOH / g or more, preferably 3 mgKOH / g or more, preferably 10 mgKOH / g or less, more preferably 7 mgKOH / g or less, More preferably, the oxidation stability can be expected to be improved by setting the base number to be 2 mgKOH / g or more so as to be 5 mgKOH / g or less, and the ash content is suppressed by being 10 mgKOH / g or less. Reduction of combustion chamber deposit can be expected.

The alkali metal / alkaline earth metal sulfonate, alkali metal / alkaline earth metal phenate, and alkali metal / alkaline earth metal salicylate are not only neutral salts (normal salts) but also low basic salts, basic salts and excess salts. It may be a basic salt (super basic salt) or a mixture thereof.
In the engine oil composition of the present invention, it is preferable to use a combination of an overbased sulfonate, a low basic sulfonate, an overbased phenate, and an overbased salicylate having a base number in the above range. Most preferably, a combination of the three types of metal detergents is such that the base number of the engine oil composition is usually 2 mgKOH / g or more, preferably 3 mgKOH / g or more, preferably 10 mgKOH / g or less, more preferably Is contained at 7 mgKOH / g or less, more preferably 5 mgKOH / g or less. This makes it possible to achieve a balance between cleanliness required for engine oil and fuel efficiency.

When the metal detergent is contained in the engine oil composition of the present invention, the content is preferably 500 ppm by mass or more, more preferably 800 ppm by mass or more in terms of metal elements, based on the total amount of the engine oil composition. More preferably, it is 1000 mass ppm or more. Moreover, Preferably it is 3500 mass ppm or less, More preferably, it is 3000 mass ppm or less, More preferably, it is 2600 mass ppm or less. By making it 500 ppm by mass or more, sufficient base number maintenance and high temperature cleanliness can be expected. On the other hand, by making it 3500 ppm by mass or less, the amount of sulfated ash produced by use is suppressed, and an exhaust gas purification catalyst. It can be expected to prevent clogging of the filter.

The engine oil composition of the present invention can contain an ashless dispersant.
Examples of the ashless dispersant include nitrogen-containing compounds having at least one linear or branched alkyl group or alkenyl group having 40 to 400 carbon atoms or derivatives thereof. Specific examples include succinimide, alkenyl succinimide, and modified products thereof. One or two or more arbitrarily selected from these can be blended.

The carbon number of the alkyl group or alkenyl group of the ashless dispersant is preferably 40 to 400, more preferably 60 to 350. Setting the number of carbon atoms of the alkyl group or alkenyl group to 40 or more suppresses a decrease in solubility in the lubricating base oil, while setting it to 400 or less suppresses deterioration in low-temperature fluidity of the engine oil composition. Is possible. The alkyl group or alkenyl group may be linear or branched, but preferred examples include branched olefins derived from olefin oligomers such as propylene, 1-butene and isobutylene, and ethylene and propylene co-oligomers. An alkyl group and a branched alkenyl group.

Preferred examples of the succinimide include a so-called mono-type succinimide in which succinic anhydride is added to one end of the polyamine, and a so-called bis-type succinimide in which succinic anhydride is added to both ends of the polyamine. In addition, either one of monotype and bis type succinimide may be contained, or both may be contained.

Benzylamine can also be used as another ashless dispersant. Specific examples of preferable benzylamine include compounds represented by the formula (7).
R ¹⁴ —Ph—CH ₂ NH— (CH ₂ CH ₂ NH) _p —H (7)
In the formula (7), R ¹⁴ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably an alkyl group or alkenyl group having 60 to 350 carbon atoms, and Ph represents a phenylene group. p represents an integer of 1 to 5, preferably 2 to 4.

Polyamine can also be used as another ashless dispersant. Specific examples of the polyamine include a compound represented by the formula (8).
R ¹⁵ —NH— (CH ₂ CH ₂ NH) _q —H (8)
In the formula (8), R ¹⁵ represents an alkyl group or alkenyl group having 40 to 400 carbon atoms, preferably an alkyl group or alkenyl group having 60 to 350 carbon atoms. q is an integer of 1 to 5, preferably 2 to 4.

Specific examples of derivatives of the above nitrogen-containing compounds that can be used as ashless dispersants include monocarboxylic acids having 1 to 30 carbon atoms such as fatty acids, oxalic acid, phthalic acid, trimellitic acid, pyromellitic acid, etc. A product obtained by reacting an oxygen-containing compound such as polycarboxylic acid having 2 to 30 carbon atoms or hydroxy (poly) alkylene carbonate to neutralize part or all of the remaining amino group and / or imino group, amidation Examples thereof include a modified compound by an organic acid or the like, or a sulfur-modified compound obtained by allowing a sulfur compound to act on the aforementioned nitrogen-containing compound. Furthermore, a boronated ashless dispersant modified with a boron compound is also included.

The boronated ashless dispersant is a borated version of any ashless dispersant used in lubricating oils. Boronation is generally performed by allowing boric acid or the like to act on the nitrogen-containing compound described above to neutralize part or all of the remaining amino group and / or imino group.
For example, as a method for producing a boronated succinimide, for example, JP-B-42-8013, JP-B-42-8014, JP-A-51-52381, JP-A-51-130408, etc. Is disclosed. Specifically, for example, boric acid, boric acid ester, borate, etc. in the presence of organic solvents such as alcohols, hexane and xylene, light lubricating base oil, polyamine and polyalkenyl succinic acid (anhydride), etc. The boron compound can be mixed and heat-treated under appropriate conditions. The boron content in the boronated succinimide thus obtained can usually be 0.1 to 4.0% by mass.

When the engine oil composition of the present invention contains an ashless dispersant, the content of the ashless dispersant is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass, based on the total amount of the engine oil composition. It is. Furthermore, it is more preferably 2.5% by mass or more, and most preferably 5% by mass or more. By making the content of the ashless dispersant 0.1% by mass or more, the effect of improving friction reduction is sufficiently obtained. On the other hand, by making it 20% by mass or less, the low temperature fluidity of the engine oil composition is deteriorated. It can be greatly suppressed.

When a boronated ashless dispersant such as the boronated succinimide is used, the boron content in the engine oil composition is usually 0.01% by mass or more, preferably 0.02% by mass based on the total amount of the engine oil composition. % Or more, more preferably 0.025 mass% or more, and 0.15 mass% or less, preferably 0.1 mass% or less, particularly preferably 0.05 mass% or less.
In the present invention, it is preferable to contain both a boronated succinimide and a non-borated succinimide as an ashless dispersant. The ratio of the boronated succinimide to the non-borated succinimide is preferably 0.1 or more, more preferably 0.2 or more, and further preferably 0.3 or more. Moreover, 0.6 or less is preferable, 0.5 or less is more preferable, and 0.4 or less is still more preferable. When the ratio is 0.1 or more, the heat resistance and wear resistance effect of the boronated succinimide can be maintained, and when the ratio is 0.6 or less, cleanliness is maintained. Can do.

The engine oil composition of the present invention can contain an antioxidant.
Antioxidants can be used as long as they are commonly used in lubricating oils, such as ashless antioxidants such as phenolic antioxidants and amine antioxidants, and organometallic antioxidants. It is. By adding the antioxidant, the antioxidant property of the engine oil composition can be further improved, and not only the corrosion or corrosion wear prevention performance can be improved, but also the base number maintenance property can be further improved.

Examples of phenolic antioxidants include 4,4′-methylenebis (2,6-di-tert-butylphenol), 4,4′-bis (2,6-di-tert-butylphenol), 4,4 ′. -Bis (2-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-isopropylidenebis (2,6-di-tert-butylphenol), 2,2′-methylenebis (4-methyl-6) -Nonylphenol), 2,2'-isobutylidenebis (4,6-dimethylphenol), 2,2'-methylenebis (4-methyl-6-cyclo (Hexylphenol), 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6- Di-tert-α-dimethylamino-p-cresol, 2,6-di-tert-butyl-4 (N, N′-dimethylaminomethylphenol), 4,4′-thiobis (2-methyl-6-tert) -Butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 2,2'-thiobis (4-methyl-6-tert-butylphenol), bis (3-methyl-4-hydroxy-) 5-tert-butylbenzyl) sulfide, bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, 2,2′-thio- Diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tridecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythrityl- Tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, octadecyl-3- ( Preferred examples include 3,5-di-tert-butyl-4-hydroxyphenyl) propionate and 3-methyl-5-tert-butyl-4-hydroxyphenyl substituted fatty acid esters. You may use these in mixture of 2 or more types.

Examples of amine antioxidants include aromatic amine antioxidants such as phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, and dialkyldiphenylamine. You may use these in mixture of 2 or more types.

The above phenolic antioxidants and amine antioxidants can be used alone, but are preferably combined in combination. As a blending ratio, the amine antioxidant is preferably 10% by mass or more, more preferably 20% by mass or more, and more preferably 40% by mass or more with respect to the total amount of the phenolic antioxidant and the amine antioxidant. Is more preferable. Moreover, 80 mass% or less is preferable, and 60 mass% or less is more preferable.

In the engine oil composition of the present invention, for the purpose of further improving the performance, if necessary, in addition to the above additives, other friction modifiers other than the component (B), and further, an antiwear agent (extra pole) (Also called pressure agent) Corrosion inhibitors, rust inhibitors, demulsifiers, metal deactivators, pour point depressants, rubber swelling agents, antifoaming agents, colorants, etc. You may do it.

Examples of other friction modifiers include friction modifiers selected from organic molybdenum compounds and ashless friction modifiers.
Examples of organic molybdenum compounds include sulfur-containing organic molybdenum compounds such as molybdenum dithiophosphate and molybdenum dithiocarbamate, complexes of molybdenum compounds with sulfur-containing organic compounds or other organic compounds, molybdenum sulfide, and sulfurized molybdenum acid. And a complex of a sulfur-containing molybdenum compound such as alkenyl succinimide.

When the organic molybdenum compound is used, the content is not particularly limited, but is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, particularly preferably 0.01% by mass or more, in terms of molybdenum element, based on the total amount of the engine oil composition. Preferably it is 0.03 mass% or more, Preferably it is 0.2 mass% or less, More preferably, it is 0.1 mass% or less, More preferably, it is 0.08 mass% or less. By setting the content to 0.005% by mass or more, it is possible to maintain the heat and oxidation stability of the engine oil composition, and in particular, it can be expected to maintain excellent cleanliness over a long period of time. On the other hand, when content exceeds 0.2 mass%, the effect corresponding to content will not be acquired and it exists in the tendency for the storage stability of an engine oil composition to fall.

As the ashless friction modifier, any compound usually used as a friction modifier for lubricating oils can be used. For example, an amine compound, a fatty acid ester, a fatty acid amide, a fatty acid, having at least one alkyl group or alkenyl group having 6 to 30 carbon atoms, in particular, a linear alkyl group or linear alkenyl group having 6 to 30 carbon atoms in the molecule, Examples include ashless friction modifiers such as aliphatic alcohols and aliphatic ethers. Moreover, 1 or more types of compounds chosen from the group which consists of a nitrogen-containing compound and its acid modification derivative, and various ashless friction modifiers illustrated by the international publication 2005/037967 pamphlet are mentioned.

When using an ashless friction modifier, the content thereof is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.3% by mass, based on the total amount of the engine oil composition. Further, it is preferably 3% by mass or less, more preferably 2% by mass or less, and further preferably 1% by mass or less. By making the content of the ashless friction modifier 0.01% by mass or more, an effect of reducing friction by adding the ashless friction modifier can be obtained, and by making it 3% by mass or less, the effect of the antiwear additive etc. is affected. The solubility of the additive can be ensured.

As the antiwear agent, any antiwear agent / extreme pressure agent used for lubricating oil can be used. For example, sulfur-based, phosphorus-based, and sulfur-phosphorus extreme pressure agents can be used.
In the present invention, zinc alkyldithiophosphate is effective. Alkyl groups having 3 to 12 carbon atoms are usually used. In the present invention, it is preferable to use a zinc alkyldithiophosphate having a primary alkyl group and a secondary alkyl group in order to balance extreme pressure and oxidation stability. The ratio of primary to secondary is preferably 0.3 or more, more preferably 0.5 or more, and most preferably 0.55 or more. Moreover, 0.8 or less is preferable and 0.7 or less is more preferable. If it is less than 0.3, the oxidation stability may be insufficient, and if it exceeds 0.8, the extreme pressure property may be insufficient. In addition, the combined use of primary and secondary alkyl groups may be within the same zinc alkyldithiophosphate, or may be a mixture of different zinc alkyldithiophosphates.

In the case of using a zinc alkyldithiophosphate, the content thereof is preferably 0.02% by mass or more, more preferably 0.05% by mass, and more preferably 0.08% by mass or more in terms of phosphorus element, based on the total amount of the engine oil composition. Is more preferable. Moreover, 0.2 mass% or less is preferable, 0.15 mass% or less is more preferable, and 0.1 mass% or less is further more preferable. Sufficient extreme pressure property is obtained by setting it as 0.02 mass% or more, and the bad influence to an exhaust-gas aftertreatment apparatus can be suppressed by setting it as 0.2 mass% or less.

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

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

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

Examples of the metal deactivator include imidazoline, pyrimidine derivatives, alkylthiadiazole, mercaptobenzothiazole, benzotriazole or derivatives thereof, 1,3,4-thiadiazole polysulfide, 1,3,4-thiadiazolyl-2,5-bis. Examples include dialkyldithiocarbamate, 2- (alkyldithio) benzimidazole, or β- (o-carboxybenzylthio) propiononitrile.

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

As the pour point depressant, for example, a polymethacrylate polymer compatible with the lubricating base oil to be used can be used. The weight average molecular weight is preferably 150,000 or less, more preferably 100,000 or less, and still more preferably 80,000 or less. Moreover, 20,000 or more are preferable and 40,000 or more are more preferable. By setting it as 150,000 or less, the target product viscosity can be ensured and the function as a pour point depressant can be maintained by setting it as 20,000 or more. When the pour point depressant is contained in the lubricating oil composition of the present invention, the content thereof is usually selected from the range of 0.005 to 5% by mass based on the total amount of the engine oil composition of the present invention.

Examples of antifoaming agents include silicone oils having a kinematic viscosity at 25 ° C. of 1,000 to 100,000 mm ² / s, alkenyl succinic acid derivatives, esters of polyhydroxy aliphatic alcohols and long chain fatty acids, methyl salicylates, o-Hydroxybenzyl alcohol.
When the antifoaming agent is contained in the engine oil composition of the present invention, the content is usually preferably 0.0001 to 0.01% by mass based on the total amount of the engine oil composition.

The viscosity index of the engine oil composition of the present invention is preferably 140 or more, more preferably 150 or more, and still more preferably 160 or more. By setting the viscosity index to 140 or more, sufficient fuel saving performance can be expected even at low temperatures. There is no particular limitation on the upper limit of the viscosity index.

Kinematic viscosity at 100 ° C. of the engine oil composition of the present invention is preferably at least 5.6 mm ² / s, more preferably at least 9.3 mm ² / s. Moreover, 12.5 mm < ² > / s or less is preferable and 11.5 mm < ² > / s or less is more preferable. By setting the kinematic viscosity at 100 ° C. to 12.5 mm ² / s or less, the fuel economy effect is not affected, and by setting it to 5.6 mm ² / s or more, a decrease in engine oil pressure is suppressed, and seizure occurs. Occurrence can be suppressed.

The high temperature and high shear viscosity measured at 100 ° C. with a shear rate of 1 × 10 ⁷ s ⁻¹ against the high temperature and high shear viscosity (a) of the engine oil composition measured at 100 ° C. with a shear rate of 1 × 10 ⁶ s ⁻¹ ( The ratio (b / a) of b) is preferably 0.85 or less, particularly preferably less than 0.80, so that a reduction in fuel economy can be suppressed. The lower limit of (b / a) is not particularly limited, but is usually about 0.77. Moreover, good fuel economy can be exhibited by keeping the viscosity at a shear rate of 1 × 10 ⁶ s ⁻¹ constant and reducing the viscosity at 1 × 10 ⁷ s ⁻¹ . Specifically, it is preferable that the former is 6.0 mPa · s or more, particularly 6.4 mPa · s or more, and the latter is 5.5 mPa · s or less, particularly 5.2 mPa · s or less.

The engine oil composition of the present invention can be applied to various engine engines, and is not particularly limited, but is preferably used for diesel engine engines.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
High temperature and high shear viscosity and abrasion resistance were measured and evaluated as shown below as indicators of fuel economy.
1. High temperature high shear viscosity (HTHS viscosity) of engine oil composition
High temperature and high shear viscosity at shear rates of 1 × 10 ⁶ s ⁻¹ and 1 × 10 ⁷ s ⁻¹ , which affect fuel economy, were measured as follows. The high temperature and high shear viscosity at a shear rate of 1 × 10 ⁶ s ⁻¹ was measured according to ASTM D4683-10, and the high temperature and high shear viscosity at a shear rate of 1 × 10 ⁷ s ⁻¹ was manufactured by PCS Instruments. Of USV viscometer. The measurement temperature is 100 ° C. for all.
In addition, good fuel economy can be exhibited by keeping the viscosity at a shear rate of 1 × 10 ⁶ s ⁻¹ constant and reducing the viscosity at 1 × 10 ⁷ s ⁻¹ . Specifically, it is preferable that the former is 6.0 mPa · s or more and the latter is 5.5 mPa · s or less.

2. Abrasion resistance of engine oil composition The wear resistance of the engine oil composition was evaluated using a shell four-ball test apparatus. The test method conformed to ASTM D2266. However, the test conditions are a rotation speed of 1800 rpm, a load of 492 N, an oil temperature of 120 ° C., and a test time of 1 minute.

Example 1
Using the components shown below, an engine oil composition according to Example 1 having a formulation composition (parts by mass) shown in Table 1 was prepared. About the engine oil composition of Example 1, the above 1. 1. high temperature high shear viscosity, and Abrasion resistance was evaluated. The evaluation results are shown in Table 1.
(1) Lubricating base oil: Base oil A; hydrocracking, catalytic dewaxing base oil. Details are shown in the margin of Table 1.
(2-1) Star polymer A-1: VM-A; SV261 (manufactured by Infinium); Mw 430,000, PSSI 25
(2-2) Polymer A-2: VM-B; polymethacrylate having nitrogen-containing group, Mw 260,000, PSSI 50, nitrogen content 0.1% by mass
(3-1) Component (B): Oleylamide (4) Metal-based detergent and antioxidant: A composition having the components shown in Table 2 (hereinafter referred to as package additive). In addition, content of each component shown in Table 2 is a mass part when the engine oil composition whole quantity of (1) is 100 mass parts.

Examples 2-5
The base oil and each additive were mix | blended with the compounding quantity shown in Table 1 and Table 2, and the engine oil composition of each Example was prepared. Each engine oil composition is the same as in Example 1 above. 1. high temperature high shear viscosity, and Abrasion resistance was evaluated. The results are shown in Table 1.
Here, components other than the above-described components are as follows.
(1) Lubricating base oil: Base oil B; hydrocracking, catalytic dewaxing base oil. Details are shown in the margin of Table 1.
(5) Pour point depressant (PPD): polymethacrylate, weight average molecular weight 55800

Comparative Examples 1-9
The base oil and each additive were mix | blended with the compounding quantity shown in Table 1 and Table 2, and the engine oil composition of each comparative example was prepared. Each engine oil composition is the same as in Example 1 above. 1. high temperature high shear viscosity, and Abrasion resistance was evaluated. The evaluation results are shown in Table 1.
In Comparative Examples 1 to 8, priority is given to fuel saving, and high temperature and high shear viscosity is set. The high temperature and high shear viscosity characteristics are almost the same as those of the examples. On the other hand, Comparative Example 9 is set with priority on wear resistance, and has a higher high-temperature and high-shear viscosity than the examples and other comparative examples. Particularly, the viscosity at 1 × 10 ⁷ s ⁻¹ is 5 Greatly exceeds 5 mPa · s.
Here, components other than the above-described components are as follows.
(2-3) Viscosity index improver other than component (A):
VM-C: polymethacrylate having nitrogen-containing groups, Mw 100,000, PSSI 5, nitrogen content 0.2% by mass
VM-D; polymethacrylate, Mw 430,000, PSSI 5
VM-E; polymethacrylate, Mw 450,000, PSSI 5
VM-F; polymethacrylate, Mw 380,000, PSSI 25
(3-2) Friction modifier other than component (B): oleylamine or glycerin monooleate (Adeka Cruve FM210 manufactured by Asahi Denka Kogyo Co., Ltd.) was used.

As is apparent from Table 1, the engine oil of each example using the components of star polymer A-1, polymer A-2, and (B) was significantly superior to the engine oils of comparative examples 1-9. Achieves both fuel saving and wear resistance.
That is, the engine oil composition of each example has a low high-temperature high-shear viscosity characteristic equivalent to that of Comparative Examples 1 to 8 and exhibits performance excellent in fuel saving performance, while being significantly better than Comparative Examples 1 to 8. It also has excellent wear resistance. The wear resistance of each of the examples is equivalent to that of Comparative Example 9 having high high temperature and high shear viscosity characteristics in which fuel saving performance cannot be expected. Therefore, both fuel saving performance and wear resistance are highly compatible. You can see that

Claims (6)

1. A lubricating base oil having a saturated content of 70% by mass or more and a viscosity index of 90 or more and 160 or less,
   (A) a star polymer A-1 and a polymer A-2 having a nitrogen-containing group having a weight average molecular weight of 200,000 or more and 400,000 or less,
   (B) An engine oil composition comprising at least one of an amide compound and an imide compound.
2. The engine oil composition according to claim 1, wherein the star polymer A-1 is a polymer having a core which is a polyalkenyl compound and 4 to 15 arms bonded to the core.
3. The engine oil composition according to claim 1 or 2, wherein the lubricating base oil has a kinematic viscosity at 100 ° C of 1.0 to 10.0 mm ² / s.
4. The engine oil composition has a kinematic viscosity at 100 ° C. of 5.6 mm ² / s to 12.5 mm ² / s, a shear rate of 1 × 10 ⁶ s ⁻¹ , and a high temperature high shear viscosity measured at 100 ° C. of 6 The engine oil composition according to any one of claims 1 to 3, wherein the engine oil composition is 0.0 mPa · s or more.
5. High temperature high shear viscosity measured at 100 ° C. with a shear rate of 1 × 10 ⁷ s ^{−1 with} respect to the high temperature high shear viscosity (a) measured at 100 ° C. with a shear rate of 1 × 10 ⁶ s ⁻¹ of the engine oil composition. The engine oil composition according to any one of claims 1 to 4, wherein the ratio (b / a) of (b) is 0.85 or less.
6. 6. The engine oil composition according to claim 1, wherein the engine oil composition is used for a diesel engine.