JPH0317328B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel electrical insulating oil comprising an aromatic two-ring ether and an aromatic two-ring olefin. More specifically, a metal conductor or metal electrode,
Aromatic two-ring ether suitable for impregnating oil-impregnated electrical equipment, such as oil-impregnated capacitors and oil-impregnated cables, which have at least a portion thereof an insulator or dielectric made of a plastic material such as polyolefin. The present invention relates to a novel electrical insulating oil consisting of an aromatic bicyclic olefin and an aromatic bicyclic olefin. In recent years, as oil-impregnated electrical equipment such as oil-impregnated capacitors, oil-impregnated cables, and transformers have become higher in voltage, longer in life, and smaller in size, various plastic materials have come to be used in conjunction with traditional insulating paper.
These plastic materials used as constituent materials for oil-impregnated electrical equipment are likely to be used more and more in the future, and products in which all conventional insulating paper is replaced with plastic materials have already begun to be used. However, conventional electrical insulating oils, such as refined mineral oils, polybutenes, alkylbenzenes, or chlorinated biphenyls, have various drawbacks. For example, chlorinated biphenyls are avoided due to the pollution problems inherent to halogenated aromatic compounds. In addition, various conventional electrical insulating oils are
Compatibility with plastic materials such as polyolefins used in the oil-impregnated electrical equipment mentioned above is not always satisfactory. That is, when conventional electrical insulating oils come into contact with these plastic materials, they can dissolve or swell the plastic materials, reducing their dielectric strength. Therefore, there is a strong need for a high-performance electrical insulating oil that can better meet the demands for higher voltage and smaller size of oil-impregnated electrical equipment. In view of the above circumstances, the present inventors conducted intensive research and found that by blending an aromatic two-ring olefin with an aromatic two-ring ether, an electrical insulating oil with significantly superior properties was obtained. The present invention was completed by discovering that That is, the present invention provides (a) an aromatic ether having two at least one kind of fused or non-fused aromatic rings, and (b) an aromatic ether having two at least one kind of fused or non-fused aromatic rings. This invention relates to an electrical insulating oil made of an aromatic olefin. The aromatic ether of the present invention is a non-halogen aromatic monoether having two fused or non-fused aromatic rings, and is a symmetric or asymmetric ether. Examples of the aromatic ether include diaryl ether, arylalkyl ether,
Examples include dialkyl ether. These aryl groups include phenyl, tolyl, xylyl, ethyl phenyl, propylphenyl, cumenyl, mesityl, butylphenyl, and the like. Furthermore, aralkyl groups include benzyl, α-methylbenzyl, phenylethyl, phenylpropyl, and the like. Specifically, diaryl ethers include phenyl tolyl ether, ditolyl ether, phenyl xylyl ether, phenyl cumenyl ether, phenyl sec-butyl phenyl ether, and phenyl tert-butyl phenyl ether. Further, examples of the arylalkyl ether include ethyl phenyl benzyl ether, propylphenyl benzyl ether, cumenyl benzyl ether, and phenyl phenylpropyl ether. Examples of the dialkyl ether include dibenzyl ether, bis(phenylethyl) ether, bis(α-methylbenzyl) ether, and benzyl phenylethyl ether. In addition to the above, examples of the aromatic ether as a component of the insulating oil of the present invention include alkoxy or cycloalkoxydiarylalkane, alkoxy or cycloalkoxydiaryl, alkoxy or cycloalkoxynaphthalene, and the like. The alkoxy or cycloalkoxy groups in these compounds include methoxy, ethoxy, propoxy, isopropoxy, putoxy, isopoxy, sec-butoxy, tert-butoxy,
A group such as cyclohexyloxy. Specifically, diarylalkane-based ethers include methoxydiphenylmethane, ethoxydiphenylmethane, methoxydiphenylethane, and propoxydiphenylethane. Examples of diaryl ethers include methoxybiphenyl,
Examples include ethoxybiphenyl, propoxydiphenyl, and isopropoxybiphenyl. Examples of naphthalene-based ethers include methoxynaphthalene, methoxy-ethylnaphthalene, ethoxynaphthalene, propoxynaphthalene, isopropoxynaphthalene, butoxynaphthalene, sec-butoxynaphthalene, and isobutoxynaphthalene. These aromatic ethers can be used alone or as a mixture of two or more, and among them, those with a viscosity at 40°C of 30 cSt or less, more preferably 10 cSt or less, are suitable for the electrical insulating oil of the present invention. Preferred for use as a component. Particularly preferred are ditolyl ether, bis(α-
methylbenzyl) ether, etc. The compound used in combination with the aromatic two-ring ether in item (a) is the olefin in item (b). This olefin is a non-halogen aromatic two-ring olefin having two fused or non-fused aromatic rings. Note that aromatic two-ring ether and aromatic two-ring olefin refer to compounds having two aromatic rings, and in the case of containing an aliphatic ring, the compound as a whole contains three or more rings. Also includes. These olefins include derivatives of cyclic olefins such as cyclopentene and cyclohexene, and derivatives of chain olefins, such as 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 a saturated alkylene group or a cycloalkylene group. Further, m and n are integers of 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 of 0 to 3, and m R ₂ and n R ₃ are the same or different, and each is a hydrogen atom or an alkyl group. general formula Here, R ₄ is an alkenyl group or a cycloalkenyl group. Further, m and n are integers of 0 to 3, and 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,
propyl, isopropyl, butyl, inbutyl,
It is an alkyl group such as sec-butyl, tert-butyl, amyl, etc. 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 phenyl-benzylcyclohexene. 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. R4 in the compound of formula () is an alkenyl group or cycloalkenyl group such as vinyl, propenyl, isopropenyl, allyl, butenyl, cyclopentenyl, cyclohexenyl, and _R5 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, R2, which is an alkyl group, and
The definition of R3 is the same as _R2 and _R3 in formula (). Specific compounds of formula () include 1-phenyl-1-(4-vinylphenyl)ethane, 1-(4
-methylphenyl)-1-(4-vinylphenyl)
These include ethane, 1-phenyl-1-(4-isopropenylphenyl)ethane, phenyl-(4-vinylphenyl)methane, and phenyl-(cyclohexenylphenyl)methane. 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, which is then reduced with sodium borohydride and then dehydrated. can be obtained. Phenylisopropenyl phenyl) ethane and the like can be obtained by reacting phenyl-(formylphenyl) ethane with a Grignard reagent such as methylmagnesium iodide, followed by dehydration. In addition, R ₄ , which is an alkenyl group or a cycloalkenyl group in formula (), is
It is the same as R ₁ , and R ₂ and R ₃ as alkyl groups are also the same as R ₁ 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 also as an alkyl group.
R2 and _R3 are also the same as _R2 and _R3 in formula (). Specific compounds of this formula () include α-vinylnaphthalene, isopropenylnaphthalene, allylnaphthalene, and 1-cyclopent-2-enylnaphthalene. Among these, for example, vinylnaphthalene becomes formylnaphthalene,
It can be obtained by reacting a Grignard reagent such as methylmagnesium iodide followed by dehydration. Furthermore, aromatic olefins, which are one component of the insulating oil of the present invention, can also be obtained using dehydrogenation reactions, oxidative dehydrogenation dimerization reactions, decomposition reactions, and the like. In other words, as a method using dehydrogenation reaction,
While suppressing side reactions such as decomposition and polymerization of saturated aromatic hydrocarbons corresponding to aromatic monoolefins, and saturated aromatic hydrocarbons or aromatic monoolefins corresponding to aromatic diolefins of the present invention,
It can be produced by dehydrogenating using an appropriate dehydrogenation catalyst. The dehydrogenation catalyst is not particularly limited, and any catalyst can be used. For example, one or a mixture of two or more metal oxides such as Cr, Fe, Cu, K, Mg, and Ca, and noble metals such as Pt and Pd. , or a dehydrogenation catalyst in which these metal oxides or noble metals are supported on a carrier such as alumina. Dehydrogenation reaction temperature is 350-650℃, preferably 400-600℃
It is ℃. LHSV is 0.2-10, preferably 0.5-3.0. Further, during dehydrogenation, a gas such as water vapor, nitrogen, or hydrogen may be present in order to lower the partial pressure or to prevent carbon precipitation.
Moreover, an appropriate diluent can also be used if necessary. However, it is usually advantageous if the dehydrogenation rate is not too high because the raw material itself can act as a diluent. By dehydrogenating in this manner, for example, diphenylethylene can be obtained from diphenylethane, and vinyl phenyl-phenylethane, ethyl phenyl-phenylethylene, vinyl phenyl-phenyl ethylene, etc. can be obtained from ethyl phenyl-phenylethane. Further, isopropenylbiphenyl can be obtained from isopropylbiphenyl, and isopropenyl-isopropylnaphthalene, diisopropenylnaphthalene, etc. can be obtained from diisopropylnaphthalene. Furthermore, the aromatic monoolefin, which is one component of the insulating oil of the present invention, can also be obtained by oxidative dehydrogenation dimerization. This method uses toluene, xylene,
This is a method of dimerizing (coupling) and dehydrogenating methyl group-substituted monocyclic aromatic hydrocarbons such as ethyltoluene and vinyltoluene. For example, toluene produces 1,2-diphenylethylene, and xylene produces 1,2-diphenylethylene.
(methylphenyl)ethylene is obtained respectively.
In addition, at this time, a saturated aromatic hydrocarbon corresponding to the olefin produced (for example, in toluene,
Since 1,2-diphenylethane) can also be obtained at the same time, it is convenient as a method for producing the insulating oil of the present invention. As the catalyst for this oxidative dehydrogenation dimerization, any suitable catalyst can be used. , Tl, Cd and other metal oxides, or mixtures thereof as catalysts.
Catalyst described in Publication No. 49-20561, U.S. Pat. No. 4,243,825
Examples include the Tl-based composite oxide catalyst described in the above publication.
Furthermore, an alkali metal oxide may be added to these catalysts as a promoter or promoter. During the reaction, use the above oxide as a catalyst,
It can also be carried out in the presence of molecular oxygen;
The molar ratio of aromatic hydrocarbons substituted with methyl groups is 0.01~
5.0, preferably 0.05 to 1.0. It is also possible to carry out the reaction stoichiometrically without the presence of molecular oxygen, but in this case, the oxide catalyst is reduced along with the reaction, so oxidation treatment is required in addition to the usual regeneration treatment to remove precipitated carbon. Is required. Reaction temperature is 300-800℃, preferably 500-700℃
and the contact time is 0.01 to several minutes, preferably 0.1
~30 seconds. The pressure is not particularly limited, and is from reduced pressure to 100 atm, preferably about 0.1 to 5.0 atm. Furthermore, aromatic olefins as a component of the insulating oil of the present invention can also be obtained by decomposition reactions such as thermal decomposition or catalytic decomposition. A polymer or the like can be used as a raw material. To pyrolyze these raw materials, the temperature is 300~
The temperature is 700°C, preferably 330-600°C. If the decomposition temperature is too low, the decomposition rate will be low, while if the decomposition temperature is too high, it will decompose into monocyclic aromatic hydrocarbons. Therefore, in order to obtain aromatic olefins in good yield, it is preferable to shorten the contact time in the high temperature region as much as possible. Catalytic cracking can be carried out in a liquid phase or a gas phase using silica gel, silica-alumina, kaolin, zeolite with or without dealuminization treatment, inorganic or organic sulfonic acid, etc. as a catalyst. The reaction temperature is 300-700°C, preferably 330-600°C. The aromatic olefins represented by the above formulas () to () are used by being mixed and dissolved with an aromatic ether, and it is sufficient that they become liquid at room temperature after being mixed and dissolved. Therefore, it may be either liquid or fixed at room temperature. Further, this olefin having two fused or non-fused aromatic rings can be used alone or in combination with an aromatic ether as a mixture of two or more. In the present invention, as described above, an electrical insulating oil is obtained by mixing and using the aromatic olefin in item (b) with the aromatic ether in item (a). The viscosity of the insulating oil is preferably 30 cSt or less at 40°C, more preferably 10 cSt. Therefore, so that the viscosity after mixing falls within this range, (a)
As the aromatic ether in item (b) and the aromatic olefin in item (b), compounds represented by formulas () may be appropriately selected and used. The aromatic ether itself has excellent electrical properties as well as biodegradability, heat resistance, and oxidation stability, and is also excellent in hydrogen gas absorption. Despite the further improvement in gas absorption and the combined use of unsaturated compounds such as aromatic olefins, no decrease in biodegradability, thermal stability, or oxidative stability was observed, and other electrical Various characteristics are further improved. The mixing ratio of the aromatic ether in item (a) and the aromatic olefin in item (b) is arbitrary, but it is preferable that the latter aromatic olefin be in the range of 0.01 to 50% by weight based on the total amount of both. It is preferable from the viewpoint of the synergistic effect of both components. More preferably, it is in the range of 1.0 to 30% 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, for the purpose of improving the desired electrical performance within a range that does not impair the general electrical performance, conventionally known electrical insulating oils such as polybutene, mineral oil, alkylbenzene, alkyl biphenyl, alkyl naphthalene, diaryl It can be used by adding alkanes etc. In addition, antioxidants known as electrical insulating oils,
For example, as phenols, 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) (tributylphenol), stearyl-β-(3,5-di-tert-butyl-4-hydroxyphenol)propionate (trade name Irganox1076), tetrakis[methylene-
3(3′,5′-di-tert-butyl-4′-hydroxyphenyl)propionate]methane (trade name
Irganox1010), 1,3,5-trimethyl-2,
4,6-tris(3,5-di-tert-butyl-4-
Hydroxybenzyl)benzene (product name
Ionox330), 1,1,3-tris(2-methyl-
4-Hydroxy-5-tert-butylphenol)butane (trade name Topanol CA), etc., and sulfur-based compounds such as dilaurylthiodipropionate, distearylthiodipropionate, laurylstearylthiodipropionate, and dimyristylthiodipropionate. In addition, as phosphorus compounds, triisodecyl phosphite, diphenyl isodecyl phosphite, triphenyl phosphite, trinonylphenyl phosphite, etc. can be added to the electrical insulating oil of the present invention. These antioxidants can be used individually or in a mixture of two or more, and the amount added is 0.001 to 5% by weight, more preferably 0.01 to 5% by weight based on the insulating oil.
It is 2.0% by weight. Further, phosphoric acid ester compounds, epoxy compounds, and the like, 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. As mentioned above, these oil-impregnated electrical devices
In recent years, there has been a strong demand for higher voltage and smaller size, and as a result, plastics are being used as insulating or dielectric materials for these oil-impregnated electrical devices, instead of conventional insulating paper, or in combination with insulating paper. It has become like that. Specifically, in a capacitor, a plastic film such as stretched or unstretched polypropylene, polymethylpentene, or polyester is used in combination with insulating paper as the insulator (dielectric material) of the capacitor;
Or, those using only these plastic films, and even as plastic films,
There are films that are finely embossed to make them easier to impregnate, and metallized plastic films that use a surface metal layer as an electrode. In addition, as an insulator for cables (OF cables), crosslinked or uncrosslinked polyethylene, stretched or unstretched polypropylene, polyolefin films such as polymethylpentene are used instead of insulating paper, and insulating paper and these polyolefins are used as insulators for cables (OF cables). These include laminated films laminated by melt extrusion, composite films made by cross-linking insulating paper and silane-grafted polyethylene in the presence of a silanol condensation catalyst, and mixed paper made from paper pulp and polyolefin fibers. The electrical insulating oil of the present invention has excellent compatibility with plastics, so as mentioned above, it can be used in oil-impregnated electrical equipment that uses plastic as part or all of its insulators or dielectrics, such as capacitors, etc. Suitable for impregnating cables, etc. In other words, when a capacitor using plastic, particularly polyolefin, as part or all of the insulator (dielectric) is impregnated with the electrical insulating oil of the present invention, the swelling of the plastic insulator is small; Impregnation is sufficient and no voids (unimpregnated areas) occur. Therefore, there is no fear that corona discharge will occur due to electric field concentration in the void, resulting in dielectric breakdown. Furthermore, the electrical insulating oil of the present invention has excellent hydrogen gas absorption and corona discharge resistance under high voltage, and can extend the life of oil-impregnated instruments and increase pressure. Similarly, in the case of a cable, since the dimensional change of the insulator due to swelling is small, the oil flow resistance of the insulating oil is extremely low, and the impregnation time of the insulating oil is shortened when the cable is impregnated with oil. Of course, since impregnation is easily performed, voids are less likely to occur, resulting in a higher dielectric breakdown voltage. In addition, in cables using an insulator made of a laminated film of plastic film and insulating paper or a composite film, even if they come into contact with the insulating oil of the present invention for a long period of time, delamination, peeling due to bending, wrinkles, and buckling may occur. There is little risk that such things will occur. Furthermore, since insulating oil has excellent hydrogen gas absorption properties, it is possible to obtain a cable with excellent corona discharge resistance, similar to a capacitor. Therefore, a cable with a long life and high voltage can be obtained in the same way as a capacitor. Furthermore, by impregnating an insulating oil consisting of multiple components, as a result of the synergistic effect between the components,
It improves the above properties, maintains the excellent electrical properties, biodegradability, heat resistance, and oxidation stability of each component itself, and adjusts the viscosity and pour point to a suitable range. Oil-impregnated electrical equipment can be manufactured efficiently and easily, and oil-impregnated electrical equipment that exhibits high performance can be obtained without restrictions due to usage conditions. Next, the present invention will be explained in detail with reference to Examples and Comparative Examples. Examples and Comparative Examples Table 1 summarizes the insulating oils used in the Examples and Comparative Examples. Insulating oil No. 1, 9 and 10 in Table 1
is a comparative example, and all others are examples of the present invention. In both tests, 0.2% by weight of BHT was added as an antioxidant to the insulating oil. (1) Testing of oil-impregnated capacitors A model for oil-impregnated capacitors was prepared by using two stacked polypropylene films with a thickness of 14μ as the dielectric material, and by winding and laminating aluminum foil as the electrodes in the usual manner. I made a capacitor. This capacitor was impregnated with various insulating oils under vacuum to produce an oil-impregnated capacitor with a capacitance of approximately 0.45 μF. Then apply voltage to these capacitors,
Corona discharge onset voltage (CSV) and corona discharge extinction voltage (CEV) were measured. The measured temperature is
It is 30℃. The measurement results are shown in the right column of Table 1. 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 1 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. In addition, numerical values are shown as relative values. In other words, the base aromatic ether
The value is shown as 1.0 when 100% insulating oil is used.

【table】

[Table] From the results shown in Table 1, it is clear that when the insulating oil of the present invention is impregnated into a capacitor, it exhibits much better performance than a capacitor impregnated with only aromatic ether. The compatibility with plastic film is also satisfactory. Further, insulating oil No. 9 containing aliphatic olefin was not compatible with plastic film, and it was problematic to use it in oil-impregnated electrical equipment using plastic. As explained above, the electrical insulating oil of the present invention is an electrical insulating oil that has excellent compatibility with plastic film, improves its dielectric strength, and has excellent stability against discharge energy. especially,
Plastics, for example polyolefins such as polypropylene, in the form of films can be effectively used for impregnating oil-impregnated electrical equipment in which at least a portion of the insulator (dielectric) is used.

Claims (1)

[Scope of Claims] 1 (a) an aromatic ether having two at least one type of fused or non-fused aromatic rings; and (b) an aromatic ether having two at least one type of fused or non-fused aromatic rings; Electrical insulating oil made from a unique aromatic olefin. 2. The aromatic ether according to claim 1, wherein the aromatic ether is any one of diaryl ether, arylaralkyl ether, diallkyl ether, alkoxy or cycloalkoxydiarylalkane, alkoxy or cycloalkoxydiaryl, alkoxy or cycloalkoxynaphthalene. Electrical insulation oil. 3. The electrical insulating oil according to claim 1, wherein the electrical insulating oil contains 0.001 to 5% by weight of an antioxidant.