JPH0823029B2 - How to transmit power - Google Patents

Description

The present invention relates to an improved power transmission method using a traction drive fluid composition having a high viscosity and an excellent traction coefficient, and more particularly to a power transmission method using a composition comprising a mixture of hydrocarbons represented by a specific chemical formula as the traction drive fluid.

The traction drive power transmission method is a method of transmitting power by the shear force of the oil film of the traction drive fluid formed between rotating bodies (rolling bodies) rotating relative to one another. This method is used in traction drive devices, such as power transmission or transmission devices for automobiles, including continuously variable transmissions, variable speed transmissions, and torque converters. The traction drive fluids used in such devices are required to have a high traction coefficient.

[Background Art] Many compounds have been proposed as fluids for traction drives. For example, U.S. Pat.
Others in No. 8 include decalin, perhydroanthracene,
Polycyclohexyls, bicyclohexyls, dicyclohexyls, hydrogenated α-methylstyrene dimer, adamantanes, alkylbenzenes, and hydrogenated styrenated cumene have been proposed.

With the recent development of automobile-related technologies, the traction drive devices themselves have become smaller and are being used under increasingly high speed and high load conditions, and therefore the operating conditions for the traction drive fluids used in such devices are becoming higher in temperature and more severe.

However, among the compounds proposed so far as described above, not many have been put to practical use due to reasons such as the traction coefficient being unsuitable for practical use and the difficulty in obtaining raw materials for industrial-scale implementation, etc. The only one that can be cited as being practical is 2,4-dicyclohexyl-2-methylpentane, proposed in U.S. Patent No. 3,994,816.

In traction drive devices, power is transmitted by the shear force of the oil film of the traction drive fluid formed between the rotating bodies (rolling bodies) that rotate relative to one another, and in order to maintain the film thickness of the fluid, a certain degree of viscosity is required even under high temperature conditions. For this reason, there is an increasing demand for high viscosity fluids.
In addition to viscosity, the traction coefficient must also be high.

However, among the few compounds mentioned above that have been put to practical use, 2,4-dicyclohexyl-2-
Even with methylpentane, the traction coefficient is certainly high to a certain extent, but the viscosity is not necessarily satisfactory. That is, the viscosity (@100°C) of this compound alone is 3.6 cS.
t (10 ^-2 cm ² /sec). Therefore, viscosity index improvers such as polymethacrylate and polyisobutylene are added,
It has been proposed to increase the viscosity of the fluid. However, although the addition of these viscosity index improvers does increase the viscosity, they also decrease the traction coefficient. Furthermore, when used for a long period of time under severe conditions, the addition of these additives can cause deterioration and a decrease in viscosity, which can be undesirable. Traction drive fluids are
From the viewpoint of oxidation reaction, the conditions are extremely severe, and therefore the demands for oxidation stability are also extremely strong.

Incidentally, various lubricating oils have been proposed and put into practical use for use in rotating members such as rotary bearings that rotate substantially independently of each other. Examples of such lubricating oils include a mixture of hydrogenated linear dimer and hydrogenated linear trimer of α-methylstyrene, as disclosed in U.S. Patent No. 3,925,217. However, the so-called lubricating oils
In stark contrast to traction drive fluids, lubricants improve the sliding between rotating parts, allowing them to rotate freely or independently of one another, i.e., ensuring their free and independent movement. Their effects are completely different from those of the traction drive fluids of the present invention. Therefore, it is unthinkable to predict the effects of the power transmission method of the present invention from the effects of such so-called lubricants. In other words, so-called lubricants used for rotating parts that essentially rotate independently of one another, such as rotating bearings, are generally considered unsuitable as traction drive fluids. Therefore, a person skilled in the art would not predict from the disclosure of the above publication that the lubricant described therein would be useful as a traction drive fluid.

Furthermore, U.S. Patent Nos. 3,595,796 and 3,598,740 disclose the use of α-methylstyrene trimers in traction drive fluids. However, the oligomers described in these publications are all so-called hydrindane-type cyclic compounds or compositions mainly composed of these cyclic compounds. In light of the increasingly stringent requirements for traction drive fluids mentioned above, the present inventors conducted further research and found that the cyclic compounds described in the above publications, particularly the cyclic trimers and cyclic tetramers, have low oxidation stability and are far from meeting the stringent requirements of recent years.

DISCLOSURE OF THE INVENTION An object of the present invention is to improve fluid compositions for traction drives comprising 2,4-dicyclohexyl-2-methylpentane (hereinafter sometimes referred to as "DCHP"). More specifically, an object of the present invention is to provide a novel fluid composition for traction drives which has a superior traction coefficient, higher viscosity, and superior oxidation stability compared to 2,4-dicyclohexyl-2-methylpentane, a typical compound that has been used in practical applications up to now.

That is, the present invention provides a composition comprising 40 to 80% by weight of 2,4-dicyclohexyl-2-methylpentane and 20 to 60% by weight of compounds represented by the following formulas (I) to (IV), wherein the weight ratio of the total of the compounds represented by the following formulas (III) and (IV) to the total of the compounds represented by the following formulas (I) and (II) is 0.5 or less, and the viscosity (at 100°C) is 5.0 to 15.0 c
The present invention relates to a method for transmitting power ^by the ^shear force of an oil film formed between relatively rotating bodies (rolling bodies) of a traction drive fluid composition, characterized by using a traction drive fluid having as a base stock a composition having a viscosity in the range of St (10-2 cm2/sec). The compounds of the present invention represented by formula (I) and formula (II), i.e., polycyclohexylalkanes, and the compounds of the present invention represented by formula (III) and formula (IV), i.e., perhydroindan derivatives, are shown below.

The compounds represented by formula (I) or (II) above are extremely viscous liquid or solid compounds and are not suitable for use as traction drive fluids by themselves. However, when mixed with 2,4-dicyclohexyl-2-methylpentane, the viscosity of the fluid can be increased, and the traction coefficient is not reduced but rather improved due to the synergistic effect of the components.

The compounds of formula (I) to formula (IV) are mixed in a total amount of 20 to 60% by weight with 2,4-dicyclohexyl-2-methylpentane. If the amount is less than 20% by weight, no improvement in viscosity can be expected, and the synergistic effect of increasing the traction coefficient cannot be expected. Conversely, if the total amount exceeds 60% by weight, the viscosity becomes too high, which is undesirable. More preferably, the upper limit of the amount of the compound of formula (I) mixed is 40% by weight, and the upper limit of the compound of formula (II) is 15% by weight.
Although the compounds of I) can be mixed individually, it is preferable to use both of them in combination for the purpose of the present invention.

Furthermore, since the compounds represented by the formulas (III) and (IV) have poor oxidation stability, the ratio of the compounds represented by the formulas (III) and (IV) to the total of the compounds represented by the formulas (I) and (II) is
It is necessary that the total weight ratio of the compounds represented by formulas (III) and (IV) is 0.5 or less. If the weight ratio of the compounds represented by formulas (III) and (IV) is more than 0.5, the oxidative stability of the resulting fluid composition will be reduced, which is undesirable.

In addition, in accordance with the recent requirements for traction drive fluids for automotive transmissions, the traction drive fluid composition of the present invention preferably has a viscosity (at 100°C) in the range of 5.0 to 15.0 cSt ( ^{10-2 mc2} /sec).

In producing the fluid composition of the present invention, the 2,4
The proportions of the 2-dicyclohexyl-2-methylpentane, the compound of formula (I) and the compound of formula (II) may be appropriately selected.

2,4-Dicyclohexyl-2-methylpentane, the compounds represented by the above formulas (I) and (II), can be, for example, α-
They can be easily produced by polymerizing methylstyrene or by pyrolyzing poly(α-methylstyrene) to obtain the corresponding aromatic hydrocarbons, triarylalkanes and tetraarylalkanes, which are then hydrogenated.

However, when produced from α-methylstyrene or a polymer thereof as described above, the compound represented by the above formula (III) or (IV), which is a cyclic compound, is likely to be produced as a by-product (although what is directly obtained is an aromatic hydrocarbon, it is shown as the corresponding hydride).

As mentioned above, these cyclic compounds have poor oxidation stability and are therefore undesirable for the purposes of the present invention. However, these compounds and the compounds of formulas (I) and (II) have almost the same molecular weights and similar boiling points, so separation by distillation is not easy either before or after hydrogenation. Therefore, when producing α-methylstyrene, it is essential to prevent these compounds from being produced as by-products.

Therefore, when α-methylstyrene is produced by polymerization, it is preferable to appropriately select polymerization conditions, such as using a solid acid catalyst such as acid clay, activated clay, silica-alumina, montmorillonite clay, or silica gel in an amount of 2 to 30% by weight based on the raw material monomers, adding an oxygen-containing compound such as water, a dihydric alcohol, or an ether as a reaction modifier in an amount of 30 to 300% by weight based on the catalyst, and conducting the reaction at a temperature in the range of 30 to 150° C. The reaction can be carried out in either a batch or continuous manner.

Triarylalkanes and tetraarylalkanes obtained by polymerizing α-methylstyrene are subjected to nuclear hydrogenation. This nuclear hydrogenation reaction is achieved by contacting a mixture of the hydrogenation raw material and hydrogen with a conventionally known aromatic hydrogenation catalyst, such as nickel, nickel diatomaceous earth, Raney nickel, platinum, platinum-alumina, rhodium, or rhodium-alumina, under reaction conditions of 250°C or less and 30 kg/ ^cm² or more. This nuclear hydrogenation reaction also hydrogenates the ethylenic double bonds. The hydrogenation rate is at least 80%, preferably 90% or more, and more preferably 95% or more. It is not only difficult to completely eliminate aromatic hydrocarbons or compounds with double bonds, for example, to 1% or less, but also unnecessary because even small amounts do not impede the objectives of the present invention.

The fluid composition of the present invention may contain any of the additives conventionally known for lubricating oils, such as antioxidants (e.g., phenolic compounds such as 2,6-tert-butyl-p-cresol, amine compounds such as phenyl-α-naphthylamine, sulfur compounds such as sulfides and disulfides, and organometallic compounds such as zinc dialkyldithiophosphate; extreme-pressure additives (e.g., sulfur compounds such as sulfurized oils and fats, phosphorus compounds such as phosphates and phosphites, and organometallic compounds such as thiophosphates and thiocarbamates); rust inhibitors (e.g., amines, esters, and metal salts); viscosity index improvers (e.g., poly(meth)acrylate, polyisobutylene, or hydrogenated products thereof); and antifoaming agents (e.g., silicone compounds). For example, the antioxidants may be added to the fluid composition of the present invention in an amount of 0.01 to 5 wt %.

Furthermore, it can also be used as a traction grease by mixing it with organic or inorganic thickeners known for use in greases, such as metal soaps, synthetic polymers, polyureas, organosiloxanes, clay, bentonite, and colloidal silica.

Furthermore, the fluid composition of the present invention can be used as a traction drive fluid by adding conventionally known compounds in any proportion, and can also contain the above-mentioned cyclic dimer that is a by-product during the polymerization of α-methylstyrene, within the range in which the effects of the present invention are achieved.

[Best Mode for Carrying Out the Invention] The present invention will be described in detail below with reference to the following examples.

Example 1 Activated clay (Galeonite 236,
Mizusawa Chemical Co., Ltd.) 200cc of catalyst is used in the circulation system equipment.
α-Methylstyrene was polymerized. The catalyst was prepared in advance using 2.
The activity was adjusted by infiltration with 2 times the volume of methyl cellosolve for 3 hours. The reaction conditions were as follows:

Reaction temperature: 45°C S/V: 2.4hr ^-1 circulation/new charge: 2.4 (vol/vol) From the resulting reaction mixture, fractions with a boiling point of 400°C or less (at atmospheric pressure) were distilled off, and fractions with a C ₂₇ or more were recovered.

(Yield: 50 wt%) This fraction was treated with 2 wt% of nickel diatomaceous earth catalyst (trade name: N
To the mixture was added HCl (N-113, manufactured by Nikki Chemical Co., Ltd.), and the mixture was subjected to hydrogenation treatment in an autoclave at 200°C and 80 kg/ ^cm² for 8 hours.
The resulting product was analyzed using GC, GPC and a GC mass spectrometer, and was found to have the composition shown in Table 1.

The kinematic viscosity at 100°C of the composition obtained by mixing 49.5 parts by weight of the above components with 50.5 parts by weight of DCHP was 8.3 cSt (10 ^-2 c
m ² /s), pour point is -25°C and traction coefficient is 0.10
The oxidation lifetime (RBOT method) was 340 minutes.

(Test Method) Traction coefficient measurement conditions: Disc rotation speed 1500 rpm, average Hertzian pressure 92.5 kgf/ ^mm² , slip ratio 2%, temperature 25°C. Oxidation stability (oxidation life): Measured by the RBOT method (based on ASTM D-2772).

Oxidation test conditions: Sample weight 50 g, Temperature 150°C, Initial oxygen pressure 6.3 kg/ ^cm², Oxidation catalysts copper and iron. The unit is minutes; the longer the time, the longer the oxidation life. In the oxidation stability test, 0.5 wt% of 2,6-di-tert-butyl-p-cresol was added to each sample as an antioxidant.

Example 2 α-Methylstyrene was reacted under the same conditions as in Example 1, except that the reaction temperature was set to 65°C.

From the obtained product, fractions with a boiling point of 250°C (at atmospheric pressure) or less were distilled, and fractions with _C18 or more were recovered (yield 90 wt
%).

To this fraction was added 2 wt % of N-113 catalyst, and the mixture was hydrogenated in an autoclave at 200°C and 50 kg/ ^cm² for 5 hours. The resulting product was analyzed in the same manner and found to have the composition shown in Table 2.

The kinematic viscosity of this composition at 100°C is 6.7 cSt and the pour point is -27.
The traction coefficient was 0.097 at 5°C, and the oxidation life was 300 minutes.

Comparative Example 1: In a separable flask equipped with a condenser and a stirrer, 165 cc of α-methylstyrene dimer recovered from the _C18 or higher fraction obtained in Example 2 and 15 cc of methyl cellosolve were added. 3 cc of activated clay (Galleon Earth NSR, manufactured by Mizusawa Chemical Industries, Ltd.) dried at 120°C for 3 days was added.
Add g and raise the temperature to 115°C while stirring.
While maintaining the temperature at 115-120°C, add 420 cc of α-methylstyrene to the
Infuse at a rate of 100 cc/hr for 3 hours.
After the reaction was completed, the reaction mixture was separated from the catalyst by filtration.

From the resulting reaction mixture, fractions with a boiling point of 250°C or less were distilled off, and fractions with a _C18 or higher were recovered (yield 85 wt%).
To this fraction, 2 wt % of N-113 catalyst was added, and hydrogenation treatment was carried out in an autoclave at 200°C and 50 kg ( _H2 )/ ^cm2 for 5 hours. The obtained product was analyzed in the same manner, and the following was found:
The composition was as shown in Table 3.

The product has a kinematic viscosity of 4.6 cSt at 100°C and a pour point of -40
°C, the traction coefficient was 0.090, and the oxidation life was 290 minutes.

Comparative Example 2 α-Methylstyrene was reacted under the same conditions as in Example 1, except that the reaction temperature was set to 65°C.

From the obtained product, fractions with a boiling point of 250°C (at atmospheric pressure) or less were distilled, and fractions with _C18 or more were recovered (yield 90%).
%).

200 cc of this fraction, 5 cc of methyl cellosolve, and 3 g of activated clay (trade name: Galleon Earth NSR, manufactured by Mizusawa Chemical Industry Co., Ltd.) dried at 120°C for 3 days were added to a 1000 ml container equipped with a condenser and a stirrer.
The mixture was placed in a separable flask and stirred at 80°C for 1 hour.

After the reaction was completed, the catalyst was separated by filtering the reaction mixture.

To this reaction product, 2 wt % of N-113 catalyst, a hydrogenation catalyst, was added, and the mixture was hydrogenated in an autoclave at 200°C and 50 kg/ ^cm² for 5 hours. The resulting product was analyzed in the same manner, and the composition was as shown in Table 4.

The kinematic viscosity of this composition at 100°C was 8.9 cSt (@100°C), the pour point was -27.5°C, and the traction coefficient was 0.096. The oxidation life was also low at 210 minutes.

Comparative Example 3 2,4-dicyclohexyl-2-methylpentane at 100°C
The kinematic viscosity was 3.6 cSt, the pour point was -42.5°C, and the traction coefficient was 0.087. The oxidation life was 310 minutes.

The results of the above examples and comparative examples are summarized in Table 5.

(Summary of Experimental Results) From the results shown in Table 5 above, it can be seen that the compositions of the Examples are clearly improved in kinematic viscosity characteristics, traction coefficient, oxidation stability, etc. compared to the compositions of the Comparative Examples.
The traction coefficient is improved compared to the comparative example containing only methylpentane. This indicates a synergistic effect of the components. The fluid composition of Comparative Example 1 has a relatively high traction coefficient but a low viscosity due to an insufficient content of the compounds of formulas (I) to (IV). Furthermore, the fluid composition (Comparative Example 2) containing a high proportion of the compounds of formulas (III) and (IV) exhibits poor oxidation stability.

Claims (3)

[Claims] [Claim 1] A method for transmitting power by the shear force of the oil film of a traction drive fluid formed between relatively rotating bodies, characterized by using a traction drive fluid having as its base stock a composition consisting of (1) 40 to 80 weight % of 2,4-dicyclohexyl ^- 2-methylpentane and (2) 20 to 60 weight % of compounds represented by the following formulas (I) to (IV), wherein the weight ratio of the total of the compounds represented by the following formulas (III) and (IV) to the total of the compounds represented by the following formulas (I) and (II) is 0.5 or less, and the viscosity (at 100°C) is in the range of 5.0 to 15.0 cSt ( ^10-2 cm2/sec). 2. The composition contains 40% of the compound of formula (I).
2. The method of transmitting power according to claim 1, wherein the compound of formula (II) is contained in an amount of 15% by weight or less. 3. The method of transmitting power according to claim 1, wherein said fluid contains 0.01 to 5 weight percent of an oxidation stabilizer.