KR101408925B1 - Light Weight Power Cable Using Semiconductive Composition And Insulation Composition - Google Patents

Abstract

 The present invention relates to a power cable including a conductor, an inner semiconductive layer surrounding the conductor, an insulating layer surrounding the inner semiconductive layer, and an outer semiconductive layer surrounding the insulating layer. More specifically, the inner semiconductive layer or the outer semiconductive layer may be formed of one kind selected from the group consisting of carbon nanotubes, carbon black, graphene, carbon nanotube-graphene hybrid composite and carbon nanotube-graphene- Wherein the insulating layer is formed by an insulating composition comprising a surface modified nanosinus particle and the finally produced power cable is formed by a semiconductive composition comprising a mixture of two or more species, , Hot set, and the like. In addition, the dielectric breakdown strength is high and the protrusion size is reduced compared with the conventional one, so that the power cable can be lightened.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a lightweight power cable using a semiconductive composition and an insulating composition,

The present invention relates to a lightweight power cable including an inner semiconductive layer of excellent quality, an insulating layer and an outer semiconductive layer.

As natural resources are depleted, while demand for electric power is further increased and regulations for eco-friendliness are strengthened, the development of electric power cables is aimed at transferring high-capacity energy, reducing weight, and reducing energy loss. The weight reduction of the power cable can be achieved by reducing the diameter of the cable as the thickness of the insulating layer is reduced. Accordingly, the manufacturing cost can be reduced, and the distribution cost and the construction cost can be drastically reduced. However, as the thickness of the insulating layer of the power cable is reduced, there may be a problem that the electric current is reduced as the allowable current (Ampacity) flowing through the cable is reduced or the dielectric breakdown strength is lowered.

In addition, the content of carbon black contained in the conductive composition generally used for the production of the inner semiconductive layer of the power cable, or the outer semiconductive layer, was added in large amounts to the base resin. The volume and weight of the power cable thus produced are increased, and the dispersibility between the base resin and the carbon black is lowered, resulting in the formation of large projections.

It is an object of the present invention to provide a lightened power cable having an insulating layer having a high dielectric breakdown strength and a semiconductive layer having a reduced projection size.

In order to achieve the above object, a lightweight power cable of the present invention comprises a conductor, an inner semiconductive layer surrounding the conductor, an insulating layer surrounding the inner semiconductive layer, and an outer semiconductive layer surrounding the insulating layer. The inner semiconductive layer or the outer semiconductive layer is formed by mixing 1 to 15 parts by weight of a mixture of 100 parts by weight of a polyolefin base resin with a mixture of carbon nanotubes alone or a carbon nanotube selected from carbon black and graphene Wherein the insulating layer is formed of at least one kind selected from the group consisting of nano-inorganic particles 0.5 of surface modified with respect to 100 parts by weight of a base resin composed of at least one selected from the group consisting of low density polyethylene (LDPE), ultra high molecular weight polyethylene (UHMW-PE) and thermoplastic polypropylene To 10 parts by weight of the composition.

The lightweight electric power cable of the present invention can exhibit excellent effects in physical properties such as volume ratio resistance, hot set, tensile strength and elongation ratio required for a power cable, and also has a high insulation breakdown strength and a reduced projection size . Therefore, even when an insulator having a reduced thickness compared to the prior art is applied, the allowable current can be transmitted to the same extent as in the conventional case, so that the power cable can be reduced in weight.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. No.
1 is a SEM photograph of a cross section of a specimen of Example 7. Fig.
2 is a SEM photograph of a cross section of the specimen of Example 8. Fig.
3 is a SEM photograph of a cross section of the specimen of Example 9. Fig.
4 is a SEM photograph of a cross section of a specimen of Comparative Example 4. Fig.
5 is a SEM photograph of a cross section of a specimen of Comparative Example 5.
6 is a SEM photograph of a cross section of a specimen of Comparative Example 6. Fig.

Hereinafter, the present invention will be described in detail.

The lightweight power cable includes a conductor, an inner semiconductive layer surrounding the conductor, an insulation layer surrounding the inner semiconductive layer, and an outer semiconductive layer surrounding the insulation layer, wherein the inner semiconductive layer or the outer semiconductive layer comprises a carbon nanotube , Carbon black, graphene, a carbon nanotube-graphene hybrid composite, and a carbon nanotube-graphene-carbon black hybrid composite, to a semiconductive composition comprising a mixture of at least one selected from the group consisting of carbon black, And the insulating layer is formed by an insulating composition comprising surface modified nanosinorganic particles.

Wherein the semiconductive composition is a mixture of 100 parts by weight of a polyolefin base resin and 1 part by weight of a carbon nanotube, carbon black, graphene, carbon nanotube-graphene hybrid composite and carbon nanotube-graphene- And 1 to 15 parts by weight of a mixture of two or more species. When the amount is less than 1 part by weight, problems such as required volume resistivity can not be satisfied. When the amount is more than 15 parts by weight, workability and reproducibility such as dispersibility and extrudability are lowered Lt; / RTI >

When the semiconductive composition of the present invention contains carbon nanotubes, the movement of the carbon nanotube particles becomes more active as the temperature rises, so that the adjacent distance between the carbon nanotube particles becomes closer to cause a reduction in the volume ratio resistance, . In addition, when the semiconductive composition of the present invention contains carbon nanotubes, it is possible to reduce the content of carbon black. As a result, it is possible to reduce the extrusion load by improving the flow rate of the semiconductive composition And can exhibit the extrudability. As the extrudability improves, the process time can be shortened and a cost saving effect can be expected.

The graphene refers to a material having a structure in which 20 layers or less of graphite are laminated. In the present invention, graphene particles having a thickness of 30 nm or less and a diameter of 10 micrometers or less are used. When the semiconductive composition of the present invention contains a small amount of graphene, not only the electrical properties are improved but also the mechanical properties at room temperature and high temperature are enhanced, which is advantageous, and the thermal conductivity and the glass transition temperature of the base resin are increased Whereby a highly reliable semiconductor layer can be manufactured.

Since the semiconductive composition of the present invention contains carbon nanotubes and / or graphene, the content of carbon black can be remarkably lowered compared with the prior art using only carbon black as semi-conductive particles, have. Since the carbon black particles have a high specific surface area of 40 to 200 m ² / g, even if the content of the carbon black is slightly reduced, the carbon black particles can exhibit an improved effect in terms of compounding, mixing rate, volume resistivity, extrudability and reproducibility So that the scorch volume can be reduced. Accordingly, in the present invention, it is possible to produce a smooth semiconductive layer by using no carbon black or using a small amount less than 15 parts by weight based on 100 parts by weight of the base resin. As a result, it is possible to reduce the thickness of the insulating layer, to provide a lightweight power cable, and to reduce the cost of logistics and construction of the power cable.

The semiconductive composition may further comprise 0.1 to 1 part by weight of an antioxidant. As such an antioxidant, amines and derivatives thereof, phenols and derivatives thereof, or reaction products of amines and ketones may be used alone or in combination of two or more. In order to improve the heat resistance, one or more kinds of reactants of diphenylamine and acetone, zinc 2-mercaptobenzimidazoate and 4,4'-bis (?,? - dimethylbenzyl) Can be used in combination. Also, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxy-phenyl) -propionate], pentaerythritol-tetrakis- (beta -lauryl-thio) propionate , 2,2'-thiodiethylene bis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate], distearyl- Ester may be used singly or in combination of two kinds.

As the polyolefin used as the base resin of the semiconductive composition, ethylene ethyl acrylate (EEA), ethylene butyl acrylate (EBA) or the like may be used singly or copolymerized with ethylene ethyl acrylate -Ethylene butyl acrylate copolymer may be used. Preferably, the melt index (MI) of the base resin is from 1 to 50.

In addition, the insulating composition of the present invention comprises 0.5 to 10 parts by weight of the surface-modified nano-inorganic particles per 100 parts by weight of the base resin. With respect to the above numerical range, when it is contained in an amount of less than 0.5 part by weight, the effect of reducing space charge is exerted, but the AC and DC dielectric breakdown strength is relatively low. When it is contained in more than 10 parts by weight, It degrades sex.

The nano-inorganic particles may be nano-sized silica, titanium oxide, or magnesium oxide alone or in combination of two or more. Preferably, the nano-inorganic particles are surface-modified with vinylsilane, stearic acid, oleic acid, aminopolysiloxane, and the like. In particular, when surface modified silica is used, excellent AC dielectric breakdown strength can be expected for AC power cable, and excellent DC dielectric breakdown strength can be expected for DC power cable when surface modified magnesium oxide is used.

Typically, oxides such as silica, titanium oxide, and magnesium oxide are hydrophilic with high surface energy while base resins such as low density polyethylene (LDPE), ultra high molecular weight polyethylene (UHMW-PE), and thermoplastic polypropylene have low surface energy There is a problem that the dispersibility of the nano-inorganic particles with respect to the base resin is poor and the electrical characteristics are adversely affected. Therefore, in order to solve such a problem, it is preferable to modify the surface of the nano-inorganic particles. When the nano-inorganic particles are not surface-modified, gaps are formed between the nano-inorganic particles and the base resin, thereby deteriorating the mechanical properties and lowering the electrical insulation properties such as the dielectric breakdown strength.

Preferably, the nano-inorganic particles of the present invention are surface-modified with vinyl silane to exhibit better dispersibility with respect to the base resin, effectively suppressing the movement of the charge carriers, and exhibiting improved electrical characteristics. A hydrolyzate of vinylsilane is chemically bonded to the surface of the nano-inorganic particle by a condensation reaction to form a surface-modified nano-inorganic particle. Thereafter, the silane group of the nanosilicone particles surface-modified with the vinyl silane reacts with the base resin to ensure excellent dispersibility. For such dispersibility, the nano-inorganic particles of the present invention have an average particle diameter of about 500 nm or less, and preferably an average particle diameter of about 100 nm or less.

The silica has a purity of 99% or more and 100% or less and a surface area (BET) of 30 to 400 m ² / g and may have an amorphous structure. The magnesium oxide has a purity of 99% or more and 100% or less, and may have a single crystal or polycrystal form.

The insulating composition may include 1 to 5 parts by weight of a crosslinking agent based on 100 parts by weight of the base resin. As such a crosslinking agent, diacylperoxide and the like may be used. When the amount of the crosslinking agent is less than 1 part by weight, sufficient cross-linking does not occur. Therefore, the mechanical properties of the semiconductive layer may be lowered. When the amount of the crosslinking agent is more than 5 parts by weight, Excessive crosslinking byproducts may occur and the volume resistivity of the semiconductive layer may deteriorate.

The insulating composition may further include 0.1 to 0.5 parts by weight of an antioxidant based on 100 parts by weight of the base resin. As the antioxidant, tetrakis (2,4-di-t-butylphenyl) Rendipoite and the like can be used.

(LDPE), ultrahigh molecular weight polyethylene (UHMW-PE), and thermoplastic polypropylene may be used alone or as a mixture of two or more thereof as the base resin of the insulating composition. The polypropylene may be a low density polyethylene (LDPE), a linear low density polyethylene Polyethylene (LLDPE), and C4 to C8 alpha olefins.

[Example]

Hereinafter, the present invention will be described more specifically by way of examples. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims and their equivalents. It should not be construed as an intention to limit the scope to example.

≪ Examples 1 to 6 and Comparative Examples 1 and 2 >

Compositions of Examples and Comparative Examples were prepared with the composition shown in Table 1 below in order to examine the performance change depending on the composition of the semiconductive composition used to produce the lightweight power cable of the present invention. The unit of the content of each component in Table 1 is parts by weight.

Semiconductivity
Composition ingredient
Example Comparative Example One 2 3 4 5 6 One 2 Base resin 100 100 Carbon nanotubes 5 4 4 4 3.5 3 - - Carbon black - 5 10 - - - 28 33 Grapina - - - 0.15 0.5 One - - Antioxidant 0.4 0.4

[Description of components used in the table]

* Base resin: Ethylene ethyl acrylate-ethylene butyl acrylate copolymer

* Antioxidants: 4,4'-bis (?,? - dimethylbenzyl) diphenylamine

Measurement and evaluation of physical properties

Using the semiconductive compositions according to Examples (1) to (6) and Comparative Examples (1) and (2), semi- conductor specimens were prepared. The volume resistivity, the room temperature tensile strength, the room temperature elongation and the hot set were measured for the thus obtained Examples and Comparative Examples, and the results are summarized in Table 2 below. The brief experimental conditions are as described below.

㉠ Volume ratio resistance

The volume resistivity (? 占) m) at 25 占 폚 and 90 占 폚 at a direct current application voltage of 10 V was measured for the entire sample of the semiconductor device.

㉡ Tensile strength at room temperature

The dog-bone type semi-conductor specimens were prepared according to ASTM D412, and the tensile strength at room temperature was measured using a UTM 5566 instrument.

㉢ Room temperature elongation

The dog bone type semi-conductor specimens were prepared according to ASTM D412, and the room temperature elongation was measured using a UTM 5566 instrument.

㉣ Hot set

The hot set test for the half-width specimens was carried out with a tensile test specimen at 150 ° C for 15 minutes and then evaluated with IECA T-562.

Test Items Bulk specific resistance (Ω · cm) Room temperature tensile strength
(Kgf / mm ² ) Room Temperature Elongation (%)
Hot set (%)
25 ℃ 90 ° C Example 1 419.3 107.3 1.91 420 60 Example 2 489.5 210 1.85 412 70 Example 3 430.5 130 1.82 380 65 Example 4 390.5 98.4 2.13 420 59 Example 5 375.4 100.9 2.43 435 61 Example 6 390.8 102.6 2.74 415 57 Comparative Example 1 482.40 120000 1.61 424 90 Comparative Example 2 35 1244 1.43 309 90

As a result of measuring the semiconducting properties as summarized in Table 2, the specimens prepared using the semiconductive compositions of Examples 1 to 6 satisfied the standard values in volume ratio resistance, room temperature tensile strength, room temperature elongation and hot set.

However, the specimens prepared using the semiconductive compositions of Comparative Examples 1 and 2 did not satisfy the volume resistivity at 90 캜. These results are attributed to the fact that the semiconductive compositions of Comparative Examples 1 and 2 did not contain carbon nanotubes but contained a large amount of carbon black.

≪ Examples 7 to 9 and Comparative Examples 3 to 6 >

In order to examine the performance change depending on the composition of the insulating composition used for manufacturing the light-weight power cable of the present invention, compositions of Examples and Comparative Examples were prepared with the compositions shown in Table 3 below. The unit of the content of each component in Table 3 is parts by weight.

Isolation
Composition
ingredient Example 7 Example 8 Example 9 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Base resin 100 100 Silica
Surface modification One 3 5 - - - - Untreated - - - - One 3 5 Cross-linking agent 2 2 Antioxidant 0.5 0.5

[Description of components used in the table]

* Base resin: Low density polyethylene (LDPE)

Surface-modified silica: Silica surface-modified with vinylsilane

* Crosslinking agent: Dicumylperoxide

Antioxidants: tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenylene diphosphite

Measurement and evaluation of physical properties

A master batch compound was prepared using the insulating material compositions according to Examples 7 to 9 and Comparative Examples 3 to 6 and a twin screw extruder having a screw diameter of 25 mm (L / D = 60) Was used for the extrusion process. The thus prepared insulator was hot-pressed to prepare a 0.5 mm thick specimen for measuring the AC dielectric breakdown strength, and the AC insulation breakdown strength (ASTM D149) was tested. The results are summarized in Table 4 below. The brief experimental conditions are as follows. SEM photographs of cross sections of the specimens of Examples 7 to 9 are shown in FIGS. 1 to 3, respectively, and SEM pictures of cross sections of the specimens of Comparative Examples 3 to 6 are shown in FIGS. 4 to 6, respectively.

㉠ Mean AC insulation breakdown strength (average AC BDV)

The AC breakdown strength (kV / mm) was measured at 90 ° C for the insulator specimens, and the average AC breakdown strength (average AC BDV) was measured at the weave distribution.

교 AC insulation breakdown strength at 1% failure (1% E AC BDV)

The AC breakdown strength (1% E AC BDV) was measured for 1% fracture of the specimen in the Weibull distribution while measuring the AC breakdown strength (kV / mm) at 90 ° C for the insulator specimen. The 1% E AC BDV means that dielectric breakdown occurs at 99% of the specimen above a value of 1% E AC BDV.

Further, as a result of the measurement of the insulation properties as summarized in Table 4, the specimens prepared using the insulating compositions of Examples 7 to 9 of the present invention showed excellent dielectric breakdown characteristics. That is, the specimens of Examples 7 to 9 of the present invention using silica modified with vinylsilane showed excellent electrical insulation characteristics, and particularly, the electrical insulation characteristics of the specimen of Example 8 were more excellent.

However, the specimens prepared using the insulating compositions of Comparative Examples 3 to 6 did not contain silica or had insufficient dielectric breakdown properties including general surface-treated silica.

As described above, the optimal embodiments of the present invention have been disclosed. Although specific terms have been employed in the specification to include those embodiments, it will be understood that they have been used only for the purpose of describing the invention to those of ordinary skill in the art and are intended to limit the scope of the invention as defined in the claims Or not.

Claims (6)

A power cable comprising a conductor, an inner semiconductive layer surrounding the conductor, an insulating layer surrounding the inner semiconductive layer, and an outer semiconductive layer surrounding the insulating layer,
The inner semiconductive layer or the outer semiconductive layer is formed by mixing 1 to 15 parts by weight of a mixture of 100 parts by weight of a polyolefin base resin with a mixture of carbon nanotubes alone or a carbon nanotube selected from carbon black and graphene Lt; / RTI >
Wherein the insulating layer comprises 0.5 to 10 parts by weight of surface modified nano-inorganic particles per 100 parts by weight of a base resin comprising at least one selected from the group consisting of low density polyethylene (LDPE), ultrahigh molecular weight polyethylene (UHMW-PE) and thermoplastic polypropylene ≪ RTI ID = 0.0 > 1, < / RTI > delete The method according to claim 1,
Wherein the semiconductive composition further comprises 0.1 to 1 part by weight of an antioxidant. delete The method according to claim 1,
Wherein the insulating composition comprises, based on 100 parts by weight of the base resin,
1 to 5 parts by weight of a crosslinking agent, and
And 0.1 to 0.5 parts by weight of an antioxidant. 6. The method of claim 5,
Wherein the nano-inorganic particles are at least one selected from the group consisting of silica, titanium oxide, and magnesium oxide.

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