High-cold-resistance special cable for control system and processing technology of high-cold-resistance special cable

Abstract

The invention discloses a special cable for a high cold-resistant control system and a processing technology thereof, the cable structure is the special cable for the high cold-resistant control system, the special cable comprises at least two insulating wire cores, a lining layer, a shielding layer and an outer sheath from inside to outside in sequence, each insulating wire core comprises a conductor, a wrapping tape and an insulating layer from inside to outside in sequence, and the inner lining layer is arranged on the outer sheath. The insulating wire cores are mutually twisted, and the twisting gap is filled with a filling rope. The inner side and the outer side of the shielding layer are respectively provided with a wrapping layer, the insulating layer is made of cold-resistant and heat-resistant ethylene propylene rubber materials, and the outer sheath is made of irradiation ethylene propylene rubber materials. According to the application, the scheme that the insulating wire cores are twisted and then the sheath layer is coated on the outer layer is adopted, and the materials of the insulating layer and the outer sheath of the insulating wire cores are made of the ethylene propylene rubber material with high cold resistance, so that the performance of the materials of the insulating layer and the outer sheath can be effectively maintained in a high and cold environment, and the electrical performance of the cable in the high and cold environment is improved.

Description

Technical Field

[0001] The invention relates to a special cable for a highly cold-resistant control system and a processing technology thereof, belonging to the technical field of cable preparation. Background Art

[0002] Systems working in extreme environments have high requirements for the cold resistance of cables. When the temperature changes suddenly, material embrittlement, breakage and cracking of the insulation layer often occur. These problems will cause the electrical performance of the cable to deteriorate, thereby affecting the overall stability and reliability of the control system. In a typical cable structure, the insulation layer and outer sheath material of the conductor and their interlayer uniformity have a great influence on the overall temperature resistance of the cable in cold areas. Specifically, the temperature resistance of the material itself will affect the overall cold resistance temperature of the cable, and the eccentricity of the cold-resistant layer itself will affect the local cold resistance. The main problems currently faced by the industry involve how to improve the cold resistance of materials and how to improve the uniformity of finished products under specific materials. Summary of the invention

[0003] In order to solve the problems in the above-mentioned background technology, the present invention provides a special cable for a highly cold-resistant control system and a processing technology thereof.

[0004] The technical solution to achieve the purpose of the present invention is: a special cable for a highly cold-resistant control system, which includes, from the inside to the outside, an insulating core, an inner lining layer, a shielding layer and an outer sheath, wherein there are at least two insulating cores, and the insulating cores are, from the inside to the outside, a conductor, a wrapping tape and an insulating layer, the insulating cores are twisted with each other, and the twisted gaps are filled with filling ropes; winding layers are respectively provided on the inner and outer sides of the shielding layer, the insulating layer is made of cold-resistant and heat-resistant EPDM rubber material, and the outer sheath is made of irradiated EPDM rubber material.

[0005] The present application discloses a special cable for a highly cold-resistant control system which adopts a scheme in which an insulating core is twisted and then covered with an outer sheath layer. The insulating layer and the outer sheath of the insulating core are made of EPDM rubber material with high cold resistance. When facing a cold environment, the performance of the insulating layer and the outer sheath material can be effectively maintained, thereby improving the electrical performance of the cable in a cold environment.

[0006] As an optional solution of the present application, the filling rope is a hemp rope, the wrapping tape is a thin flame-retardant tape, and the shielding layer is a tinned copper wire braided layer, wherein the thin flame-retardant tape can prevent short circuit and fire when cracks appear in the cable, and the tinned copper wire braided layer can reduce the corrosion of the internal copper wire in low temperature and snow water environment, and can also be used as a shielding layer for electromagnetic interference and radio frequency interference, protecting the internal signal transmission of the cable from the influence of external electromagnetic fields, thereby improving the stability and integrity of the signal.

[0007] The present application also provides a processing technology for the above-mentioned special cable for a high cold-resistant control system, which specifically includes the following steps:

[0008] S1: prepare insulated wire cores and twist them;

[0009] S2: Wrap the inner lining layer and lay the inner shielding layer;

[0010] S3: Extrusion of outer sheath.

[0011] The above processing technology is simple, and the above preparation technology can effectively save preparation time and thus reduce production costs.

[0012] The preparation steps of the insulated wire core are:

[0013] A1: Wrap the tape around the outer layer of the conductor;

[0014] A2: Extruding an insulating layer on the outer layer of the tape;

[0015] As an optional scheme for the above scheme, a 65-stage vulcanizing machine is used in the insulation layer extrusion process in step A2, the insulation layer thickness ranges from 1.0 to 1.2 mm, and the thinnest point thickness ranges from 90% to more than 90% of the average thickness. It has been tested that within this range, the cold resistance of the cable can be effectively guaranteed and its performance uniformity can be improved.

[0016] The S3 extrusion process uses a semi-extrusion die, and the outer sheath extrusion process uses a 120 extrusion sheath and a double-thread screw. The thickness of the outer sheath at the thinnest point is not less than 85% of the average thickness. After extrusion, the method of first irradiation and then cooling is used for curing.

[0017] In the above extrusion process, a double-threaded screw and a semi-extrusion die are used. This combination can effectively prevent the adhesion of the sheath or the cable core when extruding rubber materials. The sheath is easier to peel off, the eccentricity of the sheath is lower, the roundness of the cable is better, the structure is more compact, and the outer diameter control is more precise. The out-of-roundness can be controlled to about 6%. The electrical performance of the cable is better under this out-of-roundness.

[0018] As an optional solution of the present application, the semi-extrusion die

[0019] Core diameter d1 = sheath front diameter d0 ± 0.2 mm; core sizing area l = (0.8 ~ 1.0) * d1, core outer cone angle α2 = (30 ~ 40) °;

[0020] The inner cone angle of the die sleeve is δ = (35-45)°;

[0021] The inner diameter of the die sleeve d3 = the nominal diameter of the finished product d2 + (0.11 ~ 0.13) mm;

[0022] Die sleeve sizing area l1 = (1.2 ~ 1.3) * d3.

[0023] In the actual production process, oversized core and sleeve will lead to uneven extrusion thickness, poor roundness and large outer diameter fluctuations. The outer taper angle of the core and the inner taper angle of the sleeve have a significant impact on the extrusion pressure. The angle between the core and the sleeve is the die angle. When the die angle is too large, it will lead to excessive extrusion pressure, material accumulation in the sleeve, resulting in die jamming, which will seriously affect production continuity.

[0024] Furthermore, in order to obtain optimal production parameters, the outer cone angle of the mold core is α2=36°, and the inner cone angle of the mold sleeve is δ=38°.

[0025] During the extrusion process of the outer sheath, the extrusion temperature is 100-135°C. After the extrusion is completed, it is first irradiated and then cooled. The cooling tank is ≥10m, the irradiation parameters are a dose of 0.8-0.9m / min / mA, an irradiation energy of 3.0MeV, and a beam current of 20mA. The irradiation parameters will affect the mechanical strength, cold resistance and anti-aging properties of the extruded material, and effectively avoid the embrittlement of the material at low temperatures, thereby improving the tolerance of the outer sheath in a high-cold environment and extending the product life.

[0026] The formula of the insulating layer is 100 parts of EPDM rubber matrix, 50 parts of talc, 60 parts of calcium carbonate, 8 parts of paraffin oil, 1 part of silane, 5 parts of paraffin, and 5 parts of zinc oxide. The calcium carbonate and the above ingredients are beneficial to improving the wear resistance and tear resistance of the finished product. The silane component is beneficial to improving the interface bonding performance between the inorganic filler and the organic polymer, and further improving the tear resistance of the product. The synergistic effect of the two can improve the material's resistance to cracking in low temperature environments, thereby extending the product life.

[0027] The formula of the outer sheath is 80 parts of chlorinated polyethylene, 20 parts of ethylene-vinyl acetate copolymer, 2 parts of ethylene-vinyl acetate copolymer (vinyl acetate content is greater than 28%), 40 parts of talc, 60 parts of modified magnesium hydroxide, 8 parts of magnesium oxide, 1.5 parts of silane silane coupling agent, 20 parts of carbon black, 10 parts of white carbon black, and 15 parts of dioctyl adipate. Among the above materials, ethylene-vinyl acetate copolymer and dioctyl adipate can both improve the overall flexibility, impact resistance and low-temperature brittleness resistance of the material. Between the two, ethylene-vinyl acetate copolymer has a flexible long-chain structure, which is beneficial to dioctyl adipate. The short-chain structure of octyl ester is inserted in between, which effectively weakens the van der Waals force and other secondary bonds between the long chains of the polymer. The role of this combination is: first, it makes the polymer chain easier to slide, thereby reducing the overall glass transition temperature of the material and increasing the softness and ductility of the material; second, the design of the short-chain structure inserted into the long-chain structure is conducive to reducing the overall hardness and modulus of the material, reducing the cohesive energy density between the chain segments, making the material easier to deform, and improving the overall fluidity of the material at low temperatures. In a low-temperature environment, the cooperation between the two can effectively prevent the material from becoming brittle, and its cold resistance is higher than that of general materials.

[0028] By adopting the above technical solution, the present invention has the following beneficial effects:

[0029] (1) The present application discloses a special cable for a highly cold-resistant control system that adopts a scheme in which an insulating core is twisted and then covered with a sheath layer. The insulating layer and the outer sheath of the insulating core are made of EPDM rubber material with high cold resistance. When facing a cold environment, the performance of the insulating layer and the outer sheath material can be effectively maintained, thereby improving the electrical performance of the cable in a cold environment.

[0030] (2) The present application discloses a special cable for a highly cold-resistant control system that uses a thin flame-retardant tape as a wrapping tape and a tinned copper wire braided layer as a shielding layer. The medium-thin flame-retardant tape can prevent short circuit fire when cracks appear in the cable. The tinned copper wire braided layer can reduce the corrosion of the internal copper wire in low temperature and snow and water environments. It can also serve as a shielding layer for electromagnetic interference and radio frequency interference, protecting the internal signal transmission of the cable from the influence of external electromagnetic fields, thereby improving the stability and integrity of the signal.

[0031] (3) The processing technology of the special cable for a highly cold-resistant control system of the present application is simple, which is conducive to reducing production costs.

[0032] (4) The processing technology of a special cable for a highly cold-resistant control system in the present application formulates the extrusion method and thickness of each layer used in the extrusion process, which can effectively prevent adhesion during the extrusion process. It is easier to peel off after extrusion, and the final product has better roundness, more compact structure, and more stable electrical performance.

[0033] (5) The processing technology of a special cable for a highly cold-resistant control system in the present application specifies the matching relationship between the mold core and the mold sleeve, strictly limits its mold angle, and effectively prevents the mold jamming problem caused by the accumulation of extrusion pressure. Compared with other extrusion structures, its production continuity is better.

[0034] (6) The processing technology of a special cable for a highly cold-resistant control system in the present application specifies the extrusion temperature and irradiation parameters during the extrusion process, which can effectively balance the mechanical properties, cold resistance and anti-aging properties of the material and effectively avoid the low-temperature embrittlement of the material.

[0035] (7) The calcium carbonate and in the insulation layer formula of a special cable for a highly cold-resistant control system of the present application are beneficial to improving the wear resistance and tear resistance of the finished product, and the silane component is beneficial to improving the interface bonding performance between the inorganic filler and the organic polymer, further improving the tear resistance of the product. The synergistic effect of the two can improve the material's resistance to cracking in a low temperature environment, thereby extending the product life.

[0036] (8) In the outer sheath formula of a special cable for a highly cold-resistant control system in the present application, the long and short chains of ethylene-vinyl acetate copolymer and dioctyl adipate can be effectively interlaced and matched. The short chain of dioctyl adipate can be inserted into the flexible long chain structure of ethylene-vinyl acetate copolymer, making the long chain of ethylene-vinyl acetate copolymer easier to slide, thereby effectively reducing the overall glass transition temperature of the outer sheath, increasing the softness and ductility of the material and reducing the overall hardness and modulus of the material, thereby improving the overall fluidity of the material at low temperatures. The cooperation between the two can effectively prevent the material from becoming brittle, and its cold resistance is higher than that of general materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments and in conjunction with the accompanying drawings, wherein

[0038] Figure 1 It is a structural schematic diagram of the present invention;

[0039] Figure 2 A schematic diagram of a semi-extrusion mold core and a semi-extrusion mold sleeve of the present invention;

[0040] Figure 3 It is a schematic diagram of the production process of the present invention;

[0041] The reference numerals in the accompanying drawings are:

[0042] Insulated wire core 1, conductor 11, wrapping tape 12, insulating layer 13, shielding layer 2, outer sheath 3, filling rope 4, and wrapping layer 5. DETAILED DESCRIPTION

[0043] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0047] In the description of the embodiments of the present invention, it should be understood that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is conventionally placed when used, or are the orientations or positional relationships conventionally understood by those skilled in the art. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0048] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The present invention is further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the scope of protection of the present invention.

[0049] (Example 1)

[0050] Figure 1 This is a simplified structural diagram of a special cable for a highly cold-resistant control system of the present application, which specifically includes an insulating core 1, a shielding layer 2 and an outer sheath 3 from the inside to the outside, wherein there are at least two insulating cores 1, and the insulating cores 1 include a conductor 11, a wrapping tape 12 and an insulating layer 13 from the inside to the outside, the insulating cores 1 are twisted with each other, and the twisted gaps are filled with filling ropes 4; the shielding layer 2 is provided with a wrapping layer 5 on both the inner and outer sides, the insulating layer 13 is made of cold-resistant and heat-resistant EPDM rubber material, and the outer sheath 3 is made of irradiated EPDM rubber material.

[0051] The filling rope 4 is a hemp rope, the wrapping tape 12 is a thin flame-retardant tape, and the shielding layer 2 is a tinned copper wire braided layer.

[0052] In the above structure, the braiding density of the tinned copper wire braided layer of the shielding layer 2 is ≥85%.

[0053] In the above structure, in order to improve the resistance of the shield layer 2 and the outer sheath 3 which are prone to cracking due to severe cold, it is necessary to adjust their components.

[0054] The formula of the insulating layer is 100 parts of EPDM rubber matrix, 50 parts of talcum powder, 60 parts of calcium carbonate, 8 parts of paraffin oil, 1 part of silane, 5 parts of paraffin and 5 parts of zinc oxide.

[0055] The formula of the outer sheath is 80 parts of chlorinated polyethylene, 20 parts of ethylene-vinyl acetate copolymer, 2 parts of ethylene-vinyl acetate copolymer with a vinyl acetate content greater than 28%, 40 parts of talc, 60 parts of modified magnesium hydroxide, 8 parts of magnesium oxide, 1.5 parts of silane silane coupling agent, 20 parts of carbon black, 10 parts of white carbon black, and 15 parts of DOA.

[0056] Among the above ingredients, there is a matching relationship between the ingredients. The calcium carbonate in the insulation layer formula is beneficial to improving the wear resistance and tear resistance of the insulation layer, and the silane component is beneficial to improving the interface bonding performance between the inorganic filler and the organic polymer; the long and short chains of ethylene-vinyl acetate copolymer and dioctyl adipate in the components of the outer sheath can be effectively interlaced and matched, which can reduce the overall glass transition temperature of the outer sheath and help increase its overall softness and ductility. The two are related. The outer sheath is arranged outside the insulation layer. It is generally believed that the outer sheath is destroyed first and then the insulation layer is broken.

[0057] In formula design, the vinyl acetate content has a great influence on the overall performance of ethylene-vinyl acetate copolymer and outer sheath. The vinyl acetate content is controlled between 28 and 40%. Increasing the vinyl acetate content is beneficial to improving the flexibility, impact resistance and low-temperature crack resistance of the material, while improving the adhesion and processing fluidity of the material. The specific fine content needs to be set according to the working environment parameters.

[0058] After testing, using the above formula, the temperature resistance range of the insulation layer is -50 ~ 90 ℃, and the insulation resistance is ≥ 500MΩ·km.

[0059] Figure 3 This is a schematic diagram of the production process of a special cable for a highly cold-resistant control system of the present application, and the specific production sequence is conductor, insulation, cabling, shielding, wrapping, outer sheath, irradiation, cooling, and winding.

[0060] The number of insulated wire cores is 19 and the nominal cross-sectional area of ​​the conductor is 2.5mm 2 As the target parameter, the following parameters can be obtained by testing the tube extrusion, extrusion and semi-extrusion dies under the above formula:

[0061]

[0062] It can be seen that the eccentricity of the product is lower when the semi-extrusion extrusion method is adopted, so the semi-extrusion structure design is adopted, which has

[0063]

[0064] The body parameters and test results are as follows:

[0065] According to the test, when the outer cone angle of the mold core α2=36° and the inner cone angle of the mold sleeve δ=38°, the eccentricity reaches 6% and the cable appearance is optimal.

[0066] Its specific structure is as follows Figure 2 As shown, a is a semi-extrusion mold core structure; b is a semi-extrusion mold sleeve structure.

[0067] The processing technology of a special cable for a high cold-resistant control system of the present application comprises the following steps:

[0068] S1: preparing an insulated wire core 1 and twisting it;

[0069] S2: Wrap the inner lining layer 2 and lay the inner shielding layer 2;

[0070] S3: extrusion of outer sheath 3;

[0071] Specifically, the preparation steps of the insulated wire core 1 are:

[0072] A1: Wrap the tape 12 around the outer layer of the conductor 11;

[0073] A2: Extruding an insulating layer 13 on the outer layer of the wrapping tape 12;

[0074] In the step A2, a 65-degree continuous vulcanizing machine is used in the extrusion process of the insulating layer 13, and the thickness of the insulating layer ranges from 1.0 to 1.2 mm, and the thickness range of the thinnest point is more than 90% of the average thickness.

[0075] A semi-extrusion die is used in the S3 extrusion process, a 120 extrusion sheath and a double-thread screw are used in the extrusion process of the outer sheath 3, the extrusion temperature is 100°C, 113°C, 126°C, 132°C, 136°C, 135°C, the thickness of the outer sheath 3 at the thinnest point is not less than 85% of the average thickness, and after extrusion, solidification is performed by irradiation followed by cooling.

[0076] The extrusion temperature of the outer sheath 3 during extrusion is 100-135° C. After extrusion, the irradiation parameters are a dose of 0.8-0.9 m / min / mA, an irradiation energy of 3.0 MeV, and a beam current of 20 mA.

[0077] During the above operation, the sheath is extruded and passed through the cooling water trough for at least 10 meters to ensure that the cable is fully cooled. When winding the cable sheath, a mixture of talcum powder and rubber isolation agent (the ratio of talcum powder and rubber isolation agent is 1:2) is evenly applied on the surface of the cable sheath to prevent the cable from sticking after winding.

[0078] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A special cable for a highly cold-resistant control system, characterized in that: The invention comprises, from the inside to the outside, an insulating core (1), a shielding layer (2) and an outer sheath (3), wherein the number of insulating cores (1) is at least two, and the insulating cores (1) comprise, from the inside to the outside, a conductor (11), a wrapping tape (12) and an insulating layer (13), the insulating cores (1) are twisted together, and the twisted gaps are filled with a filling rope (4); the shielding layer (2) is provided with a wrapping layer (5) on both the inside and outside sides, respectively, the insulating layer (13) is made of a cold-resistant and heat-resistant ethylene-propylene rubber material, and the outer sheath (3) is made of an irradiated ethylene-propylene rubber material.

2. The special cable for a highly cold-resistant control system according to claim 1 is characterized in that: The filling rope (4) is a hemp rope, the wrapping tape (12) is a thin flame-retardant tape, and the shielding layer (2) is a tinned copper wire braided layer.

3. The processing technology of a special cable for a highly cold-resistant control system according to claim 1 or 2, characterized in that The following steps are involved: S1: preparing an insulated wire core (1) and twisting it; S2: Wrapping the first wrapping layer (5) and laying the inner shielding layer (2) and then wrapping the second wrapping layer (5); S3: Extrusion of the outer sheath (3).

4. The processing technology of a special cable for a high cold-resistant control system according to claim 3 is characterized in that The steps for preparing the insulated wire core (1) are as follows: A1: Wrapping a tape (12) around the outer layer of the conductor (11); A2: Extruding an insulating layer (13) on the outer layer of the wrapping tape (12); In the step A2, a 65-degree continuous vulcanization machine is used in the extrusion process of the insulating layer (13), the thickness of the insulating layer ranges from 1.0 to 1.2 mm, and the thickness range of the thinnest point is more than 90% of the average thickness.

5. The processing technology of a special cable for a highly cold-resistant control system according to claim 3 is characterized in that A semi-extrusion die is used in the S3 extrusion process, a 120 extrusion sheath and a double-thread screw are used in the extrusion process of the outer sheath (3), the thickness of the thinnest point of the outer sheath (3) is not less than 85% of the average thickness, and after extrusion, solidification is performed by first irradiating and then fully cooling in a cooling water tank.

6. The processing technology of a special cable for a highly cold-resistant control system according to claim 5 is characterized in that The semi-extrusion die Core diameter d1 = sheath front diameter d0 ± 0.2 mm; core sizing area l = (0.8 ~ 1.0) * d1, core outer cone angle α2 = (30 ~ 40) °; Die sleeve inner cone angle δ = (35 ~ 45) °; The inner diameter of the die sleeve d3 = the nominal diameter of the finished product d2 + (0.11 ~ 0.13) mm; Die sleeve sizing area l1 = (1.2 ~ 1.3) * d3.

7. The processing technology of a special cable for a highly cold-resistant control system according to claim 5 is characterized in that The outer cone angle of the mold core is α2=36°, and the inner cone angle of the mold sleeve is δ=38°.

8. The processing technology of a special cable for a highly cold-resistant control system according to claim 5 is characterized in that: The extrusion temperature of the outer sheath (3) during the extrusion process is 100-135° C. After the extrusion is completed, the irradiation parameters are a dose of 0.8-0.9 m / min / mA, an irradiation energy of 3.0 MeV, a beam current of 20 mA, and after the irradiation is completed, it passes through a cooling tank for ≥10 m.

9. The special cable for a highly cold-resistant control system according to claim 4, characterized in that: The formula of the insulating layer is 100 parts of EPDM rubber matrix, 50 parts of talcum powder, 60 parts of calcium carbonate, 8 parts of paraffin oil, 1 part of silane, 5 parts of paraffin and 5 parts of zinc oxide.

10. The special cable for a highly cold-resistant control system according to claim 1, characterized in that: The formula of the outer sheath is 80 parts of chlorinated polyethylene, 20 parts of ethylene-vinyl acetate copolymer, 2 parts of ethylene-vinyl acetate copolymer, 40 parts of talc, 60 parts of modified magnesium hydroxide, 8 parts of magnesium oxide, 1.5 parts of silane silane coupling agent, 20 parts of carbon black, 10 parts of white carbon black, and 15 parts of dioctyl adipate.

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