JPH06184578A - Engine oil composition - Google Patents

Abstract

PURPOSE:To obtain an automotive engine oil (lubricating oil compsn. for automobiles) low in phosphorus concn but capable of exhibiting an excellent abrasion resistance as compared with an engine oil wherein use is made of a conventional level of a zinc dialkyldithiophosphate. CONSTITUTION:In an engine oil compsn. comprising a metal cleaner, a zinc dialkyldithiophosphate and an ash-free boron-contg. dispersant dissolved or dispersed in a base oil, at least one additive selected from among aliph. amide compds. and dithiocarbamate compds. is further dissolved or dispersed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine oil (lubricating oil for internal combustion engine) exhibiting excellent performance in wear resistance, particularly in reducing wear that tends to occur in a valve train.

[0002]

2. Description of the Related Art In ordinary automobile gasoline engines and diesel engines, bearings, piston ring parts, and valve trains such as cams and tappets, cams and rocker arms are parts with severe lubrication conditions,
The ability to prevent wear in this area is extremely important for engine oil.

The engine oil is a mineral oil or a synthetic oil as a base oil, and the base oil alone can satisfy various performances required for the engine oil (wear resistance, detergency, antioxidation, etc.). Since it does not become an engine oil (lubricating oil for internal combustion engine), it is generally used as an additive in order to impart various properties thereof, such as an ashless dispersant, a metal-based detergent, an antiwear agent, and an antioxidant. The agent, the viscosity index improver, and various other auxiliary functional additives are combined and used in the form of a compounded composition.

Various types of the above-mentioned additives are known and used, and as the wear resistance improver, zinc dialkyldithiophosphate which also functions as an antioxidant at the same time is used. Is common. That is, since this zinc dialkyldithiophosphate has very excellent properties as an antiwear agent and at the same time exhibits high performance as an antioxidant, it is used in almost all of the various engine oils in practical use. Has been.

However, in recent years, HC, CO, and NO contained in exhaust gas generated by combustion in the engine
Toxic substances such as _X came to be regulated, and in order to remove those toxic substances in the exhaust gas, a catalyst device combining metals such as platinum and rhodium was attached to the exhaust gas outlet of the automobile, It is common to convert those toxic substances into non-toxic substances (purification). However, the phosphorus component contained in the zinc dialkyldithiophosphate is a component that poisons the above catalyst component, and there is a problem in that the activity of the catalyst device is lowered by using the engine oil containing the phosphorus component. Therefore, in order to maintain the activity and durability of the exhaust gas purifying catalyst device at a high level, there is a strong trend that the phosphorus content in engine oil should be reduced, and the amount of zinc dialkyldithiophosphate used should be reduced. It tends to decrease.

Further, recently, there is a tendency to drive an automobile engine under more severe conditions (high speed, high output), and from the viewpoint of fuel efficiency, the viscosity resistance of engine oil is lowered to reduce the viscous resistance. There is. Due to these factors, the lubrication conditions become severe, and the wear resistance required for engine oil is becoming more important. Therefore, the conventional engine oil containing the detergent-dispersant and zinc dialkyldithiophosphate as the main additive component is likely to cause abrasion troubles, and countermeasures against such troubles are required.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the amount of phosphorus used and to exhibit an abrasion resistance equivalent to or superior to that of an engine oil using a conventional level of zinc dialkyldithiophosphate. To provide an engine oil for automobiles (lubricating oil composition for automobiles).

Another object of the present invention is to provide an engine oil for automobiles which exhibits high wear resistance even if it has a low viscosity.

[0009]

The present invention provides a base oil containing a metal-based detergent, a zinc dialkyldithiophosphate, a boron-containing ashless dispersant, and one of the following compounds (1) or (2). Alternatively, it is an engine oil composition in which both are dissolved or dispersed. (1) Aliphatic amide compound (2) Dithiocarbamate compound

The engine oil composition of the present invention is obtained by dissolving or dispersing a metallic detergent, a zinc dialkyldithiophosphate, and a boron-containing ashless dispersant in a base oil, which is further aliphatic. It is characterized in that at least one additive component selected from the amide compound and the dithiocarbamate compound is dissolved or dispersed. These additive components are contained in the engine oil composition in an amount of 0.01 to 3% by weight.
(Particularly, 0.1 to 2% by weight) is preferably added.

Various kinds of metal-based detergents, zinc dialkyldithiophosphates, boric acid-containing ashless dispersants, and base oils are known. In the preparation of the engine oil of the present invention, those known materials are also known. Alternatively, the similar compound can be used. Also, a normal engine oil composition,
A viscosity index improver is added to adjust the viscosity. Next, typical examples of these various materials will be described.

As the metallic detergent, a metal phenate or sulfonate is generally used. The metal phenate is an alkaline earth metal salt of an alkylphenol sulfide to which an alkyl group having about 8 to 30 carbon atoms is added. In this case, the alkaline earth metal generally used includes calcium, magnesium or barium. Sulfonate has a molecular weight of about 400-60
It is an alkaline earth metal salt of a sulfonate of a mineral oil of 0 or an alkyl-substituted aromatic compound. Examples of the alkaline earth metal generally used in this case include calcium, magnesium and barium. These phenates or sulfonates can be used alone or in various combinations. Also, alkaline earth metal salicylates, phosphonates,
Metallic detergents such as naphthenates can be used alone or in combination with the phenates or sulfonates described above. In addition, these metallic detergents may be of a neutral type or of an overbased type having a base number of 150 to 300 or more. Metal-based detergents are usually
It is blended so that the concentration in engine oil is 0.5 to 20% by weight.

Zinc dialkyldithiophosphate (or simply "zinc dithiophosphate") generally contains an alkyl group having 3 to 18 carbon atoms or an alkyl group having 3 to 18 carbon atoms as an antioxidant or an antiwear agent. Preference is given to using zinc dihydrocarbyl dithiophosphates having alkylaryl groups. This is usually blended so that the concentration in the engine oil will be 0.1 to 3% by weight.

As a typical example of the ashless dispersant containing boron, succinimide, succinic acid ester, benzylamine or a derivative of these compounds to which an alkyl group or an alkenyl group having a molecular weight of about 700 to 3000 is added is borated. What was processed and introduced the boron in the molecular structure is used. These boron-containing ashless dispersants preferably contain 0.1 to 5% by weight (particularly 0.2 to 2% by weight) of boron, and particularly 0.1 to 5% of boron. It is preferably a succinimide derivative containing wt%. The boron-containing ashless dispersant is usually blended so that the concentration in the engine oil is 0.5 to 15% by weight. It should be noted that the ashless dispersant containing boron may be used in combination with the ashless dispersant containing no boron.

Viscosity index improvers are generally polyalkylmethacrylates, ethylene-propylene copolymers,
Styrene-butadiene copolymer, polyisoprene and the like are used. Alternatively, a dispersion-type or multifunctional viscosity index improver imparting dispersion performance may be used. These viscosity index improvers can be used alone or in various combinations. The viscosity index improver is usually blended so that the concentration of the viscosity index improver in the engine oil is 0.5 to 20% by weight, although it depends on the desired viscosity of the target engine oil.

As the base oil which occupies most of the composition of the engine oil, mineral oil or synthetic oil can be used alone or in combination.

Next, the aliphatic amide compound and dithiocarbamate compound added to the engine oil of the present invention will be described in detail.

(1) Aliphatic amide compound The aliphatic amide compound added to the engine oil composition of the present invention is preferably an amide of a fatty acid having 8 to 24 (particularly 12 to 20) carbon atoms or its derivative. The fatty acid component may be saturated or unsaturated, but unsaturated is preferred. In addition, other functional groups may be included.
Especially preferred are oleic acid amide and sulfurized oleic acid amide.

(2) Dithiocarbamate Compound Examples of the dithiocarbamate compound added to the engine oil composition of the present invention include alkylthiocarbamoyl compounds represented by the following general formula.

[0020]

[Chemical 1]

(However, R ¹ , R ² , R ³ and R ⁴ are
C1 to C1 which may be the same or different from each other
18 represents an alkyl group, and (X) represents S, S-
_{S, S-CH 2 -S,} S-CH 2 CH 2 -S, S-CH
₂ CH ₂ CH ₂ -S or S-CH ₂ CH (CH,
₃ ) represents -S. ).

The above-mentioned alkylthiocarbamoyl compounds have been conventionally used as additives for rubber vulcanization accelerators, gear oils, turbine oils, etc., and are known compounds. The alkyl group of the above general formula may be either a straight chain type or a branched chain type, and examples thereof include
Methyl, ethyl, propyl, n-butyl, isobutyl,
Mention may be made of alkyl groups such as pentyl, isopentyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl and dodecyl. 1 carbon is preferred
10 to 10 alkyl groups. Further, specific examples of the alkylthiocarbamoyl compound of the above general formula include methylenebis (dibutyldithiocarbamate), bis (dimethylthiocarbamoyl) monosulfide, bis (dimethylthiocarbamoyl) disulfide, bis (dibutylthiocarbamoyl) disulfide, bis (dia Examples thereof include milthiocarbamoyl) disulfide and bis (dioctylthiocarbamoyl) disulfide. Further, metal dithiocarbamates such as zinc dithiocarbamate, copper dithiocarbamate and molybdenum dithiocarbamate can also be used, and the use of these metal dithiocarbamates is particularly advantageous. Each of these compounds may be used alone or in combination of two or more.

It is preferable that a fatty acid / borate ester is further added to the engine oil composition of the present invention.
The fatty acid / borate ester is an ester composed of glycerin, a fatty acid having 8 to 24 carbon atoms and boric acid, and has any of the following general formulas (I), (II) and (III). Preferably there is.

[0024]

[Chemical 2]

[0025]

[Chemical 3]

[0026]

[Chemical 4]

In the above general formulas (I), (II) and (III), X, Y and Z may be the same or different, and a hydroxyl group (-OH) or an alkylcarboxyl group (-OCOR: R). Represents a straight-chain or branched-chain, saturated or unsaturated alkyl group having 7 to 23 carbon atoms.

The engine oil of the present invention may contain various auxiliary functional additives in addition to the above components, if desired. Examples of auxiliary function additives include known antioxidants, extreme pressure additives, corrosion inhibitors, rust inhibitors, friction modifiers, defoamers, pour point depressants and the like. Also,
A wear resistance improver, a multifunctional additive (organic molybdenum compound such as molybdenum dithiophosphate) may be combined.

In preparing the engine oil of the present invention, each additive component may be added to the base oil separately,
Generally, a metal-based detergent, a ashless dispersant containing boron, zinc dithiophosphate, and (1) an aliphatic amide compound and / or (2) a dithiocarbamate compound are combined as an essential component, and other optional additions are made. Prepare a compounding agent prepared by adding the agent components (generally dissolved and dispersed in a base oil at a high concentration) in advance, and a viscosity index improver,
Then, if desired, it is desirable in terms of compounding technology to add another optional component to the base oil to prepare an engine oil. In such cases, the ashless dispersant is 10 to 700 parts by weight, and the aliphatic amide compound and / or dithiocarbamate compound is 2 to 100 parts by weight of the metal-based detergent.
It is preferable to add 200 parts by weight.

[0030]

EXAMPLES As shown in Table 1, the same paraffinic mineral oil (viscosity index 100), viscosity index improver, pour point depressant, metallic detergent, zinc dithiophosphate, and antioxidant were used. Various ashless dispersants and other additive components were added thereto to produce various engine oils (prototype engine oils Nos. 1 to 4 according to the present invention and comparative trial engine oil Nos.
5-8, the viscosity grade was SAE5W30, the phosphorus content level in the engine oil was 0.08% by weight), and the performance of the prototype engine oils regarding valve wear was evaluated by the following method. .

A piston motor and a connecting rod portion were removed from a gasoline engine (Toyota 3A type) of in-line 4-cylinder, displacement 1.5L, OHC type, and a bench motoring test in which an electric motor was driven was performed (JASO M328-9).
1). The motoring test conditions are oil temperature 60-65.
Operating at 200 ° C for 200 hours at 1000 ± 50rpm, the degree of scuffing wear of rocker arm pad (cam contact surface of rocker follower) after completion of operation (evaluated by the area of worn part) is a demerit score from 0 to 100.
(0 is the best and 100 is the worst).

Table 1 ──────────────────────────────────── Prototype engine oil prototype Jin oil No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8 −−−−−− Inventive product −−−−−−−−−−− Comparative product −−−−−− ─────────────── Ashless dispersant I ----------------- 5.0 5.0 5.0 5.0 ---- Boron-containing ashless Dispersant II 5.0 5.0 5.0 5.0 5.0 --- --- --- 5.0 Metallic detergent 2.7 2.7 2.7 2.7 2.7 2.7 2 .7 2.7 Zinc dithiophosphate 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 Antioxidant 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Aliphatic amide compound 0.5 --- 0.2 0.2 --- 0.5 --- --- Dithiocarbamate --- 0.5 --- 0. 3 −−−−−− 0.5 −−− Borate ester −−−−−− 0.3 −−− −−−−−−−−−−−− Viscosity index improver 7.7 7.7 7.7 7.7 7.7 7.7 7.7 7.7 Pour point depressant 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Paraffinic mineral oil 81.5 81.5 81.5 81.5 82.0 81.5 81.5 82.0 ────────────────────── ─────────────── Valve system motoring test (demerit score) 1.4 2.8 0 0 73 26 31 31 11 ───────────── ───────────────────────

Details of the additives shown in Table 1 above are as follows. If necessary, additional additives such as defoaming agent were added.

Ashless Dispersant I: Succinimide Boron-containing Ashless Dispersant II: Boric Acid Modified Succinimide (Boron Content: 0.4% by Weight) Metallic Detergent: Calcium Sulfonate and Calcium Phenate A mixture of zinc dithiophosphate: zinc dihydrocarbyl dithiophosphate (secondary alkyl type having 4 to 6 carbon atoms, phosphorus content:
(7.2 wt%) Antioxidant: Mixture of dialkyldiphenylamine and hindered phenol Aliphatic amide compound: Oleic acid amide Dithiocarbamate: Molybdenum dithiocarbamate Boric acid ester: Oleic acid residue per mol of boric acid residue A group of about 1 mol and a glycerin residue of about 2 mol, wherein the compound of the general formula (I) and the compound of the general formula (II) (wherein one of X, Y and Z is an oleic acid residue, The balance is a mixture of hydroxyl groups) Viscosity index improver: Ethylene / propylene copolymer derivative (dispersion type) Pour point depressant: Polyalkylmethacrylate Paraffinic mineral oil: 100 neutral with a viscosity index of 100

As is apparent from the test data shown in Table 1, engine oils prepared by adding the boron-containing ashless dispersant of the present invention in combination with one or both of an aliphatic amide compound and dithiocarbamate. Shows high resistance to valve train wear.

[0036]

Industrial Applicability The lubricating base oil of the present invention contains a metal detergent, zinc dialkyldithiophosphate (zinc dithiophosphate), a ashless dispersant containing boron, and one of an aliphatic amide compound or a dithiocarbamate compound, or Engine oils prepared with both added are highly resistant to valve train wear, even at relatively low phosphorus content levels and at relatively low viscosities.

Front page continuation (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location C10M 135: 30 137: 10 A 9159-4H 135: 10 139: 00) A 9159-4H C10N 10:04 10: 12 30:06 40:25 60:14

Claims (3)

[Claims] 1. An engine obtained by dissolving or dispersing a metallic detergent, a zinc dialkyldithiophosphate, a boron-containing ashless dispersant, and one or both of the following compounds (1) and (2) in a base oil. Oil composition. (1) Aliphatic amide compound (2) Dithiocarbamate compound 2. The engine oil composition according to claim 1, further comprising a fatty acid borate ester of a polyhydric alcohol. 3. The boron-containing ashless dispersant is boron 0.1.
The engine oil composition according to claim 1, which is a succinimide derivative containing 5 to 5% by weight.