JPH05163496A - Automatic transmission fluid composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent friction control function and thermal oxidation stability, capable of lightening and miniaturing automatic transmission for automobile, by blending a base oil of lubricating oil composed of a mineral oil, a synthetic oil or a mixed oil thereof with a specific calcium salicylate. CONSTITUTION:A base oil of lubricating oil composed of a mineral oil, a synthetic oil or a mixed oil thereof is blended with 0.01-5.0wt.% at least one of calcium salicylates of formula I (R is >=6C alkyl; M is Ca) and formula II and optionally an antioxidant (e.g. diphenylamine), a dispersant (e.g. succinic acid amide), a wear inhibitor (e.g. tricresyl phosphate), a metal inactivating agent (e.g. benzotriazole), a friction coefficient adjuster (e.g. cetylamine), a defoamer (e.g. dimethylpolysiloxane) and a viscosity index improver (e.g. polymethacrylate) to give the objective automatic transmission fluid composition having excellent friction control function and thermal oxidation stability.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a lubricating oil composition suitable for use in an automatic transmission for automobiles.

[0002]

2. Description of the Related Art Conventionally, it has been important for automatic transmission fluids for automobiles to have excellent performances such as thermal oxidation stability, wear resistance, and frictional characteristics such as wet multi-plate clutches.
There are oils such as the IE standard and the Ford MERCON standard. These automatic transmission oils include various additives (antioxidants, detergent dispersants, antiwear agents, rust preventives, metal deactivators, friction coefficient modifiers, defoamers, colorants, seal swelling agents) to base oils. Agent, viscosity index improver, etc.) are blended.

[0003]

In the recent automatic transmissions, in order to increase the transmission torque capacity in response to the weight reduction of the automatic transmission and the higher output of the engine, the friction coefficient of the wet multi-disc clutch is changed. There is a demand for increase. In addition, since the heat load increases with the reduction in weight and size, improvement in thermal oxidation stability is required.

Metallic detergent dispersants such as sulfonate and phenate are sometimes used as a friction coefficient adjusting agent in order to increase the dynamic friction coefficient of a wet multi-plate clutch, but when these are added, the total acid number (JIS K 250
1) tends to increase considerably. This is because the sulfonate or phenate contains a sulfur atom in the constituent molecule and is decomposed in the process of being used as an automatic transmission oil to generate an acidic component such as H ₂ SO ₄ .

An object of the present invention is to provide an automatic transmission oil having a friction adjusting function equivalent to that of an automatic transmission oil to which sulfonate or phenate is added and having excellent thermal oxidation stability.

[0006]

In order to solve the above-mentioned problems, the present inventors have used calcium sulphonate, which is a metal-based detergent dispersant, as a friction coefficient modifier, which has been conventionally used. Has the same friction-adjusting function as calcium phenate, magnesium sulfonate, magnesium phenate, etc., and at the same time does not generate acidic components such as H ₂ SO ₄ because it does not contain a sulfur atom in the molecule. As a result of various experiments and studies focusing attention, the present invention has been completed. The present invention is
An automatic transmission oil composition, characterized in that a lubricating base oil comprising a mineral oil, a synthetic oil or a mixed oil thereof contains at least one kind of calcium salicylate represented by the following formula (1) or (2). ..

[0007]

[Chemical 2]

The amount of calcium salicylate contained in the automatic transmission oil composition of the present invention is 0.01 to 5.0% by weight, preferably 0.1 to 2.0% by weight.
If the amount added is less than 0.01% by weight, the friction adjusting function is insufficient. On the other hand, if it exceeds 5.0% by weight, a calcium salt generated when calcium salicylate is decomposed during use as an automatic transmission oil may be deposited in the voids of the wet clutch friction material to change the friction coefficient, which is not preferable. ..

In the equations (1) and (2), R is C
_Although it is ₈ or more, C ₈ or more and C ₂₈ or less are preferable. C ₂₉ or higher is a solid but can be used by dissolving it, and is therefore included in the present invention.

As the base oil, mineral oil or synthetic oil is used which has been refined by solvent refining or hydrorefining and the wax content has been removed from these base oils to improve the low temperature fluidity. Synthetic oils include poly-α-olefin oligomers, polybutenes, diesters, polyol esters, but considering the solubility of additives, etc.,
It is preferable to use a mixture of mineral oils or a mixture of synthetic oils, rather than use alone. The viscosity of the base oil is
Considering proper viscosity for torque converters, oil pumps, gears, etc., and fluidity at low temperatures, the viscosity at 100 ° C is 2.5 to 10.
0 centistokes is preferred, more preferably 2.5
~ 5.0 centistokes. If necessary, various viscosity index improvers having a thickening effect are used. The viscosity of the composition is preferably 5 to 9 centistokes at 100 ° C, more preferably 6.5 to 8.0 centistokes, and the viscosity at -40 ° C is preferably 50,000 centipoises or less, more preferably 20, It is 000 centipoise or less.

The automatic transmission oil composition of the present invention contains an antioxidant, an antiwear agent, a dispersant, a metal deactivator, a friction coefficient adjusting agent, in order to maintain the basic performance of the automatic transmission oil. An antifoaming agent, a viscosity index improver, etc. can be used. The addition amount of these may be determined in consideration of the addition amount of the conventional automatic transmission oil composition.

As the antioxidant, 2,6-di-t-butyl-P-cresol, 2,6-di-t-butylphenol, 2,6'-di-t-butyl-α-dimethylamino-P- Cresol, phenolic compounds such as 6-di-t-butyl-o-cresol, diphenylamine, 4,4
′ -Tetramethyl-diaminodiphenyl-methane, phenyl-α-naphthylamine, alkylphenyl-β-
Amine-based compounds such as naphthylamine and phenazine, sulfur-based compounds such as sulfurized olefins, sulfurized terpenes, dialkyl sulfides and dialkyl disulfides, Zn
There are dithiophosphate compounds such as -dialkyldithiophosphate, Zn-dialkylallyldithiophosphate, and Zn-dialkyldithiocarbamate.

The antiwear agents include tricresyl phosphate, methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, 2-ethylhexyl acid phosphate, isodecyl acid phosphate, lauryl acid phosphate. Acid phosphates such as fate, tridecyl acid phosphate, stearyl acid phosphate, isostearyl acid phosphate, oleyl acid phosphate, di-2-ethylhexyl phosphate, triphenyl phosphate, tri (P-cresyl) Phosphate, tris (nonylphenyl) phosphate, triisooctyl phosphate, diphenyl isodecyl phosphate, phenyl diisodecyl phosphate, Phosphorous esters such as isodecyl phosphate, tristearyl phosphate, trioleyl phosphate, trilauryl trithiophosphate, di-2-ethylhexyl hydrogen phosphate, dilauryl hydrogen phosphate, dioleyl hydrogen phosphate , Trialkylthiophosphates, di (2-ethylhexyl) dithiophosphoric acid, di-2-ethylhexyl hydroxymethylphosphonate, triethyl-3-phosphonopropionate and other amine salt compounds of phosphoric acid esters.

Examples of the dispersant include succinimide and benzylamine. Examples of the metal deactivator include benzotriazole and thiadiazole. As the friction coefficient modifier, higher fatty acids such as oleic acid, stearic acid and palmitic acid, higher alcohols such as lauryl alcohol, oleyl alcohol and cetyl alcohol, esters such as ethyl oleate, sorbitan monostearate and oleic acid monoglyceride. And compounds of amines such as cetylamine and octadecylamine.

Examples of the defoaming agent include silicone compounds such as dimethyl polysiloxane, phenylmethyl siloxane and cyclic organosiloxane, and ester compounds such as sorbitan monolaurate and alkenyl succinic acid derivatives. Examples of the viscosity index improver include PMA (polymethacrylate), PIB (polyisobutylene), EPC (ethylene / propylene copolymer), SDC (styrene / diester copolymer) and the like.

[0016]

EXAMPLES Examples and comparative examples of the present invention will be described below. The present invention is not limited to the following examples.

The compositions of Examples and Comparative Examples are shown in Tables 1 (1) and (2).

[0018]

[Table 1]

[0019]

[Table 2]

The friction characteristics of the examples and the comparative examples are SAE No. 2 Friction tester and thermal oxidation stability for internal combustion engine lubricating oil oxidation stability test (JISK25
It evaluated by 14). The respective test conditions are shown in Tables 2 and 3. The results are shown in Table 4. In addition, Table 4 (1),
In (2), μd is a dynamic friction coefficient, μs is a static friction coefficient, and μo / μd is a static-dynamic ratio.

[0021]

[Table 3]

[0022]

[Table 4]

From Table 4, μd (dynamic friction coefficient) is 100
In any of 0 cycles and 5000 cycles, Examples 1 to 4 are comparable to Comparative Examples 1 to 3. Further, the total acid value showing thermooxidative stability is lower than that of Comparative Examples 1 to 3 in all Examples, and it is understood that the Examples have superior thermooxidative stability to Comparative Examples 1 to 3.

In this example, as described above, the experiment was conducted using the mixture of the above formulas (1) and (2), but the calcium salicylate of the above formula (1) in which R was C _{20 to} C ₂₄ was used alone. And when R in the formula (2) is C _{20 to} C _24.
When calcium salicylate of 1 was used alone, the result was the same as that of this example.

[0025]

EFFECTS OF THE INVENTION The automatic transmission oil composition of the present invention contains calcium salicylate so that it can maintain a high friction coefficient and, at the same time, has excellent thermal oxidation stability. Therefore, by using the automatic transmission oil composition of the present invention, it has become possible to reduce the weight and size of the automatic transmission for automobiles, which has been difficult in the past.

Continuation of front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technology display location C10N 30:06 30:08 30:10 40:04 (72) Inventor Tatsuo Yoshioka 1 Toyota-cho, Toyota-shi, Aichi Inside Toyota Motor Corporation

Claims (1)

[Claims] 1. A lubricating base oil comprising a mineral oil, a synthetic oil or a mixed oil thereof, and at least one of calcium salicylates represented by the following formula (1) or (2) in an amount of 0.01 to
An automatic transmission oil composition comprising 5.0% by weight. [Chemical 1]