JPS59191797A - Fluid for traction drive - Google Patents

Abstract

PURPOSE:To provide a fluid for fraction drive which contains an ester having at least two cyclohexyl groups in the molecule and has a high traction coefficient. CONSTITUTION:The fluid for traction drive contains at least one compd. selected from among esters containing in the molecule at least two cyclohexyl groups which may have an alkyl group. The esters include cyclohexyl ester of cyclohexylcarboxylic acid, dicyclohexyl ester of cyclohexyldicarboxylic acid, dicyclohexyl ester of fumaric acid and dicyclohexyl ester of phthalic acid. The ester is obtained, e.g., by reacting a cyclohexyl group-containing carboxylic acid such as cyclohexylcarboxylic acid with cyclohexyl group-containing alcohol such as cyclohexyl alcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a traction drive fluid. More specifically, it relates to a novel traction drive fluid containing an ester having two or more cyclohexyl groups in the molecule and having a high traction coefficient. A thing is invented, manufactured, and made.The principle of its operation (case 1.
The driven rotor is pressed against the drive rotor, and the driven rotor is rotated by the friction of point or line contact between the two rotors, thereby transmitting power.

The contact portion of both rotating bodies is constantly supplied with a traction drive fluid (hereinafter abbreviated as fluid). This fluid lubricates both rotating bodies when there is no load,
200,000 to 400,000 psi (1,40,000 to 30,000 Kq) under load
/crA ), it instantly becomes a solid-like state and becomes a power transmission medium.

The power transmission performance of a fluid is generally determined by the traction coefficient ft
As shown in FIG. 1, it is defined as the ratio of tangential force (or traction force) Ft and normal load Pn.

ft2F, /Po...(1) By transforming equation (1), equation (2) is obtained.

F, = ftXP, (2) The following can be understood from this equation. That is, when the normal load Po is set to a certain value, the tangential force 1d increases as more fluid with a higher coefficient ft is used, so the device can be made smaller and lighter.

When the necessary tangential force Ft'Th is set to a certain value 1, the normal load P increases as more fluid with a higher traction coefficient ft is used. Since it is possible to lower the rolling fatigue wear of the rotating body, it is also possible to reduce the rolling fatigue wear of the rotating body. Efforts are therefore constantly being made to improve the traction coefficient as much as possible.

More than 10 types of products have been proposed as fluids for these traction drives, including naphthenic mineral oils, hydrogenated polyolefins, and non-chlorohexyl alkanes.
Although it has been empirically recognized that some of these have high traction coefficients, the factors that lead to the high coefficients have not been clearly investigated.

The mechanism of fluid action is considered to be so-called elastohydrodynamic lubrication, which began with Eyring's viscosity theory (1936), Gubrin (1949), and Dowson.
(1960), Maxwell's viscoelastic model (1,
Although various theories have been developed, such as 968), there are few suggestions regarding the molecular design necessary to increase the traction coefficient of fluids.

As shown below, the inventors investigated the movement of molecules constituting a fluid under load in Sections 1 to 1, and searched for a method for synthesizing molecules suitable for Traxy+1 drive.

As a group of fluid molecules gradually enters a narrower space from the opening A to the contact portion B in the apparatus shown in FIG. 1, the molecular spacing becomes closer and the density increases. The ideal is for fewer molecules to fall out of the group during this approach. If there are many molecules that fall off, the oil film that forms will be thin and flimsy, and there is a risk of damage due to dry friction.
There is. Since 1 does not have the force of trying to enter the molecule by itself and simply follows the movement of the fluid, K needs some kind of hook or entanglement between the molecules so that it does not fall out.

Next, the molecular group that entered the contact area
It is said that it is subjected to a pressure of i, but at this time it is given energy, so it generates heat and the molecular motion becomes more intense. Even under these conditions,
Ideally, each molecule should be in a state where it cannot move.

At this time, the occurrence of a misalignment in the arrangement of the medium molecules indicates that the medium is a so-called fluid, and such a substance cannot be used as a medium for power transmission. In order for media molecules to exhibit such behavior, it is necessary for the molecules to be caught or entangled with each other.

Furthermore, when passing through the contact area, the molecular group is released from pressure, so the molecular spacing increases, and the individual molecules can disperse and regain their original fluid state.

In order for media molecules to behave as described above, it is important that the molecules meet the following conditions.

(1) The shape of the molecule is preferably irregular and curved. This is because holes are formed in the molecules, and when the molecules come close to each other, parts of the molecules fit into them, causing them to get caught, overlap, or become entangled.

(2) It is desirable that the molecules be short molecules. long chain 4
- Molecules are constantly entangled, increasing the viscosity of the fluid, which is undesirable because it causes loss of power.

(3) Thick molecules are preferable. When loaded, a thick oil film forms, causing dry friction between the two wheels and eventually causing wear and tear.

(4) Molecules must have rigidity. This is because the above-mentioned preferred three-dimensional structure needs to remain unchanged even when subjected to external pressure.

(5) The molecule must be mechanically, thermally and chemically stable.

(6) From a practical standpoint, it is desirable that molecules be available at low cost and in large quantities.

The present inventors synthesized a molecule in line with the above-mentioned purpose by linking multiple cyclohexyl groups with ester bonds, and succeeded in obtaining a fluid with a high traction coefficient. This fact supports the validity of the molecular design.

Specifically, the present invention relates to a traction drive fluid containing one type or a mixture of two or more types selected from esters having two or more cyclohexyl groups, which may have an alkyl group, in the molecule.

The ester of the present invention has a plurality of cyclohexyl groups that may have an alkyl group. The number of cyclohexyl groups is usually 3 for each f42 in order to have an appropriate viscosity change as a traction drive fluid, but even if the ester has a larger number of cyclohexyl groups, it can be diluted as appropriate. It can be used with low viscosity. The alkyl group i41''! or more can be substituted with a J-cyclohexyl group, but a C1-C3 alkyl group such as a methyl group, an ethyl group, or a zologyl group is preferred.

In addition, if the compound of the present invention has a plurality of cyclohexyl groups and an ester group, it can also have an aromatic nucleus and an olefinic double bond. Furthermore, two or more types of esters can be used in combination.

In the present invention, one type or a mixture of two or more of these esters is appropriately selected and used. If it is liquid at room temperature, it can be used as a traction drive fluid, and even if it is solid at room temperature, it can be mixed and dissolved in an appropriate fluid and used in liquid form.

Specifically, to explain the ester of the present invention, the acid moiety is cyclohexyl carboxylic acid such as cyclohexyl monocarboxylic acid and cyclohexyl monocarboxylic acid. These include phosphoric acids, cyclohexyl group-substituted fatty acids such as cyclohexyl acetic acid, phthalic acid, fumaric acid, succinic acid, and alkenylsuccinic acid.

Further, the alcohol moiety includes cyclohexyl alcohol, methylcyclohexyl alcohol, and the like.

Therefore, the esters of the present invention include cyclohexylcarboxylic acid cyclohexyl ester, cyclohexyl dicarboxylic acid nocyclohexyl ester, fumaric acid nocyclohexyl ester, phthalic acid nocyclohexyl ester,
alkenylsuccinic acid dicyclohexyl ester, etc., or a mixture thereof.

Such esters can be obtained, for example, by reacting a carboxylic acid having a cyclohexyl group such as cyclohexyl 7-carboxylic acid with an alcohol having a cyclohexyl group such as cyclohexyl alcohol to form an ester. Furthermore, by reacting with an aromatic carboxylic acid having an aromatic nucleus such as aromatic carboxylic acid, cyclohexyl carboxylic acid, cyclohexyl alcohol, or an aromatic hydrocarbon having a hydroxyl group such as phenol, aromatic It can be obtained by obtaining an ester having a nucleus and then performing nuclear hydrogenation on the aromatic nucleus of the ester.

The esterification reaction is (1) esterification method using an acid catalyst (2) reaction of acyl halocenide and alcohol, (
3) Reaction of acid anhydride and alcohol, (4) Reaction of carboxylate and alkyl halide, and (5) Transesterification are known, and it is possible to synthesize by any of these methods. As a result of comparing their advantages and disadvantages, it was found that the so-called modified Fisher method is the most appropriate.

That is, in this method, carboxylic acid is mixed with about 2 times the equivalent of cyclohexyl alcohol and stirred at 180 to 190°C for several hours to over 10 hours without adding an acidic catalyst. The water is azeotroped with chlorohexyl alcohol and expelled from the reaction system.
Dean-Stark (Dean-3tark) 1 trap is used for fractionation. Although the reaction rate is lower than when using a catalyst, it can be compensated for by increasing the reaction temperature, and catalyst removal after the reaction is completed. sum,
Since processing steps such as washing with water can be omitted, the total time required can be reduced. It has advantages such as being able to prevent slivers and coloration of esters. When carrying out esterification of cyclohexyl alcohol, acidic catalysts cannot be used due to the fatal drawback of dehydrating and ring-opening the cycloalcohol.Other esterification methods have advantages and disadvantages; It is not necessarily a good idea to adopt these.

Nuclear hydrogen addition includes nickel, nickel oxide, nickel-diatomaceous earth, Raney nickel, nickel-steel, platinum, platinum oxide, platinum-activated carbon, platinum-rhodium, platinum-alumina, platinum-lithium-alumina, rhodium-activated carbon, tsucladium, co-glue. By bringing a mixture of ester and hydrogen gas into contact with well-known aromatic nuclear hydrogenation catalysts such as ruth, Raney cobalt, ruthenium, tungsten sulfide-nickel sulfide-alumina, etc. under high pressure at 250°C or less. It can be achieved. This hydrogenation reaction may be carried out either batchwise or continuously. Nuclear hydrogen addition lowers the aromatic residual rate to less than 2.0 cents, especially when it is very efficient.
It is desirable to set it below 57 or 1 cent in order to prevent a decrease in the traction coefficient.

Known additives such as 2,6-tert-butyl para-cresol, tricresyl, etc. are added to the fluid thus obtained for the purpose of improving properties such as oxidative stability, thermal stability, anti-wear properties and anti-corrosion properties. Phosphates, thiophosphates, phosphoric esters, etc. can be added as necessary. For the purpose of adjusting the viscosity, mineral oils can be mixed in any proportion and homogenized before use.

Furthermore, the ester of the present invention can be used by mixing it with a conventionally known fluid for tracunyon drive in any proportion. Representative examples of such fluids include Japanese Patent Laid-open No. 5
The nuclear hydrogen additive of noaryl alkane described in Japanese Patent Application Laid-open No. 5-43108, the ζζ trinomial ring compound described in Japanese Patent Application Laid-open No. 55-40726, and the product sold under the trade name "Santotrack" by Monzanto. A linear dimer of α-methylstyrene, or a nuclear hydrogenated product of this analog.

The present invention will be explained in more detail below using Examples and Comparative Examples.

Actual 8 cases 1. (Production of non-chlorohexyl ester 4) A 500 ml four-neck round bottom flask equipped with a Dean-Stark trap, a backflow condenser, a nitrogen gas blowing tube and a stirrer was set on a mantle heater, and cyclohexylcarboxylic acid 121HF was added. (1 mol) Tonclohexanol 200? (2 moles) is staked out. Gradually increase the temperature
-Continue stirring while stirring to dissolve and homogenize the carboxylic acid, then raise the temperature further to 180°C to 185°C.
Keep it. As esterification 11- progresses, the water produced is azeotropic with cyclohexanol, reaches the condenser, is cooled, becomes liquid and flows down, the water is captured in the Dean-Stark trap, and the cyclohexanol is refluxed into the flask. . During the reaction, nitrogen gas is continuously blown in small amounts. The reaction is completed in about 16 hours. The contents of the flask were transferred to a distillation apparatus, and unreacted cyclohexanol was first separated and removed, and then 3 tan
The desired ester is obtained by removing the cyclohexylcalcinic acid under reduced pressure of Hg. Calculated from the yield, approximately 95% of the L fc '/chlorohexylcarboxylic acid used
It turns out that there was a reaction.

In place of cyclohexyl caldic acid, the acids used are fumaric acid, 0-phthalic acid, alkenyl cono-phosphoric acid obtained by adding maleic anhydride to propylene tetramer, and alkenyl cono-phosphoric acid obtained by adding maleic anhydride to butene trimer. Co-phosphoric acid was selected and reacted with cyclohexanol in the same manner to obtain esters shown in Table 1.

12 Example 2 (Production of cyclohexylcarboxylic acid nocyclohexyl ester) Commercially available cyclohexylcarboxylic anhydride 1
54 q (1 mol) and cyclohexanol 400f7 (
4 mol) was reacted in the same manner as in Example 1 to obtain the title ester. From the yield and analysis of distillate and pot residue,
It was confirmed that about 95 units of carboxylic acid anhydride were esterified.

Example 3 (Aromatic nuclear hydrogenation of phthalic acid synchlohexyl ester) 330f (1 mol) of commercially available 0-phthalic acid synchlohexyl ester (powder) was collected in an autocube (1 t), and after adding 30 fff of Raney nickel, hydrogen was added. Gas was injected under pressure to 35 Kg/Cd, then while stirring, hydrogen gas was added to maintain the pressure at 35-40 Kg/cwt, held at 60°C for 2 hours, and then heated to 180°C over 3 hours. Warm outside at 180~2
Heat at 00°C for 4 hours. After that, the pressure is 35-40K.
Cool to room temperature while maintaining the temperature at y/crl. Release the water gas, take out the contents and sieve to remove all the catalyst.

The mixture was then passed through a vacuum distillation apparatus to remove all light decomposition products.

The properties of the esters obtained in each of the above Examples, as well as comparative examples such as hydrogenated polybutene and petroleum-based naphthenic mineral oil, were measured and are shown in Table 1.

The traction coefficient was measured using a 4-cylindrical friction tester at a driving shaft rotation speed of 1500 rpm and a driven shaft rotation speed of 147O.
Measurements were made with rpm, slip ratio factor 2, load 207 to 7, and oil temperature at room temperature. Other general properties were based on the JIS method.

15-581- (*) Since the traction coefficient of a solid cannot be measured, it was mixed with an ester whose traction coefficient was known to form a liquid, the traction coefficient was actually measured, and it was calculated from the mixing ratio by proportional calculation. Since it is said that a weighted average value holds true for the traction coefficient of a mixture, FTC is based on that.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an aspect of the traction drive. PTl ・Normal load Ft: Tangential force A:
Opening B: Contact portion Patent applicant: Japan Petrochemical Co., Ltd. Representative: Hajime Maejima, patent attorney 18-584-

Claims (3)

[Claims] (1) A fluid for tracunyon drive containing one type of compound or a mixture of two or more types of compounds selected from esters having two or more cyclohexyl groups, which may have an alkyl group, in the molecule. (2) The fluid for a traction drive according to claim 1, wherein the ester is nclohexylnocargenic acid nonchlohexylene ester. (3) The tracunyong drive fluid according to claim 1, wherein the ester is an ester obtained by aromatic nuclear hydrogenation of non-chlorohexyl heptalate ester.