JP3241603B2 - Lubricating oil for diesel engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition of a lubricating oil used in a diesel engine, and more particularly, to a composition of a lubricating oil for a diesel engine (hereinafter, also simply referred to as engine oil) capable of suppressing corrosion and wear caused by sulfuric acid. About.

[0002]

2. Description of the Related Art Light oil and heavy oil used as fuel for diesel engines contain sulfur, and the exhaust gas contains sulfur oxides during combustion. recent years,
For diesel engines for land use such as automobiles, diesel oil with low sulfur content is often used, but at the same time, EGR (Exhaust Gas Recircu
lation, exhaust gas recirculation), the exhaust gas contains a large amount of sulfur oxides.

[0003] Exhaust gas contains water together with sulfur oxides, which react to produce sulfuric acid. A part of the generated sulfuric acid will be contained in the engine oil, and will corrode and wear the engine members. Therefore, conventionally, a relatively large amount of a basic metal-based detergent / dispersant has been added to neutralize the sulfuric acid.

[0004]

However, when a relatively large amount of a metal-based detergent / dispersant is added to engine oil, part of the engine oil is burned in the combustion chamber. It will be contained in gas.
The exhaust gas of a diesel engine is exhausted through a filter that removes exhaust gas catalysts and particulates, and such ash poisons the exhaust gas catalyst and clogs the filter.

An object of the present invention is to provide a diesel engine lubricating oil which can suppress corrosion and abrasion due to sulfuric acid even when a relatively small amount of a metal-based detergent / dispersant is added.

[0006]

Means for Solving the Problems The present inventor has conducted intensive studies in order to achieve the above-mentioned object, and as a result, by combining a specific metal-based detergent and dispersant, a diesel engine for diesel engines having a relatively low ash content has been obtained. The present inventors have found that even a lubricating oil can suppress corrosion and wear caused by sulfuric acid, and have completed the present invention.

That is, the lubricating oil for diesel engines according to the present invention is based on mineral oil and / or synthetic oil,
(A) A highly basic calcium salicylate having a base number of 100 mgKOH / g or more is expressed as calcium in an amount of from 0.04 to
0.2% by weight, (b) 0.01 to 0.1% by weight of a low basic calcium salicylate having a base number of less than 100 mg KOH / g as calcium, and (c) nitrogen amount of polyalkenyl succinimide. Or (a) a base number of 100 mg KOH
/ G or more of a high basic magnesium salicylate as 0.04 to 0.2% by weight as a magnesium amount, and (b) a low basic calcium salicylate having a base number of less than 100 mg KOH / g as a calcium amount of 0.01 to 0.2%. 0.1% by weight,
And (c) a polyalkenyl succinimide containing not less than 0.02% by weight of nitrogen.

[0008]

[Preferred Embodiment]

[Base oil] The base oil used in the present invention is a mineral oil or a synthetic oil of a lubricating oil fraction, and the base oil used as a basic component occupying most of the lubricating oil composition is any lubricating base oil. Can be used. Specifically, as a mineral oil, a fraction obtained by vacuum distillation of a normal distillation residue such as a paraffinic crude oil is subjected to solvent extraction with furfural or the like, hydrorefining, or solvent dewaxing with MEK / toluene or the like. Base oil obtained by treating by the method, lubricating base oil obtained by treating the deasphalted oil obtained by deasphalting the residue of the vacuum distillation by the above-mentioned appropriate treatment method, slack wax A highly refined base oil obtained by dewaxing a suitable fraction of an isomerized oil obtained by hydroisomerization of MEK / toluene with a MEK / toluene solvent, and a mixture thereof can be used.

Examples of the synthetic oil include α-olefin oligomers, diesters synthesized from dibasic acids such as adipic acid and primary alcohols, and polyhydric alcohols such as neopentyl glycol, trimethylolpropane and pentaerythritol. Examples include polyol esters, alkylbenzenes, polyoxyalkylene glycols, and mixtures thereof synthesized from monobasic acids. Furthermore, it goes without saying that a mixed oil obtained by combining an appropriate mineral oil and a synthetic oil can also be used as the base oil of the present invention.

[Overbased calcium salicylate / magnesium salicylate] The overbased calcium salicylate or magnesium salicylate used in the present invention is:
The base number is 100 mgKOH / g or more.
150-350 mgKOH / g is preferred. Usually, the basicity is 1.0 or more, and in particular, 1.5 to 3.
0 is preferred. Here, the basicity is ([total Ca or M
g] / [alkylsalicylic acid equivalent])-1. Specifically, Shell Chemical SAP001, S
AP005, SAP007, OSCA43 manufactured by Oska Chemical
5B, OSCA463, or the like can be used.

The amount of the highly basic salicylate added is 0.04 to 0.2% by weight in terms of the weight of metal (weight of calcium or magnesium), preferably 0.1 to 0.1%, based on the total weight of the lubricating oil. ~ 0.2% by weight. If the addition amount is less than 0.04% by weight, the effect of suppressing corrosion and abrasion by sulfuric acid is not sufficient, and if added in excess of 0.2% by weight, the ash content increases and is not suitable.

[Low-Basic Calcium Salicylate] The low-basic calcium salicylate used in the present invention has a base number of less than 100 mgKOH / g, especially
00 mg KOH / g is preferred. Usually, the basicity is less than 1.0, and particularly preferably 0.3 to 1.0. Here, the basicity is defined as ([equivalent of total Ca] / [equivalent of alkylsalicylic acid derivative])-1. Specifically, SAP002 manufactured by Shell Chemical Co., and O
SCA431B or the like is used.

The amount of the calcium salicylate having a low base number relative to the total weight of the lubricating oil is 0.01 to 0.1% by weight in terms of calcium, and preferably 0.0 to 0.1% by weight.
5 to 0.1% by weight. This added amount is 0.01% by weight
If it is less than 30, the dispersion cleanliness is not sufficient, and even if it exceeds 0.2% by weight, the ash content increases, which is not appropriate.

[Polyalkenyl succinimide] As the polyalkenyl succinimide used in the present invention, a bis-form represented by the following formula 1 is preferably used. The mono-form represented by the following chemical formula 2 is also used.

Embedded image

Embedded image In the formula, R ₁ and R ₃ are olefin oligomer residues having 30 or more carbon atoms, R ₂ is an alkylene group having 2 to 4 carbon atoms, and m is an integer of 1 to 10.

Derivatives such as those obtained by adding boron to the polyalkenyl succinimide represented by Chemical Formulas 1 and 2 can also be used as the polyalkenyl succinimide of the present invention. The polyalkenyl succinimide of the present invention has an average molecular weight of 500 to 10000, particularly 1
000-5000 are preferably used.

The amount of polyalkenyl succinimide added to the total lubricating oil weight is 0.02 in terms of nitrogen weight.
% Or more, preferably 0.03 to 0.12% by weight. If the added amount is less than 0.02% by weight, the effect of suppressing corrosion and wear by sulfuric acid is not sufficient. Even if added in excess of 0.12% by weight, such an inhibitory effect is saturated,
It is not preferable in terms of cost.

[Other Additives] In the diesel engine of the present invention, lubricating oil additives other than those described above are added as necessary to improve the overall performance in order to ensure the performance adapted to the application. Can be done. Such engine oil additives include antiwear agents such as organometallic antiwear agents such as ZnDTP and MoDTC; viscosity index improvers such as olefin copolymers and polymethacrylates; antioxidants; pour point depressants; Agents and defoamers.

[0018]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. As a metal-based detergent and dispersant, one of highly basic salicylates, phenates, and sulfonates,
The test oil No. was obtained by combining one of low basic salicylate, phenate and sulfonate. 1 to 15
Prepared as

Sample oil No. Tables 1 and 2 show the amounts of the metal-based detergent / dispersants Nos. 1 to 15 as metal weight% with respect to the total weight of the engine oil. These test oils contained 4% by weight (0.02% by weight of nitrogen) of polyalkenyl succinimide (bis-form represented by Chemical Formula 1, molecular weight: about 1500),
2% by weight of zinc dithiophosphate, 0.3% by weight of pour point depressant, and 5 ppm of antifoaming agent are commonly added. As the base oil, a mineral oil base oil obtained by subjecting a vacuum distillation fraction of a paraffinic crude oil to solvent extraction with furfural, hydrorefining, and solvent dewaxing with MEK / toluene was used. Kinematic viscosity of this base oil at 40 ° C .:
72.42 mm ² / s, viscosity index: 101.

[0020]

[Table 1]

[0021]

[Table 2]

The prepared test oil No. For 1 to 15,
Corrosion by sulfuric acid, oxidative stability by ISOT test, dispersion cleanliness by panel coker test, and heat resistance by hot tube test were evaluated. The results are shown in Tables 1 and 2.

The acid neutralizing ability was evaluated as the corrosiveness with sulfuric acid. The acid neutralizing ability was determined by adding 1 g of 75% sulfuric acid to 99 g of a test oil at 60 ° C., stirring the mixture using a homomixer, and then adding a 25 × 50 mm JIS steel plate (JIS G3141 SPCC-S
B) was immersed for 72 hours, and iron (F) dissolved in this test oil was
e) was analyzed by ICP. Dissolved iron (Fe)
The results are shown in Tables 1 and 2 in pm units. The larger the amount dissolved, the higher the corrosiveness due to sulfuric acid.

The ISOT test was performed at 165.5 ° C. for 72 hours in accordance with JIS K2514. As the evaluation, the change in viscosity at 40 ° C. before and after the test was defined as a viscosity ratio, the increase in total acid value before and after the test was measured in mg KOH / g, and the total base number remaining was the total base number remaining after the test. Was measured in mg KOH / g and is shown in Tables 1 and 2. The lower the viscosity ratio and the total acid value increase, the higher the stability against oxidation. The higher the total base number residue, the higher the stability to oxidation.

The panel coker test is performed by the Fedral Test Method
In accordance with No. 791B, Method No. 3462, the test was carried out at a temperature of 320 ° C., and the amount of deposited deposit was measured in mg units. The lower the precipitation amount, the higher the clean dispersibility.
The hot tube test was performed at a temperature of 290 ° C. using a hot tube tester manufactured by Komatsu Engineering Co., Ltd.
The scores were measured in units of 0.5, and are shown in Tables 1 and 2. The higher the value, the better the heat resistance.

As can be seen from Tables 1 and 2, the test oil No. obtained by combining a highly basic Ca salicylate and a low basic Ca salicylate was used. Test oil No. 1 and a combination of a highly basic Mg salicylate and a low basic Ca salicylate. 10 shows that sulfuric acid corrosion is small, oxidative stability is high, and clean dispersibility is excellent.

Further, the acid neutralizing ability of the test oil in which the addition amount of the polyalkenyl succinimide was changed was measured. The test oil used herein was the same as the test oil No. except for the amount of polyalkenylsuccinimide added. This is the same configuration as in FIG. When the addition amount of polyalkenyl succinimide was changed to 0.07% by weight in terms of nitrogen amount, iron (Fe) eluted with acid neutralizing ability
It was measured as an amount (in ppm) and is shown in FIG. When the amount of polyalkenyl succinimide added is 0.0
It can be seen that sulfuric acid corrosion is excellent when the content is 2% by weight, particularly 0.04% by weight or more.

[0028]

The lubricating oil for a diesel engine according to the present invention comprises (a) a highly basic calcium salicylate having a base number of 100 mgKOH / g or more in terms of calcium content of 0.0
4 to 0.2% by weight, (b) base number 100 mgKOH / g
Less than 0.01 to 0.1% by weight of low basic calcium salicylate as calcium and (c) 0.02% by weight of polyalkenyl succinimide as nitrogen
Or containing (a) a base number of 100 mgK
0.04 to 0.2% by weight of a high basic magnesium salicylate of OH / g or more as magnesium, and (b) 0.01 of a low basic calcium salicylate of less than 100 mg KOH / g as calcium. 0.1% by weight, and (c) 0.02% by weight or more of polyalkenyl succinimide in terms of nitrogen amount. ADVANTAGE OF THE INVENTION According to this invention, even if it is a lubricating oil for diesel engines with a relatively small ash content, it is excellent in clean dispersibility and corrosion and abrasion due to sulfuric acid can be suppressed.

[Brief description of the drawings]

FIG. 1 shows that when the amount of polyalkenylsuccinimide added was changed, the amount of iron (Fe) eluted from the acid neutralizing ability (ppm)
It is a figure showing the result of having measured as (unit).

Continued on the front page (51) Int.Cl. ⁷ Identification code FI C10N 20:00 C10N 20:00 Z 30:04 30:04 40:25 40:25

Claims (2)

(57) [Claims] 1. A mineral oil and / or a synthetic oil as a base oil,
(A) A highly basic calcium salicylate having a base number of 100 mgKOH / g or more is expressed as calcium in an amount of from 0.04 to
0.2% by weight, (b) 0.01 to 0.1% by weight of a low-basic calcium salicylate having a base number of less than 100 mg KOH / g as calcium, and (c) polynitroalkenyl succinimide as nitrogen. A lubricating oil for a diesel engine, characterized by containing 0.02% by weight or more. 2. A mineral oil and / or a synthetic oil as a base oil,
(A) A highly basic magnesium salicylate having a base number of 100 mg KOH / g or more is used in an amount of 0.04 as a magnesium amount.
(B) 0.01 to 0.1% by weight of a low-basic calcium salicylate having a base number of less than 100 mgKOH / g as calcium, and (c) polyalkenyl succinimide by nitrogen. A lubricating oil for diesel engines, characterized in that it contains at least 0.02% by weight.