JP2002327189A - Fluid for traction drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the deterioration of a traction coefficient and simultaneously improve fluidity at low temperature. SOLUTION: This liquid for traction drive is obtained by adding a sulfur- based heterocyclic compound containing a structure of formula 1 in at least one part of the chemical formula or a pentadecane-based compound of general formula 2 (R1 , R2 and R3 are each a 1 to 20C hydrocarbon) to a base oil containing an aliphatic compound having two cyclohexane rings in the molecule as a main component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traction drive fluid, and more particularly, to a traction drive fluid having high low-temperature fluidity and a high traction coefficient. The fluid for traction drive of the present invention is:
For example, it can be suitably used for a traction drive device of a continuously variable transmission (CVT) of a vehicle.

[0002]

2. Description of the Related Art A traction drive fluid is a fluid used for a power transmission mechanism by a traction drive. The fluid is interposed between rolling contact surfaces to transmit power and prevent direct contact between rolling elements. It plays a role as an oil. This traction drive fluid is generally classified into a liquid lubricating oil and a semi-solid or solid grease, and there are mineral oils and synthetic oils depending on the base oil as the main component. Used for applications.

Since the traction drive is a rolling transmission, its mechanism is simpler than that of a gear transmission, and a low-noise and smooth stepless transmission can be performed. For this reason, the development of a continuously variable transmission (CVT) using a traction drive is expected.

An important performance in the traction drive is a power transmission capability, 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.

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. In particular, in recent years, research on high performance or miniaturization and lightening has been advanced mainly for automotive applications, and traction drive fluids also exhibit high traction coefficient with practical properties 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 Japanese Patent Application No. 59660 and Japanese Patent Application Laid-Open No. 10-25489.

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 transmission having a traction drive mechanism, in which a base oil obtained by mixing a naphthenic hydrocarbon and polyisobutene is blended with a phosphetane derivative.

Japanese Patent Publication No. 6-31373 proposes a traction drive fluid in which polybutene is mixed with cyclohexanolcyclohexanecarboxylic acid ester or a derivative thereof.

[0011] In Japanese Patent Publication No. 7-47752,
A cyclopentadiene-based tri- to hexamer-containing cyclopentadiene-based condensed hydrocarbon 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 And a branched poly-α
-A traction drive fluid composition mixed with an olefin has been proposed.

Japanese Patent Application Laid-Open No. 7-242891 discloses that the ratio of the hydrogen amount on a norbornene ring double bond to that on a cyclopentene ring double bond (N
(D / CD) of 0.9 to 1.3, and a dimer hydride of α-alkylstyrene having 1 to 3 carbon atoms in the alkyl group. Mixed traction drive fluid compositions have been proposed.

Further, JP-A-9-59660 and JP-A-10-25489 disclose a dicyclohexyl compound mixed with a thermal copolymer of cyclopentadiene and vinyl aromatic hydrocarbon or a hydride thereof. Traction drive fluids have been proposed.

Further, traction drive fluids using silicone-based compounds have been discussed in Japanese Patent Publication No. 2-11639 and JP-A-6-271588. In the gazette, 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, 2,4
-Dicyclohexyl-2-methylpentane exemplified dimer hydride of α-alkylstyrene has a high traction coefficient, but has poor fluidity at low temperatures,
It has become difficult to put it into practical use as a continuously variable transmission oil for automobiles. Therefore, development of a practical traction drive fluid having excellent low-temperature fluidity is strongly desired.

In general, the traction coefficient of ether oil is not so high, it has never been used as a traction fluid, and a patent using ether oil as a traction fluid, or ether is mixed with traction fluid. No patents are found.

[0017]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a traction drive fluid which is excellent in low-temperature fluidity, has a high traction coefficient, and is practically excellent. .

[0018]

According to a first aspect of the present invention, there is provided a traction drive fluid comprising:
A base oil mainly composed of an alicyclic compound having two cyclohexane rings, and a sulfur-based heterocyclic compound containing a structure represented by the following formula (1) in at least a part of the chemical formula thereof: It is.

[0019]

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According to a second aspect of the present invention, there is provided a traction drive fluid represented by the following general formula (2) and a base oil mainly composed of an alicyclic compound having two cyclohexane rings in a molecule. And a pentadecane compound.

[0021]

Embedded image

(Wherein R1, R2 and R3 are C1 to C20
Hydrocarbon group)

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The traction drive fluid according to claim 1 or 2 contains a base oil mainly composed of an alicyclic compound having two cyclohexane rings in a molecule. As an alicyclic compound having two cyclohexane rings in the molecule, for example, 2,4-dicyclohexyl-2,
4-dimethylpentane can be mentioned.

The fluid for traction drive according to the first aspect contains a sulfur-based heterocyclic compound containing the structure represented by the following formula (1) in at least a part of the chemical formula thereof.

[0025]

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By adding the above-mentioned predetermined sulfur-based heterocyclic compound to a base oil containing the above-mentioned predetermined alicyclic compound as a main component, it is possible to significantly lower the low-temperature viscosity while suppressing a decrease in traction coefficient. it can.

Examples of the sulfur-based heterocyclic compound containing the structure represented by the above formula (1) in at least a part of the chemical formula include pentamethylene sulfide having only the structure represented by the above formula (1) and the following general formula ( Sulfur-based heterocyclic compounds represented by 3), (4) or (5) can be used.

[0028]

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Wherein R1 is a member selected from the group consisting of a methyl group, an ethyl group, a propyl group and a butyl group, p is an integer of 0 to 6, and R2 is a methyl group, an ethyl group, a propyl group and a butyl group. R is a kind selected from the group consisting of groups, and q is an integer of 0 to 6.) In the general formula (3), R1 and R2 may be the same or different. In addition, R1 (or R
When a plurality of (2) is provided (p (or q) = 2 to 6), one or more structural isomers may be contained therein.

[0030]

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Wherein R is a member selected from the group consisting of a methyl group, an ethyl group, a propyl group and a butyl group;
And X is an alkylene group having 1 to 4 carbon atoms, and n is an integer of 0 to 2. In the above general formula (4), when a plurality of Rs are provided (when p = 2 to 6), one or more structural isomers may be contained therein.

[0032]

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(Wherein, R1 is a member selected from the group consisting of a methyl group, an ethyl group, a propyl group and a butyl group, p is an integer of 0 to 6, and R2 is a methyl group, an ethyl group, a propyl group and a butyl group. Q is an integer of 0 to 6, X is an alkylene group having 1 to 4 carbon atoms, and n is an integer of 0 to 2. In the general formula (5) ), R1 and R2 may be the same or different. In addition, R1 (or R
When a plurality of (2) is provided (p (or q) = 2 to 6), one or more structural isomers may be contained therein.

Here, as for the addition amount of the above-mentioned predetermined sulfur-based heterocyclic compound to the base oil containing the above-mentioned predetermined alicyclic compound as a main component, the traction coefficient and the low-temperature viscosity both decrease as the addition amount increases. There is a tendency. For this reason, the addition amount of the above-mentioned predetermined sulfur-based heterocyclic compound can be appropriately set so that the obtained traction drive fluid achieves the desired traction coefficient and low-temperature viscosity. The preferable addition amount of the predetermined sulfur-based heterocyclic compound to the predetermined base oil varies depending on the type of the base oil and the sulfur-based heterocyclic compound, but is 4 to 30 v.
ol%.

Further, as for the above-mentioned predetermined sulfur heterocyclic compound, it is considered that as the molecular weight increases, it is disadvantageous to lower the low-temperature viscosity of the traction drive fluid. . From such a viewpoint, in the above general formulas (3) to (5), it is preferable to use R, R1 or R2 having as small a carbon number as possible, and it is preferable that the values of p, q or n are as small as possible.

The traction drive fluid according to the second aspect contains a pentadecane compound represented by the following general formula (2).

[0037]

Embedded image

(Wherein R1, R2 and R3 are C1 to C20
By adding the above-mentioned predetermined pentadecane-based compound to the base oil containing the above-mentioned predetermined alicyclic compound as a main component, it is possible to significantly lower the low-temperature viscosity while suppressing a decrease in the traction coefficient. it can.

Here, as for the addition amount of the above-mentioned predetermined pentadecane-based compound to the base oil composed of the above-mentioned predetermined alicyclic compound, both the traction coefficient and the low-temperature viscosity tend to decrease as the addition amount increases. For this reason, the addition amount of the above-mentioned predetermined pentadecane-based compound can be appropriately set so that the obtained traction drive fluid achieves the desired traction coefficient and low-temperature viscosity. The preferable addition amount of the predetermined pentadecane compound to the predetermined base oil varies depending on the type of the base oil and the pentadecane compound, but can be about 4 to 30 vol%.

Further, as for the above-mentioned predetermined pentadecane compound, it is considered that as the molecular weight increases, it is disadvantageous to lower the low-temperature viscosity of the traction drive fluid. From this viewpoint, the above general formula (2)
It is preferable to use R1, R2 or R3 having as few carbon atoms as possible.

The above-mentioned specified sulfur-based heterocyclic compound or the specified pentadecane-based compound cannot be used alone as an automobile traction oil because of its low flash point. Therefore, in the fluid for traction drive of the present invention, these compounds are added to the above-mentioned predetermined base oil. As described above, the base oil composed mainly of an alicyclic compound having two cyclohexane rings in the molecule is used because the base oil composed of such alicyclic compound has a traction coefficient and a flash point. Is high.

[0042]

The present invention will be specifically described below with reference to examples and comparative examples.

Example 1 A traction drive fluid of Example 1 was composed of 85 vol% of a base oil mainly composed of an alicyclic compound having two cyclohexane rings in a molecule, and a predetermined sulfur-based heterocyclic compound. Pentamethylene sulfide 15vo represented by the following chemical formula (1)
1%.

[0044]

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As the base oil, commercially available traction oil "Santotrac 50" (main component 2,4-dicyclohexyl-2,4-dimethylpentane, manufactured by FINDETT, USA)
It was adopted.

Comparative Example 1 Commercially available traction oil "Santotrac 50" (main component 2,4-dicyclohexyl-)
Comparative Example 1 was 2,4-dimethylpentane (manufactured by FINDETT, USA).

Comparative Example 2 Commercially available traction oil "Santotrac 50" (main component 2,4-dicyclohexyl-
2,4-dimethylpentane, manufactured by USA FINDETT) 85v
ol% and 15 vol% of mineral oil “ATF (Automatic Transmission Fluid)” were used as Comparative Example 2.

(Evaluation) Then, in order to measure the traction coefficient and the low-temperature viscosity of the traction drive fluids of Example 1 and Comparative Examples 1 and 2, a rolling-friction and wear tester (4-cylinder tester manufactured by Shinko Zoki Co., Ltd.) ), And using a roller having a roller radius of 40 mm and a surface roughness of 0.03 μm, the traction coefficient and the low-temperature viscosity at −40 ° C. were measured under the conditions shown in Table 1. The result is shown in FIG. The slip ratio refers to a percentage of the average speed with respect to the relative speed of the cylinder.

[0049]

[Table 1]

As shown in FIG. 1, in the traction drive fluid of Comparative Example 2 to which ATF was added, the viscosity at -40 ° C. was significantly reduced, but the traction coefficient was also significantly reduced.

On the other hand, the traction drive fluid of Example 1 to which pentamethylene sulfide as a predetermined sulfur-based heterocyclic compound was added had a greatly reduced viscosity at -40 ° C., but had a traction coefficient of 0.1. 093, which is smaller than that of Comparative Example 2. The traction drive fluid of Example 1 has a -40 ° C. viscosity of about 3.5 × 10 ⁴ mPa · s and a traction coefficient of about 0.086. The fluid is -40
The traction coefficient was about 0.096 when the viscosity at ° C. was about 3.5 × 10 ⁴ mPa · s equivalent to that of Comparative Example 2.

Accordingly, pentamethylene sulfide as a predetermined sulfur-based heterocyclic compound is added to 2,4-dicyclohexyl-2,4-dimethylpentane as an alicyclic compound having two cyclohexane rings in the molecule. The traction drive fluid of Example 1 described above can lower the low-temperature viscosity at -40 ° C. while suppressing a decrease in the traction coefficient as compared with the traction drive fluid of Comparative Example 2 to which engine oil is added. Was.

Further, from FIG. 1, the viscosity at -40 ° C. of the traction drive fluid of Example 1 to which 15 vol% of pentamethylene sulfide was added was 1.6 × 10 ⁴ mPa.
S of the traction drive fluid of Comparative Example 1 in which pentamethylene sulfide was not added.
Since the viscosity at 40 ° C. is about 2.3 × 10 ⁵ mPa · s, if pentamethylene sulfide is added at about 4 vol% or more, the viscosity at −40 ° C. will be about 1 × 10 ⁵ mPa · s or less, which is unapproved for automobiles. It can be seen that the minimum required level of the traction drive fluid used in the transmission is satisfied.

Example 2 A traction drive fluid of Example 2 was composed of 85 vol% of a base oil mainly composed of an alicyclic compound having two cyclohexane rings in a molecule, and a predetermined pentadecane compound. And 1,15,9-trimethyl-1,5,9 triazacyclododecane represented by the following chemical formula (6): 15 vol%.

[0055]

Embedded image

As the base oil, commercially available traction oil "Santotrac 50" (main component 2,4-dicyclohexyl-2,4-dimethylpentane, manufactured by FINDETT, USA)
It was adopted.

(Evaluation) The traction coefficient and the low temperature viscosity at -40 ° C. were measured in the same manner as in Example 1. The results are shown in FIG. 2 together with the results of Comparative Examples 1 and 2.

As shown in FIG. 2, the traction drive fluid of Example 2 to which 1,5,9-trimethyl-1,5,9-triazacyclododecane was added as a predetermined pentadecane-based compound had a traction coefficient of Is 0.083
And the viscosity at −40 ° C. is 5000 mPa ·
s.

Further, the traction drive fluid of Example 2 had a viscosity of -40 ° C. of 3.5 × 10 3 which was equivalent to that of Comparative Example 2.
The traction coefficient when indicating about ⁴ mPa · s is 0.
It was about 093.

Therefore, 2,4-dicyclohexyl-2,4-dimethylpentane, which is an alicyclic compound having two cyclohexane rings in the molecule, is compared with 1,5,9-trimethyl as a predetermined pentadecane compound. −
The traction drive fluid of Example 2 to which 1,5,9 triazacyclododecane was added, as compared with the traction drive fluid of Comparative Example 2 to which engine oil was added, while suppressing a decrease in traction coefficient, The low temperature viscosity at 40 ° C. could be reduced.

As shown in FIG. 2, when 1,3,9-trimethyl-1,5,9-triazacyclododecane is added in an amount of about 3 vol% or more, the viscosity at -40 ° C. becomes 1 × 10 ⁵ mPa · s.
It can be seen that the minimum required level of the traction drive fluid used in the continuously variable transmission for automobiles is satisfied.

[0062]

As described above in detail, according to the traction drive fluid of the present invention, the low-temperature viscosity can be greatly reduced while suppressing the decrease in the traction coefficient. Therefore, the traction drive fluid of the present invention has improved both traction characteristics and low-temperature fluidity to the level of practical use as a continuously variable transmission for automobiles.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the traction coefficient and the viscosity at −40 ° C. for the traction drive fluids of Example 1 and Comparative Examples 1 and 2.

FIG. 2 is a graph showing the relationship between the traction coefficient and the viscosity at −40 ° C. for the traction drive fluids of Example 2 and Comparative Examples 1 and 2.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C10M 133/38 C10M 133/38 135/34 135/34 // C10N 30:00 C10N 30:00 Z 30:02 30: 02 30:08 30:08 40:04 40:04 F term (reference) 4H104 BA02A BE26A BE26C BG17A BG17C LA01 LA04 LA20 PA03

Claims (2)

[Claims] 1. A base oil mainly composed of an alicyclic compound having two cyclohexane rings in a molecule, and a sulfur-based heterocyclic compound containing a structure represented by the following formula (1) in at least a part of a chemical formula: A fluid for traction drive, comprising: Embedded image 2. A base oil mainly composed of an alicyclic compound having two cyclohexane rings in a molecule, and a base oil represented by the following general formula (2):
A traction drive fluid excellent in low-temperature fluidity, comprising a pentadecane compound represented by the formula: Embedded image (Wherein R1, R2 and R3 are C1 to C20 hydrocarbon groups)