JPH07305079A - Lubricating oil - Google Patents

Abstract

PURPOSE:To obtain a lubricating oil containing a specific polyether polyol fatty acid ester, combinedly having high heat stability, low pour point, high oil film characteristics and biodegradability and suitable for engine oil, lubricating oil for rolling, industrial gear oil, etc. CONSTITUTION:This lubricating oil containing a polyether polyol fatty acid ester is obtained by adding (B) 1-10mol, preferably 3-10mol of an alkylene oxide (e.g. ethylene oxide) to (A) a di- to hexa-hydric neopentyl polyol having no hydrogen atom in a carbon at beta-position and esterifying the addition product with (C) 8-22C fatty acids (e.g. caprylic acid). Furthermore, the lubricating oil can as necessary be blended with an extreme pressure agent, a cleaning and a dispersing agent, a fluidity-lowering agent, etc.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention can be suitably used for rolling lubricants, engine oils such as 2-cycle and 4-cycle lubricating oils, industrial gear oils, hydraulic oils and textile lubricating oils. In particular, the present invention relates to a lubricating oil that has high thermal stability, low pour point, high oil film characteristics, and biodegradability.

[0002]

2. Description of the Related Art In recent years,
With the rapid development of various machine industries, the operating conditions of lubricating oil have become severe, and a lubricating oil having excellent lubricating properties has been required.

In the case of rolling oil, for example, the progress of thin steel sheet manufacturing technology has been remarkable, and the demand for rolling oil has diversified. For this reason, conventional mineral oil-based oils and fats-based oils have been converted to synthetic oil-based oils. In addition, from the standpoint of improving the environment for thin plates and rolling, it is necessary to prevent fouling of mills and rolling oil equipment and to reduce fume. Therefore, lower melting point and lower concentration of rolling oil are required, resulting in significant improvement of lubricity. Is being pursued.

However, the synthetic oil used at the present stage (for example, Japanese Patent Laid-Open No. 3-172392) is still a mixed system with mineral oil and natural fats and oils, and therefore has good lubricity but poor workability. That is, the number of carbon atoms in the rolling oil is 12 to
Since it contains 18 linear higher saturated fatty acid monocarboxylic acids, its melting point has not been lowered, and since it contains linear unsaturated fatty acid monocarboxylic acids, it has a problem of poor thermal stability. is there. As described above, there is still no rolling oil satisfying high thermal stability, low fluidity and high oil film property.

On the other hand, with regard to engine oil, the required performance has become more severe due to the speeding up of automobiles and the expansion of highways, and the demand for higher output is becoming severer year by year. On the other hand, it has become difficult to meet these requirements with the performance of conventional automobile engine oils due to the installation of a purification device. In addition to excellent thermal stability, low-temperature fluidity, low-temperature startability, sludge dispersibility, and wear prevention, the performance required for future automobile engine oils will be extended as well as the engine oil life, that is, the oil change period. Or, it is unnecessary, and further reduction or elimination of various additives to the engine oil is required.

Hitherto, ester-based lubricating oils have been proposed as high-performance lubricating oils for rolling oils and engine oils. Neopentylpolyol was used as a component of the polyhydric alcohol in the ester and compared as a fatty acid component. A linear saturated fatty acid monocarboxylic acid having a small carbon number of 10 or less is used, and these neopentylpolyol esters are mixed with mineral oil to be used as an automobile engine oil in an internal combustion engine. (Kaisho 46-6528, JP-A-48-27867, JP-A-50-11685).

Lubricating oils based on these neopentyl polyol esters are known to have excellent heat and oxidation stability as compared with conventional mineral oils and general ester oils. In fact, there are examples of use as a base oil such as grease, hydraulic oil, metalworking oil (rolling oil), engine oil, or as an additive in the field of application that makes use of this characteristic.

[0008] However, neopentyl polyol ester is superior in heat and oxidative stability as compared with other ester type lubricating oils, but on the other hand, low temperature fluidity which is an important property as a lubricating oil base. In terms of sex, it is still inadequate and significantly inferior to diester oils such as dioctyl sebacate (DOS). Further, due to this drawback, the conventional neopentyl polyol ester lacks versatility. Further, regarding the lubricity, the alkyl chain length of the fatty acid constituting the ester is restricted to maintain the fluidity, so that the one having a carbon number of 10 or less is inevitably used. For this reason, lubricity and oiliness were also insufficient.

Further, in order to lower the pour point and improve the lubricity, a neopentylpolyol ester (Japanese Unexamined Patent Publication No. 59-133297) using an oleic acid having a double bond and an alkyl chain length is used. Although proposed, it has a problem of poor heat and oxidative stability because it has a double bond.

Further, regarding a metalworking oil agent and a metalworking method, a lubricating oil having a high workability and a good degreasing property (water solubility) has been proposed (JP-A-4-20).
598).

This lubricating oil comprises a linear olefin and a polyether polyol fatty acid ester, an alkali or an amine soap as an emulsifier.

However, in this proposal, a polyether polyol fatty acid ester is used as an emulsifier, and since it uses an olefin, its biodegradability is poor,
It is not preferable from the environmental aspect.

In addition, an ester-based lubricating oil for refrigerating machines using a 1,1,1,2-tetrafluoroethane refrigerant has been proposed (JP-A-4-146995).
However, although this proposal has the characteristics of compatibility with a refrigerant and low hygroscopicity, it does not have a sufficiently satisfactory performance.

The present invention has been made in view of the above circumstances, and is excellent in thermal stability and oxidation stability as well as in low temperature fluidity and lubricity, and is suitable for use in rolling oil, engine oil and the like. The purpose is to provide a lubricating oil.

[0015]

Means and Actions for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the present inventor has found that 2 to 6 carbon atoms in the molecule do not have a hydrogen atom as a component of a polyhydric alcohol. Use a polyol polyol fatty acid ester obtained by esterifying 1 to 10 mol of an alkylene oxide group added with a divalent neopentyl polyol with a fatty acid having 8 to 22 carbon atoms as a lubricating oil component The lubricating oil has excellent thermal stability and oxidative stability as well as low temperature fluidity, lubricity, and biodegradability.By controlling the number of moles of alkylene oxide added, the kinematic viscosity can be adjusted according to the application. The present invention has been accomplished by discovering that it is a high-performance lubricating oil that can be freely changed by various methods and has a wide range of applications.

Therefore, according to the present invention, a fatty acid having 8 to 22 carbon atoms is obtained by adding 8 to 10 mol of an alkylene oxide group to a 2 to 6 valent neopentyl polyol having no hydrogen atom at the β-position carbon in the molecule. Provided is a lubricating oil containing a polyether polyol fatty acid ester obtained by esterification with a class of compounds.

The present invention will be described in more detail below. The polyhydric alcohol used to obtain the polyether polyol fatty acid ester used in the lubricating oil of the present invention does not have a hydrogen atom at the β-carbon in the molecule. 2-6
A divalent neopentyl polyol, and examples thereof include neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, trimethylol hexane, ditrimethylol propane, pentaerythritol, dipentaerythritol, and the like. Can be used alone or in admixture of two or more.

As the alkylene oxide used for addition, ethylene oxide, propylene oxide, isopropylene oxide, butylene oxide,
One kind of isobutylene oxide or the like can be used alone or in combination of two or more kinds. The number of added moles is in the range of 1 to 10 mol, preferably 3 to 10 mol, based on the polyhydric alcohol. If the number of moles added is less than 1 mole, the effect of addition will not be exhibited, and if it is more than 11 moles, the oxidation stability will be poor. In addition, when adding two or more kinds of alkylene oxides, they may be block-like or random.

On the other hand, the fatty acids used for the esterification have 8 to 22 carbon atoms, preferably 11 to 18 carbon atoms, and may be linear or branched. If the carbon number is 7 or less, the desired load resistance cannot be obtained, and if the carbon number is 23 or more, the low temperature fluidity is not improved. Examples of such fatty acids having 8 to 22 carbon atoms include caprylic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, isostearic acid, oleic acid,
Mention may be made of arachidic acid, behenic acid and their lower alkyl esters. The lower alkyl preferably has 1 to 4 carbon atoms.

The lubricating oil of the present invention contains the above polyether polyol fatty acid ester as a main component, but if necessary, an extreme pressure agent, a detergent dispersant, a fluidity-lowering agent, an oxidation stabilizer and the like may be added. it can.

[0021]

The lubricating oil according to the present invention has remarkably improved lubricating characteristics, low temperature fluidity, and thermal / oxidative stability as compared with conventional lubricating oils. In addition to oil, it can be suitably used as a wide range of industrial lubricating oils such as flame-retardant hydraulic oil and grease.

[0022]

EXAMPLES Hereinafter, the present invention will be specifically shown by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Polyether polyol fatty acid esters were prepared using the polyhydric alcohol alkylene oxide adducts and fatty acid esters shown in Table 1 below. The manufacturing methods of Examples 2, 3, and 5 are shown below.

<Example 2> Reflux condenser, thermometer,
In a glass reactor having a capacity of 500 ml equipped with a stirrer, 80 g (0.296 mol) of a 3 mol adduct of trimethylolpropane ethylene oxide, methyl caprate 198.
6 g (1.066 mol) and sodium methylate 1.
Add 4g (0.5wt% to the charge), 220 ℃, 11
The reaction was carried out at 0 torr for 6 hours. 112g after the reaction
After washing twice with water to remove the catalyst, residual methyl caprate is topped at 220 ° C. and 0.3 torr, the reaction system is filtered, and 213 g of polyether polyol fatty acid ester (yield 98%) is yellow and transparent. A liquid was obtained.

<Embodiment 3> Reflux condenser, thermometer,
In a glass reactor with a capacity of 500 ml equipped with a stirrer, 70 g (0.226 mol) of trimethylolpropane propylene oxide 3 mol adduct, methyl caprate 15
0.9 g (0.81 mol) and 1.1 g of sodium methylate (0.5 wt% with respect to the charge) were added, and 90 ° C., 9
The reaction was carried out at torr for 4 hours. After completion of the reaction, the catalyst was removed twice by washing with 100 g of water, residual methyl caprate was topped at 220 ° C. and 2 torr, and the reaction system was filtered to remove the polyether polyol fatty acid ester 170.
g (98% yield) of a yellow transparent liquid was obtained.

<Embodiment 5> Reflux condenser, thermometer,
In a glass reactor with a capacity of 500 ml equipped with a stirrer, 70 g (0.226 mol) of trimethylolpropane propylene oxide 3 mol adduct, methyl laurate 17
3.3 g (0.81 mol) and 1.2 g of sodium methylate (0.5 wt% based on the charge) were added, and the mixture was heated at 90 ° C. for 5
The reaction was carried out at torr for 4 hours. After completion of the reaction, the catalyst was removed twice by washing with 100 g of water, residual methyl laurate was topped at 220 ° C. and 1 torr, the reaction system was filtered, and polyether polyol fatty acid ester 187 was added.
g (97% yield) of a yellow transparent liquid was obtained.

[0027]

[Table 1]

For the polyether polyol fatty acid esters obtained in the examples and comparative examples shown in Table 1, the kinematic viscosity, viscosity index, pour point, friction coefficient, load bearing capacity, hot tube test, and oxidation stability were determined according to the following methods. The test was conducted. In addition, as rolling oil, pour point, friction coefficient, load bearing capacity, and value of oxidation stability test are important, and as engine oil,
The values of viscosity index, pour point, friction coefficient, load bearing capacity, hot tube test, and oxidation stability test are important. The results are shown in Tables 2 and 3. <Test method> Kinematic viscosity: In accordance with JIS K2283 Viscosity index: In accordance with JIS K2283 Pour point: In accordance with JIS K2269 Friction coefficient: In accordance with pendulum type oil friction tester specifications Load capacity: In accordance with JIS K2519 Hot tube test: Test Temperature: 300 ° C, test time 16 hours, air flow rate 10
± 0.5 cc / min Test oil flow rate: 0.31 ± 0.01 cc / min Oxidation stability test: In accordance with JIS K2514

[0029]

[Table 2]

[0030]

[Table 3]

From the results of Tables 2 and 3, the lubricating oil of the present invention was
Compared with the lubricating oil of Comparative Example, for example, when Examples 2 and 3 and Comparative Example 1 using the same polyhydric alcohol and saturated fatty acid and Example 5 and Comparative Example 2 are compared, respectively, the alkylene is clearly alkylene. It is recognized that the introduction of the group lowers the pour point and exhibits a high viscosity index and a high load bearing capacity. Further, it exhibits high heat resistance (hot tube test) and oxidation resistance stability. Therefore, the lubricating oil of the present invention is
It is recognized that it has excellent properties as an engine oil.

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Claims (4)

[Claims] 1. An esterification product of a fatty acid having 8 to 22 carbon atoms, which is obtained by adding 1 to 10 moles of an alkylene oxide group to a 2 to 6 valent neopentyl polyol having no hydrogen atom at the β-position carbon in the molecule. A lubricating oil containing a polyether polyol fatty acid ester obtained by 2. The neopentyl polyol is selected from neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, trimethylolhexane, ditrimethylolpropane, pentaerythritol and dipentaerythritol. Lubricant. 3. The lubricating oil according to claim 1, wherein the alkylene oxide group is selected from ethylene oxide, propylene oxide, isopropylene oxide, butylene oxide, and isobutylene oxide. 4. The fatty acid is selected from caprylic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, isostearic acid, oleic acid, arachidic acid, behenic acid and lower alkyl esters thereof. Item 4. The lubricating oil according to any one of items 1 to 3.