JP2015105289A - Industrial gear oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the frictional coefficient of an industrial gear oil composition and maintain its abrasion resistance.SOLUTION: A mineral oil and/or paraffin synthetic oil of a lubrication base oil contains an organomolybdenum compound and dithiocarbamate compound as a friction modifier.

Description

  TECHNICAL FIELD The present invention relates to an industrial gear oil composition, and relates to an industrial gear oil composition that can be suitably used for a gear device used in industrial machinery and the like.

  In recent years, industrial gear oils are required to save energy in industrial machines and to extend the oil replacement life.

Energy saving is required to reduce the friction coefficient of gear oil for the purpose of suppressing CO ₂ generation and reducing power costs. On the other hand, as an industrial gear oil, there is a demand for extending the oil replacement life for the purpose of reducing maintenance work associated with a decrease in maintenance personnel or reducing maintenance costs.

  As industrial gear oil, those with reduced friction coefficient are being sold as energy-saving types such as industrial machines, but further reduction of the friction coefficient is required.

  As a method for reducing the friction coefficient, there is generally a method of adding an organomolybdenum compound to industrial gear oil. Moreover, as a method of ensuring extreme pressure properties, a method of adding a sulfur-phosphorus extreme pressure agent together with an organic molybdenum compound (for example, see Patent Documents 1 and 2) or a method of adding an alkali metal borate hydrate. (For example, refer to Patent Document 3).

  However, in these methods, the effect of organic molybdenum, that is, the effect of reducing the friction coefficient cannot be sufficiently obtained.

  On the other hand, in order to extend the oil replacement life, it is necessary to suppress the oxidative deterioration of the oil and to maintain the wear resistance during long-term use.

  As gear oils that suppress oxidative degradation of oils, those based on synthetic oils such as poly-α-olefins are commercially available.

  However, such gear oil has a problem that the coefficient of friction is high and an energy saving effect cannot be obtained sufficiently. Further, when the coefficient of friction is high, there is a problem that the wear resistance due to long-term use decreases because the viscosity decreases due to an increase in the oil temperature and the deterioration of additive components is accelerated.

  Further, when the energy saving type gear oil is used for a long period of time, the wear resistance is reduced due to the consumption and deterioration of the additive. Such gear oil has a problem in that wear resistance increases, wear powder increases, and a gear oil replacement cycle is shortened.

  Therefore, it is desired that industrial gear oil is excellent in the effect of reducing the friction coefficient and can maintain the wear resistance even after long-term use.

JP 2010-95691 A JP 2011-6635 A JP-A-6-220475

  Therefore, the present invention has been proposed in view of such circumstances, and provides an industrial gear oil composition that is excellent in reducing the friction coefficient and can maintain wear resistance even when used for a long period of time. With the goal.

  The industrial gear oil composition according to the present invention that achieves the above-mentioned object is characterized by containing a lubricating base oil and an organic molybdenum compound and a dithiocarbamate compound as a friction modifier.

  In the present invention, since the dithiocarbamate compound is contained together with the organic molybdenum, the friction coefficient is excellent, and the wear resistance can be maintained even when used for a long time.

It is a figure which shows the measurement result of the friction coefficient by the SRV test of an Example and a comparative example. It is a figure which shows the result of abrasion resistance evaluation by LFW-1 of an Example and a comparative example.

  Below, the industrial gear oil composition to which this invention is applied is demonstrated in detail. Note that the present invention is not limited to the following detailed description unless otherwise specified.

  Industrial gear oil compositions are used in gear devices for gearboxes and speed reducers for industrial machines, for example, to reduce the friction coefficient of the gear device and maintain a low friction coefficient, thereby realizing energy saving of the gear device. Can do. In addition, the industrial gear oil composition can maintain wear resistance even when used for a long period of time, extend its life, and can be used for a long period of time.

  Such an industrial gear oil composition (hereinafter simply referred to as a gear oil composition) includes a mineral oil and / or a paraffinic synthetic oil as a lubricating base oil, an organic molybdenum compound as a friction modifier, and a dithiol as a friction modifier. And a carbamate compound.

(Lubricating base oil)
The lubricating base oil is not particularly limited, and general base oils used in industrial gear oil compositions can be used. For example, mineral oil or paraffinic synthetic oil can be used.

  The mineral oil is not particularly limited, and a general oil used for industrial gear oil compositions can be used. For example, a refined oil obtained by refining a lubricating oil fraction of crude oil, or a further deeper removal after refining. A wax-treated deep dewaxed oil can be used.

  As the paraffinic synthetic oil, poly α-olefin, ethylene-α-olefin oligomer, or the like can be used.

  The content of the lubricating base oil is not particularly limited, but is a lubricating base oil other than the friction modifier and other additives described below, and is generally 90% by weight or more based on the entire gear oil composition.

(Friction modifier)
The friction modifier is added to reduce the friction coefficient of the gear oil composition, maintain a low friction coefficient, and obtain long-term wear resistance.

(Friction adjustment aid)
The friction adjusting auxiliary agent maintains and improves the performance of the friction adjusting agent by combining with the friction adjusting agent.

  As the friction modifier, at least an organic molybdenum compound and a dithiocarbamate compound are used.

  The organomolybdenum compound is not particularly limited, but molybdenum dialkyldithiocarbamate (MoDTC) or molybdenum dialkyldithiophosphate (MoDTP) is preferable from the viewpoint of reducing the friction coefficient and compatibility with the lubricating base oil.

  The organomolybdenum compound is added so that the molybdenum content in the gear oil composition is 50 ppm to 500 ppm. When the molybdenum content is less than 50 ppm, the effect of reducing the friction coefficient of the organic molybdenum compound cannot be obtained, and the friction coefficient of the gear oil composition cannot be lowered sufficiently. On the other hand, if molybdenum is contained at 500 ppm, the friction coefficient of the gear oil composition can be reduced, and it becomes uneconomical to contain more than 500 ppm. Therefore, an organic molybdenum compound is added so as to be 500 ppm or less. It is preferable.

A dithiocarbamate compound is generally used as an antioxidant, but by using it together with an organic molybdenum compound, the effect of reducing the friction coefficient is improved compared to the case where the organic molybdenum compound is used alone, A low friction coefficient can be maintained, and wear resistance can be maintained even when used for a long time. This is because the dithiocarbamate compound can activate the reaction of the organomolybdenum compound on the metal surface. That is, by adding organic molybdenum together with the dithiocarbamate compound, the organic molybdenum compound is promoted to be thermally decomposed into MoS ₂ by heat such as friction, and the effect of reducing the friction coefficient is improved and maintained. And wear resistance can be maintained.

  Examples of the dithiocarbamate compound include methylene bis (dibutyldithiocarbamate) and zinc dithiocarbamate (ZnDTC), and methylenebis (dibutyldithiocarbamate) is preferably used.

  The content of the dithiocarbamate compound is preferably 0.1 to 2.0% by weight with respect to the entire gear oil composition. When the content is less than 0.1% by weight, the synergistic effect with the organic molybdenum compound is not exhibited, the friction coefficient is not reduced, and the wear resistance is not sufficiently maintained. On the other hand, if the content is 2.0% by weight, a synergistic effect with the organic molybdenum compound is sufficiently obtained. Therefore, it is uneconomical to contain the dithiocarbamate compound in an amount of more than 2.0% by weight, so the content is preferably 2.0% by weight or less.

(Other)
In addition to the above-described lubricating base oil and friction modifier, various known additives can be added to the gear oil composition as necessary within a range not impairing the object of the present invention. For example, an antioxidant, an oily agent, a cleaning dispersant, a rust inhibitor, a metal deactivator, a pour point depressant, a defoamer, a demulsifier, and the like can be given.

(Gear oil composition production method)
The manufacturing method of the gear oil composition which consists of the above structures is not specifically limited, It can manufacture with the general manufacturing method of a gear oil composition.

  For example, a lubricating base oil can contain an organomolybdenum compound as a friction modifier and a dithiocation as a friction modifier.

A gear oil composition can be obtained by adding a bamate compound and, if necessary, various additives and mixing and stirring.

  The gear oil composition having the above-described structure contains a friction modifier that is a combination of an organic molybdenum compound and a dithiocarbamate compound in the lubricating base oil. The effect of reducing the coefficient is improved, and the low friction coefficient and wear resistance can be maintained. Therefore, the gear oil composition can maintain a low coefficient of friction, and has excellent wear resistance even when used for a long period of time. Therefore, the gear oil composition has a long life and can realize energy saving of the gear device.

  Specific examples to which the present invention is applied will be described below, but the present invention is not limited to these examples.

  In Example 1, trade name Brightstock (manufactured by JX Nippon Mining & Metals) and trade name Neutral Rack 500 (manufactured by JX Nippon Mining & Petrochemicals) are used as the lubricating base oil as mineral oils, and MoDTP is used as the friction modifier. And dithiocarbamate methylenebis (dibutyldithiocarbamate) (manufactured by Vanderbilt), and other antioxidants. In Example 1, an industrial gear oil composition was prepared by adding a friction modifier and the like to the lubricating base oil so as to have the formulation shown in Table 1, and mixing them. In addition, the compounding ratio shown in Table 1 was shown by weight ratio. In Examples 2 to 5, industrial gear oil compositions were prepared in the same manner as in Example 1 except that the blending ratio was changed as shown in Table 1.

  In Comparative Examples 1 and 2, industrial gear oil compositions were prepared using the materials and blends shown in Table 2, and in Comparative Examples 3 to 5, commercially available industrial gear oil compositions were used. As the friction modifier of Comparative Example 1, a molybdenum dithiophosphate FM agent (manufactured by Sanyo Chemical Industries, Ltd.) as an organic molybdenum compound was used as MoDTC. Comparative Example 3 is a mineral oil type and has a molybdenum content of 130 ppm. Comparative Example 4 is a mineral oil type and does not contain molybdenum. Comparative Example 5 is a poly-α-olefin system and does not contain molybdenum.

In Tables 1 and 2, the sulfur phosphorus extreme pressure agent 1 manufactured by Nippon Lubrizol Corp. was used, and the sulfur phosphorus extreme pressure agent 2 manufactured by AFTON CHEMICAL was used.

  Moreover, about the Example and the comparative example, the wear scar width | variety was measured by the method (LFW-1 friction test) based on ASTM-D-2714-94. The experimental conditions were a block material SAE01 H60, a ring material SAE4620, a rotation speed of 548 rpm, an oil temperature of 80 ° C., and a friction test for 30 minutes, and the wear scar width of the block was measured.

  As the deteriorated oil, a sample in which oxidative deterioration was promoted at 150 ° C. for 48 hours using a lubricating oil oxidation stability tester (ISOT) was used. The new oil is not oxidatively deteriorated.

  The coefficient of friction (SRV test) was measured for the examples and comparative examples. The friction coefficient was measured using an OPTIMOL SRV tester. As the test piece, a cylinder (Φ15 × 22 mm) material 100CR6 and a disk (Φ24 × 7.9 mm) material 100CR6 were used. The test conditions were as follows: load 400N, frequency 50Hz, amplitude 1.5mm, test temperature 40 ° C, 60 ° C, 80 ° C, 100 ° C, 120 ° C stepwise, each test time being 5 minutes, The coefficient of friction after operation was measured.

  Tables 3 and 4 show the results of the LFW-1 friction test and the friction coefficient test.

  From the results shown in FIGS. 1 and 2 and Tables 3 and 4, when a sulfur phosphorus extreme pressure agent and molybdenum dialkyldithiocarbamate were contained as in Comparative Example 1, the wear ratio in the LFW-1 test was The wear resistance after oxidative deterioration was 1.06. However, as shown in FIG. 1, in the SRV test, the reduction in friction coefficient does not start until 120 ° C., and the friction coefficient is high at other temperatures.

  Further, as in Comparative Example 2, when a sulfur phosphorus extreme pressure agent and molybdenum dialkyldithiophosphate were contained, the wear ratio in the LFW-1 test was 1.42, and the wear resistance after oxidative degradation was reduced. A decrease is observed. Also in the SRV test, the friction coefficient was high.

  In addition, even in the case of commercially available oils as in Comparative Examples 3 to 5, no compatibility between the wear resistance after oxidative degradation and the effect of reducing the friction coefficient was recognized.

  In comparison with these comparative examples, in Examples 1 to 5 containing molybdenum dialkyldithiophosphate and methylenebis (dibutyldithiocarbamate), as shown in FIG. 1, in the SRV test, the friction coefficient was reduced regardless of the temperature. The effect was recognized, the effect of reducing the friction coefficient in a wide temperature range, and the effect of reducing the friction coefficient in a wide temperature range. Moreover, as shown in FIG. 2, the wear ratio was as small as 1.04 to 1.06 in the LFW-1 test. From these results, by adding a combination of organic molybdenum and dithiocarbamate compound as a friction coefficient adjusting agent, the friction coefficient can be reduced, a low friction coefficient can be maintained, and the gear oil composition is deteriorated. It can be seen that the wear resistance can be maintained.

Claims (4)

  An industrial gear oil composition comprising a lubricating base oil and an organic molybdenum compound and a dithiocarbamate compound as a friction modifier.   The industrial gear oil composition according to claim 1, comprising 0.1 to 2.0% by weight of the dithiocarbamate compound. The organic molybdenum compound is molybdenum dialkyldithiocarbamate or molybdenum dialkyldithiophosphate,
The industrial gear oil composition according to claim 1 or 2, wherein the molybdenum content is 50 ppm to 500 ppm.   The industrial gear oil composition according to any one of claims 1 to 3, wherein the lubricating base oil is a mineral oil and / or a paraffinic synthetic oil.

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