JP2845498B2 - Lubricating oil composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lubricating oil composition, and more particularly to a lubricating oil composition for use in automatic transmissions and wet brake oils, particularly for automatic transmissions in automobiles.

[Conventional technology]

Conventionally, two types of lubricating oils (hereinafter, also referred to as ATFs) for automatic transmissions of automobiles have been used.

One is an ATF in which a friction modifier (hereinafter, also referred to as FM) is blended in the oil, which is represented by an oil which satisfies GM's Dexlon II standard. Others are ATFs that do not contain FM in the oil, such as those that meet Ford's M2C 33F (Type F) standard.

The above-mentioned type F ATF does not use FM, so that there is a large shift shock at the time of shifting, which has a disadvantage of deteriorating the riding comfort of the vehicle.

Also, since the above-mentioned Dexlon II type ATF uses FM, there is almost no shift shock at the time of shifting,
Although it has a small characteristic, this characteristic can be sustained only when the ATF is close to new oil, and if the oil deteriorates due to heat or oxidation, the FM will be consumed and the gear will be changed. Shock increases.

On the other hand, in general, when the oil temperature of the ATF is low, for example, when the vehicle has just started traveling, or when traveling in a cold region,
Even if ATF is new oil, the shift shock is large. Various proposals have been made from the viewpoint of suppressing this type of shift shock. For example, JP-A-60-173097 discloses (A) trivalent and pentavalent phosphate esters or amine salts thereof, and (B) ) Sorbitan fatty acid esters, palm kernel oil fatty acids,
Coconut oil fatty acids (the former two are glycerin esters of higher fatty acids, that is, oils and fats as main components), a mixture of oils and fats, a reaction product of a fatty acid of polyalkylene polyamine (or oxidized mineral oil), There has been proposed a lubricating oil composition containing one compound selected from the group consisting of: JP-A-63-254196 discloses that a specific base oil is FM
It has been proposed to mix phosphates, phosphites, phosphate amine salts, carboxylic acids, carboxylic amides, and the like. Further, JP-A-63-1800
No. 00 proposes an FM comprising a condensation product of an unsaturated fatty acid and an alkanolamine, and JP-A-63-66299 discloses an FM comprising a combination of a reaction product of a fatty acid and a dialkanolamine and a fatty acid or a fat or oil. Has been proposed and
62-84190 proposes the incorporation of magnesium sulfonate as a metal detergent into a base oil.

Including these proposals, it has been studied to obtain a stable lubricating oil for an automatic transmission of an automobile that does not cause a shift shock for a long period of time. There is still room for improvement.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION In order to minimize shift shock during shifting of an automatic transmission for an automobile (automatic transmission), the present inventors have developed a friction modifier among various additives used for lubricating oil (ATF) for automatic transmission. From the viewpoint that it is important to control the selection of (FM) and its usage, we conducted intensive studies.

It seems that it is better to add a large amount of FM from the beginning to prevent the FM in the ATF from gradually exhausting during use and causing shift shock, but if too much FM is added, the friction coefficient will increase. Is small, slippage increases when the clutch is engaged, and the shift time is prolonged. This is not preferable because the response is deteriorated, causing a feeling of skipping and an engine idle. Therefore, it is important to select an FM that is less likely to be consumed under high-temperature operation, in other words, has excellent stability against heat and oxidation, against the problem of shift shock due to the consumption of FM.

In addition, for the problem of shift shock when the ATF oil temperature is relatively low, the change in the friction coefficient with respect to the temperature change is small.
It is important to use ATF.

With the above in mind, the present inventors have a strong adsorption activity at low temperatures, that is, one or two types of FM that improve friction characteristics at lower temperatures, and a strong adsorption activity at high temperatures, that is, higher temperatures. One type of FM that improves friction characteristics on the side
By combining three types of FM, it has been found that an ATF exhibiting excellent characteristics over time and temperature can be obtained, and the present invention has been completed.

[Means for solving the problem]

According to the present invention, in order to solve the above-mentioned problems, (i) the following general formulas (1), (2), (3) and (4): (In the above formula, l represents an integer of 1 or 2, m and n each represent an integer of 1 or 2, R and R ′ may be the same or different, and each represents C ₄ to alkyl C _30, acidic phosphoric acid ester represented by an aryl group or an alkyl-substituted aryl group), acid phosphite and at least one selected from an amine salt thereof, (ii) the following general formula (5) , Wherein R ″, R, R ′ represent a hydrogen atom, a C ₁ -C ₃₀ alkyl group, an aryl group, an alkyl-substituted aryl group or an alkanol group, and (iii) a fatty acid The present invention provides a lubricating oil composition characterized by comprising an aliphatic dicarboxylic acid compound represented by the formula:

The first FM (i-component) constituting the lubricating oil composition of the present invention comprises an acidic phosphoric acid ester or an acidic phosphorous acid represented by the general formulas (1), (2), (3) and (4). At least one selected from acid esters and their amine salts, this FM exhibits a strong adsorption activity (a property of adsorbing to a friction surface that generates friction and lowering the friction coefficient between them) at a low temperature. Specific compounds of this type include, for example, R is butyl, hexyl, octyl, decyl, lauryl, myristyl, palmityl, stearyl, oleyl,
Mono (R) phosphates such as phenyl and cresyl,
Acidic phosphoric acid esters such as di (R) phosphate; acidic phosphites such as mono (R) phosphite and di (R) phosphite; R is as described above, and R 'is as defined above. Acidic phosphate ester ein salts such as di (R) phosphate mono (R ') amine salts and mono (R) phosphatedi (R') amine salts, excluding phenyl and cresyl (aryl groups); (R) Acid phosphite amine salts such as phosphite amine salts.

Next, the second FM (ii) constituting the lubricating oil composition of the present invention
Component) is composed of an alkylamine compound represented by the general formula (5). The FM (ii) component also has a strong adsorption activity at a low temperature (adsorbs to a friction surface that produces friction, and a friction coefficient between the two). (A characteristic of lowering the temperature). In formula (5), two or three of R ″, R and R ′ may be the same or completely different.

R ", R, To illustrate R ', C ₁ ~C ₃₀ alkyl group,
Examples include an alkanol group such as an alkyl-substituted aryl group, an ethanol group, and a propanol group. However, from the viewpoint of solubility in oil, it is preferable at least one is an alkyl group or an alkyl-substituted aryl group having C ₄ or higher chain length. Specific examples of the compound (ii) include the following.

(A) Monoamines Examples thereof include butylamine, pentylamine, hexylamine, octylamine, laurylamine, octadecylamine, oleylamine, and stearylamine.

(B) Diamines For example, dibutylamine, dipentylamine, dihexylamine, dioctylamine, dilaurylamine, dioctadecylamine, distearylamine, stearyl monoethanolamine, palmityl monopropanolamine, decyl monoethanolamine, hexyl・
Monopropanolamine, phenyl / monoethanolamine, tolyl / monopropanolamine and the like are exemplified.

(C) Triamines For example, tributylamine, tripentylamine, trihexylamine, trioctylamine, trilaurylamine, trioctadecylamine, trioleylamine, tristearylamine, dioleyl monoethanolamine, dilauryl monopropanolamine, dioctyl. Monoethanolamine, dihexyl monopropanolamine, dibutyl monopropanolamine,
Oleyl diethanolamine, stearyl dipropanolamine, lauryl diethanolamine, octyl dipropanolamine, butyl diethanolamine, phenyl diethanolamine, tolyl dipropanolamine, xylyl diethanolamine, diethanolamine, dipropanolamine and the like are exemplified.

Next, the third FM (ii) constituting the lubricating oil composition of the present invention
The component i) is an aliphatic dicarboxylic acid compound, and the FM component has a strong adsorptive power and a good stability when compared with, for example, an aliphatic monocarboxylic acid, and exhibits a strong adsorptive activity particularly at a high temperature side. is there. Specific compounds of this type include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid (brassic acid), dodecandioic acid, tetradecandioic acid, octadecandioic acid, eicosanedioic acid, tria Examples include contanedioic acid and the esterification reaction products of these dicarboxylic acids or anhydrides thereof with diethylene glycol, thiodiethylene glycol or monoalkylene glycol.

The present inventors have not fully clarified the mechanism by which the combination of FM used in the present invention exerts an excellent effect, but speculate as follows. That is, by using FM (component i) and component (ii) exhibiting strong adsorption activity on the low-temperature side in combination with FM (component iii) exhibiting strong adsorption activity on the high-temperature side, the amine on the adsorption surface itself Because it has a strong adsorption power and is even more basic,
Adsorption of acidic FM (acidic phosphate, acidic phosphite or its amine salt) and aliphatic carboxylic acid is promoted, and the adsorption state of FM is stabilized. It is presumed that this increases the friction adjustment effect.

FM [(i) + (ii) + in the lubricating oil composition of the present invention
(Iii)] is added in an amount of 0.01 to 2.0 wt%, preferably 0.05 to 2.0 wt%.
~ 1.0wt% is blended. If it is less than 0.01 wt%, the effect as FM will be insufficient, and a shift shock will occur.
%, It is not preferable because slippage increases when the clutch is connected due to excessive FM input as described above.

Further, in the lubricating oil composition of the present invention, the FM
The mixing ratio of [(i) + (ii)] component and FM (iii) component is 1
0: 90 ~ 90: 10% effective by weight, but 25: 75 ~
It is effective to use 75: 25% by weight. Further, the mixing ratio of the FM (i) component and the FM (ii) component is 10: 9.
It shows effects in a wide range of 0-90: 10% by weight, but 25: 75-75:
It is effective to use 25% by weight. Meanwhile, FM
In the case of component (i) and component FM (iii), the mixing ratio is 2
It shows an effect in a wide range from 0:80 to 80: 20% by weight, but 40: 60 ~
It is most effective to use 60: 40% by weight.

In the lubricating oil composition of the present invention, the above-mentioned FM (i),
The base oils to which the components (ii) and (iii) are added include:
Mineral oils and synthetic oils known in the art are used.

Mineral oils include 60 neutral oils, 100 neutral oils, 150 neutral oils, 30 neutral oils by solvent refining or hydrorefining.
There are 0 neutral oil, 500 neutral oil, and a low pour point base oil in which low-temperature fluidity is improved by removing a wax component from these base oils, and these are used alone or in a mixture at an appropriate ratio.

Examples of synthetic oils include poly-α-olefin oligomers, diesters, polyol esters, polyglycol esters, and the like. These base oils are usually used alone, but may be used as a mixture with the above-described mineral oil. The mixing ratio between the synthetic oil and the mineral oil is, for example, 80:20 to 20:80.

In the present invention, the viscosity of the aforementioned base oil is preferably 3 to 20 cSt at 100 ° C.

Lubricating oil composition of the present invention, primary zinc thiophosphate, secondary zinc thiophosphate, antiwear agent and magnesium detergent selected from zinc allyl thiophosphate, metal detergent and succinimide selected from calcium sulfonate and the like,
It may contain an ashless dispersant selected from benzylamine and the like, as well as a viscosity index improver and an antioxidant. [Examples] Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited to these examples.

(Examples 1 to 14 / Comparative Examples 1 to 12) As shown in Table 1 below, FM as a friction modifier was used.
The components (i), (ii), (iii), (IV) and (V) (total 0.5 wt%) were variously changed, and the remaining base oil (refined mineral oil, refined mineral oil, Four.
0cSt, 100 ° C) to prepare test oils.

The friction characteristics of the test oil thus adjusted were measured using a SAE No. 2 friction tester manufactured by Automax (Japan).

This test consists of a dynamic test and a static test.
The torque values Td (dynamic friction torque), To (final friction torque), and Ts (static friction torque) are obtained from the torque curves obtained in each test, and based on the following equation (1), Friction coefficient μd (dynamic friction coefficient), μo
(Final friction coefficient) and μs (static friction coefficient) were calculated. The results are shown in Table 1.

From Table 1, it can be seen that the ATF of the present invention, that is, two kinds of FM components having excellent stability to heat and oxidation and exhibiting strong adsorption activity on the low temperature side, and one kind of FM component exhibiting adsorption activity on the high temperature side
The ATF prepared by combining the appropriate amounts of the components showed that the friction coefficient was stable with little change over time and the friction coefficient was stable in the test of friction characteristics using the SAE No. 2 It can be seen that the friction coefficient is also stable.

〔The invention's effect〕

The lubricating oil composition of the present invention has excellent characteristics that the change in friction coefficient with time is small and stable, and the change in friction coefficient with oil temperature change is small. Therefore, it is particularly useful as a lubricating oil for an automatic transmission of an automobile, and in a shift shock sensitivity test on an actual vehicle, a shift shock at the time of shift is suppressed, so that riding comfort is extremely good.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10M 137/02 C10M 137/02 137/04 137/04 137/08 137/08 // C10N 30:06 40:04 40:08 (56) References JP-A-49-53607 (JP, A) JP-A-62-53398 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C10M 137/02-137 / 08 C10M 133/04-133/14 C10M 129/34 C10M 129/42

Claims (1)

(57) [Claims] 1. A base oil comprising: (i) the following (1), (2), (3) and (4): (In the above formula, l represents an integer of 1 or 2, m and n each represent an integer of 1 or 2, R and R ′ may be the same or different, and each represents C ₄ to alkyl C _30, acidic phosphoric acid ester represented by an aryl group or an alkyl-substituted aryl group), acid phosphite and at least one selected from an amine salt thereof, (ii) the following general formula (5) , Wherein R ″, R, R ′ represent a hydrogen atom, a C ₁ -C ₃₀ alkyl group, an aryl group, an alkyl-substituted aryl group or an alkanol group, and (iii) a fatty acid A lubricating oil composition characterized by comprising an aromatic dicarboxylic acid compound.