JP2002367431A - Insulating oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulating oil composition having sufficiently high impulse breakdown voltage, and capable of obtaining sufficient resistance to thunderbolt, when used by being filled in a high-voltage apparatus arranged outdoors. SOLUTION: This insulating oil composition includes at least one kind of base oil, selected from among a group composed of mineral oil and synthetic oil and 1 to 2 nitrogen atoms as a heterocyclic constitutive atom, and includes a nitrogen containing heterocyclic compound being a single bond in both bonds of the nitrogen atom and the other atom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electric insulating oil composition, and more particularly, to an electric insulating oil composition having a high impact breakdown voltage.

[0002]

2. Description of the Related Art Conventionally, high-voltage equipment such as a transformer, a high-voltage cable, a high-voltage circuit breaker, and a condenser is installed in a power plant, a factory, a large-scale facility, and the like. Since these high-voltage devices are often installed outdoors, lightning strikes are required.

As a countermeasure against lightning strikes, there are many cases where devices such as lightning rods or the like are devised. However, design changes are being considered so that the high-voltage equipment itself has sufficient resistance to lightning strikes.

[0004]

As a method of improving the resistance of high-voltage equipment to lightning strikes, there is a method of improving the performance of electric insulating oil used for filling high-voltage equipment. For example,
According to the ASTM D3487 standard, a desirable impact breakdown voltage as an electrical insulating oil is set to 145 kV or more.
In many cases, the voltage is less than 50 kV, which is not always sufficient as the electrical insulating oil for the above-mentioned high-voltage equipment.

[0005] In the conventional electric insulating oil, the impact breakdown voltage is generally improved by selecting a specific base oil or performing a sufficient refining treatment. Relatively expensive base oils such as base oils and highly refined mineral oils such as hydrocracked mineral oils are often used. However, simply improving the properties of the base oil itself as described above may not be enough, and it is very difficult to obtain a sufficient impact breakdown voltage when using a cheaper low-grade refined mineral oil. there were.

The present invention has been made in view of the above-mentioned problems of the prior art, and has a sufficiently high impact breakdown voltage, and has a sufficient resistance to lightning strike when used for charging high-voltage equipment installed outdoors. It is an object of the present invention to provide an electric insulating oil composition capable of obtaining the following.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that a nitrogen-containing complex having a specific structure in a mineral oil and / or a synthetic oil as a base oil. The inventors have found that the above problems can be solved when a cyclic compound is added, and have completed the present invention.

That is, the electric insulating oil composition of the present invention comprises:
At least one base oil selected from the group consisting of mineral oils and synthetic oils, and contains 1 to 2 nitrogen atoms as a heterocyclic ring-constituting atom, and the bond between the nitrogen atom and another atom is a single bond. And a nitrogen-containing heterocyclic compound.

In the electric insulating oil composition of the present invention, the base oil and the nitrogen-containing heterocyclic compound are blended to obtain an impact breakdown voltage inherently exhibited by the base oil and a nitrogen-containing heterocyclic compound. A sufficiently high impact breakdown voltage is achieved by a synergistic effect with the effect of improving the impact breakdown voltage by the addition of Nb. Therefore, when the electrical insulating oil composition of the present invention is used in a high-voltage device installed outdoors, sufficient resistance to lightning strikes can be obtained.

In the present invention, the content of the nitrogen-containing heterocyclic compound is preferably 5 to 500 ppm by mass based on the total amount of the composition. When the content of the nitrogen-containing heterocyclic compound is within the above range, in addition to the higher impact breakdown voltage, excellent electric insulation such as a small dielectric loss tangent and a high volume resistivity is achieved. Tend to be.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail.

The electrical insulating oil of the present invention contains at least one of mineral oil and synthetic oil as a base oil. The base oil is not particularly limited, and a mineral base oil, a synthetic base oil, or the like, which is known as a base oil of an electric insulating oil or another lubricating oil, can be used.

As the mineral base oil used in the present invention, specifically, a lubricating oil fraction obtained by subjecting a crude oil to atmospheric distillation and vacuum distillation is subjected to solvent removal, solvent extraction, and hydrocracking. Paraffinic mineral oil, naphthenic mineral oil, etc., which are refined by appropriately combining refining treatments such as solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing and clay treatment.

The synthetic base oil used in the present invention includes, specifically, poly-α-olefin, (polybutene, 1-octene oligomer, 1-decene oligomer, etc.), polybutene, alkylbenzene, alkylnaphthalene, alkyl Hydrocarbon synthetic oils such as diphenylalkane (alkyldiphenylethane, alkylphenylxylylethane, benzyltoluene, etc.) and alkylbiphenyl; diesters (ditridecyl glutarate,
Di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sepacate, etc., polyol esters (trimethylolpropane caprylate, trimethylolpropane velargonate, pentaerythritol 2-ethylhexanoate, menthaerythritol Largonate),
Oxygen-containing synthetic oils such as polyoxyalkylene glycol and polyphenyl ether; silicone oils and perfluoroalkyl ethers.

In the present invention, one of the above base oils may be used alone, or two or more may be used in combination at an arbitrary mixing ratio. The viscosity of the base oil according to the present invention is arbitrary, but the kinematic viscosity at 40 ° C. is 1 to 3.
It is preferably from 50mm ² / s, 3~40mm ² /
s, more preferably 5 to 30 mm ² / s.

Of the above base oils, highly refined mineral oils such as hydrocracked mineral oils and hydrocarbon-based synthetic oils themselves exhibit relatively high impact breakdown voltages. Is preferred because the synergistic effect of the impact breakdown voltage inherently possessed and the effect of improving the impact breakdown voltage by the addition of the nitrogen-containing heterocyclic compound described below can provide an electrical insulating oil composition exhibiting a higher impact breakdown voltage. . Also,
Low-grade refined mineral oils such as solvent-refined mineral oils exhibit relatively low impact breakdown voltages themselves. However, since the effect of adding a nitrogen-containing heterocyclic compound described later has a greater effect of improving the impact breakdown voltage, these base oils It is preferable to use an epoxy resin, since an electrical insulating oil composition having a higher impact breakdown voltage can be obtained. These base oils have a dielectric loss tangent, volume resistivity, oxidation stability,
It can be appropriately selected according to various required performances such as hydrogen gas absorption.

In the present invention, the above-described base oil contains one or two nitrogen atoms as heterocyclic constituent atoms, and the bond between the nitrogen atom and any other atom is a single bond. Formula compounds are formulated.

In the nitrogen-containing heterocyclic compound according to the present invention, the bond between the nitrogen atom constituting the heterocyclic ring and the other atom is a single bond, and the double bond may be present in the heterocyclic ring. However, the nitrogen atom does not participate in the double bond. If a compound in which a nitrogen atom as a heterocyclic ring-constituting atom is bonded to another atom by a double bond is added to the base oil, a sufficient effect of improving the impact breakdown voltage cannot be obtained, and
The oxidation stability of the electrical insulating oil composition becomes insufficient.

Such a nitrogen-containing heterocyclic ring may be composed of a carbon atom and a nitrogen atom, and may contain other atoms such as an oxygen atom and a sulfur atom in addition to the carbon atom and the nitrogen atom. It may be configured. Among these, it is preferable to use a nitrogen-containing heterocyclic compound having a heterocyclic ring composed of a carbon atom and a nitrogen atom, since the impact breakdown voltage is further increased and excellent oxidation stability tends to be obtained.

Further, as described above, the heterocyclic ring contains one or two nitrogen atoms as a heterocyclic ring constituting atom. When the heterocyclic ring does not contain a nitrogen atom as a ring-constituting atom, or when the heterocyclic ring contains three or more nitrogen atoms as a heterocyclic-constituting atom, the effect of improving the impact breakdown voltage becomes insufficient. Here, the number of nitrogen atoms refers to the total number of all nitrogen atoms contained in the heterocyclic ring of the nitrogen-containing heterocyclic compound, and the nitrogen-containing heterocyclic compound has a plurality of monocyclic heterocycles or polycyclic heterocycles. When it has a cyclic heterocycle, it refers to the total number of nitrogen atoms contained in those heterocycles.

The heterocyclic ring of the nitrogen-containing heterocyclic compound according to the present invention may be either monocyclic or polycyclic as long as it contains one or two nitrogen atoms as a heterocyclic constituent atom. Often, when the heterocycle is a polycyclic fused ring,
Any of non-condensed rings may be used, but it is preferable that the heterocyclic ring is a condensed polycyclic ring composed of two to three rings because the effect of improving the impact breakdown voltage tends to be further enhanced. Further, the heterocyclic ring may have aromaticity or may not have aromaticity.

Specific examples of such a heterocyclic ring include:
Indolizine ring, isoindole ring, indole ring, 4
Examples thereof include an H-quinolidine ring, a carbazole ring, an indoline ring, and an isoindoline ring. Among them, the use of a nitrogen-containing heterocyclic compound having an indole ring or a carbazole ring is preferable because the impact breakdown voltage can be further increased.

In the above heterocyclic ring, part or all of the hydrogen atoms bonded to the heterocyclic ring-constituting atoms may be substituted with a hydrocarbon group. Specific examples of such a hydrocarbon group include an alkyl group, an alkenyl group, a cycloalkyl group, an alkylcycloalkyl group, an aryl group, an alkylaryl group, and an arylalkyl group. Among them, an alkyl group is preferable. When the substituent is an alkyl group,
The impact breakdown voltage tends to be further increased, and excellent oxidation stability tends to be obtained.

Although the number of hydrocarbon groups in the heterocycle is not particularly limited, it is preferable that the number of hydrocarbon groups is one or two in order to further increase the effect of improving the impact breakdown voltage. Furthermore, the total carbon number of the hydrocarbon group is usually 1
From 20 in terms of the effect of improving the impact breakdown voltage.
6, preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and particularly preferably 1 to 4.

Preferred examples of the nitrogen-containing heterocyclic compound according to the present invention include indolizine represented by the following formula (1), isoindole represented by the following formula (2), and isoindole represented by the following formula (3) Indole, 4H-quinolidine represented by the following formula (4), carbazole represented by the following formula (5), indoline represented by the following formula (6), and the following formula (7)
And those in which a hydrogen atom bonded to a heterocyclic member of these compounds is substituted with a hydrocarbon group.

[0026]

Embedded image

[0027]

Embedded image

[0028]

Embedded image

[0029]

Embedded image

[0030]

Embedded image

[0031]

Embedded image

[0032]

Embedded image

The content of the nitrogen-containing heterocyclic compound according to the present invention is not particularly limited as long as the impact breakdown voltage of the electric insulating oil composition is not impaired, but is 5 ppm by mass or more based on the total amount of the electric insulating oil composition. And preferably 10
More preferably at least 30 ppm by mass.
pm or more. When the content of the nitrogen-containing heterocyclic compound is less than the lower limit, the effect of improving the impact breakdown voltage tends to be insufficient. Further, the content of the nitrogen-containing heterocyclic compound is preferably 500 mass ppm or less, more preferably 400 mass ppm or less, based on the total amount of the electric insulating oil composition,
More preferably, it is at most 300 ppm by mass,
Even more preferably, it is 0 mass ppm or less,
It is particularly preferred that the content be 0 ppm by mass or less. Even if the content of the nitrogen-containing heterocyclic compound exceeds the above upper limit, the effect of improving the impact breakdown voltage corresponding to the content is not seen, and conversely, the dielectric loss tangent (tan δ) increases and the volume resistivity decreases. Phenomena such as rubbing tend to occur, and electrical insulation tends to decrease.

The electric insulating oil composition of the present invention contains the above-mentioned base oil and nitrogen-containing heterocyclic compound, but may contain additives known for insulating oil. Specific examples of such additives include fluid antistatic agents such as benzotriazole; phenols such as 2,6-di-t-butyl-4-methylphenol (DBPC) and 2,6-di-t-butylphenol. Antioxidants; amine antioxidants such as phenylnaphthylamine; condensates of chlorinated paraffins and naphthalene; pour point depressants such as polymethacrylates and olefin polymers (including ethylene-propylene copolymers and alkylated polystyrene) And the like. The content of these additives is not particularly limited as long as the impact breakdown voltage of the electric insulating oil composition is not impaired, but the total content is preferably 5% by mass or less based on the total amount of the electric insulating oil. It is more preferably at most 0.1 mass%, more preferably at most 0.1 mass%.

The kinematic viscosity of the electric insulating oil composition of the present invention is not particularly limited, but the kinematic viscosity at 40 ° C. is 1 to 50 mm.
Is preferably ² / s, more preferably 3~40mm ² / s, and further preferably from 5 to 30 mm ² / s.

In the conventional electric insulating oil, it is considered that it is desirable that the nitrogen content (basic nitrogen and non-basic nitrogen) contained in the electric insulating oil is small from the viewpoint of oxidation stability. As the base oil, those obtained by performing purification treatments such as hydrogenation purification, solvent extraction purification, solid adsorption purification, and sulfuric acid washing purification alone or in combination of two or more kinds are often used.

The electrical insulating oil composition of the present invention also preferably contains as little basic nitrogen as possible from the viewpoint of oxidation stability. Specifically, the basic nitrogen content in the electrical insulating oil composition is preferably It is preferably at most 3 ppm. Here, the basic nitrogen content refers to UO of UOP of the United States.
P Method 269-90 "NITROGENB
ASES IN HYDROCARBONS BY P
OTENTIONOMETRIC TITRATION "
(1990) [p
pm].

The nitrogen-containing heterocyclic compound contained in the electric insulating oil composition of the present invention corresponds to a non-basic nitrogen component, and the nitrogen-containing heterocyclic compound is oxidatively stable in the electric insulating oil composition. It is possible to improve the impact breakdown voltage without impairing the properties, and an increase in the nitrogen content due to the incorporation of the nitrogen-containing heterocyclic compound does not significantly affect the oxidation stability. However, in the present invention, not only the oxidation stability is improved, but also the dielectric loss tangent is reduced, the volume resistivity is increased, and the like. It is preferably at most 30 ppm, more preferably at most 30 ppm.
pm or less, still more preferably 15 ppm or less, particularly preferably 10 ppm or less. Here, the non-basic nitrogen content is a value obtained by subtracting the above basic nitrogen content from the nitrogen content measured by the method specified in JIS K 2609 “Test method for crude oil and petroleum product nitrogen content” [ ppm].

With the electric insulating oil composition of the present invention having the above-described structure, a high impact breakdown voltage which is difficult to achieve with the conventional electric insulating oil is realized. Therefore, the electric insulating oil composition of the present invention, when used in a high-voltage equipment such as a power plant, a factory, a transformer installed outdoors in a large-scale facility, a high-voltage cable, a high-voltage circuit breaker, and a condenser, This is very useful in that it provides sufficient resistance to lightning strikes.

[0040]

EXAMPLES Hereinafter, the present invention will be described more specifically based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Examples 1 to 4 and Comparative Examples 1 to 5 (Preparation of Sample Oils) In Examples 1 to 4 and Comparative Examples 1 to 4, the following base oils and nitrogen-containing compounds were prepared according to the composition shown in Table 1. A sample oil was prepared by mixing as follows. In Comparative Example 5, the base oil 1 was used as a sample oil. 4 of the obtained sample oil
Table 1 shows the kinematic viscosity, basic nitrogen content and non-basic nitrogen content at 0 ° C.

Base oil 1: Paraffin solvent refined mineral oil (40
Kinematic viscosity at ℃: 6.3 mm ² / s) Nitrogen-containing compound 1: carbazole Nitrogen-containing compound 2: N-methylcarbazole Nitrogen-containing compound 3: Quinoline Nitrogen-containing compound 4: benzotriazole.

(Measurement of Impact Breakdown Voltage) For each sample oil of Examples 1-4 and Comparative Examples 1-5, ASTM D330
An impact breakdown voltage test defined as 0 was performed. Table 1 shows the obtained impact breakdown voltage values.

(Oxidation stability test) Each sample oil of Examples 1-4 and Comparative Examples 1-5 was subjected to JIS C 2101.
"Oxidation stability test" of "Electric insulating oil test method" was performed. Table 1 shows the total acid value of the sample oil before and after the test.

[0045]

[Table 1]

Examples 5 to 8 and Comparative Example 6 In Examples 5 to 8, naphthenic solvent refined mineral oil (4
A kinematic viscosity at 0 ° C .: 8.0 mm ² / s, hereinafter referred to as “base oil 2”) and nitrogen-containing compounds 1 and 2 were mixed so as to have the composition shown in Table 2, to prepare a sample oil. In Comparative Example 6, the base oil 2 was used as a sample oil. 40 ° C of the obtained sample oil
Table 2 shows the kinematic viscosity, basic nitrogen content and non-basic nitrogen content in

Further, with respect to the sample oils of Examples 5 to 8 and Comparative Example 6, an impact breakdown voltage test and an oxidation stability test were performed in the same manner as in Example 1. Table 2 shows the obtained results.

[0048]

[Table 2]

Examples 9 to 12 and Comparative Example 7 In Examples 9 to 12, a mixture of base oil 1 and alkylbenzene (kinematic viscosity at 40 ° C .: 12.8 mm ² / s) (mass ratio: 50/50; Kinematic viscosity at 40 ° C .:
7.1 mm ² / s, hereinafter referred to as “base oil 3”) and nitrogen-containing compounds 1 and 2 were mixed to obtain the composition shown in Table 3 to prepare a sample oil. In Comparative Example 7, the base oil 3 was used as a sample oil. Table 3 shows the kinematic viscosity at 40 ° C., the basic nitrogen content, and the non-basic nitrogen content of the obtained sample oil.

The sample oils of Examples 9 to 12 and Comparative Example 7 were subjected to an impact breakdown voltage test and an oxidation stability test in the same manner as in Example 1. Table 3 shows the obtained results.

[0051]

[Table 3]

As is clear from the results shown in Tables 1 to 3, in the sample oils of Examples 1 to 12, Comparative Examples 5 to 7 were used.
(That is, base oils 1 to 3) show a sufficiently high impact breakdown voltage value, and the addition of nitrogen-containing compounds 1 and 2 corresponding to the nitrogen-containing heterocyclic compound according to the present invention improves the impact breakdown voltage. The effect was recognized. It was also confirmed that these sample oils had excellent oxidation stability.

On the other hand, Comparative Examples 1 and 2 using the nitrogen-containing compound 3 in which the nitrogen atom of the heterocycle participates in the double bond.
In the case of the sample oils of Comparative Examples 3 and 4 in which the nitrogen-containing compound 4 containing three nitrogen atoms in the heterocycle was used, the effect of improving the impact breakdown voltage by the compounding of the nitrogen-containing compound was insufficient. Was.

[0054]

As described above, the electric insulating oil composition of the present invention realizes a high impact breakdown voltage which was difficult to achieve with the conventional electric insulating oil. Therefore, the electrical insulating oil composition of the present invention is very useful as an electrical insulating oil for high-voltage equipment such as a transformer, a high-voltage cable, a high-voltage circuit breaker, and a condenser installed outdoors in a power plant or the like.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C10N 30:00 C10N 30:00 Z 40:16 40:16 F term (Reference) 4H104 BE26C BE27C BE29C DA02A EB02 LA20 PA12 4J002 AE051 BB161 BB171 EU026 EU066 EU096 FD070 FD100 GQ01 5G305 AA03 AB02 BA05 CA60 CB05 CB15 CD09 CD11

Claims (2)

[Claims] Claims: 1. At least one base oil selected from the group consisting of mineral oil and synthetic oil, and containing one or two nitrogen atoms as a heterocyclic-constituting atom, wherein the bond between the nitrogen atom and another atom is And a nitrogen-containing heterocyclic compound which is also a single bond. 2. The content of the nitrogen-containing heterocyclic compound is as follows:
The electrical insulating oil composition according to claim 1, wherein the composition is 5 to 500 ppm by mass based on the total amount of the composition.