JPS63210193A - Lubricating oil - Google Patents

Abstract

PURPOSE:To provide a low-cost lubricating oil having excellent lubricating ability, heat stabilizing and oxidation stability, which comprises a particular thiodipropionic acid ester as an active ingredient. CONSTITUTION:In the presence of a catalyst (e.g., p-toluenesulfonic acid), thiodipropionic acid (a) is reacted in an azeotropic solvent (e.g., toluene) with a 3-80C multibranched alcohol (b) (e.g., isotridecyl alcohol) in an (a) to (b) molar ratio of 1:2. Thus, there is obtd. a thiodipropionic acid ester (A) of the formula (wherein R1 and R2 are each an 8-30C multibranched alkyl). Component (A) in an amount of at least 5wt.%, pref. at least 10wt.%, is optionally compounded with additives (B) such as a mineral oil, other ester compds. (e.g., octyl oleate), other synthetic lubricating oils (e.g., polybutene), an antioxidant, an extreme pressure agent, a rust preventive, a defoaming agent, and a demulsifier.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a new synthetic lubricating oil, and more specifically, a synthetic lubricating oil that has thermal stability, oxidation properties, and This invention relates to a lubricating oil with excellent stability and lubricity.

[Conventional technology]

In recent years, with the demand for longer oil replacement periods, energy saving, and higher performance of machinery, the performance required of lubricating oils has become more severe, especially in terms of thermal stability and oxidation stability. However, there is a strong demand for lubricating oils that have particularly excellent properties.

In order to meet these demands, polyα-olefins, polybutenes, polyalkylene glycols, alkylbenzenes, alkylnaphthalenes, aliphatic diesters, polyol esters, phosphoric acid esters, etc., have been developed to provide improved oxidation stability,
Used in fields where thermal stability is required. for example,
Poly-α-olefins are used in automobile engine oil, gear oil,
For grease base oil, etc., polybutene for 2-stroke engine oil, compressor oil, etc., polyalkylene glycol for brake oil, hydraulic oil, quenching oil, etc., alkylbenzene for electrical insulation oil, refrigeration oil, etc., aliphatic ester for jet oil, etc. engine oil, automotive engine oil,
Phosphate esters are used in hydraulic fluids, grease base oils, precision machine oils, etc. However, these synthetic lubricants cannot withstand use under harsher conditions, and silicone-based synthetic lubricants, polyphenyl ethers, fluorine-based synthetic lubricants, etc. are also used, but they are all extremely expensive. Yes, the scope of use is limited.

[Problem that the invention seeks to solve]

As understood from the above explanation, expensive synthetic lubricants such as silicone-based synthetic lubricants, polyphenyl ethers, and fluorine-based synthetic lubricants are used under harsh conditions.
Its range of use is limited because it is expensive.

Therefore, an object of the present invention is to provide a synthetic lubricating oil that has particularly excellent thermal stability and oxidative stability and is inexpensive.

[Means for solving problems]

The present inventors have conducted intensive research to achieve the above object, and have discovered that a thiodipropionic acid ester having a specific structure can achieve the object.

That is, the present invention is based on the following general formula (% formula %) (in the formula, R,,R, are hyperbranched alkyl groups having 8 to 30 carbon atoms, and R1 and Rz may be different) The present invention provides a lubricating oil containing 5% by weight or more of thiodipropionic acid ester represented by:

The ester of the present invention is synthesized from thiodipropionic acid and a hyperbranched alcohol having two or more branches having 8 to 30 carbon atoms.

Examples of such hyperbranched alcohols include isononyl alcohol, isodecyl alcohol, isotridecyl alcohol derived from butylene dimer, propylene trimer, propylene tetramer, butylene trimer, butylene pentamer, propylene tetramer, etc.
Examples include isopentacosanol and isopentacosanol. However, it is not limited to the above.

2 moles of one or more of these alcohols and 1 mole of thiodipropion M are reacted with 10.1 to 1% by weight of p-)luenesulfone as a catalyst and toluene as an azeotropic solvent to obtain the thiodipropion of the present invention. Dipropionic acid ester is obtained. However, the method for synthesizing the ester of the present invention is not limited to the above method.

In addition to thiodipropionic acid esters, the lubricating oil of the present invention may also contain mineral oils and conventional ester compounds such as octyl oleate, oleyl oleate, butyl stearate, diisodecyl adipate, diisotridecyl adipate, dioctyl sebacate, trimethylolpropane. Tricaprylate, trimethylolpropane trioleate, neopentyl glycol di-2-ethylhexanoate, pentaerythritol tetracaprylate, etc., or other synthetic lubricating oils such as polyalphaolefins, polybutenes, polyalkylene glycols, alkylbenzenes, alkylnaphthalenes , polyphenyl ether, alkyldiphenyl ether, silicone-based synthetic lubricating oil, and other lubricating oil components may also be blended. However, the lubricating oil components to be blended are not limited to the above. At that time, the ester of the present invention is blended in an amount of 5% by weight or more. Preferably 1
It is 0% by weight or more. If it is less than 5% by weight, the excellent thermal oxidative stability of the ester of the present invention cannot be exhibited.

In addition, various known additives such as antioxidants, extreme pressure agents, rust preventive agents, antifoaming agents, and demulsifiers can be added as necessary.

Examples of antioxidants include phenolic antioxidants such as 2,6-di-t-butyl-4-methylphenol and 4,4'-methylenebis (2,6-di-t-butyl-phenol), p, p' -dioctyl phenylamine, monooctyldiphenylamine, phenothiazine, 3,7-cyoctylphenothiazine, phenyl-1-naphthylamine,
Phenyl-2-naphthylamine, alkylphenyl-1
- Examples include amine antioxidants such as naphthylamine, alkylphenyl-2-naphthylamine, sulfur-based antioxidants such as alkyl disulfide, thiodipropionic acid ester, benzothiazole, zinc dialkyldithiophosphate, zinc diallyldithiophosphate, etc. . Examples of the extreme pressure agent include zinc dialkyldithiophosphate, zinc diallyldithiophosphate, dialkyl polysulfide, triallyl phosphate, and trialkyl phosphate. As rust inhibitors, alkenyl succinic acid, alkenyl succinic acid derivatives, sorbitan monooleate, pentaerythritol monooleate, glycerin' monooleate,
Examples of antifoaming agents such as amine phosphate include silicone oils such as dimethylpolysiloxane and organosilicates such as diethyl silicate. Examples of the demulsifier include polyoxyalkylene glycol, polyoxyalkylene alkyl ether, polyoxyalkylene alkylamide, polyoxyalkylene fatty acid ester, and the like. However, it is not limited to the above.

In addition, emulsifiers, dispersants, etc. are added to emulsify and disperse in water.
It can also be used as a water-based lubricant.

The lubricating oil of the present invention can be used as hydraulic oil, metal working oil, compression oil, grease base oil, heat transfer oil, engine oil, turbine oil, turbocharger oil, etc., which are common usage forms of lubricating oil. It is particularly effective in fields where high temperature stability and lubricity are required.

〔Example〕

The present invention will be explained by examples, but the present invention is not limited to these examples.

Manufacturing example 17! A three-hole flask was equipped with a stirrer, a thermometer, and a dehydration tube with a condenser.

89.1 g (0.5 mol) of thiodipropionic acid and 200 g (1.0 mol) of isotridecyl alcohol derived from propylene tetramer were placed in the flask, and 0.87 g (0.5 mol) of p-toluenesulfonic acid was added to the flask. , 3% by weight) and 100 mZ of toluene were added and the esterification reaction was carried out for 6 hours under toluene reflux, and 18 g of water was distilled out. After removing toluene under reduced pressure, p-)toluenesulfonic acid was removed by filtration to obtain thiodipropionate Nal of the present invention. In a similar manner, the ester 2.3.4 of the present invention was obtained from a hyperbranched alcohol derived from propylene or butylene polymers.

Example 1 The thiodipropionic acid ester obtained in the production example, Le! ! 1
The viscosity and thermal oxidation stability of Examples 1 to 4 were examined along with Comparative Examples 5 to 9. The results are shown in Table-1. The method for measuring thermal oxidative stability is as follows.

+11 300°C decomposition rate Indicates the rate (%) of weight loss of the sample at 300°C when heated at a heating rate of 5°C/min in an air atmosphere using a thermal analyzer (TG) manufactured by Rigaku-kenki. Ta.

(2) Thermal stability test According to lubricating oil thermal stability test (JIS K-2540),
A 20 g sample was left in an air oven at 170° C. for 2 days, and the rate of increase in viscosity, increase in acid value, and state of sludge generation were examined. The viscosity increase rate was expressed as a percentage by dividing the sample viscosity increase due to the thermal stability test by the sample viscosity before the test. The increase in acid value was determined by subtracting the acid value of the sample before the test from the acid value of the sample after the test. In addition, the sludge condition was visually judged, ◎, 0. Judgment was made in four stages: △ and ×.

Table-1 POj C11zCH(CI++)0 As is clear from Table-1, the lubricating oils of thiodipropionic acid pigeons 1 to 4 of the present invention are all lubricating oils of the prior art such as mineral oil, polyα-olefin, Compared to fatty acid esters such as diisotridecyl adipate and trimethylolpropane, and polyalkylene glycols, 300℃ by TG
It can be seen that this is an excellent heat-resistant synthetic lubricating oil in terms of decomposition rate and thermal stability test results according to JIS K-2540.

Example 2 The thermo-oxidative stability of a lubricating oil in which thiodipropionic acid ester A3 was blended with mineral oil (150 N) and Acid 2 was blended with diisotridecyl adipate was similarly measured. The results are shown in Table-2.

Table 2 As shown in Table 2, when the content is less than 5% by weight, the thermooxidative stability of the ester of the present invention cannot be exhibited.

Example 3 1'1 The lubricity of the thiodipropionic acid esters 11 to 4 of the present invention was measured together with Comparative Examples 1 to 9. The results are shown in Table-3. The friction coefficient was measured using the Soda pendulum test (
60℃), and the seizure load was determined by the shell 4-ball test (room temperature).
I went there.

Table 3 Nos. 1 to 4 are mineral oil, which is a conventional lubricating oil;
Compared to polyalphaolefin, fatty acid esters such as diisotridecyl adipate, trimethylolpropane, and polyalkylene glycol, it has a lower coefficient of friction in the Soda pendulum test, a higher seizure load in the shell four-ball test, and excellent lubricity. It turns out that it is a synthetic lubricant.

Claims (1)

[Claims] The following general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (1) (Formula R_1 and R_2 are hyperbranched alkyl groups having 8 to 30 carbon atoms, and R_1 and R_2 are different. A lubricating oil containing 5% by weight or more of a thiodipropionic acid ester represented by the following.