JP2011201962A - Fuel-saving engine oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel-saving engine oil excellent in corrosion and abrasion preventive performance.SOLUTION: A fuel-saving engine oil composition includes: an organic molybdenum compound in an amount of not less than 0.02 mass% in terms of the amount of molybdenum (Mo); not less than 0.03 mass% of benzotriazole or a benzotriazole derivative; and not less than 0.1 mass% of diphenyl carbodiimide or a bis(alkylphenyl) carbodiimide compound in a mineral oil-based and/or synthetic oil-based lubricating base oil. Preferably, molybdenum dithiocarbamate (MoDTC) as the organic molybdenum compound and the lubricating base oil having kinematic viscosity at 100°C of 4.5 mm/s or less as the lubricating base oil are used.

Description

  The present invention relates to a fuel-saving engine oil excellent in corrosion and wear prevention performance.

In recent years, there has been an increasing demand for improving the fuel efficiency of automobiles and suppressing CO ₂ emissions to prevent global warming. While improving engine efficiency is important for improving automobile fuel efficiency, reducing engine friction can also contribute to improving fuel efficiency. Therefore, the use of low-friction materials for sliding parts and fuel-saving engine oil Adopted.

  Fuel-saving engine oils include low viscosity of 5W-30 and 0W-30 in the viscosity classification stipulated by SAE (American Automotive Engineers) J300, and additives that reduce friction (friction modifiers, hereinafter FM It is known that it is effective to mix organic molybdenum FM such as molybdenum dithiocarbamate (MoDTC).

  However, it is known that sulfuric acid is generated from the sulfur content in fuel and engine oil, and a part of the generated sulfuric acid is contained in the engine oil, which corrodes and wears engine members. Therefore, there is a strong demand for engine oils that are excellent in corrosion resistance even when blended with MoDTC.

  As a lubricating oil composition for internal combustion engines with improved corrosion prevention and wear reduction, lubricating base oil, sulfurized oxymolybdenum dithiocarbamate, acid amide compound, fatty acid partial ester compound and / or aliphatic amine compound, and benzotriazole The thing containing a derivative | guide_body is proposed (patent document 1). However, this lubricating oil composition is not yet sufficient for preventing corrosion and reducing wear.

JP 2008-106199 A

  An object of the present invention is to provide an engine oil excellent in corrosion, wear prevention performance, and fuel efficiency.

  As a result of diligent research on various lubricating oil base materials and lubricating oil additives that constitute engine oils, the present inventor has benzotriazole or benzotriazole derivatives and diphenyl as lubricating oil additives. The inventors found that an engine oil containing a specific amount of a carbodiimide or bis (alkylated phenyl) carbodiimide compound and an organomolybdenum compound is excellent in fuel efficiency and exhibits excellent corrosion and wear prevention performance. .

That is, the present invention for solving the problems includes a mineral base oil and / or a synthetic base oil, and an organic molybdenum compound in an amount of molybdenum (Mo) of 0.02% by mass or more, benzotriazole or a benzotriazole derivative. Is a fuel-saving engine oil composition characterized by containing 0.03% by mass or more and 0.1% by mass or more of a diphenylcarbodiimide or bis (alkylated phenyl) carbodiimide compound.
In the present invention, preferably, the organic molybdenum compound is molybdenum dithiocarbamate (MoDTC), and the lubricating base oil has a kinematic viscosity at 100 ° C. of 4.5 mm ² / s or less. is there.

  The fuel-saving engine oil composition of the present invention is excellent in fuel efficiency especially in a high temperature region because it has little corrosion and wear of engine members even after long-term use and is excellent in low friction characteristics. .

  As the lubricating base oil used in the fuel-saving engine oil composition of the present invention, any of mineral oil, synthetic oil, and mixtures thereof can be used. As mineral oil, a high viscosity index lubricating base oil having a viscosity index of 120 or more is preferable. A high viscosity index lubricating base oil having a viscosity index of 120 or more can be obtained by solvent dewaxing or hydrodewaxing a product oil obtained by hydroisomerization of wax or hydrocracking of heavy oil. .

The hydroisomerization of wax is from wax having a boiling range of 300 to 600 ° C. and a carbon number of 20 to 70, such as slack wax obtained in a solvent dewaxing step of mineral oil-based lubricating oil, hydrocarbon gas, etc. Using a wax obtained by Fischer-Tropsch synthesis for synthesizing a liquid fuel as a raw material, a hydroisomerization catalyst, for example, a group 8 metal such as nickel and cobalt on an alumina or silica-alumina carrier, and 6A such as molybdenum and tungsten. A catalyst supporting one or more of group metals, a zeolite catalyst, or a catalyst supporting platinum or the like on a zeolite-containing support, a temperature of 300 to 450 ° C. in the presence of hydrogen at a hydrogen partial pressure of 5 to 14 MPa, 0.1 to 0.1 This can be done by contacting at 2 h ^-1 LHSV (liquid space velocity). At this time, it is preferable that the conversion rate of the linear paraffin is 80% or more and the conversion rate to the light fraction is 40% or less.

On the other hand, the lubricating base oil having a high viscosity index used in the present invention through hydrocracking of heavy oil can be obtained as follows. If necessary, hydrodesulfurization and denitrogenation, normal pressure distillate, vacuum distillate or bright stock having a boiling point in the range of 300 to 600 ° C., nickel, cobalt on hydrocracking catalyst such as silica-alumina support A catalyst supporting one or more group 8 metals such as molybdenum and tungsten, and a catalyst having a hydrogen partial pressure of 7 to 14 MPa in the presence of hydrogen at a temperature of 350 to 450 ° C., 0.1 It can be carried out by contact at LHSV (liquid space velocity) of ˜2h ⁻¹ , and the decomposition rate (the reduced mass% of the fraction of 360 ° C. or more in the product) should be 40 to 90%. Is preferred.

Lubricating oil fraction can be obtained by distilling off the light fraction from the hydroisomerized product oil or hydrocracked product oil obtained by the above method, but this fraction generally has a high pour point and viscosity. and the viscosity index is not high enough, perform dewaxing treatment, to remove the wax fraction, n-d-M ring analysis% C _P is 80 or more, a pour point viscosity index at -10 ° C. or less More than 120 lubricating base oils can be obtained.

  When removing the wax by solvent dewaxing, the light fraction is distilled off using a precision distillation apparatus, and the fraction having a boiling point of 371 ° C. or higher and lower than 491 ° C. by gas chromatography distillation is previously used. Is preferably 70% by mass or more in order to perform the solvent dewaxing process more efficiently. In this solvent dewaxing treatment, for example, methyl ethyl ketone / toluene (volume ratio 1/1) is used as a dewaxing solvent, and the solvent / oil ratio is in the range of 2/1 to 4/1. It is good to do.

On the other hand, when the wax content is removed by hydrodewaxing, distilling the light fractions should not hinder hydrodewaxing, and after hydrodewaxing, they are separated by distillation using a precision distillation apparatus. It is efficient and preferable that the fraction having a boiling point of 371 ° C. or higher and lower than 491 ° C. is 70% by mass or higher by gas chromatography distillation. This hydrodewaxing is performed by contacting the zeolite catalyst with a hydrogen partial pressure of 3 to 15 MPa in the presence of hydrogen at a temperature of 320 to 430 ° C. and an LHSV (liquid space velocity) of 0.2 to 4 h ^−1. The pour point in the lubricating base oil should be −10 ° C. or lower.

  A lubricating base oil having a viscosity index of 120 or more can be obtained by the method as described above, but solvent purification or hydrorefining can be further performed as desired.

  Synthetic oils include α-olefin oligomers, diesters synthesized from dibasic acids such as adipic acid and monohydric alcohols, polyhydric alcohols such as neopentyl glycol, trimethylolpropane, pentaerythritol, and monobasic acids. Polyol esters synthesized from the above, and mixtures thereof.

Furthermore, a mixed oil combining an appropriate mineral oil and a synthetic oil can also be used as the base oil of the engine oil.
Even if it is a mineral oil, a synthetic oil or a mixed oil thereof, when used in the fuel-saving engine oil composition of the present invention, the kinematic viscosity at 100 ° C. is 4.5 mm ² / s or less and the viscosity index is 120 or more. Is preferred.

The fuel-saving engine oil composition of the present invention contains 0.02% by mass or more of an organomolybdenum compound as the amount of molybdenum (Mo) based on the total amount of the engine oil composition. If it is less than 0.02% by mass, sufficient fuel saving cannot be obtained. This organic molybdenum compound is preferably contained in an amount of 0.03 to 0.20% by mass as the amount of molybdenum (Mo).
Specific examples of the organic molybdenum compound include molybdenum dithiocarbamate (MoDTC), molybdenum dithiophosphate (MoDTP), and Mo amine complex. Of these, MoDTC is most preferred, and MoDTP is less preferred because phosphorus poisons the exhaust gas purification three-way catalyst.
In the present invention, as MoDTC, those represented by the following general formula (1) can be preferably used.

In the formula, R _{1 to} R ₄ represent a linear and / or branched alkyl group and / or alkenyl group having 4 to 18 carbon atoms, X represents an oxygen atom or a sulfur atom, and the oxygen atom and sulfur The ratio with the atoms is 1/3 to 3/1. R _{1 to} R ₄ are preferably alkyl groups, particularly preferably branched alkyl groups having 8 to 14 carbon atoms, and specific examples include a butyl group, a 2-ethylhexyl group, an isotridecyl group, and a stearyl group. It is done. Four R < ₁ > -R < ₄ > which exists in 1 molecule may be the same, and may differ. Also, two or more kinds of MoDTCs having different R _{1 to} R ₄ can be mixed and used.
As the benzotriazole and benzotriazole derivative, it is preferable to use a compound represented by the following general formula (2) or (3).

In the above formulas (2) and (3), R ₅ and R ₇ represent a hydrogen atom or a methyl group, and R ₆ and R ₈ contain a hydrogen atom, a hydroxyl group, or a nitrogen atom and / or an oxygen atom. Represents a group having 0 to 20 carbon atoms. From the viewpoint of improving the wear resistance of copper, a benzotriazole derivative is preferable, and R ₆ and R ₈ are preferably a group having 10 to 20 carbon atoms containing a nitrogen atom. Specific examples of the compound include 1H-benzotriazole, 2H-benzotriazole, 1-hydroxybenzotriazole, and 2-hydroxybenzotriazole. These benzotriazoles and benzotriazole derivatives may be used singly or in combination of two or more, and the total amount thereof is 0.03% by mass or more based on the engine oil composition. . If it is less than 0.03 mass%, copper corrosion cannot be sufficiently suppressed. If the amount is too large, not only an effect commensurate with the amount added will be obtained, but also sludge formation may occur in some cases, so it is preferable to contain 5.0% by mass or less.
As the diphenylcarbodiimide and bis (alkylated phenyl) carbodiimide compound, it is preferable to use a compound represented by the following general formula (4).

In said formula (4), R < ₉ > is a C1-C18 alkyl group, n is an integer of 0-5 and shows the number of substituted alkyl groups. Specific examples of bis (alkylphenyl) carbodiimide include ditolylcarbodiimide, bis (isopropylphenyl) carbodiimide, bis (diisopropylphenyl) carbodiimide, bis (triisopropylphenyl) carbodiimide, bis (butylphenyl) carbodiimide, bis (dibutyl) Phenyl) carbodiimide, bis (nonylphenyl) carbodiimide, and the like. These carbodiimide compounds may be used individually by 1 type, and may be used in combination of 2 or more types, and as these total amounts, 0.1 mass% or more is contained on the basis of an engine oil composition. If the amount is too large, not only an effect commensurate with the amount added will be obtained, but also sludge formation may occur in some cases, so it is preferable to contain 5.0% by mass or less.

  The fuel-saving engine oil composition of the present invention can be blended with various additives other than those described above in order to ensure a good balance of performance as a lubricating oil. In particular, in order to ensure excellent cleanliness, sludge dispersibility, and antiwear performance, it is preferable to contain a metallic detergent, an ashless dispersant, and an antiwear agent.

As the metal detergent, it is preferable to use at least one alkaline earth metal detergent selected from alkaline earth metal sulfonate, alkaline earth metal phenate and alkaline earth metal salicylate.
The alkaline earth metal sulfonate is an alkaline earth metal salt of an alkyl aromatic sulfonic acid having a molecular weight of 300 to 1,500, particularly preferably 400 to 700, particularly a magnesium salt and / or a calcium salt, and a calcium salt is preferably used. It is done.

Alkaline earth metal phenates include alkylphenols having a linear or branched alkyl group having 4 to 30 carbon atoms, preferably 6 to 18 carbon atoms, alkylphenol sulfides, alkaline earth metal salts of Mannich reactants of alkylphenols, especially magnesium salts And / or calcium salts are preferably used.
Alkaline earth metal salicylates are preferably alkaline earth metal salts of alkylsalicylic acid having 1 to 30 carbon atoms, preferably 6 to 18 linear or branched alkyl groups, particularly preferably magnesium salts and / or calcium salts. Is preferably used.
The content of the metal detergent is arbitrary, but is 0.05 to 0.22% by mass of metal, preferably 0.1 to 0.2% by weight based on the total weight of the fuel-saving engine oil composition. % Content is desirable.

  Examples of the ashless dispersant include alkenyl succinimides, alkyl succinimides and derivatives thereof derived from polyolefins. Typical succinimides are polyalkylene polyamines containing succinic anhydride substituted with high molecular weight alkenyl or alkyl groups and an average of 4 to 10, more preferably 5 to 7 nitrogen atoms per molecule. It can obtain by reaction with. In particular, a polybutenyl succinimide having a polyisobutene having a number average molecular weight of 700 to 5000, particularly a polyisobutene having a number average molecular weight of 900 to 3000 is more preferable as a high molecular weight alkenyl group or alkyl group.

This polybutenyl succinimide is obtained from polybutene obtained by polymerizing a high-purity isobutene or a mixture of 1-butene and isobutene with a boron fluoride catalyst or an aluminum chloride catalyst, and has a vinylidene structure at the polybutene end. In general, 5 to 100 mol% is contained. The polyalkylene polyamine chain preferably contains 2 to 5, particularly 3 to 4 nitrogen atoms from the viewpoint of obtaining an excellent sludge inhibiting effect.
In addition, as derivatives of polybutenyl succinimide, boron compounds such as boric acid and oxygen-containing organic compounds such as alcohols, aldehydes, ketones, alkylphenols, cyclic carbonates, and organic acids are added to the polybutenyl succinimides. It can be used as a so-called modified succinimide in which a part or all of the remaining amino group and / or imino group is neutralized or amidated by acting. In particular, a boron-containing alkenyl (or alkyl) succinimide obtained by a reaction with a boron compound such as boric acid is excellent in terms of thermal and oxidation stability.
The content of the ashless dispersant is arbitrary, but it is preferably 0.5 to 15% by mass based on the total weight of the fuel-saving engine oil composition.

The fuel-saving engine oil composition of the present invention contains zinc dithiophosphate (ZnDTP) as an antiwear agent in an amount of 0.01 to 0.10 mass% as phosphorus (P) based on the total weight of the engine oil composition. It is preferable that 0.05 to 0.08 is more preferable. When the phosphorus metal element weight contained in ZnDTP with respect to the total weight of the engine oil is less than 0.01% by mass, sufficient anti-wear performance cannot be obtained. The effect of poison is increased.
As ZnDTP, a linear or branched alkyl group having 1 to 24 carbon atoms, a linear or branched alkenyl group having 3 to 24 carbon atoms, or a linear or branched alkylcycloalkyl group And a compound having an aryl group having 6 to 18 carbon atoms or a linear or branched alkylaryl group is preferable. The alkyl group or alkenyl group may be any of primary, secondary, and tertiary.

  Specific examples of zinc dithiophosphate include zinc dipropyldithiophosphate, zinc dibutyldithiophosphate, zinc dipentyldithiophosphate, zinc dihexyldithiophosphate, zinc diisopentyldithiophosphate, zinc diethylhexyldithiophosphate, zinc dioctyldithiophosphate, dinonyl Zinc dithiophosphate, zinc didecyl dithiophosphate, zinc didodecyl dithiophosphate, zinc dipropylphenyl dithiophosphate, zinc dipentylphenyl dithiophosphate, zinc dipropylmethylphenyl dithiophosphate, zinc dinonylphenyl dithiophosphate, zinc didodecylphenyl dithiophosphate And zinc didodecylphenyldithiophosphate.

  If desired, additives such as ashless antioxidants, viscosity index improvers, pour point depressants, metal deactivators, rust inhibitors and antifoaming agents are added to the engine oil of the present invention. be able to.

Next, the present invention will be described specifically by way of examples.
As the base oil, a mineral oil-based base oil (kinematic viscosity: 17.7 mm ² / s (40 ° C.)) obtained by hydrodewaxing a product oil obtained by hydrocracking heavy oil, and 4. 1 mm ² / s (100 ° C.), viscosity index 134) was used.

In the above base oil, MoDTC, benzotriazole derivative (BTA), diphenylcarbodiimide (DPCI), viscosity index improver (VI) and other additives described below are blended in the proportions shown in Table 1 as additives. Engine oils 1 to 3 and Comparative Examples 1 to 5 were prepared. The other additive is an additive mixture consisting of zinc alkyldithiophosphate (ZnDTP), Ca sulfonate, alkenyl succinimide, pour point depressant and antifoaming agent, and is common to all examples and comparative examples. Added in the same amount. The viscosity index improver was added so that the kinematic viscosity at 100 ° C. of the composition was 9.3 to 9.5 mm ² / s (corresponding to 30 in the SAE engine oil viscosity classification) for all of the examples and comparative examples.

MoDTC is a compound represented by the general formula (1), in which R _{1 to} R ₄ are a mixture of 2-ethylhexyl group and isotridecyl group, and the ratio of oxygen atom to sulfur atom is 1/1. The addition amount is the amount as Mo. As the benzotriazole derivative, N, N-bis [(2-ethylhexyl) aminomethyl] -1H-benzotriazole (manufactured by Ciba Specialty, Irgamet 39) was used. A polymethacrylate type was used as a viscosity index improver.

Each of the engine oils of the Examples and Comparative Examples in Table 1 was subjected to a corrosion oxidation stability test, and the analyzed oil was subjected to elemental analysis by ICP. The corrosion oxidation stability test was conducted according to JIS K2503, but the test conditions were changed to 135 ° C. and the test piece was changed to copper (Cu), lead (Pb), and tin (Sn).
In addition, the fuel efficiency of the engine oil under test was evaluated by SRV friction test (test conditions: load 400N, amplitude 1.5mm, vibration frequency 50Hz, temperature 100 ° C). It was.
These results are shown in Table 2.

As shown in Table 2, it can be seen that the engine oil compositions of Examples 1 to 3 exhibit good fuel economy and have less elution of Cu, Pb, and Sn in the corrosion oxidation stability test. Therefore, it exhibits high fuel economy while being excellent in corrosion wear prevention.
On the other hand, in Comparative Example 1 in which MoDTC is not used, the elution of Cu and Pb in the corrosion oxidation stability test is small, but the fuel economy is inferior. In Comparative Example 2 in which MoDTC was blended, although excellent in fuel economy, significant corrosion of Cu occurred in the corrosion oxidation stability test. In Comparative Examples 3 and 4 using a benzotriazole derivative together with MoDTC, if the amount of the benzotriazole derivative is small, the elution of Cu is large, or if the amount of the benzotriazole derivative is large, the elution of Pb is large and the fuel consumption is excellent. It is inferior in corrosion and oxidation stability. It can be seen that even in Comparative Example 5 in which diphenylcarbodiimide was used together with MoDTC, the dissolution of Cu was large and the corrosion oxidation stability was poor.

  The present invention is excellent in corrosion, wear prevention performance, and fuel efficiency, and can be used as an engine oil for internal combustion engines such as gasoline engines, diesel engines, and gas engines.

Claims (3)

  Mineral oil-based and / or synthetic oil-based lubricating base oils with an organomolybdenum compound in an amount of molybdenum (Mo) of 0.02% by mass or more, benzotriazole or a benzotriazole derivative of 0.03% by mass, diphenylcarbodiimide or bis A fuel-saving engine oil composition containing 0.1% by mass or more of an (alkylated phenyl) carbodiimide compound   The fuel-saving engine oil composition according to claim 1, wherein the organic molybdenum compound is molybdenum dithiocarbamate (MoDTC). The fuel-saving engine oil composition according to claim 1 or 2, wherein the lubricating base oil has a kinematic viscosity at 100 ° C of 4.5 mm ² / s or less.