JPS62153395A - Traction fluid - Google Patents

Abstract

PURPOSE:To obtain a traction fluid which has a high coefficient of traction and is relatively inexpensive, by using a blend of a specified diester compd. or its derivative and a branched poly-alpha-olefin as a base oil. CONSTITUTION:A traction fluid contains a blend of a diester compd. of the formula or its derivative and a branched poly-alpha-olefin as a base oil. In the formula, A is an ester linkage of -COO- or -OOC-; n is 1-6; R1 is H or a 1-8C alkyl; R2 is a 1-3C alkyl. n is pref. 1-3. When n is O, the coefficient of traction is low, while when n is 7 or above, the viscosity is too high. thus, the case where n is 0 or 7 is not preferred. The poly-alpha-olefin has a quaternary or teriary carbon atom in its main chain. Examples thereof are polymers of a 3-5C alpha-olefin and hydrogenated products among which polybutene, polyisobutylene and hydrogenated products thereof are particularly preferred.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a traction fluid, more specifically a traction fluid based on a diester having two cyclohexyl rings or a derivative thereof and a branched polyalphaolefin. This invention relates to a traction fluid formulated as an oil.

(Prior Art) In automobiles and industrial machines, traction drive power transmission devices that transmit power to driven parts using traction drive mechanisms have attracted attention, and research and development have been actively promoted in recent years. What is traction drive mechanism?
This is a power transmission mechanism that uses rolling friction, etc., and does not use gears as in conventional systems, reducing vibration and noise, and allowing for extremely smooth speed changes at high speeds. Improving the fuel efficiency of cars is an important issue in the automobile industry, but if a traction drive is applied to a car's transmission to make it continuously variable, the engine can always be operated in its highest fuel efficiency range, making it easier to replace conventional transmission systems. It is said that fuel consumption can be reduced by more than 20%. Recent research results include the development of materials with high fatigue strength and theoretical analysis of traction, and the correlation between the traction coefficients of traction fluids at the level of the molecular structure of their components is gradually being clarified. Here, the traction coefficient refers to the contact area of the rotating bodies that contact each other in a rolling friction type power transmission device.
It is defined as the ratio of the traction force generated by sliding to the normal load.

The traction fluid must be a lubricating oil with a high traction coefficient, and it has been confirmed that those with a naphthene ring molecular structure exhibit high performance.A commercially available product is Monsanto's "Sand Truck ■". is widely known. As a traction fluid having a naphthene ring, Japanese Patent Publication No. 47-J5783 discloses di(cyclohexyl)alkane or dicyclohexane. This patent states that the alkane compound is perhydrogenated (
It is stated that the traction coefficient of a fluid containing an alpha methyl) styrene polymer or a hydrindane compound is at a high level. Furthermore, JP-A-59-1
Publication No. 91797 discloses a traction fluid containing an ester compound having a naphthene ring, in which an ester obtained by aromatic nuclear hydrogenation of cyclohexyldicarboxylic acid dicyclohexyl ester or phthalic acid dicyclohexyl ester is used as a traction fluid. It is preferred as such.

(Problems to be Solved by the Invention) As mentioned above, in recent years the automobile industry has been actively promoting the development of continuously variable transmissions. Fluids with as high a traction coefficient as possible are desired because they can increase the permissible transmission force, making it possible to downsize the entire device and reducing the amount of exhaust gases that cause pollution. However, SandTrak■, which is said to have the highest performance as a commercially available traction fluid, does not provide satisfactory performance in terms of traction coefficient when used in such Traxijin drive devices, and is also expensive. There's a problem. Furthermore, the traction fluid proposed in Japanese Patent Publication No. 48-35783 also has problems in terms of performance and price since it contains Sandtrack (2) or a similar substance as one of its components.

(Means for Solving the Problems) As a result of extensive research in order to obtain a traction fluid that has a high traction coefficient and is relatively inexpensive, the present inventors have discovered a diester or a diester having two cyclohexyl rings. The present invention was completed by confirming that it is possible to economically provide a base oil fluid with high performance by blending a specific amount of branched polyalphaolefin with the derivative.

[In the formula, A' is an ester bond of -COO- or 10OC-, n is 1 to 6, and R1 is a hydrogen atom, with a carbon number of 1
-8 alkyl groups, and R2 is one or two selected from alkyl groups having 1 to 3 carbon atoms. This invention relates to a traction fluid characterized by containing 0.1 to 70% by weight of alpha olefin.

A first object of the present invention is to provide a high performance traction fluid with a high traction coefficient. A second object of the present invention is to provide a traction fluid that is economical, easy to handle, and easy to apply to devices.

The traction fluid of the present invention is composed of a two-component base oil, in which a diester or its derivative as the A component is blended with a specific amount of a branched polyalphaolefin as the B component.

Component A of the present invention is a diester having two cyclohexyl rings or a derivative thereof, and has the above structural formula. A' of the ester bond is -COO- or -0
00-, and n of the repeating unit of the gem-dialkyl structure is 1 to 6, particularly preferably 1 to 3. When n is 0, the traction coefficient is low, and when n is 7 or more, the viscosity becomes high, which is not preferable. This diester or its derivative is
It is manufactured by the method described below and has the following properties.

Viscosity is 20-50 cst at 40°C, especially 24-30
cst is preferred, 4 to to cst, especially 4 to 6 cst at 100°C. In addition, the viscosity index is 40~
100. Particularly preferred is a range of 50 to 80.

Component A can be produced by the method shown below.

Component A can be obtained by an esterification reaction between a glycol compound and a cyclohexanecarboxylic acid compound. As the glycol compound, one having 1 to 6 gel-dialkyl structures is selected, and neopentyl glycol is preferred. In addition to cyclohexanecarboxylic acid, the cyclohexanecarboxylic acid compound has 1 to 8 carbon atoms.
Examples of those having an alkyl group include methylcyclohexanecarboxylic acid and ethylcyclohexanecarboxylic acid. Particularly preferred is cyclohexanecarboxylic acid. The esterification reaction can be carried out around the equivalent of the Habo reaction or under acidic excess conditions, but the former requires a catalyst and has problems such as the production of monoalcohol by-products, so it is better to use acidic conditions. preferable. That is, the acid is reacted in an amount of 2 to 5 times the mole (particularly preferably 2.5 to 4 times the mole) per mole of the glycol compound. The reaction temperature is about 150-250°C, preferably 170-230°C, and the reaction time is 10-40 hours, preferably 15-25 hours.
Time. The reaction pressure may be increased or reduced pressure, but normal pressure is preferred from the viewpoint of reaction operation. Under this condition, excess acid acts as a catalyst. Further, an appropriate amount of alkylbenzene such as xylene or toluene can be added as a solvent. By adding a solvent, the reaction and temperature can be easily controlled. As the reaction progresses, the water produced evaporates, and the reaction is terminated when the amount of water becomes twice the mole of alcohol. Excess acid is neutralized with an aqueous alkaline solution and removed by washing with water. If the acid is difficult to remove by alkaline washing, the acid is made 2 to 265 times the mole of the alcohol and reacted using a catalyst. As the catalyst, phosphoric acid, para-toluenesulfonic acid, sulfuric acid, etc. can be used, but it is most preferable to use phosphoric acid in terms of increasing the reaction rate and increasing the yield of ester. The diester compound of the present invention is
Finally, the reaction product is distilled under reduced pressure to remove water and solvent. Component A of the present invention can also be produced by esterifying a cyclohexanol compound and a dicarboxylic acid having a quaternary carbon. In this case, the cyclohexanol compound may be cyclohexanol or methylcyclohexanol, and the dicarboxylic acid may be neopentyldicarboxylic acid or the like.

The polyalphaolefin as component B has a quaternary carbon atom or a tertiary carbon atom in the main chain, and has a carbon number of 3.
-5 alpha olefin polymers and hydrogenated products thereof. Examples include polypropylene, polybutene, polyisobutylene, polybentene, and hydrogenated products thereof, and particularly preferred are polybutene, polyisobutylene, and hydrogenated products thereof. Polyisobutylene can be represented by the following structural formula.

Moreover, the hydrogenated product is shown by the following structural formula.

However, the above degree of polymerization n is 6 to 200.

Polybutene and polyisobutylene may be commercially available products, but they can be produced by polymerization using known methods. Further, the hydrogenated product is produced by reacting polyisobutylene or the like in the presence of hydrogen. Particularly preferred polyalphaolefins have molecular weights in the range of 500 to 10,000, more preferably 900 to 5.000. The molecular weight may be adjusted by decomposing a high molecular weight polyalphaolefin, mixing a low molecular weight polyalphaolefin, or the like. Incidentally, an alpha olefin copolymer (QCP) is a polymer whose manufacturing raw materials are partially the same as polyalpha olefin, but this OCP is not suitable for use as component B in the present invention. This is because OCP is obtained by polymerizing two or more alpha olefins and has a structure in which they are irregularly connected, and is not a regular gem-dimethyl type structure like the polybutene of the present invention.

In the present invention, component A, such as neopentyl glycol cyclohexane carboxylic acid diester, exhibits a traction coefficient of 0.100 to 0.104, and component B, such as polybutene, exhibits a traction coefficient of 0.075 to 0.0.
This shows a value of 85.

Since component A of the present invention has a high traction coefficient, even if component A is applied alone to a traction drive device, high performance can be achieved. However, by blending 0.1 to 70% by weight of polyalphaolefin as component B with component A, a more preferable traction fluid can be obtained. That is, although component B has a lower traction coefficient than component A, the gem-dimethyl group of component B exerts a synergistic effect with the cyclohexyl ring of component A to improve the traction coefficient, and it is also inexpensive and has excellent viscosity characteristics. Therefore, the B component is 0.
By blending 1 to 70% by weight, it is possible to economically obtain a traction fluid without lowering the traction coefficient.

The traction fluid of the present invention may also contain various additives depending on the intended use. In other words, if the traction device is subject to high temperatures and heavy loads, antioxidants,
Approximately 0.01 to 5% by weight of one or more types of additives such as anti-wear agents or anti-rust agents can be blended.

Similarly, when a high viscosity index is required, 1 to 10% by weight of a known viscosity index improver may be added. However, if polymethacrylate or olefin copolymer is used, the traction coefficient will decrease, so the amount of these added should be 4.
Must be less than % by weight.

In the present invention, the traction fluid refers to a fluid used in a device that transmits rotational torque through point contact or line contact, or a transmission device having a similar structure. The traction fluid of the present invention has a higher traction coefficient than conventionally known fluids, and has a traction coefficient 1 to 5% higher than conventional products, depending on properties such as viscosity. Therefore, the traction fluid of the present invention is suitable for use in internal combustion engines such as small passenger cars, relatively low-power transmission devices such as spinning machines and food manufacturing machines, as well as traction drive devices of large-power industrial machines. Can be applied.

(Function) Although the traction fluid of the present invention has a much superior traction coefficient compared to known fluids, it is still not completely clear why it exhibits such a high traction coefficient. It has not been. Basically, it is thought that this is based on the unique molecular structure of the traction fluid of the present invention.

First, the traction fluid of the present invention is a diester and has two cyclohexyl rings in the compound molecule.
Because they are ester-bonded, dipole opening force acts between the molecules. It is believed that this dipole opening force changes the fluid into a stable glass state under high load conditions of the traction device, increasing the anti-shear force. Furthermore, the traction fluid of the present invention has a g8111-dialkyl type quaternary carbon in both the A component and the B component, and the A component is bonded to two cyclohexyl rings via a methoxycarbonyl bond, so that it is in the molecule. It has a structure that makes it difficult to rotate. Therefore, it is thought that when the traction device is under high load, the cyclohexyl ring and the gem-dialkyl part of the quaternary carbon are tightly engaged like gears, and when the load is released, they quickly separate and become fluidized.

(Example) Examples 1 to 11 Neopentyl glycol cyclohexane carboxylic acid diester of the present invention was synthesized by the following method.

One mole of neopentyl glycol was mixed with three times the mole of cyclohexanecarboxylic acid, and the reaction temperature was 200°C and 20% at normal pressure.
Allow time to react. Due to the excessive acid conditions, no catalyst was used.
Xylene is used as a solvent. The reaction is terminated when the amount of water that evaporates during the reaction reaches twice the mole of alcohol. Wash away excess acid with alkali (caustic soda) and rinse with water until neutral. The diester of the present invention is isolated by distilling the reaction product under reduced pressure to remove water and xylene.

Next, the diester thus produced had an average molecular weight of 420.
-2350 polybutene was blended and the traction coefficient was determined. The conditions for measuring the traction coefficient are as follows.

Measuring device Nisota type 40-L traction tester Test conditions: Water temperature 20°C, roller temperature 30°C, average Hertzian pressure 1.2 GPa.

Rolling speed 3.6m/s.

Slip rate: 3.0% As shown in Table 1, the traction fluid of the present invention was found to have significantly superior traction performance compared to conventional traction fluids.

Comparative Examples 1 to 7 Traction was carried out under the conditions shown in the examples using a traction fluid containing 100% by weight of component B and 90% by weight of component B, a traction fluid containing OCP or PMA as component A, and a commercially available traction fluid. The coefficient was measured.

As a result, as shown in Table 1, all of the traction fluids have a traction coefficient of 1 to 1b higher than the traction fluid of the present invention. PMA was polymethacrylate, specifically a polymer having an average molecular weight of 50,000 to 300,000.

(Effects of the Invention) The present invention is a traction fluid in which component A, such as a diester having two cyclohexyl rings, is blended with a specific amount of component B, which is a branched polyalphaolefin, and not only has an extremely high traction coefficient. It is inexpensive and has excellent viscosity characteristics.

Therefore, when used in a power transmission device, particularly a traction drive device, the shearing force under high loads can be dramatically increased, so the device can be miniaturized and an economical device can be provided.

Claims (1)

[Claims] 1) General formula ▲ Numerical formula, chemical formula, table, etc. ▼ [In the formula, A' is an ester bond of -COO- or -OOC-, n is 1 to 6, R_1 is a hydrogen atom, Carbon number 1-8
and R_2 is one or two selected from alkyl groups having 1 to 3 carbon atoms. -Olefin from 0.1 to 7
A traction fluid characterized by containing 0% by weight. 2) The fluid according to claim 1, wherein the polyalpha-olefin is polybutene. 3) The fluid according to claim 1, wherein the amount of polyalpha-olefin is 10 to 50% by weight. 4) R_1 of the diester compound is a hydrogen atom and has 1 carbon number
The fluid according to claim 1, wherein the fluid is one or two selected from the group consisting of -4 alkyl groups. 5) The average molecular weight of the polyalpha-olefin is 500
10,000 to 10,000. 6) The fluid according to claim 1, wherein n of the diester compound is 1 to 3. 7) The fluid according to claim 1, wherein R_2 of the diester is a methyl group.