JPH0588760B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a traction fluid, and more specifically, a traction fluid containing a diester having two cyclohexyl rings or a derivative thereof and a branched polybutene as a base oil. It is related to. (Prior Art) In automobiles and industrial machines, traction drive power transmission devices that transmit power to driven parts through traction drive mechanisms have attracted attention, and research and development have been actively promoted in recent years. A traction drive mechanism is a power transmission mechanism that uses rolling friction, etc., and because it does not use gears like traditional gears, vibration and noise are reduced, and high-speed speed changes can be performed very smoothly. Improving the fuel efficiency of cars has become 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 maximum fuel efficiency range, making it possible to improve the fuel efficiency of conventional transmissions. It is said that this system can reduce fuel consumption by more than 20% compared to the conventional system. Recent research results include the development of materials with high fatigue strength and theoretical analysis of traction mechanisms, and the correlation of traction coefficients at the molecular structure level of components of traction fluids is gradually being clarified. be. Here, the traction coefficient is defined as the ratio of the traction force generated by sliding of the contact portions of rotating bodies that contact each other in a rolling friction power transmission device to the normal load. The traction fluid must be a lubricating oil with a high traction coefficient, and it has been confirmed that the molecular structure of the fluid has a naphthene ring to exhibit high performance. is widely known.
As a traction fluid having a naphthene ring, Japanese Patent Publication No. 47-35763 discloses di(cyclohexyl)alkane or dicyclohexane. This patent states that a fluid containing a perhydrogenated (alpha-methyl)styrene polymer, a hydrindane compound, or the like mixed with the alkane compound has a high traction coefficient. Further, JP-A No. 59-191797 discloses a traction fluid containing an ester compound having a naphthene ring, in which aromatic nuclear hydrogen of cyclohexyldicarboxylic acid dicyclohexyl ester or phthalic acid cydiclohexyl ester is disclosed. It is said that the ester obtained by addition is preferable as a traction fluid. (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. Since the permissible transmission force can be increased, the entire device can be downsized, and the amount of exhaust gases that cause pollution can be reduced, and there is a strong desire for a fluid with as high a traction coefficient as possible. However, even commercially available traction fluids that are currently considered to have the highest performance do not provide satisfactory performance in terms of traction coefficient when used in such traction drive devices, and are expensive. There is a problem.
Furthermore, the traction fluid proposed in Japanese Patent Publication No. 46-35763 also has problems in terms of performance and price since it contains Santotrac or a similar substance as one of its components. (Means for Solving the Problems) The present inventors have conducted extensive research to obtain a traction fluid that has a high traction coefficient and is relatively inexpensive. 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 polybutene with a diester or its derivative linked via a polybutene. The present invention is based on the general formula

[Formula] [In the formula, A' is an ester bond of -COO- or -OOC-, n is 1 to 10, and R ₁ is the same or different and selected from a hydrogen atom and an alkyl group having 1 to 8 carbon atoms. _R2 is the same or different atoms or groups selected from a hydrogen atom and an alkyl group having 1 to 3 carbon atoms. Polybutene with a molecular weight of 500 to 10,000 from 0.1 to 95
This relates to a traction fluid characterized in that it contains % by weight. A first object of the present invention is to provide a traction fluid with excellent performance and a high traction coefficient. A second object of the present invention is to provide a traction fluid that is economical, readily available, and easily applicable to equipment. The traction fluid of the present invention is composed of a two-component base oil, in which diester or its derivative as the A component is blended with a specific amount of branched polybutene 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 -OOC-, and the number n of carbon atoms in the chain hydrocarbon skeleton is 1 to 10, particularly preferably 1 to 4. When n is 0, the traction coefficient is low, and when n is 11
If it is more than that, the viscosity becomes high, which is not preferable. This diester or its derivative is produced by the method below and has a viscosity of 5 to 50 cst at 40°C, particularly preferably 7 to 30 cst, and 1 to 10 cst, particularly preferably 2 to 6 cst at 100°C. It is. Furthermore, examples of diester derivatives include amino compounds and ether compounds. Component A can be produced by any of the following methods. The first method is a method using an esterification reaction between a dihydric alcohol compound and a cyclohexanecarboxylic acid compound. As the dihydric alcohol compound, one having a main chain carbon number of 1 to 10 is selected, and a dihydric alcohol having a carbon number of 1 to 4 is particularly preferred. Specific examples include ethylene glycol, 1-3-propanediol, 1-3-butanediol, and 1-4-butanediol. In addition to cyclohexanecarboxylic acid, cyclohexanecarboxylic acid compounds include
It has 8 to 8 alkyl groups, such as methylcyclohexanecarboxylic acid or ethylcyclohexanecarboxylic acid. Particularly preferred is cyclohexanecarboxylic acid. The esterification reaction is carried out either at a molar ratio of alcohol and acid of 1:2 or under acidic conditions; however, in the former case, a catalyst is required and there are problems such as production of monoalcohol by-products, so acidic conditions are not recommended. It is preferable to adopt it. That is, the amount of acid is 2 to 5 times the mole (particularly preferably 2.5 times) per mole of the dihydric alcohol compound.
~4 times the mole). Reaction temperature is 150-250
℃, preferably 170-230℃, reaction time 10-230℃
40 hours, preferably 15-25 hours. 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 produced water evaporates, and the reaction is terminated when the amount of water becomes twice the mole of alcohol. Excess acid is neutralized with an aqueous alkali solution and removed by washing with water. When using an acid that is difficult to remove by alkaline washing, the acid is 2 to 2.5 times the mole of the alcohol and the reaction is carried out using a catalyst. As the catalyst, phosphoric acid, p-toluenesulfonic acid, sulfuric acid, etc. can be used, but phosphoric acid is most preferably used from the viewpoint of increasing the reaction rate and the yield of ester. The diester compound of the present invention is obtained by finally distilling the reaction product under reduced pressure to remove water and the solvent. A second method for producing component A of the present invention is a method by esterifying a cyclohexanol compound and a dicarboxylic acid having a main chain of 3 to 12 carbon atoms. In addition to cyclohexanol, the cyclohexanol compound has an alkyl group having 1 to 8 carbon atoms, such as methylcyclohexanol, tert-butylcyclohexanol, and the like. Particularly preferred is cyclohexynol. The dicarboxylic acid has a main chain of 3 to 12 carbon atoms, preferably a main chain of 3 to 6 carbon atoms.
carbon atoms. Examples include malonic acid, succinic acid, glutaric acid, and the like.
The esterification reaction is carried out in a molar ratio of alcohol and acid of 2:1 or in an excess of alcohol, but in the former case, excess alcohol is preferred since monocarboxylic acid by-products may be produced. That is, the cyclohexanol compound is reacted with 2.5 to 5 times the molar amount of the dicarboxylic acid. The reaction temperature is 150-250°C, preferably 170-230°C, and the reaction time is 10-40 hours, preferably 15-25 hours. The reaction pressure may be increased or reduced pressure, but normal pressure is preferred from the viewpoint of reaction operation. Further, an appropriate amount of alkylbenzene such as xylene or toluene can be added as a solvent. By adding a solvent, the reaction temperature can be easily controlled. As the reaction progresses, the water produced evaporates, and the reaction is terminated when the amount of water reaches twice the mole of the dicarboxylic acid. Phosphoric acid, para-toluenesulfonic acid, sulfuric acid, etc. are used as a catalyst. Phosphoric acid is most preferably used since it increases the reaction rate and yield of ester. The diester compound of the present invention is obtained by finally distilling the reaction product under reduced pressure to remove water, solvent, and excess alcohol. Polybutene as component B has quaternary carbon atoms or tertiary carbon atoms in the main chain, and has 3 carbon atoms.
-5 alpha olefin polymers and hydrogenated products thereof. Preferred are polybutene (including polyisobutylene) and hydrogenated products thereof. Polyisobutylene can be represented by the following structural formula.

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

[Chemical formula] However, the above degree of polymerization n is 6 to 200. Commercially available products may be used for polybutene and polyisobutylene, but they can also be produced by known polymerization methods. Further, the hydrogenated product is produced by reacting polyisobutylene or the like in the presence of hydrogen. Particularly preferred polybutenes are those with a molecular weight in the range of 500 to 10,000, more preferably those in the molecular weight range of 900 to 5,000. The molecular weight may be adjusted by decomposing a high molecular weight polybutene, mixing polybutenes having different molecular weights, or the like. Although alpha olefin copolymer (OCP) is a type of polyalpha olefin, this OCP is not suitable for use as component B of the present invention. The reason for this is that OCP is obtained by polymerizing two or more alpha olefins and has a structure in which they are irregularly connected.
This is because it does not have a gem-dialkyl type structure. In the present invention, component A, such as a diester of succinic acid and cyclohexanol, exhibits a traction coefficient of 0.120 to 0.106, and component B, such as polybutene, exhibits a traction coefficient of 0.075 to 0.085. Since the A component of the present invention has a high traction coefficient, even if the A component is applied alone to a traction drive device, high performance can be achieved. However, 0.1% polybutene of component B is added to component A.
A more preferable traction fluid can be obtained by blending up to 95% by weight, especially 10 to 70% by weight. That is, although component B has a lower traction coefficient than component A, the gem-dialkyl group of component B exerts a synergistic effect (effect of improving the traction coefficient) with the cyclohexyl ring of component A. In addition, component B is inexpensive and has excellent viscosity characteristics, so by blending it in an amount of 0.1 to 95% by weight with respect to component A, it is possible to economically obtain a traction fluid without lowering the traction coefficient. The traction fluid of the present invention can also contain various additives depending on the intended use. In other words, if the traction device is subject to high temperatures and heavy loads, one or more additives such as antioxidants, anti-wear agents, or anti-corrosion agents should be added in an amount of 0.01 to 100%.
It can be blended in an amount of about 5% by weight. Similarly, if 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 be lowered, so it is desirable that the amount of these added be 4% by weight or less. In the present invention, the traction fluid is
A fluid used in a device that transmits rotational torque through point contact or line contact, or in a transmission device with a similar structure. The traction fluid of the present invention has a higher traction coefficient than conventionally known fluids,
It has a traction coefficient that is 5 to 15% higher than conventional products, depending on the columnar shape such as viscosity. Therefore, the traction fluid of the present invention can be used not only in internal combustion engines such as small passenger cars, but also in relatively low-power transmission devices such as spinning machines and food manufacturing machines, as well as in traction drives of large-power industrial machines. It can also be preferably applied to devices. (Function) The traction fluid of the present invention has a much superior traction coefficient compared to known fluids, but it is still not completely clear why it exhibits such a high traction coefficient. It has not been. Basically, this is thought to be based on the unique molecular structure of the traction fluid of the present invention. First, component A of the traction fluid of the present invention is a diester having two cyclohexyl rings in the compound molecule, and due to the two ester bonds, dipoles act between the molecules. It is believed that this dipole-dipole force changes the fluid into a stable glass state under high load conditions of the traction device, increasing the shear resistance. Furthermore, the B component of the traction fluid of the present invention has a gem-dialkyl type quaternary carbon. Therefore, when the traction device is under high load, the cyclohexyl ring of component A and the gem-dialkyl moiety of the quaternary carbon of component B are tightly engaged like gears, and when the load is released, they quickly separate and become fluidized. considered to be a thing. (Example) Examples 1 to 13 Diester _A1 of the present invention was synthesized by the following method. First, add 250g of cyclohexynol to the reaction vessel.
and 104 g of malonic acid (0.4 mol per 1 mol of cyclohexanol) were collected, and 1% by weight of phosphoric acid was added to the total amount. Next, heat the reaction vessel to 180℃,
The reaction was carried out at a temperature range of 180-210°C under normal pressure. The water produced as the reaction progresses is removed from the mixture of the reaction product cyclohexanol and malonic acid diester, the unreacted cyclohexanol and phosphoric acid, and vacuum distillation is performed after alkali washing to remove unreacted substances. , pure diester A ₁ was isolated. Similarly, the diester of the present invention was prepared using the following raw materials.
A ₂ and A ₃ were synthesized. A ₂ ... Ethylene glycol and cyclohexanecarboxylic acid (excess acid) A ₃ ... Succinic acid and cyclohexanol Next, polybutene having an average molecular weight of 900 to 2350 was blended with the diester thus produced, and the traction coefficient was measured. The conditions for measuring the traction coefficient are as follows. Measuring device: Soda type 4-roller traction tester Test conditions: Oil temperature 20°C, roller temperature 30°C, average Hertzian pressure 1.2GPa, rolling speed 3.6m/s, slip rate 3.0% The traction fluid of the present invention is the first As shown in the table, it was found that this fluid has significantly superior traction performance compared to conventional traction fluids. Comparative Examples 1 to 9 B component 100% by weight, A ₁ to A ₃ components OCP or
Using a traction fluid containing 5 to 30% by weight of PMA and a commercially available traction fluid (Santo Truck), the traction coefficient was measured under the conditions shown in the examples. As shown in Table 1, it was found that the traction coefficients of all the fluids were 5 to 15% smaller than that of the traction fluid of the present invention. In addition, OCP
is an olefin copolymer, specifically a polymer of ethylene and propylene (average molecular weight 150,000 to 300,000)
PMA was polymethacrylate, specifically a polymer having an average molecular weight of 50,000 to 300,000.

【table】

[Table] (Effects of the Invention) The present invention is a traction fluid in which a specific amount of branched polybutene component B is blended into component A, such as a diester having two cyclohexyl rings and a chain hydrocarbon skeleton. Not only does it have an extremely high traction coefficient, it is also 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 that the device can be miniaturized and economically supplied.

Claims (1)

[Claims] 1 General formula [Formula] [In the formula, A' is an ester bond of -COO- or -OOC-, n is 1 to 10, and R ₁ is the same or different and is a hydrogen atom and a carbon number of 1 -1 or 2 selected from 8 alkyl groups, R ₂ is the same or different atom or group selected from a hydrogen atom and an alkyl group having 1 to 3 carbon atoms] or a derivative thereof A traction fluid characterized by containing 10 to 70% by weight of branched polybutene having an average molecular weight of 500 to 10,000. 2. The traction fluid according to claim 1, wherein R ₁ of the diester is the same or different and is one or two selected from a hydrogen atom and an alkyl group having 1 to 4 carbon atoms. 3. The traction fluid according to claim 1, wherein R ₂ of the diester is either a hydrogen atom or a methyl group.