JPS5846509A - Oil-immersed insulator film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film for oil-immersed insulators with improved oil resistance at high temperatures.

In recent years, with the increase in voltage and miniaturization of oil-immersed power equipment, there has been a demand for insulating materials with excellent electrical properties and withstand voltage. To meet this demand, insulators that combine kraft paper and plastics with excellent electrical properties are being considered. The reason why kraft paper is used here is to impregnate the trout pigeon made of this insulator with insulating oil and maintain good flow characteristics. Examples of composite forms of kraft paper and plastic include Z) a method in which a tape made of kraft paper and a plastic sheet is wound around a conductor, and 2) a method in which kraft paper tape and plastic tape are alternately wound around a conductor. and so on.

Polyolefins are often used as the above-mentioned plastics due to their electrical properties, workability, resistance, etc. However, polyolefins have a similar chemical structure to hydrocarbon insulating oils used as insulating oils. Therefore, it has the disadvantage of being damaged by insulating oil. For this reason, crystalline polyolefins with relatively good oil resistance have come to be mainly used.

By the way, as oil-immersed power equipment becomes smaller, the temperature of insulating oil tends to increase. Therefore, even if a crystalline polyolefin is used, if it is immersed in a hydrocarbon-based insulating oil at a temperature close to its crystal melting point, it will tend to be wetted or dissolved by the insulating oil.

For example, an insulator made of high-density polyethylene whose crystalline point is ~120°C cannot swell with insulating oil at a temperature of 100°C or higher, and polybupylene whose crystalline melting point is 160 to 10°C It becomes difficult to use it in insulating oil at a temperature of 00-130°C or higher. Therefore, the temperature of the insulating oil is 120~1
If there is a possibility that the temperature will rise to 30°C or higher, a crystalline polyolefin with a historically high crystalline melting point is essential. At present, only poly-4-methylpentene-1 (abbreviated as TPX) has been found to meet these conditions.

The crystal melting point of TPX is 230~240℃, 130~
Even when immersed in insulating oil at a temperature of 140° C. or higher, it dissolves into mold, compared to other crystalline polyolefins.

While TFX has the above-mentioned advantages when used in high-temperature insulating oil, TFX processed into a sheet has the disadvantage of large dimensional changes due to oil absorption when immersed in insulating oil.

Figure 1 shows the dimensions of the TPX sheet immersed in insulating oil, At
As is clear from this graph, most of the amount of oil absorbed (increase in weight) during immersion in insulating oil appears as a change in dimension in the length direction.

The reason why TPX exhibits such a peculiar phenomenon is not well understood, but it is thought to be related to the state of distortion that occurs when the molten sheet extruded from the extruder solidifies when TFX is processed into a sheet. Conceivable. That is, T.P.X.
Although it is a crystalline polyolefin like polyethylene and polypropylene, it is thought that the state of strain generation differs depending on the crystallization process and crystal structure.

In this way, when TPX sheet is immersed in insulating oil, there is a phenomenon in which the dimensions change greatly in the longitudinal direction and the sheet extends, so this '1' PX sheet is formed into a tape shape and wound around the conductor. When an insulating layer is formed, oil immersion causes the TPI tape to stretch, wrinkles occur in the insulating layer, and the insulating properties are adversely affected. In addition, since TPX has a high crystal melting point, it is in the hard class among plastic materials, and has disadvantages such as low flexibility and elongation, making it difficult to wind it around a conductor.

This invention was made in view of the above-mentioned circumstances, and the method of immersion in high-temperature insulating oil is also based on this invention. The purpose of this project is to create a film for oil-immersed insulators that has no 111, has little dimensional change, and has a high withstand voltage. It is characterized by being immersed in oil.

The present invention will be explained in detail below.

Poly-4-methylpentene-1 used in this invention is a crystalline polymer obtained by polymerizing 4'-methylpentene-1 with a Ziegler catalyst, has the following structure, and has a very high melting point (240"). It has a characteristic that it can be used stably up to 200'C.

Oh.

The poly-4-methylpentene-1 is formed into a film having a thickness of 50 mm to 10 mm by conventional means, such as an extruder equipped with a T-die. The TPX film thus obtained is then immersed in a hydrocarbon insulating oil at a temperature of 100° C. or higher. The hydrocarbon insulating oils used here include mineral oil, alkylbenzene, alkylnaphthalene, diphenylethane,
Polybutene type etc. are used. This hydrocarbon-based insulating oil is stored in a suitable container and heated to a temperature of 100° C. or higher. The temperature of the hydrocarbon-based insulating oil is preferably set to approximately the same temperature as the operating environment temperature of the oil-immersed insulating layer formed from the resulting oil-immersed insulator film, from the viewpoint of the l1lII suppression effect. Then, 'f' was placed in high temperature hydrocarbon insulating oil.
'PX film is immersed. The immersion time varies depending on the temperature of the insulating oil and the thickness of the TPX film, but 2 to 10 minutes is sufficient. After immersion for a predetermined time, the TP:I film is taken out, allowed to cool, and the insulating oil adhering to the surface is removed to obtain the desired film for oil-immersed hair ties.

The electrical properties of the resulting oil-immersed insulator film do not deteriorate in any way because the electrical properties of the insulating oil are excellent.

In this way, by immersing the film in insulating oil at a temperature of 100°C or higher, the insulating oil penetrates into the tPN film.
! 71 film is swollen by insulating oil. Due to this contemplation, the amount of expansion (dimensional change) of the film in TP: is
The amount is close to the saturated jlI full amount at the processing temperature of the insulating oil. This is because when the insulating oil swells at a certain temperature as shown in Figure 1, the insulating oil permeates through the insulating oil quickly in a relatively short period of time, resulting in swelling to nearly 70-80% of the saturated swelling amount. be. The TPX film, which has swollen to an amount close to the saturated swelling amount, has a small amount of l# moisture and is very slow in oil immersion after this treatment.
The dimensional change in the longitudinal direction is also small and slow. Therefore, the oil-immersed insulating layer formed from the TPX film obtained by this method does not suffer from inconveniences such as wrinkles and delamination. Further, by this immersion treatment, the TPX film is made lubricated by the insulating oil, increasing its flexibility and making the work easier when forming the oil-immersed insulating layer.

As mentioned above, it is possible to make T, TPX film 1# cloudy by immersion treatment for several hours of about 10 minutes.
As shown in FIG. 2, it is possible to continuously supply the wound TPXl to the dipping tank 2 for continuous treatment.

The film for oil-immersed insulators obtained in this way can be wound on a conductor as it is to form an insulating layer, or it can be attached to other plastic films, kraft paper, etc. to form a composite insulator. IIk*@shitanyo on the conductor,
Alternatively, it can be wrapped alternately with other plastic films or kraft paper onto the conductor.

Hereinafter, the present invention will be specifically explained with reference to Examples.

(Example 1) Thickness 1 formed by an extruder equipped with a chi die
ooPm! PX film at 80℃, 200℃, 12
The samples were immersed in alkylbenzene-based insulating oil at 0°C and 140°C for varying times, and the amount of swelling was determined in terms of weight increase rate.

The results are shown in Figure 1), where most of the swelling appeared as elongation in the longitudinal direction of the film.

As shown in the figure, a high degree of swelling can be imparted to the TPX film by immersing it in insulating oil at 100° C. or higher for several minutes. ! @3 What is indicated by the broken line in the figure is
This indicates the amount of saturated swelling at 140℃.
By soaking for 5 minutes at 0"C, the saturated swelling amount is approximately 8
It can be left swollen to a value of 0%. Additionally, through this treatment, the mechanical properties of TPX were improved, with a tensile strength of 3.2
~3.4 Yu/Kyoji, elongation 60-70% to tensile strength i
5t-10kg';71111'', elongation 230~2
It became 80% g and became flexible and easy to process.

[Example 2] A TPX film with a thickness of 100 μm was immersed in each of the 120° C. hydrocarbon-based insulating oils for 2 minutes. The mechanical properties of the TPX film after immersion are shown in the following table.

Further, the immersed TPX film was immersed in an alkylbenzene-based insulating oil at 140° C. for 3 days, and the amount of swelling was determined. The results are also shown in the table below.

As explained above, the film for oil-immersed insulators of the present invention is made by heating a film of poly-4-methylpentene-1 at a temperature of 10%.
Since the TPX film is immersed in a hydrocarbon insulating oil at a temperature of 0° C. or higher, the TPX film swells to a value close to its saturated swelling amount, and its dimensions change. Therefore, the oil-immersed insulating layer formed from this treated film swells little and very slowly even when immersed in high-temperature oil.
Dimensional changes caused by ** are slight, so wrinkles, wrinkles, and delamination do not occur, and the withstand voltage at high temperatures is improved. It was,
Because the insulating oil plasticizes the TePX film, treatment '1'
P! The more flexible the film is, the easier it will be to wind it onto the conductor.

[Brief explanation of drawings]

FIG. 1 is a graph showing the rate of change in dimensions and weight of TPX film when immersed in insulating oil, FIG. The figure is a graph showing the relationship between the immersion time and the amount of swelling in the immersion treatment of the present invention as the temperature of the insulating oil is varied. 1...TP! Film, 2...Immersion tank.

Claims (1)

[Claims] A film of poly-4-methylpentene-1 was heated to [100
A film for oil-immersed insulators that is immersed in disaster hydrogen-based insulating oil at temperatures above ℃.