JPH04304299A - Lubricating oil composition - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in low-velocity slip performance and in durability by mixing a base oil with a specified metal sulfonate and a specified zinc long-chain-alkyl thiophosphate each in a specified amount. CONSTITUTION:A base oil is mixed with 0.1-10.0wt.% of at least one metal sulfonate selected from a metal alkylbenzenesulfonate of formula I (wherein R1 is 4-30C alkyl; R2 is H or 1-30C alkyl; M is Ca or Ba), a metal alkylsulfonate of formula II (wherein R3 and R4 are each independently 4-30C alkyl; M is Ca or Ba), and a metal alkylnaphthalenesulfonate of formula III (wherein R5 to R8 are each independently H or 1-30C alkyl; M is Ca or Ba); and 0.1-10.0wt.% of at least one zinc long-chain-alkyl thiophosphate of formula IV (wherein R1 to R4 are each independently 10-40C primary or secondary alkyl).

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to lubricating oil compositions. More specifically, the present invention relates to a lubricating oil composition for automatic transmissions, wet brake oils, etc., particularly for automatic transmissions of automobiles.

0002

2. Description of the Related Art Conventionally, two types of lubricating oil (hereinafter also referred to as ATF) have been used for automatic transmissions of automobiles.

One type of ATF is GM's Dexron II, which contains a friction modifier (hereinafter also referred to as FM) in the oil.
This is typified by oil that satisfies the standards. The other type is ATF that does not contain FM in the oil, and Ford's M
It is typified by oil that satisfies the 2C 33F (Type F) standard.

The type F ATF described above does not use FM, so it has the disadvantage that it causes a large shift shock during shifting, which worsens the ride comfort of the automobile.

[0005] Furthermore, the above-mentioned Dexron type II ATF
uses FM, so it has the characteristic that there is almost no shift shock when shifting, or even if there is, it is small, but this characteristic can be maintained only when the ATF is in a state close to new oil, and when the oil is heated As the FM deteriorates due to heat and oxidation, the FM is consumed and the shift shock becomes large.

On the other hand, generally when the ATF oil temperature is low,
For example, when you have just started driving or when driving in a cold region, the shift shock is significant even if the ATF is fresh oil. For this reason, various proposals have been made from the viewpoint of suppressing this type of shift shock that occurs when the ATF deteriorates or the oil temperature is low.
-173097, (A) trivalent and pentavalent phosphoric acid esters or amine salts thereof, and (B) sorbitan fatty acid esters, palm kernel oil fatty acids, coconut oil fatty acids (
The former two are mainly composed of higher fatty acid glycerin esters, that is, fats and oils. ), mixtures of oils and fatty acids,
Polyalkylene polyamines and fatty acids (or oxidized mineral oil)
A lubricating oil composition has been proposed, which contains one type of compound selected from the group consisting of a reaction product with. Furthermore, JP-A No. 63-254196 discloses that phosphoric acid ester, phosphorous ester,
It has been proposed to incorporate phosphate ester amine salts, carboxylic acids, carboxylic acid amides, etc. Furthermore, FM consisting of a condensation product of an unsaturated fatty acid and an alkanolamine was proposed in JP-A-63-180000, and FM consisting of a condensation product of a fatty acid and a dialkanolamine was proposed in JP-A-63-66299. FM consisting of a combination with fats and oils has been proposed, and JP-A-62-84190 proposes blending magnesium sulfonate with base oil as a metal detergent.

[0007]

[Problems to be Solved by the Invention] On the other hand, in recent years, lock-up clutches, which are effective in improving fuel efficiency, have been adopted in the torque converters of many automatic transmissions for automobiles. Conventionally, this lock-up mechanism operated only in high speed ranges and was not used in low speed ranges. Therefore, in low speed ranges such as when starting a car, when torque is transmitted by the torque converter, a power transmission loss occurs between the engine output speed and the transmission input speed, which reduces fuel efficiency. It was the cause. Therefore, in order to reduce this power transmission loss, it has recently been considered to operate the lock-up mechanism even in the low speed range of automatic transmissions.

However, when the lock-up mechanism is activated in the low speed range of an automatic transmission, abnormal vibrations accompanied by noise (shudder sound) caused by stick-slip often occur, so it is necessary to prevent the stick-slip from occurring. An ATF that can do this is required. Therefore, in the so-called "automatic transmission with slip control lockup" which operates the lockup clutch while slipping even in the low speed range, the generation of shudder noise is one of the important problems that must be solved. prevent such stick-slip,
In order to avoid the occurrence of shudder noise, ATF must have excellent low-speed sliding performance, that is, the friction coefficient increases as the sliding speed increases, and it must also have excellent sustainability (durability) of its low-speed sliding performance. It is considered important that However, there is still room for further improvement in conventional lubricating oils in order to satisfy the above-mentioned requirements in terms of low-speed sliding performance and durability.

[0009] Therefore, the present invention aims to provide a lubricating oil composition that has excellent low-speed sliding performance and also has excellent durability so that its performance does not deteriorate significantly even after long-term use. .

0010

[Means for Solving the Problems] According to the present invention, in order to solve the above problems, 0.1 to 10.0% by weight is added to the base oil.
(1), (2) and (3) below, (1) the following formula I,

[0011]

[C5]

[0012] [In the formula, R1 represents a C4-30 alkyl group, R2 represents hydrogen or a C1-30 alkyl group, and M represents Ca or Ba], (2 ) The following formula II,

[0013]

[C6]

[In the formula, R3 and R4 each independently represent a C4-30 alkyl group, and M is Ca or B
a] represents an alkyl sulfonic acid metal salt, (3
) The following formula III,

[0015]

[C7]

[In the formula, R5, R6, R7 and R8
each independently represents hydrogen or a C1-30 alkyl group, and M represents Ca or Ba. However, R5 and R6 or R7 and R8 are not hydrogen at the same time. Formula IV below in weight %,

[0017]

[Chemical formula 8]

[In the formula, R1, R2, R3 and R4
each independently represents a C10-40 primary or secondary alkyl group. Ru.

The sulfonic acid metal salt used in the present invention is
It is generally used as a metal detergent in lubricating oil compositions. Further, the long-chain alkylthiophosphate used in the present invention is generally used as an antiwear agent in lubricating oil compositions. In the present invention, the sulfonic acid metal salt and the long-chain alkylthiophosphate zinc are each contained in an amount of 0.1 to 10.0% by weight, particularly 1.0 to 4.0% by weight.
It has been unexpectedly discovered that when used in an amount of 0% by weight, it is possible to obtain a lubricating oil composition which has excellent low speed sliding performance and which is extremely durable.

[0020] If the amount of the sulfonic acid metal salt and zinc long-chain alkylthiophosphate is less than 0.1% by weight, the above-mentioned properties will be insufficient, and especially if the amount is 1.0% by weight or more, the above-mentioned properties will be insufficient. Significant improvement. This amount is 10.0% by weight
Even if it exceeds this value, no further improvement in properties can be obtained, and on the contrary, problems such as deterioration of wear resistance and increase in cost may occur.

In the alkylbenzenesulfonic acid metal salt of formula I, the alkyl group as R1 is C10-30
The alkyl group as R2 is preferably a C1-15 alkyl group. In the alkyl sulfonic acid metal salt of formula II, R
The alkyl group as 3 and R4 is preferably a C10-30 alkyl group. Further, in the alkylnaphthalene sulfonic acid metal salt of formula III, R5
, R6, R7 and R8 are preferably C10-20 alkyl groups. Moreover, it is preferable that at least one of R5 and R6 and at least one of R7 and R8 is a C10-20 alkyl group.

[0022] In the present invention, the sulfonic acid metal salt may be a so-called overbased salt in which fine particulate carbonate or the like is dispersed in the sulfonic acid metal salt; When a metal salt is used, it is desirable to mix it as a sulfonic acid metal salt in the above-mentioned amount.

In the long chain alkyl zinc thiophosphate of formula IV, alkyl as R1, R2, R3 and R4 is preferably a C12-30 primary alkyl group.

[0024] If short-chain zinc alkylthiophosphate is used instead of long-chain zinc alkylthiophosphate, the oily effect will be low when adsorbed to the surface of the friction material, and the low-speed sliding performance will be poor.

Base oils useful in the lubricating oil compositions of this invention can include mineral and synthetic oils known to those skilled in the art.

Mineral oils include 60 neutral oil, 100 neutral oil, and 15 neutral oil by solvent refining or hydrogenation refining.
There are 0 neutral oil, 300 neutral oil, 500 neutral oil, and low pour point base oil with improved low temperature fluidity by removing the wax content from these base oils.These base oils can be used alone or by mixing them in an appropriate ratio. use

Synthetic oils include polyα-olefin oligomers, diesters, polyol esters, polyglycol esters, etc. These base oils are usually used alone, but they can also be used in combination with the mineral oils mentioned above. You can also do it. The mixing ratio of synthetic oil and mineral oil is, for example, 80:2.
0 to 20:80.

In the present invention, the viscosity of the base oil described above is:
Preferably, it is 3 to 20 cSt at 100°C.

The lubricating oil composition of the present invention may optionally contain:
Even if anti-wear agents such as short chain alkylzinc thiophosphate and zinc allylthiophosphate, metal detergents such as magnesium sulfonate, ashless dispersants such as succinimide and benzylamine, viscosity index improvers and antioxidants are added. Amine-based, phosphoric acid ester-based and carboxylic acid-based friction modifiers may also be blended.

[0030]

[Examples] The present invention will be further explained below with reference to Examples, but the present invention is not limited in any way by these Examples.

Examples 1 to 9, Comparative Examples 1 to 6 Lubricating oil compositions having the compositions shown in Table 1 below were prepared.

A low speed sliding performance test was conducted on the obtained composition. The obtained results are also shown in Table 1.

[0033] Low-speed sliding performance was evaluated using an LVFA (low-speed sliding friction tester) under the following experimental conditions. The samples include oil at the time of preparation (new oil) and SAE No. 2 Friction tester (2000 cycles or 5000 cycles at oil temperature 120℃)
Two types of oil (degraded oil) that had been forcibly degraded through cycle operation were used. LVFA experimental conditions Disc: Paper-based material plate for domestically produced automatic transmissions:
Steel material pressing pressure for domestic automatic transmission: 10 Kgf
/cm2 Temperature: Under conditions of 40℃ or higher, the friction coefficient when the sliding speed is 2 cm/sec is μ2, and the friction coefficient when the sliding speed is 6 cm/sec is μ6.
It was measured as Here, the stick-slip resistance index is defined as μ2/μ6. It can be determined that the smaller the stick-slip resistance index is, the less stick-slip occurs, that is, the better the low-speed slip performance is.

[Table 1]

A1: Calcium dodecylbenzenesulfonate A2: Overbased calcium dodecylbenzenesulfonate (base number 400) A3: Barium hexadecylnaphthalenesulfonate B1
: Zinc dodecylthiophosphate B2: Zinc hexadecylthiophosphate C1: Zinc 2-ethylhexylthiophosphate D1: Stearylamine D2: Stearic acid D3: Sorbitan monooleate

From Table 1, it can be seen that the lubricating oil composition of the present invention has a small initial stick-slip resistance index and is excellent in low-speed sliding performance, and also has a small stick-slip resistance index even in degraded oil, and its change over time is extremely small. .

[0036]

[Effects of the Invention] The lubricating oil composition of the present invention has excellent low-speed sliding performance, excellent durability of low-speed sliding performance,
Even when a lock-up mechanism is employed in a low-speed range in an automatic transmission of an automobile, the ATF exhibits excellent characteristics such that stick-slip does not occur and therefore less noise is generated.

Claims (1)

[Claims] Claim 1: Base oil contains 0.1 to 10.0% by weight of the following (1), (2) and (3), (1) the following formula I, [Formula 1] [wherein R1 is C4 ~30 alkyl group, R2
represents hydrogen or a C1-30 alkyl group, M is C
a or Ba], (2) the following formula II, [Formula, R3 and R4 each independently represent C4-3
0 alkyl group, M represents Ca or Ba], (3) the following formula III, [wherein R5, R6, R7 and R8 are each independently Represents hydrogen or a C1-30 alkyl group, M
represents Ca or Ba. provided that R5 and R6 or R7 and R8 are not hydrogen at the same time];
at least one sulfonic acid metal salt selected from 0.
1 to 10.0% by weight of long-chain alkylthio of the following formula IV, [wherein R1, R2, R3 and R4 each independently represent a C10-40 primary or secondary alkyl group] A lubricating oil composition comprising a mixture with at least one zinc phosphate.