JPH11172267A - Lubricating oil composition for bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lubricating oil composition excellent in lubricating properties, evaporation resistance, and lead resistance. SOLUTION: There is provided a lubricating oil composition used for a bearing made of a lead-containing alloy, wherein the base oil is a diester obtained from an alcohol and a dibasic fatty acid. The base oil is a diester obtained from an 8-14C monohydric alcohol and a dibasic fatty acid and having a total acid value of 0.1 mgKOH/g or below. This composition has improved properties such as lead resistance, so that it can provide good characteristics even when it is applied to a very simple structures such as, especially, oil-impregnated sintered bearings, sintered dynamic pressure bearings, iron-based oil-impregnated bearings, and dynamic pressure bearings each of which is made of a lead- containing alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil composition for bearings, which is used for industrially used bearings, particularly those containing lead.

[0002]

2. Description of the Related Art Along with an increase in demand for bearing-using equipment, a bearing maker uses a lead-containing alloy as one of bearing materials in order to improve workability in production or extreme pressure (lubricity) in function. I have used it. In addition, lubricating oils used for the same include, for example, poly-α-olefin hydrides, which are excellent in terms of metal corrosion resistance, particularly, lead resistance which does not cause generation of soap or gelation due to reaction with lead. Non-polar hydrocarbons have been used as base oils (JP-A 1-225697,
No. 9-48989, etc.).

[0003] However, hydrocarbon-based base oils have problems in lubricity and evaporation characteristics due to their nonpolar properties.
With the recent increase in the performance of equipment using bearings, the number of cases where bearings are used for high-speed rotation is increasing rapidly. If the bearing rotates at a high speed, the contact portion inevitably becomes hot. Therefore, there is a demand for a lead-resistant lubricating oil which is lead-resistant under high-temperature conditions and has excellent evaporation characteristics and lubricity.

JP-A-1-188592 discloses a lubricating oil for bearings in which a hindered phenolic antioxidant is mixed with a triester obtained from trimethylolpropane and a monovalent fatty acid in order to solve the above problem. However, both of the above-mentioned required characteristics, that is, the evaporation characteristic and the lead resistance, could not be satisfied.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a lubricating oil for bearings having excellent lubricity, evaporation and lead resistance.

[0006]

SUMMARY OF THE INVENTION The present invention provides a lubricating oil composition for a bearing for use in a bearing whose material is a lead-containing alloy, comprising a diester obtained from an alcohol and a divalent fatty acid as a base oil. Is what you do.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The diester used as a base oil in the present invention may be a diester obtained from a monohydric aliphatic alcohol and a dihydric fatty acid. And the like, and preferably dioctyl dimer. As the monovalent aliphatic alcohol, a linear or branched alcohol having about 8 to 14 carbon atoms is preferable, and as the divalent fatty acid, adipic acid,
Sebacic acid and dimer acid are preferred. The diester has a total acid value of 0.1 mg KOH / g or less, preferably 0.05 mg KOH / g or less. When the total acid value is large, not only the life of the base oil is drastically reduced, but also the thermal stability and lead resistance are reduced.

In the lubricating oil composition for bearings of the present invention, a detergent and dispersant may be added to the above-mentioned base oil, if necessary, in consideration of elongation of its life, as long as the object of the present invention is not impaired. Antiwear agents, viscosity index improvers, pour point depressants, ashless dispersants, antioxidants, metal deactivators, metal detergents, oil agents, surfactants, defoamers, friction modifiers, prevention Various additives such as a rust agent and a corrosion inhibitor can be blended according to the application. It is known that esters are superior to nonpolar hydrocarbons in terms of solubility in terms of the effect of additives. The base oil may contain a small amount of other lubricating oils, for example, a mineral oil-based lubricating oil. However, it is preferable that the amount of the lubricating oil be as small as possible because performance is deteriorated. It is better to stop.

The lubricating oil composition of the present invention has excellent lead resistance, and is therefore excellent for bearings in which the material of the bearing is a lead-containing alloy. The reason why the lead resistance is excellent is not clear, but is considered to be an effect unique to the ester of the present invention. In addition, by using a diester as a base oil, the action of a polar group in the molecule further improves lubricity due to the effect of adsorption to the surface of the bearing material, as well as evaporation resistance due to increased interaction between the molecules.

The lubricating oil composition for bearings of the present invention is impregnated into various types of sintered metal materials containing lead and used as sintered oil-impregnated bearings, sintered dynamic pressure bearings, iron-based oil-impregnated bearings, dynamic pressure bearings and the like. I do. Such sintered oil-impregnated bearings, sintered hydrodynamic bearings, iron-based oil-impregnated bearings,
Dynamic pressure bearings can be used as bearings for various devices, such as portable radio-cassettes, axial fan motors,
It can be applied to capstan bearings and motor bearings of stepping motors, portable CD players, portable MD players, and the like.

[0011]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Hereinafter, examples of the present invention will be described. In addition, a compounding ratio shows a weight part.

Examples 1 to 9 and Comparative Examples 1 to 18 Lubricating oil compositions for bearings of Examples 1 to 9 and Comparative Examples 1 to 18 were prepared by blending base oils and additives at the ratios shown in Tables 1 to 3. (Hereinafter referred to as lubricating oil).

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

[Table 3]

The component designations shown in Tables 1 to 3 are as follows. DIDA1: diisodecyl adipate Total acid value 0.01
mgKOH / g D8: Dioctyl dimer acid Total acid value 0.01 mgKO
H / g TM: Trimethylolpropane / caprylic capric acid mixed ester Total acid value 0.01 mg KOH / g DIDA2: Diisodecyl adipate Total acid value 0.07
mgKOH / g PAO: poly-α-olefin hydride (manufactured by Nippon Steel Chemical Co., Ltd .: Sinfluid 801; carbon number 30+: 96% by weight; carbon number 40+: 4% by weight) A1: 4,4′-methylenebis (2,6) -Di-t-butylphenol) A2: Dioctyldiphenylamine A3: Metal deactivator (benzotriazole derivative) A4: Succinate ester In addition, "Bal" in Tables 1 to 3 is numerically represented with 100 as a whole. The rest other than the thing is itself.

Table 4 shows the results of the lead resistance test and the evaporation test shown below for these lubricating oils. The lead resistance test was conducted by placing a 6 g sample in a φ60 petri dish, immersing granular lead in the dish, leaving it at 110 ° C. for 200 hours, and performing metal soap produced by reaction with lead by FT-IR. Was checked. In addition, the evaluation of the presence or absence of soap generation was evaluated as “Yes” when the FT-IR spectrum of the oil after the lead resistance test showed absorption near 1510 cm ⁻¹ derived from COO ⁻ Pb ⁺ . The fluidity of the oil after the test was also confirmed. The evaporation test is based on the old ASTM
The measurement was performed in accordance with D972 (204 ° C., 6.5 h), and the amount of each evaporation was measured.

[0018]

[Table 4]

In Table 4, the evaluation of the presence / absence of soap formation was made when the FT-IR spectrum of the oil in the lead resistance test showed that absorption near 1510 cm ^-1 derived from COO ^- Pb ⁺ was recognized. And

From the results in Table 4, Examples 1 to 9 of the present invention,
In particular, it can be seen that the samples of Examples 8 and 9 are excellent in both lead resistance and evaporation properties. Regarding the lead resistance, Examples 1 to 5 of the present invention were similar to the conventional hydrocarbon oils (Comparative Examples 13 to 18).
In 9 samples, no soap formation due to the reaction with lead was observed. Also, as is apparent from Comparative Examples 1 to 12,
Trimethylolpropane / caprylic capric acid mixed ester and diisodecyl adipate having a total acid value of 0.07 mg KOH / g were not lead-resistant. It is known that the addition of an antioxidant is effective in improving the oxidative deterioration of a base oil. However, as to the lead resistance, as apparent from Comparative Examples 4 to 6, the addition of these antioxidants is effective. It can be said that there is no improvement effect. Furthermore, by adding additives such as an antioxidant, a metal deactivator, and a rust inhibitor to a base oil having excellent lead resistance, the lead resistance does not decrease (Comparative Examples 4 to 5).
6, 10-12). With respect to the evaporability, the performance tends to be improved by adding additives such as an antioxidant, a metal deactivator, and a rust inhibitor. In particular, the effect of adding the ester is very effective, and the amount of evaporation can be suppressed to 1.0% by weight or less (Examples 8 and 9). However, as shown in Comparative Examples 16 to 18, the addition of an antioxidant, a rust inhibitor, and the like has conflicting effects of suppressing the evaporation amount and promoting a decrease in fluidity. is necessary.

Although the invention made by the present invention has been specifically described based on the embodiments, the present invention is not limited to the above, and it can be said that various modifications can be made without departing from the gist thereof. Not even. For example, a blended oil obtained by adding various additives such as a commercially available antioxidant, a detergent / dispersant, and an antiwear agent to the base oil of the present invention, a blended oil of the base oil of the present invention and a nonpolar hydrocarbon, or a mixture thereof A commercially available antioxidant in the oil,
Any lubricating oil such as a compounded oil to which various additives such as a cleaning dispersant and an antiwear agent are added may be used.

[0022]

As described above, the lubricating oil composition for bearings according to the first aspect improves various properties such as lead resistance by using a diester obtained from an alcohol and a divalent fatty acid as a base oil. Good characteristics can be obtained even with very simple structures such as sintered oil-impregnated bearings, sintered dynamic pressure bearings, iron-based oil-impregnated bearings, and dynamic pressure bearings, especially those containing lead. be able to.

Claims (3)

[Claims] 1. A lubricating oil composition for a bearing, wherein the lubricating oil is used for a bearing made of an alloy containing lead, wherein a diester obtained from alcohol and a divalent fatty acid is used as a base oil. 2. A monohydric aliphatic alcohol having 8 to 14 carbon atoms and a divalent fatty acid having a total acid value of 0.1 mgK.
The lubricating oil composition for bearings according to claim 1, wherein a diester having an OH / g or less is used as a base oil. 3. The bearing is a sintered oil-impregnated bearing, a sintered dynamic pressure bearing,
The lubricating oil composition for a bearing according to claim 1, which is an iron-based oil-impregnated bearing or a dynamic pressure bearing.