JPS5952485B2 - electrical goods - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention improves the impregnation of an insulating medium such as an insulating oil or an insulating gas into an electrical article using an insulating film such as a capacitor or an electric cable.

Another object of the present invention is to provide an electrical article with low dielectric loss, which prevents reduction in service life due to corona discharge deterioration in the electrical article. The goal of insulating films for electrical products, especially capacitors, is to make them smaller, withstand higher voltages, and increase capacity.

It is. For this purpose, it is necessary to use a material that exhibits a high dielectric breakdown voltage, a low dielectric loss coefficient, and a low degree of insulating oil contamination. In response to these demands, the conventionally used paper as an insulating film has been successively replaced with polypropylene film. However, when a polypropylene film is used, its use is limited due to its poor impregnability with the insulating medium. It is believed that this is because if the impregnating property of the insulating medium is poor, the electrical relaxation effect of the insulating medium is lost, thereby reducing its practicality. In order to improve the impregnability of the insulating medium, attempts have been made to emboss the surface of the film to create surface irregularities, or to combine the film and non-woven fabric. It has the disadvantage that the manufacturing process is complicated.

The present inventors conducted research and arrived at the present invention with the aim of providing a film with high insulation properties and good insulating medium impregnation properties by improving the problems of films such as polypropylene.

That is, the present invention uses isotactic polypropylene and polyethylene having a melt index of 0.03 or less in a ratio of 99:
A composite film made of mixed polymers mixed at a ratio of 1 to 80:20 (weight ratio) and having a fifurlated surface is
An object of the present invention is to provide an electrical article characterized in that part or all of an insulating film of the electrical article is impregnated with an insulating medium.

The insulating film used in the present invention is made of isotactic polypropylene and has a melt index (hereinafter referred to as M-).
polyethylene with a ratio of 0.03 or less and 99■1 to 80:20
This is an oriented film that is manufactured from mixed polymers mixed at (weight ratio) and has a fifurlated surface.

Such a film can be obtained by melt-extruding the two types of polymers described above to obtain an unstretched film, and then subjecting it to at least uniaxial stretching, preferably simultaneous or sequential biaxial stretching, so that the surface is fifurlated. The stretching ratio is
There is no limitation as long as a film with a uniform thickness can be obtained. In the case of uniaxial stretching, the normal stretching ratio is about 3.8 to 10 times in the machine direction at a temperature of 120 to 155°C, and about 5 to 12 times in the transverse direction at a temperature of 135 to 155°C. The mixing ratio of isotactic polypropylene and polyethylene of M-10.03 or less used in the production of such a film is within the range of 99:1 to 80:20 (weight ratio), preferably 95: The ratio is 5 to 85:15.

When the amount of polyethylene mixed with M-1 of 0.03 or less is less than 1% (by weight), the impregnating property of the insulating medium (insulating oil or insulating gas) deteriorates. Also, the amount of polyethylene mixed is 2
If it exceeds 0 (weight)%, the surface fibrils of the obtained film will become excessive, protrusions will be formed, and the corona discharge starting voltage will decrease. As the isotactic polypropylene used in the present invention, a wide variety of commercially available products can be used, and the intrinsic viscosity (measured in tetralin at 135° C.) is usually 1.8 to 3.0.

Practically speaking, one having an intrinsic viscosity in the range of 1.8 to 2.6 may be used. Further, the isotactic index is preferably 85% or more, and practically 93% or more. Furthermore, it is preferable that the content of impurities in the polypropylene is small, and the ash content in the polypropylene is 400 (by weight) P.
pm or less [preferably 100 (weight) Ppm or less], insulating oil soluble polymer amount 3 (weight) % or less, insulating oil soluble additive amount 0.3 (weight) % or less [preferably 0.15 (weight) % or less] is practically preferable. Isotactic polypropylene is a propylene-ethylene copolymer with some ethylene copolymerized. It also includes. On the other hand, the polyethylene of M-10.03 or less used in the present invention has a density of 0.931 to 0.955 g/CI
Il2 is generally used.

In addition, it is preferable that the content of impurities in the polyethylene is small, and the ash content in the polyethylene is 400 (weight) Ppm or less [preferably 100 (weight) Ppm or less], and the amount of insulating oil soluble polymer is 10 (weight) % or less. It is practically preferable that the amount of the insulating oil soluble additive is 1.0% (by weight).

The surface of the oriented film used in the present invention has a fibrillar structure in which fine linear bundles are curved and aggregated in an arbitrary direction, and the linear bundles form finer fibrillar whiskers.

Microscopic photographs of an example are shown in FIGS. 1 and 2. The above-mentioned oriented film forms an electrical article as an insulating film for a capacitor, an electric cable, etc., and the electrical article of the present invention is formed by impregnating this electrical article with an insulating medium.
The insulating medium can be insulating oil or insulating gas, and the insulating film used in the present invention has excellent oil-impregnating properties, so electrical articles using insulating oil as the insulating medium exhibit a great effect.

Examples of insulating oil include mineral oil, silicone oil, alkylbenzene, liquid paraffin, high-pressure insulating oil (JIS standard), synthetic oil such as KIS insulating oil (manufactured by Kureha Chemical Co., Ltd.: trade name),
Examples include polyisobutylene and cottonseed oil.
A practical example of the insulating gas is sulfur fluoride. The electrical article of the present invention has an oriented film with a fibrillated surface (an insulating film formed thereon), which significantly increases the impregnability between the dielectrics of the insulating medium and between the electrode and the dielectric. Therefore, the step of impregnating the insulating medium can be completed in a short time.

In addition, the insulation properties of electrical articles after impregnation are highly reliable, and deterioration or damage caused by corona discharge is significantly reduced. The methods for measuring various characteristic values in the present invention are as follows.

(1) MI (melt index) Polyethylene at 190℃ according to JIS K676O
This is a numerical value expressed in g/10 minutes of the flow rate when melt extruded with a load of 6 kg.

(2) Take about 40 g of ash content sample in a platinum crucible and weigh the ash content after baking it at 800°C in an electric furnace. (3) Place about 40 g of an insulating oil soluble polymer sample in an alkylbenzene solvent at 100°C.
After immersion for 00 hours, the weight of the film was measured before and after treatment and calculated using the following formula.

(4) Amount of Insulating Oil Soluble Additive The film was immersed in insulating oil at 80° C., and the elution amount at the time when the change in elution amount over time reached saturation was determined by gas chromatography and was determined as the amount of soluble additive.

(5) A capacitor with a capacity of 0.5 μF was made using the corona discharge starting voltage (0SV) sample, and an AC voltage of 60 Hz at 20°C was applied to the capacitor impregnated with alkylbenzene, and the discharge starting voltage increased with time. The voltage that reached the saturation voltage was determined as the corona discharge starting voltage.

(7) Volumetric efficiency Refers to the capacitance or power transmission capacitance that can be accommodated in the total volume including a certain dielectric material and electrodes in an electrical article such as a capacitor or cable.

(8) AC breakdown strength An AC voltage of 60Hz at 20° C. was applied to the sample, and the distribution of minimum values measured at 100 points was determined, and the average breakdown voltage was determined.

(9) Tan δ Immerse the sample in alkylbenzene at 50°C and
The composite dielectric loss was measured using a high-voltage shoe-link bridge by applying a voltage of 60 HZIKV in accordance with 32O.

(Substitute) Impulse strength Measured at 20°C on a plate-shaped sample impregnated with alkylbenzene.

01) The degree of swelling was measured using oil-resistant high-voltage insulating oil No. JISl and maintaining it in a vacuum state at 80° C. for 30 days.

Q2) Three sheets of air permeability sample films were stacked and attached to a frame with a diameter of Mm while applying a surface pressure of 0.05 kg/COl2.

On the other hand, as a comparative product, three sheets of commercially available capacitor paper (18μ) were stacked and attached to the same frame as above. 0 on each side.
Gas at a pressure of 1 kg/CIn2 (gauge) was supplied, and the pressure of the gas permeated to the opposite side was transmitted to the left and right sides of the top pin, and the difference in the amount of permeated gas was qualitatively measured. Example
1 Intrinsic viscosity 2.2 (135°C tetralin solution) Isotactic polypropylene 95% (by weight) with isotactic index 96% and M-10.005 density 0.
Linear high molecular weight polyethylene 5 (945g/CIIIl2)
weight)% in powder form, and after melting and kneading, the diameter was 2.5 m.
A cylindrical pellet with a length of about 3 mm was made by molding it into a strand of m.

The pellets were melt-extruded at 270° C. using a T-die to produce an unstretched film having a thickness of 500 μm. This unoriented film was stretched 5 times in the machine direction at 150°C, stretched 8 times in the transverse direction at 155°C, and then heat-set at 160°C for about 15 seconds.

The biaxially stretched film thus obtained had a thickness of 12 μm and had spherical fibrils on the surface.

(BOP-A) On the other hand, the same polymer mixture as above was melt-extruded to obtain an unoriented film with a thickness of 120 μm, and separately, the above isotactic polypropylene alone was melted and adjusted to a thickness of 380 μm to form an unoriented film. Extrusion laminated on top.

The composite film was stretched in both longitudinal and transverse directions at the same magnification and temperature as above to obtain a biaxially stretched composite film of 12μ. (
BOP-B) Further, only the above isotactic polypropylene was melt-extruded and biaxially stretched at the same temperature and magnification to obtain a film with a thickness of 12 μm. (BOP1C)
A capacitor was made using these films with the following configuration.

Three films are stacked with aluminum foil and wound, and the capacity is 1 μF using Kureha Chemical's KIS4OO oil as the insulating oil.
Capacitors (10 each) were created. These capacitors are kept at a temperature of 100℃, and the corona discharge starting voltage (C
The results of measuring the SV) and its lifespan are shown in the table below.

From this result, the BOP-A of the present invention. BOP-B itself or BOP-A/BOP-C/BOP-A using part of these
With this configuration, effects such as a significant improvement in the corona discharge starting voltage and a reduction in the failure rate were demonstrated.

Furthermore, regarding the change over time, it is understood that in the present invention, the impregnated state is already considerably improved after one day. Example 2 M-1 and ethylene-propylene copolymer with 3% (by weight) APV content and 94% isotactic index
and polyethylene having a density of 0.02 and a density of 0.950 g/- were mixed in the proportions shown below, and stretched in the same manner as in Example 1 to obtain a biaxially stretched film with a thickness of 18 μm.

A capacitor with a capacity of 1 μF was manufactured using the film.

KIS4OO oil manufactured by Kureha Chemical Co., Ltd. was used as the impregnating oil. CSV measurement was performed to determine the quality of the impregnating oil.

The results are shown in the table below.

Example 3 The polypropylene and polyethylene in Example 1 were
After mixing 5% (by weight) and biaxially stretching at the same magnification and temperature as in Example 1, the air permeability, which indicates ease of impregnation, was compared with that of insulating paper (capacitor paper 12μ) as shown in the table below.

Note that polyethylenes with different MIs were used.

This material was used as a dielectric material for a capacitor by winding it with Al foil using two 25μ thick films, impregnating it with the impregnating oil, and maintaining it at an AC voltage of 4.0KV at 100°C for 2 months. Then, the dielectric within the scope of the present invention has no failure,
For capacitors with M-1 of 0.04 or more, failure occurred in 2 to 3 out of 10 capacitors on average. Example 4 Intrinsic viscosity 2.4, isotactic index 96%
isotactic polypropylene and M・I is 0.0
2 polyethylene with a density of 0.948 g/Cnl2 was mixed at a mixing ratio of 90 (weight)% and 10 (weight)%, and separately, only isotactic polypropylene was used, and the same as BOP-B of Example 1 was prepared. 2 in operation, stretching temperature, and magnification
The thickness of the mixed layer is 7μ, the remaining isotactic polypropylene layer is 53μ, and the total gold thickness is 60μ.
A composite film was produced.

A comparison was made with a film in which the film and cable insulating paper (thickness: 125 μm) were wound so as to be alternately laminated.

(Comparative example-1)

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 show an example of a microscopic photograph of an insulating film used in the present invention.

Claims (1)

[Claims] 1. Isotactic polypropylene and polyethylene having a melt index of 0.03 or less in a ratio of 99:1 to 89
:20 (weight ratio) of mixed polymers and has a fibrillated surface. An electrical article characterized in that the oriented film forms part or all of an insulating film of the electrical article impregnated with an insulating medium.