JPS6261637B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a lubricating oil for a power transmission device, and particularly to a lubricating oil for a power transmission device suitable for use in a traction drive. Gears and hydraulic devices have traditionally been used to transmit power and change speeds, but a drive system called traction drive (rolling friction drive device) that uses point or line contact between rotating rigid bodies is also known. It is beginning to be put into practical use in some industrial machinery because it has no vibrations during operation, and has high power transmission efficiency. In this case, the most suitable lubricating oil must be selected from the functional point of view as the oil present in the contact area.
In other words, the oil present in the contact area undergoes a reversible glass transition under high pressure and increases in viscosity, which has a large power transmission effect on the rotating contact surface, and has the property of returning to a fluid state immediately after leaving the contact surface. , and prevents direct contact between metals, preventing seizure wear,
It must prevent fatigue damage and also have important functions such as rust prevention and cooling similar to general lubricating oils. The present invention relates to a lubricating oil for such power transmission devices, and particularly to a lubricating oil suitable for use in traction drives. Friction or traction drive devices for power transmission have been described in many prior technical documents;
For example, US Patent No. 3394603, US Patent No. 3411369
No., Journal of Chemical and Engineering Data, Vol. 5, No. 4, pp. 499-507,
Proceedings of a symposium on rolling contact phenomena by Huyuko et al., pp. 157-185, Nilsevier Publishers (Amsterdam), 1962. Lubricating oils for traction drives include mineral oil (Japanese Patent Publication No. 39-24635), polymethyl methacrylate (Japanese Patent Publication No. 48-31828), pivalic acid monoester (Japanese Patent Publication No. 49-11309), and halogenated alkylnaphthalene (Japanese Patent Publication No. 49-11309). Publication No. 49-16900), adamantane (Japanese Patent Publication No. 48-42067, 48-42068), polyolefins (Japanese Patent Publication No. 4766-1976, 47-2229)
), alkylnaphthalene (U.S. Patent No.
2549377), but there are also many proposals regarding naphthenic oils having hydrogenated rings. The proposed naphthenic oils include dicyclohexylethane (Japanese Patent Publication No. 48-29715), dicyclohexylpropane (Japanese Patent Publication No. 53-36105), hydrogenated condensed ring compounds (US Patent No. 3411369), and one or more saturated carbon rings. naphthenes (U.S. patent no.
3440894), naphthene having two or more saturated carbon rings (US Patent No. 3925217), and mixed oils of naphthenes and paraffins (US Patent Nos. 3595796 and 3595797). Also, those obtained by hydrogenating alkylation reaction products of xylene and/or toluene and styrene (mainly hydrogenation 1,
1-diallylethane type compounds) and the like are also known. U.S. Pat. No. 3,440,894 and U.S. Pat.
The technology described in each specification of No. 3925217 includes a wide range of naphthenic compounds and exemplifies a large number of naphthenes, many of which are compounds with hydrogenated rings. Furthermore, many of those with excellent traction properties have a relatively high viscosity of 20 cst or more at 40°C. On the other hand, in actual use, the efficiency of the traction drive decreases due to viscous resistance in the operating parts other than the rolling surface, and it is also used in the traction drive to improve the cooling performance of the rolling surface. It is desirable that the lubricating oil be as low in viscosity as possible. Therefore, the object of the present invention is to not only satisfy the viscous resistance and cooling properties and have excellent traction properties, but also to have excellent performance in terms of oxidation stability, corrosion resistance, etc. From an industrial standpoint, the object of the present invention is to provide a lubricating oil for power transmission devices that can use extremely inexpensive raw materials. The present inventors have discovered that a specific alkylbenzene is specifically effective for the purpose of the present invention due to its molecular structure, and has accomplished the present invention. The lubricating oil for power transmission devices according to the present invention has a boiling point range (converted to normal pressure) obtained by reacting a propylene polymer with benzene, toluene, or xylene.
It is a lubricating oil whose main component is alkylbenzene with a temperature of 250 to 450℃. Here, the boiling point range (converted to normal pressure) is
If the temperature is less than 250°C, there will be problems with the flammability of the lubricating oil according to the present invention, and if it exceeds 450°C, there will be problems with its viscosity characteristics and cooling performance. are excluded. Typical specific examples of the alkylbenzenes of the present invention include isononylbenzene in which the alkyl group component is of the propylene trimer type, isododecylbenzene of the propylene tetramer type, isopentadecylbenzene of the propylene pentamer type, and by-produced during their production. Heavy alkylbenzenes, etc. Among these, propylene tetramer type isododecylbenzene is particularly desirable in the present invention. However, the propylene trimer here is obtained when so-called propylene trimer is produced industrially, and has a carbon atom number range of 7 to 11, with _C9 as the main component. Similarly, propylene tetramer has a carbon atom number range of 10 to 15, and propylene pentamer has a carbon atom number range of 13 to 18. These alkylbenzenes of the present invention can be produced using, for example, propylene at a temperature of 100 to 300°C using a phosphoric acid catalyst.
Propylene trimer (trimer), propylene tetramer (tetramer), propylene pentamer (pentamer) or a mixture thereof polymerized at a pressure of 10 to 60 Kg/cm ² is treated with hydrogen fluoride, sulfuric acid, aluminum chloride, etc. It is obtained by reacting with benzene, toluene, or xylene using a Friedel-Crafts type catalyst. When aluminum chloride is used as a catalyst, the reaction temperature can range from 20 to 150°C, but is preferably from 40 to 80°C. Moreover, the reaction pressure is advantageously 1 to 10 kg/cm ² G. Note that heavy alkylbenzene is obtained as a by-product during alkylation. Although benzene, toluene, or xylene used in the present invention is extremely easily available and inexpensive, it is desirable to use benzene from the viewpoint of yield. The lubricating oil for power transmission devices according to the present invention may contain a small amount of mineral oil, other naphthenic oil, etc., and the lubricating oil according to the present invention has oxidation stability, thermal stability, corrosion resistance, and rust prevention properties. , shear stability,
Although it has sufficient performance in terms of wear resistance, etc., additives such as antioxidants, corrosion inhibitors, rust preventives, antifoaming agents, etc. can be contained in order to improve these performances. Further, there is no problem in the presence of a small amount of by-products generated during the process of producing the alkylbenzene of the present invention. The traction coefficient is generally measured using a traction drive device, but in the present invention, a Soda type cylindrical friction tester was used. Traction (rolling friction) occurs at three contact points between the central cylinder and three cylinders placed outside, and the same vertical load acts on the contact points. The surface pressure at this time is 0.575 to 1.157 GPa in terms of average Hertzian pressure. Other conditions are as shown in Table 1 below.

[Table] The operating procedure for the experiment is to first adjust the rotation speed to
After applying a load while keeping the outer cylinder constant, the slip rate was increased by increasing only the rotational speed of the outer cylinder, and changes in friction torque or traction coefficient relative to the slip rate were continuously determined. Friction torque was measured by directly measuring the torsional moment of the central free support shaft using a resistance wire strain gauge. The traction coefficient measured under these conditions shows a tendency to first rise linearly as the slip rate increases, then reach a maximum and then decline.
In this case, the particularly important region from a practical standpoint is the initial linear region where the heat generated by shearing the oil film is not large, and the traction coefficient in this region will be of particular interest below. As an example, the traction coefficient measured at an average Hertz pressure of 1.157 GPa, a rotational speed of 4.19 m/S, and a sliding speed of 0.022 m/S is shown in Table 2 below, and the lubricating oil according to the present invention has a traction coefficient of 0.07.
From the above, it has become clear that it is superior to these hydrocarbons.

[Table] In addition to the above-mentioned traction properties, the performance required for lubricating oils for traction drives includes oxidation stability, viscosity index, and viscosity index required for general lubricating oils.
Corrosion resistance, wear resistance, rust prevention, rubber lubricity,
Examples include anti-foaming properties, and it is necessary to mix appropriate additives depending on each application.
Here, these additives,
For example, as antioxidants, alkylphenols such as 2,6-ditertiarybutyl para-cresol, zinc dialkyldithiophosphate, etc.
Phosphorus compounds are used as rust preventive agents such as amines, esters,
It is possible to add one or more metal salts, polymethacrylates as a viscosity index improver, and silicone polymers as an antifoaming agent. The present invention will be illustrated below with reference to Examples, but the embodiments of the present invention are not limited thereto. Example Propylene was heated to 190°C using a solid phosphoric acid catalyst.
Polymerize under the conditions of ℃ and 35 kg/cm ² pressure to form propylene tetramer (tetramer). Since this propylene tetramer contains by-product polymers, a fraction with a boiling point range of 170 to 230°C was collected by distillation. The typical composition of this propylene tetramer is, for example:
Analytical chemistry Vol.35, 12 (1963) 2219
According to an analytical method based on
%, monosubstituted product remained. Next, propylene tetramer having the above boiling point range was mixed with aluminum chloride in 1 part of benzene using aluminum chloride as a catalyst.
0.01 part was added, heated to 70°C, reacted with benzene, and subjected to so-called alkylation to obtain dodecylbenzene. This dodecylbenzene contains by-product alkylbenzene, so it is distilled to reduce the boiling point range.
A fraction between 170 and 185°C (pressure: 13 mmHg) was collected.
The traction coefficient of the above dodecylbenzene is 0.07
The general properties were as shown in Table 3 below.

[Table] To the above dodecylbenzene, 0.5wt% each of phenolic and zinc antioxidants were added and the oxidation test was carried out in JIS-K-2514-1980 (Lubricating oil oxidation stability test method) Section 3.2 (Internal combustion engine lubrication The test was carried out according to the basic procedure described in the Oil Oxidation Stability Test Method. The results are shown in Tables 5, 6 and 7 below. Tables 5 to 7 below compare the oxidation test results of the following commercially available naphthenic mineral oils and the lubricating oil according to the present invention.

【table】 The test conditions are shown in Table 4 below.

【table】

【table】

【table】

[Table] As is clear from the results shown in Tables 5 to 7 above, it can be seen that the lubricating oil according to the present invention has extremely excellent stability.

Claims (1)

[Scope of Claims] 1. A lubricating oil for a power transmission device comprising an alkylbenzene having a boiling point range (converted to normal pressure) of 250 to 450°C obtained by the reaction of a propylene polymer and benzene, toluene, or xylene. 2. The lubricating oil for a power transmission device according to claim 1, wherein the power transmission device is a traction drive.