JP2006199857A - Gasoline engine oil composition excellent in low fuel expense - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gasoline engine oil capable of widely reducing the exhaust amount of carbon dioxide from an automobile by a different approach from preceding technologies and excellent in low fuel expense. <P>SOLUTION: This gasoline engine oil is provided by blending at least a salicylate-based cleaner and an ash-less friction regulator, and contains as a base oil component, the base oil showing ≤95 nm oil membrane thickness measured under the conditions of 4.4 m/s sliding velocity, 0.53 GPa hertz pressure and 100°C oil temperature. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gasoline engine oil composition having excellent fuel efficiency.

  Japan's oil demand is about 250 million kiloliters annually, of which about 40% is consumed as fuel for automobiles such as gasoline and light oil, and about 20% of Japan's total carbon dioxide emissions are in the transportation sector. The amount of emissions is increasing year by year. At the Global Warming Prevention Conference held in Kyoto in December 1997, it was discussed to reduce carbon dioxide emissions, and Japan's reduction target was agreed to be 6% lower than carbon dioxide emissions in 1990 It was done. Against this background, the transportation sector is obliged to improve fuel efficiency by about 20% compared to 1995 by 2010, and the most important is to reduce carbon dioxide emissions from automobiles by further reducing fuel consumption of gasoline and diesel internal combustion engines. It is a difficult issue.

  There are many methods to reduce carbon dioxide emissions from automobiles, that is, to improve fuel efficiency, such as improving engine combustion efficiency and reducing the weight of the vehicle body and engine. Friction reduction is the least social cost burden. In particular, the response method using engine oil does not require changes in engine design or the like, unlike improvement in combustion efficiency, and can be applied easily and in a wide range.

  Most of the prior art used in conventional fuel-saving gasoline engine oils is achieved by the addition of friction modifiers, particularly organic molybdenum friction modifiers, and the use of high viscosity index base oils. Although there exists patent documents 1-6 as a prior art which mix | blends an organomolybdenum type | system | group friction modifier, we are anxious about the point that an organic molybdenum type | system | group friction modifier is expensive.

  Further, Non-Patent Document 1 is given as a typical prior art that focuses on the characteristics of the base oil of gasoline engine oil and solves the above problems using a base oil having a large viscosity index.

JP 2001-348591 A Japanese Patent Laid-Open No. 2002-12884 JP 2002-371292 A JP 2001-181664 A JP-A-8-302378 Japanese Patent Laid-Open No. 9-3463 SAE TECHNICICAL PAPER 951036

  An object of the present invention is to provide a gasoline engine oil composition that can significantly reduce carbon dioxide emission from an automobile by an approach different from each of the above-described prior arts and is excellent in fuel efficiency.

  The inventors of the present invention have paid attention to the characteristics of the base oil used in gasoline engine oil, and as a result of intensive research, the gasoline engine oil composition containing a salicylate-based detergent and an ashless friction modifier contains a base oil. As one of the components, when a base oil having an oil film thickness of 95 nm or less measured under specific conditions is contained in an amount of 5% by mass or more of the base oil component, it has been surprisingly found that low fuel consumption can be achieved. It has come to be completed.

A first aspect of the present invention is a gasoline engine oil composition in which at least a salicylate detergent and an ashless friction modifier are blended with a base oil, and a slip speed of 4.4 m / s and a Hertz pressure of 0 are used as base oil components. The present invention relates to a gasoline engine oil composition characterized by containing a base oil having an oil film thickness of 95 nm or less, preferably 80 nm or less, particularly preferably 70 nm or less measured under the conditions of .53 GPa and an oil temperature of 100 ° C.
The method for measuring the oil film thickness of the present invention is specifically the method described in FIG. 1 of the document SAE TECHNIC PAPA 961142.
In the second aspect of the present invention, the base oil having an oil film thickness of 95 nm or less measured under conditions of a sliding speed of 4.4 m / s, a Hertz pressure of 0.53 GPa, and an oil temperature of 100 ° C. is 5% by mass in the total base oil. The present invention relates to a gasoline engine oil composition according to claim 1, which preferably accounts for 7% by mass or more, particularly preferably 9% by mass or more.
In the third aspect of the present invention, the addition amount of the salicylate detergent is 0.5 to 10.0% by mass, preferably 1.0 to 8.0% by mass, more preferably 1.0 to 5.0% by mass, The addition amount of the ashless friction modifier is 0.01 to 5.0% by mass, preferably 0.05 to 2.5% by mass, more preferably 0.5 to 2.5% by mass. 2. The gasoline engine oil composition according to 2.
The fourth aspect of the present invention relates to the gasoline engine oil composition according to claim 1 or 2, wherein the ashless friction modifier is a compound containing an oleyl group.

  Increasing the amount of the salicylate detergent is effective in improving the cleanliness and oxidation stability, while the compounding amount exceeding 10.0% by mass reduces the effect of addition with respect to cost increase. Further, since a large amount of addition leads to an increase in ash content in the lubricating oil and causes an increase in the amount of piston deposit produced, 10.0% by mass or less is practical and preferable. Moreover, since an effect is not expectable if it is less than 0.5 mass%, 0.5 mass% or more is preferable.

  The salicylate detergent used in the present invention is particularly preferably calcium alkylbenzene salicylate, and the periodic table between the aromatic carboxylic acids which are compounds shown in Japanese Patent Nos. 1271,215 and 1031507 and atomic numbers 12 to 56 is used. An oil-soluble basic salt with a Group II metal and a lubricant having a total alkali number of 12 mgKOH / g or more. However, in the present invention, the alkyl salicylate metal salt compound is preferably a calcium salt or a magnesium salt. This is because, in the case of alkyl salicylate beryllium salt and barium salt, a water-soluble salt may be generated by the reaction of moisture caused by combustion of the internal combustion engine and weak acid formed by oxidative degradation of the lubricating oil. May be environmentally unfavorable in terms of biotoxicity. In the case of beryllium salt, the crystal hardness of beryllium carbonate produced by the reaction with carbon dioxide gas is high, so there is a concern that the wear resistance is deteriorated. For other metals, the cost of the metal is high and it is difficult to put it to practical use. The salicylate detergent in the present invention preferably has a total alkali number of 50 to 400 mgKOH / g as a gasoline engine oil composition imparting the lubricity of the present invention.

  While increasing the amount of the ashless friction modifier is effective for improving fuel efficiency, the addition of more than 5.0% by mass reduces the effect of adding to the cost increase, so 5.0% by mass or less is a reality. Is. Moreover, since an effect cannot be anticipated if it is less than 0.01 mass%, 0.01 mass% or more is preferable. Ashless friction modifiers such as alkyl carboxylic acids, alkyl carboxylic acid esters, alkyl amines, alkyl amides, and alkyl ethers have a greater effect of reducing friction as the alkyl group length increases. However, as the alkyl chain length increases, lubricating oil Solubility decreases. The oleyl group has an alkyl group length sufficient to exert a friction reducing action, and also contains an unsaturated bond in the molecule, and has an oleyl group and has an ashless friction control. The agent has higher solubility in lubricating oil than other ashless friction modifiers. Therefore, it is more advantageous than other ashless friction modifiers for the friction reduction effect.

  As the base oil used in the present invention, mineral oil-based lubricating oil, synthetic oil-based lubricating oil, or a mixture of two or more selected from these can be used. The same applies to the base oil that satisfies the conditions of the oil film thickness measured below. For example, mineral oil-based lubricating oil, mixed oil of mineral oil-based lubricating oil and non-aromatic synthetic oil-based lubricating oil, mixing of aromatic-containing synthetic oil and non-aromatic-containing synthetic oil-based lubricating oil An oil etc. can be illustrated.

  In general, engine oils contain base oils, detergents and friction modifiers, as well as antiwear agents, ashless dispersants, antioxidants, viscosity index improvers, pour point depressants, antifoaming agents, etc. However, an appropriate amount of these various additives can be added to the lubricating composition of the present invention as desired.

  As the antiwear agent, zinc dithiophosphate (ZnDTP) is generally blended, but in the present invention, it has an alkyl group having 3 to 12 carbon atoms, and the alcohol residue thereof is secondary (Sec-ZnDTP) or Primary (Pri-ZnDTP) or a mixture thereof is preferably blended, and the addition amount is preferably 0.03 to 0.1% by mass in terms of elemental phosphorus, and especially in terms of elemental phosphorus. 0.03-0.08 mass% is the most preferable.

  As the ashless dispersant, it is usually blended at a ratio of 2 to 10% by mass, and the types thereof include polyalkenyl succinimides shown in Japanese Patent Nos. 1367796, 1667140, 1302811, and 1743435, Examples thereof include polyalkenyl succinic acid esters, and boronated derivatives of these compounds can be blended in the gasoline engine oil composition imparting the lubricity of the present invention.

  Antioxidants include 2-t-butylphenol, 2-t-butyl-4-methylphenol, 2-t-butyl-5-methylphenol, 2,4-di-t-butylphenol, 2,4-dimethyl- 6-t-butylphenol, 2-t-butyl-4-methoxyphenol, 3-t-butyl-4-methoxyphenol, 2,6-di-t-butylphenol, 2,6-di-t-butyl-4- Methylphenol, 2,6-di-t-butyl-4-ethylphenol, 2,6-di-t-butyl-4-methoxyphenol, 2,6-di-t-butyl-4-ethoxyphenol, 3, 5-di-tert-butyl-4-hydroxybenzylmercapto-octyl acetate, n-dodecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2 -Ethylhexyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,6-di-t-butyl-α-dimethylamino-p-cresol, 4,4'-methylenebis (2 , 6-di-t-butylphenol), 4,4'-bis (2,6-di-t-butylphenol), 2,2-bis (3,5-di-t-butyl-4-hydroxyphenyl) propane 4,4'-cyclohexylidenebis (2,6-t-butylphenol), hexamethylene glycol bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (Ciba Specialty) * Chemicals: Irganox L109), 2,2'-thio- [diethyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] Ciba Specialty Chemicals: Irganox L115), tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane (Ciba Specialty Chemicals: Irganox L101) ), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene (manufactured by Shell Japan: Ionox 330), bis- [3,3 '-Bis- (4'-hydroxy-3'-t-butylphenyl) butyric acid] glycol ester, 2- (3', 5'-di-t-butyl-4-hydroxyphenyl) methyl-4- ( 2 ″, 4 ″ -di-tert-butyl-3 ″ -hydroxyphenyl) methyl-6-tert-butylphenol, 2,6-bis (2 -Hydroxy-3'-t-butyl-5'-methyl-benzyl) -4-methylphenol and other phenolic antioxidants, p, p'-dioctyl-diphenylamine, p, p'-di-α-methylbenzyl -Diphenylamine, Np-butylphenyl-Np'-octylphenylamine, mono-t-butyldiphenylamine, monooctyldiphenylamine, di (2,4-diethylphenyl) amine, di (2-ethyl-4-nonyl) Phenyl) amine, octylphenyl-1-naphthylamine, Nt-dodecylphenyl-1-naphthylamine, 1-naphthylamine, phenyl-1-naphthylamine, phenyl-2-naphthylamine, N-hexylphenyl-2-naphthylamine, N-octyl Phenyl-2-naphthylamine, N, N'-diiso Examples include amine-based antioxidants such as propyl-p-phenylenediamine and N, N′-diphenyl-p-phenylenediamine, and organic molybdenum compounds such as molybdenum dithiocarbamate and molybdenum alkylamine salts. Several types can be used in combination at 0.01 to 5% by mass, preferably 0.1 to 3% by mass.

  Examples of the viscosity index improver include styrene-butadiene copolymers and styrene-isoprene star copolymers described in Japanese Patent Nos. 954077, 1031507, 1468752, 1764494, and 1751082. , Polymethacrylates, ethylene-propylene copolymers and the like, and these are used in a proportion of 1 to 20% by mass. Further, a dispersion type viscosity index improver obtained by copolymerizing a polar monomer containing a nitrogen atom or an oxygen atom in the molecule can be used in the same manner.

  As the pour point depressant, methacrylate polymers described in Japanese Patent Nos. 1195542 and 1264056 are used. As the rust inhibitor, alkenyl succinic acid or a partial ester thereof, benzotriazole compound, thiadiazole compound, and the like are used.

  As the antifoaming agent, dimethylpolycyclohexane, polyacrylate or the like is used.

  In order to further clarify the features of the present invention, a comparison between a fuel-efficient gasoline engine oil composition that is currently widely used in the field and a gasoline engine oil composition that is an example of the present invention is as shown in Table 1 below. become.

(1) A gasoline engine oil composition having excellent fuel efficiency can be provided by the present invention.
(2) The present invention pays attention to the characteristics of the base oil, which is a basic component of the lubricating oil, and has found a lubricating oil composition having excellent fuel efficiency by combining with a specific additive composition.
(3) The present invention can sufficiently achieve the object without using a non-ashless friction reducing agent such as an organic molybdenum compound.

  Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited thereto.

The evaluation test methods employed in the present invention are as follows.
The oil film thickness of the base oil was measured by the method described in the document SAE TECHNICICAL PAPER 961142 (the method of FIG. 1 in the document). The 100 ° C. high temperature high shear viscosity was determined by ASTM D5481 test method.
The kinematic viscosity at 100 ° C. and 40 ° C. was determined by the JIS K2283 test method.
The viscosity index was determined by the JIS K2283 test method.
Evaluation of low fuel consumption FIG. 1 shows an outline of an engine torque loss test apparatus for evaluating low fuel consumption. By using a 3.0L engine with a direct-acting valve mechanism, controlling the engine speed from an idle speed to 2800 rpm with an electric motor at an engine oil temperature of 80 ° C, and measuring the generated friction loss torque, the engine The friction characteristics of the oil were evaluated.
The results show how much the engine loss torque at each engine speed was improved as compared with Comparative Example 1 as the engine loss torque improvement rate.

  Table 2 shows the properties of the base oils used in the examples and comparative examples of the present invention, Table 3 shows the compositions of the examples and comparative examples of the present invention, and Table 4 shows the results of the low fuel consumption test. Since Table 4 shows the degree of improvement of each Example and Comparative Example with respect to Comparative Example 1, the data of Comparative Example 1 in Table 4 is exactly 0.

表中の５Ｗ−３０および０Ｗ−３０はＳＥＡエンジン油の粘度分類におけるＳＥＡエンジン粘度番号である。
アイドルとは、軸出力を出さず、エンジンの機械損失に打ち克って設定回転数を維持している状態をいう。

5W-30 and 0W-30 in the table are SEA engine viscosity numbers in the viscosity classification of SEA engine oil.
Idle means a state in which the set rotational speed is maintained without overcoming the mechanical loss of the engine without producing shaft output.

The calcium salicylate in Table 3 is Infineum M7101 obtained from Infinium Japan, and the calcium sulfonate is Lz52 obtained from Nippon Lubrizol.
The ashless friction modifier in Table 3 is oleic acid ester Emazole MO-50 obtained from Kao Corporation.
The viscosity index improver in Table 3 is polymethacrylate Viscoplex 6-950 obtained from Degussa Japan, and the ashless dispersant is polyalkenyl succinimide Infineum M7107 obtained from Infinium Japan, wear-resistant Agent (ZnDTP) was obtained from Nippon Lubrizol, Lz1395, the antioxidant was a phenolic antioxidant Irganox L135 obtained from Ciba Specialty Chemicals, and the pour point depressant was obtained from Infinium Japan. Polymethacrylate Infineum V351, the antifoaming agent, is dimethylpolycyclohexane obtained from Dow Corning.

FIG. 1 is a schematic diagram of an engine torque loss test apparatus used for evaluating low fuel consumption.

Claims (4)

  A gasoline engine oil composition in which at least a salicylate-based detergent and an ashless friction modifier are blended with a base oil, a sliding speed of 4.4 m / s, a Hertz pressure of 0.53 GPa, and an oil temperature of 100 ° C. as a base oil component A gasoline engine oil composition comprising a base oil having an oil film thickness of 95 nm or less measured under the above conditions.   The base oil having an oil film thickness of 95 nm or less measured under conditions of a sliding speed of 4.4 m / s, a Hertz pressure of 0.53 GPa, and an oil temperature of 100 ° C. occupies 5% by mass or more of the total base oil. Item 4. A gasoline engine oil composition according to Item 1.   The gasoline engine oil composition according to claim 1 or 2, wherein the addition amount of the salicylate detergent is 0.5 to 10.0 mass% and the addition amount of the ashless friction modifier is 0.01 to 5.0 mass%. object. The gasoline engine oil composition according to claim 1 or 2, wherein the ashless friction modifier is a compound containing an oleyl group.

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