JPH10255560A - Flame retardant wire and cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve machine characteristics and processability by covering as an insulator and/or a sheath a resin composition in which a metal hydroxide, a phosphoric compound, and a silicone are blended and added around an outer periphery of a conductor with respect to a blend between polyolefie whose blend ratio is a specific weight part ratio and acid-modified polyolefin. SOLUTION: Acid modified polyolefin, a phosphoric compound, and a silicone are blended and added to a base consisting of polyolefin and a metal hydroxide, a resin composition has its high machine characteristics and bubbled, expanded, and cured during burning. A metal hydroxide of 50 to 200wt. part, a phosphoric compound of 1wt. part or more, and a silicone of 0.5wt. part are blended and added in a blend of 100wt. part in which the blend ratio of polyolefin and acidic polyolefin is 70/30 to 99/1 at a wt. part ratio to form a resin composition. This resin composition covers as an insulator 5 and/or a sheath 10 around an outer periphery of a conductor 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant electric wire / cable, and more particularly to a flame-retardant electric wire / cable excellent in mechanical properties and workability of an insulator and / or a sheath.

[0002]

2. Description of the Related Art Resin compositions such as polyolefins have been widely used as coating materials for insulators and sheaths of electric wires and cables because of their excellent workability and electrical insulation. However, since such resin compositions such as polyolefins are all flammable, when a fire occurs, there is a risk that the resin composition will burn and propagate along a wiring system to cause fire spread.

For this reason, high flame retardancy, specifically, ULV
There has been an increasing demand for electric wires and cables having high flame retardancy at a level that passes vertical combustion tests such as W-1 vertical combustion tests and vertical tray combustion tests such as IEEE Standard 383 and IEC Standard 332.

As a method of making such a resin composition such as polyolefin flame-retardant, a method of incorporating a halogen-containing compound is generally used. As a result, a large amount of nonflammable halogen-based gas is generated from the halogen-containing resin composition due to heat at the time of fire, and the surrounding oxygen is shut off to prevent combustion.

[0005] However, although this nonflammable halogen-based gas exhibits sufficient flame retardancy, it contains a large amount of toxic substances such as hydrogen chloride and is generated in a large amount, so that it has an adverse effect on the human body. In addition, secondary disasters such as disturbing evacuation behavior and fire fighting in the event of a fire due to poor visibility in the surrounding area were sometimes caused. Further, the nonflammable halogen-based gas reacts with moisture in the air to form hydrohalic acid, which may corrode expensive machines and the like.

[0006] Therefore, recently, in consideration of fire safety, a flame-retardant resin composition in which an inorganic flame retardant such as aluminum hydroxide or magnesium hydroxide is mixed in place of a halogen compound has been proposed. Attracting attention.

The flame-retardant resin composition mixed with the inorganic flame retardant utilizes an endothermic effect when hydroxide releases water of crystallization in a fire as a flame-retardant effect. Compared with the flame-retardant resin composition mixed with the compound, it has the advantage of extremely low smoke emission, toxicity and corrosiveness.

[0008]

However, even if the wires and cables use a flame-retardant resin composition mixed with an inorganic flame retardant for the insulator and / or the sheath, the wires and cables have a small diameter. In addition, a cable whose inside is made of a combustible material such as polyethylene easily spreads the fire in the above-described vertical combustion test or the like.

Therefore, it is necessary to incorporate a large amount of metal hydroxide into the resin composition in order to impart high flame retardancy. As a result, the mechanical properties and processing of the obtained insulator and / or sheath are required. The properties have been significantly reduced.

[0010] Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a highly flame-retardant flame-retardant wire / cable excellent in mechanical properties and workability.

[0011]

According to a first aspect of the present invention, there is provided a method for mixing and adding a metal hydroxide, a phosphorus compound and a silicone to a mixture of a polyolefin and an acid-modified polyolefin. The conductor is coated with an insulator and / or a sheath around the conductor.

According to a second aspect of the present invention, the mixing ratio of the polyolefin and the acid-modified polyolefin is 7 parts by weight.
The flame-retardant electric wire according to claim 1, which is 0/30 to 99/1.
Cable.

According to a third aspect of the present invention, the resin composition is used in an amount of 50 to 200 parts by weight based on 100 parts by weight of the mixture of the polyolefin and the acid-modified polyolefin. 3. The flame-retardant electric wire or cable according to claim 1, wherein said phosphorus compound and 0.5% by weight or more of said silicone are mixed and added.

The reason for limiting the above numerical range will be described below.

The mixing ratio between the polyolefin and the acid-modified polyolefin is limited to 70/30 to 99/1 in terms of parts by weight. If the parts by weight is smaller than 70/30, the mechanical properties and workability deteriorate. When the ratio is more than 99/1, the foaming property is remarkably reduced, and the flame retardancy is reduced.

The metal hydroxide is added in an amount of 50 to 100 parts by weight of the mixture of the polyolefin and the acid-modified polyolefin.
The reason that the mixing amount is limited to 200 parts by weight is that if the mixing amount of the metal hydroxide is less than 50 parts by weight, the intended flame retardancy cannot be obtained. If the mixing amount is more than 200 parts by weight, mechanical properties and workability are remarkably increased. It is because it falls.

It is limited that 1 part by weight or more of the phosphorus compound is added to 100 parts by weight of the mixture of the polyolefin and the acid-modified polyolefin. If the amount is less than 1 part by weight, the desired flame retardancy cannot be obtained. That's why.

The reason that the addition of 0.5 part by weight or more of silicone to 100 parts by weight of a mixture of a polyolefin and an acid-modified polyolefin is limited is that if the amount is less than 0.5 part by weight, the desired flame retardancy is obtained. This is because it cannot be done.

According to the above construction, a resin composition obtained by mixing and adding a metal hydroxide, a phosphorus compound and silicone to a mixture of a polyolefin and an acid-modified polyolefin is insulated on the outer periphery of the conductor. Since it is covered as a body and / or a sheath, a highly flame-retardant flame-retardant electric wire or cable having excellent mechanical properties and workability can be obtained.

[0020]

Embodiments of the present invention will be described below.

As a result of the present inventors' intensive studies on flame retardancy, as a result of mixing and adding an acid-modified polyolefin, a phosphorus compound and silicone to a system comprising a polyolefin and a metal hydroxide, They have found that they have high mechanical properties and that they foam, expand and solidify during combustion.

The flame-retardant electric wire / cable of the present invention is based on 100 parts by weight of a mixture of a polyolefin and an acid-modified polyolefin adjusted to have a mixing ratio of 70/30 to 99/1 by weight. 50 to 200 parts by weight of a metal hydroxide and 1 part by weight or more of a phosphorus compound,
And a resin composition obtained by adding 0.5% by weight or more of silicone to the outer periphery of the conductor as an insulator and / or a sheath.

The polyolefin is not particularly restricted but includes, for example, ethylene propylene rubber, ethylene ginyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene methyl acrylate copolymer, ethylene butene copolymer, ethylene octene copolymer, polyethylene, polypropylene and the like. These may be used alone or in combination of two or more.

The acid-modified polyolefin is obtained by reacting an unsaturated carboxylic acid or a derivative thereof with a polyolefin during or after polymerization of the polyolefin to copolymerize or graft-modify the polyolefin. Examples of the polyolefin include the above-described polymers, and examples of the unsaturated carboxylic acid include acrylic acid, maleic acid, and fumaric acid.As the derivative of the unsaturated carboxylic acid,
Examples thereof include the above-mentioned metal salts, amides, esters, and anhydrides of the unsaturated carboxylic acids, and among them, maleic anhydride is particularly preferred.

The metal hydroxide is not particularly restricted but includes, for example, aluminum hydroxide, magnesium hydroxide, hydrotalcite, basic magnesium carbonate, calcium aluminate, calcium hydroxide and the like. Magnesium hydroxide, which has the highest combustion effect, is particularly preferred. Here, the surface of the metal hydroxide is desirably subjected to a surface treatment with a fatty acid, a fatty acid salt, a phosphate, a silane coupling agent, a titanate coupling agent, or the like.

The phosphorus compound is not particularly limited. For example, red phosphorus, ammonium polyphosphate,
Examples thereof include polyphosphoramide, monoguanidine phosphate, and guanylurea phosphate. Among them, red phosphorus having the highest effect is particularly preferable.

Silicone is a polymer composed of an organopolysiloxane, and includes, for example, rubber, resin, and ladder polymer. The organic group is generally a methyl group, but may be a phenyl group.

The silicones defined herein also include modified polymers in which organopolysiloxanes are incorporated during or after polymerization by a graft reaction or the like.
For example, silicone-modified polyethylene, silicone-modified ethylene vinyl acetate copolymer, silicone-modified ethylene ethyl acrylate copolymer, silicone-modified ethylene methyl methacrylate copolymer and the like can be mentioned.

Next, the method of the present invention will be described.

First, the mixing ratio is 70 / 30-9% by weight.
The polyolefin and the acid-modified polyolefin are mixed as much as 9/1.

To 100 parts by weight of the mixture of the polyolefin and the acid-modified polyolefin, 50 to 200 parts by weight of a metal hydroxide is mixed, and then 1 part by weight or more of a phosphorus compound and 0.5 part by weight or more are mixed. Silicone is added to form a resin composition.

Here, the acid-modified polyolefin improves the dispersibility of the metal hydroxide, improves the melt viscosity at the time of combustion, and controls foaming due to thermal decomposition of a polymer or the like. It is presumed that the silica structure is formed by pyrolysis itself, and the fixation and solidification of the foam cells are controlled by a synergistic effect with the phosphorus compound.

This resin composition is kneaded with a kneader set at a predetermined temperature, and then introduced into an extruder set at a predetermined temperature. With this extruder, the resin composition is extrusion-coated to a predetermined thickness as an insulator and / or a sheath on the outer periphery of the conductor to produce a flame-retardant electric wire / cable.

In the resin composition, in addition to the above components, a crosslinking agent, an antioxidant, a copper damage inhibitor, a lubricant, a pigment, and the like may be appropriately added. May be cross-linked by an electron beam or the like.

That is, in the flame-retardant electric wire / cable of the present invention, a metal hydroxide of a predetermined weight part is added to 100 parts by weight of a mixture of a polyolefin and an acid-modified polyolefin mixed at a predetermined mixing ratio. Since the resin composition obtained by mixing and adding the phosphorus compound and silicone is coated as an insulator and / or a sheath on the outer periphery of the conductor, a highly flame-retardant flame retardant having excellent mechanical properties and workability. Electrical wires and cables can be obtained.

[0036]

【Example】

(Example 1) 95 parts by weight of ethylene ethyl acrylate copolymer (melt flow rate (hereinafter referred to as MFR;
190 ° C.): 0.5, ethylene ethyl acrylate content: 15 wt%) and 5 parts by weight of acid-modified polyethylene (maleic anhydride-grafted low-density polyethylene, density (20
C): 0.32, MFR (190C): 0.3).

Next, 80 parts by weight of magnesium hydroxide (average particle size: 0.8 μm, treated with oleic acid) was added to the mixture.
And 5 parts by weight of red phosphorus (average particle size: 9 to 15 parts).
μm, red phosphorus content: 90 wt%, phenol resin coating), 3 parts by weight of silicone A (MFR (190 ° C.):
0.5, silicone-grafted ethylene ethyl acrylate copolymer, dimethyl silicone content: 60 wt
%), 0.5 parts by weight of 4,4'thiobis (6-tert-butyl-4-methylphenol), 0.5 parts by weight of stearic acid, and 5 parts by weight of FEF carbon black Is prepared.

Example 2 90 parts by weight of ethylene ethyl acrylate copolymer and 10 parts by weight of acid-modified polyethylene are mixed.

Next, 100 parts by weight of magnesium hydroxide was mixed with the mixture, and then 4 parts by weight of red phosphorus and 4 parts by weight of silicone A were added. Make things.

Example 3 80 parts by weight of ethylene ethyl acrylate copolymer and 20 parts by weight of acid-modified polyethylene are mixed.

Next, 120 parts by weight of magnesium hydroxide was mixed with this mixture, and then 2 parts by weight of red phosphorus and 2 parts by weight of silicone A were added. Make things.

Example 4 90 parts by weight of ethylene ethyl acrylate copolymer and 10 parts by weight of acid-modified polyethylene are mixed.

Next, 70 parts by weight of magnesium hydroxide was mixed with this mixture, and then 10 parts by weight of red phosphorus, 5 parts by weight of silicone B (dimethyl silicone, viscosity (25%)
C): 300,000 to 900,000 cps), and thereafter, a resin composition is prepared in the same manner as in Example 1.

Comparative Example 1 80 parts by weight of magnesium hydroxide was mixed with 100 parts by weight of ethylene ethyl acrylate copolymer, and then 3 parts by weight of red phosphorus and 5 parts by weight of silicone A were added. A resin composition is prepared in the same manner as in Example 1.

Comparative Example 2 90 parts by weight of ethylene ethyl acrylate copolymer and 10 parts by weight of acid-modified polyethylene are mixed.

Next, 30 parts by weight of magnesium hydroxide was mixed with this mixture, and then 4 parts by weight of red phosphorus and 4 parts by weight of silicone A were added. Make things.

Comparative Example 3 95 parts by weight of ethylene ethyl acrylate copolymer and 5 parts by weight of acid-modified polyethylene were mixed.

Next, 250 parts by weight of magnesium hydroxide were mixed with this mixture, and then 3 parts by weight of red phosphorus and 3 parts by weight of silicone A were added. Make things.

Comparative Example 4 90 parts by weight of ethylene ethyl acrylate copolymer and 10 parts by weight of acid-modified polyethylene are mixed.

Next, after mixing 70 parts by weight of magnesium hydroxide with this mixture, 5 parts by weight of silicone A are added, and thereafter a resin composition is prepared in the same manner as in Example 1.

Comparative Example 5 85 parts by weight of ethylene ethyl acrylate copolymer and 15 parts by weight of acid-modified polyethylene were mixed.

Next, 10 parts by weight of magnesium hydroxide was mixed with this mixture, and then 5 parts by weight of red phosphorus was added. Thereafter, a resin composition was prepared in the same manner as in Example 1.

FIG. 1 shows a cross-sectional view of a flame-retardant electric wire / cable in the embodiment.

As shown in FIG. 1, the outer periphery of the optical fiber 4 formed by covering the outer periphery of the core 2 with the clad 3 is made of low-density polyethylene (density: 0.92, MFR (190 ° C.):
An optical fiber 6 is produced by coating with the insulator 5 of 1).

Three optical fibers 6 are twisted to form a stranded wire, a polyester pressing tape 7 is wound around the outer periphery of the stranded wire, and a kraft interposition 8 is filled in a gap between the stranded wire and the polyester pressing tape 7. Then, the stranded wire 9 is formed.

Each of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 5 was kneaded with a 40 mm biaxial kneader set at 200 ° C., and then each resin composition was extruded with a 90 mm extruder set at 200 ° C. The outer periphery of the stranded wire 9 is wound with a machine.
The cable 1 is formed by extrusion coating with a thickness of 5 mm.

For each cable prepared using the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 5 as a sheath material,
Mechanical properties, foamability, and flame retardancy were evaluated.

(Mechanical properties) After stripping the sheath from each cable and polishing both sides of each sheath with a grinder,
A 5-point tensile test was performed for each sheath in accordance with IS standard C3005, and the arithmetic average of the test values was used as the tensile strength (MPa).
And elongation (%).

(Foamability) The sheath peeled off from the cable was made 3.5 mm thick with a hot roll at 170 ° C.
It was formed in a thickness of 3 mm by a hot press at a temperature of 3 ° C. Then 30mm
X 30mm x 3mm
According to the standard C3005, the reducing flame of Bunsen burner is 3
Burn for 0 minutes. The shape after burning was measured, and the foaming ratio was determined by dividing the volume after burning for 30 minutes by the volume before burning.

(Flame retardancy) According to the IEEE 383 standard,
Each cable was attached to a vertical tray and fired for 20 minutes. At the extinction stage after 20 minutes, the carbonization length of the sheath of each cable was measured, and the carbonization length was less than 180 cm,
Those exceeding 180 cm were rejected.

Table 1 shows the specifications of each resin composition and the evaluation (test results) of the sheath material of each cable produced using each resin composition.

[0062]

[Table 1]

As shown in Table 1, the sheath materials of the cables manufactured using the resin compositions of Examples 1 to 4 all had a tensile strength of 10 MPa or more and an elongation of 400%.
As described above, the electrical equipment standard satisfied the polyethylene standard value. In addition, since the foaming ratio after burning was as high as 2.0 times or more, the flame retardancy in the vertical tray burning test was also passed as a result.

On the other hand, although the sheath material of the cable manufactured using the resin composition of Comparative Example 1 had good mechanical properties, the mixing ratio of polyolefin and acid-modified polyethylene (without mixing of acid-modified polyethylene) ) Was out of the specified range (70/30 to 99/1), so that the foamability was extremely low (expansion ratio 1.5), and the flame retardancy was rejected.

Although the sheath material of the cable manufactured using the resin composition of Comparative Example 2 exhibited the highest mechanical properties in the examples, the mixing amount of magnesium hydroxide as a metal hydroxide (30 wt. Parts) is out of the specified range (50 to 200 parts by weight), so that foamability is extremely low (expansion ratio 1.
8) The flame retardancy was rejected.

The sheath material of the cable produced using the resin composition of Comparative Example 3 had a high expansion ratio after burning of 2.0 times, and although the flame retardancy was acceptable, the mixing amount of magnesium hydroxide ( (250 parts by weight) is out of the specified range (50 to 200 parts by weight), so that the mechanical properties are extremely low (tensile strength:
8.9 MPa, elongation: 50% or less), and did not satisfy the polyethylene standard value of electrical appliance standards.

Although the sheath material of the cable produced using the resin composition of Comparative Example 4 had good mechanical properties, the amount of red phosphorus, which is a phosphorus compound, was added (no red phosphorus was added).
Was out of the specified range (1 part by weight or more), the foaming property was extremely low (expansion ratio 1.6), and the flame retardancy was rejected.

Although the sheath material of the cable produced using the resin composition of Comparative Example 5 had good mechanical properties, the amount of silicone added (no silicone added) was out of the specified range (0.5 parts by weight or more). , The foamability was extremely low (expansion ratio 1.5), and the flame retardancy was unacceptable.

[0069]

In summary, according to the present invention, a mixture of a polyolefin and an acid-modified polyolefin is mixed with a metal hydroxide, a phosphorus compound, and silicone.
The resin composition added is placed on the outer periphery of the conductor with an insulator and / or
Alternatively, by coating as a sheath, an excellent effect that a highly flame-retardant flame-retardant electric wire or cable having excellent mechanical properties and workability can be obtained can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section of a flame-retardant electric wire / cable in an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cable (flame-retardant electric wire / cable) 4 Optical fiber wire (conductor) 5 Insulator 6 Optical fiber (flame-retardant electric wire / cable) 9 Winding stranded wire (conductor) 10 Sheath

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hitoshi Kashimura 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Inside the Hidaka Factory, Hitachi Cable, Ltd. (72) Inventor Kazuhiko Kobayashi 5 Hidakacho, Hitachi City, Ibaraki Prefecture No. 1-1, Hidaka Factory, Hitachi Cable, Ltd.

Claims (3)

[Claims] 1. A resin composition obtained by mixing and adding a metal hydroxide, a phosphorus compound, and silicone to a mixture of a polyolefin and an acid-modified polyolefin, and insulating and / or sheathing the outer periphery of the conductor. Flame-retardant electric wires and cables characterized by being coated as follows. 2. The mixing ratio between the polyolefin and the acid-modified polyolefin is 70/30 to 99 / parts by weight.
The flame-retardant electric wire / cable of claim 1. 3. The resin composition according to claim 1, wherein the metal hydroxide is 50 to 200 parts by weight, the phosphorus compound is at least 50 parts by weight, based on 100 parts by weight of the mixture of the polyolefin and the acid-modified polyolefin. 3. A flame-retardant electric wire or cable according to claim 1, wherein said silicone is mixed and added in an amount of 0.5 part by weight or more.