KR20080107316A - Halogen free flame retardant electronic wire - Google Patents

Abstract

A halogen-free flame retardant cable is provided to ensure superior withstand voltage and flexibility by appropriately setting the resin combination of an insulation material consisting of 2 layers of the outer layer and internal layer. A halogen-free flame retardant cable(1) insulates the peripheral part of an electrical conductor(2) with an insulation material(5) consisting of 2 layers of an outer layer(4) and an internal layer(3). The internal layer is added with maleic anhydride-modified ethylene ethylacrylate copolymer(maleic anhydride denaturation rate 1 - 40%) 5 - 40 parts by weight and metal hydroxide base on 100.0 parts by weight of ethylene acetic acid vinyl copolymer having the content of acetic acid vinyl of 60 - 80%. The outer layer is added with metal hydroxide to an ethylene acetic acid vinyl copolymer having the content of acetic acid vinyl of 30 - 60%.

Description

Halogen Free Flame Retardant Wire {HALOGEN FREE FLAME RETARDANT ELECTRONIC WIRE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a halogen-free flame-retardant wire having flexibility and breakdown voltage using a halogen-free insulating resin composition used for internal wiring of electrical equipment and the like.

In recent years, in response to environmental problems, a halogen-free flame retardant resin composition in which no harmful halogen gas such as dioxins are generated during combustion has been developed, and has been used as an insulating coating material for wiring and cables. As a halogen-free flame-retardant resin composition, what added metal hydroxide as a flame retardant to copolymers, such as ethylene vinyl acetate copolymer (EVA) and maleic anhydride modified ethylene ethylacrylate copolymer (maleic anhydride modified EEA), is known. (See, eg, Patent Document 1).

On the other hand, in order to improve the flame retardancy, when the amount of the flame retardant added is increased, the mechanical and electrical properties are lowered. As a countermeasure against this, it is known to form the insulating layer of an electric wire in two layers, an inner layer and an outer layer. However, polyolefin burns when 300 parts by weight of magnesium hydroxide is added to 100 parts by weight of polyolefin to further flame retard the outer layer, and when the wire which thickens the layer of the electric insulator is exposed to the flame to secure mechanical and electrical properties. Fluidized in the city, which is gasified and combusted.

On the other hand, in the technique disclosed, for example, in patent document 2, the electric wire of the following structure is disclosed.

The inner layer is one in which 50 to 150 parts by weight of a flame retardant is added to 100 parts by weight of the base resin. There are two kinds of base resins. One is an ethylene ethylacrylate copolymer (EEA) having an ethyl acrylate (EA) content of 9 to 35 wt%. Another is a mixture of different polyolefins in the EEA. Flame retardants include magnesium hydroxide and the like.

The outer layer is one in which 150 to 300 parts by weight of a flame retardant is added to 100 parts by weight of the base resin. There are four base resins. First is EEA with an EA content of 15 to 35 wt%. Second is a mixture of EEA and other polyolefins. Third is an ethylene vinyl acetate copolymer (EVA) having a vinyl acetate (VA) content of 15 to 45 wt%. Fourth is a mixture of EVA and other polyolefins. Flame retardants are magnesium hydroxide and the like.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2003-160709

[Patent Document 2] Japanese Patent Application Laid-Open No. 2006-286529

Although a halogen-free flame-retardant wire having flexibility and a breakdown voltage is required, adding maleic anhydride-modified EEA to EVA of the base resin lowers the elongation of the electrical insulator. That is, the flexibility as an insulated wire is lowered and becomes hard. On the other hand, by adding maleic anhydride modified EEA to EVA of base resin, moisture absorption of an electrical insulator can be suppressed and the breakdown voltage of an insulated wire can be improved.

Moreover, it can be made flexible by making VA content rate of EVA which is a base resin high. However, when the VA content rate of EVA is increased, the wires stick together when the insulated wire is wound, and there is a problem that the tensile strength is also lowered and it is easy to break.

This invention is made | formed in view of the above-mentioned situation, and an object of this invention is to provide the halogen-free flame-retardant electric wire which has the outstanding characteristic of both flexibility and a breakdown voltage by optimizing the resin mixture of the electrical insulator which consists of two layers of an inner layer and an outer layer. .

The halogen-free flame-retardant wire according to the present invention is a halogen-free flame-retardant wire insulated from the outer circumference of the electrical conductor with an electrical insulator consisting of an inner layer and an outer layer. 5-40 weight part of maleic anhydride modified ethylene ethylacrylate copolymers (maleic anhydride 1-40%) with respect to 100 weight part of ethylene vinyl acetate copolymers whose content of vinyl acetate is 60% or more and 80% or less. And a metal hydroxide are added, and the outer layer is characterized in that the metal hydroxide is added to the ethylene vinyl acetate copolymer having a vinyl acetate content of 30% or more and less than 60%. In addition, the thickness of the outer layer is preferably formed thinner than the thickness of the inner layer.

According to the present invention, flexibility can be secured by increasing the vinyl acetate content of the ethylene vinyl acetate copolymer as the base resin of the inner layer, and the breakdown voltage can be increased by adding a ternary copolymer of polyethylene, maleic anhydride and ethyl acrylic acid. In addition, by lowering the vinyl acetate content of the ethylene vinyl acetate copolymer, which is the base resin of the outer layer, the surface of the electrical insulator is made hard to prevent the wires from adhering to each other and to increase the tensile strength of the wires. It can be set as a halogen-free flame-retardant wire provided with both.

The halogen-free flame retardant wire 1 according to the present invention, as shown in FIG. 1, has an electric conductor 2 covered with an electric insulator 5 composed of two layers, an inner layer 3 and an outer layer 4. Or cable. As the electric conductor 2, for example, a tin-plated single core interlocking wire having a cross-sectional circular shape or a tin-plated interlocking wire twisted with seven is used. Both the inner layer 3 and the outer layer 4 of the electrical insulator 5 have an ethylene vinyl acetate copolymer (EVA) of a polyolefin resin as a base resin, and the flame retardant of halogen-free, in which a metal hydroxide is added as a flame retardant thereto. Resin is used.

Since EVA used as a base resin has oxygen in a molecule | numerator, it has the property of high flame retardancy by itself, and high affinity with a metal hydroxide. In addition, EVA is a thermoplastic resin obtained by copolymerizing ethylene and vinyl acetate (VA). However, as the content of VA increases, the flexibility increases and behaves like rubber. A small content of VA exhibits the same physical properties as low-density polyethylene, but it has toughness and tensile strength. In order to obtain the flexibility of the electric wire, when EVA is used for the electrical insulator 5 with a high content of VA, the surface of the electric wire becomes sticky and the contact portions of the electric wire tend to stick to each other, making handling difficult.

In the present invention, the VA content in the EVA of the inner layer 3 of the electrical insulator 5 is increased, so that flexibility as an electric wire can be easily obtained inside the device, and the EVA of the outer layer 4 can be obtained. The VA content is reduced so that the surface of the electrical insulator 5 is hardened. Specifically, the VA content of the inner layer 3 is 60% or more and 80% or less to give flexibility, and the VA content of the outer layer 4 is less than 60% and 30% or more, thereby making it hard. As a result, the outer surface of the electrical insulator 5 is not sticky, and the tensile strength can be secured to some extent, so that the winding of the electric wire and the handling in the wiring can be facilitated.

In addition, maleic anhydride-modified ethylene ethylacrylate copolymer (EEA) is added to EVA of the inner layer 3. This maleic anhydride modified EEA enhances heat resistance and mechanical strength but lowers elongation. However, maleic anhydride-modified EEA has an effect of suppressing the expansion of the electrical insulator by water, and therefore, it is possible to improve the withstand voltage characteristics of the electrical insulator by adding it. Moreover, EEA which is not maleic anhydride modified does not have a swelling inhibitory effect. Moreover, since there is no ionic bond between acidic groups, the bond with EVA falls, and the required breaking strength is also not obtained.

Specifically, the modification rate of maleic anhydride modified EEA is 1 to 40%, about 5 to 40 parts by weight is added to 100 parts by weight of EVA, and preferably 15 to 35 parts by weight. If the amount is less than 5 parts by weight, the effect of suppressing moisture absorption is not expected very much. If the content is more than 40 parts by weight, the crystal component increases, so that flexibility, flexibility, and the like deteriorate.

In order to ensure the flexibility of the electric wire, it is preferable to make the thickness of the outer layer 4 which is low in flexibility compared with the inner layer 3 smaller than the thickness of the inner layer 3. The total thickness of the electrical insulator 5 varies depending on the required breakdown voltage, the thickness of the electrical conductor, and the like. For example, the rated voltage is 6 kV (AC), and the electrical conductor size to be used is AWG 20 to 30 (diameter 0.81 mm to 0.25 mm). In this case, the thickness of the inner layer 3 is 0.4 mm to 0.5 mm, the thickness of the outer layer 4 is 0.1 mm to 0.2 mm, and the total thickness of the inner layer and the outer layer is preferably 0.5 mm to 0.7 mm. If the thickness of the electrical insulator 5 is made too thick, it is difficult to bend and the flexibility is also lowered, the handleability is deteriorated, and a large amount of wiring space in the device is required and the device is enlarged.

In addition, metal hydroxides are added to each of the inner layer 3 and the outer layer 4 of the electrical insulator 5 as flame retardants as in the prior art. As the metal hydroxide, for example, magnesium hydroxide, aluminum hydroxide, calcium hydroxide and the like are used. Among them, magnesium hydroxide is preferable because of its high flame retardant effect. In addition, these metal hydroxides are selected from the group consisting of titanate coupling agents, vinylsilanes, epoxysilanes, aminosilanes, silane coupling agents such as methacrylsilanes, stearic acid, oleic acid, and lauric acid in order to increase affinity with the base resin. You may use what surface-treated using the fatty acid.

The flame retardant made of this metal hydroxide is added 50 parts by weight to 200 parts by weight with respect to 100 parts by weight of the base resin of the inner layer 3 and the outer layer 4 of the electrical insulator. Although the specific addition amount is determined according to the required flame retardancy, if it is less than 50 weight part, flame retardance is insufficient, and when it exceeds 200 weight part, the breaking strength and elongation of an electrical insulator will fall.

In addition, any of the inner layer 3 and the outer layer 4 of the electrical insulator 5 made of the halogen-free flame retardant composition described above may be subjected to weakening of the resin due to thermal oxidation with respect to 100 parts by weight of the base resin. 0.1 parts by weight to 5.0 parts by weight of an antioxidant to inhibit may be added. In addition, various auxiliary agents such as processing aids, colorants, and stabilizers for improving the formability of the electrical insulator 5 can be added.

The halogen-free flame retardant electric wire 1 in this invention is based on UL standard 758, and shall satisfy | fill the result as shown below.

(1) About flame retardance, it passed UL VW-1.

(2) About flexibility (extension), the elongation at break of the electrical insulator (tube) remaining after extracting the electrical conductor from the electric wire is 150% or more.

(3) About tensile strength, the breaking strength of the electrical insulator (tube) of the same degree is 10.3 Mpa or more.

(4) Regarding the breakdown voltage (when the rated voltage is AC 6kV), after immersing the wire bundle in water for 24 hours (the end part is taken out), apply a voltage of 13kV between water and the wire for 1 minute, and there is no voltage breakdown. .

(Example 1)

Electrical conductor: tinned copper wire (AWG24 conductor configuration 7 / 0.203 outer diameter 0.61 mm)

Electrical insulator (inner layer): 100 parts by weight of EVA with 70% VA content

20 parts by weight of maleic anhydride modified EEA (modification rate 25%)

180 parts by weight of magnesium hydroxide

2 parts by weight of antioxidant

Layer thickness 0.42mm

Electrical insulator (outer layer): 100 parts by weight of EVA with 50% VA content

180 parts by weight of magnesium hydroxide

2 parts by weight of antioxidant

Layer thickness 0.13mm

The wire of Example 1 clears a predetermined flame retardancy standard (UL VW-1), withstand voltage of 13 kV (1 minute), elongation of 170%, tensile strength of 11.5 MPa, and a predetermined value. Satisfactory results were obtained.

(Example 2: Inner layer and outer layer have the same thickness)

Electrical conductor: tinned copper wire (AWG24 conductor configuration 7 / 0.203 outer diameter 0.61 mm)

Electrical insulator (inner layer): 100 parts by weight of EVA with 70% VA content

20 parts by weight of maleic anhydride modified EEA (modification rate 25%)

180 parts by weight of magnesium hydroxide

2 parts by weight of antioxidant

Layer thickness 0.27 mm

Electrical insulator (outer layer): 100 parts by weight of EVA with 50% VA content

180 parts by weight of magnesium hydroxide

2 parts by weight of antioxidant

Layer thickness 0.27 mm

The electric wire of the said Example 2 is the example which made the thickness of the inner layer and outer layer the same in Example 1, clears a predetermined flame-retardance specification (ULVW-1), and withstand voltage clears 13 kV (1 minute). Although the elongation was 150% and the tensile strength was 10.5 MPa, the result which satisfy | filled the predetermined value was obtained, but the elongation and tensile strength were inferior to Example 1 somewhat.

(Comparative Example 1: No maleic anhydride modified EEA was added to the inner layer)

Electrical conductor: tinned copper wire (AWG24 conductor configuration 7 / 0.203 outer diameter 0.61 mm)

Electrical insulator (inner layer): 100 parts by weight of EVA with 70% VA content

180 parts by weight of magnesium hydroxide

2 parts by weight of antioxidant

Layer thickness 0.42mm

Electrical insulator (outer layer): 100 parts by weight of EVA with 50% VA content

180 parts by weight of magnesium hydroxide

2 parts by weight of antioxidant

Layer thickness 0.13mm

(Comparative Example 2: EEA of inner layer is not modified with maleic anhydride)

Electrical conductor: tinned copper wire (AWG24 conductor configuration 7 / 0.203 outer diameter 0.61 mm)

Electrical insulator (inner layer): 100 parts by weight of EVA with 70% VA content

20 parts by weight of EEA

180 parts by weight of magnesium hydroxide

2 parts by weight of antioxidant

Layer thickness 0.42mm

Electrical insulator (outer layer): 100 parts by weight of EVA with 50% VA content

180 parts by weight of magnesium hydroxide

2 parts by weight of antioxidant

Layer thickness 0.13mm

In Comparative Example 1, the maleic anhydride-modified EEA (20 parts by weight) of the inner layer in Example 1 was not added. Although the prescribed values were cleared for flexibility and tensile strength, the withstand voltage could not be satisfied. In addition, the comparative example 2 is the example which added the simple EEA which was not maleic anhydride modified instead of the maleic anhydride modified EEA of the inner layer in Example 1, and clears a prescribed value about flexibility and tensile strength similarly to the comparative example 1 However, the withstand voltage could not be satisfied.

From the above test results, by increasing the VA content of EVA, the base resin of the inner layer, the flexibility of the halogen-free flame-retardant wire can be ensured, and the breakdown voltage can be increased by adding maleic anhydride-modified ethylene ethyl acrylate copolymer. By lowering the VA content of EVA, which is the base resin of the outer layer, the surface of the halogen-free flame-retardant wire is made hard to prevent the wires from adhering to each other, while increasing the elongation and tensile strength of the low-elasticity body, thereby increasing the flexibility and withstand voltage. It can be set as a halogen-free flame-retardant wire provided with both.

In addition, by making the thickness of the outer layer of the electrical insulator thinner than the thickness of the inner layer, the above-described effect can be further improved.

1 is a view for explaining the outline of a halogen-free flame retardant wire according to the present invention.

Explanation of symbols for the main parts of the drawings

1: halogen-free flame retardant wire 2: electrical conductor

3: electrical insulator (inner layer) 4: electrical insulator (outer layer)

5: electrical insulator

Claims (2)

As a halogen-free flame retardant wire insulated from the outer circumference of the electrical conductor with an electrical insulator consisting of an inner layer and an outer layer, The inner layer is 5 to 40 parts by weight of maleic anhydride modified ethylene ethyl acrylate copolymer (maleic anhydride 1 to 40%) relative to 100 parts by weight of ethylene vinyl acetate copolymer having a vinyl acetate content of 60 to 80%. And metal hydroxides are added, The outer layer is a halogen-free flame-retardant electric wire, characterized in that the metal hydroxide is added to the ethylene vinyl acetate copolymer having a vinyl acetate content of 30% or more and less than 60%. The method of claim 1, The halogen-free flame-retardant electric wire, characterized in that the thickness of the outer layer is formed thinner than the thickness of the inner layer.

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