JP6420964B2 - Lubricating oil composition for internal combustion engines - Google Patents

Description

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

Various demands have been made for internal combustion engines used in automobiles, such as miniaturization and high output, fuel saving, exhaust gas regulations, and engine oils to satisfy these required performances. Various additives such as an ashless dispersant, an antioxidant, and a viscosity index improver are blended.
Conventionally, engine oils are required to improve performance from various viewpoints. For example, it may be required to suppress coking generated by carbonization of engine oil or to suppress copper elution from engine parts. In response to these requirements, for example, Patent Document 1 discloses that a hydrazide derivative having a specific structure is used as an additive in order to suppress copper elution. Patent Document 2 discloses that a specific molybdenum-based additive and a sulfurized fatty acid ester are used in combination in order to suppress coking.

Japanese Patent No. 4477337 Japanese Patent Laid-Open No. 2005-247995

By the way, the internal combustion engine has been improved in performance and output, and the operating conditions have become severe year by year. Therefore, it is necessary to further increase the oxidation stability of the engine oil, and there is an increasing demand for suppressing a decrease in base number over a long period of time.
In addition, for example, it is known that copper elution is likely to occur in city driving that repeats stop-and-go. Furthermore, in recent years, not only high speed areas but also low speed areas such as when driving in urban areas, turbo (supercharging) has been used to increase output, and it is expected that engines equipped with turbo mechanisms will increase in the future. Is done. However, it has been found that coking is likely to occur in an engine equipped with a turbo mechanism.
Therefore, it is necessary to suppress both coking and copper elution in a balanced manner in engine oil.

  However, the formulations disclosed in Patent Documents 1 and 2 are techniques for individually suppressing coking and copper elution, and effectively suppressing both coking and copper elution while suppressing a decrease in base number. Is difficult.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a lubricating oil composition for an internal combustion engine that suppresses a decrease in base number, occurrence of coking, and occurrence of copper elution in a balanced manner. It is to be.

As a result of intensive studies, the inventors of the present invention use a boron-containing succinimide and a poly (meth) acrylate in which the weight average molecular weight (Mw) and the ratio of the average carbon number of the alkyl group in the side chain are constant. The inventors have found that the above problems can be solved, and completed the present invention. The present invention provides the following (1) to (8).
(1) (A) lubricating base oil composed of mineral oil and / or synthetic oil;
(B) boron-containing alkenyl succinimide and / or boron-containing alkyl succinimide having a boron content converted value of 0.001 to 0.1% by mass based on the total amount of the composition;
When the weight average molecular weight is Mw and the average carbon number of the alkyl group measured by ¹³ C-NMR is X, Mw is 100,000 to 700,000, Mw / X is 30,000 or more, and 0 based on the total amount of the composition. A lubricating oil composition for an internal combustion engine comprising 1 to 30% by mass of (C) poly (meth) acrylate.
(2) The lubricating oil composition for an internal combustion engine according to (1), wherein Mw / X is 30,000 to 200,000.
(3) The lubricating oil composition for internal combustion engines according to the above (1) or (2), wherein (C) poly (meth) acrylate is non-dispersed.
(4) The lubricating oil composition for internal combustion engines according to any one of the above (1) to (3), wherein the viscosity index of the (A) lubricating base oil is 90 or more.
(5) The lubricating oil composition for internal combustion engines according to any one of (1) to (4), wherein the mineral oil has a paraffin content (% C _P ) of 60% or more by ring analysis.
(6) The internal combustion according to any one of (1) to (5) above, which contains at least one selected from (D) zinc dithiophosphate and (E) an alkali metal detergent or an alkaline earth metal detergent. Lubricating oil composition for engines.
(7) On the basis of the total amount of the composition, (D) zinc dithiophosphate is contained in an amount of 0.01 to 0.15% by mass in terms of phosphorus, and (E) an alkali metal detergent or alkaline earth metal detergent is metal The lubricating oil composition for internal combustion engines according to (6), which is contained in an amount of 0.1 to 0.3% by mass.
(8) The lubricating oil composition for internal combustion engines according to any one of (1) to (7), wherein the kinematic viscosity at 100 ° C. is 4 to 17 mm ² / s.
(9) (B) boron-containing alkenyl succinimide and (B) boron-containing alkenyl succinimide having a boron content converted value of 0.001 to 0.1% by mass based on the total amount of the composition in (A) lubricating base oil composed of mineral oil and / or synthetic oil Alternatively, a lubricating oil composition for an internal combustion engine is produced by blending boron-containing alkyl succinimide and 0.1 to 30% by mass of (C) poly (meth) acrylate based on the total amount of the composition,
(C) When poly (meth) acrylate has a weight average molecular weight of Mw and the average carbon number of the alkyl group measured by ¹³ C-NMR is X, Mw is 100,000 to 700,000 and Mw / X is 30,000. The manufacturing method of the lubricating oil composition for internal combustion engines which is the above.

  In the present invention, it is possible to provide a lubricating oil composition for an internal combustion engine that suppresses a decrease in base number, coking and copper elution in a balanced manner.

Hereinafter, preferred embodiments of the present invention will be described in detail.
[Lubricating oil composition for internal combustion engine]
The lubricating oil composition for internal combustion engines of the present invention (hereinafter sometimes simply referred to as “lubricating oil composition”) includes (A) a lubricating base oil, and (B) a boron-containing alkenyl succinimide and / or boron. Containing alkyl succinimide (hereinafter, also simply referred to as “boron-containing succinimide”) and (C) poly (meth) acrylate. Hereinafter, each component will be described in more detail.

[(A) Lubricating base oil]
(A) Lubricating oil base oil consists of mineral oil and / or synthetic oil, and can select and use arbitrary things from the mineral oil and synthetic oil conventionally used as a base oil of lubricating oil.
As mineral oil, for example, a lubricating oil fraction obtained by distillation under reduced pressure of atmospheric residual oil obtained by atmospheric distillation of crude oil can be desolvated, solvent extracted, hydrocracked, solvent dewaxed, catalytic dehydrated. Mineral oil refined by performing one or more treatments such as wax, hydrorefining, etc., and lubricating base oil produced by isomerizing GTL WAX, etc., among them hydrotreating Mineral oil treated with is preferred. Mineral oil treated by hydrorefining tends to improve the% C _P and viscosity index described below.

  Examples of synthetic oils include polyalphaolefins such as polybutene, α-olefin homopolymers and copolymers (for example, ethylene-α-olefin copolymers), such as polyol esters, dibasic acid esters, and phosphate esters. And various bases such as polyphenyl ether, polyglycol, alkylbenzene, alkylnaphthalene, and lubricating base oil produced by isomerizing GTL WAX. Of these synthetic oils, polyalphaolefins and esters are particularly preferred, and those combining these two are also suitably used as synthetic oils.

In the present invention, as the lubricating base oil, mineral oil may be used alone or in combination of two or more. In addition, one kind of synthetic oil may be used, or two or more kinds may be used in combination. Further, one or more mineral oils and one or more synthetic oils may be used in combination.
Further, (A) the lubricating base oil is a main component in the lubricating oil composition, and is usually 50% by mass or more, preferably 60 to 97% by mass, more preferably based on the total amount of the lubricating oil composition. Is contained in an amount of 65 to 95% by mass.

(A) No particular limitation is imposed on the viscosity of the lubricating base oil is a kinematic viscosity at 100 ° C. is preferably in the range of 1.0~20mm ² / s, a range of 1.5 to 15 mm ² / s It is more preferable that it is in the range of 2.0 to 13 mm ² / s. In the present invention, as described above, when the kinematic viscosity of the (A) lubricating base oil is set to a relatively low viscosity, fuel saving performance is easily realized. In addition, in this specification, kinematic viscosity is measured by the method described in the Example mentioned later.
The viscosity index of the (A) lubricating base oil is preferably 90 or more, more preferably 95 or more, and even more preferably 100 or more. The upper limit value of the viscosity index of the lubricating base oil is not particularly limited, but is preferably 170 or less, more preferably 160 or less, and even more preferably 150 or less.
When the viscosity index of the lubricating base oil is within the above range, the viscosity characteristics of the lubricating oil composition are easily improved. In the present specification, the viscosity index is measured by the method described in Examples described later.

The mineral oil preferably has a paraffin content (% C _P ) by ring analysis of 60% or more, and more preferably 65% or more. By making the paraffin content 60% or more, the oxidation stability of the base oil is improved, and the reduction of the base number and the occurrence of coking in the lubricating oil composition are suppressed. The measurement of the paraffin content (% C _P ) is as described later.

[(B) Boron-containing succinimide]
Examples of the boron-containing succinimide (B) used in the present invention include borides of alkenyl or alkyl succinic monoimide and alkenyl or alkyl succinic acid bisimide. Examples of the alkenyl or alkyl succinic acid monoimide include compounds represented by the following general formula (1). Moreover, as an alkenyl or alkyl succinic acid bisimide, the compound shown by following General formula (2) is mentioned, for example. In this invention, the cleanliness of a composition becomes favorable by mix | blending (B) component. Moreover, it becomes possible to suppress generation | occurrence | production of coking and copper elution by using with (C) component.

In the above formulas (1) and (2), R ¹ , R ³ and R ⁴ are an alkenyl group or an alkyl group, and the weight average molecular weights are preferably 500 to 3,000, more preferably 1, respectively. 000 to 3,000.
When the weight average molecular weight of R ¹ , R ³ and R ⁴ is 500 or more, the solubility in the base oil can be improved. Moreover, when it is 3,000 or less, it is expected that the effect obtained by the present compound is appropriately exhibited. R ³ and R ⁴ may be the same or different.
R ² , R ⁵ and R ⁶ are each an alkylene group having 2 to 5 carbon atoms, and R ⁵ and R ⁶ may be the same or different. m represents an integer of 1 to 10, and n represents 0 or an integer of 1 to 10. Here, m is preferably 2 to 5, more preferably 3 to 4. When m is 2 or more, it is expected that the effect obtained by the present compound is appropriately exhibited. When m is 5 or less, the solubility in the base oil is further improved.
In said formula (2), n becomes like this. Preferably it is 1-4, More preferably, it is 2-3. When n is 1 or more, it is expected that the effect obtained by the present compound is appropriately exhibited. When n is 4 or less, the solubility in the base oil is further improved.

  Examples of the alkenyl group include a polybutenyl group, a polyisobutenyl group, and an ethylene-propylene copolymer, and examples of the alkyl group include those obtained by hydrogenation thereof. Suitable alkenyl groups include polybutenyl or polyisobutenyl groups. As the polybutenyl group, a mixture of 1-butene and isobutene or a polymer obtained by polymerizing high-purity isobutene is preferably used. A representative example of a suitable alkyl group is a hydrogenated polybutenyl group or polyisobutenyl group.

(B) The boron-containing succinimide can be produced by a conventionally known method. For example, after reacting polyolefin with maleic anhydride to make alkenyl succinic anhydride, polyamine and boron oxide, boron halide, boron halide, boric acid, boric anhydride, boric acid ester, boric acid ammonium salt, etc. It is obtained by reacting with an intermediate obtained by reacting a compound and imidizing. Monoimides or bisimides can be made by changing the ratio of alkenyl succinic anhydride or alkyl succinic anhydride to polyamine.
Further, (B) the boron-containing succinimide may be obtained by treating boron-free alkenyl or alkyl succinic monoimide or alkenyl or alkyl succinic acid bisimide with the boron compound.

As the olefin monomer forming the above-mentioned polyolefin, one or two or more kinds of α-olefins having 2 to 8 carbon atoms can be mixed and used, but a mixture of isobutene and 1-butene is preferably used. be able to.
On the other hand, polyamines include single diamines such as ethylenediamine, propylenediamine, butylenediamine, pentylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, di (methylethylene) triamine, dibutylenetriamine, triethylene. And polyalkylene polyamines such as butylenetetramine and pentapentylenehexamine, and piperazine derivatives such as aminoethylpiperazine.

  The said (B) component is contained 0.001-0.1 mass% in the boron amount conversion value of composition whole quantity reference | standard. When it is less than 0.001% by mass, it becomes difficult to suppress the occurrence of coking and copper elution. Moreover, when it exceeds 0.1 mass%, it will become difficult to exhibit the effect corresponding to the compounding quantity, such as producing precipitation. From these viewpoints, the content of the component (B) is a converted value of boron based on the total amount of the composition, more preferably 0.005 to 0.08% by mass, and still more preferably 0.010 to 0.0. 06% by mass.

Further, the mass ratio (B / N ratio) of boron and nitrogen in the component (B) is preferably 0.8 or more, preferably 1.0 or more, and preferably 1.1 or more. The upper limit of the B / N ratio is not particularly limited, but is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.3 or less. By making B / N ratio into the said range, it becomes easy to exhibit the effect acquired by this compound appropriately.
In addition, although content of (B) component should just be the quantity which the said boron amount conversion value becomes in the said range, it is about 0.1-10 mass% normally on the basis of the composition whole quantity, Preferably it is 0. 0.5 to 5% by mass, more preferably 1 to 4% by mass.

[(C) Poly (meth) acrylate]
The (C) poly (meth) acrylate contained in the lubricating oil composition of the present invention has a weight average molecular weight of Mw and an average carbon number of alkyl groups measured by ¹³ C-NMR of X, Mw is 100,000. A poly (meth) acrylate having a Mw / X of 30,000 or more while being ˜700,000.
In addition, although the measuring method of Mw and X is as the Example mentioned later, an alkyl group means all the alkyl groups which exist in poly (meth) acrylate, for example in General formula (3) mentioned later, R ⁷ and R ⁸ are meant, and when an alkyl group is bonded to COO— of (meth) acrylate via another substituent, such an alkyl group is also included. The average carbon number means an arithmetic average value.

  In this invention, in addition to the said (B) component, (C) component contains, The elution of copper to a lubricating oil composition and generation | occurrence | production of coking are suppressed with sufficient balance. The principle is not clear, but is estimated as follows. Poly (meth) acrylate (hereinafter also referred to as “PMA”) is estimated to partly form a complex with copper due to decomposition or the like, and may elute copper from alloys of parts such as engine bearings. Yes. When PMA has a structure in which the PMAs are easily entangled with each other, the amount of PMA attached to the engine metal surface is reduced, and as a result, elution of copper is suppressed. Moreover, when PMA is decomposed, the reactivity increases, and this causes a tendency to cause coking and copper elution. In the present invention, the action of the component (B) promotes the ease of entanglement of PMA and suppresses the decomposition of PMA, thereby balancing the elution of copper into the lubricating oil composition and the occurrence of coking. It is suppressed.

In the present invention, the balance of the size of the alkyl groups in the side chain of Mw and PMA is important. When there are a large number of small alkyl groups in the side chain, PMA tends to be entangled even at a relatively low Mw, When the group has a certain proportion or more in the side chain, it is presumed that PMA is difficult to be entangled even with a relatively high Mw. Furthermore, when a large alkyl group is present in the side chain at a certain ratio or higher and the Mw is relatively high, it is estimated that PMA is likely to be decomposed although PMA is less likely to be entangled. Therefore, when Mw / X is less than 30,000, adhesion of PMA to the engine metal surface cannot be sufficiently reduced, and further, PMA is easily decomposed, and it becomes difficult to suppress copper elution and coking.
In addition, when Mw is within a certain range, the reactivity of PMA becomes small even when there are many side chain alkyl groups having a certain size, while when Mw exceeds 700,000, the side chain is small. Even if there are a large number of alkyl groups, the reactivity of PMA is presumed to increase, and coking and copper elution are likely to occur. In addition, when the molecular weight is less than 100,000, it is estimated that even if there are many small alkyl groups in the side chain, it is difficult to get entangled, and copper elution cannot be sufficiently suppressed.
Moreover, oxidation stability increases and it can suppress the fall of a base number by containing (C) component which has Mw and Mw / X in a fixed range.

In order to suppress copper elution and coking in a well-balanced manner, Mw / X is preferably 30,000 to 200,000, more preferably 30,000 to 130,000, and suppresses copper elution more appropriately. From a viewpoint, it is more preferable that it is 30,000-100,000.
The weight average molecular weight (Mw) is preferably 100,000 to 700,000, more preferably 150,000 to 600,000, and further preferably 180,000 to 550,000.

(C) The poly (meth) acrylate is preferably a polymer of a polymerizable monomer containing a (meth) acrylate monomer represented by the following general formula (3).
In the general formula (3), R ⁷ represents hydrogen or a methyl group, and R ⁸ represents a linear or branched alkyl group having 1 to 200 carbon atoms. R ⁸ is preferably an alkyl group having 1 to 40 carbon atoms, more preferably an alkyl group having 1 to 28 carbon atoms, and still more preferably an alkyl group having 1 to 25 carbon atoms.
In the general formula (3), R ⁸ is specifically methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl. Group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, heicosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, hexacosyl group, heptacosyl group, octacosyl group Nonacosyl group, triacontyl group, hentriacontyl group, dotriacontyl group, tritriacontyl group, tetracontyl group, pentatriacontyl group, hexatricontyl group, octatriacontyl group, tetracontyl group, etc. Whether chain or branched There.

In the present invention, the component (C) is preferably non-dispersed. Specific examples of the non-dispersed poly (meth) acrylate include a single homopolymer of the monomer represented by the general formula (3) or a poly (meth) acrylate obtained by copolymerization of two or more types. It is done.
However, (C) poly (meth) acrylate may be dispersed poly (meth) acrylate. Examples of the dispersion type poly (meth) acrylate include those obtained by copolymerizing a monomer represented by the general formula (3) and one or more monomers selected from the following general formulas (4) and (5).

In General Formula (4), R ⁹ represents a hydrogen atom or a methyl group, R ¹⁰ represents an alkylene group having ¹ to 28 carbon atoms, E ¹ represents ¹ to 2 nitrogen atoms and 0 to 2 oxygen atoms. An amine residue or a heterocyclic residue to be contained is shown, and a represents 0 or 1.

In the general formula (5), R ¹¹ represents a hydrogen atom or a methyl group, and E ² represents an amine residue or a heterocyclic residue containing 1 to 2 nitrogen atoms and 0 to 2 oxygen atoms.

Specific examples of the group represented by E ¹ and E ² include a dimethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, an anilino group, a toluidino group, a xylidino group, an acetylamino group, and a 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 and the like.

Preferable examples of the monomer represented by the general formulas (4) and (5) include dimethylaminomethyl methacrylate, diethylaminomethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-methyl-5-vinylpyridine, Examples thereof include morpholinomethyl methacrylate, morpholinoethyl methacrylate, N-vinylpyrrolidone and a mixture thereof.
There is no particular limitation on the copolymerization molar ratio of the copolymer of the monomer (M1) represented by the general formula (3) and the monomer (M2) represented by the general formula (4) and / or (5), M1: M2 is preferably about 99: 1 to 80:20, more preferably 98: 2 to 85:15, and still more preferably 95: 5 to 90:10.

In the component (C) of the present invention, the monomer represented by the general formula (3) is preferably 70% by mass in the total monomer components constituting the component (C), and 85% by mass or more. More preferably, it is 90 mass% or more.
Moreover, (C) component may contain the structural unit derived from monomers other than the said General Formula (3)-(5) in the range which is not contrary to the objective of this invention. Usually, such a monomer component is about 10% by mass or less based on the total monomer components.

  More specifically, the component (C) includes at least an alkyl (meth) acrylate monomer having an alkyl group having 1 to 4 carbon atoms and an alkyl (meth) acrylate monomer having an alkyl group having 12 to 40 carbon atoms. Copolymerized or alkyl (meth) acrylate monomer having 1 to 4 carbon atoms in the alkyl group, alkyl (meth) acrylate monomer having 5 to 11 carbon atoms in the alkyl group, and 12 to 12 carbon atoms in the alkyl group Examples include those obtained by copolymerizing at least 40 alkyl (meth) acrylate monomers. Among these, an alkyl (meth) acrylate monomer having an alkyl group having 1 to 4 carbon atoms and an alkyl (meth) acrylate monomer having an alkyl group having 12 to 40 carbon atoms are preferably copolymerized at least. More preferably, a copolymer of at least a methyl (meth) acrylate monomer and an alkyl (meth) acrylate monomer having an alkyl group having 16 to 25 carbon atoms is used.

  (C) Content of poly (meth) acrylate is 0.1-30 mass% on the composition whole quantity basis. If it is less than 0.1% by mass, it will be difficult to balance the reduction in base number, the occurrence of coking and the elution of copper. When it exceeds 30 mass%, it will become difficult to exhibit the effect corresponding to the content. Content of the said (C) component becomes like this. Preferably it is 0.3-25 mass%, More preferably, it is 0.5-10 mass%. In addition, content of (C) component means content of the resin part.

[(D) Zinc dithiophosphate]
The lubricating oil composition of the present invention may contain (D) zinc dithiophosphate. (D) By containing zinc dithiophosphate, it is possible to improve oxidation resistance while improving wear resistance. Examples of zinc dithiophosphate include compounds represented by the following general formula (6).

R < ¹² >, R < ¹³ >, R < ¹⁴ > and R < ¹⁵ > in General formula (6) show a C1-C24 hydrocarbon group each independently. Examples of these hydrocarbon groups include linear or branched alkyl groups having 1 to 24 carbon atoms, linear or branched alkenyl groups having 3 to 24 carbon atoms, and cycloalkyl groups having 5 to 13 carbon atoms. Or a linear or branched alkylcycloalkyl group, an aryl group having 6 to 18 carbon atoms, or a linear or branched alkylaryl group, and an arylalkyl group having 7 to 19 carbon atoms. Of these, alkyl groups are preferred.
Specifically, zinc dialkyldithiophosphate is preferable as zinc dithiophosphate, and secondary zinc dialkyldithiophosphate is particularly preferable.
The content of zinc dithiophosphate is more preferably 0.005 to 0.30% by mass, and further preferably 0.01 to 0.15% by mass in terms of phosphorus with respect to the total amount of the composition. . By setting it within the above range, the antiwear property and oxidation stability of the lubricating oil composition can be improved without affecting cleanliness and coking resistance.

[(E) Metal-based detergent]
The lubricating oil composition may further contain (E) a metal detergent comprising an alkali metal detergent or an alkaline earth metal detergent. (E) By containing a metal-type detergent, it becomes easy to suppress a base number fall and generation | occurrence | production of coking and copper elution, improving a cleanliness | purity.
Specific examples include one or more metal detergents selected from alkali metal sulfonates or alkaline earth metal sulfonates, alkali metal phenates or alkaline earth metal phenates, alkali metal salicylates, alkaline earth metal salicylates, and the like. It is done. Examples of the alkali metal include sodium and potassium, and examples of the alkaline earth metal include magnesium and calcium. The alkali metal sodium, the alkaline earth metal magnesium and calcium are preferably used, and calcium is more preferable.

These alkali metal detergents or alkaline earth metal detergents may be neutral, basic, or overbased, but are preferably basic or overbased, and their total base number Is preferably 10 to 500 mgKOH / g, more preferably 150 to 450 mgKOH / g. The total base number is measured in accordance with the perchloric acid method of JIS K-2501.
(E) The metal detergent may be, for example, 150 to 450 mgKOH / g alone, but with an alkali metal detergent or alkaline earth metal detergent having a total base number of 150 to 450 mgKOH / g 5-100 mg KOH / g alkali metal detergent or alkaline earth metal detergent may be used in combination.
(E) The content of the metal-based detergent is preferably 0.05 to 0.5% by mass and 0.1 to 0.3% by mass in terms of the metal amount with respect to the total amount of the composition. Is more preferable. By containing more than these lower limits, it becomes easier to suppress the base number decrease, coking and copper elution. Moreover, it becomes possible to exhibit the effect corresponding to content by setting it as below an upper limit.
The lubricating oil composition contains 0.01 to 0.15% by mass of (D) zinc dithiophosphate in terms of phosphorus based on the total amount of the composition, and (E) 0.1 wt. It is more preferable to contain -0.3 mass%.

[Other ingredients]
The lubricating oil composition may contain boron-free succinimide in addition to (B) boron-containing succinimide. The boron-free succinimide is an alkenyl succinimide and / or an alkyl succinimide that does not contain boron. Examples of alkenyl succinimide and / or alkyl succinimide include alkenyl or alkyl succinic acid monoimide or alkenyl or alkyl succinic acid bisimide.
The boron-free succinimide is not particularly limited, but is usually about 0.1 to 10% by mass, preferably about 0.5 to 5% by mass based on the total amount of the composition.

The lubricating oil composition may further contain an antioxidant. Antioxidants include amine-based antioxidants, phenol-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, molybdenum-amine complex-based antioxidants, and among these, amine-based antioxidants Agents and phenolic antioxidants are preferred. These can be arbitrarily selected from known antioxidants conventionally used as antioxidants for lubricating oils.
Examples of amine-based antioxidants include diphenylamines and diphenylamines such as dialkyldiphenylamines having an alkyl group having 3 to 20 carbon atoms; naphthylamines such as α-naphthylamine and alkyl-substituted phenyl-α-naphthylamines having 3 to 20 carbon atoms. The one of the system is mentioned.
Examples of the phenolic antioxidant include 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, and octadecyl-3- (3,5 Monophenols such as -di-tert-butyl-4-hydroxyphenyl) propionate; 4,4'-methylenebis (2,6-di-tert-butylphenol), 2,2'-methylenebis (4-ethyl- 6-tert-butylphenol) and the like.
Examples of the sulfur-based antioxidant include dilauryl-3,3′-thiodipropionate, and examples of the phosphorus-based antioxidant include phosphite.
As the molybdenum amine complex-based antioxidant, a hexavalent molybdenum compound, specifically, a product obtained by reacting molybdenum trioxide and / or molybdic acid with an amine compound, for example, described in JP-A-2003-252887. The compound obtained by the production method can be used.
These antioxidants can be contained alone or in any combination of two or more kinds, but it is usually preferable to use two or more kinds in combination.
The content of the antioxidant is preferably about 0.01 to 10% by mass, and preferably about 0.1 to 5% by mass based on the total amount of the composition.

The lubricating oil composition may further contain at least one additive selected from friction modifiers and antiwear agents other than those described above.
Specifically, sulfur compounds such as sulfurized olefins, dialkyl polysulfides, diarylalkyl polysulfides, diaryl polysulfides, phosphoric acid esters, thiophosphoric acid esters, phosphorous acid esters, alkyl hydrogen phosphites, phosphoric acid ester amine salts, phosphorous acid compounds. Phosphorus compounds such as acid ester amine salts, zinc dithiocarbamate (ZnDTC), sulfurized oxymolybdenum organophosphorodithioate (MoDTP), organometallic compounds such as sulfurized oxymolybdenum dithiocarbamate (MoDTC), amine compounds, fatty acid esters, Examples include ashless friction modifiers such as fatty acid amides, fatty acids, aliphatic alcohols, aliphatic ethers, urea compounds, and hydrazide compounds. These may be used individually by 1 type and may be used in combination of 2 or more type.
Among these, it is preferable to use sulfurized oxymolybdenum dithiocarbamate from the viewpoint of fuel economy. The content of these friction modifiers and antiwear agents is preferably about 0.01 to 8% by mass, more preferably 0.1 to 5% by mass based on the total amount of the composition.
The lubricating oil composition may further contain components such as a pour point depressant, a metal deactivator, a pour point depressant, and an antifoaming agent.

The kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is not particularly limited, but is usually about ^{2 to} 25 mm ² / s, preferably 3 to 22 mm ² / s, more preferably 4 to 17 mm ² / s. is there. Thus, it becomes easy to improve fuel-saving property by making a composition into low viscosity. The viscosity index of the lubricating oil composition is preferably 150 or more, more preferably about 170 to 300, and further preferably about 180 to 250.

  The lubricating oil composition of the present invention is a lubricating oil composition for an internal combustion engine used for various internal combustion engines such as a four-wheeled vehicle and a two-wheeled vehicle. When urban driving that repeats stop-and-go in an automobile is performed with, for example, an engine equipped with a turbo mechanism capable of increasing output, coking and copper elution are likely to occur in the lubricating oil composition used in the internal combustion engine. The lubricating oil composition can suppress coking and copper elution in a balanced manner.

[Method for producing lubricating oil composition]
The method for producing a lubricating oil composition of the present invention is a method for producing a lubricating oil composition by blending the components (B) and (C) with the (A) lubricating base oil. Moreover, in the manufacturing method of the lubricating oil composition of the present invention, in addition to the components (B) and (C), the above components (D) and (E) and other components may be added to the lubricating base oil. Good.
(A) The amount of the lubricating base oil, and the amount (blending amount) in which the components (B) to (E) and other components are blended may be the same as the content of each component described above. Further, since the properties of the lubricating oil composition and details of each component are as described above, description thereof is omitted.
In this manufacturing method, each component may be blended with the base oil by any method, and the method is not limited.
In addition, (B) and (C) component, Furthermore, (D) and (E) component and the lubricating oil composition formed by further mix | blending one or more components selected from these other components as needed Usually contains these blends, but in some cases, at least a part of the blended additives may react to form another compound.

  EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited at all by these examples.

In this specification, the measurement of each physical property and the evaluation of the lubricating oil composition are determined according to the following procedure.
(1) Kinematic viscosity It is a value measured using a glass capillary viscometer according to JIS K2283.
(2) Viscosity index It is a value measured according to JIS K 2283.
(3) NOACK evaporation amount This is a value measured according to the method prescribed in JPI-5S-41.
(4) Paraffin content by ring analysis (% C _P )
The ratio (percentage) of the paraffin calculated by the ring analysis ndM method is shown and measured according to ASTM D-3238.
(5) Base number Measured by the perchloric acid method in accordance with JIS K2501.
(6) Average carbon number of poly (meth) acrylate (X)
^It was calculated from the chemical shift and integrated value of ¹³ C-NMR. Specifically, first, the ratio of each alkyl group was determined from the total integrated value of the alkyl group and the integrated value of each alkyl group, and calculated according to the following formula.
Average carbon number X = (total carbon number of each alkyl group × ratio of each alkyl group) The measurement conditions of ¹³ C-NMR are as follows.
Equipment: ECX-400P (manufactured by JEOL Ltd.) Solvent: CDCl3
Resonance frequency: 100 MHz Measurement mode Decoupling method with gate Integration number: 2000-5000 Pulse delay time: 25 s
Pulse width: 9.25us x-angle: 90 °
(7) Weight average molecular weight (Mw) of poly (meth) acrylate
The weight average molecular weight (Mw) is measured under the following conditions, and is a value obtained using polystyrene as a calibration curve. Specifically, it is measured under the following conditions.
Instrument: Agilent 1260 HPLC Column: Shodex LF404 x 2 Solvent: Chloroform Temperature: 35 ° C
Sample concentration: 0.05% Calibration curve: Polystyrene detector Differential refraction detector (8) Total base number and base number reduction rate after degradation by ISOT In ISOT test (165.5 ° C.) according to JIS K 2514, test oil Copper pieces and iron pieces were put into the (lubricating oil composition) as a catalyst to forcibly deteriorate the test oil, and the total base number (perchloric acid method) after 96 hours was measured. In addition, the decrease rate of the total base number of the test oil due to deterioration with respect to the total base number of the new oil was calculated. The lower the decrease rate, the higher the base number maintenance property, indicating a longer drain oil that can be used for a longer period of time.
(9) Copper elution amount after deterioration by ISOT The copper elution amount of the test oil after deterioration by the ISOT test was measured.
(10) Panel coking test
In accordance with Federal test method 791B / 3462, the panel temperature was 300 ° C. and the oil temperature was 100 ° C., and the test was conducted for 3 hours with a cycle of a splash time of 15 seconds and a stop time of 45 seconds. After the test was completed, the caulk adhered to the panel was evaluated.

[Examples 1 to 9, Comparative Examples 1 to 4]
As shown in Table 1, (A) lubricating base oil, (B) to (E) components, and other components are blended, and (A) lubricating base oil and each example containing these components. The lubricating oil composition of Comparative Example was prepared, the lubricating oil composition was evaluated, and the results are shown in Table 1.

* Each component in Table 1 represents the following.
(A) Lubricating base oil Lubricating base oil (A1): GroupIII 150N hydrorefined base oil, 100 ° C kinematic viscosity 6.4mm ² / s, viscosity index 131, NOACK evaporation (250 ° C, 1 hour) 7.0% by mass , ndM ring analysis% Cp.79.1%
Lubricating base oil (A2): GroupIII 100N hydrorefined base oil, 100 ° C kinematic viscosity 4.1mm ² / s, viscosity index 134, NOACK evaporation (250 ° C, 1 hour) 12.9% by mass, ndM ring analysis% Cp. 87.7%
Lubricating base oil (A3): Group IV polyalphaolefin, 100 ° C kinematic viscosity 3.7mm ² / s, viscosity index 117, NOACK evaporation (250 ° C, 1 hour) 15.6% by mass
Lubricating base oil (A4): Group IV ester base oil, 100 ° C kinematic viscosity 4.3mm ² / s, viscosity index 139, NOACK evaporation (250 ° C, 1 hour) 2.6% by mass
(In Example 8, the lubricating base oil is a mixture of the lubricating base oil (A3) and the lubricating base oil (A4), and the 100 ° C. kinematic viscosity of the mixed base oil is 4.3 mm. ² / s, viscosity index 130.)
(B) Boron-containing succinimide Boron-containing succinimide (B1): Boronated polybutenyl succinimide, boron content 1.3 mass%, nitrogen content 1.2 mass%, weight average molecular weight of polybutenyl group 1, 800, B / N ratio 1.1
(C) poly (meth) acrylate poly (meth) acrylate (C1): polyalkyl (meth) acrylate, weight average molecular weight 200,000, average carbon number (X): 4.6, resin content: 28% by mass
Poly (meth) acrylate (C2): polyalkyl (meth) acrylate, weight average molecular weight 510,000, average carbon number (X): 5.7, resin content: 19% by mass
Poly (meth) acrylate (C3): polyalkyl (meth) acrylate, weight average molecular weight 440,000, average carbon number (X): 5.8, resin content: 16% by mass
Poly (meth) acrylate (C4): polyalkyl (meth) acrylate, weight average molecular weight 370,000, average carbon number (X): 5.6, resin content: 26% by mass
Poly (meth) acrylate (C5): polyalkyl (meth) acrylate, weight average molecular weight 430,000, average carbon number (X): 6.3, resin content: 42% by mass
Poly (meth) acrylate (C6): polyalkyl (meth) acrylate, weight average molecular weight 44,000, average carbon number (X): 7.3, resin content: 53% by mass
Poly (meth) acrylate (C7): polyalkyl (meth) acrylate, weight average molecular weight 90,000, average carbon number (X): 8.1, resin content: 46% by mass
Poly (meth) acrylate (C8): polyalkyl (meth) acrylate, weight average molecular weight 210,000, average carbon number (X): 9.4, resin content: 44% by mass
(D) zinc dithiophosphate ZnDTP (D1): zinc dialkyldithiophosphate, zinc content 9.0% by mass, phosphorus content 8.2% by mass, sulfur content 17.1% by mass, alkyl group; secondary butyl group and secondary hexyl Mixture of base (E) Metal-based detergent Metal-based detergent (E1): Basic calcium phenate, total base number (perchloric acid method) 255 mgKOH / g, calcium content 9.3 mass%, sulfur content 3.0 mass%
Metal detergent (E2): basic calcium salicylate, total base number (perchloric acid method) 225 mgKOH / g, calcium content 7.8 mass%, sulfur content 0.2 mass%
Metal detergent (E3): basic calcium sulfonate, total base number (perchloric acid method) 300mgKOH / g, calcium content 11.6 mass%, sulfur content 1.49 mass%
-Other components Boron-free succinimide: Polybutenyl succinic acid bisimide, polybutenyl group number average molecular weight 2300, nitrogen content 1.0 mass%, chlorine content 0.01 mass% or less Amine-based antioxidant: dialkyldiphenylamine, nitrogen Content 4.62% by mass
Phenol antioxidant: octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate MoDTC: sulfurized oxymolybdenum dithiocarbamate, molybdenum content 10.0% by mass, sulfur content 11.5% by mass

As is clear from the results in Table 1, the lubricating oil compositions of Examples 1 to 9 contain a boron-containing succinimide and a polyalkyl (meth) acrylate having specific Mw and Mw / X. While suppressing a decrease in base number in the deterioration test, it was possible to suppress the occurrence of coking and copper elution.
On the other hand, in Comparative Examples 1 to 3, since the Mw and Mw / X of the polyalkyl (meth) acrylate were not within the predetermined range, the occurrence of coking and copper elution could not be sufficiently suppressed. Further, since the lubricating oil composition of Comparative Example 4 does not contain boron-containing succinimide, coking and copper elution are sufficiently generated even when Mw and Mw / X of polyalkyl (meth) acrylate are within a predetermined range. Could not be suppressed.

  The lubricating oil composition for an internal combustion engine of the present invention can suppress a decrease in base number, the occurrence of coking, and the occurrence of copper elution in a well-balanced manner, and can be suitably used, for example, for an internal combustion engine for automobiles.

Claims (10)

(A) a lubricating base oil composed of mineral oil and / or synthetic oil;
(B) boron-containing alkenyl succinimide and / or boron-containing alkyl succinimide having a boron content converted value of 0.001 to 0.1% by mass based on the total amount of the composition;
A lubricating oil composition for an internal combustion engine comprising 0.1 to 30% by mass of (C) poly (meth) acrylate based on the total amount of the composition,
(C) poly (meth) acrylate, a weight average molecular weight measured by ^Mw, 13 C-NMR, the average number of carbon atoms of the A alkyl groups calculated from the following calculation formula when the X, Mw 180,000 600,000, Mw / X is from 30,000 to 100,000, monomers, non-distributed, which is a (C) more than 90 wt% in total monomer components constituting the component represented by the following general formula (3) poly (meth) acrylates bets, lubricating oil compositions for internal combustion engines.
Average carbon number X = (carbon number of each alkyl group × ratio of each alkyl group) total
(In the calculation formula, the number of carbon atoms of each alkyl group is specified from a chemical shift measured by ¹³ C-NMR. The proportion of each alkyl group is an alkyl group measured by ¹³ C-NMR. Calculated from the sum of the integral values of and the integral value of each alkyl group.)

(In General Formula (3), R ⁷ represents hydrogen or a methyl group, and R ⁸ represents a linear or branched alkyl group having 1 to 200 carbon atoms.) 2. The lubricating oil composition for an internal combustion engine according to claim 1, wherein in the general formula (3), R ⁸ is a linear or branched alkyl group having 1 to 40 carbon atoms . (C) The poly (meth) acrylate is a non-dispersed poly (meth) acrylate which is a copolymer of two or more monomers represented by the general formula (3), and is in the general formula (3) , An alkyl (meth) acrylate monomer having 1 to 4 carbon atoms in the alkyl group of R ⁷ and R ⁸ and an alkyl (meth) acrylate monomer having 12 to 40 carbon atoms in the alkyl group of R ⁷ and R ^8. The lubricating oil composition for an internal combustion engine according to claim 1 or 2 , which is a copolymer obtained by copolymerization .   (A) The lubricating oil composition for internal combustion engines according to any one of claims 1 to 3, wherein the lubricating base oil has a viscosity index of 90 or more. The lubricating oil composition for an internal combustion engine according to any one of claims 1 to 4, wherein the mineral oil has a paraffin content (% C _P ) by ring analysis of 60% or more.   The lubricating oil composition for an internal combustion engine according to any one of claims 1 to 5, comprising at least one selected from (D) zinc dithiophosphate and (E) an alkali metal detergent or an alkaline earth metal detergent. .   On the basis of the total amount of the composition, (D) containing 0.01 to 0.15% by mass of zinc dithiophosphate in terms of phosphorus, (E) alkali metal or alkaline earth metal detergent in terms of metal The lubricating oil composition for an internal combustion engine according to claim 6, containing 0.1 to 0.3% by mass. The lubricating oil composition for an internal combustion engine according to any one of claims 1 to 7, which has a kinematic viscosity at 100 ° C of 4 to 17 mm ² / s. Furthermore, the lubricating oil composition for internal combustion engines in any one of Claims 1-8 containing the metal type detergent whose (E) total base number is 150-450 mgKOH / g. (B) Boron-containing alkenyl succinimide and / or boron containing (A) lubricating base oil composed of mineral oil and / or synthetic oil, based on the total amount of the composition based on 0.001 to 0.1% by mass of boron. A lubricating oil composition for an internal combustion engine is produced by blending alkyl succinimide and 0.1 to 30% by mass of (C) poly (meth) acrylate based on the total amount of the composition,
(C) poly (meth) acrylate, a weight average molecular weight measured by ^Mw, 13 C-NMR, the average number of carbon atoms of the A alkyl groups calculated from the following calculation formula when the X, Mw 180,000 600,000, Mw / X is from 30,000 to 100,000, monomers, non-distributed, which is a (C) more than 90 wt% in total monomer components constituting the component represented by the following general formula (3) The manufacturing method of the lubricating oil composition for internal combustion engines which is poly (meth) acrylate .
Average carbon number X = (carbon number of each alkyl group × ratio of each alkyl group) total
(In the calculation formula, the number of carbon atoms of each alkyl group is specified from a chemical shift measured by ¹³ C-NMR. The proportion of each alkyl group is an alkyl group measured by ¹³ C-NMR. Calculated from the sum of the integral values of and the integral value of each alkyl group.)

(In General Formula (3), R ⁷ represents hydrogen or a methyl group, and R ⁸ represents a linear or branched alkyl group having 1 to 200 carbon atoms.)