JPH0148319B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a lubricating oil for internal combustion engines that is effective in reducing fuel consumption of diesel automobiles. While petroleum resources are limited and crude oil is becoming heavier, demand for fuels for internal combustion engines, such as gasoline and diesel oil, is on the rise. Therefore, research to reduce the fuel consumption of automobiles from the current level is an extremely important proposition in modern times. One way to meet this demand is to make the viscosity of automobile crankcase oil lower than before or to add new additives called friction modifiers to crankcase oil. It is widely known that there is Conventional friction modifiers include molybdenum disulfide,
Colloidal dispersions such as graphite, sulfurized esters, organic molybdenum compounds, amines, amides,
It has been reported that oil-soluble compounds such as amine salts and phosphates are effective. However, all past data is for gasoline engines, and there is no discussion as to whether it is also valid for diesel engines. In diesel engines, unlike gasoline engines, a large amount of soot generated due to incomplete combustion of light oil mixes into the crankcase oil. Since this soot has surface activity, it is expected to adsorb polar additives in oil, and since it is fine particles, it is expected to have the effect of scraping away the film formed on the friction surface.
Therefore, under such severe conditions, the mode of action as a friction modifier is significantly different from that in a gasoline engine. According to experiments conducted by the present inventors, conventional oil-soluble compounds such as sulfurized esters, organic molybdenum compounds, amines, amides, amine salts, and phosphates have little effect on reducing fuel consumption in diesel engines. Further, conventionally known colloidal dispersions such as molybdenum disulfide and graphite did not exhibit sufficient effects. As described above, conventional friction modifiers have not been sufficiently effective in reducing the fuel consumption of diesel engines. On the other hand, it has already been stated that alkali metal borate hydrates are effective as extreme pressure agents (EP) and antiwear agents (ASLE Preprint No. 76−
AM-1D-2 (1976) and No.77-AM-4D-1
(1977)). However, it is not known that alkali metal borate hydrate itself has a friction-reducing effect, that is, is effective as a friction modifier, and that this can reduce engine fuel consumption. Therefore, the present inventors focused on this alkali metal borate, and as a result of conducting various studies on its effects, it was found that a diesel engine oil composition containing an alkali metal borate hydrate is a diesel engine oil that does not contain a friction modifier. Furthermore, it was confirmed that the oil composition exhibits a much superior fuel efficiency reduction effect compared to diesel engine oil compositions containing the oil-soluble compound or colloidal dispersion as a friction modifier. On the other hand, it is known that lowering the viscosity of the lubricating oil used as a base material is an effective means of improving fuel efficiency, but simply lowering the viscosity leads to a decrease in lubricity and an increase in oil consumption. Undesirable. Therefore, in order to reduce fuel consumption without causing such drawbacks, esterified products of polyalkyl methacrylate, ethylene-propylene copolymer, styrene-diene hydrogenated copolymer, and styrene-maleic anhydride copolymer are used as lubricating oils. Alternatively, multi-grade diesel engine oil is generally used by adding a viscosity index improver such as an amidide. However, the fuel consumption reduction effect of multigrade diesel engine oils to which only these viscosity index improvers were added was insignificant and was by no means satisfactory. An object of the present invention is to provide a multigrade diesel engine oil composition containing an alkali metal borate hydrate as a friction modifier, which exhibits an extremely excellent fuel efficiency improvement effect in diesel engines. That is, in the present invention, for a large proportion of lubricating oil, () alkali metal borate hydrate 0.1 to 5.0
Weight % and () Esterified product or amide of (a) polyalkyl methacrylate, (b) ethylene-propylene copolymer, (c) styrene-diene hydrogenated copolymer, (d) styrene-maleic anhydride copolymer Provided is a multigrade diesel engine oil composition having an excellent fuel efficiency reduction effect, characterized by containing 0.2 to 20.0% by weight of one or more viscosity index improvers selected from the group consisting of chemical compounds. It is. The diesel engine oil composition according to the present invention comprises:
By adding a viscosity index improver to a lubricating oil to make it multi-grade and adding an alkali metal borate hydrate, fuel efficiency is improved synergistically compared to the case where each of these is used alone. Hereinafter, the multigrade diesel engine oil composition according to the present invention will be explained in more detail. The component () referred to in the present invention is an alkali metal borate hydrate, which includes, for example, the U.S. patent
Compounds synthesized by the methods described in 3929650 and 4089790 can be used. U.S. Pat. No. 3,929,650 discloses a fine particle dispersion of an alkali metal borate obtained by carbonating a neutral alkali metal or alkaline earth metal sulfonate in the presence of an alkali metal hydroxide to obtain an ultrabasic sulfonate, and reacting this with boric acid. (An ashless dispersant such as succinimide is sometimes used in the carbonation reaction.)
On the other hand, in US Pat. No. 4,089,790, an aqueous solution of potassium hydroxide and boric acid is added to an oil solution containing a neutral alkaline earth metal sulfonate and/or a succinimide-based ashless dispersant, and stirred vigorously to form a water-in-oil emulsion. A fine particle dispersion of potassium borate hydrate obtained by dehydrating this to a boron/potassium ratio of 2.5 to 4.5 is described. As the alkali metal borate compound according to the present invention, compounds prepared by any of the above methods can be used, but more preferred compounds include potassium borate or borate using neutral calcium sulfonate as a starting material. Mention may be made of sodium acid dispersions. Further, during the carbonation reaction, it is desirable to coexist an ashless dispersant such as succinimide in the reaction system. The proportion of these alkali metal borate hydrates added to the lubricating oil is 0.1 to 5.0% by weight, preferably 0.3 to 2.0% by weight. On the other hand, the component () in the present invention is selected from esters and amides of polyalkyl methacrylate, ethylene-propyne copolymer, styrene-diene hydrogenated copolymer, and styrene-maleic anhydride copolymer. One or more viscosity index improvers. Polyalkyl methacrylate is methacrylic acid
Molecular weight approximately 10000-2000000 obtained by copolymerizing an ester mixture of _C1 - _C18 alcohols
It is a polymer with In addition, dispersed polyalkyl methacrylates containing 20 mol % or less of polar monomers such as vinyl pyrrolidone and morpholine ethyl methacrylate based on the total polymer can also be used. Ethylene-propylene copolymer is obtained by copolymerizing 40 to 60% by weight of ethylene and 60 to 40% by weight of propylene, and has a molecular weight of approximately
20000-250000 polymer. The styrene-diene hydrogenated copolymer is a polymer having a molecular weight of about 20,000 to 100,000 obtained by random or block copolymerization of 30 to 75% diene such as butadiene or isoprene and 70 to 25% styrene, followed by hydrogenation. Esterified products and amidated products of styrene-maleic anhydride copolymers are polymers obtained by copolymerizing styrene and maleic anhydride, and then reacting alcohol and amine to esterify and amidate the copolymer. The proportion of the viscosity index improver added to the lubricating oil is 0.2 to 20.0% by weight, and any amount necessary to prepare the desired multigrade oil can be selected within this range. prepared using these viscosity index improvers,
Examples of multi-grade diesel engine oils that are effective in reducing fuel consumption include 5W-20 and 5W-
30, 7.5W-30, 10W-30, 10W-40, 15W-40,
Examples include 20W−40, but generally
10W-30 and 15W-40 are preferred. As the lubricating oil in the present invention, mineral oil-based or synthetic-based lubricating oils having a viscosity of 2.0 to 40 cst at 100°C can be used alone or in combination. Examples of mineral oil-based lubricants include petroleum-based SAE 10.
base oil (100℃ clay 4.5cst) and SAE20 base oil (100
℃ viscosity 7.5cst). On the other hand, synthetic lubricants include α-olefin oligomers such as 1-decene, polybutene,
Examples include diester, polyol ester, alkylbenzene, and dialkylbenzene, and more specific examples include 1-decene trimer, dodec-2-acid ester, pentaerythritol ester, and trimethylolpropane ester. The diesel engine oil composition according to the present invention contains the above-mentioned two types of additives as essential components, but various other additives can be added as necessary. Metal-based detergents such as zinc dialkyl and diaryldithiophosphates, sulfonates, phenates, phosphonates, salicylates;
Ashless dispersants such as polybutenyl succinimide, Mannitz reaction products of alkylphenols and polyamines, polybutenyl phosphonates, polybutenyl succinic esters, antioxidants, rust inhibitors, oiliness agents, de-foaming agents, etc. are also added. can do. EXAMPLES The effects of the composition according to the present invention will be explained in detail using Examples below, but the scope of the present invention is not limited by these Examples. [Examples 1 to 6, Comparative Examples 1 to 9] Table 1 (Examples 1 to 6) shows composition examples of the present invention.
Comparative examples are shown in Table 2 (Comparative Examples 1 to 9) to show that these compositions are excellent. The fuel-efficient lubricating oil composition for diesel internal combustion engines according to the present invention was evaluated using a sub-vortex engine with a displacement of 2.2, which is one of Japan's representative diesel engines, and using commercially available JIS No. 2 light oil as fuel. (boiling point range 179-360°C, cetane number 60). The test method consisted of 5 steps of constant speed conditions as listed in Table 1, which were independently set by the inventors in accordance with the operating conditions in diesel 6 mode for measuring the concentration of automobile exhaust gas. It is something. This is because there is no official test method for displaying the fuel consumption of diesel engines, but the fuel consumption characteristics of lubricating oil compositions can be relatively easily determined by the test method shown in Table 1. The fuel economy improvement rate is shown in Table 1.
CC class SAE30 diesel engine oil was selected as the reference oil and calculated using the following formula. Fuel economy improvement rate (%) of each test oil = Fuel consumption rate of each test oil (Gr/PS・HR) − Fuel consumption rate of reference oil (Gr/PS・HR) / Fuel consumption rate of reference oil (Gr /PS
・HR)×100

【table】

[Table] ** Percentage of rotational speed at maximum output

【table】

[Table] For example, the lubricating oil composition of Example 2 is made by adding ethylene-propylene copolymer as a viscosity index improver to the lubricating oil to make it multigrade, and adding potassium borate hydrate, but the viscosity It goes without saying that the results of Comparative Examples 2 and 3 are not the same when multigrading is performed by simply adding an index improver (Comparative Example 2) and when only potassium borate hydrate is added (Comparative Example 3). This represents a greater percentage fuel economy improvement than the sum of its parts. This suggests that multi-grading the lubricating oil by adding a viscosity index improver and adding potassium borate hydrate had a synergistic effect on reducing fuel consumption. Further, in the lubricating oil compositions of Examples 1 to 6, friction modifiers such as amines, esters, sulfurized oils, organic molybdenum compounds, molybdenum disulfide, and graphite were added instead of the potassium borate hydrate according to the present invention. Lubricating oil composition (Comparative Examples 4 to 9)
It has a much better fuel economy improvement rate. From the above results, it is clear that the present invention makes it possible to obtain a multigrade diesel engine oil composition that is much more effective in reducing fuel consumption than conventional compositions.

Claims (1)

[Scope of Claims] 1. Based on a large amount of lubricating oil, () 0.1 to 5.0% by weight of alkali metal borate hydrate and () one member selected from the group consisting of (a) to (d) below or Two or more types of viscosity index improvers 0.2 to 20.0
Contains esterified or amidated products of (a) polyalkyl methacrylate (b) ethylene-propylene copolymer (c) styrene-diene hydrogenated copolymer and (d) styrene-maleic anhydride copolymer (wt%) A multi-grade diesel engine oil composition with excellent fuel efficiency reduction effects.