JP2003129076A - Fluid composition for traction drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a traction drive fluid excellent in low temperature flowability, having high traction coefficient and excellent in practicality. SOLUTION: A fluid composition for traction drive is provided that is characterized in containing a compound having a six-membered saturated ring including at least one oxygen represented by formula (1) or (2) (wherein X denotes oxygen atom or methylene (CH2 ) group; R<1> denotes a 1-6C alkylene group; and R<2> denotes a saturated cyclic hydrocarbon group).

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traction drive fluid composition containing a compound having a 6-membered saturated ring containing at least one oxygen.
The present invention relates to a traction drive fluid composition containing a compound having a 6-membered saturated ring containing at least one oxygen, which is useful as a traction drive fluid having a high traction coefficient and excellent low-temperature fluidity. [0002] A traction drive fluid is a fluid used for a power transmission mechanism by a traction drive. The traction drive fluid is used in a traction drive device such as a continuously variable transmission (CVT) of a vehicle.
It intervenes on the rolling contact surface, transmits power, and plays a role as a lubricating oil that prevents direct contact between the rolling elements. Since the traction drive is a rolling transmission, the mechanism is simpler than that of a gear transmission, and low noise and a smooth continuously variable transmission can be performed. Therefore, development of an automobile traction drive is expected. An important performance in a traction drive is dynamic power transmission, and a traction coefficient μ (μ = T / P) defined by a ratio of a tangential force (traction force) T to a normal load (normal force) P. ), The larger the traction coefficient, the larger the transmission capacity. Traction drive fluids are generally broadly classified into liquid lubricating oils and semi-solid or solid greases, but there are mineral oils and synthetic oils depending on the base oil used as the main component. Have been. As described above, in a traction drive device such as a continuously variable transmission, a traction drive fluid having a high traction coefficient is desired from the viewpoint of power transmission capability. Especially in recent years, research on high performance or small size and light weight has been advanced especially for automotive applications, and traction drive fluids also exhibit high traction coefficient with practicality such as excellent viscosity temperature characteristics and low temperature fluidity. Is required. Conventionally, a traction drive fluid has been disclosed in Japanese Patent Publication No. 53-36105,
No. 11639, Japanese Patent Publication No. 5-87117, Japanese Patent Publication No. 5-88918, Japanese Patent Publication No. 6-31373, Japanese Patent Publication No. 7-47752, Japanese Unexamined Patent Publication No. Hei 6-2715.
No. 88, JP-A-7-242891, JP-A-9
Various compounds have been proposed in numerous patents and literatures, such as JP-A-59660 and JP-A-10-25489. [0005] For example, Japanese Patent Publication No. 53-36105 proposes a power transmission method using a compound exemplified by 2,4-dicyclohexyl-2-methylpentane as a power transmission fluid. Japanese Patent Publication No. 5-87117 proposes a traction drive fluid composition in which polycyclohexylalkane is mixed with squalane or polyolefin oil. Japanese Patent Publication No. 5-88918 proposes a lubricant for a power transmission device having a traction drive mechanism, in which a phosphetane derivative is blended in a base oil in which a naphthenic hydrocarbon and polyisobutene are mixed. Japanese Patent Publication No. 6-31373 discloses a traction drive fluid in which polybutene is mixed with cyclohexanol cyclohexanecarboxylic acid ester or a derivative thereof. Japanese Patent Publication No. 7-47552 discloses that the ratio (ND / CD) of the hydrogen amount on the norbornene ring double bond to the cyclopentene ring double bond in a cyclopentadiene-based trimer to hexamer is 0.9. A fluid composition for traction drive has been proposed in which a hydride of a cyclopentadiene-based condensed hydrocarbon having a molecular weight of 1.3 to 1.3 and a branched poly-α-olefin are mixed. JP-A-7-2428
No. 91 discloses a cyclopentadiene trimer to hexamer having a hydrogen content ratio (ND / CD) of 0.9 to 1.3 on a norbornene ring double bond and a cyclopentene ring double bond. A fluid composition for traction drive has been proposed in which a hydride of a cyclopentadiene-based condensed ring hydrocarbon and a dimer hydride of an α-alkylstyrene having 1 to 3 carbon atoms in an alkyl group are mixed. Further, JP-A-9-59660 and JP-A-10-25489 disclose a traction drive in which a dicyclohexyl compound and a thermal copolymer of cyclopentadiene and vinyl aromatic hydrocarbon or a hydride thereof are mixed. Working fluids have been proposed. Further, traction drive fluids using silicone-based compounds are also slightly examined, for example, in Japanese Patent Publication No. 2-11639 and Japanese Patent Application Laid-Open No. 6-271588.
In Japanese Patent Application Laid-Open Publication No. H11-264, a traction drive fluid using cyclohexylmethyl silicone is proposed. However, in spite of these proposals, in addition to a high traction coefficient, there are few practical traction drive fluids. In particular, 2,
The dimer hydride of α-alkylstyrene exemplified by 4-dicyclohexyl-2-methylpentane has a high traction coefficient, but has poor fluidity at low temperatures, and is difficult to be practically used as a continuously variable transmission oil for automobiles. It has become. Therefore, development of a practical traction drive fluid having excellent low-temperature fluidity has been strongly desired. In addition, there is no patent to use a compound having a saturated ring containing oxygen as a traction fluid or to mix it with a traction fluid. SUMMARY OF THE INVENTION An object of the present invention is to provide a traction drive fluid composition which is excellent in low-temperature fluidity, has a high traction coefficient, and is practically excellent. The present inventors have made intensive studies to overcome the above-mentioned problems of the prior art, and as a result, newly synthesized compounds having a specific structure, ie, at least one compound having a specific structure.
Since a compound having a six-membered saturated ring containing two oxygens, for example, tetrahydropyran or dioxane, has a high traction coefficient and excellent low-temperature fluidity, it is practically used as a part or all of a base oil of a traction drive fluid. It has been found that an excellent traction drive fluid can be obtained. The present invention has been completed based on these findings. That is, according to the present invention, a traction drive characterized by containing a compound having a 6-membered saturated ring containing at least one oxygen represented by the following general formula (1) or (2): A fluid composition is provided. [0010] Wherein X is an oxygen atom or methylene (C
H ₂ ), R ¹ represents an alkylene group having 1 to 6 carbon atoms, and R ² represents a saturated cyclic hydrocarbon group. Further, as described above, the present invention relates to a traction drive fluid composition containing a compound having a 6-membered saturated ring containing at least one oxygen, and is preferable. The following are also included as embodiments. (1) In the general formula (1) or (2), R ² is a cyclohexyl ring, wherein the traction drive fluid composition is used. (2) The traction drive fluid composition according to any of the above, wherein in the general formula (1) or (2), X is an oxygen atom. (3) The traction drive fluid composition according to any of the above, wherein in the general formula (1) or (2), R ¹ is an ethylene group. (4) a base oil composed of 2,4-dicyclohexyl-2-methylpentane, a base oil composed of hydrogenated cyclopentadiene oligomer having an average molecular weight of 190 to 250, or a mixed base oil of any of the above, At least one of the statements
A traction drive fluid composition comprising a compound having a six-membered saturated ring containing two oxygens. (5) The traction drive fluid composition according to (4), further comprising a base oil composed of polybutene having an average molecular weight of 300 to 3500. (6) antiwear agents, extreme pressure agents, friction modifiers, antioxidants,
The fluid for traction drive according to any of the above, further comprising at least one additive selected from the group consisting of a viscosity index improver, a detergent / dispersant, a metal deactivator, and an antifoaming agent. Composition. (7) The traction drive fluid composition according to any of the above, wherein the traction coefficient is 0.070 or more and the low-temperature viscosity at -40 ° C is 60 Pa · s or less. Hereinafter, the present invention will be described in detail. The fluid composition for traction drive of the present invention,
It has features such as a high traction coefficient, a low viscosity at −40 ° C., and excellent low-temperature fluidity. The traction drive fluid composition of the present invention usually has a high traction coefficient of 0.070 or more. Further, the fluid composition for traction drive of the present invention has a low-temperature viscosity at −40 ° C. of 60 Pa · s or less, and can be used at a low temperature. That is, when the device is operated in a cold region or in winter, the temperature may be 0 ° C. or less outdoors, or around −40 ° C. in some cases. Therefore, since the fluid composition for traction drive of the present invention has excellent low-temperature fluidity, the traction drive device can be operated even under a low-temperature condition of around −40 ° C. Further, the traction drive fluid composition of the present invention utilizes the above-mentioned features to transmit power and to directly contact rolling elements in a traction drive device such as a continuously variable transmission for automobiles. It can be suitably used as a lubricant that plays a role as a lubricating oil for preventing oil. Moreover, since the traction drive fluid composition of the present invention has a high traction coefficient, as described above, the pressing load of the rolling elements can be reduced, and the fatigue life of the traction drive device body can be significantly extended. Therefore, the reliability of the device can be improved, which can contribute to downsizing of the device. 1. Base oil (1) Compound having a 6-membered saturated ring containing at least one oxygen In the traction drive fluid composition of the present invention, it is most effective to contain a compound having a 6-membered saturated ring containing at least one oxygen. There are features. At least one
Specific examples of the compound having a six-membered saturated ring containing two oxygens include a compound having a specific structure represented by the following general formula (1) or (2). Embedded image In the above formula, X represents an oxygen atom or a methylene (CH ₂ ) group, and is preferably an oxygen atom. When X is an oxygen atom, the 6-membered saturated ring contains two oxygens,
It becomes a 1,3-dioxane or 1,4-dioxane skeleton. When X is a methylene (CH ₂ ) group, the 6-membered saturated ring becomes a 6-membered saturated ring containing one oxygen, that is, a tetrahydropyran skeleton. R ¹ represents an alkylene group having 1 to 6 carbon atoms, and is preferably an ethylene group. Further, R ² represents a saturated cyclic hydrocarbon group, and has 1 to 1 carbon atoms.
The saturated cyclic hydrocarbon group which may have a substituent of the alkyl group 4 is a hydrocarbon group having a cyclohexyl ring. Further description will be made in detail. The first structural feature of the compound represented by the general formula (1) or (2) is that the compound has a 6-membered saturated ring containing at least one oxygen. The present inventors have determined that the 6 containing at least one oxygen
By the function of the member saturated ring, it has a high traction coefficient,
It is speculated that the low-temperature fluidity is improved. next,
A second structural feature is that the above-mentioned 6-membered saturated ring and R ² via R ¹ are a saturated cyclic hydrocarbon group which may have a substituent of an alkyl group having 1 to 4 carbon atoms, for example, , A hydrocarbon group having a cyclohexyl ring or a bridged cyclic hydrocarbon group. Thus, the general formula (1) or (2)
Can have a higher traction coefficient. Of the saturated cyclic hydrocarbon groups, those having a cyclohexyl ring or the like, that is, as the cycloalkane, include C _{6 to} C ₁₂ monocyclic or bicyclic ones. For cyclic ones, C
Include ₆ cyclohexyl ring cyclooctyl ring (cyclohexyl group) or a C _8, cyclohexyl ring (cyclohexyl group) of C ₆ are preferable. In addition, these cyclohexyl rings and the like may further have one or two substituents such as an alkyl group having 1 to 4 carbon atoms. Also, by way of bicyclic, for example, decalin ring to C ₁₀ and the like, also, like in the decalin ring, optionally having one to three substituents such as an alkyl group having 1 to 4 carbon atoms Good. Also,
Examples of the bridged cyclic hydrocarbon group include bicyclo [2.2.
1] Heptyl group (bicycloheptane ring) and the like, and the bridged ring may have 1 to 3 substituents such as an alkyl group having 1 to 4 carbon atoms. Further, R ¹ of the compound represented by formula (1) or (2) represents an alkylene group having 1 to 6 carbon atoms, preferably an alkylene group having 1 to 4 carbon atoms, more preferably methylene. Group, ethylene group, dimethylmethylene group,
Or it is a propylene group. The compound represented by the general formula (1) or (2) used as the base oil of the fluid composition for traction drive of the present invention is not particularly limited with respect to raw materials and production methods, and can be obtained by various methods. Although it can be produced, usually, it can be produced by the following method. As a raw material, as a compound corresponding to a 6-membered saturated ring containing at least one oxygen of the general formula (1) or (2), for example, 2-
Using (2-bromoethyl) -1,3-dioxane, this was mixed with a solvent such as copper iodide (CuI) and tetrahydrofuran, and the flask containing the mixture was placed at −6.
The mixture is cooled to 0 ° C., and reacted by dropwise addition of cyclohexylmagnesium chloride under a nitrogen atmosphere. After adding ice water to the reaction mixture, the organic phase is extracted with a solvent such as ethyl acetate, washed and dried, and then the solvent is distilled off, vacuum distillation is performed. A compound of the following structural formula (3), which is a typical example of the compound represented by 1) or (2), that is, 2- (2-cyclohexylethyl) -1,3-dioxane can be obtained. Embedded image Compounds represented by the general formula (1) or (2) other than the compound of the above structural formula (3) can be obtained by the same method as described above. And the like. Embedded image The compound represented by the general formula (1) or (2) thus produced is excellent in low-temperature fluidity, has a high traction coefficient, and is well-known for traction drive fluids and commonly used mineral oils. Also, since it has excellent compatibility with synthetic oils and additives for lubricating oils, it is useful as a base oil for traction drive fluid compositions. (2) Mixed base oil In the present invention, the compound having a 6-membered saturated ring containing at least one oxygen, for example, the compound represented by the general formula (1) or (2), is itself a traction drive. It can be used as a base oil of a traction fluid, but if there is a lack of traction coefficient or viscosity coefficient, a known traction drive fluid base with a higher traction coefficient or superior low-temperature fluidity can be used. It is used even when mixed with oil. In the present invention, as a base oil of a traction drive fluid used as a mixture with a compound having a 6-membered saturated ring containing at least one oxygen, for example, a compound represented by the general formula (1) or (2) Is, for example, 2,4-
Dicyclohexyl-2-methylpentane.
This 2,4-dicyclohexyl-2-methylpentane is a compound represented by the following structural formula (4), which is known as a traction drive fluid, and has an excellent traction coefficient, but is near -40 ° C. Has a disadvantage that the viscosity at low temperature is high and the low-temperature fluidity is inferior. It is said that the traction coefficient of the mixed oil generally has additivity, and an approximate mixing ratio can be determined from the traction coefficient of each base oil. Embedded image In one embodiment of the present invention, the base oil of the traction drive fluid composition to be mixed with the compound represented by the general formula (1) or (2) is
4-Dicyclohexyl-2-methylpentane, a hydrogenated cyclopentadiene oligomer having an average molecular weight of 190 to 250, or a polybutene having an average molecular weight of 300 to 3500 is used. Depending on the required performance of the traction drive fluid according to the application, it can be used singly or in various combinations, and the viscosity can be adjusted by mixing a small amount of a high-viscosity polymer compound such as polybutene. In these base oils,
Alternatively, by blending a compound represented by the general formula (1) or (2) as a mixed base material with a combination of these base oils, consideration is given to other practical performances such as viscosity and oil seal rubber compatibility. While maintaining a high traction coefficient, the low-temperature fluidity can be improved. The compounding ratio of the traction drive fluid composition of the present invention, that is, the compound having at least one oxygen-containing 6-membered saturated ring represented by the general formula (1) or (2) may be various base oils. Can be changed appropriately according to the balance of performance. That is, by appropriately changing the compounding ratio of the compound represented by the general formula (1) or (2), the traction coefficient is kept high, the low-temperature viscosity is low, and the compound can be used even in a cold region or in the winter. Traction drive fluid. For example, as the base oil, the general formula (1) or (2)
When the compound represented by the general formula (1) or (2) is mixed with 2,4-dicyclohexyl-2-methylpentane, the compound represented by the formula The ratio is appropriately changed depending on the target low-temperature viscosity and traction coefficient, and is 100 to 40% by weight of the compound represented by the general formula (1) or (2).
2,4-dicyclohexyl-2-methylpentane 0-6
A range of 0% by weight is preferred. General formula (1) or (2)
If the compounding ratio of the compound represented by is less than 40% by weight,
Insufficient low-temperature fluidity. 2. Additive The traction drive fluid composition of the present invention contains the above-mentioned compound having a 6-membered saturated ring containing at least one oxygen as a base oil of the traction drive fluid. In order to ensure adapted practical performance, if necessary, power transmission oil for automobiles,
For example, various additives used in automatic transmission oils and transmission gear oils, such as antiwear agents, extreme pressure agents, friction modifiers, antioxidants, viscosity index improvers, cleaning dispersants, metal deactivators, and An antifoaming agent or the like can be appropriately added as long as the object of the present invention is not impaired. The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. The traction drive fluid compositions obtained in Examples and Comparative Examples were evaluated by the following methods. 1. Evaluation and measurement method of physical properties <Traction coefficient measurement device and measurement conditions> Four-cylinder traction tester peripheral speed: 5 m / sec Slip ratio: 2% Average Hertz pressure: 1.0 GPa Roller temperature: room temperature [0033] <Low temperature viscosity Measurement method> Low temperature viscosity, that is, Brookfield viscosity at -40 ° C is AST
It was measured with a Brookfield viscometer specified in MD2983-80. The development target of the low-temperature viscosity was that the Brookfield viscosity at −40 ° C. was 60 Pa · s or less. 2. Synthesis of Compound Having a Six-membered Saturated Ring Containing at least One Oxygen [Synthesis Example] A dried flask was placed in a nitrogen atmosphere under a nitrogen atmosphere.
42 mol (81.9 g) of 2- (2-bromoethyl)-
1,3-Dioxane, 0.042 mol (8.0 g) of copper iodide (CuI) and 300 ml of dehydrated tetrahydrofuran solvent were poured, and the mixture was stirred with a mechanical stirrer for several minutes. The flask was cooled to −60 ° C. and stirred under a nitrogen atmosphere for about 30 minutes. Next, 0.5 mol (230 ml) of a 2M solution of cyclohexylmagnesium chloride was dropped and reacted while controlling the reaction solution so as not to exceed −50 ° C. After completion of the dropwise addition, the reaction product was stirred at -50 ° C for 3 hours, and further stirred at room temperature for 3 hours to proceed the reaction. After completion of the reaction, 30 ml of ice water was added to the reaction product, and the organic phase was extracted twice with 300 ml of ethyl acetate. The collected organic phase was washed with brine, dried over magnesium sulfate, the organic solvent was removed under reduced pressure, and the mixture was concentrated. The crude product is purified by distillation (0.2 mmHg, 92-96 ° C),
As a transparent liquid, 67 g of a compound represented by the following structural formula (3), that is, 2- (2-cyclohexylethyl)
-1,3-Dioxane was obtained in a yield of about 80%. Embedded image 3. Traction drive fluid composition [Example 1] In Example 1, the oxygen-containing cyclic compound represented by the structural formula (3) obtained in Synthesis Example 1 was used as a base oil based on the total amount of the traction drive fluid composition. Only 96.
6% by weight, about 3.4% by weight in total of various additives shown in Table 1.
Were each formulated in a fixed amount to prepare a traction drive fluid composition. Table 1 shows the measurement results of the composition and physical properties of the traction drive fluid composition. Example 2 In Example 2, the oxygen-containing cyclic compound 39.3 represented by the structural formula (3) obtained in Synthesis Example 1 was used as a base oil on the basis of the total amount of the fluid composition for traction drive. 48.1% by weight of 2,4-dicyclohexyl-2-methylpentane, and an average molecular weight of 1000% by weight.
Was mixed with 9.2% by weight of polybutene to prepare a fluid composition for traction drive, and various additives shown in Table 1 were formulated in fixed amounts. Table 1 shows the measurement results of the composition and physical properties of the traction drive fluid composition. [Comparative Examples 1 to 3] In Comparative Examples 1 to 3, base oils as shown in Table 1, that is, in Comparative Example 1, only 2,4-dicyclohexyl-2-methylpentane was used. In Comparative Example 3 containing only mineral oil, a traction drive fluid containing only dicyclohexyl was used, and further, the same additives as in Examples 1 and 2 were formulated. Table 1 shows the measurement results of the composition and physical properties of the traction drive fluid composition. [Table 1] From these evaluation results, a traction drive fluid composition having excellent low-temperature fluidity, high traction coefficient, and excellent practicality was obtained by containing an oxygen-containing cyclic compound having a specific structure as a base oil. It turned out to be. According to the present invention, there is provided a traction drive fluid composition which is excellent in low-temperature fluidity, has a high traction coefficient, and is practically excellent. INDUSTRIAL APPLICABILITY The traction drive fluid composition of the present invention is used as a lubricant that functions as a lubricating oil that transmits power and prevents direct contact between rolling elements in a traction drive device such as an automobile continuously variable transmission. can do.
Further, the fluid composition for traction drive of the present invention,
Since it has a high traction coefficient and is excellent in low-temperature fluidity and practical, it can contribute to downsizing of the device and reliability at a wider environmental temperature.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Noboru Umemoto             1-3-1 Nishitsurugaoka, Oi-machi, Iruma-gun, Saitama             No. TonenGeneral Sekiyu KK             Inside (72) Inventor Shigehiko Yoshimura             1-3-1 Nishitsurugaoka, Oi-machi, Iruma-gun, Saitama             No. TonenGeneral Sekiyu KK             Inside (72) Inventor Kazushige Kubono             1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto             Inside the car company F term (reference) 4H104 BB10A LA01 LA04 LA20                       PA03

Claims (1)

Claims: 1. A traction drive comprising a compound represented by the following general formula (1) or (2) and having a 6-membered saturated ring containing at least one oxygen. Fluid composition. Embedded image (Wherein, X represents an oxygen atom or a methylene (CH ₂₎ group, ^{R 1} is an alkylene group having 1 to 6 carbon atoms, ^{R 2}
Represents a saturated cyclic hydrocarbon group. )