JPH04359997A - Hydrocarbon fluid composition - Google Patents

Abstract

PURPOSE:To improve the thermal oxidation stability by incorporating an organic sulfide compound and an alkylnaphthalene compound into a lubricating oil composition. CONSTITUTION:A lubricating oil composition containing at least one of a solvent refined mineral oil, a hydrotreated oil, and a synthetic base oil, or a mixture of this composition with a lubricating oil additive is mixed with an organic sulfide compound in an amount sufficient to provide a final sulfur content of 20 to 30,000ppm and 0.5-60wt.% alkylnaphthalene compound.

Description

[Detailed description of the invention]

0001

[Technical Field] The present invention relates to compositions of industrial lubricating oils such as hydraulic oils, compressor oils, and heat transfer oils, and automotive lubricating oils such as manual transmission oils, automatic transmission oils, differential gear oils, and shock absorber oils. Regarding.

0002

[Prior Art] Conventionally, lubricating base oils have been obtained by distilling crude oil at atmospheric pressure to remove gas and fuel components, distilling the residue under reduced pressure, and refining the effluent components using a solvent such as furfural to remove unstable components. Manufactured by. In this solvent refining method, the viscosity characteristics and color tone of oils that are too refined are improved, but the oxidation stability is deteriorated, so the natural mineral oil itself contains antioxidants. It has been discovered that this natural antioxidant is sulfur, an aromatic hydrocarbon compound [Lubrication, Vol. 2, No. 3]
No. (1957), p105-110]. Therefore, the thermal oxidative stability of refined base oil in conventional solvent refining methods is
Although it depends on the remaining amount of these natural antioxidants and the remaining amount of unstable components, or the balance thereof, as the degree of purification is increased, the amount of unstable components decreases and the natural antioxidants also decrease. . For this reason, in the refining of lubricant base oils by solvent refining, there are appropriate refining conditions called optimal solvent refining depth or optimal aromaticity. Regarding these phenomena, in addition to the above-mentioned documents, there are many documents, such as Larsenetal: Ind. Eng. Chem.
, 1942, 34, p183 and Denison: I
nd. Eng. Chem. , 1944, 36, p477
Many researchers have published on the subject. On the other hand, with the recent trend toward diversification of available crude oil brought about by the instability of crude oil availability, the hydrofinishing method (hydrofinishing, hydrogen chemical treatment or hydrocracking) has become commonly used as a method for producing refined base oils. This method involves adding hydrogen to aromatic hydrocarbons and cyclic hydrocarbons to convert them into high viscosity index hydrocarbon compounds that exhibit little viscosity decrease with temperature rise. Hydrogen, nitrogen compounds, etc. can be converted and removed, but sulfur compounds, etc., which are considered to be natural active ingredients, also disappear at the same time, so it was necessary to improve thermal oxidative stability. Furthermore, synthetic base oils such as olefin polymerized oils, diester oils, polyalkylene glycol oils, and halogenated hydrocarbon oils have recently become widely used in lubricating oils, but they do not themselves contain antioxidants, so Therefore, there was a need to improve thermal oxidation stability.

0003

[Purpose] Currently, industrial production equipment and automobiles, etc., are becoming smaller and more sophisticated from the viewpoint of energy conservation and power saving, and are used for purposes such as reducing friction loss, cooling, and cleaning friction parts. The lubricating oils used in such equipment are exposed to increasingly severe conditions, particularly high temperatures, and are subject to deterioration in a short period of time. When lubricating oil deteriorates, it needs to be replaced, but the process of re-supplying the lubricating oil and producing the lubricating oil used for this purpose is a labor-intensive and costly task. The invention is to provide a lubricating oil composition with excellent thermo-oxidative stability that is resistant to thermal and oxidative degradation.

0004

The present invention relates to a lubricating oil composition that has significantly improved resistance to thermal oxidative deterioration by using two components, an organic sulfide compound and an alkylnaphthalene compound, as essential components of the lubricating oil composition.

The organic sulfide compound used in the present invention is not particularly limited in type as long as it is oil-soluble, and the number of sulfide bonds and alkyl,
The type and number of allyl, phenyl, benzyl, etc. are also not particularly limited. Similarly, the type and number of hydrocarbon groups bonded to the naphthalene ring of alkylnaphthalene compounds are not particularly limited, and the alkylnaphthalene compounds may have any substituents other than hydrocarbons, such as hydroxy, amino, carbonyl groups, etc. You can.

[0006] The present inventors have found that when the above-mentioned organic sulfide compound and alkylnaphthalene are used in combination as a thermal antioxidant, they exhibit an excellent synergistic effect, as specifically shown in the following example. The present invention has been completed. The organic sulfide compound used in the present invention preferably has a sulfur content in the range of 20 to 30,000 ppm, and the alkylnaphthalene content is 0.
It is preferable to use the composition within a range of 5 to 60% by weight.

The fluids used in the present invention include solvent-refined mineral oils, hydrogenated oils, synthetic base oils, etc., which require the addition of thermal antioxidants, or lubricating oil additives added to these alone or in mixtures. It is a combination.

The above-mentioned reference "Lubrication" Volume 2, No. 3 (1957) describes t-dodecyl mercaptan and β
- The combined use of methylnaphthalene shows an antioxidant effect, and the Journal of the Japan Petroleum Society, Vol. 2, No. 2 (1959
) describes that the combination of dicetyl sulfide, cetyl mercaptan, etc. with α-methylnaphthalene exhibits antioxidant effects; There is no description suggesting the excellent effects achieved by using these two components together, or especially by using specific amounts of both. EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

EXAMPLE To determine the degree of thermal oxidative deterioration, a prepared sample lubricating oil is placed at a constant high temperature, and oxygen is blown into it to promote oxidation. It is also common to include an appropriate amount of copper catalyst to promote the oxidation reaction. Here, I
An oxidation test device specified in P-280 and commonly referred to as CIGRE was used. Details of the test conditions are as follows. Capacity of sample glass container: approx. 110ml Diameter of sample glass container: 2.60cm Amount of sample oil: 40
g Total surface area of copper catalyst…………11.46cm2
Shape of copper catalyst: 57mm linear x 4 Total surface area of iron catalyst: 5.73cm2 Shape of iron catalyst: 57mm linear x 2 Testing environment temperature...
……………130℃ Oxygen injection rate…16.7ml/min The resistance limit against thermal oxidative deterioration can be easily determined by the rapid increase in acid value, generation of bubbles, rapid increase in viscosity, etc. The time when this limit is reached is organized as the drag limit time. The sulfide sulfur compounds and naphthalene compounds involved in the results shown here as representative examples are as follows. Sulfide compound: Didodecyl polysulfide Sulfur content: 19.6%w Naphthalene compound: Monoalkylnaphthalene Straight chain alkyl carbon number = 16 to 18 The natural inhibitors are almost completely removed from the base oil to which these are added, and it is not suitable for practical use. This is a base oil that can be used in a hydroprocessing method with a sulfur content of 12 ppm, which requires the addition of a thermal oxidation inhibitor. Table a in Table 1 shows the results of adding 1, 3, and 10% w of alkylnaphthalene to the base oil without the addition of sulfide compounds, but the drag limit time without addition is 1.5 hours, and Even when 1, 3, and 10% w of is added, no extension of the drag limit time is observed, and it is the same as in the non-additive state. On the other hand, as shown in b in Table 1, the sulfide compound added so that the amount of sulfur added is 200 ppm shows a drag limit time of about 40 hours, and the sulfide sulfur compound itself also has a certain resistance to thermal oxidative degradation. I understand that. Furthermore, when 1, 3, and 10%w of alkylnaphthalene is added to this, the drag limit time reaches 70, 165, and >440 hours, indicating that the added alkylnaphthalene exerts a remarkable effect in the presence of sulfide sulfur compounds. is obvious. Therefore, the synergistic effect of adding a sulfide sulfur compound and a naphthalene compound became clear, and by creating a lubricating oil fluid containing these two components as essential additives, a lubricating oil fluid composition with significantly improved resistance to thermal oxidative degradation was obtained. .

[Table 1]

0010

[Effects] By using a specific thermo-oxidative stabilizer, the present invention provides a lubricating oil composition with excellent thermo-oxidative stability.

Claims (2)

[Claims] Claim 1: A lubricating oil composition containing solvent-refined mineral oil, hydrogenated oil, synthetic base oil, or a plurality of these, or a composition in which a lubricating oil additive is blended with these, an organic sulfide compound and an alkylnaphthalene. A lubricating oil composition containing the compound. 2. A lubricating oil composition containing solvent-refined mineral oil, hydrotreated oil, synthetic base oil, or a plurality of these, or a composition in which a lubricating oil additive is blended with the lubricating oil composition, containing 20 to 30,000 ppm of final sulfur. A lubricating oil composition containing an organic sulfide providing a content and an alkylnaphthalene compound having a final concentration of 0.5 to 60% by weight.