KR101457799B1 - Power cable having a semiconductive layer - Google Patents

Abstract

The present invention relates to a power cable including a semiconductive layer. The power cable according to an embodiment of the present invention includes: at least one conductor; an internal semiconductive layer surrounding the conductor; and an insulating layer surrounding the internal semiconductive layer. The semiconductive layer of the power cable has excellent surface attributes including high surface smoothness.

Description

Technical Field The present invention relates to a power cable having a semiconductive layer,

The present invention relates to a power cable having a semiconductive layer. Specifically, the present invention relates to a power cable having a semiconductive layer having excellent mechanical properties such as surface smoothness as well as mechanical and electrical properties.

Generally, a power cable for high voltage or ultrahigh voltage can be formed in the order of an inner semiconductive layer, an insulating layer, an outer semiconductive layer, a sheath layer, and the like around a conductor. Particularly, the inner semiconductive layer improves the degree of interfacial surface between the conductor and the insulating layer during cable production, suppresses formation of an air layer therebetween, forms a gradient of insulation resistance, and alleviates local field concentration Function. In addition, the outer semiconductive layer performs a function of shielding the cable, and performs an equal electric field on the insulating layer. That is, the inner semiconductive layer and the outer semiconductive layer (hereinafter, referred to as a semiconductive layer) perform a very important function in terms of reinforcing the electrical and mechanical properties of the cable and hence the service life.

As disclosed in related U.S. Patent Application Publication No. 2010-0206607, the semiconductive layer generally includes a conductive material such as metal particles, carbon black, etc. to perform local field concentration mitigation, shielding function and the like in the cable. In addition, since the conductive materials are generally nano-sized fine particles and tend to entanglement with each other in the base resin constituting the semiconductive layer, they are connected to each other in the base resin to form a conductive network In order to exhibit the semi-conductive characteristics of the semiconductive layer by forming a relatively large amount, for example, in an amount of about 40 to 60% by weight based on the total weight of the semiconductive layer.

However, the conductive material included in the substantial amount may cause surface irregularities such as protrusions on the surface of the semiconductive layer to be formed, thereby reducing the surface smoothness of the semiconductive layer, thereby forming a void space between the semiconductive layer and the insulating layer, Concentration, shielding performance, and the like. The lowering of the surface properties of the semiconductive layer is caused by the fact that the base resin constituting the semiconductive layer can contain the filler such as a conductive material added thereto in a uniformly dispersed form, that is, the poorer the filler loading property In the case of using a base resin which is more prominent and which has excellent filling material loading property, there may be a problem that the bond strength between the base resin and the base resin is deteriorated due to the heterogeneity with the base resin constituting the insulating layer in contact with the semiconductive layer.

In this connection, U.S. Patent No. 7,982,537 discloses a conductive polymer composite material comprising a carbon nano tube as a conductive material. The carbon nanotubes have a shape having a large aspect ratio, for example, a length of 500 to 3,000 times the diameter of the cross section, so that the carbon nanotube has a relatively small amount of content So that the conductive network can be formed.

However, since the carbon nanotubes have a large aspect ratio as described above, they are entangled with each other in a base resin constituting the semiconductive layer and are difficult to disperse. In addition, when carbon nanotubes are connected, There is a problem that the contact area connected due to the diameter of the nanosize of the tube is extremely small and the contact resistance is increased, thereby deteriorating the anti-conduction characteristic.

In addition, although U.S. Published Patent Application No. 2013-0037759 discloses a technique using a combination of a graphene nanoplate and carbon black as a conductive material, there is a limit in reducing the content of the conductive material, Further improvement is required in terms of improving the smoothness of the surface of the whole layer.

Therefore, there is a demand for a new conductive material and a method for producing the conductive material, which can form a sufficient conductive network and realize semi-conductive property even with a small amount of content and does not deteriorate surface characteristics such as surface smoothness of a semiconductive layer to be produced.

It is an object of the present invention to provide a power cable including a semiconductive layer having sufficient semi-conductive properties by including a conductive filler having excellent electrical characteristics.

It is another object of the present invention to provide a power cable including a semiconductive layer having a sufficient semiconducting property and excellent surface smoothness even though the conductive filler is contained in a small amount compared to the conventional art.

In order to solve the above problems,

One or more conductors; An inner semiconductive layer surrounding the conductor; And an insulating layer surrounding the inner semiconductive layer, wherein the inner semiconductive layer comprises carbon nanotubes (CNTs) connected to each other through a bond by a line contact with the base resin and the conductive particles. carbon nano tubes). < RTI ID = 0.0 > [0002] < / RTI >

Wherein the conductive particles have the shape of a flake or a plate.

The conductive particles may be at least one selected from the group consisting of a metal flake, a metal plate, a carbon nano flake (CNF), and a carbon nano plate (CNP) Wherein the conductive particles are conductive particles.

On the other hand, the conductive particles and the carbon nanotubes (CNTs) may have a structure in which the surface of the conductive particles and the carbon nanotubes (CNT) have a structure in which 1 is selected from the group consisting of a hydroxyl group (-OH), an amine group (-NH ₂ ), a carboxyl group (-COOH) and an epoxy group Wherein the functional group is a silane coupling agent of vinyltrimethoxysilane, methyltrimethoxysilane, aminopropyltrimethoxysilane, or derivatives thereof; Polyhydric alcohol binders of ethylene glycol, propylene glycol, glycerin, or derivatives thereof; And a polycarboxylic acid bonding agent of oxalic acid, propanedioic acid, butane diacid, or a derivative thereof. The present invention also provides a power cable.

The present invention also provides a power cable, wherein the base resin is ethylene ethyl acrylate (EEA), ethylene butyl acrylate (EBA), or a combination thereof.

The power cable is characterized in that the base resin and the base resin constituting the insulating layer are the same base resin.

Here, the power cable is characterized in that the base resin is low density polyethylene (LDPE).

On the other hand, the content of the conductive filler is 0.5 to 20% by weight based on the total weight of the semiconductive composition.

Here, the content of the conductive filler is 2 to 10% by weight based on the total weight of the semiconductive composition.

The weight ratio of the carbon nanotube (CNT) to the conductive filler is 80:20 to 70:30.

Also, the content of the binder is 1 to 20 parts by weight based on 100 parts by weight of the conductive filler.

On the other hand, the conductive filler is introduced into the particle surface of the base resin.

Further, the semiconductive composition further comprises 0.1 to 4 parts by weight of a crosslinking agent based on 100 parts by weight of the base resin.

Further, the semiconductive composition further comprises 0.5 to 2 parts by weight of a lubricant, 0.5 to 2 parts by weight of an antioxidant and 1 to 20 parts by weight of a surfactant based on 100 parts by weight of the base resin. Cable.

The power cable further includes an outer semiconductive layer surrounding the insulating layer and a sheath layer surrounding the outer semiconductive layer.

On the other hand, one or more conductors; An inner semiconductive layer surrounding the conductor; And an insulation layer surrounding the inner semiconductive layer, wherein the inner semiconductive layer is made from a semiconductive composition comprising a base resin and a conductive filler, wherein the semiconductive composition is formed by the addition of the conductive filler The volume resistivity is 1 x 10 ³ to 1 x 10 ¹¹ ? Cm, and the viscosity is a value measured at a melting temperature and a fixed shear rate of ¹ x 10 ² s ^-1 of the base resin. , And power cable.

Here, the semiconductive composition has a viscosity increased by the addition of the conductive filler of 2,000 to 3,000 Pa · s, and the viscosity is a value measured at a melting temperature and a fixed shear rate of ¹ × 10 ² s ^-1 of the base resin Characterized in that it provides a power cable.

Also, the conductive filler includes carbon nanotubes (CNTs) connected to each other through a bond by line contact with the conductive particles.

1 is a cross-sectional view schematically showing a cross-sectional structure of a power cable according to the present invention.
2 is a longitudinal sectional view schematically showing a cross-sectional structure of a power cable according to the present invention.
FIG. 3 shows a state in which carbon nanotubes (CNTs) are connected when a conductive network is formed by conductive fillers in a base resin, and carbon nanotubes (CNTs) are connected to a line contact FIG. 1 is a schematic view showing a state in which the two electrodes are connected to each other via a coupling by a coupling.
FIG. 4 is a graph showing the relationship between the carbon nanotubes (CNTs) (carbon nanotubes (CNTs), carbon nanotubes (CNTs), and the like) connected to each other via a bond by line contact with a carbon nanoplate ) And a carbon nanoplate (CNP) in a weight ratio of 70:30).
FIG. 5 is a cross-sectional view of a carbon nanotube (CNT) (carbon nanotube (CNT)) bonded to ethylene ethyl acrylate (EEA) as a base resin through a bond by a line contact with a carbon nanoplate ) And carbon nanoplate (CNP) in a weight ratio of 80:20).
6 is an optical microscope picture of a sample sheet made from the semiconductive composition according to Example 2. Fig.
7 is an optical microscope photograph of a sample sheet made from the semiconductive composition according to Comparative Example 2. Fig.

1 and 2 show an embodiment of a power cable according to the present invention.

1 and 2, a power cable according to the present invention includes a conductor 1 made of a conductive material such as copper or aluminum, an insulating layer 3 made of an insulating polymer, (3), thereby suppressing partial discharge at the interface with the conductor (1), eliminating the air layer between the conductor (1) and the insulating layer (3) An outer semiconductive layer 4 serving as a shielding function of a cable and a function of applying an electric field uniform to the insulating layer 3, a sheath layer 5 for protecting the cable, And the like.

The insulating layer 3 may be manufactured from an insulating composition containing a polymer as a base resin. The polymer constituting the base resin is mostly an electrically insulating material, so there is no particular limitation. For electricity to pass, there must be free electrons, such as ions or metals, that can move positive electrons and electrons, because polymers are substances that are made up of covalent bonds between carbons and thus have little ability.

In general, the base resin forming the insulating layer 3 of the high-voltage or ultra-high-pressure cable is a polyolefin such as polyethylene (PE), polypropylene (PP), or ethylene propylene rubber (EPR) Can be used.

The polyethylene (PE) may comprise an ethylene homopolymer and / or a copolymer of ethylene and an? -Olefin such as propylene, 1-butene, 1-pentene, 1-hexene or 1-octene. Here, the ethylene copolymer may be a random copolymer or a block copolymer. The polyethylene may also comprise ultra low density polyethylene, low density polyethylene, linear low density polyethylene, high density polyethylene, or mixtures thereof.

The polypropylene (PP) may include a propylene homopolymer and / or a copolymer of propylene and an? -Olefin such as ethylene, 1-butene, 1-pentene, 1-hexene or 1-octene. Here, the propylene copolymer may be a random copolymer or a block copolymer.

On the other hand, the polyethylene (PE) and the polypropylene (PP) may be non-crosslinked or crosslinked resins. Here, the cross-linked polyethylene and the cross-linked polypropylene can be produced by a silane or an organic peroxide such as, for example, dicumyl peroxide (DCP) as a cross-linking agent. However, the crosslinked polyethylene and the crosslinked polypropylene have a disadvantage in that the mechanical properties of the cable are excellent, but they are difficult to recycle, and when the crosslinking or scorch occurs early in the production of the insulating layer, And the crosslinked byproducts such as acetophenone and alpha methylstyrene can facilitate accumulation of space charge in the insulating layer. Therefore, the insulating layer can be manufactured in consideration of the pros and cons of the crosslinked or uncrosslinked base resin depending on the use of the cable.

In the present invention, the semiconductive layer (2, 4) can be produced from a semiconductive composition comprising a base resin and a conductive filler.

The base resin may be appropriately selected from among conventionally used base resin for semiconductive layer, and examples thereof include polyolefins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene and polypropylene or polyolefins such as ethylene vinyl acrylate, ethylene ethyl acrylate But are not limited to, olefin copolymers such as ethylene oleate (EEA) and ethylene butyl acrylate (EBA), polyacrylates, polyesters, polycarbonates, polyurethanes, polyimides, polystyrenes and mixtures thereof.

Since the base resin of the conventional semiconductive composition should contain conductive material in an amount of usually 40 to 60 parts by weight based on 100 parts by weight of the base resin, it is preferable to use ethylene ethyl acrylate (EEA), ethylene butyl acrylate (EBA) have been used. However, these olefin copolymers have insufficient compatibility with the base resin for the insulating layer and insufficient bonding force, so that void spaces are generated between the insulating layer 3 and the semiconductive layers 2 and 4, The electric field is concentrated in the void space, and the problem of insulation breakdown and shortening of cable life can be caused.

On the other hand, since the semiconductive composition according to the present invention can realize a sufficient conductive network and semi-conductive property even when only a small amount of conductive filler is contained, the filling property is lower than that of the conventional olefin copolymer, A low-density polyethylene (LDPE) having excellent compatibility and bonding strength can be used.

The conductive filler may be selected from the group consisting of conductive particles, preferably conductive particles in the form of flakes or plates, such as metal flakes, metal plates, carbon nano- carbon nanotubes (CNTs) connected to each other through a line-by-line bond with conductive particles such as carbon nanotubes (CNTs), carbon nanotubes (CNTs), carbon nanotubes (CNTs)

As a result, the conductive filler maximizes the contact area between the carbon nanotube (CNT) and the other conductive particles to minimize the contact resistance at the contact surface, thereby achieving sufficient conductive network formation and anti-conduction characteristics with a small amount of conductive filler And it is also possible to avoid the conventional problems when a large amount of conductive filler is used, that is, a decrease in surface smoothness of the semiconductive layer.

In addition, since the filler loading property of the semiconductive layer (2, 4) base resin is not greatly taken into account by the use of a small amount of the conductive filler, the filler can be easily loaded and used as a base resin for a conventional semiconductive layer (EEA), ethylene butyl acrylate (EBA), and the like, and the filling material loadability is somewhat lower than these. However, in the case of using a base resin for the insulating layer 3, for example, a crosslinked polyethylene (XLPE) It is possible to use a base resin having excellent adhesion and bonding strength.

FIG. 3 is a view showing a state in which only conventional carbon nanotubes (CNTs) are connected to each other in the formation of a conductive network in the base resin, and line contact (carbon nanotubes (CNF), carbon nanoplate (CNTs) connected to each other through a bond by a line contact (CNT).

As shown in FIG. 3, when conventional carbon nanotubes (CNTs) are connected to each other, an increase in contact resistance due to point contact is caused to occur, so that sufficient anti-conduction characteristics can not be realized. On the other hand, CNTs are connected to each other via a line contact with other conductive particles, a decrease in contact resistance and a sufficient anti-conduction characteristic can be realized by increasing the contact area at the bonding site.

The carbon nanotubes (CNTs) are hexagons having six carbon atoms connected to each other to serve as tubes, and may have a single wall or a multiwall structure. Here, the carbon nanotube (CNT) may have a diameter of 20 to 200 nm, preferably 50 to 100 nm, and the length may be 10 to 50 μm, preferably 20 to 40 μm, no. The carbon nanotubes (CNTs) can be prepared by a known method, for example, but not limited to, the carbon nanotube production apparatus disclosed in U.S. Patent No. 5,916,642.

The other conductive particles such as a metal flake, a metal plate, a carbon nanoflake (CNF), and a carbon nanoplate (CNP) each have a thickness of 0.5 to 25 탆, preferably 1 to 10 탆, more preferably 2 to 5 탆 And a thickness of 10 to 100 nm, preferably 10 to 50 nm, more preferably 20 to 30 nm, but is not limited thereto.

The carbon nanotube (CNT) and the other conductive particles may have a functional group such as a hydroxyl group (-OH), an amine group (-NH ₂ ), a carboxyl group (-COOH), and an epoxy group (-O-). These functional groups may be produced in the synthesis of carbon nanotubes (CNTs) or the like, and may be introduced by an additional process after synthesis. These functional groups include silanes such as vinyltrimethoxysilane, methyltrimethoxysilane, aminopropyltrimethoxysilane, or derivatives thereof; Polyhydric alcohols such as ethylene glycol, propylene glycol, glycerin, or derivatives thereof; And a polycarboxylic acid such as oxalic acid, propanedioic acid, butane diacid, or a derivative thereof, to thereby bond the carbon nanotube (CNT) with the other carbon filler .

Here, the content of the binder may be 1 to 20 parts by weight, preferably 5 to 15 parts by weight, based on 100 parts by weight of the conductive material including the carbon nanotube (CNT) and the other conductive particles. When the content of the binder is less than 1 part by weight, the chemical bond between the carbon nanotube (CNT) and the other conductive particles may be insufficient. When the content of the binder is more than 20 parts by weight, the carbon nanotube (CNT) The electrical characteristics of the semiconductive layer (2, 4) may be lowered due to excessive chemical bonding between the carbon nanotubes (CNTs).

The weight ratio of the carbon nanotube (CNT) to the other conductive particles may be, for example, 90:10 to 10:90, preferably 80:20 to 50:50, and more preferably 80:20 to 70:30 have. When the weight ratio is less than 10:90, a large amount of conductive filler should be used in order to realize a sufficient semi-conductive property, and thus the surface smoothness of the semiconductive layer (2,4) may be lowered, whereas when the weight ratio is more than 90:10 There is a problem that the bonding between the carbon nanotubes (CNT) and the other conductive particles is insufficient and the manufacturing cost is increased due to the high content of carbon nanotubes, which are expensive compared to other conductive particles.

In this connection, FIG. 4 is a cross-sectional view of a carbon nanotube (CNT) (carbon (C)) bonded to ethylene ethyl acrylate (EEA) as a base resin through a bond by a line contact with a carbon nanoplate And 3 wt% of a carbon nanotube (CNT) and a carbon nanoplate (CNP) in a weight ratio of 70:30). FIG. 5 is a graph showing electron micrographs of a carbon nanotube (CNT) (CNP) is 80:20. FIG. As shown in FIGS. 4 and 5, it can be confirmed that carbon nanotubes (CNTs) connected to each other through a bond by a line contact with a carbon nanoplate (CNP) are uniformly dispersed in the base resin .

There is no particular limitation on the method for producing the conductive filler formed by connecting the carbon nanotubes (CNTs) to each other via the connection by line contact with other conductive particles. For example, the conductive filler may be formed by mixing the carbon nanotubes (CNT) and the other conductive particles with a solvent such as ethanol, propanol, butanol, toluene, N-mehyl-pyrrolidone, THF, acetone, cyclohexane, , Or the like, and then adding the binder while mixing them. In addition, the carbon nanotubes (CNTs) and the other conductive particles are preferably added together with a surfactant to improve their dispersibility.

The method for producing the semiconductive composition comprising the base resin and the conductive filler to form the semiconductive layer (2, 4) is not particularly limited. Preferably, the conductive filler is introduced into the surface of the base resin particles by using a device such as a Hybridizer (manufacturer: Nara Machinery), Nobilta (manufacturer: Hosokawa Micron) or Q-mix (Mitsui Mining) And in this case, the dispersibility of the conductive filler in the base resin can be further improved.

Here, the content of the conductive filler may be 0.5 to 20% by weight, preferably 2 to 10% by weight based on the total weight of the semiconductive composition. If the content of the conductive filler is less than 0.5% by weight, sufficient semiconducting properties can not be exhibited. If it exceeds 20% by weight, a high content of the conductive filler may increase the production cost, The surface smoothness of the semiconductive layer to be formed may be lowered.

The semiconductive composition comprises a crosslinking agent for crosslinking the base resin, a surfactant for improving the dispersibility of the conductive filler in the base resin, a lubricant for improving workability for forming a semiconductive layer, a cable And other additives such as antioxidants for prolonging life.

The type of the crosslinking agent is not particularly limited and may be appropriately selected according to the base resin used. Examples of the crosslinking agent include peroxides such as dicumyl peroxide (DCP) and di (t-butylperoxy) diisopropylbenzene have. Here, the content of the crosslinking agent may be 0.1 to 4 parts by weight, preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the base resin. When the crosslinking agent is added, crosslinked byproducts such as acetophenone and alpha methylstyrene may be generated to lower the electrical characteristics of the semiconductive layer (2, 4). However, the present invention is not limited to the above- By using only 0.1 to 4 parts by weight of the crosslinking agent, which is a small amount compared to 10 parts by weight of 100 parts by weight of the base resin, which is the amount of the crosslinking agent, it is possible to avoid or minimize the problem of generation of crosslinked byproducts and deterioration of electrical properties.

The kind of the surfactant is not particularly limited and examples thereof include sodium dodecyl sulfate (SDS), glycolic acid ethoxylate 4-nonylphenyl ether (GAENPE), n- A cationic surfactant such as dodecyltrimethylammonium bromide (DTAB), a nonionic surfactant such as Triton X-45, Triton X-114, and Triton X-100 , Or a combination thereof. The content of the surfactant may be 1 to 10 parts by weight, preferably 2 to 5 parts by weight based on 100 parts by weight of the conductive filler.

The kind of the lubricant is not particularly limited, and for example, fatty acid such as stearyl stearate, erucamide, stearic acid, or the like can be used. Here, the content of the lubricant is based on 100 parts by weight of the base resin 0.1 to 2 parts by weight.

The antioxidant is not particularly limited and includes, for example, amine-based antioxidants; Thioester-based antioxidants such as dialkyl esters, distearyl thiodipropionate, and dilauryl thiodipropionate; Tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenylene diphosphite, 2,2'-thiodiethylbis- [3- (3,5- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis- [3- Methyl-6-t-butylphenol), 2,2'-thiobis (6-t-butyl-4-methylphenol), triethylene glycol-bis- [3- (3- 4-hydroxy-5-methylphenyl) propionate]), and mixtures thereof, wherein the antioxidant is a mixture of 100 parts by weight of the base resin May be 0.1 to 2 parts by weight.

The semiconductive composition may have a different viscosity depending on the type and content of the base resin and the conductive filler contained therein, and the dispersibility of the conductive filler in the base resin. In the present invention, it is preferable that the semiconductive composition has an increased viscosity of 100 to 5,000 Pa · s, preferably 2,000 to 3,000 Pa · s, by the addition of the conductive filler. Here, the viscosity is a value measured at a fixing shear rate of ¹ x 10 ² s ^-1 at the melting temperature of the base resin. Also, the volume resistivity of the semiconductive composition may be ¹ x 10 ³ to 1 x 10 ¹¹ ? Cm.

Wherein the semiconductive composition has an increased viscosity of 100 to 5,000 Pa · s and a volume resistivity of 1 × 10 ³ to 1 × 10 ¹¹ Ω · cm by the addition of the conductive filler, Is a small amount so as not to lower the surface smoothness of the semiconductive layer formed from the semiconductive composition, and the conductive filler is uniformly dispersed in the base resin to form a conductive network, thereby exhibiting sufficient semiconducting properties.

On the other hand, the sheath layer 5 is preferably made of the same resin as the base resin of the semiconductive layer 4 for compatibility with the external semiconductive layer 4 and bonding strength.

The outer diameter, the thickness, etc. of the conductor 1, the inner semiconductive layer 2, the insulating layer 3, the outer semiconductive layer 4, the sheath layer 5, etc. constituting the power cable according to the present invention May be suitably selected by a person skilled in the art depending on the use of the cable, the operating voltage, and the like.

[Example]

Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

1. Manufacturing Example of Conductive Filler Containing Carbon Nanotubes (CNTs) Connected to each other through Bonding by Line Contact with Carbon Nano Plate (CNP)

Carbon nanotubes (CNP; manufactured by XG-Science, product name: xGNP) and carbon nanotubes (CNT, length: 30 μm, diameter: 20 nm, multiple wall) were dispersed in ethanol together with the surfactant Triton X-45 After homogenization and sonication in a sonication bath for 3 hours, these solutions were mixed and further sonicated for 1 hour. Next, aminosilane was added as a binder to the mixed solution and heated to 70 DEG C for 2 hours. Finally, ethanol was evaporated and dried in vacuum for 12 hours to obtain a conductive filler comprising CNTs connected to each other through bonding by line contact with CNP.

2. Production Example of Semiconductive Composition

Each of the semiconductive compositions according to Examples and Comparative Examples was prepared using the kneader to which the pelletizer was connected, with the components and contents shown in Table 1 below. The unit of the content shown in Table 1 below is parts by weight.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Base resin 100 100 100 100 100 CNP connected CNT 3 5 - - - CNT - - 5 - 3 CNP - - - 10 10 Antioxidant 0.5 0.5 0.5 0.5 0.5 Cross-linking agent 0.4 0.4 0.4 0.4 0.4

- Base resin: 50:50 blend resin of ethylene ethyl acrylate and ethylene butyl acrylate

- CNT: Multi-walled carbon nanotubes (length: 30 μm, diameter: 20 nm)

- CNP: Carbon nanoplate (size: 5 μm, thickness: <10 nm; manufacturer: XG-Science)

- Antioxidant: Tris (2,4-di-t-butylphenyl) phosphite

- Crosslinking agent: Dicumyl peroxide

3. Property evaluation

1) Evaluation of electrical characteristics (volume resistance)

A specimen having a width (W) of 1 cm, a length (L) of 5 cm and a thickness (T) of 1 mm was prepared from each of the semiconductive compositions according to Examples and Comparative Examples, and silver paste To measure the resistance (R) using a resistor at a cable use temperature of 90 deg. C, and the volume resistance (rho) was calculated using the following equation (1). When the volume resistivity exceeds 500? Cm, it is judged to exhibit insufficient anti-conduction characteristics.

2) Evaluation of surface smoothness

Specimens were prepared from each of the semiconductive compositions according to the Examples and Comparative Examples and their surfaces were observed under an optical microscope to determine the number of protrusions by size per unit area. If protrusions exceeding 100 탆 are not observed in a unit area of 60 cm ² , the surface smoothness of the semiconductive layer is judged to be good.

3) Evaluation of mechanical properties

The specimens were prepared from each of the semiconductive compositions according to Examples and Comparative Examples and tensile strength and tensile elongation were measured at room temperature and a tensile rate of 250 mm / min according to IEC 60811-1-1 standard, and a hot set ) Was evaluated by IECA T-562 after the specimens were exposed at 150 캜 for 15 minutes in an air condition.

The results of the physical property evaluation are shown in Table 2 below.

Properties unit Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Volume resistance Ω cm 400 96 800 2,000 1,200 The tensile strength Kgf / mm &lt; 2 &gt; 1.6 1.7 1.5 1.45 1.55 Tensile elongation % 410 390 400 190 320 Hot set % 75 70 70 85 80
Dendrite density 20 μm <size <50 μm / 1 cm 2 10 15 30 > 100 > 100 50 탆 < size < 100 탆 / 60㎠ 2 3 7 80 50 100 탆 < size < 150 탆 / 60㎠ 0 0 2 15 7 size> 150㎛ / 60㎠ 0 0 0 3 One

As shown in Table 2, Examples 1 and 2 according to the present invention are carbon nanotubes (CNTs) connected to each other via a bond by a line contact with conductive particles such as carbon nanoplate (CNP) The conductive filler exhibits a sufficient volume resistance of 400 or 90 Ω cm at the use temperature of the cable and the mechanical and thermal properties such as tensile strength, tensile elongation and hot set It was also confirmed that it was superior to Comparative Examples 1 to 3.

Further, the semiconductive composition according to Examples 1 and 2 does not produce protrusions having a size exceeding 100 탆 per unit area of 60 cm 2 of the sample sheet prepared therefrom, so that the surface smoothness of the semiconductive layer produced from the same . In this regard, FIG. 6 is an optical micrograph of a sample sheet made from the semiconductive composition according to Example 2, demonstrating the above results.

On the other hand, all of the semiconductive compositions according to Comparative Examples 1 to 3 were confirmed that their volume resistances exceeded 500 Ω cm so that sufficient semiconducting properties could not be realized, and mechanical and thermal properties such as tensile strength, tensile elongation, In addition, a large number of protrusions having a size exceeding 100 탆 per unit area of 60 cm 2 were found, and the surface smoothness of the semiconductive layer was also found to be poor. In this connection, FIG. 7 is an optical microscope photograph of a sample sheet made from a semiconductive composition according to Comparative Example 2, demonstrating the above results.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. . It is therefore to be understood that the modified embodiments are included in the technical scope of the present invention if they basically include elements of the claims of the present invention.

1: conductor 2: inner semiconductive layer
3: insulating layer 4: outer semiconductive layer
5: Sheath layer

Claims (18)

One or more conductors; An inner semiconductive layer surrounding the conductor; And an insulation layer surrounding the inner semiconductive layer,
The inner semiconductive layer is formed from a semiconductive composition comprising a base resin and a conductive filler including carbon nanotubes (CNTs) connected to each other via a bond by line contact with the conductive particles. And,
The bond due to the line contact is present on the surfaces of the conductive particles and the carbon nanotubes and is formed from a group consisting of a hydroxyl group (-OH), an amine group (-NH ₂ ), a carboxyl group (-COOH) and an epoxy group Silane coupling agents of at least one functional group selected from vinyltrimethoxysilane, methyltrimethoxysilane, aminopropyltrimethoxysilane, or derivatives thereof; Polyhydric alcohol binders of ethylene glycol, propylene glycol, glycerin, or derivatives thereof; And at least one binder selected from the group consisting of oxalic acid, propanedioic acid, butane diacid, and polycarboxylic acid coupling agents of derivatives thereof. The method according to claim 1,
Characterized in that the conductive particles have a flake or plate shape. 3. The method of claim 2,
The conductive particles may be at least one conductive particle selected from the group consisting of a metal flake, a metal plate, a carbon nano flake (CNF), and a carbon nano plate (CNP) Wherein the power cable is a cable. delete 4. The method according to any one of claims 1 to 3,
Wherein the base resin is ethylene ethyl acrylate (EEA), ethylene butyl acrylate (EBA), or a combination thereof. 4. The method according to any one of claims 1 to 3,
Wherein the base resin and the base resin constituting the insulating layer are the same base resin. The method according to claim 6,
Wherein the base resin is low density polyethylene (LDPE). 4. The method according to any one of claims 1 to 3,
Wherein the content of the conductive filler is 0.5 to 20 wt% based on the total weight of the semiconductive composition. 9. The method of claim 8,
Wherein the content of the electrically conductive filler is 2 to 10 wt% based on the total weight of the semiconductive composition. 4. The method according to any one of claims 1 to 3,
Wherein the weight ratio of the carbon nanotube (CNT) to the conductive filler is 80:20 to 70:30. The method according to claim 1,
Wherein the content of the binder is 1 to 20 parts by weight based on 100 parts by weight of the conductive filler. 4. The method according to any one of claims 1 to 3,
Characterized in that the conductive filler is introduced into the particle surface of the base resin. 4. The method according to any one of claims 1 to 3,
Wherein the semiconductive composition further comprises 0.1 to 4 parts by weight of a crosslinking agent based on 100 parts by weight of the base resin. 4. The method according to any one of claims 1 to 3,
Wherein the semiconductive composition further comprises 0.5 to 2 parts by weight of a lubricant, 0.5 to 2 parts by weight of an antioxidant, and 1 to 20 parts by weight of a surfactant based on 100 parts by weight of the base resin. 4. The method according to any one of claims 1 to 3,
Further comprising an outer semiconductive layer surrounding the insulating layer and a sheath layer surrounding the outer semiconductive layer. One or more conductors; An inner semiconductive layer surrounding the conductor; And an insulation layer surrounding the inner semiconductive layer,
The inner semiconductive layer is formed from a semiconductive composition comprising a base resin and a conductive filler including carbon nanotubes (CNTs) connected to each other via a bond by line contact with the conductive particles. And,
The bond due to the line contact is present on the surfaces of the conductive particles and the carbon nanotubes and is formed from a group consisting of a hydroxyl group (-OH), an amine group (-NH ₂ ), a carboxyl group (-COOH) and an epoxy group Silane coupling agents of at least one functional group selected from vinyltrimethoxysilane, methyltrimethoxysilane, aminopropyltrimethoxysilane, or derivatives thereof; Polyhydric alcohol binders of ethylene glycol, propylene glycol, glycerin, or derivatives thereof; And at least one binder selected from the group consisting of oxalic acid, propanedioic acid, butane diacid, and polycarboxylic acid bonding agents of derivatives thereof,
Wherein the semiconductive composition has a viscosity increased by the addition of the conductive filler of 100 to 5,000 Pa · s and a volume resistivity of 1 × 10 ³ to 1 × 10 ¹¹ Ω · cm and the viscosity of the base resin is determined by the melting temperature and the fixed shear rate Lt; ^{2 &gt;} s &lt; ^{-1 &} gt ;. 17. The method of claim 16,
Wherein the semiconductive composition has a viscosity increased by addition of the conductive filler of 2,000 to 3,000 Pa · s and a viscosity measured at a melting point of the base resin and a fixed shear rate of ¹ × 10 ² s ^-1 Power cable. delete

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