JPH0435844B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICABILITY The present invention has excellent corona discharge characteristics, is suitable for impregnating oil-impregnated electrical equipment, and is a method for producing an electrical insulating material capable of obtaining an electrical insulating oil that enables miniaturization and weight reduction of the electrical equipment. Regarding.
More specifically, the present invention relates to a method for producing an electrically insulating material that can obtain electrically insulating oil suitable for impregnating oil-impregnated electrical equipment using plastic film as at least a part of the dielectric or insulator. . In recent years, with the demand for higher voltage, smaller size, and lighter weight of oil-impregnated electrical equipment such as oil-impregnated capacitors and oil-impregnated cables, it has become necessary to use insulating paper as an insulator or dielectric for these equipment. Various plastic materials are being used in conjunction with insulating paper. In other words, from the standpoint of insulating and dielectric materials, polyolefins such as polypropylene and polymethylpentene, which have better dielectric strength than conventional insulating paper,
Plastic materials such as polyester, polyvinylidene fluoride resin, and polycarbonate are used. For example, in the case of oil-impregnated capacitors, these plastic films may be used together with insulating paper, or these plastic films may be used alone. Capacitors using metallized paper or metallized plastic film are also used, in which the electrode is a metal layer deposited on one or both sides of the paper or plastic film. In addition, in oil-impregnated cables, instead of insulating paper, crosslinked or uncrosslinked polyethylene, stretched or unstretched polypropylene, polyolefins such as polymethylpentene, polyester, polyvinylidene fluoride resin, polycarbonate, and other plastic films are used as insulators. 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, a composite film in which insulating paper and silane-grafted polyethylene are cross-linked in the presence of a silal condensation catalyst, or paper. There are papers made from a mixture of pulp and plastic fibers such as polyolefin. Therefore, there is a demand for an insulating oil (impregnating oil) that has excellent compatibility with these plastic materials. However, conventional electrical insulating oil,
For example, refined mineral oils, polybutenes, alkylbenzenes, etc. are not necessarily compatible with plastic materials, and as alternatives to these insulating oils, diarylalkane, alkylbiphenyl, alkylnaphthalene, etc. Aromatic hydrocarbons having two fused or non-fused aromatic rings are used as electrical insulating oils. However, the requirements regarding the performance of oil-impregnated electrical equipment are severe, and the emergence of even better electrical insulating oil is desired. In view of the above circumstances, the present inventors have conducted extensive research and have found that an electrical insulating material produced by dehydrogenating an aromatic hydrocarbon having two fused or non-fused aromatic rings is used. In particular, they discovered that a significantly superior electrical insulating oil could be obtained, and completed the present invention. That is, the present invention relates to a method for producing an electrically insulating material, which is characterized by dehydrogenating an aromatic hydrocarbon having two fused or non-fused aromatic rings. The aromatic hydrocarbon having two fused or non-fused aromatic rings used as a raw material in the present invention is:
A hydrocarbon residue from which at least one olefinic double bond is formed by a dehydrogenation reaction, that is, at least one aliphatic or alicyclic hydrocarbon residue having 2 or more carbon atoms, and is fused or non-condensed. Any compound may be used as long as it is an aromatic hydrocarbon having two aromatic rings of the same type. However, compounds having a molecular weight of about 500 or less are usually preferred since they have suitable viscosity. Specifically, they include diarylalkane (or cycloalkane), arylindane, alkyl (or cycloalkyl) biphenyl, alkyl (or cycloalkyl) naphthalene, and the like. Diarylalkane (or cycloalkane)
Examples include 1,1-diphenylethane, 1-phenyl-1-tolylethane, 1-phenyl-1-
1,1-diarylalkane such as xylylethane, 1-phenyl-1-ethyl phenylethane,
and 1,2-diarylalkane such as 1-phenyl-2-ethyl phenylethane and 1-phenyl-2-isopropylphenylethane, and diphenylcyclohexane. Examples of alkyl (or cycloalkyl) biphenyl include monoisopropyl biphenyl, diisopropyl biphenyl, cyclohexyl biphenyl, and the like. Further, examples of alkyl (or cycloalkyl) naphthalene include ethylnaphthalene, isopropylnaphthalene, and diisopropylnaphthalene. Although a catalyst is used in the dehydrogenation reaction of the present invention, any conventionally known catalyst can be used as the dehydrogenation catalyst. For example, catalysts such as metal oxides such as Cr, Fe, Cu, K, Mg, and Ca, noble metals such as Pt and Pd, or combinations of these metal oxides, noble metals, and alumina are used. The reaction temperature for dehydrogenation is 350-650℃, preferably
The temperature is 400-600℃. When carried out using a fixed bed flow system, the LHSV is 0.2 to 10, preferably 0.5 to 3. During dehydrogenation, an inert gas such as water vapor can also be present. Also, if necessary,
Appropriate diluents can also be used. However, it is usually advantageous to carry out the reaction without increasing the dehydrogenation rate so much, since the raw material itself becomes a diluent. In the dehydrogenation reaction of the present invention, the catalyst, reaction conditions, etc. may be appropriately selected in order to suppress side reactions such as decomposition. However, dehydrogenation is performed so that aromatic olefins having two fused or non-fused aromatic rings, such as mono-olefins or diolefins obtained by dehydrogenation, are contained at least 0.5% by weight, preferably at least 5% by weight. It is important to do the following. If the amount of the above aromatic olefins is less than 0.5% by weight, the effects of the present invention cannot be expected to be achieved. After completion of the reaction, if necessary, the electrical insulating material of the present invention can be obtained by distilling off light components resulting from side reactions such as decomposition and heavy components resulting from polymerization. From the electrically insulating material obtained as described above,
Electrical insulating oil is obtained as follows. That is, if it has an appropriate viscosity and the aromatic olefin content is appropriate, the reaction mixture can be used as it is as an electrical insulating oil. In addition, when the viscosity is high or the content of the aromatic olefins is large, an excellent electrical insulating oil can be easily obtained by appropriately mixing one or more types of conventionally known electrical insulating oils. . Furthermore, when the obtained electrical insulating material is solid at room temperature, it is possible to easily obtain an excellent electrical insulating oil by dissolving an appropriate amount in an appropriate electrical insulating oil that has a dissolving power for the insulating material. Obtainable. Note that the aromatic olefins produced by the dehydrogenation reaction may be isolated by appropriate means, for example, separation means such as distillation, extraction, or precipitation, but usually for reasons such as their boiling points being close to each other. Since it is difficult to isolate the electrical insulating oil from the above method, it is preferable to obtain the electrical insulating oil by the method described above. The electrical insulating oil to be mixed or dissolved is a conventionally known electrical insulating oil, such as the diarylalkane (or cycloalkane), arylindan, alkyl (or cycloalkyl) used as a raw material in the present invention. )
biphenyl, alkyl (or cycloalkyl)
In addition to two-ring aromatic hydrocarbons such as naphthalene, monocyclic aromatic hydrocarbons such as alkyl (or cycloalkyl) benzene, polybutene, diaryl ether, dialkyl ether, diaryl sulfide, phthalate esters, mineral oil, castor oil, etc. This electrical insulating oil is a mixture of one or more of animal and vegetable oils, phosphate esters such as tricresyl phosphate, etc. When the electrical insulating material of the present invention is used as an electrical insulating oil as it is, it becomes an electrical insulating oil that is highly compatible with plastic materials such as polyolefin, and the plastic material is used as at least a part of the dielectric or insulator. By impregnating oil-impregnated electrical equipment with oil, it is possible to achieve higher voltage, lighter weight, and longer life of the equipment. In addition, if it is mixed or dissolved in a hydrocarbon having at least two fused or non-fused aromatic rings, such as diarylalkane, alkylbiphenyl, alkylnaphthalene, etc. used as electrical insulating oil, or other electrical insulating oil, The same excellent effects can also be obtained due to the synergistic effects between the components used. Next, the present invention will be explained in detail with reference to Examples. Example 1 An electrical insulating material containing 51% by weight of monoisopropenyl biphenyl was obtained by dehydrogenating monoisopropylbiphenyl in the presence of water vapor under the following conditions. Dehydrogenation conditions Catalyst: Nissan Girdler Catalyst Co., Ltd. G64A (iron oxide catalyst with potassium carbonate and chromium oxide as promoters) Particle size: 14-28 mesh Temperature: 590°C LHSV: 1.0 H ₂ O/raw oil weight ratio: 3.0 Pressure: Normal pressure Next, this was diluted with monoisopropyl biphenyl as a raw material so that the monoisopropenyl biphenyl content was 10% by weight to prepare an insulating oil. A capacitor was impregnated with this insulating oil and the raw material monoisopropyl biphenyl, and the performance of the two was compared. The capacitor used two easily impregnated polypropylene films with a thickness of 14 μm as a dielectric and aluminum foil as an electrode, and the capacitance after impregnation was about 0.4 μF. Example 2 Using 1-phenyl-1-xylylethane,
The dehydrogenation reaction was carried out under the same conditions as in Example 1, except that the reaction temperature was 420°C, and 1-phenyl-1-
An electrical insulating material which is a reaction mixture containing 10% by weight of xylylethylene was obtained. Using this electrical insulating material and the raw material 1-phenyl-1-xylylethane, a capacitor made in the same manner as in Example 1 was impregnated, and the performance of the two was compared. Example 3 Using diisopropylnaphthalene, reaction temperature
A dehydrogenation reaction was carried out at 500° C. under the same conditions as in Example 1, to obtain the electrical insulating material of the present invention as a reaction mixture (dehydrogenated product) with a bromine number of 8.1 cg/g. Next, the capacitor made as follows
The obtained electrical insulating material and the raw material diisopropylnaphthalene were respectively impregnated, and the performance of both capacitors was compared. The dielectric of the capacitor is a polypropylene easily impregnated film with a thickness of 28 μm and a width of 62 mm, and insulating paper with a thickness of 12 μm and a width of 62 mm, and the electrode is made of aluminum foil with a thickness of 7 μm and a width of 50 mm. , the above reaction mixture, and diisopropylnaphthalene to prepare a capacitor with a capacity of 0.7 μF. Here, in the performance test of the capacitor in each example, corona onset voltage (CSV), corona extinction voltage (CEV), and time until capacitor breakdown under constant voltage application were measured and compared.
The results are summarized in Table 1. In addition, the capacitor
To measure the breakdown time, seven capacitors were each impregnated with the same oil, and a constant voltage was applied to cause dielectric breakdown.The remaining five samples, excluding the maximum and minimum breakdown times, were The average value was taken as the breakdown time of the capacitor. Further, in the table, the destruction time is shown as a relative value with respect to the dehydrogenation raw material in each example.

[Table] Example 4 1,1-diphenylethane at a reaction temperature of 575
Dehydrogenation was carried out under the same conditions as in Example 1 except that the temperature was changed to 0.degree. C. to obtain an oil containing 83% by weight of diphenylethylene. Next, using 1-phenyl-1-xylylethane added so that this oil becomes 10% by weight,
A capacitor was made in the same manner as in Example 1, and its performance was evaluated. The results are shown in Table 2. Example 5 1-Phenyl-1-(4'-ethylphenyl)ethane was dehydrogenated under the same conditions as in Example 1 except that the reaction temperature was 550°C to obtain an oil with the following composition. Type Weight % 1-phenyl-1-(4'-ethylphenyl)ethane 23.8 1-phenyl-1-(4'-ethylphenyl)ethylene 39.9 1-phenyl-1-(4'-vinylphenyl)ethane 5.0 1-phenyl- 1-(4'-vinylphenyl)ethylene 28.1 Others 3.2 Total 100.0 Next, using 1-phenyl-1-xylylethane to which this oil was added to make it 10% by weight,
A capacitor was made in the same manner as in Example 1, and its performance was evaluated. The results are also shown in Table 2. Note that all of the destruction times in Table 2 are relative values to the values obtained when 1-phenyl-1-xylylethane, which is a base oil, is used alone.

[Table] From the results shown in Tables 1 and 2, it is clear that the electrical insulating material of the present invention obtained by dehydrogenation has excellent properties when used as an electrical insulating oil as it is or when mixed. It turns out that it is an electrical insulating oil.
In other words, the aromatic hydrocarbons themselves used as dehydrogenation raw materials in each example have been conventionally used as electrical insulating oils, and in particular oils whose dielectric material is at least partially made of plastic. Although it is said to be suitable for impregnating impregnated capacitors, oil-impregnated cables, etc., it is clear that any insulating oil using the electrical insulating material of the present invention is superior to these raw material oils. .

Claims (1)

[Claims] 1 One or more carbon atoms selected from the group consisting of diarylalkane (or cycloalkane), arylindane, alkyl (or cycloalkyl) indane, alkyl (or cycloalkyl) biphenyl, or alkyl (or cycloalkyl) naphthalene An aromatic hydrocarbon having two or more aliphatic or alicyclic hydrocarbon residues and a molecular weight of about 500 or less is heated at 350°C to 650°C in the presence of a dehydrogenation catalyst consisting of a metal oxide or a noble metal. An electrical insulating material for an oil-impregnated capacitor using a plastic material as at least a part of the dielectric or insulator, which is characterized by being dehydrogenated to produce 0.5% by weight or more of aromatic olefin in the temperature range of °C. manufacturing method.