JPH0435843B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to 1,2-diarylalkane and 1,3-
This invention relates to an electrical insulating oil comprising a diarylbutene derivative. More specifically, oil-impregnated electrical equipment having a metal conductor or metal electrode and an insulator or dielectric made of a plastic material such as polyolefin applied to at least a part thereof, such as an oil-impregnated capacitor, an oil-impregnated cable, etc. The present invention relates to an improved electrical insulating oil comprising a 1,2 diaryl alkane and a 1,3-diaryl butene derivative suitable for impregnation. In recent years, as oil-impregnated electrical equipment such as oil-impregnated capacitors, oil-impregnated cables, and transformers have become higher voltage and smaller, various plastic materials have been 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 pollution problems. Further, various conventional electrical insulating oils are not necessarily compatible with plastic materials such as polyolefin used in the oil-impregnated electrical equipment. That is, when conventional electrical insulating oils containing, for example, alkylbenzenes, polybutenes, aliphatic olefins, etc., come into contact with these plastic materials, they can dissolve or swell the plastic materials, reducing their dielectric strength. Therefore, there has been 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. As one such high-performance electrical insulating oil, an electrical insulating oil made of 1,1-diarylalkane and 1,3-diarylbutene dielectric has been developed, but it is not always satisfactory. Nakatsuta. In view of the above circumstances, the present inventors completed the present invention as a result of intensive research. That is, the present invention provides (a) one or more 1,2 diarylalkanes, and (b) one or two 1,3-diarylbutene dielectrics represented by the following general formulas () to (). The invention relates to an electrical insulating oil comprising the above. general formula In the general formulas () to (), R ₁ to R ₄
are each a hydrogen atom or a methyl group, and R ₁
The total number of carbon atoms from R ₄ is an integer of 0 to 2. The 1,2 diarylalkane of the present invention preferably has a viscosity of 10 cSt or less at 40° C. alone or as a mixture, from the viewpoint of impregnating properties. The diarylalkane used in the present invention is a 1,2 diarylalkane in which two aryl groups are bonded to different carbon atoms, among which a preferred compound is 1,2-diarylethane,
More preferred is 1-aryl-2-phenylethane represented by the following general formula (). general formula In the above formula, R ₅ to R ₇ are the same or different and are a hydrogen atom or a C ₁ to C ₅ alkyl group, and the total number of carbon atoms of R ₅ to R ₇ is 5 or less. Specific examples of 1,2 diarylalkanes are as follows. That is, 1,2-diphenylethane,
1,2-di(methylphenyl)ethane, 1-phenyl-2-(methylphenyl)ethane, 1-phenyl-2-(dimethylphenyl)ethane, 1-phenyl-2-(ethylphenyl)ethane, 1-phenyl-2 -(methylethylphenyl)ethane,
1-phenyl-2-(isopropylphenyl)ethane, 1-phenyl-2-(trimethylphenyl)
Ethane, 1-phenyl-2-(methylphenyl)
Such as propane. These can be obtained, for example, by alkylating 1-phenyl-2-chloroethane with benzene, toluene, xylene, cumene, etc. in the presence of a Friedel-Crafts catalyst. The above-mentioned 1,2 diarylalkane may be used alone or as a mixture of two or more. The 1,3-diarylbutene derivatives represented by the above general formulas () to () can be obtained by dimerizing styrene or its alkyl derivative with an acidic catalyst such as a solid acid catalyst or a super strong acid, and both are preferably used. can. These butene derivatives have a common 1,3-diphenylbutene skeleton, and specific examples include 1,3-diphenylbutene-1, 1,3-diphenylbutene-2, 1,
3-dimethyl-1,3-diphenylbutene-1
[4-methyl-2,4-diphenylpentene-
2], 1,3-di(methylphenyl)butene-1,
Examples include 1,3-di(methylphenyl)butene-2 and 1,1-dimethyl-1,3-diphenylbutene-3 [4-methyl-2,4-diphenylpentene-1]. 1,2-diarylalkane itself has excellent electrical properties and excellent hydrogen gas absorption properties, but when used in combination with 1,3-diarylbutene derivatives, hydrogen gas absorption properties are further improved. Despite the combined use of unsaturated compounds such as , 3-diarylbutene derivatives, no deterioration in thermal stability and oxidative stability was observed. Although the mixing ratio of 1,2 diarylalkane and 1,3-diarylbutene derivative is arbitrary, it is preferable that the former be 1 to the latter 0.001 to 1.0 (weight ratio) from the viewpoint of synergistic effect. More preferably 0.01-0.5
is within the range of 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 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, 1,1-diarylalkane, alkyl bifurcated oil, etc. It can be used by adding enyl, alkylnaphthalene, etc. Generally, adding polybutene improves 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. There is a tendency to improve. 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, triisodecyl phosphite, diphenyl isodecyl phosphite, triphenyl phosphite, trinonylphenyl phosphite and the like as phosphorus compounds 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, polyester, etc. is used in combination with insulating paper as an 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 oil electrical equipment that uses plastic as part or all of its insulators or dielectrics, such as capacitors. Suitable for impregnating cables and cables. 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 plastic insulator does not swell much, so the electrical insulation is improved. The oil is sufficiently impregnated and no voids (unimpregnated areas) occur. Therefore,
There is no risk of corona discharge resulting from electric field concentration in the void resulting in dielectric breakdown. Further, the electrical insulating oil of the present invention has excellent hydrogen gas absorption properties and corona discharge resistance under high voltage, has a long life, and can achieve high 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 carried out, 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, it is possible to obtain a cable that has a long life and can be operated at high voltage, similar to 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. In Table 1, insulating oil Nos. 1, 5, and 6 are used as comparative examples. In both tests, 0.2% by weight of BHT was added as an antioxidant to the insulating oil. (1) Compatibility with polypropylene film A polypropylene film (thickness 14μ) cut into a specified shape was placed in various insulating capacitor oils at 80℃ for 72 hours.
After being immersed for a period of time, the film was taken out, and the rate of change in volume (%) of the film before and after immersion was measured. The results are shown in Table 2.
In other words, the smaller the rate of volume change, the less the film swells, the better the dimensional stability, and the better the compatibility with polypropylene film. As can be seen from the results shown in Table 2, all of the insulating oils of the present invention have good compatibility with polypropylene. (2) Oil-impregnated capacitor test A 28μ thick polypropylene film (width 62mm) and a 12μ thick insulating paper (width 62mm) were used as the dielectric, and a 7μ thick aluminum foil (width 62mm) was used as the electrode. 50mm) according to the usual method,
A model capacitor for oil impregnation was fabricated by winding and laminating. This capacitor is impregnated with various insulating oils under vacuum to create an oil-impregnated capacitor with a capacitance of approximately 0.7 μF.
was created. Next, apply voltage to these capacitors,
Corona discharge onset voltage (CSV) and corona discharge extinction voltage (CEV) were measured. Measurement temperature is 30℃
It is. The measurement results are shown in Table 2. Separately, the life of the capacitor was determined by applying a constant alternating current voltage to an oil-impregnated capacitor fabricated in the same manner and measuring the time until the capacitor broke down. . In this case, among the seven capacitors impregnated with the same insulating oil, the maximum and minimum breakdown times are excluded, the average breakdown time of the remaining five capacitors is calculated, and the results are shown in Table 2. It was shown to. In addition, the numerical values are shown as relative values. That is, it is a relative value with the breakdown time of 100% 1,2-diarylalkane insulating oil being 1.

【table】

【table】

[Table] From the results shown in Table 2, it can be seen that the product of the present invention has much better performance than the base 1,2-diarylalkane. Furthermore, when comparing insulating oils Nos. 2, 3 and 4 of the present invention with insulating oils Nos. 5 and 6 containing 1,1-type diaryl alkane, the present invention has 1,1-type diarylalkanes. It is clear that it is even better than insulating oils containing diarylalkanes. Next, insulating oil Nos. 1 to 4 shown in Table 1 above,
- Conduct the same tests as above for insulating oil Nos. 7 to 10 using 1-phenyl-1-isopropylphenylethane (1,1-diarylalkane) instead of phenyl-2-isopropylphenylethane. Ta. The compositions and test results of Insulating Oil Nos. 7 to 10 are shown in Tables 3 and 4 below.

【table】

[Table] From the above results, insulating oils No. 2 to 4 of the present invention, in which aromatic rings are attached to different carbons, are better than comparative example insulating oil No. 7, in which aromatic rings are attached to the same carbon. ~ than 10,
It can be seen that the effect of adding butene dielectric is excellent and the performance improvement rate is high. 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.

Claims (1)

[Scope of Claims] 1 (a) one or more 1,2-diarylalkane, and (b) one or more 1,3-diarylbutene derivatives represented by the following general formulas () to () Electrical insulating oil consisting of two or more types. general formula In the above general formula, R ₁ to R ₄ are each a hydrogen atom or a methyl group, and the total carbon number of R ₁ to R ₄ is an integer of 0 to 2. 2. The electrical insulation according to claim 1, wherein the 1,3-diarylbutene derivative of the general formula () is 1,3-diphenylbutene-1 or 4-methyl-2,4-diphenylpentene-2. oil. 3. The electrical insulating oil according to claim 1, wherein the 1,3-diarylbutene derivative of the general formula () is 1,3-diphenylbutene-2. 4. The electrical insulating oil according to claim 1, wherein the 1,3-diarylbutene derivative of the general formula () is 4-methyl-2,4-diphenylpentene-1. 5. The electrical insulating oil according to any one of claims 1 to 4, wherein the 1,2-diarylalkane is 1-phenyl-2-(isopropylphenyl)ethane. 6. The electrical insulating oil according to any one of claims 1 to 5, characterized in that the electrical insulating oil contains 0.001 to 5% by weight of an antioxidant.