KR20110094885A - Composition for power cable sheath with high strength and high performance flame retardant - Google Patents

Abstract

PURPOSE: A sheath material composition is provided to ensure excellent tensile strength at high temperature and elongation after the heating. CONSTITUTION: A sheath material composition comprises 100 parts by weight of a base resin, 50-100 parts by weight of a flame retardant, and 1-10 parts by weight of red phosphorous flame-retarding aids. The base resin is a mixed resin in which 50-90 parts by weight of a linear low-density polyethylene resin having the melting point of 125 °C or more and 10-50 parts by weight of a reactive linear low-density polyethylene resin to which a polar group is introduced.

Description

Composition For Power Cable Sheath With High Strength And High Performance Flame Retardant

The present invention relates to sheath material compositions for power cables.

At present, one type of power cable used in Korea is shown in FIG. 1, with an inner semiconductive layer 2, an insulation layer 3, and an outer semiconducting layer centered on a conductor 1. 4, an outer semiconductive layer, a metallic shield 5 and a sheath layer 6. In order to secure the flame retardancy of the power cable, conventionally, a flame retardant paint is applied to the surface of the sheath layer, or an ethylene copolymer such as ethylene vinyl acetate (EVA) or ethylene ethyl acrylate (EEA) having good input properties of the flame retardant as the sheath material. The method of using was applied. However, the sheath body of the power cable manufactured by the above method has a low melting point, making it difficult to satisfy the heat resistance at high temperature, and also has a disadvantage of not satisfying the standard value of hardness required for the power cable sheath body.

In order to overcome the above disadvantages, a method of securing flame retardancy by adding an inorganic flame retardant to polyethylene as a sheath material has been devised. However, polyethylene, which is generally used as a sheath material, is a high-density polyethylene with a high density, and thus has high crystallinity. Therefore, even when a small amount of inorganic flame retardant is added, the mechanical properties of the sheath are greatly reduced.

The technical problem of the present invention is to provide a sheath material composition having not only excellent mechanical properties but also low heat distortion and high flame retardancy.

In order to achieve the above object, the sheath material composition for high strength and high flame retardant power cable of the present invention is 50 to 90 parts by weight of linear low density polyethylene resin having a melting point of 125 ° C. or higher and 10 to 50 reactive linear low density polyethylene resin having a polar group introduced therein. By weight of the blended mixed resin is used as the base resin, and includes 50 to 100 parts by weight of flame retardant and 1 to 10 parts by weight of flame retardant aid based on 100 parts by weight of the base resin.

The sheath body produced using the sheath material composition for high strength and high flame retardant power cables of the present invention is excellent in tensile strength, elongation rate and thermal stability as well as high flame retardancy and low smoke resistance. Therefore, the high strength and high flame retardance power cable can be manufactured using the sheath body manufactured in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings attached to the present specification illustrate exemplary embodiments of the present invention, and together with the detailed description of the present invention, the present invention is intended to help understand the technical idea of the present invention. No.
1 is a longitudinal sectional view of a power cable in the prior art.
2 is a longitudinal sectional view of a power cable of an embodiment according to the present invention.

Hereinafter, the present invention will be described in detail.

The sheath material composition for high strength and highly flame retardant power cables of the present invention comprises a conductor 11, an inner semiconducting layer 12, an insulating layer 13, an outer semiconducting layer 14, a metal shield 15, and the like as shown in FIG. The sheath layer 16 is used to form the sheath layer 16 of a power cable having a structure.

The sheath material composition of the present invention uses a mixed resin of 50 to 90 parts by weight of a linear low density polyethylene resin having a melting point of 125 ° C. or more and 10 to 50 parts by weight of a reactive linear low density polyethylene resin having a polar group introduced therein as the base resin. 50 to 100 parts by weight of the flame retardant and 1 to 10 parts by weight of the flame retardant adjuvant based on 100 parts by weight of the resin.

In the sheath material composition of the present invention, a linear low density polyethylene resin having a melting point of 125 ° C. or higher is used without using a linear low density polyethylene having a melting point of about 120 ° C. which is generally used. As a result, the sheath produced by the sheath material composition of the present invention is excellent in mechanical properties and heat resistance.

As the reactive linear low density polyethylene resin into which the polar group of the present invention is introduced, it is preferable to use a linear low density polyethylene resin grafted with maleic anhydride or glycidyl methacrylate.

In the present invention, magnesium hydroxide is used as the flame retardant, and preferably, magnesium hydroxide surface-treated with a polymer resin such as silane is used as the flame retardant. In addition, the flame retardant is preferably used in an amount of 50 to 100 parts by weight. This is because if the content is less than 50 parts by weight, the flame retardant properties of the sheath are lowered. If the content is more than 100 parts by weight, the mechanical properties of the sheath are lowered.

In the present invention, 1 to 10 parts by weight of an enemy is used as the flame retardant aid. If the content of the flame retardant aid is less than 1 part by weight, it is difficult to obtain the effect of high flame retardancy of the sheath, and if the content is more than 10 parts by weight, the mechanical properties of the sheath are not only degraded, but the appearance is also rough.

In addition, in the present invention, 1 to 10 parts by weight of the additive may be further included in the sheath material composition according to other purposes. As the additive, lubricants or antioxidants may be used alone or in combination.

The lubricant of the present invention means a material having properties that can maintain physical properties in a product state and improve processability. As the lubricant, any one or more selected from the group consisting of high molecular weight wax, low molecular weight wax, polyolefin wax, paraffin wax, paraffin oil, stearic acid and metal stearate may be selected and used.

As the antioxidant of the present invention, any one or more selected from the group consisting of amine-based, dialkyl ester-based, thioester-based and phenol-based antioxidants can be used.

Sheaths made using the sheath material compositions of the present invention can be used in the manufacture of high strength and highly flame retardant power cables.

[Example]

The present invention will be described in more detail with reference to the following Examples. The average person skilled in the art to which the present invention pertains may change the present invention in various other forms in addition to the embodiments described in the following examples, and the following examples merely illustrate the present invention, and the scope of the technical spirit of the present invention is given below. It is not to be construed as limiting the scope of the examples.

In order to examine the performance change according to the components of the sheath material composition for high-strength and high flame-retardant power cable of the present invention, the sheath material composition of Examples and Comparative Examples was prepared with the composition shown in Table 1 below. All units in Table 1 are parts by weight.

[Description of Components Used in Table]

Resin a: Linear low density polyethylene resin having a melting point of 125 ° C. or higher

Resin b: High density polyethylene resin (HDPE) with a density of at least 0.940 g / cm ³

Resin c: low density polyethylene resin (LDPE) with a density of 0.91 to 0.94 g / cm ³ and a melting point of about 110 ° C.

Resin d: Linear low density polyethylene resin having a melting point of about 120 ° C.

Resin e: Linear low density polyethylene resin grafted with maleic anhydride

Magnesium Hydroxide: Magnesium Hydroxide Surface-treated with Polymer Resin

Flame Retardant Supplements:

Antioxidant: Phenolic Antioxidant

Lubricant: metal stearate

Measurement and evaluation of physical properties

A sheath was manufactured using the sheath material composition according to the above Examples (1-4) and Comparative Examples (1-6), and a power cable having the sheath was produced by a conventional method. Table 2 shows the results of testing the mechanical properties, the heat deformation, and the flame retardance of each of the specimens obtained by slicing the sheath layer of the manufactured power cable and the comparative example. Brief experimental conditions are as follows.

㉠ mechanical properties

Tensile strength and elongation at room temperature were measured by mechanical test of the specimen (item 9 of IEC60811-1-1). Tensile strength at room temperature should be 12.5MPa or more and elongation should be 300% or more.

In addition, the elongation after heating at 110 ° C. for 240 hours should be at least 300%.

㉡ heating deformation

The heat deformation was measured by the heat deformation test of the specimen (clause 8 of IEC60811-3-1). The heat deflection should not exceed 50% when a 1.7 kg load is applied to a 5 mm thick specimen at 110 ° C.

㉢ flame retardant

Flame retardancy was measured by the flame retardancy test (IEC60332-1) of the specimen. Flame retardancy measurement method is as follows. After the flame has been applied to the specimen at a 45 degree angle for 60 seconds, the flame has been removed and the total burned length should not exceed 425 mm above and 65 mm below from the application point.

As summarized in Table 2, the specimens of Examples 1 to 4 satisfied the standard values in mechanical properties (tensile strength at room temperature, elongation at room temperature, elongation after heating), and heat deformation, and all passed the flame retardancy test.

The specimen of Comparative Example 1 satisfied the standard values in mechanical properties (tensile strength at room temperature, elongation at room temperature, elongation after heating) and heating deformation, but failed in the flame retardancy test. This result was due to the lack of flame retardant content, including 40 parts by weight of the flame retardant in the sheath material composition.

The specimen of Comparative Example 2 satisfies the criterion of heat deformation and passed the flame retardancy test, but did not satisfy the criterion of mechanical properties (tensile strength at room temperature, elongation at room temperature, elongation after heating). This result was due to the excessive content of the flame retardant including 120 parts by weight of the flame retardant.

The specimen of Comparative Example 3 satisfied the standard values in mechanical properties (tensile strength at room temperature, elongation at room temperature, elongation after heating) and heating deformation, but failed in the flame resistance test. This result was due to the lack of flame retardant content in the sheath material composition, including 0.5 parts by weight of flame retardant aids.

The specimen of Comparative Example 4 satisfies the criterion of heating deformation and the power cable including the sheath was passed in the flame retardancy test, but did not satisfy the criterion of mechanical properties (tensile strength at room temperature, elongation at room temperature, elongation after heating). It was. This result occurred because high density polyethylene resin was used instead of high melting point linear low density polyethylene resin. That is, the higher the density of the polyethylene resin, the less the amorphous region and the worse the mixing performance (Filler loading capacity), the mechanical properties of Comparative Example 4 using a high-density polyethylene resin was not good.

The specimen of Comparative Example 5 satisfies the mechanical properties (tensile strength at room temperature, elongation at room temperature, elongation after heating), and the power cable including the sheath was passed in the flame retardancy test, but it was broken in the test of the heat deformation and did not satisfy the reference value. I couldn't. This result was due to the use of a low density polyethylene resin having a low melting point (about 110 ° C.) rather than a high melting point linear low density polyethylene resin.

The specimen of Comparative Example 6 satisfied the mechanical properties (tensile strength at room temperature, elongation at room temperature, elongation after heating) and passed the flame retardancy test, but did not satisfy the criterion for the test of heat deformation. This result is due to the use of a general linear low density polyethylene resin having a low melting point (about 120 ° C.) without using a high melting point linear low density polyethylene resin.

From these results, it can be seen that the sheath prepared by the sheath material composition for the high strength and high flame retardant power cable of the present invention and the power cable having the same satisfy all reference values in mechanical properties, heat deformation, and flame retardancy. This result was obtained because a base resin containing a high melting point linear low density polyethylene resin was used, and a sheath material composition containing a base resin having a suitable composition ratio, a flame retardant, and a flame retardant aid.

As described above, optimal embodiments of the present invention have been disclosed. Although specific terms have been used in the specification including the present embodiment, it is only used for the purpose of describing the present invention to those skilled in the art in detail and used to limit the meaning or limit the scope of the present invention described in the claims. Make it clear.

Reference numerals used in the drawings of the present invention mean the following.
1, 11: conductor 2, 12: inner semiconducting layer
3, 13 insulation layer 4, 14 outer semiconducting layer
5, 15: metal shield 6, 16: sheath layer

Claims (7)

50 to 90 parts by weight of a linear low density polyethylene resin having a melting point of 125 ° C. or higher and 10 to 50 parts by weight of a reactive linear low density polyethylene resin having a polar group introduced therein are used as basic resins.
Per 100 parts by weight of the base resin,
50 to 100 parts by weight of a flame retardant; And
Sheath material composition for high-strength and high flame-retardant power cable comprising a; 1 to 10 parts by weight of a fire retardant auxiliary agent. The method of claim 1,
The reactive linear low density polyethylene resin having the polar group introduced therein is a linear low density polyethylene resin grafted with maleic anhydride or glycidyl methacrylate. The method according to claim 1 or 2,
The flame retardant is a sheath material composition for a high strength and high flame retardant power cable, characterized in that the magnesium hydroxide surface-treated with a polymer resin. The method of claim 3,
A sheath material composition for a high strength and highly flame retardant power cable further comprising 1 to 10 parts by weight of a lubricant or an antioxidant as an additive. The method of claim 4, wherein
Said lubricant is any one or more selected from the group consisting of high molecular weight wax, low molecular weight wax, polyolefin wax, paraffin wax, paraffin oil, stearic acid and metal stearate. The method of claim 4, wherein
The antioxidant is a sheath material composition for high-strength and high flame-retardant power cable, characterized in that any one or more selected from the group consisting of amine-based, dialkyl ester-based, thioester-based and phenolic antioxidants. Conductor;
An inner semiconducting layer surrounding the conductor;
An insulation layer surrounding the inner semiconducting layer;
An outer semiconducting layer surrounding the insulating layer;
A metal shield provided outside the outer semiconducting layer; And
A power cable comprising a sheath layer forming an outermost layer while surrounding an outer surface of the metal shield,
And the sheath layer is formed of the composition of claim 1.

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