JPH05242732A - Flame retardant electric insulator and insulated electric wire - Google Patents

Abstract

PURPOSE:To provide a flame retardant electric insulator and an insulated electric wire which shows adequate flame retardancy and at the same time excels in flexibility without the proper characteristics of electric insulation, heat resistance and the like being damaged. CONSTITUTION:Antimony trioxide of not less than 2 parts by weight is added to polymer blend of 100 parts by weight composed of polyolefin of 40 to 80% by weight and chlorine series polymer of 60 to 20% by weight, and only the chlorine series polymer thereof is cross-linked, and then the whole thereof is cross-linked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a novel flame-retardant electric material that exhibits sufficient flame retardancy and excellent flexibility without impairing the original characteristics such as electric insulation and heat resistance. The present invention relates to an insulator and an insulated wire.

[0002]

2. Description of the Related Art Conventionally, as insulating materials for electric wires and cables, polymer materials such as polyethylene, crosslinked polyethylene, ethylene / vinyl acetate copolymer, ethylene / propylene rubber, and butyl rubber have been used because of their excellent electrical insulation properties. Used, both polymeric materials are flammable.

Therefore, in the event of a fire,
In many cases, fire spreads through the cable wiring system,
In some cases, it may become a fire source, and the demand for flame retardancy in electric wires and cables is increasing. In particular, as a recent trend, it has become common for electric wires and cables used in nuclear power plants, vehicles, ships, etc. to pass the vertical tray combustion test (VTFT), which simulates the actual installation situation.

For this reason, it has been required for the insulating material for electric wires and cables to have not only the original electric insulation and heat resistance but also flame retardancy.

In order to meet such demands, a flame-retardant property is imparted to these insulating materials by adding a halogen-based powdery flame retardant to the above-mentioned halogen-free polymer material or blending the halogen-containing polymer. It is generally done.

[0006]

However, the above-mentioned method of adding the powdery halogen-based flame retardant has a problem that the phenomenon in which the flame retardant is deposited on the surface (bloom) during use causes deterioration of product quality. .. Further, in the method of blending the halogen-containing polymer, there is a problem in that the polymers are not sufficiently compatible with each other due to the difference in polarity and phase separation occurs over time, resulting in a marked decrease in mechanical properties.

The object of the present invention is to solve the above-mentioned problems of the prior art and to exhibit sufficient flame retardancy and flexibility without impairing the original characteristics such as electric insulation and heat resistance. An object is to provide an excellent new flame-retardant electrical insulator and insulated wire.

[0008]

In order to achieve the above object, the flame-retardant electrical insulation of the present invention comprises a polyolefin 40
˜80 wt% and 60 to 20 wt% of a chlorine-based polymer, 100 parts by weight of a polymer blend is added with 2 parts by weight or more of antimony trioxide, and this is crosslinked only with the chlorine-based polymer in the components, It is formed by crosslinking.

Further, the insulated wire of the present invention is an insulated wire having an insulating material on a conductor, wherein the insulating material is 40 to 80% by weight of polyolefin, and 60 to 20 of chlorine-based polymer.
2 parts by weight or more of antimony trioxide is added to 100 parts by weight of a polymer blend of 1% by weight, and the chlorine-based polymer in the component is crosslinked, and then the whole is crosslinked.

The polyolefin used in the present invention is
Polyethylene, linear low density polyethylene, ultra low density polyethylene, ethylene / vinyl acetate copolymer, ethylene /
Examples thereof include methyl acrylate copolymer, ethylene / ethyl acrylate copolymer, ethylene / methyl methacrylate copolymer, ethylene / propylene rubber, ethylene / propylene / diene terpolymer, butyl rubber, and natural rubber.

Chlorinated polymers include chlorinated polyethylene, chlorosulfonated polyethylene, chlorinated ethylene.
Examples include propylene rubber, chlorinated natural rubber, polychloroprene rubber, and chlorinated butyl rubber.

In the present invention, the blending ratio of the polyolefin and the chlorine-based polymer is limited as described above. The reason is that when the polyolefin content exceeds 80% by weight, sufficient flame retardancy cannot be obtained, and conversely, when the polyolefin content is less than 40% by weight, heat resistance is reduced. This is because it is inferior in terms of sex.

Further, at least 2 parts by weight of attimone trioxide is added to 100 parts by weight of the blend of the polyolefin and the chlorine-based polymer, because if it is less than 2 parts by weight, it is not effective as a flame retardant aid. Although the upper limit is not particularly limited, the flame retardant effect increases as the amount added is increased, but the effect is gradually saturated. Therefore, the range of 2 to 15 parts by weight is desirable.

As a method for crosslinking only the chlorine-based polymer, there is a method for dynamically crosslinking at the time of kneading using a crosslinking agent capable of crosslinking only the chlorine-based polymer, and the crosslinking agent varies depending on each polymer. .. For example, a method using thioureas or amines for chlorinated polyethylene, a method using metal oxides such as magnesium oxide or litharge for chlorosulfonated polyethylene or polychloroprene, and a method using triazine compounds for chlorinated ethylene / propylene rubber. Etc.

As a whole crosslinking method, there are a method using peroxide and a method using electric wire irradiation, which can be arbitrarily used depending on the electric wire size and use.

Therefore, 2 parts by weight or more of antimony trioxide is added to 100 parts by weight of a polymer blend consisting of 40 to 80% by weight of polyolefin and 60 to 20% by weight of chlorine-based polymer, and this is the only chlorine-based polymer in the components. By cross-linking and then cross-linking the whole, the entanglement between the polyolefin and the chlorine-based polymer increases, and a structure in which phase separation is difficult occurs. For this reason, while exhibiting sufficient flame retardancy, it is possible to suppress the reduction of mechanical properties, so there is no blooming during use, sufficient flame retardancy is exhibited, and flame retardancy excellent in flexibility. Electrical insulation is obtained. This makes it possible to obtain an insulated wire that exhibits sufficient flame retardancy and is excellent in flexibility without deteriorating the original characteristics.

In the present invention, in addition to the above-mentioned compounding agent, an antioxidant,
Compounding agents such as stabilizers, lubricants, operating agents, white fillers, carbon black and colorants may be added as appropriate.

[0018]

EXAMPLES Examples of the present invention will be described below.

According to the blending ratios shown in the columns of Examples 1 to 3 and Comparative Examples 1 to 3 in Table 1, first, all of the various components other than dicumyl peroxide were blended, and this was put into a B type Banbury mixer. After kneading, the temperature was kept at 180 ° C. and kneading was continued for another 5 minutes to carry out dynamic crosslinking except for Comparative Example 3. After the Banbury kneading, a sheet was formed with an 8-inch roll maintained at a temperature of 170 ° C. Further, these were pelletized with a pelletizer.

The pellets are placed in a stainless steel container kept at about 70.degree. A predetermined amount of dicumyl peroxide was added to this container, and dicumyl peroxide was absorbed in the pellet while rotating the container for about 15 minutes.

A part of this was formed into a sheet with a 6 inch roll and pressed at 180 ° C. for 10 minutes to form a sheet having a thickness of 1 mm.
The rest is a 40 m / m extruder (L / D =
25), a conductor having an outer diameter of 1.8 mm was extrusion-coated to a thickness of 2 mm to produce an insulated electric wire. After that, they were held in a steam atmosphere of 12 kg / cm ² for 3 minutes to carry out crosslinking, and these were used as samples.

These samples were evaluated for tensile properties and flame retardancy, and the evaluation results are shown in the lower column of Table 1. Each evaluation method is as follows.

Tensile properties: A tubular sample obtained by pulling a conductor out of an electric wire is left in a thermostatic chamber at 20 ° C. for 24 hours, and then measured at a pulling speed of 500 mm / min using a Shopper type tensile tester to measure tensile strength and elongation. I asked.

Flame retardance: tested according to UL44,
Those with a burning time of 60 seconds or less were judged to be acceptable, and those with a burning time of more than 60 seconds were judged to be unacceptable.

[0025]

[Table 1]

As is clear from Table 1, the samples of Examples 1 to 4 according to the present invention are excellent in tensile properties and flame retardancy. On the other hand, in Comparative Example 1 in which the blending amount of the chlorine-based polymer is small and in Comparative Example 2 in which antimony trioxide is not added, the flame retardance is insufficient, and in Comparative Example 3 in which the chlorine-based polymer is not dynamically crosslinked, It is recognized that the entanglement between the low density polyethylene and the chlorine-based polymer is not sufficient and the tensile properties are inferior.

Therefore, a composition containing a specified amount of polyolefin, a chlorine-based polymer and antimony trioxide is first dynamically vulcanized with a crosslinking agent capable of crosslinking only the chlorine-based polymer at the time of kneading, and then the whole is crosslinked. As a result, the entanglement between the polyolefin and the chlorine-based polymer is increased, and the structure is less likely to phase-separate, resulting in a composition with excellent tensile properties and flame retardancy, which impairs the original properties such as electrical insulation and heat resistance. Without fail, a flame-retardant electric insulator exhibiting sufficient flame retardancy and excellent flexibility can be obtained. Further, an insulated wire that exhibits sufficient flame retardancy and is excellent in flexibility can be obtained without impairing the original characteristics.

[0028]

In summary, according to the present invention, a flame-retardant electric material that exhibits sufficient flame retardancy and is excellent in flexibility without impairing the original characteristics such as electric insulation and heat resistance. An excellent effect is obtained that an insulating material and an insulated wire are obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C08L 23/02 LDD 7107-4J 23/28 LDA 7107-4J

Claims (2)

[Claims] 1. A polymer blend 10 comprising 40 to 80% by weight of a polyolefin and 60 to 20% by weight of a chlorinated polymer.
A flame-retardant electrical insulator obtained by adding 2 parts by weight or more of antimony trioxide to 0 parts by weight, crosslinking only the chlorine-based polymer in the component, and then crosslinking the whole. 2. An insulated wire having an insulating material on a conductor, wherein the insulating material is a polymer blend 1 containing 40 to 80% by weight of a polyolefin and 60 to 20% by weight of a chlorine-based polymer.
After adding 2 parts by weight or more of antimony trioxide to 00 parts by weight and crosslinking only the chlorine-based polymer in the component,
An insulated wire characterized by being entirely cross-linked.