KR101931439B1 - Composition for electric wire fireproof cover, method for manufacturing electric wire fireproof cover using the composition, and electric wire including the same composition - Google Patents

Abstract

The present invention provides a composition for a fireproof electric wire cover and a method for manufacturing a fireproof electric wire cover and electric wire using the same. The composition contains: silicone rubber paste having solid silicone rubber which includes first silicone rubber and second silicone rubber with degree of flexibility higher than that of the first silicone rubber, a plasticizer, and expanded graphite; and a curing agent. The curing agent includes: a first curing agent having bis (2,4-dichlorobenzoyl) peroxide and silicone oil; and a second curing agent having silica, tetramethyl tetravinyl cyclotetrasiloxane, octamethylcyclotetrasiloxane, a curing retarder, and a platinum catalyst. Therefore, fire resistance and tear strength are enhanced and the composition can be easily manufactured into a desired shaped fireproof electric wire cover.

Description

TECHNICAL FIELD The present invention relates to a composition for a wire refractory cover, a method for manufacturing a wire refractory cover using the same,

More particularly, the present invention relates to a composition for a wire refractory cover, a method for manufacturing a wire refractory cover using the same, and a wire. More particularly, the present invention relates to a composition for wire refractory cover, which comprises an expansive flame retardant material to improve the flame retardancy, The present invention relates to a composition for a wire refractory cover, a method for manufacturing a wire refractory cover using the same, and a wire.

The electric wire serves to supply electric power to various electronic devices or to transmit communication signals between electronic devices. These wires are provided with conductive wires or optical cables made of copper or the like so as to transmit a current or a signal to the inside, and a covering material is disposed on the outside of the wires so as to protect the conductive wires or optical cables.

At this time, the cover material disposed outside the wire uses PVC (polyvinyl chloride) or PE (polyethylene) which is excellent in insulation to prevent a short circuit between the conductive line or optical cable for transmitting electric power or signal.

However, since the PVC and PE are vulnerable to heat, they may be exposed to the outside due to the flame being lost due to the flame. Therefore, in order to reduce the damage to people and property, It needs to be maintained.

Accordingly, a fireproof cover is disposed outside the electric wire to prevent the electric wire from being disconnected for a period of time for taking various measures to reduce damage to property and property when a fire occurs.

On the other hand, the refractory cover mainly uses silicone rubber having high heat resistance. However, the conventional refractory cover has a problem that the tear strength is so low that it tears easily even to a small external use.

Further, in the case of the liquid silicone rubber used as the main material of the refractory cover, since the viscosity is low, hardening is difficult and injection is difficult, and since it is required to be manufactured in a desired shape using a mold frame, , Manufacturing process and cost increase.

Korean Patent Publication No. 10-2008-0079515

It is an object of the present invention to provide a composition for a wire refractory cover which can be easily injection-molded and can improve tear strength, a method for manufacturing a wire refractory cover using the same, and a wire.

An aspect of the present invention is a silicone rubber dough comprising a first silicone rubber and a solid silicone rubber comprising a second silicone rubber having a higher softness than the first silicone rubber, a plasticizer and expanded graphite; And curing agents; Wherein the curing agent comprises a first curing agent comprising bis (2,4-dichlorobenzoyl) peroxide and a silicone oil; And a second curing agent including silica (Silica), tetramethyl tetravinyl cyclotetrasiloxane, octamethylcyclotetrasiloxane, a curing retardant, and a platinum catalyst; The present invention provides a composition for a wire refractory cover.

According to a preferred aspect of the present invention, 0.02 to 0.04 parts by weight of the plasticizer and 90 to 110 parts by weight of the expanded graphite may be included relative to 100 parts by weight of the silicone rubber.

According to a preferred feature of the present invention, the curing agent may be included in an amount of 15 to 25 parts by weight based on 100 parts by weight of the silicone rubber.

According to a preferred aspect of the present invention, the weight ratio of the first curing agent to the second curing agent may be 0.9: 1 to 1: 0.9.

According to a preferred aspect of the present invention, the weight ratio of the first silicone rubber and the second silicone rubber may be 0.9: 1 to 1: 0.9.

According to another aspect of the present invention, there is provided a wireless communication system including at least one linear core capable of transmitting power or signals; An insulating sheath surrounding the core; And a wire refractory cover surrounding the insulation sheath, the wire refractory cover including the wire refractory cover composition; As shown in Fig.

According to a preferred feature of the present invention, the electric wire may further include a mesh tube disposed between the insulation coating and the wire fireproof cover.

Yet another aspect of the present invention provides a method of manufacturing a semiconductor device, comprising: preparing a solid silicone rubber including a first silicone rubber and a second silicone rubber having a higher softness than the first silicone rubber; Mixing the solid silicone rubber with a plasticizer and expanded graphite to form a silicone rubber dough; Mixing the silicone rubber dough with a curing agent to form a sheet form; And injecting the silicone rubber dough mixed with the hardener into a wire refractory cover using an injection machine; Wherein the curing agent comprises a first curing agent comprising bis (2,4-dichlorobenzoyl) peroxide and a silicone oil; And a second curing agent including silica (Silica), tetramethyl tetravinyl cyclotetrasiloxane, octamethylcyclotetrasiloxane, a curing retardant, and a platinum catalyst; The present invention provides a method of manufacturing a wire refractory cover.

According to a preferred aspect of the present invention, the step of injecting the wire refractory cover further comprises: a primary vulcanizing step performed at 600 to 700 ° C; A secondary vulcanizing step carried out at 210 to 290 占 폚 and carried out in a horizontal rail having a length of 7 to 8 m; And a tertiary vulcanization step performed at 180 to 220 캜 and performed in an oven for 3.5 to 4.5 hours; . ≪ / RTI >

The composition for wire refractory cover according to an embodiment of the present invention can improve the fire resistance of the wire refractory cover including expanded graphite and at the same time the expanded graphite can act as a filler to prevent crack propagation and improve the tear strength .

In addition, since the composition for a wire refractory cover contains as a main component a solid silicone rubber including a first silicone rubber having excellent heat resistance and a second silicone rubber having a higher concentration (Consistency) than the first silicone rubber, It is possible to improve the moldability and at the same time reduce the manufacturing cost and time.

In addition, since the composition for wire refractory cover contains expansive unfoamed expanded graphite but contains a certain amount of a second curing agent containing platinum as a curing agent, it is possible to prevent the decrease in curing due to expanded graphite that occurs during the manufacturing process .

1 is a cross-sectional view schematically showing a structure of a wire according to an embodiment of the present invention

The embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the following embodiments. Further, the embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

In addition, the present invention is described with respect to a composition for a wire refractory cover, but the composition can be applied not only to a wire refractory cover but also to a technology used for signal transmission such as an optical cable.

A composition for a wire refractory cover according to an embodiment of the present invention includes a first silicone rubber and a solid silicone rubber including a second silicone rubber having a higher concentration than the first silicone rubber than the first silicone rubber; A silicone rubber paste including a plasticizer and expanded graphite; And a curing agent.

The curing agent may include a first curing agent including bis (2,4-dichlorobenzoyl) peroxide and a silicone oil; And a second curing agent including silica (Silica), tetramethyl tetravinyl cyclotetrasiloxane, octamethylcyclotetrasiloxane, a curing retardant, and a platinum catalyst; .

The composition for the wire refractory cover may include 0.02 to 0.04 parts by weight of the plasticizer and 90 to 110 parts by weight of the expanded graphite relative to 100 parts by weight of the silicone rubber.

The curing agent may be included in an amount of 15 to 25 parts by weight based on 100 parts by weight of the silicone rubber.

The weight ratio of the first curing agent to the second curing agent may be 0.9: 1 to 1: 0.9, and the weight ratio of the first silicone rubber and the second silicone rubber may be 0.9: 1 to 1: 0.9.

In the present invention, it is possible to produce a wire refractory cover using such a wire refractory cover composition. Hereinafter, a method for manufacturing a wire refractory cover according to an embodiment of the present invention will be described in detail.

A solid silicone rubber including a first silicone rubber as a first component and a second silicone rubber having a higher softness than the first silicone rubber is first prepared.

The solid silicone rubber may be formed by mixing at least two kinds of silicone rubbers. In this embodiment, the first and second silicon rubbers are mixed to form the silicone rubber.

The first silicone rubber may be a commercially available silicone rubber having excellent fire resistance and flame retardancy. Further, the first silicone rubber can use a silicone rubber having strong heat resistance, good thermal stability, and high insulation characteristics.

The properties of the materials required to be used for this first silicone rubber are those having a specific gravity of 1.08 to 1.10, a durometer measurement of 32 to 37 Durometer Shore A, a tensile strength of 8 to 11 MPa, an elongation at fracture of 740 To 910%, a tear strength of 24.0 to 31.0 kN / m, and a compression set ratio (22 hours, 177 ° C) of 31 to 41%.

The first silicone rubber may serve as a base component in the composition for a wire refractory cover according to an embodiment of the present invention.

The second silicone rubber can use a silicone rubber having a higher softness than the first silicone rubber. The term "softness" refers to the state of hardness of an object in the middle of a conductor and liquid, which means the degree of fluidity of the silicone rubber.

The properties of the material required to be used for such second silicone rubber may be plasticity of 240 or more. The material that can be used for the second silicone rubber is a silicone rubber having a density of 1.1 to 1.2 g / cm 3, a hardness (JIS type A) of 48 to 50, a tensile strength of 9.1 to 9.5 MPa, an elongation ) Is 510 to 550%, and the tear strength is 20 to 25 N / mm.

In the case of the liquid silicone rubber which has been used as the main material of the conventional refractory cover, since the viscosity is low, the injection molding can not be performed and the mold is required to be manufactured in a desired shape. Therefore, the shape of the refractory cover is restricted, There is a drawback that it is expensive.

However, the composition for a wire refractory cover according to this embodiment uses a first silicone rubber satisfying the above-mentioned characteristics as a base material and a silicone rubber having a higher softness than the first silicone rubber as the second silicone rubber. A solid silicone rubber to be formed is used.

Therefore, the wire refractory cover can be easily formed by the injection apparatus, which makes it possible to reduce the manufacturing process and cost, and to more easily form the wire refractory cover of the desired shape.

In this case, the weight ratio of the first silicone rubber and the second silicone rubber may be 0.9: 1 to 1: 0.9 in order to maintain the fire resistance characteristic and the workability of the wire refractory cover composition at a desired level. If the weight ratio of the first silicone rubber and the second silicone rubber is out of the range of 0.9: 1 to 1: 0.9, there may arise a problem that the refractory characteristics are reduced or the workability of the wire refractory cover composition is reduced. For example, when the weight ratio of the first silicone rubber and the second silicone rubber is out of the range of 0.9: 1 to 1:09, the heat resistance and the differential properties are reduced. Thus, the fire resistance test C of the Ministry of Land, -2) condition can not be satisfied.

Next, the plasticizer as the second component and the expanded graphite as the third component are mixed with the solid silicone rubber to form a silicone rubber paste.

The plasticizer improves the processability of the solid silicone rubber and imparts flexibility to the product in the process of producing the composition for electric wire refractory cover.

Such a plasticizer may include polydimethylsiloxane or octamethyltetrasiloxane, and may preferably include octamethyltetrasiloxane. The plasticizer may include polydimethylsiloxane or octamethyltetrasiloxane.

The plasticizer as the second component may be included in an amount of 0.02 to 0.04 part by weight based on 100 parts by weight of the silicone rubber as the first component. If the content of the plasticizer is less than 0.02 parts by weight or more than 0.04 parts by weight, the workability of the solid silicone rubber is considerably deteriorated or becomes too thin, so that it is difficult to prepare the silicone rubber dough into a sheet form suitable for injection molding .

On the other hand, if a wire refractory cover is manufactured using a solid silicone rubber, the tear strength of the second silicone rubber may be relatively low. This may cause a problem that the manufactured wire refractory cover is easily torn by an external impact, and the torn portion is further damaged by a small force.

However, the composition for wire refractory cover according to one embodiment of the present invention can increase the tear strength of the wire refractory cover produced by the expansion graphite serving as a filler of solid silicone rubber.

The expanded graphite may be obtained through oxidation of natural or synthetic graphite, and the oxidizing agent used for the oxidation of graphite may be sulfuric acid or nitric acid. When the expanded graphite is heated at room temperature to about 800 ° C for a short period of time as in the case of a fire, the non-volatile change (based on the c-axis direction of the crystal) of the expanded graphite may be 100 ml / g or more.

In addition, the average particle size D ₅₀ of the expanded graphite may be several tens to several thousands of micrometers. If the average particle size of the expanded graphite is too small, the flame retarding effect is remarkably reduced. If the average particle size of the expanded graphite is too large, the physical properties of the manufactured electric wire fireproof cover may be reduced. In the present embodiment, the preferred density of expanded graphite may be 0.4 to 2 g / cm < 3 >, but the present invention is not limited thereto.

Such expanded graphite has a characteristic of being formed of a porous layer by burning when exposed to heat at high temperatures such as a fire accident, and the carbonized layer is formed of porous graphite, which is a non-combustible material. That is, the composition for wire refractory cover according to one embodiment of the present invention can greatly improve the fire resistance or flame retardancy of the wire refractory cover produced from expanded graphite.

In the present embodiment, when 100 parts by weight of the silicone rubber is contained, 90 to 110 parts by weight of expanded graphite may be included. When the expanded graphite is less than 90 parts by weight, the produced wire refractory cover may have insufficient fire resistance or flame retardancy. If the expanded graphite exceeds 110 parts by weight, the workability of the composition for wire refractory cover decreases and the ductility of the manufactured wire refractory cover decreases May cause problems.

Therefore, in order to secure the workability of the wire refractory cover composition and to secure the ductility of the wire refractory cover, the wire refractory cover composition according to one embodiment of the present invention, when 100 parts by weight of the silicone rubber is contained, It is preferable that 90 to 110 parts by weight of graphite is included.

Then, the silicone rubber, the plasticizer and the expanded graphite described above are mixed and kneaded in a kneader to form a silicone rubber dough.

Next, a step of mixing a curing agent in the silicone rubber dough in an open roller and forming it into a sheet form is carried out. The curing agent is added to perform the curing process of the silicone rubber dough.

Silicone rubber generally performs curing by crosslinking a siloxane chain by addition reaction of a polysiloxane containing a vinyl group and a polysiloxane having Si-H bonds. At this time, the silicone rubber dough formed by mixing the first to third components is not cured properly with the curing agent generally used because of the expanded graphite contained therein.

That is, there is a problem that silicon hydride (Si-H) is hardly attached to an unsaturated carbon-carbon bond by a commonly used curing agent. Therefore, there is a need for a method for improving the curability of a composition for wire refractory cover, including expanded graphite.

The composition for a wire refractory cover according to an embodiment of the present invention may contain not only a first curing agent including bis (2,4-dichlorobenzoyl) peroxide and silicone oil but also silica, tetramethyl tetravinyl cyclotetrasiloxane, octamethylcyclotetrasiloxane , A curing retarder and a second curing agent comprising platinum as a catalyst.

At this time, since the second curing agent includes a platinum catalyst, the silicone hydride (Si-H) of the silicone rubber paste is adhered to the unsaturated carbon-carbon bond during the curing reaction to eliminate the shortage of curing by the expanded graphite, Can be improved. In addition, platinum may serve to increase tensile force and cohesion force of a product manufactured using the composition for wire refractory cover according to an embodiment of the present invention.

Further, in order to further secure the curability, the weight ratio of the first curing agent and the second curing agent may be adjusted to 0.9: 1 to 1: 0.9 in the wire fireproof cover composition according to one embodiment of the present invention. In this case, when the silicone rubber is contained in an amount of 100 parts by weight, the content of the curing agent may be 15 to 25 parts by weight. If the content of the curing agent is less than 15 parts by weight, the curability may be decreased. If the content of the curing agent is more than 25 parts by weight, the fire resistance may decrease.

Next, the completed sheet is injected into an injection machine to perform a step of injecting a wire refractory cover of a desired standard.

The wire refractory cover injection step is carried out at a first curing step performed at 600 to 700 ° C, a second curing step performed at 210 to 290 ° C, a second curing step performed at a horizontal rail having a length of 7 to 8 m, And a tertiary vulcanization step carried out in the oven for 3.5 to 4.5 hours. In this case, if the primary and secondary vulcanizing conditions do not satisfy the above conditions, the composition for a wire refractory cover to be manufactured is not completely cured and the stability of the product is lowered, and thus an uncured product can be produced.

The finished wire fireproof cover can be cut to a certain size, and a mesh tube can be inserted inside to complete the product. The mesh tube may be a cylindrical mesh formed of nylon fibers.

1 is a cross-sectional view schematically showing a structure of a wire according to an embodiment of the present invention.

Referring to Fig. 1, the electric wire 10 according to the present embodiment includes at least one core 11 and an insulating sheath 12. The core (11) is linear and serves to transmit electric power or signals, and the insulation coating (12) covers the core (11) and protects it. At this time, the insulation coating 12 may be made of polyvinyl chloride (PVC) or polyethylene (PE) having excellent insulation properties.

A wire refractory cover 30 is formed so as to surround the insulating cover 12 on the outer side of the insulating cover 12. The wire refractory cover 30 includes the above-mentioned composition for a wire refractory cover of the present invention. Therefore, the electric wire 10 of this embodiment can be improved in fire resistance and tear strength.

On the other hand, the mesh tube 20 may be further disposed between the insulation coating 12 and the wire fireproof cover 30. The mesh tube 30 is formed by using a cylindrical mesh formed of nylon fibers and serves to prevent the sharp material from damaging the insulation cover 12 and the core 11. [

Hereinafter, examples and comparative examples are prepared in order to examine the excellent characteristics and effects of the composition for wire refractory cover according to the present invention.

[Example 1]

25 kg of the product name RBB-2400-30 Base, product name of XIAMETER Co., Ltd., is prepared from the first silicone rubber and 25 kg of the product name SH 52 U from DOW CORNING is provided with the second silicone rubber.

The product name RBB-2400-30 Base, manufactured by XIAMETER, which is used as the first silicone rubber, has a specific gravity of 1.08 to 1.10, a durometer measurement value of 32 to 37 Durometer Shore A, a tensile strength of 8 to 11 MPa, 740 to 910%, a tear strength of 24.0 to 31.0 kN / m, and a compression set ratio (22 hours, 177 ° C) of 31 to 41%.

The product SH 52 U of DOW CORNING used as the second silicone rubber has a plasticity of 240 or more, a density of 1.1 to 1.2 g / cm 3, a hardness (JIS type A) of 48 to 50, a tensile strength Of 9.1 to 9.5 MPa, an elongation (JIS # 3) of 510 to 550% and a tear strength of 20 to 25 N / mm.

Next, 750 g of PMX-0930 SILANOL FLUID manufactured by XIAMETER Co., Ltd. was mixed with a solid silicone rubber containing the first and second silicone rubbers as a plasticizer, and further 50 kg of expanded graphite (expanded graphite) Knead in Kneader to prepare silicone rubber dough.

Next, 10 kg of the curing agent is mixed in the silicone rubber dough in an open roller to prepare a sheet form. The curing agent was prepared by using PERKADOX PD-50S-PS containing bis (2,4-dichlorobenzoyl) peroxide and silicone oil of Akzo Noble Polymer Chemical as a first curing agent and containing a platinum catalyst as a second curing agent RD-27 from DOW CORNING is used.

Next, a silicon rubber dough produced in a sheet form is injected from an injection machine to produce a wire refractory cover.

Table 1 below shows the tensile strength, elongation and tear strength of Samples 1 to 4 prepared through the examples of the present invention, respectively. Referring to Table 1, it can be seen that the present embodiment satisfies all the results of measuring the fire resistance characteristics for 120 minutes under the fire resistance test (C-2) test of the Ministry of Land, Transport and Maritime Affairs Notice No. 2014-200.

Sample Tensile Strength [kgf / cm ² ] Elongation [%] Tear strength [kgf / cm] One 21.2 350.3 9.21 2 20.2 354.9 9.13 3 19.4 358.1 9.33 4 19.8 333.8 9.80

[Comparative Example 1]

The wire refractory cover of Comparative Example 1 uses a liquid silicone rubber instead of the solid silicone rubber, and the other conditions are the same as those of the embodiment.

In the case of Comparative Example 1, since the liquid silicone rubber is used, the silicone rubber paste can not be produced in the form of a sheet, so that it is difficult to use an injection machine. Further, even if the silicone rubber dough is produced in the form of a sheet, there is a problem that the silicone rubber dough does not have a proper thickness to maintain the fire resistance after injection or holes are generated.

[Comparative Example 2]

The wire refractory cover of Comparative Example 2 does not contain expanded graphite, and other conditions are the same as those of the embodiment. Comparative Example 2, which does not contain expanded graphite, has a problem of not only reducing the fire resistance but also significantly lowering the tear strength as compared with the examples. That is, in the case of the wire refractory cover according to the present invention, expanded graphite has excellent fire resistance and tear strength, thereby improving the reliability of the product.

[Comparative Example 3]

The wire refractory cover of Comparative Example 3 uses only the first curing agent as the curing agent and does not use the second curing agent, and the other conditions are the same as those of the embodiment. The wire refractory cover of Comparative Example 3 lacked curing and all of the characteristics were reduced compared with the examples. That is, in the case of the wire refractory cover according to the present invention, the physical properties of the wire refractory cover are improved by including the expanded graphite but improving the hardenability of the second curing agent.

On the other hand, with respect to 100 parts by weight of the solid silicone rubber, changes in properties were confirmed while changing the content of the curing agent to 10 to 30 parts by weight. According to the present invention, since the composition for a wire refractory cover of the present invention uses a solid silicone rubber, when the total amount of the curing agent is insufficient, the curability is decreased, and the characteristics of the wire refractory cover produced are deteriorated.

On the contrary, when the curing agent is excessively contained in the wire refractory cover composition, the proportion of the solid silicone rubber is relatively reduced, and the characteristics of the wire refractory cover are lowered.

In the present invention, when the content of the curing agent is 15 to 25 parts by weight with respect to 100 parts by weight of the solid silicone rubber, the characteristics of the wire refractory cover to be manufactured can be improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

10: Wires
11: Core
12: Insulation cloth
20: mesh tube
30: Wire refractory cover

Claims (13)

A silicone rubber paste including a first silicone rubber and a solid silicone rubber including a second silicone rubber having a higher softness than the first silicone rubber, a plasticizer and expanded graphite; And curing agents; / RTI >
Wherein the curing agent is selected from the group consisting of a first curing agent comprising bis (2,4-dichlorobenzoyl) peroxide and a silicone oil; And a second curing agent including silica (Silica), tetramethyl tetravinyl cyclotetrasiloxane, octamethylcyclotetrasiloxane, a curing retarder, and a platinum catalyst; Lt; / RTI >
0.02 to 0.04 parts by weight of the plasticizer and 90 to 110 parts by weight of the expanded graphite are contained relative to 100 parts by weight of the silicone rubber,
Wherein the first silicone rubber has a specific gravity of 1.08 to 1.10, a durometer measurement of 32 to 37 Durometer Shore A, a tensile strength of 8 to 11 MPa, an elongation at fracture of 740 to 910%, a tear strength of 24.0 To 31.0 kN / m, a compression set ratio (22 hours, 177 ° C) of 31 to 41%
Wherein the second silicone rubber has a plasticity of 240 or more, a density of 1.1 to 1.2 g / cm 3, a hardness (JIS type A) of 48 to 50, a tensile strength of 9.1 to 9.5 MPa, (JIS # 3) of 510 to 550% and a tear strength of 20 to 25 N / mm. delete The composition according to claim 1, wherein 15 to 25 parts by weight of the curing agent is contained in 100 parts by weight of the silicone rubber. The composition according to claim 1, wherein the weight ratio of the first curing agent to the second curing agent is 0.9: 1 to 1: 0.9. The composition for a wire fireproof cover according to claim 1, wherein the weight ratio of the first silicone rubber and the second silicone rubber is 0.9: 1 to 1: 0.9. At least one linear core capable of transmitting power or signals;
An insulating sheath surrounding the core; And
A wire refractory cover including the composition for a wire fireproof cover according to any one of claims 1 to 5, surrounding the insulating cover; ≪ / RTI > 7. The wire according to claim 6, further comprising a mesh tube disposed between the insulating sheath and the wire refractory cover. Providing a solid silicone rubber comprising a first silicone rubber and a second silicone rubber having a higher softness than the first silicone rubber;
Mixing the solid silicone rubber with a plasticizer and expanded graphite to form a silicone rubber dough;
Mixing the silicone rubber dough with a curing agent to form a sheet form; And
Injecting the silicon rubber dough mixed with the hardening agent into a wire refractory cover using an injection machine; Lt; / RTI >
Wherein the curing agent is a first curing agent comprising bis (2,4-dichlorobenzoyl) peroxide and silicone oil; And a second curing agent including silica (Silica), tetramethyl tetravinyl cyclotetrasiloxane, octamethylcyclotetrasiloxane, a curing retarder, and a platinum catalyst; Lt; / RTI >
0.02 to 0.04 parts by weight of the plasticizer and 90 to 110 parts by weight of the expanded graphite relative to 100 parts by weight of the silicone rubber,
Wherein the first silicone rubber has a specific gravity of 1.08 to 1.10, a durometer measurement of 32 to 37 Durometer Shore A, a tensile strength of 8 to 11 MPa, an elongation at fracture of 740 to 910%, a tear strength of 24.0 To 31.0 kN / m, a compression set ratio (22 hours, 177 ° C) of 31 to 41%
Wherein the second silicone rubber has a plasticity of 240 or more, a density of 1.1 to 1.2 g / cm 3, a hardness (JIS type A) of 48 to 50, a tensile strength of 9.1 to 9.5 MPa, (JIS # 3) is 510 to 550%, and the tear strength is 20 to 25 N / mm. delete The method according to claim 8, wherein 15 to 25 parts by weight of the curing agent is added to 100 parts by weight of the silicone rubber. The method according to claim 8, wherein the weight ratio of the first curing agent to the second curing agent is 0.9: 1 to 1: 0.9. The method according to claim 8, wherein the weight ratio of the first silicone rubber and the second silicone rubber is 0.9: 1 to 1: 0.9. 9. The method of claim 8, wherein the step of injecting the wire-
A primary vulcanization step carried out at 600 to 700 캜;
A secondary vulcanizing step carried out at 210 to 290 占 폚 and carried out in a horizontal rail having a length of 7 to 8 m; And
A tertiary vulcanization step carried out at 180 to 220 캜 and performed in an oven for 3.5 to 4.5 hours; Wherein the cover is made of a metal.

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