KR20140110139A

KR20140110139A - Power cable with low-temperature resistance and oil resistance

Info

Publication number: KR20140110139A
Application number: KR1020130022782A
Authority: KR
Inventors: 황현주; 손순일; 양훈철; 최아름
Original assignee: 엘에스전선 주식회사
Priority date: 2013-03-04
Filing date: 2013-03-04
Publication date: 2014-09-17
Also published as: KR102027003B1

Abstract

The present invention relates to a power cable with low-temperature resistance and oil resistance. Particularly, the present invention relates to a power cable including a sheath layer made of a sheath material with excellent basic physical properties, flame retardancy, and workability, etc., which not only prevents the generation of a harmful substance such as toxic gas in the combustion for disposal to be eco-friendly but also represents two properties of low-temperature resistance and oil resistance.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a power cable having low temperature resistance and oil resistance,

The present invention relates to a power cable having cold resistance and oil resistance. More particularly, the present invention relates to a method for producing a flame-retardant flame retardant which is not only environment-friendly, such as generating toxic substances such as toxic gases during burning for disposal, but also exhibits cold resistance and oil resistance which are difficult to secure simultaneously and is produced from a sheath material having intrinsic physical properties, To a power cable comprising a sheath layer.

When the sheath layer of a cable used in a low-temperature environment such as a vessel or polar bear that can receive the influence of low temperature seawater at any time does not have resistance to low temperature, i.e., cold resistance, the sheath layer is cracked Thereby causing damage to the product or failing to protect the insulating layer or the like inside the sheath layer.

Since the sheath layer and the insulating layer inside thereof are made of a polymer resin susceptible to oil, in order to effectively protect the sheath layer, the insulating layer, etc. made of such a polymer resin from external oil, the sheath layer is made of oil, mud ), That is, oil resistance and mud resistance.

The cold resistance of the sheath layer is related to the glass transition temperature (Tg) of the polymer resin constituting the sheath layer. As the glass transition temperature (Tg) is lower, the sheath layer exhibits excellent fluidity at low temperatures. In this connection, polyethylene has a disadvantage that it is weak in oil, mud and the like due to a material having a low glass transition temperature (Tg) of -60 캜 and excellent in low-temperature characteristics,

In order to satisfy both the cold resistance and the oil resistance of the sheath layer, a mixture of polyethylene and a resin having a polar group may be used. However, since both the cold resistance and the oil resistance depend on the side chain, i.e., the functional group, It is difficult to satisfy both the cold resistance at a cryogenic temperature and the oil resistance and muddy resistance resistant to oil, mud and the like which have a weak effect on the polymer.

On the other hand, chloroprene rubber and chlorosulfonated polyethylene, which are conventionally used as cable sheath layer materials having oil resistance in the prior art, are excellent in oil resistance characteristics of the resin itself due to the inclusion of a halogen element, And it was easy to satisfy the characteristics of the invention. However, it has become known that when the sheath layer produced using the resin is burned, toxic gases such as dioxin are released, which is detrimental to the human body as well as the environment. In this regard, development of new material materials with relatively low harmfulness is proceeding in addition to the aspect of regulation for environmental protection and the concern of development of environmentally friendly alternative materials.

In this connection, an ethylene-vinyl acetate copolymer resin having a vinyl acetate content of 70% for high oil resistance is used, a plasticizer for lowering the glass transition temperature (Tg) and a technique for additionally adding a silica-based reinforcement for improving mechanical strength (See Korean Patent Registration Nos. 10-0627512 and 10-0635585). However, the above-mentioned technology has a problem that the compound viscosity is lowered and the stickiness of the material itself is adhered to the compounding equipment of the metal material due to the stickiness of the material itself, which causes the process inability or the process capability to be deteriorated. Furthermore, there is a problem that it is difficult to reproduce / maintain the quality of the material itself due to lowering of the tensile strength at room temperature and lowering the dispersibility of the silica-based reinforcement added for mechanical property strengthening due to low shear stress due to the viscosity drop of the compound have.

Further, a technique using acrylonitrile butadiene rubber having a nitrile group for high oil resistance (see Japanese Patent Application Laid-Open Nos. 2007-028982 and 2007-077270) is disclosed, however, due to insufficient heat resistance and rubber properties There is a problem that there is a limit to the improvement of the modulus.

A technique for blending acrylonitrile butadiene rubber with a fluorine rubber (Japanese Patent Application Laid-Open No. 2003-268182) has been disclosed for compatibility with a plasticizer, but the compatibility of the fluorine rubber with the plasticizer has still been solved There is a problem that the desired level of cold tolerance can not be achieved.

In such a situation, a new sheath material excellent in environmental resistance, quality stability and process stability such as not causing toxic gas upon combustion, excellent in cold resistance, oil resistance, flexibility, flame retardancy and the like as a material itself and a sheath layer made therefrom A power cable is required.

An object of the present invention is to provide a power cable including a sheath layer made of an environmentally friendly sheath material, such as a toxic gas or the like, which is not generated during burning for disposal of a cable.

Another object of the present invention is to provide a power cable including a sheath layer made of a sheath material having both cold resistance and oil resistance at the same time, which is difficult to secure at the same time.

It is another object of the present invention to provide a power cable including a sheath layer made of a sheath material having quality stability and process stability due to intrinsic physical properties such as heat resistance, flame retardancy, and mechanical properties.

In order to solve the above problems,

Wherein the sheath layer comprises silicon rubber, 50 to 150 parts by weight of a reinforcing agent based on 100 parts by weight of the silicone rubber, and at least one reinforcing agent, And 1 to 7 parts by weight of a curing agent.

Wherein the silicone rubber comprises at least one silicon gum selected from the group consisting of methyl silicone, methylphenyl silicone, methylvinyl silicone, methylphenyl vinyl silicone and fluorine silicone as the main raw material .

Further, the silicone rubber has a molecular weight of 400,000 to 700,000 and a viscosity of 10 million cps or more.

Further, the silicone rubber has a tensile strength of at least 40 kgf / cm 2, an elongation of at least 120%, and a shore A hardness of at least 30 (measured according to standard ASTM D 2240).

The reinforcing agent is a dry or wet silica modified with at least one compound selected from the group consisting of amine, epoxy, thiol, carboxylic acid, sulfonic acid, phosphoric acid, phosphine and cyanic acid, and the curing agent is benzoyl peroxide, Alkyl peroxide, dicumyl peroxide, or a combination thereof.

Further, it is preferable that the silica is at least one selected from the group consisting of 3-aminopropyltrimethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, 3-glyoxylpropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, Aminopropyltrimethoxysilane, N- (beta-aminoethyl) gamma-aminopropylmethyldimethoxysilane, gamma-ureidopropyl (meth) acrylate, Trimethoxysilane, or a combination thereof. &Lt; Desc / Clms Page number 2 >

The curing agent is selected from the group consisting of 2,4-dichlorobenzoyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,5-dimethyl-2,5-di (tert- butylperoxy) -Butyl) peroxide, dicumyl peroxide, t-butylcumyl peroxide, or a combination thereof.

On the other hand, the silicone rubber composition further comprises a heat resistance improving agent, an anti-scorch agent, a flame retardant, a releasing agent, or a combination thereof.

Further, a power cable is provided, further comprising a bedding layer that entirely surrounds one or more conductors that the insulating layer surrounds, and a braided layer that audits the bedding layer.

Wherein the insulating layer and the bedding layer are fabricated from the silicone rubber composition.

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.

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 at least one conductor 1 made of a conductive material such as copper or aluminum, an insulating layer 2 made of an insulating polymer and surrounding each conductor 1, ), A bedding layer (3) which keeps the cross section of the cable in a circular shape and performs the functions of supplementing mechanical strength, water tightness and flame retardancy, and braiding which protects the inside of the cable from external impact or contamination Layer 4, a sheath layer 5 for cable protection, and the like.

The dimensions of the conductor 1, the insulating layer 2, the bedding layer 3, the braided layer 4 and the sheath layer 5 may vary depending on the use of the cable, the transmission voltage, ), The bedding layer (3), and the sheath layer (5) may be the same or different.

The insulating material forming the insulating layer 2 of the power cable according to the present invention is not particularly limited as long as it has an insulating property. In particular, most of the polymer resin plays an important role as an insulating material since it is an electrically insulating material. 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. For example, a polymer resin such as polyolefin such as polyvinyl chloride, polyethylene, polypropylene, ethylene / propylene / diene copolymer (EPDM), polyimide, polyamide imide, polyester, The same material as the material can be used as the insulating material for the insulating layer 2 of the cable.

The bedding layer 3 of the power cable according to the present invention is a three-phase cable comprising three conductors 1 arranged in a triangular shape as shown in Figures 1 and 2, The cross section is kept in a circular shape, and the function of supplementing the mechanical strength, water tightness, and flame retardancy of the cable is performed.

The material constituting the bedding layer 3 may vary depending on the use of the cable, the voltage of the cable, the use environment and the like. For example, a composite flame retardant material or a polyolefin resin based on polyvinyl chloride resin, especially ethylene- Halogen-flame retardant composite material based on an EVA copolymer resin, and may be made of the same material as the material of the sheath layer 5. The bedding layer 3 entirely encloses one or more conductors 1 wrapped in the insulating layer 2.

In addition, the power cable according to the present invention may have a structure in which the outer surface of the bedding layer 3 is surrounded by a braided layer 4 formed by braiding of copper or tin-plated copper wires. The braided layer 4 is formed to improve the tensile strength, load resistance, and flame barrier function. In the case of a non-halogen resin cable conforming to the International Electrotechnical Commission (IEC) standard, The cable to be installed has a built-in braid layer (4) or an external cable.

The power cable according to the present invention may include a sheath layer 5 made of a rubber composition containing a silicone rubber (hereinafter referred to as a 'silicone rubber composition') and surrounding the braided layer 4. The sheath layer 5 may be formed of a silicone rubber composition that is not a sheath material such as a crosslinking compound of conventional chlorosulfonated polyethylene (CSP) or non-halogen polyolefin (HF-PO). The insulating layer 2 and the bedding layer 3 may be made of the same material as the sheath layer 5.

The silicone rubber is a colorless or faint yellow elastic solid which has a slight fluidity even at room temperature and is also referred to as silicon rubber and has a molecular weight larger than that of silicone oil and has a molecular weight of several hundred thousand, preferably 400,000 to 700,000, a viscosity of 1,000 (Siloxane units from 5,000 to 10,000) higher than 10,000 cps. The silicon gum, which is the main raw material of the silicone rubber, may be methyl silicone, methylphenyl silicone in which a part of the methyl group is substituted with a phenyl group and / or vinyl group, methylvinyl silicone, methylphenylvinyl silicone, fluorine silicone and the like.

The silicone rubber composition may further comprise a reinforcing agent for mechanical strength. The content of the reinforcing agent may be 50 to 150 parts by weight based on 100 parts by weight of the silicone rubber. If the content of the reinforcing agent is less than 50 parts by weight, the mechanical strength and oil resistance of the silicone rubber composition may deteriorate and the specification may not be satisfied. When the content is more than 150 parts by weight, the elongation of the silicone rubber composition may deteriorate, So that cracks may occur in the sheath layer 5 at a low temperature.

In the power cable according to the present invention, the reinforcing agent is not particularly limited and may be, for example, dry or wet silica. Preferably, the silica may be dry silica having a low moisture content and a BET surface area of 150 to 400 M < 2 > / g.

The silica may preferably be surface treated with at least one member selected from the group consisting of amine, epoxy, thiol, carboxylic acid, sulfonic acid, phosphoric acid, phosphine and cyanic acid. Since normal silica has a hydroxyl group (-OH) on its surface, it has poor affinity with a relatively hydrophobic silicone rubber. The surface-treated silica has a functional group capable of chemical bonding to the surface, The non-covalent bonding can be performed, and the compatibility with the silicone rubber is improved.

The surface-treated or non-surface-treated silica may have an average particle diameter of 5 to 500 nm. When the average particle diameter is less than 5 nm, the surface energy and cohesive force of the silica particles are increased, so that functional groups capable of chemical bonding on the silica surface may not be uniformly formed. When the average particle diameter is more than 500 nm, uniform dispersion may be difficult.

The surface treated silica can be, for example, 3-aminopropyltrimethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, 3-glyoxylpropyltrimethoxysilane, 3- Aminopropyltrimethoxysilane, N- (beta-aminoethyl) gamma-aminopropylmethyldimethoxysilane, N- (beta-aminoethyl) Gamma-ureidopropyltrimethoxysilane, or a combination thereof.

The silicone rubber composition may further comprise a curing agent for crosslinking the silicone rubber. The content of the curing agent may be 1 to 7 parts by weight based on 100 parts by weight of the silicone rubber. If the content of the curing agent is less than 1 part by weight, the degree of crosslinking of the silicone rubber may be lowered, the mechanical properties of the silicone rubber composition at room temperature may not be maintained, and oil resistance and heat distortion characteristics may be deteriorated. Other addition reaction may be caused to lower the physical properties of the silicone rubber composition.

In the power cable according to the present invention, the curing agent is not particularly limited and includes, for example, organic peroxides such as benzoyl peroxide, alkyl-based peroxides and dicumyl peroxide, specifically 2,4-dichlorobenzoyl peroxide, (tert-butylperoxy) hexane, di (3-butylperoxy) peroxide, dicumylperoxide, t-butylcumylperoxide, 2,5- Or a combination thereof.

In addition to the reinforcing agent and the curing agent, the silicone rubber composition may further include a heat resistance improving agent, an anti-scorch agent, a flame retardant, a releasing agent, and the like. Particularly, the content of the flame retardant may be 50 to 100 parts by weight based on 100 parts by weight of the silicone rubber. If the content of the flame retardant is less than 50 parts by weight, the flame retardancy of the vertical ladder can not be satisfied. The elongation and flexibility of the silicone rubber composition may be deteriorated.

The silicone rubber may have a molecular weight of hundreds of thousands, preferably 400,000 to 700,000. If the molecular weight of the silicone rubber is less than 400,000, the mechanical properties and oil resistance before and after heating may be lowered. In addition, the silicone rubber may exhibit a tensile strength of at least 40 kgf / cm 2, preferably 70 to 90 kgf / cm 2. When the tensile strength of the silicone rubber is less than 40 kgf / cm 2, it is inadequate to meet the cable sheath standard and it is inevitable to add an excessive amount of a reinforcing agent to the silicone rubber composition, so that the flexibility and cold resistance of the silicone rubber composition may be deteriorated.

The elongation percentage of the silicone rubber may be 120% or more, preferably 300 to 500%. When the elongation percentage of the silicone rubber is less than 120%, the sheath layer formed from the silicone rubber composition is unsuitable for the cable sheath standard, and the melt strength is lowered, so that molding during the extrusion of the silicone rubber composition may be difficult. The hardness of the silicone rubber may be 30 or more, preferably 50 to 80, based on the shore A hardness (ASTM D 2240), and when the Shore A hardness of the silicone rubber is less than 30, Damage to the silicone rubber composition due to external impact or scratching may occur before and after the extrusion, and the mechanical strength of the silicone rubber composition may be lowered.

[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

In order to evaluate the physical properties of the sheath layer 5 included in the power cable according to the present invention, the rubber compositions of Examples and Comparative Examples were prepared by the constituents and contents shown in Table 1 below. Here, the unit of the content is parts by weight.

division Example Comparative Example One 2 3 One 2 3 4 Silicone rubber a 100 Silicone rubber b 100 Silicone rubber c 100 Silicone rubber d 100 Silicone rubber e 100 Silicone rubber f 100 Nonhalogen
Polyolefin 100 Reinforcing agent 100 100 100 100 40 40 100 Hardener 5 4 6 5 5 4 5 Flame retardant 100 80 80 100 100 40 150

- Silicone rubber a: methyl silicone, molecular weight: 430,000, viscosity: 35 million cps, tensile strength: 50 kgf / cm2, hardness: 60

- silicone rubber b: methyl silicone, molecular weight 500,000, viscosity 42 million cps, tensile strength 55 kgf / cm 2, hardness 42

- silicone rubber c: methyl silicone, molecular weight 600,000, viscosity 60,000 cps, tensile strength 60 kgf / cm 2, hardness 51

- silicone rubber d: methyl silicone, molecular weight 300,000, viscosity 25 million cps, tensile strength 32 kgf / cm 2, hardness 32

- silicone rubber e: methyl silicone, molecular weight: 350,000, viscosity: 8 million cps, tensile strength: 30 kgf / cm2, hardness: 24

- silicone rubber f: methyl silicone, molecular weight 700,000, viscosity 9.2 million cps, tensile strength 42 kgf / cm 2, hardness 26

- non-halogen polyolefin: ethylene vinyl acetate (manufacturer: Fountec, product name: MX-2220B; vinyl acetate content: 70%)

- Reinforcement: Silica (manufacturer: Rhodia, product name: zeosil 155PD)

- Hardener: peroxide (manufacturer: PERGAN, product name: Peroxan PK 295P)

- Flame retardant: aluminum hydroxide (manufacturer: KC Chemical, product name: KH-101LP)

An insulating layer 2 made of an ethylene / propylene / diene copolymer (EPDM) (manufacturer: Fountec, product name: RZ-P0098) and a non-halogen polyolefin ethylene (ethylene terephthalate) A bedding layer 3 consisting of a vinyl acetate resin (vinyl acetate content 70%) (manufacturer: Fountec, product name: MX-2220B) was formed and then a continuous vulcanizing equipment By setting the sheath layer 5 from the rubber composition of each of Examples 1 to 3 and Comparative Examples 1 to 4 prepared at a crosslinking temperature of 220 to 240 DEG C using a shear layer (set at a temperature of 30 DEG C or less) : 3 x 24 SQ).

2. Measurement and evaluation of physical properties of cable specimens

end. Mechanical properties evaluation at room temperature and after heating

IEC 60811-1-1, -2 measured at a speed of 250 mm / min. The reference value is in accordance with IEC 60092-359.

I. Evaluation of oil resistance and resistance to mud

For oil or mud specified in NEK 606/2004, the tensile residual rate, percent elongation, volume change and mass change after impregnation were measured at a specified temperature and time. Here, the tensile residual rate and the elongation percentage were evaluated in accordance with IEC 60811-2-1, and the volume change and the mass change were evaluated in accordance with ASTM 471.

All. Cold resistance evaluation

CSA 22.2 No. 38 cable specimens with a length of 130 mm were allowed to stand at the experimental temperatures of -40 ° C, -50 ° C and -60 ° C for 4 hours, and a weight of 1.35 kg was dropped at a height of 915 mm, Cracks should not occur on the above specimens.

la. Flammability evaluation

IEC 60332-3-22 cat. A, the flame should be applied to the cable of length 3.5 m for 40 minutes and the burning length should not exceed 2.5 m.

hemp. Evaluation of heat deformability

Measure the change in thickness after applying a load at 80 ° C for 6 hours using a standard blade to a cable of 100 mm length according to IEC 60811-3-1.

bar. 10% modulus

To compare the flexibility according to the material of the sheath layer (5), the modulus of 10% in the stress-strain curve is compared and the smaller the value, the more flexible it is.

The mechanical properties, oil / mud resistance, cold resistance, heat distortion and 10% modulus of the cable specimen measured / evaluated according to the above evaluation method are shown in Table 2 below.

Reference value Example Comparative Example One 2 3 One 2 3 4 Room temperature The tensile strength
(kgf / mm2) 0.92 0.987 1.02 0.95 0.77 0.86 0.88 0.94 Elongation (%) 120 288.18 350.1 400 180 301 140 170 After heating Tensile Residue (%) 70 98 112 89 62 73.9 68.22 98.55 Renal survival rate (%) 70 110 87 85 60.1 75 110.1 101.2 Oil resistance
(IRM902,
100 DEG C, 168 hours) Tensile Residue (%) 70 104.66 98.76 99.87 73.31 102.44 71.12 74.33 Renal survival rate (%) 70 101.32 100.09 79.98 75.4 98.12 73.42 76.7 Oil resistance
(IRM903,
100 DEG C, 168 hours) Tensile Residue (%) 70 93.11 94.56 89.99 67.14 91.09 75.4 94.23 Renal survival rate (%) 70 89.79 90.57 83.49 62.74 87.77 71.28 83.53 Volume change (%) ± 30 16.2 15.44 25.22 35.6 18.4 28.22 28.05 Mass change (%) ± 30 11.7 12.34 20.8 34.9 13.9 26.39 22.94 My Mud Castle
(oil based mud,
70 ° C, 56 days) Tensile Residue (%) 75 80.95 82.1 79.99 59.5 93 73.44 93.29 Renal survival rate (%) 75 78.94 76.42 78.82 55.4 92.7 75.12 84.4 Volume change (%) ± 20 17.4 15.5 18.66 39.8 28.12 25.44 16.62 Mass change (%) ± 15 15 13.66 18.77 37.4 20 25.7 12.82
Cold resistance -40 ° C pass pass pass pass pass pass pass -50 ℃ pass pass pass pass pass pass fail -60 ° C pass pass pass pass pass pass fail Flame Retardant ≤ 250 103 78 60 98 110 100 200 Heat distortion 80 ° C, 4 hours ≤50% 21 30 16.7 40.5 38.1 54.3 28.5 10%
Modulus kgf / cm2 8.64 9.01 8.01 6.4 7.12 8.11 10.98

As shown in Table 2, the cable specimen according to Comparative Example 1 had a molecular weight of 300,000 and a tensile strength of 32 kgf / cm < 2 > because the silicone rubber constituting the sheath layer 5 thereof had a low molecular weight of 30,000, , Mechanical properties such as tensile residual rate and elongation percentage after heating, resistance to oil IRM903 and mud were found to be less than the reference value.

In the cable specimen according to the comparative example 2, the silicone rubber constituting the sheath layer 5 had a molecular weight of 350,000, a tensile strength of 30 kgf / cm 2, a Shore A hardness of 24, and a reinforcing agent content of 40 parts by weight, The mechanical properties such as tensile strength at room temperature were poor and the mechanical properties after heating were also inferior to those of Examples 1 to 3.

In the cable specimen according to the comparative example 3, the Shore A hardness of the silicone rubber constituting the sheath layer 5 was 26, and the reinforcing agent and the flame retardant content were each 40 parts by weight. Thus, the tensile strength at room temperature, , And it was confirmed that the oil resistance to oil IRM903 was inferior to those of Examples 1 to 3. Further, it was confirmed that the heating deformation of the specimen exceeded the reference value and was poor.

Further, in the cable specimen according to Comparative Example 4, a non-halogen polyolefin was used as a resin constituting the sheath layer 5, which was poor in cold resistance at -50 캜 and -60 캜, and oil resistance to oil IRM 902 was excellent in Example 1 To < RTI ID = 0.0 > 3, < / RTI >

On the other hand, the cable specimens according to Examples 1 to 3 themselves include the sheath layer 5 made of silicone rubber which is excellent in oil resistance, flexibility and cold resistance and has excellent inherent physical properties, Oil resistance, mud resistance, cold resistance, flame retardancy, and heat resistance all met the standard values.

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: insulating layer
3: bedding layer 4: braided layer
5: Sheath layer

Claims

A power cable comprising at least one conductor, an insulating layer surrounding each conductor, and an outermost sheath layer,
Wherein the sheath layer is made from a silicone rubber composition comprising silicone rubber, 50 to 150 parts by weight of a reinforcing agent, and 1 to 7 parts by weight of a curing agent based on 100 parts by weight of the silicone rubber.

The method according to claim 1,
Wherein the silicone rubber comprises one or more silicon gums selected from the group consisting of methyl silicone, methylphenyl silicone, methylvinyl silicone, methylphenylvinyl silicone and fluorosilicone as main raw materials.

3. The method of claim 2,
Wherein the silicone rubber has a molecular weight of 400,000 to 700,000 and a viscosity of 10 million cps or more.

The method of claim 3,
Characterized in that the silicone rubber has a tensile strength of at least 40 kgf / cm 2, an elongation of at least 120%, and a shore A hardness of at least 30 (measured according to specification ASTM D 2240).

5. The method according to any one of claims 1 to 4,
Wherein the reinforcing agent is a dry or wet silica modified with at least one compound selected from the group consisting of amine, epoxy, thiol, carboxylic acid, sulfonic acid, phosphoric acid, phosphine and cyanic acid, and the curing agent is selected from the group consisting of benzoyl peroxide, Peroxide, dicumyl peroxide, or a combination thereof.

6. The method of claim 5,
Wherein the silica is selected from the group consisting of 3-aminopropyltrimethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, 3-glyoxylpropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3- Aminopropyltrimethoxysilane, isocyanatopropyltrimethoxysilane, N- (beta-aminoethyl) gamma-aminopropyltrimethoxysilane, N- (beta-aminoethyl) gamma-aminopropylmethyldimethoxysilane, gamma- &Lt; / RTI > or a combination thereof.

6. The method of claim 5,
Wherein the curing agent is selected from the group consisting of 2,4-dichlorobenzoyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,5-dimethyl-2,5-di (tert- butylperoxy) ) Peroxide, dicumyl peroxide, t-butylcumyl peroxide, or a combination thereof.

5. The method according to any one of claims 1 to 4,
Wherein the silicone rubber composition further comprises a heat resistance improving agent, an anti-scorch agent, a flame retardant agent, a releasing agent, or a combination thereof.

5. The method according to any one of claims 1 to 4,
Wherein the power cable further comprises a bedding layer which entirely surrounds one or more conductors wrapped by the insulating layer, and a braided layer to audit the bedding layer.

10. The method of claim 9,
Wherein the insulating layer and the bedding layer are made from the silicone rubber composition.