JPS58201895A - Oxidative stability improver for lubricant and method for improving oxidative stability - Google Patents

Abstract

PURPOSE:An oxidative stability improver containing a nonbasic nitrogen compound obtained from mineral oil by concentration and separation is added to a lubricant oil such as of mineral oil, alkylbenzenes, alkylnaphthalenes or mixtures thereof. CONSTITUTION:A nonbasic nitrogen compound obtained from mineral oil by concentration and separation such as carbazole or indole, their alkyl-substituted derivative is used as a major component to give an oxidative stability improver. The product is added to a lubricant, preferably by more than 16ppm based on the nonbasic nitrogen and less than 3ppm as the basic nitrogen. EFFECT:The improver shows high solubility in the lubricant oil.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving oxidation stability of lubricating oil using an oxidation stability improver and a rejuvenating agent for lubricating oil. More specifically, the improver of the present invention is an improver whose main component is a non-basic nitrogen compound concentrated and separated from mineral oil, and is used as a lubricating base oil such as mineral oil or alkylbenzene or alkylnaphthalene.

Oil used to fill electrical equipment, such as electrical insulating oil.

It is blended with oil used in heat transfer systems such as heat transfer oil or oil for the purpose of lubrication such as turbine oil (hereinafter referred to as lubricating oil), and has the effect of improving its oxidation stability. be.

For this purpose, so-called advanced purification means are generally employed to remove unstable components by solvent extraction, hydrogenation treatment, clay adsorption, etc. This method has limited performance improvement, reduces yield during purification, and requires a large amount of energy.

The present invention was developed and completed in order to solve the above problems. That is, the purpose of the present invention is.

Mineral oil-based N# lubricating base oil, alkyl aromatic lubricating base oil such as alkylbenzene, alkylnaphthalene, alkylpiphenyl, electrical insulation oil, couple oil.

Oxidation stability improver for oils filled in electrical equipment such as condenser oils, oils for lubricating effects such as turbine oils and refrigerator oils, mineral oils, or heat transfer oils containing the aforementioned alkylbenzenes. ) and K that provides methods of improvement. Hereinafter, the upper oil will be collectively referred to as lubricating oil.

The improver of the present invention has not been previously known, and when added to the lubricating oil, it significantly improves oxidation stability.

It can also be added to, for example, commercially available mineral oil-based, alkylbenzene-based or mixed electrical insulating oils.

The present invention will be explained in detail below.

The present invention is characterized by blending an oxidation stability improver for lubricating oil, which is characterized by having a non-basic nitrogen compound concentrated and separated from mineral oil as a main component, and by adding cut-and-cut into refined lubricating oil. This is a method for improving the oxidation stability of lubricating oil.

The configuration of the present invention will be explained in detail below. In the present invention, the non-basic silicon compound (hereinafter referred to as Nn compound).

The expressions basic nitrogen compound (hereinafter abbreviated as Nb compound), non-basic nitrogen component (hereinafter abbreviated as Nn component), and basic nitrogen component (hereinafter abbreviated as Nb component) are used. The meaning is as follows. A wide variety of organic nitrogen compounds are naturally present in mineral oil, including elemental nitrogen (N
) is known to exist mainly in the form of a peterocyclic compound, which is analyzed as having basicity.3 However, in the present invention, it is important to strictly distinguish between Nn and IJb. It is. In compound is a general term for nitrogen compounds containing a non-basic nitrogen element.
, Nn content refers to the total amount (weight percentage) of nitrogen elements having the above properties.

Nb compounds and Nb content are also related to basic nitrogen elements.

31 Measured by method.

Nt content: Measured by the method specified in J Engineering 8-21SO9-1980 "Nitrogen content test method for crude oil and petroleum products".

Nb content: Test method 4313 by UOP (United States)
-70 [Nitrogen Ba5es in Pf
3troleum distillates by cO
lor Indicator Titration J
Measured by the method specified in This measurement involves dissolving the sample oil in glacial acetic acid and titrating it with perchloric acid in glacial acetic acid using crystal violet as an internal indicator.

It is determined by the In fraction quadratic formula.

'Nn -Nt -Nb Therefore, since the Nn compound is a component that cannot be titrated by the above method among the total nitrogen components, it can be understood as an organic nitrogen compound with extremely weak basicity.

Usually in mineral oil or oil that has been hydrotreated.

Carbazole, indole, acridine, quinoline, β
Typical types are 7-toquinoline and tetrahydroquinolin-4-, and there are many types of alkyl derivatives of these, and these can be extracted by the above method to determine the nitrogen content present as an In compound and the nitrogen content present as an Nt) compound. However, in the present invention, the former is effective as an improving agent. Examples of Nn compounds include carbazole, indole, and alkyl substituted products thereof.

The Nn compound is concentrated and separated from mineral oil and used as an improver.

The mineral oil used as a raw material is the residual oil obtained by atmospheric distillation of one or more types of crude oil, such as nandene group, mixed group, or paraffin group crude oil, or the distillate obtained by further vacuum distillation, or the vacuum distillation residue such as price dock. Any one or more of the deasphalted oils may be used. The mineral oil is unrefined mineral oil (U
Although it may be used as a raw material as it is, mineral oil (hereinafter abbreviated as HF oil) obtained by NML or UR oil or HF oil can be used as a raw material as is.
Mineral oil c obtained by solvent extraction F# of oil with a known solvent
(hereinafter abbreviated as EX oil) may be used as a raw material. However, in solvent extraction, it is necessary to select mild conditions because nitrogen compounds are easily removed in the vicinity. In addition to the nitrogen compounds originally present in the crude oil, HF oil contains nitrogen compounds that have been partially nuclear hydrogenated through hydrogen treatment, but this is not a particular problem.

HF oil or EX oil is subjected to dewaxing or solid adsorption refining using activated clay (ah process) in normal base oil production, but mineral oil obtained through these processes (referred to as OA oil) may also be used.

I (F oil has a lower sulfur content than UR oil, so N
Since the sulfur content in the n-concentrate is low and the content of Nb compounds in the OA oil extraction is even lower, the operation for obtaining the n-concentrate is facilitated. There are no restrictions on the sulfur content or hydrocarbon composition of the raw mineral oil used, so the UR oil, HF
Oil, Ex oil.

Any one type or more than one type of OA oil may be used. The Nn compounds contained in these are concentrated and separated.
At this time, in order to prevent the Ml) compounds from being separated at the same time,
Care should be taken to ensure that the Nb compound is not contained in the Nn compound concentrate. The presence of Nl) compounds interferes with the effectiveness of Nn compounds.

Preferably, the Nb compound should not be contained in the improver of the present invention, but the effect of the Nn compound can be effectively exhibited as long as the Nb content is 5% or less relative to the Nn content.

In order to selectively concentrate and separate Nn compounds from the raw mineral oil, the mineral oil is adsorbed with an agent capable of adsorbing Nb components, such as activated clay, and the resulting oil is further brought into contact with silica gel to remove Nn components. The Nn compound is eluted by adsorbing and then eluting the adsorbed silica gel with a methanol/methylene chloride solvent. The solvent may be removed by evaporation under a nitrogen stream.

The eluate obtained by K in this manner does not substantially contain Nt) compounds, is concentrated in Nn compounds, and also contains sulfur compounds.

A cation exchange resin is effective instead of the activated clay, and alumina or Florisil is also effective instead of silica gel. U
Improvers separated from R oils, HF oils, mx oils or 7-OA oils, ie concentrates of Nn compounds, are all effective in improving oxidative stability.

For example, Kraate! Viscosity 11c obtained from crude oil
When the 8t (40°C) fraction (UR oil) is treated with the above method, Nn 1.22 wt%, S 6.5 wt%
improver obtained by hydrorefining UR oil)
(If F oil (desulfurization rate 70%) is treated in the same way, Nn
An improver of 2.30 wt%, S 4.6 vttq6 is obtained. When the raffinate oil after 20 vol14 extraction was treated with HF oil as an extract using a furfural solvent, Nni 5 wt'%, 81. O
wt % of the roughness improver is obtained. This has the function of improving oxidation stability without significant difference. arabian light crude oil,
Nn concentrates separated from Basra crude oil and the like have an equivalent effect.

Of the above means, consideration must be given to sufficient adsorption of Nb components by activated clay or cation exchange resin, because if Nl) is present at about 1/20th or more of Nn,
This is to reduce the effect of the n component.

=8 - The improver of the present invention exhibits the effect of significantly improving oxidation stability when added to refined lubricating oil. The amount added varies depending on the purpose of improvement, but approximately 1
The content is preferably 4 ppm or more, more preferably 16 ppm or more. It is particularly effective for highly refined mineral base oils, mineral oil-based lubricating oils, or mixed lubricating oils such as alkylbenzene, alkylnaphthalene, or mineral oil and alkylnaphthalene. More specifically, it is effective for the base oil or lubricating oil in which the total nitrogen content (Nt) is several ppm or less.

Even if Nt is low, the improver of the present invention does not work effectively on lubricating oils containing 5 to 5 ppm or more of Ml). Ordinary commercially available electrical insulating oil.

Since it is highly purified and contains Nt of several ppm or less, the use of the improver of the present invention is effective. It is also effective for insulating oils containing alkylbenzenes and alkylnaphthalenes.

There is no need to limit the presence of sulfur (0.02~0
．． Blended in refined mineral oil with a sulfur content of 9 wt%.

The effect was confirmed. However, since refined mineral oils are generally obtained for the purpose of removing sulfur compounds, the improver of the present invention is generally blended into lubricating oils having a sulfur content of about 0.02 to 0.7 wtqlJ.

The improver of the present invention is liquid paraffin and polybutene.

Since it easily dissolves in polyα-olefins, etc., it can be used in combination with host nitrogen compounds.

For example, it is possible to use 1s or more of indole, 2-methylindole, 3-methylindole.

The improver of the present invention was added to a commercially available electrical insulating oil (viscosity 10.9 cS).
t040℃, sulfur content 0.03 wt%, Nt2,
Oppm, NbO, 2ppm, J Engineering S-0
-2101 standard oxidation stability test total acid value 0.20■
KO1-17t), and the Nn after blending was 16p.
By setting pm and Nb to 0.2 ppm, the total acid value became 0.08 ■KOH/l. Also, alkylbenzene (total acid value 6.50 t), which is officially used in electrical insulating oil,
llfKOH/f) to make Nn 24 ppm, the total acid value was 0.04+vxoa/r.

The improver of the present invention is mineral oil, alkylbenzene.

It has excellent solubility in alkylnaphthalenes and the like, and when added up to a concentration of 500 ppm, it exhibited an excellent effect of improving oxidation stability.

The contents of the present invention will be explained below based on examples.

Example 1 Vacuum distillation distillate oil (referred to as UR oil) of kraate crude oil (viscosity 40°C, 12.49 ast, sulfur content 2.46
wt%, total nitrogen content 420 ppm) fNi-Oo-
Using a Mo-supported alumina catalyst, hydrogen pressure was 35 (gauge), temperature was 335°C, and space velocity (LH8V) was 1.5.
Hydrorefining was carried out under the conditions of hr-' to obtain HP oil. This was then subjected to solvent extraction using furfural solvent (solvent ratio 250
%, temperature 45°C) to obtain a raffinate, the solvent was evaporated and E
X oil was obtained at 8-40°C in the presence of methyl ethyl ketone.
The DW oil was cooled and dewaxed to obtain a DW oil, and the DW oil was further treated with activated clay (1.5 wt% of the oil was used) to obtain an OA oil. OA oil was a highly refined mineral oil and had the properties shown in Table 1.

Table 1 Note 1) Time until oxygen pressure drops by 30 mHg at 145°C x 1 atln (oxygen) in the presence of insect catalyst Nn Baked at 140℃ for 4 hours) to oil for 5. Owt%, 4.5 wtqb added, 45°C, 1
Silica gel (Wako Gel C-100) was prepared by splitting the solution (oil) into a glass column for 14 hours after contacting with stirring for an hour.
(activated at 0°C for 5 hours) passed through an adsorption bed. The silica gel adsorption layer was washed with pentane, then twice with a methylene chloride/pentane mixture, and finally with methanol/pentane.
The Nn compound concentrated and adsorbed on the silica gel was eluted by passing a methylene chloride (15/as: v/v ratio) mixture. The solvent in the eluate was evaporated to obtain a Nn compound concentrate (viscous at room temperature).

Nn concentrate from UR oil (referred to as UR-Nn, 0onc) Nn content: 1.22 wt%, Wb content e, 1 ppm
below.

Sulfur content: 6.5! Nn0 from 7wt% HF oil! Thin (H'F-Nn, 0o
nc) Nn minutes: 2.16wt96. Nb minute:
1 ppm or less.

Sulfur content: 4.62 wt Both concentrates were added to the highly refined mineral oil (OA oil) shown in Table 1 to obtain a sample oil, and the oxidation stability was measured. The results are shown in Table 2.

Table 2 Determine the time required for the oxygen pressure to drop by 30 μHgt-.

By incorporating the Nn concentrate, the values of oxidation stability and oxygen absorption test were significantly improved.

Example 2 The HF-Nn and Cone described in Example 1 were replaced with alkylbenzene (Pansorp H-L manufactured by Mitsubishi Yuka), alkylnaphthalene (manufactured by Kureha Chemical Co., Ltd. 5-4oo), and the alkylbenzene described in Example 1. The mixture of OA oil used in (50
(near 0 V/V ratio) and a commercially available electrical insulating oil (alkylbenzene-mineral oil type, Nnt 8 ppm) to examine oxidation stability. The results are shown in Table 3.

As assigned in Table 5, Example 1 and Example 2, the two improvers of the present invention have an extremely excellent effect of improving oxidation stability.

Patent applicant: Japan Mining Co., Ltd. Agent: Patent attorney (7569) Keishi Namikawa

Claims (3)

[Claims] (1) An oxidation stability improver for lubricating oil, characterized in that its main constituent is a non-basic nitrogen compound concentrated and separated from mineral oil. (2) The oxidation stability improver 8 for lubricating oils described in the preceding paragraph, in which the non-basic nitrogen content is limited to 1/20 or less by weight of the non-basic nitrogen content. (3) The non-basic nitrogen content in the lubricating oil can be reduced to 16 p by blending the concentrate, whose main constituent is non-basic nitrogen compounds concentrated and separated from mineral oil, into the purified lubricating oil.
A method for improving the oxidation stability of a lubricating oil, characterized by reducing the amount of basic nitrogen to 3 ppm or more and 3 ppm or more.