JPH0317165B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved electrical insulating oil comprising an alkylnaphthalene and an aromatic bicyclic olefin. More specifically, oil-impregnated electrical equipment having a metal conductor or metal electrode and an insulator or dielectric made of insulating paper and/or plastic such as polyolefin, such as an oil-impregnated capacitor;
This invention relates to electrical insulating oil suitable for impregnating oil-impregnated cables and the like. In recent years, demands have increased for oil-impregnated electrical equipment such as oil-impregnated capacitors, oil-impregnated cables, and transformers for higher voltage, longer life, and smaller size. Improvements have been made. In other words, from the perspective of insulating materials and dielectric materials,
Plastics such as polyolefins such as polypropylene, polyester, polyvinylidene fluoride resin, and polycarbonate are used, which have better dielectric strength than conventional insulating paper. Its usage is also
For example, in oil-impregnated capacitors, insulating paper and these plastic films may be used in combination, or these plastic films may be used alone. Capacitors using metallized paper or metallized plastic film are also used, in which the metal electrode is a metal layer deposited on the paper or plastic film. In addition, in oil-impregnated cables, the insulator is made of crosslinked or uncrosslinked polyethylene, stretched or unstretched polypropylene, polyolefin such as polymethylpentene, polyester, polyvinylidene fluoride resin, polycarbonate, or other plastic film instead of insulating paper. Single or composite films of these plastic films and insulating paper have been developed. Examples of this composite film include a film in which plastic is laminated on insulating paper by melt extrusion or thermocompression bonding, and a composite film in which insulating paper and silane-grafted polyethylene are cross-linked in the presence of a silanol condensation catalyst. There are also mixed papers made from paper pulp and plastic fibers such as polyolefin. On the other hand, in terms of impregnating oils, in addition to conventional mineral oils, polybutenes, alkylbenzenes, etc., various synthetic electrical insulating oils have been developed. Alkylnaphthalenes such as diisopropylnaphthalene are also one of them. However, alkylnaphthalenes cannot necessarily satisfy the demands for smaller size, higher voltage, and longer life of oil-impregnated electrical equipment. In view of the above circumstances, the present inventors have completed the present invention as a result of intensive research into electrical insulating oil from the perspective of impregnating oil. That is, the present invention provides (a) one of alkylnaphthalenes.
species or two or more species and (b) one or two olefins having two fused or non-fused aromatic rings.
This invention relates to electrical insulating oil consisting of more than one species.
The alkyl group in the alkylnaphthalene in item (a) above is methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl,
These include tert-butyl and amyl groups, and the number may be plural, but alkylnaphthalenes in which the total number of carbon atoms in the alkyl group is 1 to 10 are preferred. Further, these alkylnaphthalenes can be used alone or as a mixture of two or more, and those having a viscosity of 10 cSt or less at 40°C are preferable for use as a component of the electrical insulating oil of the present invention. . Particularly preferred is diisopropylnaphthalene. The above alkylnaphthalene can be obtained by alkylating naphthalene with propylene, propyl chloride, butene, etc. The compound used in combination with the alkylnaphthalene in item (a) above is an olefin having two fused or non-fused aromatic rings as in item (b). This olefin has
There are cyclic olefin derivatives such as cyclopentene and cyclohexene, and chain olefin derivatives.
For example, such olefins include compounds represented by the following general formulas () to (). general formula Here, R ₁ is an alkenylene group or a cycloalkenylene group having one unsaturated double bond. Further, m and n are integers from 0 to 3, m R ₂ and n R ₃ are the same or different, and are hydrogen atoms or alkyl groups. general formula Here, R ₄ is an alkenyl group or a cycloalkenyl group, and R ₅ is an alkylene group or a cycloalkylene group. Further, m and n are integers from 0 to 3, m R ₂ and n R ₃ are the same or different, and are hydrogen atoms or alkyl groups. general formula Here, R ₄ is an alkenyl group or a cycloalkenyl group. Further, m and n are integers from 0 to 3, m R ₂ and n R ₃ are the same or different, and are hydrogen atoms or alkyl groups. general formula Here, R ₄ is an alkenyl group or a cycloalkenyl group. Further, m and n are integers from 0 to 3, m R ₂ and n R ₃ are the same or different, and are hydrogen atoms or alkyl groups. The alkenylene group or cycloalkenylene group of R ₁ in the above formula () is 2 from ethylene, propylene, butene, isobutene, pentene, methylpentene, hexene, cyclopentene, cyclohexene, alkylcyclohexene, etc.
It is a divalent substituent excluding hydrogen atoms, and the alkyl groups R ₂ and R ₃ are methyl, ethyl,
These include propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, and amyl groups. Specific compounds of formula () include stilbene, 4-methylstilbene, 1,2-diphenylpropene, 1,3-diphenylpropene, 1,4
-diphenylbutene-1, 1,4-diphenylbutene-2, 1,1-diphenylethylene, 1-phenyl-1-(4-ethylphenyl)ethylene,
1,1-diphenylpropene-1,2,3-diphenylpropene, 1,2-diphenylbutene-
Examples include 2,1,3-diphenylbutene-1, 2,4-diphenyl-4-methylpentene-1, 1,2-diphenylcyclohexene, and phenylbenzylcyclohexene. These can be produced by acid-catalyzed dimerization or co-dimerization of styrene or styrenes such as α-methylstyrene and vinyltoluene. Furthermore, 1,2-diphenylethylene and the like may be dehydrated by reacting benzaldehyde with benzylmagnesium bromide, and the same can be applied to 1,2-diphenylpropene. Furthermore, 1,1-diphenylethylene can be obtained by reacting diphenyl ketone with a Grignard reagent such as methylmagnesium iodide and dehydrating it. R ₄ in the compound of formula () is an alkenyl group or cycloalkenyl group such as vinyl, propenyl, isopropenyl, allyl, butenyl, cyclopentenyl, cyclohexenyl, and R ₅ is a linear saturated aliphatic hydrocarbon or cyclopentane,
It is a divalent substituent obtained by removing two hydrogen atoms from a saturated alicyclic hydrocarbon such as cyclohexane or cycloheptane. In addition, R ₂ and
R ₃ is the same as R ₂ and R ₃ in formula (). Specific compounds of formula () include 1-phenyl-1-(4-vinylphenyl)ethane, 1-
(4-methylphenyl-1-(4-vinylphenyl)ethane, 1-phenyl-1-(4-isopropenylphenyl)ethane, phenyl-(4-vinylphenyl)methane, phenyl-(cyclohexenylphenyl)methane, etc. These can be synthesized by various synthetic chemical methods.For example, phenyl-(vinylphenyl)ethane is produced by reacting diphenylethane with acetyl chloride using a Friedel-Crafts catalyst to obtain phenyl-(acetylphenyl)ethane. , and then reduced with sodium borohydride etc. and then dehydrated. Phenyl-(isopropenyl phenyl) ethane etc. are obtained by reacting phenyl-(formylphenyl) ethane with a Grignard reagent such as methylmagnesium iodide, and then It can be obtained by dehydration.Alkenyl group or cycloalkenyl group R ₄ in formula () can be obtained by dehydration.
It is the same as R ₄ , and R ₂ and R ₃ as alkyl groups are also the same as R ₂ and R ₃ in formula (). Specific compounds of the formula () include 2-isopropenylbiphenyl, 4-isopropenylbiphenyl, 2-isopropenyl-4'-isopropylbiphenyl, cyclohexenylbiphenyl, and cyclopentenylbiphenyl. Among these, for example, isopropenylbiphenyl can be obtained by dehydrogenating isopropylbiphenyl. Furthermore, R ₄ as an alkenyl group or cycloalkenyl group in formula () is also the same as R 4 in formula (), and R ₄ as an alkyl group
R ₂ and R ₃ are also the same as R ₂ and R ₃ in formula (). Specific compounds of this formula () include α-vinylnaphthalene, isopropenylnaphthalene, allylnaphthalene, and 1-cyclopent-2-enylnaphthalene. Among these, for example, vinylnaphthalene can be obtained by reacting formylnaphthalene with a Grignard reagent such as methylmagnesium iodide and then dehydrating it. The aromatic olefins represented by the above formulas () to () are used by being mixed and dissolved with an alkylnaphthalene, and it is sufficient if the mixture becomes liquid at room temperature after being mixed and dissolved. Therefore, it may be either liquid or solid at room temperature. Further, this olefin having two fused or non-fused aromatic rings can be used alone or in combination with the alkylnaphthalene as a mixture of two or more. In the present invention, an electrical insulating oil is obtained by mixing the alkylnaphthalene (a) with the aromatic olefin (b) as described above. Viscosity is 30cSt at 40℃
The following is preferable, more preferably 10 cSt. Therefore, if the compounds represented by formulas () are appropriately selected and used as the alkylnaphthalene (a) and the aromatic olefin (b) so that the viscosity after mixing falls within this range, good. Alkylnaphthalene itself is biodegradable, heat resistant,
It has excellent oxidation stability, electrical properties, and hydrogen gas absorption, but when used in combination with the aromatic olefin of the present invention, the hydrogen gas absorption is further improved, and it is similar to aromatic olefin. Despite the combined use of unsaturated compounds, no deterioration in biodegradability, thermal stability, or oxidative stability was observed, and other electrical properties were further improved. Although the mixing ratio of the alkylnaphthalene (a) and the aromatic olefin (b) is arbitrary, it is preferable that the latter aromatic olefin be in the range of 0.01 to 50% by weight with respect to the total amount of both to achieve a synergistic effect. It is preferable from the point of view. More preferably, it is in the range of 1.0 to 3.0% by weight. The electrical insulating oil of the present invention consists of a mixture having the above composition, but is not limited thereto. That is, in order to improve the desired electrical performance without impairing the general electrical performance, conventionally known electrical insulating oils such as polybutene, mineral oil,
Alkylbenzene, diarylalkane, alkylbiphenyl, etc. can be added and used. Generally, adding polybutene improves fixed volume resistivity and dielectric loss tangent, mineral oil improves dielectric breakdown voltage, and other aromatic insulating oils such as alkylbenzene improve dielectric breakdown voltage, dielectric loss tangent, pour point, etc. tends to improve In addition, antioxidants known as electrical insulating oils,
For example, as a phenolic type, 2,6-di-tert-butyl-p-cresol (trade name: BHT),
2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-butylidenebis(3
-methyl-6-tert-butylphenol), 4,
4'-thiobis(3-methyl-6-tert-butylphenol), stearyl-β-(3,5-di-tert-butyl-4-hydroxyphenol)propionate (trade name: Irganox 1076), tetrakis[methylene- 3(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane (trade name:
Irganox 1010), 1,3,5-trimethyl-2,
4,6-tris(3,5-di-tert-butyl-4-
Bidroxybenzyl)benzene (Product name: Ionox)
330), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenol)butane (trade name: Topanol CA), and sulfur-based compounds such as dilaurylthiodipropionate and distearylthio. Dipropionate, lauryl stearyl thiodipropionate, dimyristyl thiodipropionate, etc., and phosphorus types such as triisodecyl phosphite, diphenyl isodecyl phosphite, triphenyl phosphite, trinonyl phenyl phosphite, etc. can be added to the electrical insulating oil of the present invention. These antioxidants can be used individually or in combination of two or more, and the amount added is 0.001 to 5% by weight, more preferably 0.01 to 2.0% by weight based on the insulating oil.
Weight%. Further, phosphoric acid ester compounds, epoxy compounds, etc., which are known as additives for electrical insulating oils, may be used in combination for the purpose of imparting flame retardancy and other purposes. The electrical insulating oil of the present invention is suitable as a general electrical insulating oil, and is particularly suitable for impregnating oil-impregnated electrical equipment such as capacitors, cables, and transformers. Note that the structures of these devices are as already described. That is, by impregnating the electrical insulating oil of the present invention, higher pressure, smaller size, and longer life of oil-impregnated electrical equipment can be achieved. Furthermore, by impregnating an insulating oil consisting of multiple components, as a result of the synergistic effect between the components,
It is possible to improve the above properties, maintain the excellent electrical properties, biodegradability, heat resistance, and oxidation stability of each component itself, and adjust the viscosity and pour point to a suitable range. The structure of the oil-impregnated electrical equipment can be efficiently and easily carried out, and the oil-impregnated electrical equipment can be obtained that exhibits high performance without being restricted by usage conditions. Next, the present invention will be explained in detail with reference to Examples and Comparative Examples. Examples and Comparative Examples The insulating oils used in the Examples and Comparative Examples are summarized in Table 1. In Table 1, insulating oils No. 1 and No. 19 are used as comparative examples. In both tests, 0.2% by weight of BHT was added as an antioxidant to the insulating oil.
In addition, the viscosity of all insulating oils is 4.5 to 4.5 at 40℃.
It was 6.5 cSt. (Test using an oil-impregnated capacitor) A polypropylene film with a thickness of 28μ and a width of 62mm was used as the dielectric material, and an insulating paper with a thickness of 12μ and a width of 62mm was used as the electrode.
A model capacitor was fabricated using aluminum foil with a width of 50 mm, which was wound and laminated according to a conventional method. This capacitor was impregnated with various insulating oils under vacuum to create an oil-impregnated capacitor with a capacitance of approximately 0.7 μF. Next, a voltage was applied to these capacitors, and the corona discharge onset voltage (CSV) and corona discharge extinction voltage (CEV) were measured. The measurement temperature is 30°C. The measurement results are shown in Table 2. Separately, a constant alternating current voltage was applied to an oil-impregnated capacitor prepared in the same manner, and the life of the capacitor was determined by measuring the time until the capacitor broke down. Table 2 shows the average value of the breakdown times of the remaining five capacitors after excluding the maximum and minimum values from among the breakdown times of seven capacitors impregnated with the same insulating oil. Note that the numerical values in the table indicate relative values. That is, the breakdown time is shown assuming that the base insulating oil is 100% alkylnaphthalene.

【table】

【table】

[Table] From the results in Table 2, it is clear that the capacitor impregnated with the electrical insulating oil of the present invention has high CSV and CEV, and its life span is significantly improved. Moreover, the composition containing the aromatic olefin of the present invention is far superior to the composition containing the aliphatic olefin. As explained above, the electrical insulating oil of the present invention is an electrical insulating oil with excellent stability against discharge energy, and is suitable for impregnating oil-impregnated electrical equipment.

Claims (1)

[Claims] 1. Electrical insulating oil comprising (a) one or more alkylnaphthalenes, and (b) one or more olefins having two fused or non-fused aromatic rings. . 2. The electrical insulating oil according to claim 1, wherein the alkylnaphthalene is diisopropylnaphthalene. 3. The electrical insulating oil according to claim 1 or 2, wherein the electrical insulating oil contains 0.001 to 5% by weight of an antioxidant.