JP2845497B2 - 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 even if it is present, this characteristic can be maintained 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 that (A) trivalent and pentavalent phosphate esters or Amine salts, 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]

In order to minimize the shift shock during shifting of an automatic transmission (automatic transmission) for an automobile, the present inventors have proposed a method for adjusting friction among various additives used in lubricating oil (ATF) for automatic transmission. From the viewpoint that it is important to select the agent (FM) and control the amount of the agent used, the intense study was conducted.

To prevent the FM in the ATF from being gradually consumed during use and causing a shift shock, it seems better to add a large amount of FM from the beginning, 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, and further by compounding a specific anti-wear agent, it was found that an ATF exhibiting excellent properties with time and temperature changes was obtained, and the present invention was completed. Reached.

[Means for solving the problem]

According to the present invention, in order to solve the above problems, a base oil
The following (i), (ii), (iii) and (iv), or (i), (iii) and (iv): (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 amine salts thereof; (ii) the following general formula (5) , (Wherein R ″, R, and R ′ represent a hydrogen atom, a C ₁ -C ₃₀ alkyl group, an aryl group, an alkyl-substituted aryl group or an alkanol group); (iii) aliphatic A lubricating oil composition characterized by comprising a dicarboxylic acid compound; and (iv) a primary zinc thiophosphate.

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 the 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, R ′ may be the same or completely different. When R ″, R, R ′ are exemplified, C ₁ -C ₃₀ alkyl And alkanol groups such as an alkyl-substituted aryl group, an ethanol group and a propanol group. Provided that at least one from the viewpoint of solubility in the oil is an alkyl group having C ₄ or higher chain lengths, it is desirable that the alkyl-substituted aryl group. (I
The following compounds are exemplified as specific compounds of i) component.

(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 exhibits strong adsorption activity at a high temperature. 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.

FM [(i) + (ii) + in the lubricating oil composition of the present invention
(Iii) or (i) + (iii)] is 0.01 to 2.
0 wt%, preferably 0.05 to 1.0 wt%. 0.01wt%
If the amount is less than the above, the effect as FM is insufficient, and a shift shock occurs. If the amount exceeds 2.0% by weight, as described above, too much FM is applied and slippage increases when the clutch is connected, which is not preferable.

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.

Next, the compounding of a specific antiwear agent, which is a feature of the present invention, will be described. Usually, this kind of lubricating oil contains an anti-wear agent, but in the present invention, as a composition for maintaining the anti-wear property and further improving the anti-wear property, the addition of primary zinc thiophosphate is preferable. Was found.

Zinc thiophosphate includes secondary zinc thiophosphate, but this composition has a strong adsorption power and inhibits the adsorption of FM to the friction surface. In addition, zinc allyl thiophosphate has a weak adsorptive power and is inferior in abrasion resistance.

The primary zinc thiophosphate used in the present invention exhibits an intermediate adsorption of the composition and has a friction reducing effect itself. Furthermore, it has the characteristic that it is harder to decompose than secondary zinc thiophosphate.

Examples of the primary zinc thiophosphate include those represented by the following general formula.

(In the above formula, R represents a C ₃ -C ₁₆ alkyl group.) The addition amount of the component (iv) is preferably 0.05 to 1.00 wt%, more preferably 0.10 to 0.50 wt%. . If it is less than 0.05 wt%, the wear resistance effect is low, and if it exceeds 1.00 wt%, FM adsorption can be prevented, μo / μd increases, and the wear characteristics deteriorate.

In the lubricating oil composition of the present invention, as the base oil to which the above-mentioned components are added, mineral oil and synthetic oil known in the art are used.

As mineral oils, 60 neutral oils, 100 neutral oils, 150 neutral oils by solvent refining or hydrorefining,
There are 300 neutral oils, 500 neutral oils, and low pour point base oils in which low-temperature fluidity is improved by removing wax components 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.

The lubricating oil composition of the present invention further comprises a secondary zinc thiophosphate, a metal detergent selected from zinc allyl thiophosphate, magnesium sulfonate, calcium sulfonate, etc., an succinimide, an ashless dispersant selected from benzylamine and the like, and a viscosity index. It may contain an improver, an antioxidant and the like.

〔Example〕

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 7 / Comparative Examples 1 to 3) As shown in Table 1 below, FM as a friction modifier was used.
Various changes were made to the components (i), (ii) and (iii) (total 0.5 wt%), the type of antiwear agent was changed, and the remaining base oil (refined mineral oil) , 4.0c
(St, 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, the ATF of the present invention, that is, an FM component having excellent stability against heat and oxidation and exhibiting strong adsorption activity on the low temperature side, and an FM component exhibiting adsorption activity on the high temperature side are combined in an appropriate amount, and are prepared. ATF with specific antiwear agent
In the test of friction characteristics using SAE No.2 testing machine,
It can be seen that there is little change over time and the friction coefficient is stable, and that the friction coefficient when measured while changing the oil temperature 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.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10M 137/02 C10M 137/02 137/04 137/04 137/08 137/08 137/10 137/10 A // C10N 10: 04 30:06 40:04 40:08 (72) Inventor Tatsuo Yoshioka 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (72) Inventor Isamu Kawaji 1-3-3 Nishi Tsurugaoka, Oimachi, Iruma-gun, Saitama Prefecture No. 1 in Tonen Co., Ltd. (72) Inventor Tadashi Sakakibara 1-3-1 Nishitsurugaoka, Oi-machi, Iruma-gun, Saitama Prefecture Tonen Co., Ltd. (56) References JP-A-49-53607 JP, A) JP-A-62-53398 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C10M 137/02-137/10 C10M 133/04-133/14 C10M 129 / 34 C10M 129/42

Claims (1)

(57) [Claims] (1) The base oil (i), (ii), (iii) and (iv) or (i), (iii) and (iv): (i) The following general formulas (1) and (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 amine salts thereof; (ii) the following general formula (5) , (Wherein R ″, R, and R ′ represent a hydrogen atom, a C ₁ -C ₃₀ alkyl group, an aryl group, an alkyl-substituted aryl group or an alkanol group); (iii) aliphatic A lubricating oil composition comprising a dicarboxylic acid compound; and (iv) a zinc zinc thiophosphate.