JPH05211015A - Mica sheet-like member for high temperature electric insulation - Google Patents

Abstract

PURPOSE:To provide a mica sheet-like member for high temperature electric insulation which is excellent in heat resistance and electric insulation even under a condition of thin oxygen in the atmosphere in high temperature. CONSTITUTION:A backing member 2 is bonded by means of an adhesive agent 3 to synthetic mica paper 1 formed through a paper manufacturing process of fine mica scales of synthetic mica to obtain a mica sheet-like member for high temperature electric insulation. A carbonization preventive agent 4 is included in at least one or more layers among a layer of the synthetic mica paper 1, a bonding layer between the synthetic mica paper 1 and the backing member 2, and a layer of the backing member 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mica sheet-like member for high-temperature electrical insulation, and more particularly to a mica tape or sheet for electrical insulation, which is used as a high-temperature electrical insulation material for fireproof bus ducts, fireproof electric wires and the like.

[0002]

2. Description of the Related Art In recent years, an emergency power source has been secured from the standpoint of enabling an emergency evacuation warning or broadcasting even in the event of a fire. For the purpose of securing this emergency power supply, an integrated mica tape or sheet made of natural mica which has high temperature resistance and excellent insulation properties has been used as a fire resistant insulating layer of a fire resistant bus duct or a fire resistant electric wire.

There is a standard for such fireproof electric wires and fireproof bus ducts according to the notification of the Fire Department, and in the combustion furnace specified by the notification, from room temperature to 840 ° C. in 30 minutes according to the predetermined temperature rising curve shown in FIG. The ability to raise the temperature and maintain an insulation resistance of 600 V and an insulation resistance of 0.4 MΩ or more is required during this period.

[0004]

However, in an actual fire, there may be a case where the temperature exceeds 840 ° C and the atmosphere in which oxygen in the air is diluted is generated. In a situation in which the oxygen content in the air exceeds the limit and the natural oxygen concentration is low, fire resistant bus ducts and fire resistant wires using conventional mica tape or sheet made from natural mica may satisfy the insulation performance of 0.4 MΩ or more. could not. The cause of this decrease in insulation resistance is due to the carbonization of the adhesive impregnated in the assembled mica and the carbonization of the backing material due to the lack of oxygen in the air, and that the hydroxyl group (OH ^- group) possessed by natural mica is water. It was found that natural mica is dehydrated at about 650 ° C for hard mica and dehydrated at about 800 ° C for soft mica due to the chemical change to, and the decrease in insulation resistance is due to the change in crystal structure. ..

The present invention has been made in view of the above points, and is intended for high-temperature electrical insulation excellent in heat-resistant insulation even in a situation where oxygen in the air is dilute at a high temperature of 840 ° C., which is announced by the Fire Service Agency. It is intended to provide a mica sheet-shaped member.

[0006]

In order to achieve the above object, the mica sheet member for high temperature electrical insulation of the present invention comprises:
A mica sheet-like member for high-temperature electrical insulation, which is formed by adhering a backing material with an adhesive to a synthetic mica produced by making fine mica scales of synthetic mica, wherein the layer of the synthetic mica, the synthetic mica and the backing material. At least one of the adhesive layer between and the backing material layer contains an anti-carbonizing agent, and a synthetic mica containing at least 20% by weight of synthetic mica mixed with natural mica A mica sheet-shaped member for high-temperature electrical insulation, comprising a backing material bonded with an adhesive, wherein at least one of the above-mentioned layer of mica, an adhesive layer between the mica and the backing material, and a layer of backing material
It is characterized by containing an anti-carbonizing agent in one or more layers.

[0007]

Function: Synthetic mica having a stable crystal structure up to about 1000 ° C and the action of the carbonization inhibitor which prevents the carbonization of the adhesive or the backing material, make the oxygen in the air high at a temperature higher than 840 ° C. High insulation properties are maintained even under the circumstances.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing an embodiment of a mica sheet member for high temperature electrical insulation according to the present invention.

In the figure, 1 is a synthetic laminated mica, 2 is a backing material, 3 is an adhesive, each forming a layer, and 4 is aluminum hydroxide. The synthetic mica 1 is obtained by replacing the hydroxyl group of the synthetic mica, that is, natural mica with a fluorine group (F ⁻ group) having a strong chemical bonding force, for example, fluorine gold mica KMg ₃ (AlSi ₃ O ₁₀ ) F ₂ or fluorine. It is obtained by paper-making a fine mica scale obtained by crushing fluorine mica such as silicon mica.

The above-mentioned fluoromica is usually distributed under a normal pressure in a predetermined distribution.
Silica as a raw material (SiO₂), Magnesia (MgO),
Alumina (Al₂O₃), Fluoride (MgF₂, K₂S
iF ₆Etc.) are mixed and heated and melted to be synthesized. That special
The feature is that the heat resistant temperature is high. That is, the above theory
As you can see, natural mica contains all hydroxyl groups,
Hard mica is about 650 ℃, soft mica is about 800 ℃.
Compared with the fact that this is released as water and the crystals break,
Since elementary mica has a strong chemical bond with fluorine,
Has a crystal structure that does not decompose easily and is stable up to about 1000 ° C
It Fluorine mica is synthesized from refined raw materials
Therefore, it is pure and includes those that adversely affect the insulation characteristics.
Therefore, the insulating material has good electric characteristics.

The synthetic mica 1 forming the synthetic mica layer is impregnated with an organic or inorganic adhesive such as silicone resin, polyamide, polyimide, or polyolefin, and as a reinforcing material thereof, for example, a polyethylene film, polypropylene, polyester, or the like. , A plastic film or sheet such as nylon, or a backing material 2 such as natural fiber and glass cloth or glass yarn is bonded with an adhesive 3 to form a backing material layer and an adhesive layer, respectively.

As the adhesive 3 for forming the adhesive layer, silicone resin, polyamide, polyimide, polyolefin or the like having high insulation resistance, which is impregnated in the layer of the synthetic mica 1 is used.

Synthetic laminated mica 1, backing material 2 and adhesive 3
Each layer contains, for example, aluminum hydroxide 4 as a carbonization inhibitor. The aluminum hydroxide 4 is formed of the organic adhesive impregnated in the synthetic mica 1 or the organic adhesive 3 for adhering the synthetic mica 1 and the backing 2 or the backing 2. The organic reinforcing material or the reinforcing material containing an organic substance has an effect of preventing carbonization of each organic substance under the condition of lack of oxygen in the air at high temperature.

Under high temperature oxygen deficiency in the air, the organic substance tends to carbonize, and if carbonized, it becomes conductive and the insulation resistance decreases. Therefore, the aluminum hydroxide 4 causes the organic substance in each layer to be reduced. Acts to prevent carbonization of.

The structural formula of the aluminum hydroxide is Al
Although it is (OH) ₃ , it may be a hydrate having a structural formula of Al ₂ O ₃ .nH ₂ O, and its particle size is preferably 50 μm or less. More specifically, in order to include the synthetic mica layer in the synthetic mica layer 1, particles having a particle size of about 1 μm or less are preferable. The adhesive layer 3 for the adhesive layer between the synthetic mica layer and the backing layer 3, the backing material When used as the backing material 2 of the layer, it is preferably 50 μm or less. However, this is not the case if inclusion is possible in manufacturing operations.

In order to compare the performance of the insulation resistance test of the mica sheet-shaped member for high-temperature electrical insulation according to the present invention with a conventional structure in a refractory bus duct, samples 1, 2, The composite mica sheets of Samples 3 to 5 having the conventional structure were prepared as follows.

The composite mica sheet of Sample 1 is 200 g /
m ² of continuous synthetic mica paper to the aluminum hydroxide 10 parts by weight mixture of 100 parts by weight of the silicone resin is impregnated so that the resin charge is 4% as an adhesive synthetic mica sheet and thick glass 0.03mm cloth And are bonded together by using an adhesive obtained by mixing 100 parts by weight of a silicone resin with 20 parts by weight of aluminum hydroxide, and heating at 120 ° C.,
A composite mica sheet having a thickness of 0.18 mm was obtained.

The composite mica sheet of sample 2 is the same as sample 1 above.
In the same manner as in Sample 1, a composite mica sheet was obtained by using the composite mica obtained by mixing 50% by weight of soft mica of natural mica in a part of the synthetic mica instead of the synthetic mica in the composite mica sheet.

The composite mica sheet of Sample 3 is the same as Sample 1 above.
In the same manner as in Sample 1, a composite mica sheet was obtained by using a soft assembled mica of natural mica instead of the synthetic assembled mica in the above composite mica sheet.

The composite mica sheet of Sample 4 is 200 g /
m ² successive synthesized mica to the silicone resin as an adhesive and a glass cloth impregnated synthetic mica sheet and a thickness of 0.03mm were as weight resin is 4% bonding using a silicone resin adhesive And heat it at 120 ℃,
A composite mica sheet having a thickness of 0.18 mm was obtained.

The composite mica sheet of Sample 5 is the same as Sample 4 above.
In the same manner as in Sample 4, a composite mica sheet was obtained by using a soft assembled mica of natural mica instead of the synthetic assembled mica in the composite mica sheet of.

For the composite mica sheets of Samples 1 to 5 obtained in this way, in order to investigate the change in the electrical insulation performance during heating under the condition of lack of oxygen in the air, FIG. 2 and FIG. 3 The illustrated test sample was prepared.

That is, by using the composite mica sheet 6 obtained by cutting into a width of 190 mm, two winding plates 5-1 and 5-2 which are spirally wound 6 times on a copper plate having a thickness of 3.0 mm and a width of 40 mm are prepared. . The two winding plates 5-1 and 5-2 are arranged in parallel as shown in FIG. 2, and one end thereof has a shape in which it is expanded so as to face each other with a space of 65 mm. The thickness of the outer surface of each of the winding plates 5-1 and 5-2 of the book
Put 1.6 mm square U-shaped iron plates 7-1 and 7-2, fix them with bolts, and then iron plates 7-1 and 7-2.
1.6 mm thick U-shaped iron plates 8-1 and 8-2 are applied to both ends of and fixed with scissor bolts to prepare the test samples shown in FIGS.

In the electrical insulation performance test, 6 of the copper plate 9 was used.
The exposed copper plates 9-1 and 9-2 on the side of the ends, which are kept at a distance of 5 mm, are electrically connected to the insulation resistance tester and suspended in the electric furnace, and the lid is closed to close the electric furnace to a closed state. Then, the electric furnace was heated from room temperature to 925 ° C for 1 hour.
The temperature is raised according to the heating temperature curve of S A 1304.

The state of change in the insulation resistance during this period was measured as shown in the insulation resistance curve diagram of FIG.
The curves labeled 3, 4, and 5 respectively correspond to those made by the above composite mica sheet.

As is clear from FIG. 5, the refractory bus duct using the mica sheet-shaped member for high temperature electrical insulation according to the present invention is the same as the samples 1 and 2 even at a high temperature of 925.degree. As the curve shows, 0.4 MΩ or more is maintained. On the other hand, the composite mica sheet shown by the curves of Samples 3, 4, and 5 shows that between 30 minutes and 1 hour,
That is, the insulation resistance falls below 0.4 MΩ between 840 ° C and 925 ° C. This difference is that not only in natural mica mica, but also in composite mica sheet of synthetic mica that has excellent electrical insulation performance at high temperature, the insulation resistance is greatly reduced under the condition of lack of oxygen in the air at high temperature. The composite mica sheet containing aluminum oxide 4 also shows a decrease in insulation resistance.

It has been shown that the insulation resistance can be maintained at 0.4 MΩ or more when the synthetic mica which is thermally stable at high temperature and aluminum hydroxide 4 which prevents carbonization of organic substances are combined.

Further, as is clear from FIG. 5, from the characteristic curves of both Sample 1 and Sample 2, the refractory bus duct must withstand the rated voltage during heating, that is, the three standards which are the approval criteria of the Fire Agency. Insulation resistance is 0.4 immediately after heating
It was confirmed by an experiment that both of the items of MΩ or more and that the device withstands a voltage of 1500 V for 1 minute immediately after completion of heating pass.

Therefore, the mica sheet-shaped member for high-temperature electrical insulation of the present invention is an electrical member excellent in heat resistance and insulation resistance that can sufficiently maintain the standards set forth by the Fire Service Agency even at a high temperature of 925 ° C. and in a state of insufficient oxygen. Are formed.

Incidentally, magnesium hydroxide instead of aluminum hydroxide 4 has the same tendency as the carbonization inhibitor, and the magnesium hydroxide can be used as the carbonization inhibitor.

These carbonization inhibitors are contained in at least one of the synthetic laminated mica 1, the adhesive layer between the synthetic laminated mica 1 and the backing material 2, and the backing material layer formed by the backing material 2. According to the above description, carbonization of organic substances is prevented as described above, and at least 20% of the synthetic carbonized mica and the synthetic carbonized mica that are thermally stable at high temperatures are used.
The mica sheet-shaped member for high-temperature electrical insulation combined with the laminated mica mixed with more than wt% has sufficient insulation resistance at high temperature and can be used as a high-temperature electrical insulation material such as fireproof bus duct and fireproof electric wire.

[0032]

As described above, according to the present invention, the heat resistance can be improved even in the case where the ventilation is insufficient at high temperature or the atmosphere is deficient in oxygen under the atmosphere of a large amount of combustibles. A mica sheet-shaped member for high-temperature electrical insulation with excellent insulation is realized.

Therefore, it can be sufficiently used as a fireproof insulating layer for a fireproof bus duct or fireproof electric wire.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of a mica sheet-shaped member for high-temperature electrical insulation according to the present invention.

FIG. 2 is a cross-sectional view of an embodiment illustrating the structure of a refractory bus duct.

3 is a cross-sectional view of the central portion of FIG.

FIG. 4 is a heating temperature curve diagram defined in Japanese Industrial Standard JIS A 1304.

FIG. 5 is an insulation resistance comparison curve diagram of an example of the present invention and a conventional example.

[Explanation of symbols]

 1 synthetic laminated mica 2 backing material 3 adhesive 4 aluminum hydroxide (carbonization inhibitor)

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 16, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

[0014] In the context of the shortage of oxygen in the air at elevated temperatures, organic materials tend to carbonize, since the insulation resistance becomes conductive when carbide is lowered, the organic material in the layers by the aluminum hydroxide 4 Acts to prevent carbonization of.

Claims (2)

[Claims] 1. A mica sheet-like member for high-temperature electrical insulation, which is formed by adhering a backing material with an adhesive to a synthetic mica produced by making fine mica scales of synthetic mica. A mica sheet-like member for high-temperature electrical insulation, characterized in that an anti-carbonizing agent is contained in at least one of the adhesive layer between the laminated mica and the backing material and the layer of the backing material. 2. At least 2 synthetic mica in addition to natural mica
A mica sheet-like member for high-temperature electrical insulation, which is formed by adhering a backing material to an assembled mica mixed with 0% by weight or more with an adhesive, wherein a layer of the mica formed above, an adhesive layer between the assembled mica and the backing material, A mica sheet-like member for high-temperature electrical insulation, characterized in that at least one of the layers of the backing material contains a carbonization inhibitor.