JPH07197067A - Lubricating oil composition for diesel engine - Google Patents

Abstract

PURPOSE:To obtain the subject composition excellent in wear resistance, oxidation stability and high-temperature cleaning and dispersing properties and capable of improving the cleanliness of the area near the piston of a diesel engine and the high-temperature wear resistance of its sliding parts. CONSTITUTION:This composition is prepared by mixing a lubricating base oil with 0.1-5wt.%, based on the total weight of the composition, polyalkenylsuccinimide of a number-average molecular weight of 500 or above and/or its adduct to boron, 0.1-7wt.% zinc dialkyl dithiophosphate having a 1-30 C hydrocarbon groups and a prim. alkyl/sec. alkyl weight ratio of 50:50 to 95:5 and a mixture comprising 0.5-5wt.% overbasic calcium phenate, 0.5-5wt.% overbasic calcium sulfonate and 0.5-5wt.% neutral calcium sulfonate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel diesel engine lubricating oil composition, and more particularly to a diesel engine lubricating oil composition having excellent wear resistance, oxidation stability and high temperature clean dispersibility. .

[0002]

2. Description of the Related Art In recent years, high-performance engines have been required as automobiles have become faster, and in diesel engines, not only the piston periphery but also the sliding parts have considerably higher temperatures than conventional diesel engines. Has become. Therefore, it is necessary to improve the cleanliness of the lubricating oil used around the piston and the wear resistance at high temperatures for each sliding part. Conventionally, as a diesel engine lubricating oil, for example, a solid impurity cohesive diesel engine oil (Japanese Patent Publication No. 3-29839) having a composition obtained by adding calcium phenate, magnesium sulfonate and alkenyl succinimide to mineral oil or synthetic oil.
A heavy-duty diesel lubricating oil (JP-A-1-163294) in which a base oil contains (A) an ashless dispersant, (B) a sulfurized alkylphenol and (C) an organic sulfur compound has been proposed. However, although the respective desired purposes have been achieved by the combination of these additives, the cleanliness and high temperature wear resistance in the piston peripheral portion and each sliding portion as described above cannot be sufficiently satisfied. There is a problem.

[0003]

Under the above circumstances, the present invention provides a lubricating oil agent for diesel engines,
The object of the present invention is to provide a lubricating oil composition capable of improving the cleanliness of the piston peripheral part and the high temperature wear resistance of each sliding part.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies to develop a lubricating oil composition for diesel engines having the above-mentioned preferable properties, and as a result, have found that a specific number of lubricating oil base oils has been obtained. Polyalkenyl succinimide or boron adduct having a molecular weight, zinc dialkyldithiophosphate having a ratio of primary alkyl group to secondary alkyl group within a specific range, and overbased calcium phenate and overbased calcium sulfonate And a neutral calcium phenate in a predetermined ratio each, a lubricating oil composition having excellent wear resistance, oxidative stability and high temperature detergent dispersibility, and suitable for the above purpose. Based on this finding, the present invention has been completed. That is, the present invention is based on the total weight of the composition based on the lubricating base oil (A)
A polyalkenyl succinimide having a number average molecular weight of 500 or more and / or its boron adduct of 0.1 to 5% by weight,
(B) Zinc dialkyldithiophosphate having a hydrocarbon group having 1 to 30 carbon atoms and having a weight ratio of primary alkyl group to secondary alkyl group of 50:50 to 95: 5 is 0. 0.1 to 7% by weight, and (C) (a) overbased calcium phenate, (b) overbased calcium sulfonate and (c) neutral calcium sulfonate respectively.
The present invention provides a lubricating oil composition for a diesel engine, which contains 5 to 5% by weight.

The present invention will be described in detail below. As the base oil used in the composition of the present invention, a mineral oil or a synthetic oil conventionally used as a base oil of a lubricating oil is used. As the mineral oil, for example, a raffinate obtained by solvent refining using an aromatic extraction solvent such as phenol or furfural as a lubricating oil raw material, or silica-alumina as a raw material for the raw material, and hydrogenation using cobalt or molybdenum as an active ingredient. Lubricating oil fractions derived from hydrotreated oils obtained by hydrotreating using a treatment catalyst, such as light neutral oil, medium neutral oil, heavy neutral oil, bright stock, and the like can be mentioned. On the other hand, as the synthetic oil, for example, poly α-olefin oligomer,
Polybutene, alkylbenzene, polyol ester,
Examples thereof include polyglycol ester, dibasic acid ester, phosphoric acid ester, silicone oil and the like. These base oils may be used alone or in combination of two or more kinds, and mineral oil and synthetic oil may be mixed and used. As the base oil, one having a kinematic viscosity at 100 ° C. of usually 3 to 20 mm ² / s is suitable.

In the composition of the present invention, a polyalkenyl succinimide and / or its boron adduct having a number average molecular weight of 500 or more is used as the component (A). Examples of the polyalkenyl succinimide include those represented by the general formula:

[Chemical 1] (In the formula, R ¹ is an olefin oligomer residue having 30 or more carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, and m is 1 to 1.
Which is an integer of 0), and a general formula

[Chemical 2] (R ³ and R ⁴ in the formula are each an olefin oligomer residue having 30 or more carbon atoms, and they may be the same or different, and R ⁵ and R ⁶ are each 2 to 2 carbon atoms.
4 alkylene groups, which may be the same or different from each other, and n is 0 or an integer of 1 to 10).
And a bispolyalkenylsuccinimide represented by

In the present invention, as the polyalkenyl succinimide, either a mono-form or a bis-form can be used, but a mixture thereof is preferable. The mixing ratio of the monopolyalkenyl succinimide and the bispolyalkenyl succinimide is preferably 80: 2 by weight.
It is in the range of 0 to 20:80, more preferably 60:40 to 40:60. By setting the mixing ratio within this range, sludge dispersibility at high temperature is improved. In accordance with the present invention, polyalkenyl succinimide boron adducts are particularly preferred, and high molecular weight boron-based polyalkenyl succinimides are preferred, as described below. These polyalkenyl succinimides can be produced by reacting a polyalkenyl succinic anhydride, which is usually obtained by reacting a polyolefin with maleic anhydride, with a polyalkylene polyamine. The mono- and bis-forms of the polyalkenyl succinimide can be produced by changing the reaction ratio of the polyalkenyl succinic anhydride and the polyalkylene polyamine.
In the production of the polyalkenyl succinimide, the polyolefin used as a raw material has 2 to 2 carbon atoms.
Carbon number of 30 or more obtained by polymerizing 6 olefins,
It is preferably 40 or more and has a number average molecular weight of 500 to 2
The one used is 000, preferably 5,000 to 13,000. The number average molecular weight is a value expressed in terms of polystyrene. Also, the weight average molecular weight / number average molecular weight (Mw / Mn) is 1.5 to 4.0, preferably 1.8.
Those in the range of to 3.0 are preferable. If Mw / Mn is less than 1.5 or exceeds 4.0, sludge dispersibility is not sufficiently exhibited. Moreover, as an olefin monomer which forms polyolefin, 1 type (s) or 2 or more types of C2-C8 alpha olefin can be mixed and used. On the other hand, examples of the polyalkylene polyamine include polyethylene polyamine, polypropylene polyamine, polybutylene polyamine, and the like. Among these, polyethylene polyamine is preferable. The boron adduct of polyalkenyl succinimide can be produced by a conventional method. The content of boron in this boron adduct is in the range of 0.1 to 5% by weight, and the preferred content is in the range of 0.1 to 2% by weight.

In the composition of the present invention, the polyalkenyl succinimide and / or its boron adduct as the component (A) is 0.1 to 5% by weight, preferably 0.15 to 10% by weight based on the total weight of the composition. It is necessary to blend in the range of 3% by weight. When the content is less than 0.1% by weight, the sludge dispersibility at high temperature is not sufficient, while when it exceeds 5% by weight, the effect cannot be improved in the ratio of the amount added. The sludge dispersibility at high temperature can be further improved by using a boron adduct having excellent heat resistance. In the composition of the present invention, zinc dialkyldithiophosphate having a hydrocarbon group having 1 to 30 carbon atoms is used as the component (B). This zinc dialkyldithiophosphate has the general formula

[Chemical 3] Is a compound represented by. In the above general formula [3],
R ^{7 to} R ¹⁰ are each a hydrocarbon group having 1 to 30 carbon atoms, and they may be the same or different. Examples of the hydrocarbon group include primary alkyl groups having 1 to 30 carbon atoms, preferably 4 to 20 carbon atoms, more preferably 6 to 18 carbon atoms, and 3 to 30 carbon atoms, preferably 4 to 20 carbon atoms, and more preferably 5 carbon atoms. To a secondary alkyl group having 15 to 15 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an alkylaryl group having 7 to 30 carbon atoms.

In the present invention, the zinc dialkyldithiophosphate used as the component (B) has a weight ratio of the primary alkyl group to the secondary alkyl group of 50:50 to 95: It should be in the range of 5, preferably 60:40 to 90:10. Such zinc dialkyldithiophosphate acts not only as an antiwear agent that improves the wear resistance at low temperatures and high temperatures, but also as an antioxidant. To prepare zinc dialkyldithiophosphate having a ratio of primary alkyl group to secondary alkyl group in the above range, (1) dialkyldithiophosphorus in which R ^{1 to} R ⁴ are all primary alkyl groups A method of mixing at least one zinc acid salt with at least one zinc dialkyldithiophosphate in which R ^{1 to} R ⁴ are all secondary alkyl groups,
(2) Method using one or more zinc dialkyldithiophosphates having a primary alkyl group and a secondary alkyl group in the molecule (3) Dialkyldithiophosphorus in which R ^{1 to} R ⁴ are all primary alkyl groups A method of mixing at least one zinc acid salt with at least one zinc dialkyldithiophosphate having a primary alkyl group and a secondary alkyl group in the molecule, and (4) R ¹
~ One or more zinc dialkyldithiophosphates in which R ⁴ are all secondary alkyl groups and one or more zinc dialkyldithiophosphates having a primary alkyl group and a secondary alkyl group in the molecule are mixed. A method can be mentioned.

In the composition of the present invention, the zinc dialkyldithiophosphate as the component (B) is blended in the range of 0.1 to 7% by weight, preferably 0.3 to 5% by weight based on the total weight of the composition. It is necessary to. If the content is less than 0.1% by weight, the sufficient wear resistance effect is not exhibited, and if it exceeds 7% by weight, the wear resistance effect is not improved in accordance with the increase in the addition amount. In the composition of the present invention, as the component (C), a metal detergent comprising a combination of (a) overbased calcium phenate, (b) overbased calcium sulfonate and (c) neutral calcium sulfonate is used. As the overbased calcium phenate as the component (a), an alkylphenate having an alkyl group having a base number of 200 or more and 1 to 50 carbon atoms is preferably used, and as the overbased calcium sulfonate as the component (b). Is preferably an alkylbenzene sulfonate having an alkyl group having a base number of 200 or more and a carbon number of 1 to 50. By combining the three kinds of metal detergents in this way, it is possible to secure the cleanability in a wide area.
In the composition of the present invention, the metal detergent as the component (C) may be added in an amount of 0.5 to 5% by weight, preferably 0.8 to 3% by weight, based on the total weight of the composition. is necessary. If the content is less than 0.5% by weight, the desired detergency cannot be obtained. On the other hand, if it exceeds 5% by weight, the detergency cannot be significantly improved. The three types of metal detergents (a), (b) and (c) above are used in a substantially equal amount on a weight basis in order to appropriately exhibit their respective characteristics.
Specifically, it is preferable to set in the range of 1: 0.75 to 1.25: 0.75 to 1.25.

In the lubricating oil composition of the present invention, if necessary, other antiwear agents, friction reducing agents, antioxidants, viscosity index improvers, pour point depressants, rust preventives, antifoaming agents, corrosion agents, etc. An inhibitor or the like can be appropriately added and used. Other antiwear agents include, for example, sulfur compounds, phosphoric acid esters, phosphorous acid esters, amine salts of phosphoric acid esters, amine salts of phosphorous acid esters, etc. It is used in a proportion of 05 to 5.0% by weight, and examples of the friction reducing agent include amine-based and phosphoric acid ester-based agents, which are usually added in a proportion of 0.05 to 5.0% by weight. used. Examples of the antioxidant include amine-based antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine, and alkylphenyl-α-naphthylamine, 2,6-ditertiarybutylphenol, 4,4′-methylenebis- ( 2,6-ditertiary butylphenol) and the like phenolic antioxidants, etc., and these are usually 0.0
It is used in a proportion of 5 to 2.0% by weight. Examples of the viscosity index improver include polymethacrylate-based, polyisobutylene-based, ethylene-propylene copolymer system, styrene-butadiene hydrogenated copolymer system and the like, and these are usually contained in a proportion of 5 to 35% by weight. used. Further, examples of the rust preventive agent include alkenyl succinic acid and its partial ester, and examples of the defoaming agent include dimethylpolysiloxane and polyacrylate.

[0012]

EXAMPLES The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. The performance of the lubricating oil composition was determined according to the method described below. (1) JASO Detergency Determined in accordance with JASO M336 SD-22. (2) Wear resistance A wear resistance was obtained by measuring the wear scar diameter by a shell four-ball wear resistance test under the following conditions. Load: 40 kg Oil temperature: 60 ° C, 120 ° C Rotation speed: 1800 rpm Test time: 30 minutes

Example 1 Solvent refined oil 1 having a kinematic viscosity at 100 ° C. of 5.3 mm ² / s 1
0W-30, based on the total weight of the composition, a boron-based polyalkenyl succinimide (number average molecular weight of 8,000
0) 4% by weight, a mixture of primary zinc dioctyldithiophosphate and secondary zinc zinc diethylbenzyldithiophosphate (weight ratio 1: 0.7) 3% by weight, overbased calcium phenate (base number 300 2% by weight, 2% by weight of overbased calcium sulfonate (base number 300), 2% by weight of neutral calcium sulfonate, 0.5% by weight of phenolic antioxidant, non-dispersion type OCP viscosity index improver 7% by weight, polymethacrylate-based pour point depressant 0.02
% By weight and 0.002% by weight of silicone antifoaming agent were added to prepare a lubricating oil composition for diesel engines. The performance of this composition is shown in Table 1. Example 2, Comparative Examples 1 to 6 Based on the total weight of the composition, the components of the types and amounts shown in Table 1 were added to the lubricating base oil 10W-30, and other components were added in the same manner as in Example 1. The components were added to prepare a diesel engine lubricating oil composition. The performance of each composition is shown in Table 1. The number average molecular weight of the polyalkenyl succinimide in the table is 8,000.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

EFFECT OF THE INVENTION The lubricating oil composition for diesel engines of the present invention is excellent in wear resistance, oxidative stability and high temperature clean dispersibility, cleanliness of the periphery of the piston of the diesel engine and high temperature wear resistance of each sliding part. The sex can be improved.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location C10M 159: 24 135: 10 139: 00) A C10N 10:04 20:04 30:04 30:06 30:10 40:25

Claims (1)

[Claims] 1. A lubricating base oil, based on the total weight of the composition,
(A) a polyalkenyl succinimide having a number average molecular weight of 500 or more and / or its boron adduct of 0.1 to 5% by weight, and (B) a hydrocarbon group having 1 to 30 carbon atoms,
The weight ratio of the primary alkyl group to the secondary alkyl group is 50: 5.
0.1 to 7% by weight of zinc dialkyldithiophosphate in the range of 0 to 95: 5, and (C) (a) overbased calcium phenate, (b) overbased calcium sulfonate and (c) A lubricating oil composition for diesel engines, which contains 0.5 to 5% by weight of soluble calcium sulfonate.