JPH0531913B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a traction drive fluid;
More specifically, the present invention relates to a traction drive fluid that has low viscosity and exhibits excellent traction performance over a wide temperature range from low to high temperatures.

[Problems to be solved by conventional technology and invention]

In general, traction drive fluids are fluids used in traction drive devices (friction drive devices using rolling contact), such as continuously variable transmissions for automobiles, continuously variable transmissions for industrial use, and hydraulic equipment. Additionally, safety against oxidation, economy, etc. are required.

In recent years, research has been focused on reducing the size and weight of traction drive devices, mainly for automotive applications, and along with this, the traction drive fluid used in these traction drive devices has also been developed to reduce the size and weight of traction drive devices, which can be used under various harsh conditions. Stably high performance over a wide temperature range from low to high temperatures (approximately -30 to 140℃) (high traction coefficient, low viscosity, excellent thermal and oxidation stability) They are required to be able to demonstrate their abilities (e.g.,

However, until now, Tokuko Publication No. 46-338,
Various traction drive fluids have been developed, including Japanese Patent Publication No. 46-339, but none of them can satisfy the above-mentioned required characteristics.
Various problems arose. For example, a compound that exhibits a high traction coefficient at high temperatures has a high viscosity and a large stirring loss, resulting in low transmission efficiency and also has problems in low-temperature startability. On the other hand, compounds with low viscosity and excellent transmission efficiency have a low traction coefficient at high temperatures, and their viscosity decreases too much at high temperatures, causing problems with the lubrication of traction transmission devices.

[Means for solving problems]

Therefore, the inventors of the present invention have conducted extensive research in order to solve the above-mentioned problems of the conventional technology and to develop a fluid for traction drives that has low viscosity and excellent performance over a wide temperature range from low to high temperatures. Ta.

As a result, they discovered that a traction drive fluid having the desired traction performance can be obtained by blending a hydrogenated trimeric or higher polymer of cyclic monoterpenoids with other traction oil. . The present invention was completed based on this knowledge.

That is, the present invention provides a traction drive fluid characterized by containing a hydrogenated trimer or higher polymer of cyclic monoterpenoids.

There are various types of cyclic monoterpenoids, but preferred ones include menthadienes, pinenes, and bicyclo[2.2.1]heptanes.

Here, menthadiene has a basic skeleton of 1, 2, 1, 3 or 1, 4 of the cyclohexane ring.
It has two carbon-carbon double bonds in a structure substituted with a methyl group and an isopropyl group, specifically, limonene; isolimonene; α-, β-, γ-terpinene ; α-, β-phellandrene; terpinolene; silvestrene, and the like. Furthermore, although it is possible to use these compounds substituted with an alkyl group or a hydroxyl group, it is preferable to use unsubstituted menthadienes. Also, mixtures of these can be used as well.

Pinenes include α-pinene (d-form, l-form, dl
), β-pinene (d-form, l-form), δ-pinene (d
(1-isomer, l-isomer), orthodene, and mixtures thereof may also be used. Furthermore, although it is possible to use these compounds substituted with an alkyl group or a hydroxyl group, it is preferable to use unsubstituted pinenes.

The above bicyclo[2.2.1]heptanes include camphene (d-form, l-form, dl-form), bornylene (d-form,
l-form), α-fenthiene (d-form, l-form, dl-form),
β-Fentien (d-form, DL-form), γ-Fentien, δ-Fentien, ε-Fentien, ζ
-Fuentien, borneol (d-form, l-form, dl
), π-borneol (d-form, l-form), ω-borneol, isoborneol (d-form, l-form, dl
camphuene hydrate), α-phentyl alcohol (d-form, l-form, dl-form), β-phentyl alcohol (d-form, l-dldl-form), α-isophentyl alcohol (d-form, l-form) Examples thereof include β-isophenthyl alcohol (d-isomer, l-isomer, dl-isomer), and mixtures thereof may also be used.
Furthermore, compounds obtained by introducing various substituents into these compounds can also be used.

Polymerization of the above-mentioned cyclic monoterpenoids to form a trimer or higher polymer is carried out in the presence of a catalyst and optionally using a solvent. Although various catalysts can be used for the polymerization of the cyclic monoterpenoids, acidic catalysts are generally used. Specifically, white earths such as activated clay and acid clay, mineral acids such as sulfuric acid, hydrochloric acid, and hydrofluoric acid, organic acids such as p-toluenesulfonic acid and triflic acid, aluminum chloride, ferric chloride, and chloride. Lewis acids such as stannic, boron trifluoride, boron tribromide, aluminum bromide, gallium chloride, gallium bromide, and solid acids such as zeolites,
Various materials such as silica, alumina, silica/alumina, cation exchange resins, and heteropolyacids can be used, and they may be selected appropriately taking into consideration ease of handling, economical efficiency, and the like. The amount used is not particularly limited, but is usually in the range of 0.1 to 100% by weight, preferably 0.5 to 20% by weight based on the cyclic monoterpenoids.

When polymerizing cyclic monoterpenoids into trimers or higher, a solvent is not necessarily required, but it can be used to handle the cyclic monoterpenoids and catalyst during the reaction or to control the progress of the reaction. preferable. Such solvents include n
-pentane n-hexane, heptane, octane,
Most saturated hydrocarbons such as nonane, decane, cyclopentane, cyclohexane, methylcyclohexane, decalin, etc. can be used, and if the catalyst is a catalyst with weak reaction promotion properties such as white earth, benzene, toluene, xylene etc. Aromatic hydrocarbons such as, tetralin, etc. can also be used.

The polymerization reaction is carried out in the presence of these catalysts, and the reaction conditions are generally set within a temperature range of -30°C to 180°C depending on the type of catalyst, additives, etc. For example, when the catalyst is white earth or zeolite, the reaction temperature is from room temperature to 180℃, preferably 60℃ or higher, and when other catalysts are used, the reaction temperature is -30℃ or higher.
It is carried out at a temperature of 0°C to 100°C, preferably 0°C to 60°C.
In the above polymerization, not only can homopolymerization be performed using one type of cyclic monoterpenoid as a raw material, but also copolymerization can be performed using two types of cyclic monoterpenoids as raw materials.

Next, the trimer or higher polymer (including copolymer) of cyclic monoterpenoids thus obtained is hydrogenated to obtain the desired hydrogenated polymer. Hydrogenation may be performed on the entire amount of the above-mentioned trimer or higher polymer, or may be performed by fractionating or fractionating a portion thereof.

This hydrogenation is also carried out in the presence of a catalyst, similar to the above-mentioned polymerization. It is possible to use catalysts known as so-called hydrogenation catalysts, including more than one type. The amount of this catalyst added is based on the above polymer.
It ranges from 0.1 to 100% by weight, preferably from 1 to 10% by weight.

Also, like the polymerization reaction described above, this hydrogenation proceeds even without a solvent, but a solvent can also be used.
In that case, the types of solvent include n-pentane,
Most liquid saturated hydrocarbons such as n-hexane, heptane, octane, nonane, decane, dodecane, cyclopentane, cyclohexane, methylcyclohexane, etc. can be used. Furthermore, liquids such as aromatics, olefins, alcohols, ketones, and ethers can be used, but saturated hydrocarbons are particularly preferred.

The reaction temperature is usually room temperature to 300°C, preferably
The temperature is 40 to 200℃, and the reaction pressure is from normal pressure to 200Kg/
It can be carried out at a pressure of cm ² G, preferably in the range of normal pressure to 100 kg/cm ² G, and can be carried out in the same manner as general hydrogenation.

The viscosity of the trimeric or higher polymer hydrogenated product of cyclic monoterpenoids produced in this way varies depending on the degree of polymerization, but since it generally has a high viscosity, it is better to use it as it is. It is preferable to blend it with other traction oils to improve their traction coefficients. In this case, the amount of the hydrogenated polymer is not particularly limited and may be selected as appropriate depending on the type of the hydrogenated polymer and the type of other traction oil to be blended.
Usually 0.1 to 90% by weight of the total traction fluid,
It is preferably set in a range of 2 to 60% by weight.

The degree of polymerization of the above-mentioned hydrogenated polymer is not particularly limited as long as it is at least the trimer of the cyclic monoterpenoids, but it is usually a trimer to a decamer or a mixture thereof. It is.

In addition, other traction oils that should be blended with the trimeric or higher polymer hydrogenated product of the above-mentioned cyclic monoterpenoids include those that have been conventionally used as traction drive oils, as well as those that have poor traction performance when used alone. Various types of oils can be mentioned, such as oils that are too low to be put into practical use. For example, a wide range of liquid substances can be used, such as mineral oils such as paraffinic mineral oils, naphthenic mineral oils, and intermediate mineral oils, alkylbenzenes, polybutenes, polyα-olefins, synthetic naphthenes, esters, and ethers. Among them, alkylbenzenes, polybutenes, and synthetic naphthenes are preferred. Here, the synthetic naphthene has two or three cyclohexane rings.
Alkane derivatives having one or more decalin rings and one or more cyclohexane rings, alkane derivatives having two or more decalin rings, compounds having a structure in which two or more cyclohexane rings or decalin rings are directly bonded, etc. be. Specific examples of such synthetic naphthenes include 1-cyclohexyl-1-decarylethane;
1,3-dicyclohexyl-3-methylbutane;
2,4-dicyclohexylpentane; 1,2-bis(methylcyclohexyl)-2-methylpropane; 1,1-bis(methylcyclohexyl)-2
-Methylpropane; 2,4-dicyclohexyl-
Examples include 2-methylpentane; hydrogenated limonene dimer; hydrogenated pinene dimer; and hydrogenated camphene dimer.

The traction drive fluid of the present invention contains a trimeric or higher polymer hydrogenated product of cyclic monoterpenoids as an essential component, and is prepared by further blending another liquid material (traction oil). In addition, antioxidants, rust preventive agents, cleaning dispersants, pour point depressants, viscosity index improvers, extreme pressure agents, anti-wear additives, fatigue inhibitors, antifoaming agents, oiliness improvers,
Appropriate amounts of various additives such as colorants can also be used.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Comparative Example 1 1000 g of α-methylstyrene, 50 g of acid clay, and 50 g of ethylene glycol were placed in a four-necked flask (No. 2) equipped with a stirrer, thermometer, dropping funnel, and Dimroth reflux condenser, and the mixture was stirred while stirring.
The reaction was carried out at 140°C for 2 hours. After filtering the catalyst from the reaction solution, unreacted α-methylstyrene and ethylene glycol were distilled off to a boiling point of 125-130℃/0.2mm.
900g of Hg fraction was obtained. As a result of nuclear magnetic resonance (NMR) analysis and gas chromatography analysis, this fraction was confirmed to be a mixture of 95% linear dimer and 5% cyclic dimer of α-methylstyrene.

500 ml of this fraction and 10 g of a nickel catalyst for hydrogenation (manufactured by JGC Chemical Co., Ltd.: N-113) were placed in an autoclave, and the mixture was heated at a hydrogen pressure of 50 Kg/cm ² G and a reaction temperature of 200°C.
Hydrogenation was carried out over a period of time to obtain a traction drive fluid containing 2,4-dicyclohexyl-2-methylpentane as a main component.

The properties of this product were as follows.

Kinematic viscosity 20.27cSt (40℃) 3.580cSt (100℃) Viscosity index 13 Pour point -35℃ or less Furthermore, the traction coefficient of this product was set to 60℃
Measurements were taken over a temperature range of 140°C to
As shown in the figure.

Example 1 A commercially available hydrogenated terpene resin (number average molecular weight 630,
Manufactured by Yasushi Oil Industries Co., Ltd., product name: Clearon P-85)
A fluid with the following properties was obtained by mixing 15% by weight.

Kinematic viscosity 47.96cSt (40℃) 5.554cSt (100℃) Viscosity index 13 Specific gravity (15/4℃) 0.9153 Refractive index (n _D ) 1.4973 Calculate the traction coefficient of this fluid from 60℃ to 140℃
The results are shown in Figure 1.

Comparative Example 2 552 g of toluene, 27.6 g of anhydrous aluminum chloride, and 12.6 g of nitromethane were placed in the four-necked flask of 2.
181.2 g of methallyl chloride was added dropwise over 2 hours while stirring at 0° C., and stirring was continued for an additional 1 hour to complete the reaction. After adding 75 ml of water to decompose the aluminum chloride and separating the oil layer, the oil layer was washed once with 200 ml of water and twice with 300 ml of 1N aqueous sodium hydroxide solution, and dried over anhydrous magnesium sulfate. .

Next, unreacted raw materials are distilled off using a rotary evaporator, and then distilled under reduced pressure to produce a product with a boiling point of 114 to 116
254 g of a fraction of °C/0.14 mmHg was obtained.

As a result of analysis, this fraction was found to be 2-methyl-1,2
-80% ditolylpropane, 2- of the isomerized products
Methyl-1,1-ditolylpropane was found to be 20%.

Next, 250 g of this fraction was placed in autoclave No. 1 and nickel catalyst (manufactured by JGC Chemical Co., Ltd.: N-
113) Add 20g, hydrogen pressure 70Kg/cm ² G, temperature 180
Hydrogenation was carried out at °C for 5 hours. When the catalyst was removed from the resulting reaction product and analyzed, the hydrogenation rate was 99.9% or more, and 2-methyl-1,2-
80% di(methylcyclohexyl)propane, 2
-Methyl-1,1-di(methylcyclohexyl)
It turns out that propane is 20%.

The properties of this product were as follows.

Kinematic viscosity 13.17cSt (40℃) 2.622cSt (100℃) Viscosity index −30 Specific gravity 0.8824 Refractive index (n _D ) 1.4800 Pour point −35℃ or less Furthermore, the traction coefficient of this product was set at 60℃
Measurements were made in the temperature range from to 140℃, and the results were
As shown in the figure.

Example 2 A stirrer, a thermometer, a dropping funnel, and a Dimroth reflux condenser were attached to the four-necked flask in Example 2, and 300 ml of methylcyclohexane was added as a solvent, and 10 g of activated clay (Galleon Earth NS, manufactured by Mizusawa Chemical Co., Ltd.) was added as a catalyst. I prepared it. After heating and stirring in an oil bath to 85℃, dipentene (dl-
limonene) was added dropwise over 1 hour while stirring. Thereafter, the reaction was allowed to continue for 8 hours at 85° C. while stirring. After cooling, the catalyst was filtered through a filter paper, and the solvent and unreacted raw materials were recovered using a rotary evaporator to obtain 650 g of the remaining reaction liquid.

650 g of this reaction solution and 10 g of a nickel catalyst for hydrogenation (manufactured by JGC Chemical Co., Ltd.: N-113) were placed in one autoclave, and hydrogenation was performed at a hydrogen pressure of 50 Kg/cm ² G and a reaction temperature of 150°C for 3 hours. Ivy. After cooling, the catalyst was filtered and analyzed, and the hydrogenation rate was 99% or more.

This hydrogenated product is distilled under reduced pressure and has a boiling point of 110-122℃/
400 g of a 0.2 mmHg fraction was distilled off to obtain about 250 g of a fraction consisting of 90% dipentene trimers, 8% tetramers, and 2% pentamers or higher.

This product was mixed with the product obtained in Comparative Example 2 in an amount of 10% by weight to obtain a liquid having the following properties.

Kinematic viscosity 17.53cSt (40℃) 3.092cSt (100℃) Viscosity index −35 Specific gravity 0.8887 Refractive index (n _D ) 1.4833 Pour point −35℃ or less Furthermore, the traction coefficient of this fluid was determined in the temperature range from 60℃ to 140℃. The results are shown in Figure 2.

Example 3 A stirrer, a thermometer, a dropping funnel, and a Dimroth reflux condenser were attached to the four-necked flask in Example 3, and 300 ml of cyclohexane was used as the solvent, and activated clay (Galleon Earth NS, manufactured by Mizusawa Chemical Co., Ltd.) was used as the catalyst.
I prepared 10g. 1000 g of β-pinene was added dropwise at room temperature over 4 hours while stirring. Thereafter, the reaction was allowed to continue for 30 minutes while stirring. Next, the catalyst was filtered through a filter paper, and the solvent and unreacted raw materials were recovered using a rotary evaporator to obtain 800 g of the remaining reaction liquid.

700 g of this reaction solution and 10 g of a nickel catalyst for hydrogenation (manufactured by JGC Chemical Co., Ltd.: N-113) were placed in one autoclave, and hydrogenation was performed at a hydrogen pressure of 50 Kg/cm ² G and a reaction temperature of 100°C for 3 hours. Ivy. After cooling, the catalyst was filtered and analyzed, and the hydrogenation rate was 99% or more.

This hydrogenated product is distilled under reduced pressure and has a boiling point of 108-120℃/
200 g of a 0.2 mmHg fraction was distilled off to obtain 600 g of a fraction consisting of 70% trimer, 24% tetramer, and 6% pentamer or more of β-pinene.

This product was mixed in an amount of 10% by weight with the product obtained in Comparative Example 2 to obtain a fluid having the following properties.

Kinematic viscosity 18.46cSt (40℃) 3.188cSt (100℃) Viscosity index −35 Specific gravity 0.8898 Refractive index (n _D ) 1.4841 Pour point −35℃ or less Furthermore, the traction coefficient of this fluid was determined in the temperature range from 60℃ to 140℃. The results are shown in Figure 2.

Example 4 A stirrer, a thermometer, a dropping funnel, and a Dimroth reflux condenser were attached to the four-necked flask in Example 4, and 300 ml of methylcyclohexane was added as a solvent, and 50 g of activated clay (Galleon Earth NS, manufactured by Mizusawa Chemical Co., Ltd.) was added as a catalyst. I prepared it. After heating and stirring in an oil bath to 90℃, gum turpentine oil (92% α-pinene, 5% β-pinene, 3% others)
A mixture of 500 g of dipentene (dl-limonene) and 500 g of dipentene (dl-limonene) was added dropwise over 2 hours with stirring. Thereafter, the reaction was allowed to continue for 7 hours at 110°C while stirring. After cooling, the catalyst was filtered through a filter paper, and the solvent and unreacted raw materials were recovered using a rotary evaporator to obtain 600 g of the remaining reaction liquid.

600 g of this reaction solution and 10 g of a nickel catalyst for hydrogenation (manufactured by JGC Chemical Co., Ltd.: N-113) were placed in one autoclave, and hydrogenation was performed at a hydrogen pressure of 50 Kg/cm ² G and a reaction temperature of 150°C for 3 hours. Ivy. After cooling, the catalyst was filtered and analyzed, and the hydrogenation rate was 99% or more.

This hydrogenated product is distilled under reduced pressure and has a boiling point of 105-125℃/
Distilling off 380g of fraction at 0.15mmHg, 74% of pinene-dipetene trimers, 22% of tetramers, and 4% of pentamers and above were obtained.
220 g of a fraction consisting of

This product was mixed in an amount of 10% by weight with the product obtained in Comparative Example 2 to obtain a fluid having the following properties.

Kinematic viscosity 18.11cSt (40℃) 3.160cSt (100℃) Viscosity index −33 Specific gravity 0.8890 Refractive index (n _D ) 1.4827 Pour point −35℃ or less Furthermore, the traction coefficient of this fluid was determined in the temperature range from 60℃ to 140℃. The results are shown in Figure 2.

Comparative Example 3 Ethylbenzene in a glass flask with an internal volume of 5
Add 2700g, 58g of metallic sodium, and 16g of potassium hydroxide, heat to 120℃, and add α while stirring.
-1100g of methylstyrene and 300g of ethylbenzene
was gradually added dropwise over 5 hours, and the mixture was stirred for 1 hour to carry out the reaction.

After the reaction was completed, the oil layer was cooled and separated and collected, 200 g of methyl alcohol was added thereto, and the mixture was washed three times each with 2 parts of a 5N hydrochloric acid solution and 2 parts of a saturated saline solution. Next, after drying with anhydrous sodium sulfate,
Unreacted ethylbenzene was distilled off using a rotary evaporator, and then distilled under reduced pressure to 0.06 mmHg.
1350 g of a fraction with a boiling point range of 106 to 180°C was obtained.

Next, 500 ml of this fraction was placed in an autoclave with an internal volume of 1, and nickel catalyst for hydrogenation (JGC Chemical
Co., Ltd.: N-113) 20g was added, the reaction temperature was 200℃,
Hydrogenation treatment was carried out at a hydrogen pressure of 50 Kg/cm ² G. After the reaction was completed, the catalyst was removed, the light components were stripped, and the analysis revealed that the hydrogenation rate was over 99.9%.
This hydrogenation product was confirmed to be 2,4-dicyclohexylpentane.

The properties of this product were as follows.

Kinematic viscosity 12.05cSt (40℃) 2.750cSt (100℃) Viscosity index 47 Specific gravity 0.8913 Refractive index (n _D ) 1.4832 Pour point -35℃ or less Furthermore, the traction coefficient of this product was set at 60℃
Measurements were made in the temperature range from to 140℃, and the results were
As shown in the figure.

Example 5 300 ml of methylcyclohexane as a solvent and 20 g of anhydrous aluminum chloride as a catalyst were charged into a second four-necked flask equipped with a stirrer, a thermometer, a dropping funnel, and a Dimroth reflux condenser.
Next, a mixed solution of 300 g of camphene and 50 ml of methylcyclohexane was added dropwise over 1 hour while stirring at room temperature. After that, heat it in an oil bath and heat it at 75℃ for 1 hour.
The reaction was carried out by stirring for hours. After cooling, the reaction solution was poured little by little into ice water 1 to complete the reaction. The organic layer was washed twice with 200 ml of 15% hydrochloric acid, three times with 200 ml of 10% aqueous sodium bicarbonate solution, and twice with 200 ml of water, and dried over anhydrous magnesium sulfate.

After standing overnight, the drying agent, anhydrous magnesium sulfate, was filtered off, and the solvent and unreacted raw materials were recovered using a rotary evaporator to obtain 260 g of the remaining reaction solution.

When this solution was analyzed by hydrogen flame (FID) gas chromatography (GC), the ratio of camphene dimers was 28%, trimers were 31%, tetramers were 28%, and pentamers were 13%. .

250 g of this solution and 25 g of a nickel catalyst for hydrogenation (manufactured by JGC Chemical Co., Ltd.: N-113) were placed in an autoclave No. 1, and 200 g of methylcyclohexane was added as a solvent.
ml and hydrogenated at a reaction temperature of 180° C. and a hydrogen pressure of 90 Kg/cm ² G for 5 hours. After cooling, the catalyst was removed and analysis revealed that the hydrogenation rate was over 99%. This hydrogenated product is distilled under reduced pressure and has a boiling point range of 122 to 136.
C/0.2 mmHg fraction was distilled off to obtain 160 g of a fraction consisting of camphene trimers to pentamers.

This product was mixed with the product obtained in Comparative Example 3 in an amount of 10% by weight to obtain a fluid having the following properties.

Kinematic viscosity 17.47cSt (40℃) 3.382cSt (100℃) Viscosity index 36 Specific gravity 0.9005 Refractive index (n _D ) 1.4871 Pour point -35℃ or less Furthermore, the traction coefficient of this fluid was measured in the temperature range from 60℃ to 140℃ The results are shown in Figure 3.

The traction coefficients in Examples and Comparative Examples were measured using a two-cylinder friction tester. In other words, one of the adjacent cylinders of the same size (diameter 52 mm, thickness 6 mm, driven side is a tycoon type with a radius of curvature of 10 mm, and the driving side is a flat type without crowning) is held at a constant speed (1500 rpm), and the other is held at a constant speed (1500 rpm).
Rotate continuously from 1500rpm to 1750rpm, apply a load of 7kg to the contact area of both cylinders with a spring,
The tangential force generated between the two cylinders, that is, the traction force, was measured to determine the traction coefficient. This cylinder was made of bearing steel SUJ-2 with a mirror finish, and the maximum Hertzian contact pressure was 112 Kgf/mm ² .

In addition, when measuring the relationship between traction coefficient and oil temperature, the oil temperature was varied from 60℃ to 140℃ by heating the oil tank with a heater.
This is a plot of the relationship between traction coefficient and oil temperature at a slip rate of 5%.

As is clear from FIGS. 1 to 3, the traction drive fluid of the present invention can maintain a high traction coefficient, particularly in a high temperature range, and is suitable as a traction drive fluid.

[Effects of the Invention] The traction drive fluid of the present invention, which contains a hydrogenated trimer or higher polymer of cyclic monoterpenoids, has a traction coefficient over a wide temperature range from room temperature to high temperature. high, which improves transmission efficiency. As a result, it is possible to reduce the size and weight of the traction drive device, extend its lifespan, and increase its output, which can be widely used in various mechanical products such as continuously variable transmissions for automobiles and industrial use, and even hydraulic equipment. .

In addition, the hydrogenated trimeric or higher polymers of the above-mentioned cyclic monoterpenoids can increase the traction coefficient just by blending a small amount with other fluids, providing various excellent traction drive fluids. It is possible to do so.

[Brief explanation of the drawing]

1 to 3 are graphs showing temperature changes in traction coefficients of traction drive fluids obtained in Examples and Comparative Examples.

Claims (1)

[Scope of Claims] 1. A traction drive fluid characterized by containing a hydrogenated polymer of trimer or higher of cyclic monoterpenoids. 2. The traction drive fluid according to claim 1, wherein the cyclic monoterpenoids are menthadienes, pinenes, or bicyclo[2.2.1]heptanes. 3. The traction drive fluid according to claim 1, which contains a hydrogenated trimeric or higher polymer of cyclic monoterpenoids in a proportion of 0.1 to 90% by weight.