JP2000345178A - Heat-resistant lubricant composition and grease - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat-resistant lubricant composition which comprises the mixture of a specific alkyl-substituted diphenylsulfide with a specified alkyl- substituted diphenylether and can also be applied to lubricating greases used for bearings, gears, and the like, in industrial machines. SOLUTION: This composition comprises the mixture of (A) an alkyl- substituted diphenylsulfide of formula I [R1, R2 are each a 10 to 20C hydrocarbon; 1<=(m)+(n)<=-4] with (B) an alkyl-substituted diphenylether preferably in a component A/B weight ratio of 40/60 to 80/20. It is preferable that the component A or the mixture of the component A with the component B is used as a base oil in a grease comprising the base oil, a thickener and additives.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat-resistant lubricating oil composition, and more particularly to a heat-resistant lubricating oil composition comprising a mixed oil of an alkyl-substituted diphenyl sulfide and an alkyl-substituted diphenyl ether. The present invention relates to a heat-resistant lubricating oil composition applicable to lubricating grease used for bearings, gears and the like in industrial machines.

[0002]

2. Description of the Related Art In recent years, with the reduction in the size and weight of various machines and bearings, the speeding up of operation, and the maintenance-free operation, lubricating oil,
Since lubricating greases are used under severe conditions such as high temperature, high speed and high load, lubricating oils having better heat resistance and oxidation resistance are indispensable.
For example, in bearing lubrication, when the operating conditions are high temperature and high speed, the grease used for lubrication causes temperature rise due to oil film breakage, heat and oxidative deterioration due to high temperature conditions,
This leads to sludge formation, further damage to bearings, and a reduction in machine life. For this reason, various lubricating greases that can be used under high-temperature conditions have been studied.Generally, improvement under high-temperature conditions is based on the most common base oil, heat,
This is largely due to antioxidants that prevent oxidative degradation.

[0003]

As such base oils having excellent heat resistance, polyphenyl ether, silicone oil, fluorine oil and the like are known. However, polyphenyl ether and fluorine oil are very expensive, and silicone oil is generally said to have a problem in lubricity. The balance between the price and the performance of the base oil is important in providing an inexpensive and high-performance grease. Recently, a heat-resistant grease using an alkylated diphenyl ether as a base oil has been known. Alkylated diphenyl ethers are excellent in thermal and oxidative stability, and are characterized by a small amount of evaporation and a small change in viscosity particularly when used under high temperature conditions. Such properties are difficult to obtain with other general-purpose synthetic lubricating oils, for example, α-olefin oligomers, alkylbenzenes, polyalkylene glycols, and ester-based oils, so that a relatively inexpensive and excellent heat-resistant grease can be provided. .

[0004] However, when an alkylated diphenyl ether is used as a lubricating grease base oil, it does not have particularly excellent wear resistance and can be said to be equivalent to hydrocarbon oils such as mineral oils and α-olefin oligomers. Therefore,
Despite the fact that there is no problem with heat resistance in high-speed, high-load bearing operation, etc., where heat resistance and lubricity are simultaneously required,
Since excellent lubricity cannot be obtained, there have been drawbacks such as an abnormal sound sometimes generated during operation of the machine. A solution to this problem is to use a mixture with an ester oil that has excellent lubricating properties.However, if the proportion of the alkylated diphenyl ether is reduced, the superior heat resistance and oxidation resistance of the alkylated diphenyl ether are obtained. Sex was often impaired.

In the future, the weight and size of machines and bearings will be reduced.
The maintenance-free grease lubrication conditions will be higher temperatures, higher loads, and higher speeds. In addition, extending bearing life and eliminating abnormal noise during machine operation will be important issues from the viewpoint of customer satisfaction. It is expected that. In order to cope with these problems, it is necessary to supplement the performance of the grease with the type of thickener used for lubricating grease and the compounding technology of various additives such as antioxidants, anti-wear agents, extreme pressure agents, rust inhibitors, etc. Although possible, its performance is greatly influenced by the performance of the base oil, which is the largest component in the grease composition.

An object of the present invention is to provide a heat-resistant lubricating oil which is excellent in heat resistance, oxidation resistance and lubricity in order to cope with grease used under severe conditions such as high temperature, high speed and high load. It is to provide a composition and a grease.

[0007]

SUMMARY OF THE INVENTION The present invention provides a heat-resistant lubricating oil composition comprising a mixture of an alkyl-substituted diphenyl sulfide represented by the formula (1) and an alkyl-substituted diphenyl ether represented by the formula (2). Pertaining to things.

[0008]

Embedded image(Where R¹And R²Is a hydrocarbon having 10 to 20 carbon atoms
And R is¹And R ²Are the same but different
May be used. Also, m and n are 1 ≦ m + n ≦
Indicates an integer of 0 or more that satisfies 4. )

[0009]

Embedded image (In the formula, R ¹ , R ² , m, and n are the same as above.)

The present invention also relates to a grease comprising a base oil, a thickener and an additive, characterized in that an alkyl-substituted diphenyl sulfide of the formula (1) is used as the base oil. A grease comprising a thickener and an additive, wherein a mixture of an alkyl-substituted diphenyl sulfide of the formula (1) and an alkyl-substituted diphenyl ether of the formula (2) is used as the base oil.

According to the present invention, an alkylated diphenyl sulfide and an alkylated diphenyl ether having a predetermined chemical structure are used in combination to exhibit stability higher than the heat resistance and oxidation resistance inherent to alkylated diphenyl ether, and provide excellent heat resistance and oxidation resistance. In addition to providing a heat-resistant lubricating oil exhibiting a synergistic effect exhibiting even better thermal stability than each alone by using the above-mentioned alkylated diphenyl sulfide and alkylated diphenyl ether particularly at a specific combination ratio. Particularly, it is suitably used for lubricating grease used at high temperatures.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The alkylated diphenyl sulfide of the present invention can be synthesized by using a general organic synthesis technique. For example, using a diphenyl sulfide and an α-olefin as starting materials, a general aromatic ring nucleus alkylation catalyst such as a Lewis acid-based homogeneous catalyst such as aluminum chloride or a solid acid heterogeneous catalyst such as activated clay as a reaction catalyst. The addition reaction easily proceeds by using. The ratio of diphenyl sulfide and α-olefin used in the reaction can be changed according to the target compound, the catalyst used in the reaction and the reaction conditions. When anhydrous aluminum chloride is used, an alkali neutralizer and activated clay are added to the reaction mixture after the reaction, followed by stirring, followed by filtration and distillation to obtain the target compound. The obtained compound can be further subjected to a decolorization treatment using activated clay according to the purpose.

[0013] The alkylated diphenyl sulfide thus obtained may be used in addition to mineral oil, α-olefin oligomers, polyol esters, diesters, polyalkylene glycols, alkylbenzenes, alialkylnaphthalenes for the purpose of imparting other characteristics. It is also possible to mix and use with synthetic oils such as.

The alkylated diphenyl sulfide used in the present invention is represented by the above formula (1). Examples of the hydrocarbon group having 8 to 24 carbon atoms include a linear or branched alkyl group. . Preferred hydrocarbon groups are alkyl groups having 10 to 20 carbon atoms, specific examples of which are decyl, undecyl, dodecyl, tridecyl, tetradecyl, untadecyl, hexadecyl,
There are a heptadecyl group, an octadecyl group, a nonadecyl group, an eicosyl group and the like, and those having these branches may be used. In the case of a hydrocarbon group having less than 10 carbon atoms,
When the amount of evaporation of the alkylated diphenyl sulfide becomes too large and the number of carbon atoms exceeds 20, the pour point becomes too high. In addition, such a hydrocarbon group may be bonded to any position of any aromatic ring of diphenyl sulfide having two aromatic rings. Further, the number of hydrocarbon groups to be provided to diphenyl sulfide is preferably such that the sum of n and m in the formula (1) is 1 to 4,
If it is larger than 4, the oxidative stability decreases, and if there is no hydrocarbon group, the vapor pressure becomes too high.

As the hydrocarbon-substituted diphenyl ether used in the present invention, a known alkylated diphenyl ether oil having a chemical structure in which an aromatic ring is bonded by an oxygen atom can be used.
Hydrocarbons having an alkyl group of from 4 to 4 are preferable, and such a hydrocarbon group is preferably a linear or branched alkyl group having 8 to 24 carbon atoms, particularly preferably 12 to 18 carbon atoms. .

In the heat-resistant lubricating oil composition of the present invention, 95 to 5% by weight of an alkyl-substituted product of diphenyl sulfide and 5-95% by weight of an alkyl-substituted product of diphenyl ether are mixed in the composition (blending ratio). I do. By mixing the alkyl-substituted product of diphenyl sulfide and the alkyl-substituted product of diphenyl ether in the above mixing ratio, a lubricating base oil having a desired viscosity can be obtained. The heat resistance of this mixed base oil is improved as compared with the case of using each alone, and the oxidation resistance and the wear resistance can be further improved.

More preferably, the mixing ratio is 40 to 80% by weight of an alkyl-substituted diphenyl sulfide and 20 to 60% by weight of an alkyl-substituted diphenyl ether. In this case, as is clear from the examples, both of the alkyl-substituted product of diphenyl sulfide and the alkyl-substituted product of diphenyl ether show superior thermal stability and exhibit a synergistic effect. The heat-resistant lubricating oil composition of the present invention may optionally contain additives such as an antiwear agent, an extreme pressure agent, an antioxidant, a viscosity index improver, a pour point depressant, a corrosion inhibitor and a rust inhibitor. It may be blended.

The heat-resistant lubricating oil composition thus obtained can be used under high-temperature conditions, such as grease base oil, jet engine oil, heat-insulated engine oil, gas turbine oil, continuously variable transmission oil, diffusion pump oil, rotary oil It can be used as pump oil, oil-impregnated plastic oil, oil-impregnated bearing oil, gear oil, bearing oil, hydraulic fluid and the like. Grease can be obtained by using the heat-resistant lubricating oil composition of the present invention as a base oil and blending it with a thickener and an additive.

In the present invention, an alkyl-substituted diphenyl sulfide of the formula (1) or a mixture of an alkyl-substituted diphenyl sulfide of the formula (1) and an alkyl-substituted diphenyl ether of the formula (2) is used as the base oil. can do. In this case, as is apparent from the embodiment, there is no generation of abnormal noise particularly during operation of the machine, which is excellent. When the compound of the formula (1) and the compound of the formula (2) are used in combination, the weight ratio of the compound of the formula (1) to the compound of the formula (2) should be 40/60 to 80/20. It is suitable. As a thickener, for example, metal soap,
Bentonite, silica gel, copper phthalocyanine, allyl urea and the like can be exemplified. Examples of the additive include an antioxidant and a rust inhibitor.

[0020]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto.

Reference Example 1 In a 10-liter four-necked flask equipped with a stirrer, a dropping funnel, a thermometer, a cooling tube and a nitrogen gas inlet tube, 2700 g (14.5 mol) of diphenyl sulfide and 54 g (0.4 g) of anhydrous aluminum chloride were placed. 4 mol), and the mixture was heated and stirred at 70 ° C. in a nitrogen atmosphere to dissolve the catalyst, and then the temperature of the reaction system was raised to 160 ° C. Under a nitrogen flow, a mixture of 3013 g (18 mol) of 1-dodecene and 2367 g (12 mol) of 1-tetradecene was introduced into the above reaction system for about 120 minutes.
The mixture was added dropwise over a period of minutes to perform an addition reaction. After completion of the dropwise addition, the mixture was further stirred at 160 ° C. for 30 minutes, and then naturally cooled until the temperature of the reaction mixture reached 90 ° C.
Then, 0 g and 30 g of activated clay were added, and the mixture was heated and stirred for 90 minutes while maintaining the temperature at 80 to 90 ° C. Subsequently, the mixture was naturally cooled to 50 ° C., filtered under reduced pressure, and then distilled under reduced pressure to remove unreacted raw materials and monoalkyl adducts.
3,402 g of a hydrocarbon-substituted product of diphenyl sulfide comprising a dialkyl and trialkyl adduct was obtained. This synthetic oil is referred to as heat-resistant lubricating oil A.

Reference Example 2 Using a device similar to that of Example 1, 1702 g (10 mol) of diphenyl ether was placed in a four-necked flask having a volume of 10 L.
And 37 g (0.28 mol) of anhydrous aluminum chloride, and the mixture was heated and stirred to dissolve the catalyst. Under a nitrogen stream, a mixture of 2016 g (12 mol) of 1-dodecene and 1568 g (8 mol) of 1-tetradecene was dropped into the above reaction system in about 1 hour to carry out an addition reaction. The temperature during dropping is 110-
It was kept at 120 ° C. After completion of the dropwise addition, the mixture was further stirred for 30 minutes, and then naturally cooled until the temperature of the reaction mixture reached 90 ° C., 20 g of an alkali neutralizer and 20 g of activated clay were added, and the temperature was maintained at 80 to 90 ° C. The mixture was heated and stirred for 90 minutes. Subsequently, after natural cooling to 50 ° C., the mixture was filtered under reduced pressure, and then distilled under reduced pressure to remove unreacted raw materials and monoalkyl adducts. Obtained. This synthetic oil is referred to as heat-resistant lubricating oil B.

Examples 1 to 6 and Comparative Examples 1 to 2 Heat-resistant lubricating oil A and heat-resistant lubricating oil B were mixed in the proportions (% by weight) shown in Tables 1 and 2 to prepare lubricating oil compositions. .
About the obtained lubricating oil composition, a flash point, a pour point, a kinematic viscosity at 40 ° C. and 100 ° C., and a viscosity index were measured as general properties, and these results are also shown in Table 1. Further, a thermal stability test was performed on the obtained lubricating oil composition by the following method, and these results are also shown in Tables 1 and 2. Thermal Stability Test 50 g of the sample oil was weighed into a glass cup, and allowed to stand in a thermostat kept at 200 ° C. for 20 days, and the time-dependent change in the amount of evaporation (% by mass) and the state of the sample oil after the test were observed.

[0024]

[Table 1]

[0025]

[Table 2]

As is evident from the results in Tables 1 and 2, the compositions of Examples 1 to 6 have almost the same general properties as the alkylated diphenyl ether of Comparative Example 2, Heat resistance and oxidation resistance were remarkably excellent. In Examples 1 to 3, by mixing the hydrocarbon-substituted diphenyl sulfide with the alkylated diphenyl ether, a synergistic effect was observed on the change in the amount of evaporation at high temperature, and the hydrocarbon-substituted diphenyl sulfide and the alkylated diphenyl ether were mixed. There was better heat resistance than when each was used alone. As described above, a composition obtained by mixing a hydrocarbon-substituted diphenyl sulfide with an alkylated diphenyl ether is generally superior as a heat-resistant lubricating oil to an alkylated diphenyl ether generally used under high-temperature conditions. It had heat resistance and oxidation resistance, and was particularly satisfactory as various lubricating oils used at high temperatures.

Example 7 260 g of lithium 12-hydroxystearate was added to the heat-resistant lubricating oil A of Example 1 (1570 g), heated with stirring, poured into a stainless steel container, cooled, and then rolled with three rolls. Was performed once. 170 g of the above-mentioned heat-resistant lubricating oil A was added thereto, and milling was performed twice using three rolls to obtain a lithium soap grease.

Example 8 Using the procedure of Example 7, a grease having the composition shown in Table 3 was prepared. Table 3 also shows the results of measuring the penetration, dropping point, and oil release of each grease. Further, a lubricity test was conducted by the following method, and these results are also shown in Table 3.

Comparative Example 3 Using the procedure of Example 7, a grease using a heat-resistant lubricating oil B as a base oil was prepared. Lubricity Test Using a high-speed four-ball testing machine, the system was operated at room temperature for 1 hour at a rotational speed of 1200 rpm and a load of 40 kgf, and the occurrence of abnormal noise during the test and the wear scar diameter after the test were observed.

[0030]

[Table 3]

As is clear from Table 3, in the lubricating test, in the lubricating test, abnormal noise due to poor lubrication was generated, whereas in the greases of Examples 7 and 8, abnormal noise was generated. No, the wear scar diameter is smaller than the grease of Comparative Example 3 using an alkylated diphenyl ether as a base oil which is widely used as a grease base oil, and the composition using an alkyl-substituted diphenyl sulfide is It could be applied to base oils.

[0032]

As described above, according to the present invention, by using an alkyl-substituted diphenyl sulfide and an alkyl-substituted diphenyl ether in combination, the heat resistance and the oxidation resistance inherent to the alkyl-substituted diphenyl ether are improved. It has the advantage of exhibiting excellent heat-resistant lubricating oil. Furthermore, the combined use of the alkyl-substituted diphenyl sulfide and the alkyl-substituted diphenyl ether at a specific ratio shows superior thermal stability to both the alkyl-substituted diphenyl sulfide and the alkyl-substituted diphenyl ether, and a synergistic effect. Demonstrate.

Further, when an alkyl-substituted diphenyl sulfide or a mixture of an alkyl-substituted diphenyl sulfide and an alkyl-substituted diphenyl ether is used as a grease base oil, a conventional grease using an alkylated diphenyl ether as a base oil is used. The grease base oil can be provided without generating the abnormal noise shown in FIG.

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Claims (5)

[Claims] 1. A diphenyl sulphide represented by the formula (1)
Substituted alkyl and diphenyl represented by the formula (2)
Heat-resistant lubrication consisting of a mixture of alkyl-substituted ethers
Oil composition. Embedded image(Where R¹And R²Is a hydrocarbon having 10 to 20 carbon atoms
And R is¹And R ²Are the same but different
May be used. Also, m and n are 1 ≦ m + n ≦
Indicates an integer of 0 or more that satisfies 4. )(Where R¹, R², M and n are the same as above. ) 2. The heat-resistant lubricating oil composition according to claim 1, wherein the ratio of the compound of the formula (1) to the compound of the formula (2) is 40/60 to 80/20 by weight. 3. A grease comprising a base oil, a thickener and an additive, characterized in that an alkyl-substituted diphenyl sulfide of the formula (1) is used as the base oil. 4. A grease comprising a base oil, a thickener and an additive, wherein a mixture of an alkyl-substituted diphenyl sulfide of the formula (1) and an alkyl-substituted diphenyl ether of the formula (2) is used as the base oil. Grease characterized by the following. 5. The grease according to claim 4, wherein the ratio of the compound of the formula (1) to the compound of the formula (2) is 40/60 to 80/20 by weight.