JPH06145680A - Lubricating oil composition - Google Patents

Abstract

PURPOSE:To obtain the subject new composition useful as a lubricating oil especially for inner combustion engine of automobile, having excellent frictional characteristics and wear resistance, improved solubility in base oil and less metal corrosion by adding a specific compound to a base oil. CONSTITUTION:A base oil (e.g. mineral oil such as 60 neutral oil or synthetic oil such as alpha-olefin oligomer) is blended with 0.07-5wt.% monoalkanolamine salt of an acidic phosphoric ester of the formula (R<1> is 14-22C alkyl or alkenyl; (m) is 0 or 1; (n) is 1 or 2) as a hard wearing agent and also as a friction adjustor based on the whole amount of the composition to give the objective composition. A monooleyl acidic phosphoric ester, a dioleyl acidic phosphoric ester or their mixture is preferable as the acidic phosphoric ester. For example, 3-amino 1,2-propanediol may be used as the monoalkanolamine to form a salt with the ester.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel lubricating oil composition, and more particularly, to excellent friction characteristics and wear resistance, good solubility in base oil, and low corrosiveness to metals. The present invention relates to a lubricating oil composition suitable for use as an internal combustion engine lubricating oil, a drive system lubricating oil, a gear oil, etc.

[0002]

2. Description of the Related Art Conventionally, lubricating oil has been used to smoothen the operation of internal combustion engines, drivetrain devices such as automatic transmissions, shock absorbers, power steering systems, and gears. It is well known that lubrication performance is insufficient under high load, and the lubricated surface rubs and wears, causing seizure. Therefore, for the purpose of reducing friction and wear and imparting good lubricity to the lubricating oil, an antiwear agent such as zinc dialkyldithiophosphate (ZnDTP) or a phosphorus-based antiwear agent / friction modifier is used. It is used. However, although the lubricating oil to which the ZnDTP is added has improved wear resistance, it has a drawback of having a high friction coefficient. Therefore, ZnDTP is usually used in combination with other additives in order to reduce the coefficient of friction, but in this case, the wear resistance is lowered due to the interaction with other coexisting additives, which is not desirable. Be invited. In order to solve this problem, for example, in a hydrocarbon base oil, Z
A hydraulic fluid composition for a shock absorber has been proposed in which an interaction between ZnDTP and an oily agent is prevented by adding an oily agent such as nDTP and a long-chain fatty acid and a detergent dispersant (Japanese Patent Laid-Open Publication No. Sho. 55-165996). However, although an oily agent such as a long-chain fatty acid used in combination has an effect of reducing the friction coefficient, it has a problem that it corrodes the bearing material of the shock absorber and promotes wear. On the other hand, examples of phosphorus-based antiwear agents and friction modifiers include aromatic phosphate esters, alkyl phosphate esters, and
Acid phosphate, amine salt of acid phosphate,
Phosphorous acid esters are known. Among these,
Although the acidic phosphoric acid ester has an excellent effect even if it is used in a small amount, it has a drawback that it is highly corrosive to metals. Therefore, an amine salt of an acidic phosphoric acid ester or a phosphorous acid ester is often used. However, conventional amine salts or phosphites of acidic phosphoric acid esters are not always sufficiently satisfactory in that they are inferior in abrasion resistance or inferior in effect as a friction modifier.

[0003]

Under the circumstances described above, the present invention is excellent in friction characteristics and wear resistance, has a good solubility in base oil, and has a low corrosiveness in metals. The present invention has been made for the purpose of providing a lubricating oil composition suitable for use as an internal combustion engine lubricating oil, a drive system lubricating oil, a gear oil, etc. for automobiles.

[0004]

DISCLOSURE OF THE INVENTION As a result of intensive studies to develop a lubricating oil composition having the above-mentioned preferable properties, the present inventors have found that a monoalkanolamine of a specific acidic phosphoric acid ester is added to a base oil. It was found that the composition can achieve the object by the composition in which the salt is added in a predetermined ratio, and the present invention has been completed based on this finding. That is, the present invention is based on the total weight of the composition for the base oil,

[0005]

[Chemical 2]

(Wherein R ¹ is an alkyl or alkenyl group having 14 to 22 carbon atoms, m is 0 or 1, and n is 1 or 2). The lubricating oil composition is characterized by containing 0.03 to 5.0% by weight. Hereinafter, the present invention will be described in detail. The base oil used in the lubricating oil composition of the present invention is not particularly limited, and those conventionally used as a base oil for lubricating oils such as mineral oil and synthetic oil are used.

Mineral oils include, for example, 60 neutral oil, 100 neutral oil by solvent refining or hydrogenating refining,
150 neutral oil, 300 neutral oil, 500
Examples thereof include neutral oils and low pour point base oils having improved low temperature fluidity by removing the wax content from these base oils. These may be used alone, or two or more kinds may be mixed in an appropriate ratio. You may use it. On the other hand, examples of synthetic oils include poly-α-olefin oligomers, diesters, polyol esters, polyglycol esters, and the like, and these base oils are usually used alone,
It can be used as a mixture with the mineral oil. The mixing ratio of the synthetic oil and the mineral oil is, for example, 80:20 to 20: by weight.
80. As the base oil used in the composition of the present invention, those having a viscosity at 100 ° C. in the range of 3 to 20 cSt are suitable. In the lubricating oil composition of the present invention, as the antiwear agent and friction modifier,

[0008]

[Chemical 3]

A monoalkanolamine salt of an acidic phosphoric acid ester represented by the formula (wherein R ¹ , m and n have the same meanings as described above) is used. R ¹ in the general formula [1] is an alkyl group or an alkenyl group having 14 to 22 carbon atoms, preferably 16 to 20 carbon atoms, n is 1 or 2, and the acidic phosphoric acid ester is a monoalkyl acidic phosphoric acid ester. It may be a dialkyl acidic phosphoric acid ester or a mixture thereof. Examples of such acidic phosphoric acid ester include mono- or dimyristyl acidic phosphoric acid ester, mono- or dipalmityl acidic phosphoric acid ester, mono- or distearyl acidic phosphoric acid ester, mono- or dioleylic acid phosphoric acid ester, mono- or dieicosyl acidic phosphoric acid ester. Esters and the like can be mentioned, and these may be used alone or in combination of two or more. Among the above-mentioned acidic phosphates, the number of carbon atoms is 16
~ 20 alkenyl groups, especially those having an oleyl group,
That is, monooleyl acid phosphoric acid ester, dioleic acid phosphoric acid ester and mixtures thereof are preferable.

The alkyl group or alkenyl group has 1 carbon atom.
Those having a carbon number of less than 4 have a low solubility in the base oil of the monoalkanolamine salt, and those having a carbon number of more than 22 have poor friction properties and wear resistance. On the other hand, as the monoalkanolamine which forms a salt with these acidic phosphoric acid esters, monoethanolamine when m is 0 and 3-amino-1,2-when m is 1 in the general formula [1]. Propanediol may be used, and these may be used alone or in combination. In the composition of the present invention, the monoalkanolamine salt of the acidic phosphoric acid ester represented by the general formula [1] is 0.07 to 5.0% by weight, preferably 0.1 to 10% by weight based on the total weight of the composition. 1.0% by weight
It is necessary to contain it in the ratio of. This amount is 0.0
If it is less than 7% by weight, a composition excellent in friction characteristics and abrasion resistance cannot be obtained, and if it exceeds 5.0% by weight, the effect is not improved for the amount and it is difficult to dissolve in the base oil. Become.

In the present invention, the monoalkanolamine salt of an acidic phosphoric acid ester may be separately prepared and added to the base oil, or the acidic phosphoric acid ester and the monoalkanolamine may be respectively added in an equivalent ratio. To form the amine salt in the base oil. The lubricating oil composition of the present invention contains various additives conventionally used in lubricating oils, such as metal detergents, ashless detergent dispersants, viscosity index improvers, and fluidizers, as long as the object of the present invention is not impaired. A point depressant, an antioxidant, a rust preventive, a corrosion inhibitor, an antifoaming agent, another antiwear agent, a friction modifier and the like can be appropriately added.

Examples of the metal detergent include calcium sulfonate, magnesium sulfonate, barium sulfonate, calcium phenate, barium phenate and the like, and these are usually used in a proportion of 0.1 to 5% by weight. As the ashless detergent dispersant, for example, succinimide type, succinamide type, benzylamine type,
Examples thereof include ester-based ones, and these are usually 0.
It is used in a proportion of 5 to 7% by weight. Examples of the viscosity index improver include polymethacrylate-based, polyisobutylene-based, ethylene-propylene copolymer system, styrene-butadiene hydrogenated copolymer system, etc., and these are usually contained in a proportion of 0.5 to 35% by weight. used. Examples of the antioxidant include amine-based antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine and alkylated-α-naphthylamine, 2,6-di-t-butyl-4-methylphenol, 4,4 ′. -Methylenebis (2,
6-di-t-butylphenol) and other phenolic antioxidants, which are usually used in a proportion of 0.05 to 2% by weight. Examples of the rust preventive agent include alkenyl succinic acid and its partial ester, examples of the corrosion inhibitor include benzotriazole and benzimidazole, and examples of the defoaming agent include dimethylpolysiloxane and polyacrylate. These can be added appropriately.

[0013]

EXAMPLES The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. Reference Example 1 The equivalent amount of monoethanolamine and 5 parts by weight of mineral oil base oil (100S
N) is mixed and heated at 120 ° C. for 5 minutes to obtain a preblend, which is diluted with mineral oil base oil so as to have the ratio shown in Table 1 and heated at 60 ° C. for 5 minutes. To prepare a composition. The following compositions were prepared in the same manner.
Solubility is measured by placing the composition in a 100 ml beaker at room temperature.
After standing for a day, it was visually determined.

[0014]

[Table 1]

Note 1) 0.0195 wt% as a phosphorus content 2) Equivalent to the amount of acidic phosphate ester added As can be seen from Table 1, the monoethanolamine salt of an acidic phosphate ester having an oleyl group used in the present invention is Although the solubility is good, the monoethanolamine salt of acidic phosphoric acid ester having an octyl group, a dodecyl group and a tridecyl group having less than 14 carbon atoms has poor solubility.

Examples 1 and 2 and Comparative Examples 1 to 10 Based on the total weight of the composition, based on the total weight of the composition, oleyl acid phosphoric acid ester (Pa) 0.3 wt% (phosphorus content 0.0195 wt%). ) And amines of the types shown in Table 2-1 were added at an equivalent ratio to the Pa to prepare a lubricating oil composition. The solubility, friction coefficient, and wear scar diameter of this composition were determined according to the following methods. The results are shown in Table 2-1. (1) Solubility Solubility was determined by the same method as in Reference Example 1 and evaluated according to the following criteria. ◯: Good Δ: A little bad ×: Poor (2) Friction coefficient, wear scar diameter load 40 kg, rotation speed 1800 rpm, test time 30 minutes,
Shell four-ball test (A at 90 ° C or 120 ° C oil temperature)
STM D-4172) was performed to determine the friction coefficient and wear scar diameter. From Table 2-1, monoethanolamine salt of oleyl acid phosphate used in the present invention and 3-
Each of the amino-1,2-propanediol salts has good solubility, and has a small friction coefficient and wear scar diameter.

Example 3 and Comparative Example 11 A composition in which oleyl acidic phosphoric acid ester (Pa) was added to a base oil (100 SN) in an amount shown in Table 2 based on the total weight of the composition, Pa and monoethanol. Amine (ME
A) and a composition added with the amounts shown in Table 2-2 and a composition added with Pa and 3-amino-1,2-propanediol (APD) in the amounts shown in Table 2-2 were prepared, Shell four-ball test (40 kg, 1800 rpm,
90 ° C. or 120 ° C. for 30 minutes) to determine the friction coefficient and wear scar diameter. The results are shown in Table 2-2. In addition,
The addition amount of each amine is equivalent to Pa. Example 4 and Comparative Examples 12 and 13 Base oil (100 SN) was added with dioleyl phosphite (Pi) and oleylamine salt of octyl acid phosphite (PaN) based on the total weight of the composition, respectively, as shown in Table 2-3. The composition added with the amount shown in was prepared, and the shell four-ball type test (40 kg, 1800 rpm, 9
0 ° C. or 120 ° C. for 30 minutes) to determine the friction coefficient and wear scar diameter. The results are shown in Table 2-3.

[0018]

[Table 2]

[0019]

[Table 3]

[0020]

[Table 4]

Note: Pa: oleyl acid phosphoric acid ester Pi: dioleyl phosphorous acid ester PaN: oleylamine salt of octyl acid phosphoric acid ester From Table 2, monoethanolamine salt of oleyl acid phosphoric acid ester used in the present invention and 3 -Amino-1,2-
It can be seen that the propanediol salt has good solubility and has a small friction coefficient and wear scar diameter in the shell four-ball test.

Examples 5 and 6 and Comparative Examples 14 and 15 Monoethanolamine salt of oleyl acid phosphate (Pa / MEA) and 3-amino-1,2 of oleyl acid phosphate were added to base oil (100 SN). A propanediol salt (Pa / APD), an oleyl acid phosphate ester (Pa) and an octyl acid phosphate oleylamine salt (PaN), each based on the total weight of the composition,
A lubricating oil composition was prepared by adding phosphorus to a concentration of 0.0195 wt% and further adding 0.3 wt% of a phenolic antioxidant. ISOT test (JISK-2514) for copper and steel test pieces for each composition
(According to the oxidation stability test method) was carried out under the conditions of 120 ° C. and 72 hours to determine the amount of change in metal weight. The result is the third
Shown in the table.

[0023]

[Table 5]

Note: Pa: oleyl acidic phosphoric acid ester Pa / MEA: monoethanolamine salt of oleyl acidic phosphoric acid ester Pa / APD: 3-amino-1,2-propanediol salt of oleyl acidic phosphoric acid ester PaN: octyl Oleylamine salt of acidic phosphoric acid ester

[0025]

EFFECTS OF THE INVENTION According to the present invention, a lubricating oil composition having excellent friction characteristics and wear resistance, good solubility in base oil, and low corrosiveness to metal can be obtained. The lubricating oil composition of the present invention is particularly suitable for use as an internal combustion engine lubricating oil, a drive system lubricating oil, a gear oil, etc. for automobiles.

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Claims (1)

[Claims] 1. Based on the total weight of the composition based on the base oil, a compound of the general formula: (R ¹ in the formula is an alkyl group or an alkenyl group having 14 to 22 carbon atoms, m is 0 or 1, and n is 1 or 2) monoalkanolamine salt of acidic phosphoric acid ester 0.07 to A lubricating oil composition comprising 5.0% by weight.