JP2000053991A - Lubricating oil composition for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having oxidation-resistant long service life at high temperatures and high fuel economy performance as well. SOLUTION: This lubricating oil composition is obtained by incorporating a mineral or synthetic oil as the base oil with a dynamic viscosity at 100 deg.C of 2-12 mm2/s and %CA of <=6 determined by ring analysis (n-d-m method) with (a) zinc dithiophosphate, (b) an oil-soluble sulfur-contg. molybdenum complex obtained by reaction of sulfur or thioacetamide with a molybdenum complex formed by reaction of molybdenum trioxide with a basic nitrogen compound selected from the group consisting of succinimide, carboxylic acid amides and Mannich base, and (c) at least one compound selected from molybdenum dithiocarbamate, molybdenum dithiophosphate and molybdic acid amine salts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil composition for an internal combustion engine, and more particularly, to a lubricating oil composition for a gasoline engine, which has a long oxidizing life under a high-temperature condition and has excellent properties. The present invention relates to a lubricating oil composition for internal combustion engines having low fuel consumption performance.

[0002]

2. Description of the Related Art In order to cope with energy and environmental problems, it is essential that lubricating oils for internal combustion engines have an effect of improving fuel efficiency. In recent years, long drainage is also necessary to cope with environmental problems. In addition to the required performance, lubricating oil for internal combustion engines is required to have high lubrication performance.

[0003] In view of the above background, friction modifiers such as organic molybdenum compounds are used in lubricating oils for internal combustion engines of automobiles and the like for the purpose of improving fuel economy. However, due to recent improvements in automobile technology, high power and high revolution of engines have been achieved, and since they are used under severe conditions, oxidative stability under high temperature conditions has been required.

Japanese Patent Publication No. 3-22438 discloses an engine oil in which the oxidation stability at high temperatures is improved by combining a sulfur-containing molybdenum complex with diphenylamine, but fails to provide a fuel efficiency improving effect. JP-A-6-313183 discloses a MoD.
It discloses an engine oil having a fuel efficiency improving effect and a high temperature oxidation stability by combining TP or MoDTC with an amine antioxidant, but both effects were insufficient.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above, and has an object to provide a lubricating oil composition for an internal combustion engine having a long oxidation life under high temperature conditions and excellent fuel economy. It is intended to provide.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have achieved the object of the present invention effectively by combining specific additives with highly refined base oil. It has been found that the present invention can be performed and the present invention has been completed. That is, the gist of the present invention is as follows. (1) a kinematic viscosity at 100 ° C. of ² to 12 mm ² / s,
Mineral oil or synthetic oil having a% CA of 6 or less by ring analysis (ndm method) is used as a base oil, and the base oil contains (a) zinc dithiophosphate, (b) succinimide, carboxylic acid amide and An oil-soluble sulfur-containing molybdenum complex obtained by reacting a molybdenum complex obtained by reacting a basic nitrogen compound selected from the group consisting of a Mannich base with molybdenum trioxide with sulfur or thioacetamide; and (c) A lubricating oil composition for an internal combustion engine, comprising at least one selected from molybdenum dithiocarbamate, molybdenum dithiophosphate and amine salts of molybdic acid. (2) The amount of phosphorus (P) derived from the component (a) is 0.02 to 0.15% by weight, and the amount of molybdenum (Mo) derived from the component (b) is 20 to 100 based on the total amount of the composition. Molybdenum (M) derived from the component (c).
o) The lubricating oil composition for an internal combustion engine according to (1), wherein the amount is 0.01 to 0.15% by weight.

[0007]

Embodiments of the present invention will be described below. First, in the present invention, as a base oil,
Mineral or synthetic oils are used, and it is essential that they have a kinematic viscosity at 100 ° C. of ² to 12 mm ² / s.
Preferably it is 3 to 8 mm ² / s. Kinematic viscosity is 2mm ²
If it is less than / s, evaporation loss is undesirably large. On the other hand, if it exceeds 12 mm ² / s, power loss due to viscous resistance increases, and a fuel efficiency improvement effect cannot be obtained, which is not preferable. Further, the% CA by ring analysis (ndm method) needs to be 6 or less. Preferably it is 2 or less. If it exceeds 6, the oxidative stability at high temperatures deteriorates.

As the mineral oil, for example, a distillate obtained by subjecting a paraffin-based crude oil, an intermediate-based crude oil or a naphthenic-based crude oil to atmospheric distillation, or a residual oil obtained by atmospheric distillation under reduced pressure, or Refined oils obtained by refining according to a conventional method, such as solvent-refined oils, hydrogenated refined oils, dewaxed oils, and clay-treated oils, can be mentioned. What is necessary is just to select the thing of a range.

On the other hand, synthetic oils include, for example, poly-α-olefin, α-olefin copolymer, polybutene, polyisobutylene, alkylbenzene, polyol ester, dibasic acid ester, polyoxyalkylene glycol, polyoxyalkylene glycol ester, polyoxyalkylene Glycol ether, trimellitic acid ester, hindered ester, silicone oil and the like can be mentioned. Among them, poly α-olefin (PAO) is preferred. These base oils can be used alone or in combination of two or more, and mineral oil and synthetic oil may be used in combination.

Next, the components (a) to (c) blended in the base oil will be described. (A ) Component Zinc dithiophosphate (hereinafter referred to as ZnDTP) is represented by the following general formula (I).

[0011]

Embedded image

In the general formula (I), R¹~ R^FourIs it
2-20 carbon atoms, which may be the same or different, preferably
Or 3-10 linear or branched alkyl groups.
You. Specifically, an ethyl group, an n-propyl group,
Pill group, n-butyl group, isobutyl group, sec-butyl
Group, tert-butyl group, various pentyl groups, various hexyl groups
Groups, various heptyl groups, various octyl groups, various nonyl groups
Groups, various decyl groups, various undecyl groups, various dodecyl groups,
Various tridecyl groups, various tetradecyl groups, various pentade
Sil group, various hexadecyl groups, various heptadecyl groups, each
Various octadecyl groups, various nonadecyl groups, various eicosyl
Groups. Note that R¹~ R ^FourIntroduce
In some cases, a mixture of α-olefins may be used as a raw material
However, in this case, as the component (a), an alkyl having a different structure is used.
It becomes a mixture of ZnDTP having a group.

The component (a) can be used alone or in combination of two or more.
Based on the total amount of the composition, the amount of phosphorus (P) is 0.02 to 0.
15% by weight. If the amount is less than 0.02% by weight, the effect of reducing friction and the effect of improving oxidation stability at high temperatures may not be sufficiently exhibited. If it exceeds 0.15% by weight,
In some cases, the improvement of the effect corresponding to the amount may not be recognized. More preferably, it is in the range of 0.05 to 0.10% by weight.

( B) Component A sulfur-containing molybdenum complex described in JP- B- 3-22438. That is, a molybdenum complex obtained by reacting molybdenum trioxide with a basic nitrogen compound selected from the group consisting of succinimide, carboxylic acid amide and Mannich base, and an oil solubility obtained by further reacting sulfur or thioacetamide. Is a sulfur-containing molybdenum complex.

The summary of the gist of Japanese Patent Publication No. 3-22438 is as follows. (1) As succinimide, a reaction product of polyisobutenyl succinic anhydride having 70 to 128 carbon atoms and a polyamine such as tetraethylenepentamine and triethylenetetramine is preferably used. (2) As the carboxylic acid amide, a fatty acid having 13 to 21 carbon atoms or a mixture of the fatty acid and a polyisobutenyl carboxylic acid having 72 to 128 carbon atoms in a polyisobutenyl group, and triethylenetetramine and tetraethylenepentamine Reaction products with polyamines such as are preferred. (3) As the Mannich base, phenol or C9
A reaction product of an alkyl-substituted phenol of from 200 to 200 with formaldehyde or paraformaldehyde and an alkylamine such as methylamine, or a polyamine such as diethylenetriamine or tetraethylenepentamine is preferably used.

(4) In the reaction between the basic nitrogen compound and molybdenum trioxide, water or ethylene glycol is preferably used as a catalyst, and a lubricating oil or a hydrocarbon solvent is suitably used as a diluent. (5) The reaction between the basic nitrogen compound and molybdenum trioxide is performed at a pressure around the atmospheric pressure between the melting point and the reflux temperature of the mixture. (6) The reaction product of a basic nitrogen compound and molybdenum trioxide generally contains 0.01 basic nitrogen compound per molybdenum trioxide.
２2 molybdenum atoms. (7) In the sulfur-containing molybdenum complex as the final product, 0.1 to 4 sulfur atoms are contained per one molybdenum atom.

The component (b) can be used alone or in combination of two or more.
Based on the total amount of the composition, the amount of molybdenum (Mo) is 20 to
100 ppm by weight. If it is less than 20 ppm by weight, the effect of improving oxidation stability at high temperatures may not be sufficiently exhibited. If it exceeds 100 ppm by weight, the effect may not be improved in proportion to the amount. More preferably, it is in the range of 40 to 80 ppm by weight.

The component ( c) is at least one selected from molybdenum dithiocarbamate (hereinafter referred to as MoDTC), molybdenum dithiophosphate (hereinafter referred to as MoDTP), and an amine salt of molybdic acid (hereinafter referred to as Mo amine salt). MoDT
C is represented by the following general formula (II).

[0019]

Embedded image

In the general formula (II), R ^{5 to} R ⁸ are hydrocarbon groups having ^{5 to} 16 carbon atoms, all of which may be the same or different. X is S (sulfur atom) or O (oxygen atom). Examples of the hydrocarbon group represented by R ^{5 to} R ⁸ include an alkyl group having 5 to 16 carbon atoms, an alkenyl group having 5 to 16 carbon atoms, a cycloalkyl group having 5 to 16 carbon atoms, and a And arylalkyl groups having 5 to 16 carbon atoms. Carbon number 5
Specific examples of the hydrocarbons of Nos. 16 to 16 include various pentyl groups,
Various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various undecyl groups, various dodecyl groups, various tridecyl groups, various tetradecyl groups, various pentadecyl groups, various hexadecyl groups, various octenyl groups, various nonenyl groups Groups, various decenyl groups, various undecenyl groups, various dodecenyl groups, various tridecenyl groups, various tetradecenyl groups, various pentadecenyl groups, cyclohexyl groups, dimethylcyclohexyl groups, ethylcyclohexyl groups, methylcyclohexylmethyl groups, cyclohexylethyl groups, propylcyclohexyl groups, Butylcyclohexyl group, heptylcyclohexyl group, phenyl group,
Examples thereof include a tolyl group, a dimethylphenyl group, a butylphenyl group, a nonylphenyl group, a methylbenzyl group, a phenylethyl group, a naphthyl group, and a dimethylnaphthyl group. MoDTP is represented by the following general formula (III).

[0021]

Embedded image

In the general formula (III), R ^{9 to} R ¹² are hydrocarbon groups having 5 to 16 carbon atoms, all of which may be the same or different. Y is S (sulfur atom) or O (oxygen atom). Examples of the hydrocarbon group represented by R ^{9 to} R ¹² include an alkyl group having 5 to 16 carbon atoms, an alkenyl group having 5 to 16 carbon atoms, a cycloalkyl group having 5 to 16 carbon atoms, and a And arylalkyl groups having 5 to 16 carbon atoms. Carbon number 5
Specific examples of the hydrocarbons of Nos. 16 to 16 include various pentyl groups,
Various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various undecyl groups, various dodecyl groups, various tridecyl groups, various tetradecyl groups, various pentadecyl groups, various hexadecyl groups, various octenyl groups, various nonenyl groups Groups, various decenyl groups, various undecenyl groups, various dodecenyl groups, various tridecenyl groups, various tetradecenyl groups, various pentadecenyl groups, cyclohexyl groups, dimethylcyclohexyl groups, ethylcyclohexyl groups, methylcyclohexylmethyl groups, cyclohexylethyl groups, propylcyclohexyl groups, Butylcyclohexyl group, heptylcyclohexyl group, phenyl group,
Examples thereof include a tolyl group, a dimethylphenyl group, a butylphenyl group, a nonylphenyl group, a methylbenzyl group, a phenylethyl group, a naphthyl group, and a dimethylnaphthyl group. Mo amine salt is a secondary amine salt of molybdic acid represented by the following general formula (IV).

[0023]

Embedded image

In the general formula (IV), R represents 5-1 carbon atoms.
8 hydrocarbon groups, and even if the four hydrocarbon groups are the same,
It may be different. As the hydrocarbon group having 5 to 18 carbon atoms, for example, an alkyl group having 5 to 18 carbon atoms,
Alkenyl group having 5 to 18 carbon atoms, cycloalkyl group having 5 to 18 carbon atoms, alkylaryl group having 5 to 18 carbon atoms, 5 carbon atoms
To 18 arylalkyl groups. Specific examples of hydrocarbons having 5 to 18 carbon atoms include various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various undecyl groups, various dodecyl groups, various tridecyl groups, Various tetradecyl groups, various pentadecyl groups, various hexadecyl groups,
Various heptadecyl groups, various octadecyl groups, various octenyl groups, various nonenyl groups, various decenyl groups, various undecenyl groups, various dodecenyl groups, various tridecenyl groups, various tetradecenyl groups, various pentadecenyl groups, cyclohexyl groups, dimethylcyclohexyl groups, ethylcyclohexyl groups , Methylcyclohexylmethyl, cyclohexylethyl, propylcyclohexyl, butylcyclohexyl, heptylcyclohexyl, phenyl, tolyl, dimethylphenyl, butylphenyl, nonylphenyl, methylbenzyl, phenylethyl, naphthyl , Dimethylnaphthyl group and the like.

Among the above components (c), Mo is effective in terms of effect.
DTC is preferred. The component (c) can be used singly or in combination of two or more kinds. A preferable compounding amount thereof is 0.01 to 0.15% by weight as a molybdenum (Mo) amount based on the total amount of the composition. If the amount is less than 0.01% by weight, the effect of reducing friction and the effect of improving oxidation stability at high temperatures may not be sufficiently exhibited. If it exceeds 0.15% by weight, no improvement in the effect corresponding to the amount is observed. More preferably, it is in the range of 0.03 to 0.10% by weight.

Further, the lubricating oil composition of the present invention usually contains various additives conventionally used in lubricating oils, for example, in order to improve the physical properties of the lubricating oil within a range that does not impair the object of the present invention. Metal-based detergents such as sulfonates, phenates and salicylates of alkaline earth metals; ashless dispersants such as succinimides and succinates; antioxidants such as phenols, amines and sulfurs; disulfides; Extreme pressure agents, friction modifiers such as polyhydric alcohol partial esters, amines and amides, viscosity index improvers such as polymethacrylates and olefin copolymers, chlorinated paraffin-naphthalene condensates, polymethacrylates, polyacrylates and polyalkylstyrenes Pour point depressants, metal deactivators such as benzotriazole and thiadiazole, alkenyl succinic acid and its parts Rust inhibitors such as esters, polyalkylene ethers, polyalkylene alkyl phenyl ethers, defoamers such as silicone oil, etc., based on the total amount of the composition, are 3 to 3 in total of additives other than the components (a) to (c). 1
It can be blended in the range of 0% by weight.

[0027]

Next, the present invention will be described in more detail with reference to examples.
As will be explained, the present invention is in no way limited by these examples.
Not something. Examples 1 to 9 and Comparative Examples 1 to 4 The following additives are shown in Tables 1 and 2 in the following base oils.
The lubricating oil compositions of the examples and the comparative examples were obtained by mixing at a ratio.
The lubricating oil composition is oxidized at high temperature by the method shown below.
The stability and coefficient of friction were evaluated and the results are shown in Table 1.
(Example) and Table 2 (Comparative Example). (1) Base oil PAO (Hydride of 1-decene dimer: 100 ° C
Kinematic viscosity at 6.0mm ^Two/ S,% CA = 0, Example
1) Mineral oil 1 (paraffinic mineral oil: kinematic viscosity at 100 ° C)
4.2mm^Two/ S,% CA = 0, Examples 2, 4 to 9, ratio
Comparative Examples 2 to 4) Mineral oil 2 (paraffinic mineral oil: kinematic viscosity at 100 ° C.)
4.3mm^Two/ S,% CA = 5.0, Example 3) Mineral oil 3 (paraffinic mineral oil: kinematic viscosity at 100 ° C.)
4.1mm^Two/ S,% CA = 7.6, Comparative Example 1)

(2) Additive (a) Ingredient: ZnDTP (Zn content: 9.0% by weight, P content: 7.8% by weight, S content: 15.0% by weight, alkyl group is secondary and has 3 carbon atoms and Examples 1 to 9 and Comparative Examples 1 to 3 having a carbon number of 6 and a primary one having 8 carbon atoms. (B) Component-Sulfur-containing Mo complex (Example 1 of Japanese Patent Publication No. 3-22438) Mo content: 6.3% by weight, S content: 2.2% by weight, Examples 1 to 9, Comparative examples 1, 3, 4) (c) Component MoDTC (Mo content: 4.5% by weight) , S content: 5.7% by weight, alkyl group having 8,13 carbon atoms, Examples 1 to 7, Comparative examples 1, 2, 4) MoDTP (Mo content: 9.0% by weight, P content: 3.3% by weight) , S content 9.9% by weight, alkyl group having 8 carbon atoms, Example 8) Mo amine salt (Mo content 4.5% by weight, Example 9)

(3) Evaluation method (i) Coefficient of friction (μ) Using a block-on-ring tester (LFW-1), rotation speed 1,400 rpm, load 20 lbs, oil temperature 80 ° C., time 15 minutes, half of the ring is a sample A load is applied to the block using a Falex H-60 test block as the test block and a Falex S-10 test ring as the test ring, and the resistance generated when the ring is rotated is distorted. The friction coefficient was calculated. (Ii) High-temperature oxidation stability The oxidation induction time (min) was measured under the following evaluation conditions in accordance with ASTM D-4742 (TFOUT). (Evaluation conditions) Test temperature: 160 ° C, oxygen pressure: 620 kPa, sample oil:
1.5 g, catalyst: SRM1817c, water amount: 2% by weight based on sample oil, fuel catalyst amount: 4% by weight based on sample oil, metal catalyst amount: 4% by weight based on sample oil

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

[0033]

[Table 4]

[0034]

The lubricating oil composition for an internal combustion engine according to the present invention has a long oxidizing life under high temperature conditions and has excellent fuel efficiency, and is particularly practical as an engine oil. .

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10N 20:02 30:08 30:10 40:25 (72) Inventor Masahiko Kido 24 Anesaki Kaigan, Ichihara-shi, Chiba Address 4 F term (reference) 4H104 AA13R AA18R AA20C BE02C BE11C BE11R BG07R BG10C BH04R BJ07C DA03A DB01C DB03R EA02A EA21C EB02 FA02 FA06 LA04 LA05 PA41

Claims (2)

[Claims] A kinematic viscosity at 100 ° C. of 2 to 12 mm
² / s, a mineral oil or a synthetic oil having a% CA of 6 or less as determined by ring analysis (ndm method) as a base oil, wherein (a) zinc dithiophosphate, (b) succinimide, Molybdenum complex obtained by reacting a basic nitrogen compound selected from the group consisting of a carboxylic acid amide and a Mannich base with molybdenum trioxide, an oil-soluble sulfur-containing molybdenum complex obtained by further reacting sulfur or thioacetamide,
And (c) a lubricating oil composition for an internal combustion engine, comprising at least one selected from molybdenum dithiocarbamate, molybdenum dithiophosphate and an amine salt of molybdic acid. 2. The amount of phosphorus (P) derived from the component (a) is 0.02 to 0.15% by weight, based on the total amount of the composition.
(B) The amount of molybdenum (Mo) derived from the component is 20 to 1
The lubricating oil composition for an internal combustion engine according to claim 1, wherein the amount of molybdenum (Mo) derived from the component (c) is 0.01 to 0.15% by weight.