WO2004041977A1

WO2004041977A1 - Lubricating oil

Info

Publication number: WO2004041977A1
Application number: PCT/JP2003/014032
Authority: WO
Inventors: Naozumi Arimoto; Tetsuo Okawa
Original assignee: Nippon Oil Corporation
Priority date: 2002-11-05
Filing date: 2003-10-31
Publication date: 2004-05-21
Also published as: JP2004155873A; EP1559772B1; CN1711345A; CN100455646C; EP1559772A4; US20060105921A1; JP4571776B2; EP1559772A1; AU2003280701A1

Abstract

A lubricating oil composition which comprises (A) a base oil for a lubricating oil comprising a mineral oil, a synthetic oil or a mixture thereof, (B) a nitrogen-containing compound having at least one alkyl group or alkenyl group and having a number average molecular weight of 900 or more and/or a derivative thereof in an amount of 0.01 to 0.20 mass % as a nitrogen content on the basis of the total amount of the composition, and (C) a viscosity index improver having a weight average molecular weight of 40,000 or less, and which has a viscosity index of 160 or higher and a kinematic viscosity at 40°C of 20 to 30 mm2/s. The lubricating oil composition has a low viscosity and also is capable of exhibiting good anti-wear characteristics both in an early stage of use and after the use for a long period, and thus can be advantageously used for an automatic transmission or a continuously variable transmission.

Description

Description Lubricating oil composition Technical field

The present invention relates to a lubricating oil composition, and more particularly, to a low-viscosity lubricating oil composition having excellent anti-wear properties, and particularly capable of maintaining anti-wear properties for a long period of time. Background art

In recent years, there has been an urgent need to reduce carbon dioxide emissions against the background of environmental issues, and improving fuel efficiency of automobiles has become a more important issue than ever. As a means of improving the fuel efficiency of automobiles, it is considered effective to reduce friction in the boundary lubricating oil region by reducing the stirring resistance by lowering the viscosity of the lubricating oil used and by using a friction reducing agent. .

For low-viscosity lubricating oils for internal combustion engines, fuel-saving engine oils containing a high molecular weight viscosity index improver or using a friction reducing agent such as an organic molybdenum compound have been proposed (for example, (See JP 2001-181664 A). In addition, in an automatic transmission composed of a torque converter, a wet clutch, a gear bearing mechanism, an oil pump, and a hydraulic control mechanism, it is necessary to optimize the friction characteristics of a wet clutch. A low friction reducing agent is not usually used, and it is considered effective to lower the viscosity of the lubricating oil. Fuel efficiency is expected to be improved by reducing the stirring resistance of the torque converter and oil pump. Since the lower viscosity of lubricating oil directly leads to deterioration of anti-wear properties, it is difficult to achieve both fuel efficiency and wear resistance by lowering the viscosity. Will be given priority.

Conventional transmission oils for automobiles include those that can maintain various performances such as transmission characteristics for a long period of time, such as synthetic oil and / or mineral oil-based lubricating base oils, antiwear agents, extreme pressure agents, metal detergents, and none. A compound in which an ash dispersant, a friction modifier and the like have been optimized and blended has been disclosed (see, for example, JP-A-3-39399, JP-A-7-268375, and JP-A-2000-63869). The viscosity index improver is generally selected from those having an average molecular weight of 1,000 to 1,000, 000, and a lubricating oil containing a low molecular weight viscosity index improver. Examples thereof include, for example, 1 to 15% by weight of a monoolefin polymer or copolymer having a number average molecular weight of 1,000 to 10,000, and a saturated aliphatic monovalent having an average molecular weight of 5,000 to 50,000. 1 to 5 mass of an ester copolymer of alcohol and methallylic acid. / ₀ and an ethylene / α-olefin copolymer having a number average molecular weight of 26,000 to 40,000 (see Japanese Patent Application Laid-Open No. 61-9497). automatic transmission fluid composition semisynthetic containing by weight ^_0/0 (Hei 1 _ 1 6 8 798 JP) Or, the number average molecular weight of 9, 000 to 23, 000 27 weight polymerase Tatari rate ⁰ /. A semi-synthetic automatic transmission oil composition containing about 34% by weight (JP-A-1-271494) and the like are disclosed.

However, since none of these compositions are aimed at improving fuel efficiency, their kinematic viscosities are high and the initial and long-term use is the most important issue when lubricating oil is reduced in viscosity. In addition to the fact that the effect of the rubber on the anti-wear property has not been studied at all, the optimization of the viscosity index improver with other additives has not been sufficiently studied. Further, the kinematic viscosity of the automotive automatic transmission fluid currently on the market is generally in the range of 30 to 5 OmmVs at 40 ° C, and therefore, a low viscosity oil having both improved fuel efficiency and anti-wear properties is obtained. It is believed that the transmission oil is substantially absent. Disclosure of the invention

Accordingly, the present invention has been made in view of such circumstances, and it is an object of the present invention to provide a lubricating oil composition having low viscosity and sufficient anti-wear properties even after initial and long-term use. An object of the present invention is to provide a low-viscosity lubricating oil composition suitable for an engine or a continuously variable transmission.

The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that a low-viscosity lubricating oil obtained by optimizing and blending a specific nitrogen-containing compound and a viscosity index improver with a specific molecular weight into a lubricating base oil. The inventors have found that the composition can solve the above problems, and have completed the present invention. That is, the present invention provides (A) a lubricating base oil comprising a mineral oil, a synthetic oil or a mixture thereof, and (B) a nitrogen-containing compound having at least one alkyl group or alkenyl group having a number average molecular weight of 900 or more. And / or a derivative thereof, based on the total amount of the composition, as a nitrogen content of 0.01 to 0.20% by mass, and (C) a viscosity having a weight average molecular weight of 40,000 or less. The index improver is compounded so that the viscosity index of the composition is at least 160 and the kinematic viscosity at 40 ° C of the composition is 20 to 30 mm ² / s. Lubricating oil composition.

The component (B) is preferably a nitrogen-containing compound having two alkyl groups or alkenyl groups having a number average molecular weight of 1200 or more and Z or a derivative thereof.

The lubricating oil composition of the present invention may further comprise, as the component (B), a nitrogen-modifying compound, which is a nitrogen-containing compound having at least one alkyl group or alkenyl group having a number average molecular weight of 900 or more. It is preferable that the boron content be 0.02% by mass or more based on the total amount of the substance and essential.

The boron-modified compound is preferably a boron-modified compound of a nitrogen-containing compound having at least one alkyl group or alkylene group having a number average molecular weight of 1200 or more.

In addition, the boron-modified compound is preferably a boron-modified compound of a nitrogen-containing compound having two alkyl groups or alkoxyl groups having a number average molecular weight of 1200 or more. Further, the boron-modified compound is preferably a boron-modified compound of a nitrogen-containing compound having two alkyl groups or two alkenyl groups having a number average molecular weight of 170 or more. The mass ratio (B / N ratio) of boron and nitrogen in the boron-modified compound is preferably 0.01 to 3.

Further, the component (B) is preferably a boron-modified succinimide of a bis-type succinimide having a poly (iso) butenyl group having a number average molecular weight of 20 ° 0 or more. The component (B) is a bis-type succinimide having a poly (iso) butenyl group having a number average molecular weight of 900 to less than 200, and a number average molecular weight of 200 or more. Poly

It is preferable to use a combination of a bis-type succinimide having an (iso) butenyl group and a boron-modified succinimide. Further, the lubricating oil composition of the present invention is preferably used for an automatic transmission or a continuously variable transmission.

The present invention also relates to a method for maintaining wear resistance of an automatic transmission or a continuously variable transmission, wherein the method uses the lubricating oil composition. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail.

The component (A) in the present invention is a lubricating base oil composed of mineral oil, synthetic oil, or a mixture thereof, and is not particularly limited, and is usually used as a base oil of a lubricating oil composition. If used, mineral oil and synthetic oil can be used.

As an example of mineral base oils, lubricating oil fractions obtained by atmospheric and vacuum distillation of crude oil are subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining. And paraffinic and naphthenic mineral oil-based lubricating base oils and normal paraffins, which are appropriately combined with refining treatments such as sulfuric acid washing and clay treatment.

Examples of synthetic base oils include poly-α-olefin (polybutene, 1-octene oligomer, 1-decene oligomer, ethylene-propylene oligomer, etc.) and hydrides, isobutene oligomers and the like. Hydrides, isoparaffins, alkylbenzenes, alkylnaphthalenes, diesters (ditridecyl glutarate, di-2-ethylhexyl adipate, disodecyl adipate, ditridecyl adipate, di-21-ethylhexyl sebacate, etc.), polyols Esters (trimethylolpropane caprylate, trimethylolpropaneperalgonate, pentaerythritol tonole 2-ethylhexanoate, pentaerythritol peralgonate, etc.), polyoxyalkylene glycolonole, dianolequinolesiphenylenole Athenole, polypheninoleatenole and the like.

The lubricating base oil of the present invention may be a mixture of two or more mineral base oils or a mixture of two or more kinds of synthetic base oils, and may be a mixture of a mineral base oil and a synthetic base oil. It does not matter. The mixing ratio of two or more base oils in the above mixture can be arbitrarily selected.

Although the kinematic viscosity of these lubricating base oils in the present invention is not particularly limited, the lower limit of the kinematic viscosity at 100 ° C. is l mm ² Zs, preferably 2 mm ² / s. The upper limit of the kinematic viscosity at 100 ° C. is desirably 5 mm ² Zs, preferably 4 mm ² / s, and particularly preferably 3.5 mm ² / s. By setting the kinematic viscosity of the lubricating base oil at 100 ° C to lmm ² Zs or more, an oil film is sufficiently formed, the lubricating property is excellent, and the evaporation loss of the base oil under high temperature conditions is reduced. It is possible to obtain a smaller lubricating oil composition Become. On the other hand, when the kinematic viscosity at 100 ° C. is 5 mm ² / s or less, the fluid resistance is reduced, so that it is possible to obtain a lubricating oil composition having a small friction resistance at a lubricating point.

The viscosity index of these lubricating base oils in the present invention is not particularly limited, but the viscosity index is desirably 80 or more, preferably 90 or more, and particularly preferably 110 or more. By setting the viscosity index to 80 or more, it is possible to obtain a composition having excellent anti-wear properties after long-term use.

The component (B) of the present invention is a nitrogen-containing compound having at least one alkyl group or alkenyl group having a number average molecular weight of 900 or more and Z or a derivative thereof, and one or two selected arbitrarily from these. More than one kind can be blended.

As the component (B), specifically, for example,

(B-1) a succinimide having at least one alkyl group or alkenyl group having a number average molecular weight of 900 or more or a derivative thereof

(B-2) Benzylamine having at least one alkyl or alkenyl group having a number average molecular weight of 900 or more or a derivative thereof

(B-3) a polyamine having at least one alkyl group or alkenyl group having a number average molecular weight of 900 or more or a derivative thereof

And one or more compounds selected from the above.

More specifically, examples of the above-mentioned (B-1) succinimide include compounds represented by the following formula (1) or (2).

In the above formula (1), R ¹ represents an alkyl group or an alkenyl group having a number average molecular weight of 900 or more, and a represents an integer of 1 to 5, preferably 2 to 4.

In the formula (2), R ² and R ³ each independently represent an alkyl group or an alkenyl group having a number average molecular weight of 900 or more, and b represents an integer of 0 to 4, preferably 1 to 3. ing. The imidized succinic acid is a so-called mono-type succinimide as shown in the formula (1) in which succinic anhydride is added to one end of a polyamine when imidization is performed. There is a so-called bis-type succinic acid imid represented by the formula (2) to which succinic acid is added. As the component (B-1), any of them can be used. It is preferable to use a bis-type, that is, a succinimide having two alkyl groups or alkenyl groups having a number average molecular weight of 900 or more, because the anti-wear property is easily maintained.

More specifically, examples of the above (B-2) benzylamine include compounds represented by the following formula (3).

In the formula (3), R ⁴ represents an alkyl group or an alkenyl group having a number average molecular weight of 900 or more, and c represents an integer of 1 to 5, preferably 2 to 4.

The method for producing this benzylamine is not limited at all. For example, a polyolefin such as a propylene oligomer, a polybutene, or an ethylene-a-olefin copolymer is reacted with a phenol to form an alkylphenol, which is then subjected to formaldehyde. And polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine by reacting with a Mannich reaction. More specifically, examples of the polyamine (B-3) include compounds represented by the following formula (4).

R—NjH ₂ CH ₂ t¾-H ( ⁴ ) In the above formula (4), R ⁵ represents an alkyl group or an alkenyl group having a number average molecular weight of 900 or more, and d is 1 to 5, preferably 2 to 5. Indicates an integer of 4.

The method for producing the polyamine is not limited at all. For example, after chlorinating a polyolefin such as propylene oligomer, polybutene, and ethylene- _α -olefin copolymer, ammonia, ethylenediamine, diethylenetriamine, trie It can be obtained by reacting a polyamine such as tylenetetramine, tetraethylenepentamine or pentaethylenehexamine.

As the derivative of the nitrogen-containing compound such as succinic acid imid, benzylamine or polyamine in the component (B) ′, specifically, for example, the nitrogen-containing compound as described above may have 2 to 30 carbon atoms. Monocarboxylic acids (fatty acids, etc.) 2 polycarboxylic acids having 2 to 30 carbon atoms such as oxalic acid, phthalic acid, trimellitic acid, pyromellitic acid or anhydrides thereof, or ester compounds, and 2 to 6 carbon atoms A so-called acid-modified compound in which the remaining amino or Ζ or imino group is partially or entirely neutralized or amidated by the action of an alkylene oxide, a hydroxy (poly) oxyalkylene carbonate or the like; A boron compound such as boric acid, a borate or a borate ester is allowed to act on the above-mentioned nitrogen-containing compound to remove residual amino and / or imino groups. A so-called boron-modified compound in which part or all of the compound has been neutralized or amidified; a sulfur-modified compound obtained by reacting a sulfur-containing compound with the above-described nitrogen-containing compound; and an acid-modified nitrogen-containing compound as described above. , Boron-modified, and sulfur-modified conjugates.

The alkyl group or alkenyl group having a number average molecular weight of 900 or more in the component (II) of the present invention may be linear or branched, but preferred examples thereof include propylene, 1 Olefin oligomers such as butene and isobutylene, and branched alkyl and branched alkenyl groups derived from ethylene and propylene co-oligomers, preferably poly (iso) butenyl groups, and their number average molecular weight Is preferably 1 2 It is at least 0, more preferably at least 1,700, still more preferably at least 2,000, particularly preferably at least 2,300. The upper limit of the number average molecular weight is not particularly limited, but is preferably 500 or less, more preferably 350 or less, and particularly preferably 300 or less. By setting the number average molecular weight of the alkyl group or alkenyl group to 900 or more, it is easy to maintain the wear resistance after long-term use, and by setting the number average molecular weight to 500 or less, the composition has excellent low-temperature fluidity. You can get things.

The nitrogen content of the nitrogen-containing compound of component (B) is arbitrary, but from the viewpoints of wear resistance, oxidation stability and friction characteristics, the nitrogen content is usually 0.01 to 10% by mass. , Preferably 0 .: to 10% by mass.

As the component (B) in the lubricating oil composition of the present invention, an alkyl or alkenyl succinimide having the number average molecular weight as described above can be more preferably used because the anti-wear property is easily maintained. Further, as described above, the number-average molecular weight, particularly the number-average molecular weight of 200 or more alkyl- or boron-modified compound of alkielsuccinimide is excellent in wear prevention properties at the initial stage and after long-term use, It is particularly preferable to include the boron-modified compound as an essential component.

The mass ratio (B / N ratio) of boron and nitrogen in the boron-modified compound of the nitrogen-containing compound is not particularly limited, and is usually 0.01 to 3, but is preferably 0.05 or more. , More preferably 0.1 or more, further preferably 0.2 or more, and preferably 1 or less, more preferably 0.8 or less, and still more preferably 0.6 or less. . By selecting a boron-modified compound having a BZN ratio within the above range, it is possible to obtain a composition having excellent anti-wear properties even after initial use and after long-term use. When the nitrogen-containing compound and its boron-modified carboxylic acid compound are used in combination, for example, a bis-type succinic acid having a poly (iso) butyr group having a number average molecular weight of 900 to less than 2000 is preferred. When the imide is used in combination with a boron-modified compound of a bis-type poly (iso) butercosuccinimide having a number-average molecular weight of 2000 or more, synergistically improve the anti-wear properties during initial and long-term use. Can be. Even in such a case, it is preferable that the mass ratio of boron caused by the boron-modified compound to the total nitrogen caused by the component (B) is also in the above range.

In the lubricating oil composition of the present invention, the lower limit of the content of the component (B) is the total amount of the lubricating oil composition. On the basis, the amount of nitrogen is 0.01% by mass, preferably 0.02% by mass. On the other hand, the upper limit of the content is 0.2% by mass as the amount of nitrogen based on the total amount of the lubricating oil composition. It is preferably 0.18% by mass. If the content of the component (B) is less than 0.01% by mass in terms of nitrogen based on the total amount of the lubricating oil composition, it is difficult to maintain the wear prevention after long-term use due to the component (B). If the content exceeds 2% by mass, the low-temperature fluidity of the lubricating oil composition deteriorates, which is not preferable. When the component (B) is a nitrogen-containing compound having two alkyl groups or alkenyl groups having a number average molecular weight of 1200 or more, the upper limit of the content can be set to 0.07% by mass or less. In the case of a nitrogen-containing compound having two alkyl groups or alkenyl groups having a number average molecular weight of 2,000 or more, sufficient anti-wear properties can be exhibited even if the content is 0.04% by mass or less.

When a boron-modified compound of a nitrogen-containing compound is essentially contained as the component (B), the lower limit of the content is preferably 0.002% by mass or more, more preferably 0.1% by mass or more, as the amount of boron. It is at least 004 mass%, particularly preferably at least 0.008 mass%. The upper limit of the content is preferably 0.05 mass in terms of boron. / ₀ or less, more preferably 0.02% by mass or less, particularly preferably 0.015% by mass or less. By setting the boron content of the boron-modified aldehyde compound as the component (B) within the above-mentioned preferable range, more excellent anti-wear properties can be maintained both at the initial stage and after long-term use.

The component (C) in the present invention is a viscosity index improver having a weight average molecular weight of 40,000 or less, specifically, a non-dispersion type viscosity index improver having a weight average molecular weight of 40,000 or less and / or a dispersion type. And viscosity index improvers.

As the non-dispersion type viscosity index improver, specifically, one or two or more monomers (C—) selected from the compounds represented by the following formulas (5), (6) and (7) Examples thereof include the copolymer (1) and hydrides thereof. On the other hand, as the dispersion-type viscosity index improver, specifically, a copolymer of two or more monomers selected from the compounds represented by the general formulas (8) and (9) or a hydride thereof is used. With an oxygen-containing group introduced into the compound of the general formula (5)

One or more monomers (C-1) selected from the compounds represented by (7) and one or two monomers selected from the compounds represented by the general formulas (8) and (9) Examples thereof include a copolymer with at least one kind of monomer (C-12) or a hydride thereof. R

CH ₂ = C

\ ( Five )

COOR In the above formula (5), R ⁶ represents hydrogen or a methyl group, and R ⁷ represents an alkyl group having 1 to 18 carbon atoms.

Examples of the alkyl group having a carbon number of 1 to 1 8 showing the R ^7, specifically, a methyl group, Echiru group, propyl group, heptyl group, a pentyl group, a hexyl group, a heptyl group, Okuchiru group, Roh group, Examples include a decyl group, a decyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group and the like (these alkyl groups may be linear or branched).

R

CH2 = C

V (6) In the above (6), R ⁸ represents a hydrogen or a methyl group, 1 ⁹ represents a number 1 to 1 2 hydrocarbon group having a carbon.

Specific examples of the hydrocarbon group having 1 to 12 carbon atoms for R ⁹ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and a nonyl group. Groups, decyl, pendecyl, dodecyl, and other alkyl groups (these alkyl groups may be straight-chain or branched); butenyl, pentyl, hexenyl, heptenyl, otathenyl, nonenyl, Alkenyl groups such as decenyl group, pendecenyl group and dodecenyl group (these alkenyl groups may be linear or branched, and the position of the double bond is arbitrary); cyclopentyl group, cyclohexyl group, cyclohexyl group C5-C7 cycloalkyl group such as butyl group; methylcyclopentyl group, dimethylcyclopentyl group, pentyl group of methyl ethynoleic mouth, ethynole Pennole group, Methylhexyl group, Methylhexyl group, Methylethylhexyl group, Methylethylhexyl group, Methylcyclohexyl group, Methylcycloheptyl group, Methylcycloheptyl group, Methylethylsilyl group Alkylcycloalkyl groups having 6 to 11 carbon atoms, such as a mouth heptyl group and a getylcycloheptyl group (the substitution positions of these alkyl groups with cycloalkyl groups are arbitrary); phenyl groups, naphthyl groups, etc. Aryl groups: trialkyl, xylyl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl and other alkylaryl groups having 7 to 12 carbon atoms (these alkyl groups are linear Or the position of substitution on the aryl group is arbitrary); C 7 carbon atoms such as benzyl, phenylethyl, phenylpropyl, phenylbutyl, phenylpentyl, and phenylhexyl groups; To 12 phenylalkyl groups (the alkyl groups may be linear or branched); and the like.

(7)

In the above (7), 0 ¹及Pi 13 ² are each independently a hydrogen atom, residue of § Le Kill alcohol having a carbon number of 1 to 1 8 (_〇_R: R is alkyl having 1 to 1 8 carbon atoms Group) or a residue of a monoalkylamine having 1 to 18 carbon atoms (one NHR: R is an alkyl group having 1 to 18 carbon atoms).

R ¹⁰

I

CH 'C (8)

, 1

COO ^ R ¹¹ "^ ¹

'e

(8) In the formula, R ¹⁰ represents a hydrogen atom or a methyl group, R ¹¹ represents an alkylene group having 1 to 18 carbon atoms, and £ ¹ represents ¹ to 2 nitrogen atoms and an oxygen atom. It shows 0 to 2 amide residues or heterocyclic residues. E is an integer of 0 or 1.

Examples of the alkylene group having 8 to 8 carbon atoms include an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an otathylene group, a nonylene group, a decylene group, a decylene group, Dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, octa And decylene groups (these alkylene groups may be linear or branched). Specific examples of the group represented by E ¹ include a dimethylamino group, a dimethylamino group, a dipropylamino group, a dibutylamino group, an anilino group, a toluidino group, a xylidino group, an acetylamino group, a benzoylamino group, a morpholino group, a pyrrolyl group, Examples thereof include a pyrrino group, a pyridyl group, a methylpyridyl group, a pyrrolidinyl group, a piperidinyl group, a quinonyl group, a pyrrolidonyl group, a pyrrolidno group, an imidazolino group, and a virazino group.

In the above formula (9), R ¹² represents a hydrogen atom or a methyl group; E ² represents an amine residue or a heterocyclic residue containing 1 to 2 nitrogen atoms and 0 to 2 oxygen atoms. I have.

Specific examples of the group representing E ² include a dimethylamino group, a dimethylamino group, a dibutylamino group, a dibutylamino group, an anilino group, a toluidino group, a xylidino group, an acetylamino group, a benzoylamino group, a morpholino group, a pyrrolyl group, and a pyrrolino group. Groups, pyridyl group, methylpyridyl group, pyrrolidinyl group, piperidinyl group, quinonyl group, pyrrolidonyl group, pyrrolidno group, imidazolino group, virazino group and the like.

Preferred as the monomer of the (C-1) component are, specifically, alkyl acrylates having 1 to 18 carbon atoms, alkyl methacrylates having 1 to 18 carbon atoms, and olefins having 2 to 20 carbon atoms. , Styrene, methstyrene, maleic anhydride ester, maleic anhydride amide, and mixtures thereof.

Preferred as the monomer of the component (C-12) are, specifically, dimethylaminomethyl methacrylate, dimethylaminomethyl methacrylate, dimethylaminomethyl methacrylate, dimethylaminomethyl methacrylate, 2-methyl_ Examples thereof include 5-vinylpyridine, morpholinomethyl methacrylate, morpholinoethyl methacrylate, vinylvinylpyrrolidone, and mixtures thereof.

When one or more monomers selected from the above (C-11) compounds and one or more monomers selected from the (C-12) compounds are copolymerized. The molar ratio between the (C-11) component and the (C-12) component is arbitrary, but in general, 80: 20 to 95: It is about 5. In addition, the reaction method of the copolymerization is also optional, but usually, the component (C-11) and the component (C-2) are subjected to radical solution polymerization in the presence of a polymerization initiator such as benzoyl peroxide. A copolymer can be easily obtained.

Specific examples of the component (C) include non-dispersible and dispersed polymethacrylates, non-dispersed and dispersed ethylene-monoolefin copolymers and hydrides thereof, polyisobutylene and hydrides thereof, and styrene-digen hydrogen. Copolymerized copolymer, styrene-maleic anhydride copolymer, polyalkylstyrene and the like.

In the present invention, the molecular weight of the component (C) is 40,000 or less, preferably 35,000 or less in terms of weight average molecular weight. If the weight average molecular weight exceeds 40,000, it is not preferable because the abrasion resistance after long-term use is poor. The weight average molecular weight of the component (C) is not particularly limited and may be 900 or more, but is preferably 10,000 or more, and more preferably 20,000 or more. (C) A viscosity index improver having a weight average molecular weight of less than 10,000 of the component, for example, polyisobutylene having a weight average molecular weight of 900 to less than 10,000 has a small effect of improving the viscosity index and needs to be blended in a large amount for a long time. Since it is difficult to maintain the anti-wear property after use, the weight average molecular weight of the component (C) is preferably 10,000 or more.

The component (C) in the present invention is particularly preferable because a non-dispersible polymethacrylate having a weight average molecular weight of 10,000 to 40,000 easily maintains abrasion resistance after long-term use.

The content of the component (C) in the lubricating oil composition of the present invention is desirably set so that the viscosity index of the composition is 160 or more, preferably 165 or more. On the other hand, it is desirable to set the content of the component (C) so that the upper limit of the viscosity index of the composition is preferably less than 210, more preferably less than 190. Moreover, kinematic viscosity of at 40 ° C of the composition, it is necessary to contain the amount of component (C) such that 20 to 30 mm ² / s, as preferably, as a 22~ 28 mm ² / s Is desirably contained. In the present invention, one or more arbitrarily selected from the viscosity index improvers as described above so that the viscosity index of the composition and the kinematic viscosity at 40 ° C. fall within the above specified ranges. For example, the content is 1% by mass or more, preferably 5% by mass or more, particularly preferably 6% by mass or more, and 20% by mass or less. Below, preferably 15% by mass or less, particularly preferably 12% by mass or less. If the viscosity index of the composition is less than 160, the abrasion resistance after long-term use deteriorates, which is not preferable.If the kinematic viscosity at 40 ° C is less than the above range, the initial and long-term If the kinematic viscosity at 40 ° C. exceeds the above range, the anti-wear property after use deteriorates, and it is difficult to obtain fuel economy due to reduced stirring resistance.

In the present invention, the component (A) is used as a base oil, the component (B) is blended in a specific amount, and the component (C) is added to the composition at a viscosity index of at least 160 and at a temperature of 40 ° C of the composition. By simply preparing a low-viscosity lubricating oil composition that has a kinematic viscosity of 20 to 3 O mms, a lubricating oil composition with excellent antiwear properties can be obtained even after initial and long-term use. As much power as possible, other types of additives may be added to enhance the performance. Such additives include antiwear agents or extreme pressure agents, metal detergents, friction modifiers, deterrent agents, corrosion inhibitors, pour point depressants, rubber swelling agents, antifoaming agents, coloring agents, etc. Can be mentioned. These compounds can be used alone or in combination of several kinds. Examples of the antiwear agent or extreme pressure agent that can be used in combination with the lubricating oil composition of the present invention include antiwear agents or extreme pressure agents for lubricating oils such as sulfur additives, phosphorus additives, sulfur and phosphorus additives. Ability to use any compound commonly used as an agent, for example, sulfur compounds such as disulphides, sulfides, sulfuric oils and fats, monophosphates, diesters, and triesters , Phosphite monoesters, phosphite diesters, phosphite triesters, phosphorus compounds such as salts of these esters with amines or alkanolamines, zinc dithiophosphate, thiophosphoric acid Sulfur and phosphorus compounds such as esters can be used. The content of these wear inhibitors or extreme pressure agents is not particularly limited, but is usually 0.01 to 5.0% by mass based on the total amount of the lubricating oil composition.

As the metal-based detergent that can be used in combination with the lubricating oil composition of the present invention, any compound that is commonly used as a metal-based detergent for lubricating oils can be used.For example, alkali metal or alkaline earth metal can be used. Sulfonates, phenates, salicylates, naphthenates and the like can be used alone or in combination of two or more in the composition of the present invention. Here, sodium potassium is exemplified as the alkali metal, and calcium, magnesium, etc. are exemplified as the alkaline earth metal. In addition, as a specific metal-based detergent, calcium or Gnesium sulfonates, phenates and salicylates are preferably used. The total base number and content of these metallic detergents can be arbitrarily selected according to the required lubricating oil performance, but the total base number is usually 0 to 500 mg KOH by the perchloric acid method. The content is 0.01 to 10% by mass.

As the friction modifier that can be used in combination with the lubricating oil composition of the present invention, any compound that is usually used as a friction modifier for lubricating oils can be used, and an alkyl group or alkenyl having 6 to 30 carbon atoms can be used. Examples thereof include amine compounds, fatty acid esters, fatty acid amides, and fatty acid metal salts having at least one group, particularly a straight-chain alkyl group or a straight-chain alkenyl group having 6 to 30 carbon atoms, in the molecule.

Examples of the amine compound include linear or branched, preferably linear, aliphatic monoamines having 6 to 30 carbon atoms, linear or branched, preferably linear, aliphatic polyamines, or these. Examples thereof include alkylene oxide adducts of aliphatic amines. Examples of the fatty acid ester include esters of a linear or branched, preferably linear, fatty acid having 7 to 31 carbon atoms with an aliphatic monohydric alcohol or an aliphatic polyhydric alcohol. Examples of the fatty acid amide include an amide of a linear or branched, preferably linear, fatty acid having 7 to 31 carbon atoms and an aliphatic monoamine or an aliphatic polyamine. Examples of the fatty acid metal salts include alkali earth metal salts (such as magnesium salts and calcium salts) and zinc salts of linear or branched, preferably linear, fatty acids having 7 to 31 carbon atoms. . In the present invention, one or more compounds arbitrarily selected from these friction modifiers can be contained in an arbitrary amount. It is desirably 0.01 to 5.0% by mass, preferably 0.03 to 3.0% by mass on the basis.

As the acid inhibitor which can be used in combination with the lubricating oil composition of the present invention, any compounds generally used in lubricating oils such as phenolic compounds and amine compounds can be used. Specifically, alkyl phenols such as 2-6-di-tert-butyl-4-methylphenol, and bisphenols such as methylene-1,4,4-bisphenol (2,6-di-tert-butyl-4-methylphenol) , Naphthylamines such as phenyl α-naphthylamine, dialkyldiphenylamines, zinc dialkyldithiophosphates such as zinc di-diethylhexyldithiophosphate, (3,5-di-tert-butyl) Fatty acid (such as propionic acid) and a monohydric or polyhydric alcohol, such as methanol, octanol, or octadecanol, 1,4-hydroxypheninole) or (3-methinole-5-tert-butyltinole-4-hydroxyphenyl) fatty acid Examples include esters with 6-hexadionole, neopentyl glycol, diethylene glycolonole, triethylene glycol, pentaerythritol, and the like.

One or more compounds arbitrarily selected from these can be contained in any amount, but usually the content is 0.01 to 0.1% based on the total amount of the lubricating oil composition. 5.0 mass. / ₀ is desirable.

As the corrosion inhibitor that can be used in combination with the lubricating oil composition of the present invention, any compound that is usually used as a corrosion inhibitor for lubricating oils can be used. Examples thereof include benzotriazole-based and tritritriazole-based compounds. Compounds, thiadiazole compounds, imidazole compounds and the like. One or two or more compounds arbitrarily selected from these can be contained in an arbitrary amount, but usually, the content is 0.01 to 0.1% based on the total amount of the lubricating oil composition. Desirably, the mass is ^3.0 / ₀ .

As the antifoaming agent that can be used in combination with the lubricating oil composition of the present invention, any compound that is usually used as an antifoaming agent for lubricating oils can be used. Is mentioned. One or more compounds arbitrarily selected from these can be contained in an arbitrary amount. Usually, the content is 0.001 to 1 based on the total amount of the lubricating oil composition. It is desirably 0.05% by mass. The lubricating oil composition of the present invention has excellent anti-wear properties even after initial and long-term use and can reduce agitation resistance caused by lubricating oil. Therefore, the lubricating oil composition for automobiles, for example, for internal combustion engines and transmissions, By using it for an automatic transmission or a continuously variable transmission, it will be possible to contribute to improving the fuel efficiency of automobiles.

Example

Hereinafter, the content of the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(Examples 1 to 5 and Comparative Examples 1 to 3)

Various lubricating base oils and additives shown in Table 1 or Table 2 were blended to form a lubricating oil thread (Examples 1 to 5 in Table 1) according to the present invention and a lubricating oil composition for comparison (Table 1). Comparative Examples 1 to 3) in Table 2 Prepared. The amount of each additive is based on the total amount of the composition.

For each of the obtained compositions, the anti-wear properties at the initial stage and after long-term use were evaluated by the abrasion test shown in the following (1). The new oil was used for the initial evaluation of wear resistance, and the deteriorated oil that had been deteriorated in advance by the ultrasonic shear test shown in (2) was used for the wear resistance evaluation of oil used for a long period. The results of the performance evaluation are also shown in Tables 1 and 2.

(1) Wear test

An LFW-1 friction test was performed under the following conditions in accordance with the test conditions specified in ASTM D 2714, and the wear width of the block test specimen after the test was measured. The smaller the wear width, the better the anti-wear properties.

(Test condition)

Ring: F a l e x S—10 Tes t R in g

(SAE 4620 S t e e l)

Block: F a l e x H— 30 Te st B l o c k

(SAE 01 S t e e l)

Test oil temperature 100 ° C

50 1 b

Sliding speed 100 c ra / s

(2) Ultrasonic shear test

An 8-hour shear test was performed according to the automatic transmission oil shear stability test method specified in J ASO M347-95. In this test, the degree of kinematic viscosity reduction in the process of using automatic transmission oil! The 8-hour shear test is equivalent to 100,000 km or more in actual running, and the oil after the completion of this test is considered to be equivalent to the oil after 100,000 km running.

〇

H- ¹

1) Refined mineral oil (100 ° C kinematic viscosity 2.0mm2 / s, viscosity index 95)

2) Refined mineral oil (kinematic viscosity at 100 ° C 4.4mm2 / s, viscosity index 95)

3) Polybutenyl succinimide (bis type, polybutenyl group number average molecular weight: 1,000, nitrogen content: 2.0% by mass)

4) Polybutenyl succinimide (bis type, polybutenyl group number average molecular weight: 1,300, nitrogen content: 1.6% by mass)

5) Boron-containing polybutenyl succinimide (bis type, polybutenyl group number average molecular weight: 2,500, nitrogen content

: 0.5 mass%, boron content: 0.25 mass! )

6) Non-dispersed polymethacrylate (weight average molecular weight 20,000)

7) Non-dispersed polymethacrylate (weight average molecular weight 30,000)

8) Non-dispersed polymethacrylate (weight average molecular weight 50,000)

9) Wear inhibitors, extreme pressure agents, metal detergents, corrosion inhibitors, antioxidants, friction modifiers, rubber swelling agents, defoamers

Including / package additives

〇 t

1) Refined base oil (kinematic viscosity at 100 ° C 2.0mm2 / s, number 95)

2) Refined base oil (Kinematic viscosity at 100 ° C 4.4mm2 / s, viscosity index 95)

3) Polybutenyl succinimide (bis-type, polybutenyl group number average molecular weight: 1,000, nitrogen content: 2.0% by mass)

5) Boron-containing polybutenyl succinimide (bis type, polybutenyl group number average molecular weight: 2,500, nitrogen content: 0.5% by mass, boron content: 0.25% by mass)

6) Non-dispersed polymethacrylate (weight average molecular weight 20,000)

7) Non-dispersed polymethacrylate (weight average molecular weight 30,000)

8) Non-dispersed polymethacrylate (weight average molecular weight 50,000)

9) Package additives including antiwear agents, extreme pressure agents, metal detergents, corrosion inhibitors, antioxidants, friction modifiers, rubber swelling agents, defoamers, etc.

When the compound was used as an essential component (Examples 4 and 5), the composition of Example 1 showed superior results in terms of antiwear properties even after initial and long-term use. Furthermore, when the succinic acid imid used in Example 1 and the boron-modified compound of succinimide used in Example 5 were used together (Example 4), the anti-wear performance was synergistically improved. Met. In contrast, when the content of the component (B) is less than the specified range of the present invention (Comparative Example 1), when the viscosity index of the composition is less than 160 (Comparative Example 2), When the weight-average molecular weight exceeds 40,000 (Comparative Example 3), the anti-wear property of the deteriorated oil is also poor when the fresh oil is used. When the kinematic viscosity at 40 ° C. of the composition was less than 20, the result was that the anti-wear property was even worse than that of the comparative example. Industrial applicability

The lubricating oil composition of the present invention has a low viscosity but has excellent anti-wear properties even after initial and long-term use, and can reduce agitation resistance caused by lubricating oil. By using it for transmissions, especially for automatic transmissions or continuously variable transmissions, it is possible to contribute to improving the fuel efficiency of vehicles. Also, lubricating oils for machinery and equipment other than automobiles can reduce the energy consumption of machinery and equipment while maintaining anti-wear properties, such as for wet brakes, hydraulic actuators, It is useful for various applications such as compressors, turbines, gears, refrigerators and bearings.

Claims

The scope of the claims

1. (A) Lubricating base oil consisting of mineral oil, synthetic oil, or a mixture thereof,

(B) A nitrogen-containing compound having at least one alkyl group or alkenyl group having a number average molecular weight of 900 or more and / or a derivative thereof is defined as a nitrogen content of 0-based on the total amount of the composition.

01 to 0.20 mass%, and

(C) A viscosity index improver having a weight average molecular weight of 40,000 or less is blended so that the composition has a viscosity index force of 160 or more and the composition has a kinematic viscosity at 40 ° C of ²⁰ to 30 mm ² Zs. A lubricating oil composition comprising:

2. The lubricating oil composition according to claim 1, wherein the component (B) is a nitrogen-containing compound having two alkyl groups or alkenyl groups having a number average molecular weight of 1200 or more and Z or a derivative thereof. object.

3. As the component (B), a boron-modified compound of a nitrogen-containing compound having at least one alkyl group or alkenyl group having a number average molecular weight of 900 or more is 0.002% by mass as the boron content based on the total amount of the composition. The lubricating oil composition according to claim 1 or 2, wherein the lubricating oil composition is contained as essential.

4. The lubricating oil according to claim 3, wherein the boron-modified compound is a boron-modified compound of a nitrogen-containing compound having at least one alkyl group or alkenyl group having a number average molecular weight of 1200 or more. Itoi components.

5. The lubricating oil composition according to claim 3, wherein the boron-modified compound is a boron-modified compound of a nitrogen-containing compound having two alkyl groups or alkenyl groups having a number average molecular weight of 1200 or more.

6. The lubricating oil composition according to claim 3, wherein the boron-modified compound is a boron-modified compound of a nitrogen-containing compound having two alkyl groups or alkenyl groups having a number average molecular weight of 1700 or more.

7. The lubricating oil composition according to any one of claims 3 to 6, wherein the boron-to-nitrogen mass ratio (BZN ratio) in the boron-modified compound is 0.01 to 3.

8. The component (B) according to claim 1, wherein the component (B) comprises a boron-modified compound of a bis-type succinimide having a poly (iso) butyr group having a number average molecular weight of 200 or more. Lubricating oil, composition.

9. The component (B) is a bis-type succinimide having a poly (iso) butenyl group having a number average molecular weight of 900 to less than 200, and a poly (iso) having a number average molecular weight of 200 or more. 2. The lubricating oil composition according to claim 1, wherein the lubricating oil composition is used in combination with a boron-modified bis-succinimide having a butyr group.

10. The lubricating oil composition according to any one of claims 1 to 9, wherein the composition is used for an automatic transmission or a continuously variable transmission.

11. Use of the lubricating oil composition according to claim 1 for an automatic transmission or a continuously variable transmission.

12. A method for maintaining wear resistance of an automatic transmission or a continuously variable transmission, characterized by using the lubricating oil composition according to any one of claims 1 to 9.