JPH0215511A - Flame retardant cable - Google Patents

Abstract

PURPOSE:To restrain foaming phenomenon in extrusion molding so as to prevent whitening of the surface under high humidity by providing a flame-retardant cover that sodium hydrogen carbonate applied with water repelling treatment is mixed to polyolefin polymer. CONSTITUTION:A flame retardant cover is provided, in which sodium hydrogencarbonate (sodium bicarbonate) applied with water repelling treatment is used as flame retarder, and this is mixed to polyolefin polymer. The sodium hydrogencarbonate applied with water repelling treatment is one that the powder-form sodium hydrogencarbonate is treated with water repelling agent such as silicon water repelling agent, etc., and the thermal decomposition temperature is about 300 deg.C. Hereby, the foaming at the time of extrusion covering is restrained. Also, even under the high humidity, the surface of the cable is never whitened by this water repelling treatment. Furthermore, it becomes refractory to the water and never fuses out from the flame retardant cover.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to flame-retardant electric wires and cables that exhibit excellent flame retardancy and have a good appearance.

[Conventional technology]

Electric wires and cables are generally rendered flame-retardant by providing their outermost layer with a flame-retardant coating made of a flame-retardant compound. The flame-retardant mixtures used here can be broadly classified into halogen-based and non-halogen-based.

Products that use halogen-based mixtures release harmful halogen gas in the event of a fire, which is not only harmful to the human body, but also tends to cause secondary disasters associated with the fire, such as corroding equipment. Therefore, non-halogen mixtures are preferred and are widely used today.

By the way, as non-halogen flame retardant mixtures, special
As seen in FL No. 51-46341, a mixture of aluminum hydroxide, magnesium hydroxide, or a composite of magnesium hydroxide and magnesium carbonate added to a halogen-free synthetic resin such as a polyolefin polymer is used as a flame retardant. Are known.

(Problem to be Solved by the Invention) However, in the case of using such a mixture containing aluminum hydroxide, there is a problem that foaming tends to occur when extrusion coating is used as the outer sheath of electric wires and cables. , there are practical problems.

On the other hand, magnesium hydroxide is a preferred flame retardant because it has less foaming properties than aluminum hydroxide and causes fewer processing problems. Electric wires when laid in the atmosphere,
The surface of the cable becomes white. For this reason, it is desirable to prevent the occurrence of whitening so as not to cause concerns about quality.

[Means to solve the problem]

In this invention, the solution is to use water-repellent sodium hydrogen carbonate (baking soda) as a flame retardant and provide a flame-retardant coating made of a flame-retardant mixture blended with a polyolefin polymer.

[For production]

Sodium hydrogen carbonate (Na 1cO3) has a thermal decomposition temperature of about 300°C, which suppresses foaming during extrusion. Furthermore, the cable surface will not whiten even under high humidity. Since it has been treated to be water repellent, it is poorly soluble in water and will not elute from the flame retardant coating.

[Example] Fig. 1 shows an example of the flame-retardant electric wire of the present invention, and reference numeral 1 in the figure indicates the flame-retardant electric wire. This ff1l combustion wire 1
In this method, an insulator 3 made of a halogen-free resin such as polyethylene, cross-linked polyethylene, ethylene bu[1-pyrene rubber, etc.] is provided on a conductor 2 made of copper, aluminum, etc., and a water-repellent treatment is applied to a polyolefin polymer on this insulator 3. A flame retardant layer 4 made of a flame retardant mixture containing sodium bicarbonate and cum is provided.

The water-repellent treated sodium bicarbonate used here is powdered sodium bicarbonate treated with a water-repellent agent such as a silicone water-repellent agent, and is prepared by stirring 100 parts by weight of sodium bicarbonate powder. A method in which 1 to 30 weight parts of a liquid silicone water repellent agent is added to the powder while stirring and mixing thoroughly to form a thin coating of the silicone water repellent agent on the surface of the sodium bicarbonate powder particles. can be obtained by By this water repellent treatment, the solubility of sodium hydrogen carbonate in water decreases from 8.8 g (15° C.) to 0.19 or less, making it poorly soluble.

In addition, the resin composition in which this water-repellent treated sodium hydrogen carbonate is blended is mainly composed of a halogen-free polyolefin polymer, and examples of the halogen-free polyolefin polymer include high-density polyethylene, low density polyethylene, polypropylene,
Polybutene-1 and ethylene-vinyl acetate copolymer (EV
A), ethylene-ethyl acrylate copolymer (EEA
), ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-hexene-1 copolymer, and other copolymers of ethylene and other monomers are used.

The amount of the water-repellent sodium bicarbonate to be blended is about 10 to 150ff1M parts per 100 parts of the resin composition. If the amount of water-repellent sodium bicarbonate is less than 10 parts by weight, sufficient flame retardancy cannot be obtained, and if it exceeds 150 parts by weight, the mechanical properties of the mixture will deteriorate, resulting in disadvantages.

Additionally, if necessary, aluminum hydroxide and magnesium hydroxide can be added to further enhance flame retardancy, but the amount of these added is small because foaming during extrusion coating and whitening under high humidity occur. It is more desirable that the resin composition 100
Heavy Ff! The amount is preferably 20 parts by weight or less.

[Experiment example]

An insulator made of cross-linked polyethylene with a thickness of 3 rrrta was provided on a conductor with a cross-sectional area of 24 mm', and a flame retardant coating (thickness of 2 rrrta) having the composition shown in Table 1 was extruded onto this insulator. Thus, a flame-retardant electric wire of the present invention was obtained. Regarding this flame-retardant electric wire, the oxygen index, whitening property J3 of the flame-retardant coating, and foaming property were examined.

The whitening property of the flame retardant coating is determined when the electric wire is heated at a temperature of 80℃ and a relative temperature of
The flame retardant coatings were left for 7F1 tIi under condition F of 0%, and those with no whitening observed on the surface of the flame retardant coating were rated as ○, and those with whitening observed were rated as ×.

Further, the foamability of the flame-retardant coating was expressed as the lowest temperature at which foaming was observed after the flame-retardant coating was left at a certain temperature for 10 minutes. Therefore, the higher the temperature, the lower the foaming performance during extrusion coating.

The results are also shown in Table 1.

As is clear from Table 1, when water-repellent treated sodium bicarbonate 1.1 imparts good flame retardancy, there is no whitening or foaming in 6, indicating that it is a good flame retardant.

〔Effect of the invention〕

As explained above, the flame-retardant wires and cables of the present invention are made by blending water-repellent sodium bicarbonate with polyolefin polymers, and exhibit high flame retardancy as well as low flame resistance. There is no foaming phenomenon during extrusion molding of the coating, and the surface of the flame-retardant coating does not whiten even when Pi is absorbed under high temperature and high humidity conditions. Furthermore, since it is non-halogen based, it does not emit harmful halogen gas in the event of a fire.

[Brief explanation of the drawing]

Figure 1: Makoto's invention! This is a double-sided view of an example of a combustible electric wire (city line). 4... Flame retardant layer.

Claims (1)

[Claims] A flame-retardant electric wire/cable characterized by having a flame-retardant coating made of a polyolefin polymer mixed with water-repellent sodium bicarbonate.