JPH03291808A - Insulating resin composition and fireproof electric cable using the same - Google Patents

Abstract

PURPOSE:To obtain a fireproof electric cable having improved workability and electric properties by containing Si polymer having <=40wt.% of weight loss by heating to 900 deg.C in nitrogen atmosphere as an indispensable component. CONSTITUTION:An insulating resin composition is made a composition containing Si polymer having <=40wt.% of weight loss by heating to 900 deg.C in nitrogen atmosphere as an indispensable component. Or it is an insulating resin composition containing 100 pts. by weight of Si polymer having <=40wt.% of weight loss by heating to 900 deg.C in nitrogen atmosphere and 50-150 pts. by weight of mica having 10-50mum grain size. Further, a fireproof electric cable consisting of a conductor and a fireproof layer made of said two insulating resin compositions formed directly on the conductor is provided. Consequently, a highly functional fireproof electric cable or fireproof cable having improved workability and electric properties is obtained.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an insulating resin composition, and in particular, to a fire-resistant electric wire (
The present invention relates to an insulating resin composition that can be suitably used as a fireproof coating layer for cables.

The present invention also relates to a fire-resistant electric wire (cable) provided with the above-mentioned insulating resin composition as a fire-resistant layer.

(Prior Art) Conventionally, as a fireproof layer of a fireproof electric wire, one in which a glass mica tape or the like is wrapped around the outer periphery is known. but,
This method is not only expensive, but also has poor workability because it has to be wrapped directly above the conductor.

Furthermore, recently, a technology has been disclosed (Japanese Unexamined Patent Application Publication No. 59-99616) in which an insulating inorganic filler is blended into a silicone polymer as a constituent material of the fireproof layer of a fireproof electric wire. The extrusion processability is poor due to the presence of carbon dioxide, and cracks occur in the fireproof layer after combustion, making the fireproof layer unsatisfactory in terms of strength and electrical insulation.

Furthermore, as a similar technique, a technique of blending mica and a frit such as an alkali metal oxide with a silicone polymer (Japanese Unexamined Patent Publication No. 51-107487, Utility Model Application No. 57-87416)
(Japanese Utility Model Publication No. 57-50908, Utility Model Application Publication No. 57-57)
-50909) and 200 μm in silicone polymer.
Technology for blending mica with a particle size of
No. 18221) and the like are known, and there are techniques aimed at improving productivity and performance.

(Problem H to be Solved by the Invention) In the conventional known technology as described above, there are no limitations on the specific content of the silicone polymer, which is the main component used as the fireproof layer. Silicone resins such as dimethyl silicone, methyl vinyl silicone, methyl phenyl silicone, and methyl phenyl vinyl silicone, silicone elastomers with elasticity, silicone rubber that exhibits elasticity through crosslinking, silicone faces,
A wide variety of silicone polymer uses have been disclosed, including silicone oils, silicone emulsions, silicone dispersions, and the like.

As a result of examining various silicone polymers that can be used as fireproof layers, the present inventors found that a wide variety of silicone polymers, such as those shown in conventional techniques, lacked strength after combustion. It was found that only a silicone polymer that loses weight on heating can provide an excellent insulating composition free from such problems, as well as a fire-resistant electric wire made from it, and the present invention was completed.

In addition, the present inventors have found that by using mica with a specific particle size as a fireproof layer in combination with the silicone polymer with the specific heat loss described above, the extrusion processability is good, the fireproof layer does not crack, and it has electrical insulation properties. The inventors have also discovered that it is possible to provide an extremely excellent insulating resin composition with good breakdown voltage characteristics, as well as fire-resistant electric wires made from it, and have completed the present invention.

(Means for Solving the Problems) That is, the present invention: ■ The loss on heating up to 900°C in a nitrogen atmosphere is 4
Contains 0% by weight or less of silicone polymer as an essential component,
100 parts by weight of a silicone polymer whose loss on heating up to 900° C. in a nitrogen atmosphere is 40% by weight or less and 50 to 150 parts by weight of mica having a particle size of 10 to 50 μm; The present invention also provides an insulating resin composition comprising:

Furthermore, (1) there is provided a fire-resistant electric wire in which a fire-resistant layer made of the insulating resin composition described in (1) or (2) above is provided directly above the conductor.

Furthermore, the present invention will be specifically explained.

A. Insulating resin composition; The silicone polymer used in the present invention has a loss on heating up to 900°C in a nitrogen atmosphere of 40% by weight or less;
It is important that it is selected from those containing preferably 35% by weight or less.

A silicone polymer that satisfies the above conditions has a chemical structure,
Parameters that generally specify silicone polymers, such as viscosity and properties, cannot be used to unambiguously define silicone polymers.

However, the higher the viscosity, or the higher the degree of solidity such as resin or rubber, the more usable silicone polymers can be used, but it is not clear why this is the case.

Silicone polymers that can be used include dimethyl silicone, methyl vinyl silicone,
Silicone resins and rubbers such as methylphenyl silicone and methylphenyl vinyl silicone, silicone elastomers with elasticity, silicone rubbers that exhibit elasticity by crosslinking with organic peroxides, platinum curing catalysts, etc., silicone faces, silicone oils, and silicone emulsions. Among arbitrary silicone polymers such as silicone and nolicone dispersion, only those satisfying the above conditions are used.

In addition, the silicone polymer used in the present invention includes a silicone mainly composed of addition type dimethylsiloxane units, copolymers of this and other diorganosiloxanes, and copolymers of other diorganosiloxanes. Specific examples include siloxanes, such as silicones whose main components are methylvinyl silicone, methylphenyl silicone, and the like.

An appropriate amount of an insulating inorganic filler can be added to the insulating resin composition containing the specific silicone polymer of the present invention, if necessary.

By incorporating an appropriate amount of the insulating inorganic filler, fire resistance, particularly strength resistance, can be further improved.

The amount incorporated is not particularly limited, but it can generally be 50 to 150 parts by weight, preferably 100 to 150 parts by weight per 100 parts by weight of the silicone polymer.

The insulating inorganic filler used in the present invention is not particularly limited, but generally includes various types of mica, silica, quartz, alumina, talc, fired ray, magnesia, boron nitride, etc. In particular, the use of mica is preferable from the viewpoint of fire resistance.

B. Combined use of mica with a specific particle size; In particular, by blending mica with a particle size in a specific range of 10 to 50 μm as an insulating inorganic filler into an insulating resin composition, the extrusion processability and breakage of the composition can be improved. It has good voltage resistance and, in combination with the use of the specific silicone polymer, exhibits excellent fire resistance, with no cracking occurring even when exposed to high temperatures.

If the mica particle size is 10 μm or less, there is no reinforcing property after combustion, and if it is 50 μm or more, the AC breakdown voltage value after combustion will decrease.

Further, the blending amount of mica having the specific particle size is 50 to 150 parts by weight per 100 parts by weight of the silicone polymer.

If the mica content is less than 50 parts by weight, the effect of reinforcing the fireproof layer will be small, and if the content exceeds 150 parts by weight, the strength of the fireproof layer may be good, but the insulation properties during combustion will be greatly reduced.

Of course, a small amount of the above insulating inorganic filler may be used in combination with the mica having a specific particle size of the present invention.

Furthermore, in the insulating resin composition of the present invention, a peroxide,
Additives such as vulcanizing agents such as platinum catalysts, various anti-aging agents such as phenolic, amine, and sulfur-based agents, and lubricants may be added.

C1 Fireproof Electric Wire (Cable): The fireproof electric wire (cable) of the present invention will be explained based on FIG.

That is, in order to apply the insulating resin composition of the present invention as the fire-resistant layer 2 of a fire-resistant electric wire (cable), it must contain the above-mentioned silicone polymer, or it must contain a silicone polymer and an insulating inorganic filler, especially a specific particle size. The mica-containing component is mixed with additives such as a vulcanizing agent, an anti-aging agent, and a lubricant according to a conventional method as required, and the mixture is extruded and coated directly onto the conductor 1 using a conventional extruder.

Next, an insulator layer 3 made of polyvinyl chloride, polyethylene, etc. is provided on this fireproof layer 2 to create an insulated wire core, and this insulated wire core is usually twisted together, and then an insulating layer 3 made of polyvinyl chloride, polyethylene, etc. By extrusion coating the sheath layer 4, a fireproof layer 1#l (cable) is obtained.

The fire-resistant layer 2 of the present invention may be replaced by the fire-resistant layer 2 of the present invention, which is made of mica/glass tape, silicone rubberized glass tape, asbestos tape, fiber, etc. used in conventional fire-resistant electric wires (cables).
There is no problem even if it is formed on top.

Therefore, while a wide variety of silicone polymers used as a fireproof layer in conventional fireproof wires lack strength after combustion, the fireproof wire (cable) of the present invention has a specific heating loss. Because silicone polymer is used, the fireproof layer after combustion has excellent strength and insulation properties.

In addition, in the present invention, by using mica with a specific particle size as the refractory layer 2, extrusion processability is good, the refractory layer does not crack, and electrical insulation and breakdown voltage properties are also good, making it extremely excellent. There is.

(Function) The silicone polymer used in the present invention has a small heating loss of 40% or less in a nitrogen atmosphere and a loss of 80% after combustion.
It is closely related to the phenomenon that the refractory layer becomes strong after combustion when exposed to high temperatures of 0 to 1,500℃, and this phenomenon cannot be predicted from the loss of heat on heating in a normal oxygen atmosphere. 11fj1 is uncertain.

Further, in the present invention, together with the silicone polymer, 1
When mica with a particle size in a specific range of 0 to 50 μm is blended, extrusion processability is exceptionally high compared to mica with other particle size ranges and other insulating inorganic fillers, which have poor extrusion processability due to large amounts of blending. The superior strength, reinforcing properties, and breakdown voltage properties of the side sole are unexpected.

(Examples) The present invention will be specifically explained by the following Examples and Comparative Examples, but these do not limit the scope of the present invention.

Examples 1 to 5 and Comparative Examples 1 to 9 100 g of silicone polymers having various structures, viscosities, and states shown in Table 1, or as an inorganic filler with an average particle size of 1
5μ mica 100. A sample was prepared by adding and kneading 5 g of a vulcanizing agent.

The sample was extruded into a 3CIX3C11X1 sheet using an extruder at 120"C, press-cured at 150"C for 5 minutes, and the strength was evaluated after burning at 900"C"i' for 30 minutes using a Bunsen burner. The results are shown in Table 1 below.

Table 1 shows that the strength of the refractory layer is improved because it solidifies after being burned in a nitrogen atmosphere up to 900°C.

Furthermore, in order to examine the extrusion processability of the composition, addition-type silicone rubber (100,000 cps) was added.

When a composition containing 0 parts by weight, 100 parts by weight of mica, and 5 parts by weight of a vulcanizing agent was coated by extrusion at 120'C onto a 2-diameter copper conductor, it was confirmed that it had good workability.

Examples 6 to 13 and Comparative Examples 10 to 18 Predetermined amounts of various inorganic fillers shown in Table 2 and vulcanizing agent 5 to 100 parts by weight of addition type silicone rubber (100,000 CPS)
Add and knead g and I! A resin composition was prepared, and this composition was applied to a 0.5a+ copper conductor with a diameter of 2 strokes at 120'C.
After extrusion coating to + thickness, vulcanization was performed at 150°C for 5 minutes.

The composition was burned in a Bunsen burner at 900°C for 30 minutes, and the insulation resistance during combustion and the strength of the insulating resin composition after combustion were evaluated, and the results are shown in Tables 2 and 3 below.

From the above, it can be seen that it is preferable to use mica as the inorganic filler, and that the mica particle size is preferably 10 to 50 μm, and the amount added is particularly preferably 50 to 150 parts by weight.

(Effects of the Invention) As explained above, when the insulating resin composition of the present invention is applied to the fire-resistant layer of fire-resistant electric wires (cables), the processability and electrical properties, which had conventional problems, are improved, resulting in high performance. It is expected that this material will be put to practical use as a fireproof wire (cable).

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of a fireproof electric wire according to the present invention. : Conductor fireproof layer: Insulator layer: Sheath

Claims (3)

[Claims] (1) An insulating resin composition characterized by containing as an essential component a silicone polymer whose loss on heating up to 900° C. in a nitrogen atmosphere is 40% by weight or less. (2) 100 parts by weight of a silicone polymer whose loss on heating up to 900°C in a nitrogen atmosphere is 40% by weight or less;
50 to 150 parts by weight of mica having a particle size of 50 μm. (3) A fire-resistant electric wire, characterized in that a fire-resistant layer made of the insulating resin composition according to claim (1) or (2) is provided directly above the conductor.