JPS6314035B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a lubricating oil composition for internal combustion engines, which contains as an essential component an additive composition in which zinc dialkyldithiophosphate is blended with magnesium sulfonate, calcium phenate, and alkenyl succinimide having a high base number. In general, in internal combustion engines, the valve train system, such as cams, valves, and rocker arms, is the part that is subject to the most severe load conditions, and it is important for lubricating oils for internal combustion engines, that is, engine oils, to have the ability to prevent wear in these parts. This is extremely important. Conventionally, engine oils contain a certain amount of zinc dialkyldithiophosphate, which is an anti-wear agent, e.g.
It has been said that by adding 0.5wt% or more, the problem of valve train wear does not occur at all. However, as load conditions and temperature conditions become more severe in recent engines due to exhaust gas countermeasures, etc., it has become clear that simply increasing the amount of conventional zinc dialkyldithiophosphate does not provide sufficient anti-wear properties. came. The present inventors focused on the fact that zinc dialkyldithiophosphate in such engine oils is the most dominant factor in the wear of valve train systems, and as a result of intensive research into this wear phenomenon, they discovered that a certain additive to zinc dialkyldithiophosphate It has been discovered that by combining these agents, a lubricating oil composition for internal combustion engines having optimal anti-wear properties for valve train systems can be obtained. The lubricating oil composition for internal combustion engines of the present invention contains (a) high base number magnesium sulfonate in a large proportion of the lubricating oil base oil.
0.2-1.5wt% (b) Calcium phenate 0.1-2.0wt% (c) Alkenylsuccinimide or its derivative
It is characterized by adding 1.0 to 10.0 wt% and (d) 0.3 to 2.0 wt% of zinc dialkyldithiophosphate. Among the additives used in the present invention, (a) high base value magnesium sulfonate has a base value of 200 to 400 mgKOH/g and a magnesium content.
It is preferably 5.0 to 12.0%, and may be produced, for example, by carbonating a magnesium salt of petroleum sulfonic acid or synthetic sulfonic acid. (b) Calcium phenate can be produced by a commonly known method, such as by carbonating a calcium salt of an alkyl phenol or a sulfurized alkyl phenol, or by carbonating this calcium salt. 300mg
KOH/g and calcium content of 2.0 to 12.0% are preferably used. (c) Alkenylsuccinimide or its derivatives are obtained by reacting polyolefin with a molecular weight of 300 to 3000 with maleic anhydride and then imidizing it with a polyamine, or by reacting the obtained imide with an aromatic polycarboxylic acid. , those in which the remaining amino groups are partially amidated are used. For example, polybutene having a molecular weight of 900 may be reacted with maleic anhydride and then imidized with tetraethylenepentamine, or polybutene may be reacted with trimellitic acid. (d) Zinc dialkyldithiophosphate has the general formula In the formula, R ₁ , R ₂ , R ₃ and R ₄ are C ₃ to
The _C18 alkyl group or alkaryl group may be the same or different. For example, isopropyl group, sec-butyl group, isobutyl group, n-amyl group, isoamyl group, 4-methylpentyl group,
Examples include 2-ethylhexyl group, isodecyl group, and dodecylphenyl group. Further, the lubricating base oil used in the present invention may have a normal lubricating oil viscosity and a viscosity index of 85 to 120, and may be a mineral oil type, a synthetic type, or a mixture thereof. In the case of mineral oil-based lubricating oils, it is sufficient to use lubricating oils refined by an appropriate combination of solvent refining, hydrorefining, etc., and in the case of synthetic lubricating oils, _C2
~ α-olefin oligomers which are polymers of C ₁₂ α-olefins, various C ₄ to _{C 12} dialkyl diesters such as sebacate, azelate, and adipate including dioctyl sebacate;
Polyol esters including esters obtained from neopentyl polyols such as trimethylolpropane and pentaerythritol and C ₃ to _{C 12} monobasic acids, and alkylbenzenes having C ₉ to C ₄₀ alkyl groups. Synthetic lubricating oils can be used alone or in combination as the base oil. Furthermore, the blending ratio of additives in the lubricating oil composition of the present invention must be strictly adhered to since it has an extremely sensitive effect on lubricating oil performance. Specifically, (a) high base value magnesium Sulfonate is 0.2
~1.5wt%, preferably 0.5-1.0wt% (b) Calcium phenate 0.1-2.0wt%, preferably 0.1-1.2wt% (c) Alkenylsuccinimide or its derivatives 1.0-10.0wt%, preferably is 3.0-10.0wt% (d) Zinc dialkyldithiophosphate is 0.3-2.0wt%,
It is necessary to blend preferably 0.5 to 1.0 wt%, and if any one component deviates from the above range, the additive effect will be extremely reduced and it will not be possible to exhibit the desired wear resistance. become unable. In the lubricating oil composition of the present invention, the above-mentioned (a)
In addition to the additives listed in ~(d), viscosity index improvers such as polymethacrylate, ethylene propylene copolymer, hydride of styrene-isoprene copolymer, or polyisobutylene, and oxidation inhibitors such as phenol or aromatic amine. Various additives such as antifoaming agents, antifoaming agents such as silicone oil, and polyalkylene glycol ether type rust inhibitors can be blended as appropriate. The composition of the present invention exhibits extremely high antiwear properties even when the amount of zinc dialkyldithiophosphate is kept to a low level, and at the same time, phosphorus, which is considered to be a catalyst poison in catalytic converters used as a measure against recent automobile exhaust gas, is exhibited. This also has the additional effect of being able to provide engine oil that meets the requirements of the times. On the other hand, the high basic value magnesium sulfonate, which is one of the components of the present invention, becomes coarse particles of the magnesium carbonate contained therein under low-temperature operating conditions accompanied by the contamination of a considerable amount of condensed water. It is generally recognized that this causes clogging. However, only by using the additive combination of the present invention can the clogging of the oil filter due to coarsening of magnesium carbonate be prevented without impairing the anti-wear properties of the valve train. The lubricating oil composition of the present invention has excellent anti-wear properties for valve train systems as described above, and at the same time does not cause clogging of oil filters. The contents of the present invention will be explained in detail below using examples. Examples 1 to 4 and Comparative Examples 1 to 9 As Example 1, a lubricating oil composition having the following composition was prepared. Γ SAE30 solvent refined mineral oil 93.3wt% Γ Carbonated Mg sulfonate with base number 400 0.7 〃 Γ Carbonated Ca phenate with base number 140 0.3 〃 Γ Imide of polybutenylsuccinic acid and tetraethylenepentamine 5.0 〃 Γ Zn di(4-methyl Pentyl dithiophosphate 0.7 Γ Silicone oil 0.002 Table 1 shows the compositions of the compositions used in other Examples and Comparative Examples, including the composition of Example 1 above. The performances of the compositions shown in Examples and the compositions of Comparative Examples were compared in the following two tests. A Valve train wear test (motor driven) Engine Domestic company A 1800c.c. OHC type Rotation speed 2000rpm Load None Oil temperature 90℃ Valve spring load 125% of normal Test time 200hr The damage state of the rocker pad after the test was reduced to 0 ~
Expressed with a demerit score of 100 (0 = best,
100 = worst. ) B Oil filter clogging test Engine Domestic B company 1300c.c.OHV type Operating conditions

[Table] Stage ~ is one cycle, and the system is operated for 3 cycles (12 hours) a day and stopped for 12 hours. Repeat this for 36 cycles (12 days). An oil filter is installed during the test, and clogging of the filter is detected by measuring the differential pressure across the oil filter. Differential pressure is 0.5
It is expressed as the number of cycles required to reach Kg/cm ² (under normal conditions, the differential pressure is 0 or about 0.05 Kg/cm ² ).
The evaluation results are also shown in Table 1, and if even one of the four essential components, which are the key points of the present invention, is missing, or if the amount added is outside the range of the present invention, good valve train wear prevention properties will be lost. It is clear that this cannot be obtained. On the other hand, when benzylamine or succinic acid ester is used instead of alkenyl succinimide, or when no ashless dispersant is used at all, oil filters are found to become clogged. It is therefore clear that only those which meet the composition range of the present invention will exhibit exceptional performance in both valve train wear and oil filter clogging.

【table】

[Table] *2 Oligomer of 1-decene *3 2-ethylhexyl sebacate

Claims (1)

[Scope of Claims] 1. (a) High basic value magnesium sulfonate in a large proportion of lubricating base oil
0.2-1.5wt% (b) Calcium phenate 0.1-2.0wt% (c) Alkenylsuccinimide or its derivative
A lubricating oil composition for an internal combustion engine, comprising: 1.0 to 10.0 wt% and (d) 0.3 to 2.0 wt% of zinc dialkyldithiophosphate.