JP2013147531A - Viscosity index improvement agent for lubricating oil, additive composition for lubricating oil, and lubricating oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a viscosity index improvement agent for a lubricating oil, which has a function to improve soot dispersibility of the lubricating oil, and to provide a lubricating oil composition excellent in the soot dispersibility.SOLUTION: The viscosity index improvement agent for a lubricating oil is composed of an ethylene/α-olefin/cyclic olefin copolymer (A) which includes: 18 to 85.5 mol% of a structural unit derived from ethylene; 9 to 76 mol% of a structural unit derived from at least one kind of α-olefin selected from 3-20C α-olefins; and 5-10 mol% of a structural unit derived from a specific cyclic olefin; wherein no melting peak measured by a differential scanning calorimeter (DSC) exists, and the glass transition temperature Tg is -12°C or lower.

Description

  The present invention relates to a viscosity index improver for lubricating oil, an additive composition for lubricating oil, and a lubricating oil composition.

  Petroleum products generally have a so-called viscosity temperature dependency in which the viscosity changes greatly when the temperature changes. For example, in a lubricating oil composition used for an automobile or the like, it is preferable that the temperature dependence of the viscosity is small. Therefore, in order to reduce the temperature dependency of the viscosity, a certain kind of polymer that is soluble in the lubricating oil base is used as the lubricating oil viscosity index improver.

  Conventionally, ethylene / α-olefin copolymers have been widely used as such viscosity index improvers for lubricating oils, and various improvements have been made to further improve the performance balance of lubricating oils (for example, patents). Reference 1, Patent Document 2, and Patent Document 3).

  On the other hand, the lubricating oil composition used for automobiles, etc., when used for a long time, with the deterioration of the lubricating oil, internal combustion engine, such as increased dirt and wear of the lubrication site due to the generation of sludge, increased power loss, etc. It is known to induce various problems to the driving system site. In particular, in the case of diesel engine oil, high dispersion performance is required due to the presence of soot. For this reason, various additives for dispersing sludge and soot in the lubricating oil have been proposed (see, for example, Patent Document 4, Patent Document 5, and Patent Document 6).

  However, lubricating oil compositions containing these sludge and soot-dispersing additives are not sufficient in terms of low-temperature characteristics and fuel efficiency. There is a need for a well-balanced viscosity index improver for lubricating oils that can also improve fuel economy.

International Publication No. 00/034420 International Publication No. 06/028169 JP 2002-348585 A JP-A-1-149899 JP 2001-107074 A JP 2007-197509 A

  The present invention includes a soot dispersibility, a low temperature characteristic and a fuel oil viscosity index improver capable of improving fuel economy, and a soot dispersibility containing the viscosity index improver for the lubricating oil, a low temperature characteristic, It is an object to provide an additive composition for lubricating oil that can be used to obtain a lubricating oil composition that is excellent in fuel economy, and a lubricating oil composition that is excellent in soot dispersibility, low temperature characteristics, and fuel economy. .

  As a result of diligent research, the present inventors have found that when a specific ethylene / α-olefin / cycloolefin copolymer is used as a viscosity index improver for lubricating oil, sludge, soot dispersibility, and low temperature characteristics of the resulting lubricating oil composition are obtained. The present invention has been completed by finding that the fuel efficiency is excellent.

That is, the present invention
[1]
18 to 85.5 mol% of structural units derived from ethylene, 9 to 76 mol% of structural units derived from at least one α-olefin selected from α-olefins having 3 to 20 carbon atoms, and the following general formula (I Ethylene / α having a glass transition temperature Tg of −12 ° C. or less without a melting peak measured by a differential scanning calorimeter (DSC). -Viscosity index improver for lubricating oil comprising olefin / cyclic olefin copolymer (A).
Formula (I)

（式中、Ｒ₁〜Ｒ₆は互いに同一でも異なっていてもよく、水素原子、ハロゲン原子、メチル基、エチル基、あるいはＲ₁とＲ₂、Ｒ₃とＲ₄、Ｒ₅とＲ₆でそれぞれ炭素数１〜２のアルキリデン基を形成していてもよい。）
であり、好ましくは以下のいずれかである。

(In the formula, R _{1 to} R ₆ may be the same as or different from each other, and may be a hydrogen atom, a halogen atom, a methyl group, an ethyl group, or R ₁ and R ₂ , R ₃ and R ₄ , R ₅ and R ₆ . Each may form an alkylidene group having 1 to 2 carbon atoms.)
And preferably any of the following.

[2]
The ethylene / α-olefin / cyclic olefin copolymer (A) has a polystyrene-equivalent weight average molecular weight of 80,000 to 400,000 by gel permeation chromatography, and Mw / Mn is 4 or less. Viscosity index improver for lubricating oil.
[3]
The viscosity index improver for lubricating oil, wherein the α-olefin having 3 to 20 carbon atoms is propylene.
[4]
The viscosity index improver for a lubricating oil, wherein the cyclic olefin is 2-norbornene or 5-ethylidene-2-norbornene.

[5]
1 to 50% by mass of the ethylene / α-olefin / cyclic olefin copolymer (A) and 50 to 99% by mass of the oil (B) (however, the mass% of the (A) and (B) is an additive) A lubricating oil additive composition comprising (calculated based on the total amount of (A) and (B) in the composition).
[6]
A lubricating oil composition comprising the ethylene / α-olefin / cyclic olefin copolymer (A) and a lubricating oil base (BB), wherein 100% by mass of the lubricating oil composition contains the ethylene / α-olefin / A lubricating oil composition containing 0.01 to 30% by mass of a cyclic olefin copolymer (A).

[7]
The lubricating oil composition comprising a soot dispersant other than the ethylene / α-olefin / cyclic olefin copolymer (A) in an amount of 0 to 0.1% by mass in 100% by mass of the lubricating oil composition.
[8]
Said lubricating oil composition which contains a pour point depressant (C) in the quantity of 0.05-5 mass% in 100 mass% of lubricating oil compositions.

  The viscosity index improver for lubricating oils of the present invention has the effect of improving the soot dispersibility, low temperature characteristics (CCS viscosity), and fuel economy at high temperatures (HTHS viscosity) of the lubricating oil composition. Further, the lubricating oil composition comprising the viscosity index improver for lubricating oil or the additive composition for lubricating oil of the present invention is excellent in soot dispersibility, low temperature characteristics (CCS viscosity), and fuel efficiency at high temperatures (HTHS viscosity). .

Next, the present invention will be specifically described.
[Viscosity index improver for lubricating oil]
The viscosity index improver for lubricating oil of the present invention comprises an ethylene / α-olefin / cyclic olefin copolymer (A) described later.

[Ethylene / α-olefin / Cyclic olefin copolymer (A)]
The ethylene / α-olefin / cyclic olefin copolymer (A) of the present invention contains 18 to 85.5 mol% of structural units derived from ethylene, and is at least one selected from α-olefins having 3 to 20 carbon atoms. Melting peak measured by a differential scanning calorimeter (DSC) containing 9 to 76 mol% of structural units derived from α-olefin and 5 to 10 mol% of structural units derived from cyclic olefin represented by the following general formula (I). Is not present, and the glass transition temperature Tg is −12 ° C. or lower.
Formula (I)

一般式（Ｉ）中、Ｒ₁〜Ｒ₆は互いに同一でも異なっていてもよく、水素原子、ハロゲン原子、メチル基、エチル基、あるいはＲ₁とＲ₂、Ｒ₃とＲ₄、Ｒ₅とＲ₆でそれぞれアルキリデン基を形成していてもよい。

In the general formula (I), R _{1 to} R ₆ may be the same as or different from each other, and may be a hydrogen atom, a halogen atom, a methyl group, an ethyl group, or R ₁ and R ₂ , R ₃ and R ₄ , R ₅ R ₆ may each form an alkylidene group.

The cyclic olefin is preferably 2-norbornene (NB) or 5-ethylidene-2-norbornene (ENB) from the viewpoints of handling properties and heat resistance.
The structural unit derived from ethylene is preferably 30 to 70 mol%, and more preferably 40 to 60 mol%. The structural unit derived from at least one α-olefin selected from α-olefins having 3 to 20 carbon atoms is preferably 25 to 65 mol%, and more preferably 32 to 54.5 mol%. The structural unit derived from the cyclic olefin represented by the general formula (I) is preferably 5 to 9 mol%, and more preferably 5.5 to 8 mol%.

When each structural unit is within the above range, when used as a viscosity index improver for lubricating oil, the resulting lubricating oil composition is preferable because it is excellent in soot dispersibility, low temperature characteristics, and fuel economy.
The ethylene / α-olefin / cycloolefin copolymer (A) of the present invention (1) has no melting peak measured by a differential scanning calorimeter (DSC), and has a glass transition temperature Tg of −50 ° C. to − It is preferable that it is 12 degreeC, and it is more preferable that it is -30 degreeC--12 degreeC. The glass transition temperature Tg can be adjusted by selecting the monomer species and the copolymerization ratio.

  The ethylene / α-olefin / cyclic olefin copolymer (A) of the present invention preferably has a polystyrene-reduced weight average molecular weight in the range of 80,000 to 400,000 by gel permeation chromatography (100). More preferably, it is 3,000-350,000.

In the ethylene / α-olefin / cyclic olefin copolymer (A) of the present invention, (3) Mw / Mn is preferably 4 or less, and more preferably 3 or less.
When the requirements (1), (2), and (3) are within the above ranges, the resulting lubricating oil composition has a soot dispersibility, a low temperature characteristic, and fuel efficiency when used as a viscosity index improver for lubricating oil. It is preferable because it is excellent.

  There is no restriction | limiting in particular as a manufacturing method of the ethylene-alpha-olefin-cyclic olefin copolymer (A) of this invention, It can obtain by a well-known catalyst and a polymerization method. For example, it can be obtained by copolymerizing propylene, ethylene, and a cyclic olefin in the presence of a catalyst mainly composed of a solid titanium component and an organometallic compound, or a metallocene catalyst using a metallocene compound as one component of the catalyst. Among them, a production method using a metallocene catalyst capable of stereoregular polymerization with an isotactic structure is preferable. Examples of such a metallocene catalyst include, for example, WO 98/49212 and WO 2000/01745. The metallocene catalyst described in claims 6 to 8 of International Publication No. 2004/106430, International Publication No. 2005/019283, International Publication No. 2006/025540, International Publication No. 2004/087775 can be given. .

  Specific examples of the metallocene compounds include μ-dimethylsilyl (bis-indenyl) hafnium dimethyl, diphenylmethylene (3-tert-butyl-5-ethylcyclopentadienyl) (2,7-di-tert-butylfull). Olenyl) zirconium dichloride, diphenylmethylene (3-tert-butyl-5-methylcyclopentadienyl) (2,7-di-tert-butylfluorenyl) zirconium dichloride, dimethylmethylene (3-tert-butyl-5 -Methylcyclopentadienyl) (fluorenyl) zirconium dichloride and the like.

Among them, (t-butylamido) -dimethyl (η ⁵ -2-methyl-s-indasen-1-yl) silanetitanium (II) 1,3-pentadiene), bis (4-methylphenyl) methylene (cyclopentadienyl) ) (1,2,3,4,7,8,9,10-octahydro-1,1,4,4,7,7,10,10-octamethyldibenzo (b, h) fluoren-12-yl) When a catalyst such as zirconium dichloride is used, the copolymer property for obtaining the copolymer of the present invention is excellent.

[Additive composition for lubricating oil]
The additive composition for lubricating oil of the present invention comprises 1 to 50% by mass of the ethylene / α-olefin / cyclic olefin copolymer (A) and 50 to 99% by mass of the oil (B) (provided that (A ) And (B) mass% contains (calculated based on the total amount of (A) and (B) in the additive composition).

That is, the amounts of (A) and (B) are amounts when the total of (A) and (B) is 100% by mass.
Examples of the oil (B) contained in the additive composition for lubricating oil include mineral oils and synthetic oils such as poly-α-olefins, diesters, and polyalkylene glycols. A blend is preferably used. Examples of diesters include polyol esters, dioctyl phthalate, and dioctyl sebacate.

  Mineral oil is generally used through a refining process such as dewaxing, and there are several grades depending on the method of refining, but mineral oil containing a wax content of 0.5 to 10% is generally used. For example, a highly refined oil having a low pour point, a high viscosity index, and a composition mainly composed of isoparaffin produced by a hydrogenolysis refining method can be used. Further, a mineral oil having a kinematic viscosity at 40 ° C. of 10 to 200 cSt is generally used.

  As described above, mineral oil is generally used after a refining process such as dewaxing, and there are several grades depending on the refining method, and this grade is defined by API (American Petroleum Institute) classification. Table 1 shows the characteristics of the lubricant bases classified into each group.

表１におけるポリα−オレフィンは、少なくとも炭素数１０以上のα−オレフィンを原料モノマーの一種として重合して得られる炭化水素ポリマーであって、デセン−１を重合して得られるポリデセンなどが例示される。

The poly α-olefin in Table 1 is a hydrocarbon polymer obtained by polymerizing at least an α-olefin having 10 or more carbon atoms as a kind of raw material monomer, and examples thereof include polydecene obtained by polymerizing decene-1. The

Further, the oil (B) used in the present invention is preferably an oil belonging to any one of group (i) to group (iv), and particularly a mineral oil having a kinematic viscosity at 100 ° C. of 1 to 50 mm ² / s. And those having a viscosity index of 80 or more, or poly α-olefins are preferred. The oil (B) is preferably a mineral oil belonging to the group (ii) or the group (iii) or a poly α-olefin belonging to the group (iv). The group (ii) and the group (iii) tend to have a lower wax concentration than the group (i).

In particular, the oil (B) is a mineral oil having a kinematic viscosity at 100 ° C. of 1 to 50 mm ² / s and a viscosity index of 80 or more and belonging to the group (ii) or the group (iii). Or the poly (alpha) -olefin which belongs to group (iv) is the most preferable.

  The additive composition for lubricating oil of the present invention contains the ethylene / α-olefin / cyclic olefin copolymer (A) and the oil (B), and usually the ethylene / α-olefin / cyclic olefin copolymer. 1 to 50% by mass of (A) and 50 to 99% by mass of oil (B) (provided that the mass% of (A) and (B) is the sum of (A) and (B) in the additive composition) Calculated based on the amount). The additive composition for lubricating oil of the present invention preferably contains 2 to 40% by mass of the ethylene / α-olefin / cyclic olefin copolymer (A) and 60 to 98% by mass of the oil (B), and more. Preferably, the ethylene / α-olefin / cycloolefin copolymer (A) is contained in an amount of 3 to 30% by mass and the oil (B) in an amount of 70 to 97% by mass.

  Further, the additive composition for lubricating oil of the present invention may contain components other than the ethylene / α-olefin / cyclic olefin copolymer (A) and the oil (B). Other components include emulsifiers, ashless dispersants (D) other than the component (A), oxidation stabilizers, antiwear agents, and the like. When the additive composition for lubricating oil of the present invention contains other components, it is usually 0 with respect to 100% by mass in total of the propylene / ethylene copolymer (A) and the oil (B). It may be contained in the range of 0.01 to 10% by mass. When the ashless dispersant (D) other than (A) is included, may be contained in the range of 0 to 10% by mass, preferably the mass ratio of the (D) component to the (A) component (D ) / (A) is 0/50 to 50/50.

  The lubricating oil additive composition of the present invention preferably contains the ethylene / α-olefin / cyclic olefin copolymer (A) and the oil (B) in the above-mentioned range. When the lubricating oil composition is produced using the lubricating oil additive composition containing the ethylene / α-olefin / cyclic olefin copolymer (A) and the oil (B) in the above range, the lubricating oil additive is added. By mixing the agent composition and the other components of the lubricating oil composition, a lubricating oil composition having an excellent viscosity increase can be obtained with a small ethylene / α-olefin / cyclic olefin copolymer (A) content. be able to.

  Moreover, since the additive composition for lubricating oil of the present invention is a composition containing oil (B) as described above, the workability when producing the lubricating oil composition is also good, and the lubricating oil composition Can be easily mixed with other ingredients.

  The additive composition for lubricating oil of the present invention can be prepared by mixing the ethylene / α-olefin / cyclic olefin copolymer (A) and the oil (B) by a conventionally known method.

[Lubricating oil composition]
The lubricating oil composition of the present invention contains the above-mentioned ethylene / α-olefin / cyclic olefin copolymer (A) and a lubricating oil base (BB), and preferably further contains other than (A). Contains agents.

First, each component forming the lubricating oil composition of the present invention will be described.
As the ethylene / α-olefin / cyclic olefin copolymer (A) contained in the lubricating oil composition, the above-described lubricating oil viscosity modifier, ethylene / α-olefin / cyclic olefin copolymer (A), is used. .

  Examples of the lubricating oil base (BB) contained in the lubricating oil composition include mineral oils and synthetic oils such as poly α-olefins, diesters, polyalkylene glycols, and the like. A blend is preferably used. Examples of diesters include polyol esters, dioctyl phthalate, and dioctyl sebacate.

  Mineral oil is generally used through a refining process such as dewaxing, and there are several grades depending on the method of refining, but mineral oil containing a wax content of 0.5 to 10% is generally used. For example, a highly refined oil having a low pour point, a high viscosity index, and a composition mainly composed of isoparaffin produced by a hydrogenolysis refining method can be used. Further, a mineral oil having a kinematic viscosity at 40 ° C. of 10 to 200 cSt is generally used.

  As described above, mineral oil is generally used after a refining process such as dewaxing, and there are several grades depending on the refining method, and this grade is defined by API (American Petroleum Institute) classification. The characteristics of the lubricant bases classified into each group are as shown in Table 1 above.

  The poly α-olefin in Table 1 is a hydrocarbon polymer obtained by polymerizing at least an α-olefin having 10 or more carbon atoms as a kind of raw material monomer, and examples thereof include polydecene obtained by polymerizing decene-1. The

Further, the lubricating oil base (BB) used in the present invention is preferably an oil belonging to any one of group (i) to group (iv). Particularly, among mineral oils, the kinematic viscosity at 100 ° C. is 1 to 50 mm ^2. / S and a viscosity index of 80 or more, or poly α-olefin is preferable. Further, as the lubricating oil base (BB), mineral oil belonging to group (ii) or group (iii) or poly α-olefin belonging to group (iv) is preferable. The group (ii) and the group (iii) tend to have a lower wax concentration than the group (i).

In particular, the lubricant base (BB) is a mineral oil having a kinematic viscosity at 100 ° C. of 1 to 50 mm ² / s and a viscosity index of 80 or more, and is classified into group (ii) or group (iii). Most preferred are polyalphaolefins belonging to the group or group (iv).

  Pour point depressants (C) preferably contained in the lubricating oil composition include alkylated naphthalene, alkyl (co) polymer, alkyl acrylate (co) polymer, alkyl fumarate and vinyl acetate. Examples thereof include copolymers, α-olefin polymers, copolymers of α-olefins and styrene, and among them, alkyl methacrylate (co) polymers and alkyl acrylate (co) polymers are preferably used. .

  As described above, the lubricating oil composition of the present invention contains the ethylene / α-olefin / cyclic olefin copolymer (A) and the lubricating oil base (BB), and preferably other than (A). Contains the additive.

  In 100% by mass of the lubricating oil composition, the ethylene / α-olefin / cyclic olefin copolymer (A) is usually 0.01 to 30% by mass, preferably 0.1 to 10% by mass, particularly preferably 0. It is contained in an amount of 5 to 5% by mass. When the ethylene / α-olefin / cyclic olefin copolymer (A) is 0.01% by mass or more, the soot dispersibility is excellent, while the ethylene / α-olefin / cyclic olefin copolymer (A) is 30% by mass. The following lubricating oil composition is excellent in low-temperature fluidity.

  Furthermore, the lubricating oil composition of the present invention is a known lubricating oil additive such as an extreme pressure additive and an antiwear agent, a metal detergent, and the present invention for the purpose of further enhancing the performance as the lubricating oil composition. Ashless dispersant (D) other than component (A), antioxidant, friction modifier, rust inhibitor, corrosion inhibitor, viscosity index improver (E) other than component (A) of the present invention, pour point depressant (C), a rubber swelling agent, an antifoaming agent, a coloring agent, etc. can be added to the lubricating oil composition of the present invention alone or in a combination of several kinds.

  As the extreme pressure additive and the antiwear agent, for example, zinc dithiophosphate, a sulfur compound, a phosphorus compound, or the like can be used. Examples of zinc dithiophosphate include zinc dialkyldithiophosphate having a linear or branched alkyl group having 2 to 18 carbon atoms, zinc diphenyldithiophosphate, and dialkylphenyl having a linear or branched alkyl group having 1 to 18 carbon atoms. Zinc dithiophosphate can be used. Examples of sulfur compounds include disulfides, sulfurized olefins, and sulfurized fats and oils. Examples of phosphorus compounds include zinc dithiophosphates other than the above component (A), phosphoric acid monoesters, and phosphoric acid diesters. Phosphoric acid triesters, phosphorous acid monoesters, phosphorous acid diesters, phosphorous acid triesters, and salts of these esters with amines and alkanolamines can be used.

  As the metallic detergent, for example, neutral, basic or overbased alkaline earth metal sulfonates, alkaline earth metal phenates, alkaline earth metal salicylates, alkaline earth metal phosphonates and the like can be used. Examples of the alkaline earth metal include magnesium, calcium, barium and the like, and magnesium and calcium are particularly preferably used.

  As the ashless dispersant (D) other than the component (A) of the present invention, for example, benzylamine, alkylpolyamine, or a modified product of these by boron compound or sulfur compound, alkenyl succinate, or the like can be used.

As the antioxidant, any of phenolic compounds and amine compounds that are generally used in lubricating oils can be used. For example, 2,6-di-tert-butyl- Alkylphenols such as 4-methylphenol, bisphenols such as methylene-4,4-bis (2,6-di-tert-butyl-4-methylphenol), naphthylamines such as phenyl-α-naphthylamine, dialkyldiphenylamines In addition, phenothiazines can be used.
Examples of the friction modifier include molybdenum dialkyldithiocarbamate having a linear or branched alkyl group having 2 to 18 carbon atoms, molybdenum dialkyldithiophosphate having a linear or branched alkyl group having 2 to 18 carbon atoms, and aliphatic. Alcohol, fatty acid, fatty acid ester, aliphatic amine, aliphatic amine salt, aliphatic amide and the like can be used.

As the rust inhibitor, for example, alkenyl succinic acid, alkenyl succinic acid ester, polyhydric alcohol ester, petroleum sulfonate, dinonyl naphthalene sulfonate and the like can be used.
As the corrosion inhibitor, for example, benzotriazole, thiadiazole, and imidazole compounds can be used.

As the viscosity index improver (E) other than the component (A) of the present invention, a non-dispersed viscosity index improver can be used. Specifically, polymethacrylates, ethylene-propylene copolymers, Polyisobutylene, polystyrene, styrene-diene copolymer and the like can be used.
As the pour point depressant (C), for example, a polymethacrylate polymer compatible with the lubricating base oil to be used can be used.

As the antifoaming agent, for example, silicones such as dimethyl silicone and fluorosilicone can be used.
As the content of the additive, when the total amount of (A), (BB) and the additive is 100% by mass, the amount of these additives is arbitrary, but is usually based on the total amount of the lubricating oil composition. The content of the antifoaming agent is 0.0005 to 0.01% by mass, the content of the viscosity index improver is 0.05 to 20% by mass, and the content of the corrosion inhibitor is 0.005 to 0.2% by mass. %, The content of the ashless dispersant (D) other than the component (A) of the present invention is 0 to 10% by mass, and the content of the viscosity index improver (E) other than the component (A) of the present invention is 0 to 10%. The content of mass% and other additives is about 0.005 to 10 mass%, respectively.

The content of the ashless dispersant (D) other than the component (A) is preferably 0 to 0.1% by mass, and the content of the pour point depressant (C) is 0.05 to 5% by mass. Is preferred.
More preferably, the mass ratio (D) / (A) of the component (D) to the component (A) is 0/10 to 1/10, and the mass ratio of the component (E) to the component (A) (E) / ( A) is 0/10 to 1/10.

  The lubricating oil composition of the present invention is mixed with an ethylene / α-olefin / cyclic olefin copolymer (A) and a lubricating oil base (BB), and, if necessary, other additives by a conventionally known method. It can be prepared by dissolving.

The kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is preferably 5 to 20 mm ² / s, and the upper limit value is more preferably 12 mm ² / s or less, further preferably 11 mm ² / s or less, particularly preferably. Is 10.5 mm ² / s or less. Further, the lower limit value of the kinematic viscosity at 100 ° C. of the lubricating oil composition of the present invention is more preferably 7 mm ² / s or more, and further preferably 9 mm ² / s or more. A lubricating oil composition having a kinematic viscosity at 100 ° C. of 5 mm ² / s or more is excellent in lubricity, and a lubricating oil composition having a kinematic viscosity at 100 ° C. of 20 mm ² / s or less is excellent in low-temperature viscosity and fuel economy.

  The HTHS viscosity at 150 ° C. of the lubricating oil composition of the present invention is not particularly limited, but is preferably 3.5 mPa · s or less, more preferably 3.0 mPa · s or less, and even more preferably 2.8 mPa · s or less. . Further, it is preferably 2.0 mPa · s or more, more preferably 2.1 mPa · s or more, further preferably 2.2 mPa · s or more, particularly preferably 2.3 mPa · s or more, and most preferably 2.4 mPa · s or more. It is. A lubricating oil composition having an HTHS viscosity at 150 ° C. of 2.0 mPa · s or higher is excellent in lubricity, and a lubricating oil composition having an HTHS viscosity at 150 ° C. of 3.5 mPa · s or lower has low temperature viscosity and fuel efficiency. Excellent.

The α-olefin having 3 to 20 carbon atoms constituting the ethylene / α-olefin / cyclic olefin copolymer (A) of the present invention is more preferably propylene.
The lubricating oil composition of the present invention can maintain not only the soot dispersion effect but also the viscosity at low temperatures, particularly the CCS viscosity at -30 ° C. Furthermore, since the fuel efficiency at high temperatures (HTHS viscosity) is excellent and the viscosity decrease due to mechanical shearing is small, the life of the lubricating oil composition is long.

  The lubricating oil composition of the present invention comprises a lubricating oil for automobile engines, a lubricating oil for heavy duty diesel engines, a lubricating oil for marine diesel engines, a lubricating oil for 2-cycle engines, an automatic transmission base oil, a manual transmission oil, a gear oil, and a grease. Etc. can be suitably used. In addition, it is also preferably used as various lubricating oils that require a sludge generation suppressing effect, for example, hydraulic oils for automobiles such as shock absorber oils, hydraulic oils, and the like.

  EXAMPLES Next, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited by these.

[DSC measurement]
The copolymer produced in Example or Comparative Example was preheated for 5 minutes using a hydraulic hot press molding machine set to 190 ° C., then pressurized for 2 minutes, and set to 20 ° C. within 1 minute after pressing. The sheet was placed in a cooling tank and cooled there for 4 minutes to prepare a press sheet having a thickness of 2 mm.

The press sheet stored at 20 ° C. for 4 weeks was used as a test specimen. The DSC measurement was performed using a differential scanning calorimeter (RDC220) manufactured by SEIKO calibrated with indium.
The test specimen was weighed on an aluminum DSC pan so as to be about 10 mg, and the lid was crimped on the pan to form a sealed atmosphere to obtain a sample pan.

A sample pan is placed in the DSC cell and an empty aluminum pan is placed as a reference. The DSC cell was cooled from 20 ° C. (room temperature) to −20 ° C. in a nitrogen atmosphere, held at −20 ° C. for 5 minutes, and then heated to 200 ° C. at 10 ° C./min. (First heating process)
Next, after maintaining at 200 ° C. for 5 minutes, the temperature was decreased at 10 ° C./min, and the DSC cell was cooled to −100 ° C. After holding at −100 ° C. for 5 minutes, the DSC cell was heated to 200 ° C. at 10 ° C./min. The temperature at which the endothermic curve when the temperature rises first tilted toward the endothermic side was defined as the glass transition point at the intersection of the tangent lines of the front and rear linear portions. (Second heating process)

[Weight average molecular weight and molecular weight distribution]
The weight average molecular weight and molecular weight distribution of the copolymer produced or used in Examples or Comparative Examples were measured by the following methods.

(Pretreatment of sample)
30 mg of the copolymer produced or used in Examples or Comparative Examples was dissolved in 20 ml of 0-dichlorobenzene at 145 ° C., and then the solution was filtered through a sintered filter having a pore size of 1.0 μm as an analysis sample.

(GPC analysis)
The average molecular weight and molecular weight distribution curve were determined using gel permeation chromatography (GPC). Calculation was performed in terms of polystyrene.

(measuring device)
Gel permeation chromatograph alliance GPC 2000 (manufactured by Waters)
(Analysis device)
Data processing software Empower2 (Waters)

(Measurement condition)
Two columns TSKgel GMH ₆ -HT and two TSKgel GMH ₆ -HTL (both 7.5 mm in diameter x 30 cm in length, manufactured by Tosoh Corporation)
Column temperature 140 ° C
Mobile phase o-dichlorobenzene (containing 0.025% BHT)
Detector Differential refractometer Flow rate 1 mL / min Sample concentration 0.15% (w / v)
Injection volume 500μL
Sampling time interval 1 second Column calibration Monodisperse polystyrene (manufactured by Tosoh Corporation)
Molecular weight conversion PS conversion / standard conversion method

(Kinematic viscosity)
The kinematic viscosity at 100 ° C. of the lubricating oil compositions prepared in Examples or Comparative Examples was measured based on ASTM D446.

[Cold Cranking Simulator (CCS) viscosity]
The CCS viscosity (−30 ° C.) of the lubricating oil compositions prepared in Examples or Comparative Examples was measured based on ASTM D 2602. The CCS viscosity is used for evaluation of slidability (startability) at a low temperature on the crankshaft, and the smaller the value, the better the low temperature viscosity (low temperature characteristics) of the lubricating oil.

  Specifically, in the lubricating oil composition having the same kinematic viscosity using the copolymer (lubricating oil viscosity modifier) produced or used in Examples or Comparative Examples having substantially the same weight average molecular weight, the CCS viscosity The lower the value, the better the fuel efficiency at low temperatures.

[Shear Stability Index (SSI)]
The SSI of the lubricating oil compositions prepared in the examples or comparative examples was measured based on ASTM D3945. SSI is a measure of the loss of kinematic viscosity due to the fact that the copolymer component in the lubricating oil undergoes elasticity under the crown and the molecular chain is broken. The larger the SSI, the greater the loss of kinematic viscosity. Indicates.

[Oxidation stability (ISOT)]
JIS K 2514: 1996 4. In accordance with the method for testing the oxidation stability of lubricating oil for internal combustion engines, the oil is deteriorated under conditions of oil temperature 165.5 ° C. and 144 hours, and the kinematic viscosity at 100 ° C. of the deteriorated oil is measured based on ASTM D446. The viscosity ratio was calculated from the kinematic viscosity after the test / the kinematic viscosity before the test. In addition, JIS K 2501: 2003 7. The total acid value was measured from the total acid value after the test-the total acid value before the test.

[HTHS viscosity]
The viscosity at 150 ° C. was measured based on HTHS (High Temperature High Shear) viscosity (mPa · s) ASTM D4683 of the lubricating oil compositions prepared in Examples or Comparative Examples.

[Soot dispersibility test]
The ability to suppress the increase in viscosity caused by soot and keep the soot in suspension can be measured by a bench test described in the present specification. A base oil and a copolymer component are prepared to prepare a prescription oil. Add carbon black powder to the prescription oil. The kinematic viscosity at 100 ° C. of the carbon black dispersion is measured by the test method described in ASTM D445.

  Carbon black (MA100 manufactured by Mitsubishi Chemical Co., Ltd.) corresponding to 3 mass% of the mass was dispersed with respect to 200 mL of the lubricating oil composition using a homogenizer at 10,000 rpm for 30 minutes.

Storage stability 100 cc of test oil was collected in a precipitation tube and allowed to stand at room temperature for 28 days, and the volume of insoluble matter settled on the bottom of the precipitation tube was measured. The evaluation criteria in Table 3 are as follows.
After standing, the presence or absence of sediment and the blackness of the supernatant were compared visually.
○: There is no sediment at the bottom of the sedimentation tube and the blackness of the supernatant is high. Dispersibility is good. X: There is a sediment at the bottom of the sedimentation tube, and the supernatant is thin.

Viscosity ratio The kinematic viscosity immediately before and after carbon black dispersion and the kinematic viscosity after standing at room temperature for 28 days were measured. The viscosity increase inhibitory effect at the time of soot mixing was evaluated by the viscosity ratio obtained by dividing the kinematic viscosity after dispersion by the kinematic viscosity before dispersion.
Viscosity ratio = kinematic viscosity of carbon black mixed oil / kinematic viscosity of new oil This test evaluates the effect of suppressing the increase in viscosity when soot is mixed into the lubricating oil. It shows that the effect is excellent.

[Polymerization Example 1]
0.6 L of toluene and 10.0 g of 2-norbornene (NB) were charged into a 1.0 L glass flask sufficiently purged with nitrogen, and the system was heated to 70 ° C. Thereafter, ethylene was circulated at 40 L / h and propylene at 160 L / h under normal pressure. Subsequently, 0.6 mmol of triisobutylaluminum was added, and (4-methylphenyl) methylene (cyclopentadienyl) (1,2,3,4,7,8,9,10-octahydro-1,1, 4,4,7,7,10,10-Octamethyldibenzo (b, h) fluoren-12-yl) zirconium dichloride 0.009mmol and triphenylcarbenium tetrakis (pentafluorophenyl) borate 0.09mmol The polymerization was started. While continuously supplying ethylene and propylene, polymerization was performed at 70 ° C. for 18 minutes under normal pressure. A small amount of isobutyl alcohol was added to the system to stop the polymerization, and then the polymer was precipitated by pouring the obtained polymerization solution into a large amount of methanol. The resulting polymer was collected by filtration and dried overnight at 80 ° C. under reduced pressure. As a result, 57.6 g of an ethylene / propylene / norbornene copolymer was obtained.

The bis (4-methylphenyl) methylene (cyclopentadienyl) used here (1,2,3,4,7,8,9,10-octahydro-1,1,4,4,7,7 , 10,10-octamethyldibenzo (b, h) fluoren-12-yl) zirconium dichloride was synthesized by the method described in JP-A No. 2004-182715.
The properties of the obtained polymer are shown in Table 2.

[Polymerization Example 2]
Into a 1 L stirring blade added pressure continuous polymerization reactor sufficiently purged with nitrogen, dehydrated and purified n-hexane was added at a flow rate of 1.8 L / h, and (C ₆ H ₅ ) ₃ CB (C ₆ F ₅ ) A toluene solution prepared by mixing ₄ at a concentration of 0.18 mmol / L at a flow rate of 125 mL / h, bis (4-methylphenyl) methylene (cyclopentadienyl) (1,2,3,4,7,8 , 9,10-Octahydro-1,1,4,4,7,7,10,10-octamethyldibenzo (b, h) fluoren-12-yl) zirconium dichloride mixed at a concentration of 0.15 mmol / L The hexane solution prepared by mixing the prepared hexane solution at a flow rate of 30 mL / h and triisobutylaluminum at a concentration of 20 mmol / L was continuously supplied at a flow rate of 50 mL / h. At the same time, ethylene was continuously supplied at a flow rate of 29 g / hr, propylene at a flow rate of 102 g / hr, 5-ethylidene-2-norbornene (ENB) at a flow rate of 61 g / hr, and hydrogen at a flow rate of 0.2 normal L / h. Supplied. The temperature of the polymerization reactor was adjusted to 80 ° C. by circulating a refrigerant through a jacket provided on the outer periphery of the polymerization reactor, and continuous solution polymerization was performed under conditions of a pressure of 3.6 MPa-G and a stirring rotational speed of 800 rpm.

  The solution containing the ethylene / propylene / ENB copolymer produced as a result of the polymerization under the above-described conditions is ethylene through a discharge port provided at the top of the polymerization reactor so as to maintain a liquid volume in the polymerization reactor of 1 L. -The propylene / ENB copolymer was continuously discharged at a rate of 92 g / hr. The obtained polymerization solution was put into a large amount of methanol to precipitate an ethylene / propylene / ENB copolymer. The ethylene / propylene / ENB copolymer was dried under reduced pressure at 130 ° C. for 24 hours.

The bis (4-methylphenyl) methylene (cyclopentadienyl) used here (1,2,3,4,7,8,9,10-octahydro-1,1,4,4,7,7 , 10,10-octamethyldibenzo (b, h) fluoren-12-yl) zirconium dichloride was synthesized by the method described in JP-A No. 2004-182715.
Table 2 shows the properties of the obtained copolymer.

[Polymerization Example 3]
Into a 310 L stirring blade added pressure continuous polymerization reactor sufficiently purged with nitrogen, dehydrated and purified n-hexane was supplied at a flow rate of 31.9 L / h, and (C ₆ H ₅ ) ₃ CB (C ₆ F ₅ Hexane slurry prepared by mixing ₄ at a concentration of 0.1 mmol / L at a flow rate of 5.5 L / h, bis (4-methylphenyl) methylene (cyclopentadienyl) (1,2,3,4,7 , 8,9,10-octahydro-1,1,4,4,7,7,10,10-octamethyldibenzo (b, h) fluoren-12-yl) zirconium dichloride at a concentration of 0.2 mmol / L The mixed hexane solution was continuously supplied at a flow rate of 0.6 L / h, and the hexane solution prepared by mixing triisobutylaluminum at a concentration of 1 mmol / liter was continuously supplied at a flow rate of 1 L / h (39.0 L / h in total). . At the same time, ethylene is supplied at a flow rate of 3.7 kg / hr, propylene is supplied at a flow rate of 3.7 kg / hr, 5-ethylidene-2-norbornene (ENB) is supplied at a flow rate of 2.5 kg / hr, and hydrogen is supplied at 50 normal L / h. The continuous solution polymerization was performed under the conditions of a polymerization temperature of 80 ° C., a total pressure of 1.2 MPa-G, and a stirring rotational speed of 190 rpm. The refrigerant is circulated through a jacket provided on the outer periphery of the polymerization reactor, and the gas phase part is forcibly circulated using a separately installed gas blower, and this is cooled by a heat exchanger, thereby Removal was performed.

  The hexane solution containing the ethylene / propylene / ENB copolymer produced as a result of the polymerization under the above conditions is provided with a discharge port provided at the bottom of the polymerization reactor so as to maintain an average solution volume of 100 L in the polymerization reactor. The ethylene / propylene / ENB copolymer was continuously discharged at a rate of 5.6 kg / hr. The obtained polymerization solution was put into a large amount of methanol to precipitate an ethylene / propylene / ENB copolymer. The ethylene / propylene / ENB copolymer was dried under reduced pressure at 130 ° C. for 24 hours.

The bis (4-methylphenyl) methylene (cyclopentadienyl) used here (1,2,3,4,7,8,9,10-octahydro-1,1,4,4,7,7 , 10,10-octamethyldibenzo (b, h) fluoren-12-yl) zirconium dichloride was synthesized by the method described in JP-A No. 2004-182715.
Table 2 shows the properties of the obtained copolymer.

[Polymerization Example 4]
To a glass flask having an internal volume of 0.5 L that was sufficiently purged with nitrogen, 0.3 L of toluene and 15.0 g of 2-norbornene (NB) were charged, and the temperature in the system was raised to 30 ° C. Thereafter, ethylene was circulated at 80 L / h and propylene at 20 L / h under normal pressure. Subsequently, 0.3 mmol of triisobutylaluminum was added, and bis (4-methylphenyl) methylene (cyclopentadienyl) (1,2,3,4,7,8,9,10-octahydro-1,1 , 4,4,7,7,10,10-Octamethyldibenzo (b, h) fluoren-12-yl) zirconium dichloride 0.003mmol and triphenylcarbenium tetrakis (pentafluorophenyl) borate 0.03mmol Then, polymerization was started. Polymerization was carried out for 60 minutes at 30 ° C. under normal pressure while continuously supplying ethylene and propylene. A small amount of isobutyl alcohol was added to the system to stop the polymerization, and then the polymer was precipitated by pouring the obtained polymerization solution into a large amount of methanol. The resulting polymer was collected by filtration and dried overnight at 80 ° C. under reduced pressure. As a result, 12.7 g of an ethylene / propylene / NB copolymer was obtained.

The bis (4-methylphenyl) methylene (cyclopentadienyl) used here (1,2,3,4,7,8,9,10-octahydro-1,1,4,4,7,7 , 10,10-octamethyldibenzo (b, h) fluoren-12-yl) zirconium dichloride was synthesized by the method described in JP-A No. 2004-182715.
Table 2 shows the properties of the obtained copolymer.

[Polymerization Comparative Example 1]
Polymerization Comparative Example 1 is SHELLVIS (trademark) 151 available from Infineum. Table 2 shows the properties of the obtained copolymer.

[Polymerization Comparative Example 2]
Polymerization comparative example 2 was synthesize | combined by the method as described in international publication 2000/60032. Table 2 shows the properties of the obtained copolymer.

[Polymerization Comparative Example 3]
To a glass flask having an internal volume of 0.5 L that was sufficiently purged with nitrogen, 0.3 L of toluene and 2.5 g of 2-norbornene (NB) were charged, and the system was heated to 40 ° C. Thereafter, ethylene was circulated at 20 L / h and propylene at 80 L / h under normal pressure. Subsequently, 0.3 mmol of triisobutylaluminum was added, and bis (4-methylphenyl) methylene (cyclopentadienyl) (1,2,3,4,7,8,9,10-octahydro-1,1 , 4,4,7,7,10,10-Octamethyldibenzo (b, h) fluoren-12-yl) zirconium dichloride 0.003mmol and triphenylcarbenium tetrakis (pentafluorophenyl) borate 0.03mmol Then, polymerization was started. Polymerization was carried out for 45 minutes at 40 ° C. under normal pressure while continuously supplying ethylene and propylene. A small amount of isobutyl alcohol was added to the system to stop the polymerization, and then the polymer was precipitated by pouring the obtained polymerization solution into a large amount of methanol. The resulting polymer was collected by filtration and dried overnight at 80 ° C. under reduced pressure. As a result, 14.4 g of an ethylene / propylene / norbornene copolymer was obtained.

The bis (4-methylphenyl) methylene (cyclopentadienyl) used here (1,2,3,4,7,8,9,10-octahydro-1,1,4,4,7,7 , 10,10-octamethyldibenzo (b, h) fluoren-12-yl) zirconium dichloride was synthesized by the method described in JP-A No. 2004-182715.
Table 2 shows the properties of the obtained copolymer.

[Polymerization Comparative Example 4]
To a glass flask having an internal volume of 0.5 L that was sufficiently purged with nitrogen, 0.3 L of toluene and 5.0 g of 2-norbornene (NB) were charged, and the system was heated to 30 ° C. Thereafter, ethylene was circulated at 20 L / h and propylene at 80 L / h under normal pressure. Subsequently, 0.3 mmol of triisobutylaluminum was added, and bis (4-methylphenyl) methylene (cyclopentadienyl) (1,2,3,4,7,8,9,10-octahydro-1,1, Add 0.003mmol of 4,4,7,7,10,10-octamethyldibenzo (b, h) fluoren-12-yl) zirconium dichloride and 0.03mmol of triphenylcarbenium tetrakis (pentafluorophenyl) borate The polymerization was started. Polymerization was carried out for 60 minutes at 30 ° C. under normal pressure while continuously supplying ethylene and propylene. A small amount of isobutyl alcohol was added to the system to stop the polymerization, and then the polymer was precipitated by pouring the obtained polymerization solution into a large amount of methanol. The resulting polymer was collected by filtration and dried overnight at 80 ° C. under reduced pressure. As a result, 12.7 g of an ethylene / propylene / norbornene copolymer was obtained.

The bis (4-methylphenyl) methylene (cyclopentadienyl) used here (1,2,3,4,7,8,9,10-octahydro-1,1,4,4,7,7 , 10,10-octamethyldibenzo (b, h) fluoren-12-yl) zirconium dichloride was synthesized by the method described in JP-A No. 2004-182715.
Table 2 shows the properties of the obtained copolymer.

[Example 1] Using the polymer of polymerization example 1, the performance evaluation and the soot dispersion evaluation of the lubricating oil were performed with the respective formulations shown in Table 3. The results are shown in Table 3.
[Example 2] Using the polymer of polymerization example 2, the performance evaluation and the soot dispersion evaluation of the lubricating oil were performed with the respective formulations shown in Table 3. The results are shown in Table 3.
[Example 3] Using the polymer of polymerization example 3, the performance evaluation and the soot dispersion evaluation of the lubricating oil were performed with the respective formulations shown in Table 3. The results are shown in Table 3.
[Example 4] Using the polymer of polymerization example 4, the performance evaluation and the soot dispersion evaluation of the lubricating oil were performed with the respective formulations shown in Table 3. The results are shown in Table 3.
[Comparative Example 1] Using the polymer of Polymerization Comparative Example 1, the performance evaluation and the soot dispersion evaluation of the lubricating oil were performed with the respective formulations shown in Table 3. The results are shown in Table 3.
[Comparative Example 2] Using the polymer of Polymerization Comparative Example 2, the performance evaluation and the soot dispersion evaluation of the lubricating oil were carried out for each formulation shown in Table 3. The results are shown in Table 3.
[Comparative Example 3] Using the polymer of Polymerization Comparative Example 3, the performance evaluation and the soot dispersion evaluation of the lubricating oil were carried out for each formulation shown in Table 3. The results are shown in Table 3.

Claims (8)

18 to 85.5 mol% of structural units derived from ethylene, 9 to 76 mol% of structural units derived from at least one α-olefin selected from α-olefins having 3 to 20 carbon atoms, and the following general formula (I Ethylene / α having a glass transition temperature Tg of −12 ° C. or less without a melting peak measured by a differential scanning calorimeter (DSC). -Viscosity index improver for lubricating oil comprising olefin / cyclic olefin copolymer (A).
Formula (I)

(In the formula, R _{1 to} R ₆ may be the same as or different from each other, and may be a hydrogen atom, a halogen atom, a methyl group, an ethyl group, or R ₁ and R ₂ , R ₃ and R ₄ , R ₅ and R ₆ . Each may form an alkylidene group having 1 to 2 carbon atoms.)   The ethylene / α-olefin / cyclic olefin copolymer (A) has a polystyrene-equivalent weight average molecular weight of 80,000 to 400,000 by gel permeation chromatography, and Mw / Mn is 4 or less. Item 2. The viscosity index improver for lubricating oils according to Item 1.   The viscosity index improver for lubricating oil according to claim 1 or 2, wherein the α-olefin having 3 to 20 carbon atoms is propylene.   The viscosity index improver for lubricating oil according to any one of claims 1 to 3, wherein the cyclic olefin is 2-norbornene or 5-ethylidene-2-norbornene.   1 to 50% by mass of the ethylene / α-olefin / cyclic olefin copolymer (A) according to any one of claims 1 to 4 and 50 to 99% by mass of an oil (B) (provided that (A ) And (B) mass% is calculated based on the total amount of (A) and (B) in the additive composition).   A lubricating oil composition comprising the ethylene / α-olefin / cyclic olefin copolymer (A) according to any one of claims 1 to 4 and a lubricating oil base (BB). A lubricating oil composition containing 0.01 to 30% by mass of the ethylene / α-olefin / cyclic olefin copolymer (A) in 100% by mass.   The lubricating oil according to claim 6, comprising an ashless dispersant other than the ethylene / α-olefin / cyclic olefin copolymer (A) in an amount of 0 to 0.1% by mass in 100% by mass of the lubricating oil composition. Composition.   The lubricating oil composition according to claim 6 or 7, wherein the pour point depressant (C) is contained in an amount of 0.05 to 5% by mass in 100% by mass of the lubricating oil composition.