High-voltage flexible cable for shield tunneling machine and preparation process of high-voltage flexible cable

Abstract

The invention relates to the technical field of cables, in particular to a high-voltage flexible cable for a shield tunneling machine and a preparation process of the high-voltage flexible cable. The high-voltage flexible cable for the shield tunneling machine comprises a cable core, an inner protective layer, a tensile reinforced braid layer and an outer protective layer which are sequentially arranged from inside to outside, the tensile reinforced braid layer is made of tensile toughened aramid fibers, and the outer protective layer is made of wear-resistant flexible sheath materials. The tensile toughened aramid yarn has good tensile performance and bending resistance, can effectively bear tensile force borne by the cable in the using process, and adapts to frequent bending of the cable. The flexible wear-resistant composite filler in the wear-resistant flexible sheath material combines the flame retardancy and wear resistance of hydroxyapatite and the flexibility and tensile strength of reed fibers, so that the tensile strength, flame retardancy and wear resistance of the flexible cable sheath for the shield tunneling machine can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of cables, and in particular to a high-voltage flexible cable for a shield machine and a preparation process thereof. Background Art

[0002] The shield machine is a kind of mechanical equipment for underground tunneling, which is suitable for modern transportation, underground engineering, mining, water conservancy engineering, municipal construction, electrical communication and other fields. The shield machine excavates in tunnels in harsh environments such as high temperature, humidity, and gravel. As the core supporting component of the shield machine, the special cable for the shield machine not only requires excellent insulation physical and mechanical properties and electrical properties, but also requires the cable sheath to have excellent physical and mechanical properties and crack resistance. In the existing technology, high-performance sheath materials are usually used and a fiber braided reinforcement layer is added to embed the extruded outer sheath to improve the overall performance of the cable sheath.

[0003] At present, the commonly used fiber braiding reinforcement material is mainly aramid yarn. Although aramid yarn has high strength and heat resistance, it is composed of a highly conjugated rigid structure, with a smooth surface and high inertness. It has poor interfacial adhesion with the inner sheath, outer sheath and other sheath materials of the cable, which can easily lead to delamination and debonding between the fiber braiding reinforcement layer and other sheath layers during the use of the cable, affecting the overall structural stability and mechanical properties such as tensile strength and bending resistance of the cable.

[0004] Existing high-performance sheath materials are mainly obtained by adding fillers (such as kaolin, zinc oxide, hydroxylated apatite and white carbon black, etc.), flame retardants, antioxidants and other additives to rubber base materials (such as polyvinyl chloride, butyl rubber and EPDM rubber, etc.) to give the rubber base materials corresponding wear resistance, flame retardancy and aging resistance. Among them, although hydroxylated apatite has high hardness, strength and flame retardancy, adding it to the sheath material of the cable can improve the wear resistance and flame retardancy of the sheath material, but hydroxyapatite itself is a brittle material. Excessive addition to the sheath material will reduce the toughness of the sheath material. In addition, due to the presence of hydroxyl groups, hydroxyapatite has poor compatibility with the rubber base material of the sheath material. Therefore, when the cable is deformed by bending, stretching, etc., cracks are likely to occur at the interface between the hydroxyapatite particles and the rubber base material, which will then expand and cause the sheath material to be damaged, affecting the reliability and service life of the cable.

[0005] In addition, reed is a widely distributed natural plant, a renewable resource, and has a certain strength and modulus, which can improve the tensile strength and flexibility of the cable sheath material to a certain extent. However, reed fiber has poor flame retardancy and contains a large amount of hydroxyl groups, which are hydrophilic, reducing the interfacial bonding strength between the reed fiber and the rubber substrate, affecting the overall performance of the sheath material, and thus the safety of cable use. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a high-voltage flexible cable for a shield machine and a preparation process thereof.

[0007] A high-voltage flexible cable for a shield machine comprises a cable core, an inner sheath, a tensile reinforcement braided layer and an outer sheath arranged in sequence from the inside to the outside, the cable core is composed of three main line cores and three ground line cores, the centers of the three main line cores are arranged in an equilateral triangle, and the three ground line cores are respectively arranged in the gap between every two adjacent main line cores; The raw material of the tensile reinforcement braided layer is tensile toughened aramid yarn, and the raw material of the outer sheath is wear-resistant flexible sheath material; The tensile toughened aramid yarn is prepared by using silica particle grafted aramid yarn and methyl methacrylate as raw materials, using azobisisobutyronitrile as an initiator, and grafting polymethyl methacrylate on the surface of the silica particle grafted aramid yarn; The silica particle grafted aramid fiber is obtained by loading silica particles on the surface of the modified aramid fiber after the aramid fiber is modified by a silane coupling agent. The raw materials of the wear-resistant flexible sheath material are 80 to 120 parts by weight of rubber base material, 10 to 30 parts by weight of flexible wear-resistant composite filler, 1 to 5 parts by weight of plasticizer, 2 to 6 parts by weight of vulcanizer, 2 to 5 parts by weight of antioxidant, 1 to 7 parts by weight of coupling agent KH-550, 1 to 3 parts by weight of antioxidant and 1 to 3 parts by weight of accelerator; The flexible and wear-resistant composite filler is obtained by hydrophobically modifying hydroxyapatite-loaded reed fiber with a silane coupling agent KH-550. The hydroxyapatite-loaded reed fiber is obtained by forming hydroxyapatite crystals on the surface of the reed fiber using soluble calcium salt and soluble phosphate as raw materials.

[0008] Furthermore, the raw material of the inner protective layer is the inner sheath material, and the inner sheath material includes a rubber base material, silicon dioxide, a vulcanizing agent, an antioxidant, a silane coupling agent KH-550 and an antioxidant.

[0009] Furthermore, the rubber substrate is at least one of chloroprene rubber, styrene-butadiene rubber or chlorinated polyethylene.

[0010] Furthermore, the preparation of silica particle grafted aramid fibers specifically includes the following steps: The aramid yarn is soaked in anhydrous ethanol and ultrasonically cleaned for 20 to 30 minutes, and then dried to obtain the aramid yarn with surface oil and impurities removed. The aramid yarn with surface oil and impurities removed is placed in a sodium hydroxide solution with a mass fraction of 5 to 10%, and soaked at 60 to 70° C. for 1 to 2 hours. Subsequently, the soaked aramid yarn is rinsed with deionized water until it is neutral, and dried to obtain the pretreated aramid yarn. The pretreated aramid yarn is immersed in the modified solution, ultrasonically dispersed for 10 to 30 minutes, the pH is adjusted to 4 to 5, and reacted at 56 to 72° C. for 1 to 2 hours. After the reaction is completed, the aramid yarn after the reaction is washed with ethanol and dried to obtain the modified aramid yarn; 1 to 3 parts by weight of modified aramid yarns are immersed in a reactor filled with 150 to 360 parts by weight of anhydrous ethanol, and aqueous ammonia is added to the reactor, and the pH is adjusted to 9 to 10, and ultrasonic dispersion is performed for 10 to 20 minutes. Subsequently, magnetic stirring is performed at 50 to 60°C, and 50 to 80 parts by weight of reaction liquid are slowly dripped into the reaction solution during the stirring process. After the reaction solution is dripped, the reaction is continued by stirring for 4 to 6 hours. After the reaction is completed, the modified aramid yarns are washed with ethanol, and finally, the aramid yarns are cured at 90 to 105°C for 1 to 2 hours to obtain silica particle grafted aramid yarns.

[0011] Furthermore, the modified solution is prepared by mixing the silane coupling agent KH-550 and an ethanol solution having a volume fraction of 90% in a mass ratio of (2-5):100.

[0012] Furthermore, the reaction solution is prepared by mixing ethyl orthosilicate and an ethanol solution with a volume fraction of 70% in a mass ratio of (5-10):100.

[0013] Furthermore, the preparation of the tensile toughened aramid yarn specifically includes the following steps: 1-5 parts by weight of silica particle grafted aramid yarn, 4-9 parts by weight of methyl methacrylate and 0.02-0.05 parts by weight of azobisisobutyronitrile are added to 200-400 parts by weight of toluene, and the pH is adjusted to 5-7. Under a nitrogen atmosphere, the mixture is stirred in an oil bath at 60-80°C for 3-6 hours. After the reaction, the mixture is cooled to room temperature. The treated silica particle grafted aramid yarn is filtered, washed with toluene, washed with ethanol and dried to obtain a tensile toughened aramid yarn.

[0014] Furthermore, the preparation of the flexible and wear-resistant composite filler specifically includes the following steps: The reed fiber is immersed in a sodium hydroxide solution with a mass fraction of 5 to 10% for alkalization treatment, and then washed with deionized water and dried to obtain the alkalized reed fiber; Dissolve a soluble calcium salt and a soluble phosphate in deionized water to prepare a calcium salt solution with a concentration of 0.05-0.1 mol / L and a phosphate solution with a concentration of 0.3-1 mol / L, add 1-3 parts by weight of alkalized reed fiber to 200-600 parts by weight of the calcium salt solution, stir evenly, slowly drop 20-60 parts by weight of the phosphate solution under stirring, adjust the pH of the solution to 8-10 with ammonia water after the phosphate solution is added, stir in a water bath at 30-75° C. for 1-3 hours, age for 24-36 hours after the stirring is completed, and then wash, filter, dry and crush to obtain hydroxylated apatite-loaded reed fiber; Hydroxylated apatite-loaded reed fiber is added to an ethanol solution with a volume fraction of 70% to prepare a hydroxylated apatite-loaded reed fiber dispersion solution with a hydroxylated apatite-loaded reed fiber concentration of 1 to 3 g / L. Silane coupling agent KH-550 is added to the hydroxylated apatite-loaded reed fiber dispersion solution in an amount of 3 to 5% of the mass of the hydroxylated apatite-loaded reed fiber dispersion solution. The mixture is stirred and reacted at 40 to 70° C. for 1 to 3 hours. Subsequently, the mixture is filtered and dried to obtain a flexible and wear-resistant composite filler.

[0015] Furthermore, the plasticizer is at least one of dioctyl phthalate, dibutyl phthalate, and diisononyl phthalate; the vulcanizer is at least one of tert-butyl perbenzoate, diisopropylbenzene peroxide, and tert-butylisopropylbenzene peroxide; the antioxidant is at least one of antioxidant A, antioxidant H, antioxidant ODA, or antioxidant 4020; the antioxidant is at least one of antioxidant TPP, antioxidant 1010, antioxidant 1076, or antioxidant 168; and the accelerator is at least one of accelerator D, accelerator M, or accelerator PZ.

[0016] A preparation process of a high-voltage flexible cable for a shield machine comprises the following steps: S1: uniformly mixing the raw materials of the inner sheath material, kneading, extruding and granulating to obtain the inner sheath material; S2: uniformly mixing the raw materials of the wear-resistant flexible sheath material, kneading, extruding and granulating to obtain the wear-resistant flexible sheath material; S3: Extrude a layer of inner sheath material outside the cable core to form an inner sheath, and then weave a layer of tensile reinforcement braided layer with tensile toughening aramid yarn outside the inner sheath, with a braiding density of 20-35% and a braiding section diameter ratio of 2-4.5; S4: A layer of wear-resistant flexible sheath material is extruded outside the tensile reinforcement braided layer to form an outer sheath to obtain a high-voltage flexible cable for a shield machine.

[0017] The present invention has the following advantages: 1. In the present invention, by loading silica particles on the surface of aramid yarn, the obtained silica particle grafted aramid yarn can not only utilize the silica particles to increase the surface area and roughness of the aramid yarn surface, which is beneficial to improve the interface bonding performance between the aramid yarn and the rubber substrate in the sheath, but also the silica particles in the silica particle grafted aramid yarn can enhance the tensile properties of the aramid yarn, thereby improving the tensile strength and bending resistance of the high-voltage flexible cable for the shield machine.

[0018] 2. In the present invention, azobisisobutyronitrile is used as an initiator to initiate a free radical polymerization reaction of methyl methacrylate on the surface of the silica particles grafted aramid fiber, and polymethyl methacrylate is grafted onto the surface of the aramid fiber to obtain a tensile toughened aramid fiber. The flexibility and elasticity of polymethyl methacrylate can further enhance the tensile strength and bending resistance of the silica particle grafted aramid fiber, so that when the high-voltage flexible cable for the shield machine is subjected to external force, it can effectively withstand the tensile force to which the high-voltage flexible cable for the shield machine is subjected during use, adapt to frequent bending, reduce the risk of damage to the high-voltage flexible cable for the shield machine due to stretching, and improve the reliability and service life of the high-voltage flexible cable for the shield machine.

[0019] 3. In the present invention, active groups on the surface of reed fiber, such as carboxyl and hydroxyl, are used as nucleation sites to allow hydroxylated apatite to grow and load on the fiber surface of reed fiber. The obtained hydroxylated apatite-loaded reed fiber combines the wear resistance and flame retardancy of hydroxylated apatite with the flexibility and tensile resistance of reed fiber, and has good mechanical properties, wear resistance and flame retardancy. In addition, by hydrophobic modification treatment with silane coupling agent KH-550, the hydroxyl groups on the surface of hydroxylated apatite-loaded reed fiber and the silanol groups generated after hydrolysis of silane coupling agent KH-550 undergo condensation reaction. The obtained flexible and wear-resistant composite filler is better dispersed in the rubber substrate after surface hydrophobization, thereby improving the tensile resistance, flame retardancy and wear resistance of the high-voltage flexible cable for shield machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The structure diagram of the high-voltage flexible cable for a shield machine prepared in the embodiments and comparative examples of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0022] Example 1 A preparation process of a high-voltage flexible cable for a shield machine comprises the following steps: S1: 100 parts by weight of chlorinated polyethylene, 20 parts by weight of silicon dioxide, 5 parts by weight of dibutyl phthalate, 3 parts by weight of antioxidant A, 5 parts by weight of silane coupling agent KH-550 and 3 parts by weight of antioxidant 1010 are uniformly mixed, kneaded, extruded and granulated at an extrusion temperature of 200° C. to obtain an inner sheath material; S2: 100 parts by weight of chlorinated polyethylene, 30 parts by weight of flexible wear-resistant composite filler, 5 parts by weight of dibutyl phthalate, 6 parts by weight of diisopropylbenzene peroxide, 2 parts by weight of antioxidant A, 2 parts by weight of antioxidant H, 7 parts by weight of coupling agent KH-550, 3 parts by weight of antioxidant 1010, and 3 parts by weight of accelerator M are mixed uniformly, kneaded, extruded, and granulated at an extrusion temperature of 200° C. to obtain a wear-resistant flexible sheath material; S3: Extrude a layer of inner sheath material outside the cable core to form an inner sheath with a nominal thickness of 3mm. Then, weave a tensile reinforcement braided layer with tensile toughening aramid yarn outside the inner sheath with a braiding density of 30% and a braiding pitch ratio of 3; S4: A layer of wear-resistant flexible sheath material is extruded outside the tensile reinforcement braided layer to form an outer sheath with a nominal thickness of 6 mm to obtain a high-voltage flexible cable for a shield machine, such as Figure 1 shown.

[0023] Among them, the preparation of tensile-resistant and toughened aramid yarn is as follows: 5 parts by weight of silica particle grafted aramid yarn, 9 parts by weight of methyl methacrylate and 0.05 parts by weight of azobisisobutyronitrile are added to 400 parts by weight of toluene, the pH is adjusted to 5, and the reaction is stirred in a 70°C oil bath under a nitrogen atmosphere for 6 hours. After the reaction is completed, the temperature is cooled to room temperature. The treated silica particle grafted aramid yarn is filtered, washed with toluene, washed with ethanol and dried in turn to obtain tensile-resistant and toughened aramid yarn.

[0024] The preparation of silica particle grafted aramid fibers is as follows: the aramid fibers are immersed in anhydrous ethanol for ultrasonic cleaning for 30 minutes, and then dried to obtain aramid fibers with surface oil and impurities removed; the aramid fibers with surface oil and impurities removed are placed in a 10% by mass sodium hydroxide solution and immersed at 60° C. for 2 hours; then, the immersed aramid fibers are rinsed with deionized water until neutral, and then dried to obtain pretreated aramid fibers; The pretreated aramid yarn was immersed in a modification solution, which was prepared by a mass ratio of 5:100 of a silane coupling agent KH-550 and a 90% ethanol solution, and ultrasonically dispersed for 30 minutes, and the pH was adjusted to 5. The aramid yarn was reacted at 60°C for 2 hours. After the reaction was completed, the aramid yarn was washed with ethanol and dried to obtain a modified aramid yarn. 3 parts by weight of modified aramid yarn were immersed in a reactor filled with 360 parts by weight of anhydrous ethanol, and ammonia water was added to the reactor, the pH was adjusted to 10, and ultrasonic dispersion was performed for 20 minutes. Subsequently, magnetic stirring was performed at 60°C, and 80 parts by weight of reaction liquid was slowly dripped into the reaction solution during the stirring process. The reaction liquid was composed of tetraethyl orthosilicate and 70% ethanol solution by volume in a mass ratio of 8:100. After the reaction liquid was added, the reaction was continued with stirring for 6 hours. After the reaction was completed, the modified aramid yarn was washed with ethanol, and finally, it was cured at 100°C for 2 hours to obtain silica particle grafted aramid yarn.

[0025] The flexible and wear-resistant composite filler is prepared by immersing the reed fiber in a sodium hydroxide solution with a mass fraction of 10% for alkalization treatment, and then washing with deionized water and drying to obtain the alkalized reed fiber; Calcium chloride and diammonium hydrogen phosphate were dissolved in deionized water to prepare a calcium chloride solution with a concentration of 0.05 mol / L and a diammonium hydrogen phosphate solution with a concentration of 0.3 mol / L, 3 parts by weight of alkalized reed fiber were added to 500 parts by weight of the calcium chloride solution, and stirred evenly. Then, 60 parts by weight of the diammonium hydrogen phosphate solution were slowly added dropwise under stirring. After the diammonium hydrogen phosphate solution was added dropwise, the pH value of the solution was adjusted to 10 with ammonia water, and stirred in a water bath at 60° C. for 3 h. After the stirring was completed, the solution was aged for 36 h, and then washed, filtered, dried and crushed to obtain hydroxylated apatite-loaded reed fiber; Hydroxylated apatite-loaded reed fiber was added to an ethanol solution with a volume fraction of 70% to prepare a hydroxylated apatite-loaded reed fiber dispersion solution with a hydroxylated apatite-loaded reed fiber concentration of 3 g / L. Silane coupling agent KH-550 was added to the hydroxylated apatite-loaded reed fiber dispersion solution in an amount of 5% of the mass of the hydroxylated apatite-loaded reed fiber dispersion solution. The reaction was stirred at 70°C for 3 hours, and then, the mixture was filtered and dried to obtain a flexible and wear-resistant composite filler.

[0026] Example 2 A preparation process of a high-voltage flexible cable for a shield machine comprises the following steps: S1: 100 parts by weight of chlorinated polyethylene, 20 parts by weight of silicon dioxide, 5 parts by weight of dibutyl phthalate, 3 parts by weight of antioxidant A, 5 parts by weight of silane coupling agent KH-550 and 3 parts by weight of antioxidant 1010 are uniformly mixed, kneaded, extruded and granulated at an extrusion temperature of 180° C. to obtain an inner sheath material; S2: 100 parts by weight of chlorinated polyethylene, 30 parts by weight of flexible wear-resistant composite filler, 5 parts by weight of dibutyl phthalate, 6 parts by weight of diisopropylbenzene peroxide, 2 parts by weight of antioxidant A, 2 parts by weight of antioxidant H, 7 parts by weight of coupling agent KH-550, 3 parts by weight of antioxidant 1010, and 3 parts by weight of accelerator M are mixed uniformly, kneaded, extruded, and granulated at an extrusion temperature of 180° C. to obtain a wear-resistant flexible sheath material; S3: Extrude a layer of inner sheath material outside the cable core to form an inner sheath with a nominal thickness of 3mm. Then, weave a tensile reinforcement braided layer with tensile toughening aramid yarn outside the inner sheath with a braiding density of 30% and a braiding pitch ratio of 3; S4: A layer of wear-resistant flexible sheath material is extruded outside the tensile reinforcement braided layer to form an outer sheath with a nominal thickness of 6 mm to obtain a high-voltage flexible cable for a shield machine, such as Figure 1 shown.

[0027] Among them, the preparation of tensile-resistant and toughened aramid yarn is as follows: 5 parts by weight of silica particle grafted aramid yarn, 9 parts by weight of methyl methacrylate and 0.05 parts by weight of azobisisobutyronitrile are added to 400 parts by weight of toluene, the pH is adjusted to 7, and the reaction is stirred in a 60°C oil bath under a nitrogen atmosphere for 6 hours. After the reaction is completed, the temperature is cooled to room temperature. The treated silica particle grafted aramid yarn is filtered, washed with toluene, washed with ethanol and dried in turn to obtain tensile-resistant and toughened aramid yarn.

[0028] The preparation of silica particle grafted aramid fibers is as follows: the aramid fibers are immersed in anhydrous ethanol for ultrasonic cleaning for 30 minutes, and then dried to obtain aramid fibers with surface oil and impurities removed; the aramid fibers with surface oil and impurities removed are placed in a 10% by mass sodium hydroxide solution and immersed at 60° C. for 1 hour; then, the immersed aramid fibers are rinsed with deionized water until neutral, and then dried to obtain pretreated aramid fibers; The pretreated aramid yarn was immersed in a modification solution, which was prepared by a mass ratio of 5:100 of a silane coupling agent KH-550 and a 90% ethanol solution, and ultrasonically dispersed for 30 minutes, and the pH was adjusted to 4. The solution was reacted at 72°C for 1 hour. After the reaction was completed, the aramid yarn was washed with ethanol and dried to obtain a modified aramid yarn. 3 parts by weight of modified aramid fibers were immersed in a reactor filled with 360 parts by weight of anhydrous ethanol, and aqueous ammonia was added to the reactor, the pH was adjusted to 10, and ultrasonic dispersion was performed for 20 minutes. Subsequently, magnetic stirring was performed at 60°C, and 80 parts by weight of reaction liquid was slowly dripped into the reactor during stirring. The reaction liquid was composed of tetraethyl orthosilicate and 70% ethanol solution by volume in a mass ratio of 8:100. After the reaction liquid was added, the reaction was stirred for 4 hours. After the reaction was completed, the modified aramid fibers were washed with ethanol. Finally, the fibers were cured at 105°C for 2 hours to obtain silica particle grafted aramid fibers.

[0029] The flexible and wear-resistant composite filler is prepared by immersing the reed fiber in a sodium hydroxide solution with a mass fraction of 10% for alkalization treatment, and then washing with deionized water and drying to obtain the alkalized reed fiber; Calcium chloride and diammonium hydrogen phosphate were dissolved in deionized water to prepare a calcium chloride solution with a concentration of 0.05 mol / L and a diammonium hydrogen phosphate solution with a concentration of 0.3 mol / L, 3 parts by weight of alkalized reed fiber were added to 500 parts by weight of the calcium chloride solution, and stirred evenly. Then, 60 parts by weight of the diammonium hydrogen phosphate solution were slowly added dropwise under stirring. After the diammonium hydrogen phosphate solution was added dropwise, the pH value of the solution was adjusted to 9 with ammonia water, and stirred in a water bath at 40°C for 3 hours. After the stirring was completed, the solution was aged for 36 hours, and then washed, filtered, dried and crushed to obtain hydroxylated apatite-loaded reed fiber; Hydroxylated apatite-loaded reed fiber was added to an ethanol solution with a volume fraction of 70% to prepare a hydroxylated apatite-loaded reed fiber dispersion solution with a hydroxylated apatite-loaded reed fiber concentration of 3 g / L. Silane coupling agent KH-550 was added to the hydroxylated apatite-loaded reed fiber dispersion solution in an amount of 5% of the mass of the hydroxylated apatite-loaded reed fiber dispersion solution. The reaction was stirred at 50°C for 3 hours. Subsequently, the mixture was filtered and dried to obtain a flexible and wear-resistant composite filler.

[0030] Example 3 A preparation process of a high-voltage flexible cable for a shield machine comprises the following steps: S1: 100 parts by weight of chlorinated polyethylene, 20 parts by weight of silicon dioxide, 5 parts by weight of dibutyl phthalate, 3 parts by weight of antioxidant A, 5 parts by weight of silane coupling agent KH-550 and 3 parts by weight of antioxidant 1010 are uniformly mixed, kneaded, extruded and granulated at an extrusion temperature of 200° C. to obtain an inner sheath material; S2: 100 parts by weight of chlorinated polyethylene, 10 parts by weight of flexible wear-resistant composite filler, 5 parts by weight of dibutyl phthalate, 6 parts by weight of diisopropylbenzene peroxide, 2 parts by weight of antioxidant A, 2 parts by weight of antioxidant H, 7 parts by weight of coupling agent KH-550, 3 parts by weight of antioxidant 1010, and 3 parts by weight of accelerator M are mixed uniformly, kneaded, extruded, and granulated at an extrusion temperature of 200° C. to obtain a wear-resistant flexible sheath material; S3: Extrude a layer of inner sheath material outside the cable core to form an inner sheath with a nominal thickness of 3mm. Then, weave a tensile reinforcement braided layer with tensile toughening aramid yarn outside the inner sheath with a braiding density of 30% and a braiding pitch ratio of 3; S4: A layer of wear-resistant flexible sheath material is extruded outside the tensile reinforcement braided layer to form an outer sheath with a nominal thickness of 6 mm to obtain a high-voltage flexible cable for a shield machine, such as Figure 1 shown.

[0031] Among them, the preparation of tensile-resistant and toughened aramid yarn is as follows: 5 parts by weight of silica particle grafted aramid yarn, 5 parts by weight of methyl methacrylate and 0.05 parts by weight of azobisisobutyronitrile are added to 400 parts by weight of toluene, the pH is adjusted to 5, and the reaction is stirred in a 70°C oil bath under a nitrogen atmosphere for 6 hours. After the reaction is completed, the temperature is cooled to room temperature. The treated silica particle grafted aramid yarn is filtered, washed with toluene, washed with ethanol and dried in turn to obtain tensile-resistant and toughened aramid yarn.

[0032] The preparation of silica particle grafted aramid fibers is as follows: the aramid fibers are immersed in anhydrous ethanol for ultrasonic cleaning for 30 minutes, and then dried to obtain aramid fibers with surface oil and impurities removed; the aramid fibers with surface oil and impurities removed are placed in a 10% by mass sodium hydroxide solution and immersed at 60° C. for 2 hours; then, the immersed aramid fibers are rinsed with deionized water until neutral, and then dried to obtain pretreated aramid fibers; The pretreated aramid yarn was immersed in a modification solution, which was prepared by a mass ratio of 5:100 of a silane coupling agent KH-550 and a 90% ethanol solution, and ultrasonically dispersed for 30 minutes, and the pH was adjusted to 5. The aramid yarn was reacted at 60°C for 2 hours. After the reaction was completed, the aramid yarn was washed with ethanol and dried to obtain a modified aramid yarn. 2 parts by weight of modified aramid yarn were immersed in a reactor filled with 200 parts by weight of anhydrous ethanol, and ammonia water was added to the reactor, the pH was adjusted to 10, and ultrasonic dispersion was performed for 20 minutes. Subsequently, magnetic stirring was performed at 60°C, and 50 parts by weight of reaction liquid was slowly dripped into the reaction solution during the stirring process. The reaction liquid was composed of tetraethyl orthosilicate and 70% ethanol solution by volume in a mass ratio of 10:100. After the reaction liquid was added, the reaction was stirred for 6 hours. After the reaction was completed, the modified aramid yarn was washed with ethanol. Finally, it was cured at 100°C for 2 hours to obtain silica particle grafted aramid yarn.

[0033] The flexible and wear-resistant composite filler is prepared by immersing the reed fiber in a sodium hydroxide solution with a mass fraction of 10% for alkalization treatment, and then washing with deionized water and drying to obtain the alkalized reed fiber; Calcium chloride and diammonium hydrogen phosphate were dissolved in deionized water to prepare a calcium chloride solution with a concentration of 0.05 mol / L and a diammonium hydrogen phosphate solution with a concentration of 0.3 mol / L, 3 parts by weight of alkalized reed fiber were added to 500 parts by weight of the calcium chloride solution, and stirred evenly. Then, 60 parts by weight of the diammonium hydrogen phosphate solution were slowly added dropwise under stirring. After the diammonium hydrogen phosphate solution was added dropwise, the pH value of the solution was adjusted to 10 with ammonia water, and stirred in a water bath at 60° C. for 3 h. After the stirring was completed, the solution was aged for 36 h, and then washed, filtered, dried and crushed to obtain hydroxylated apatite-loaded reed fiber; Hydroxylated apatite-loaded reed fiber was added to an ethanol solution with a volume fraction of 70% to prepare a hydroxylated apatite-loaded reed fiber dispersion solution with a hydroxylated apatite-loaded reed fiber concentration of 3 g / L. Silane coupling agent KH-550 was added to the hydroxylated apatite-loaded reed fiber dispersion solution in an amount of 5% of the mass of the hydroxylated apatite-loaded reed fiber dispersion solution. The reaction was stirred at 70°C for 3 hours, and then, the mixture was filtered and dried to obtain a flexible and wear-resistant composite filler.

[0034] Comparative Example 1 Compared with Example 1, the difference of Comparative Example 1 is that, in the preparation process of the high-voltage flexible cable for the shield machine, the tensile toughened aramid yarn used in step S3 is replaced by the silica particle grafted aramid yarn, and the other steps and components remain unchanged. The cable core is processed and prepared into a high-voltage flexible cable for the shield machine using the cable core exactly the same as that in Example 1, which is recorded as Comparative Example 1.

[0035] Comparative Example 2 Compared with Example 1, the difference of Comparative Example 2 is that, in the preparation process of the high-voltage flexible cable for the shield machine, the tensile toughened aramid yarn used in step S3 is replaced by an aramid yarn that has not been treated in any way, and the other steps and components remain unchanged. The cable core is processed and prepared into a high-voltage flexible cable for the shield machine using the same cable core as that in Example 1, which is recorded as Comparative Example 2.

[0036] Comparative Example 3 Compared with Example 1, the difference of Comparative Example 3 is that, in the preparation process of the high-voltage flexible cable for the shield machine, the flexible and wear-resistant composite filler in step S2 is replaced by hydroxylated apatite-loaded reed fiber, and the other steps and components remain unchanged. The cable core is processed and prepared into a high-voltage flexible cable for the shield machine using the cable core that is exactly the same as that in Example 1, which is recorded as Comparative Example 3.

[0037] Comparative Example 4 Compared with Example 1, the difference of Comparative Example 4 is that, in the preparation process of the high-voltage flexible cable for the shield machine, the flexible and wear-resistant composite filler in step S2 is replaced by reed fiber that has not been treated in any way, and the other steps and components remain unchanged. The cable core is processed and prepared into a high-voltage flexible cable for the shield machine using the same cable core as that in Example 1, which is recorded as Comparative Example 4.

[0038] Comparative Example 5 Compared with Example 1, the difference of Comparative Example 5 is that, in the preparation process of the high-voltage flexible cable for the shield machine, the flexible and wear-resistant composite filler in step S2 is replaced by hydroxylated apatite, and the other steps and components remain unchanged. The cable core is processed and prepared into a high-voltage flexible cable for the shield machine using the cable core exactly the same as that in Example 1, which is recorded as Comparative Example 5.

[0039] Mechanical properties: 3 cables of high-voltage flexible cables for shield machines of Examples 1-3 and Comparative Examples 1-5 were selected as test samples, and the tensile strength and elongation at break were tested according to the standard of GB / T2951-2008. The average values ​​of the tensile strength and elongation at break of each group of test samples were taken as the test results. The results are shown in Table 1.

[0040] Table 1:

[0041] As can be seen from Table 1, the tensile strength and elongation at break test results of the high-voltage flexible cables for shield machines in Examples 1-3 are better than those of the high-voltage flexible cables for shield machines in Comparative Examples 1-5, indicating that the use of tensile-toughened aramid yarns to weave a tensile-reinforced braided layer and the addition of flexible and wear-resistant composite fillers as fillers in the outer sheath can effectively improve the mechanical properties of the high-voltage flexible cables for shield machines, enhance the tensile strength of the high-voltage flexible cables for shield machines, and effectively withstand the tensile force to which the high-voltage flexible cables for shield machines are subjected during use.

[0042] Bending resistance: In the high-voltage flexible cables for shield machines of Examples 1-3 and Comparative Examples 1-5, 3 cables were selected as test samples, and the test samples were subjected to bending tests using a bending machine. The number of bending and breaking of each group of test samples was recorded, and the average number of bending and breaking of each group of test samples was taken as the test result. The results are shown in Table 2.

[0043] Table 2:

[0044] As can be seen from Table 2, the bending and fracture test results of the high-voltage flexible cables for shield machines in Examples 1-3 are better than those of the high-voltage flexible cables for shield machines in Comparative Examples 1-5, indicating that the use of tensile-resistant and toughened aramid yarns to weave a tensile-resistant reinforced braided layer and the addition of flexible and wear-resistant composite fillers as fillers in the outer sheath can effectively improve the flexibility and bending resistance of the high-voltage flexible cables for shield machines, improve the bending resistance of the high-voltage flexible cables for shield machines, and adapt to frequent bending.

[0045] Wear resistance: 3 cables were selected as test samples from each of the high-voltage flexible cables for shield machines in Examples 1-3 and Comparative Examples 3-5. Friction and wear tests were performed on the test samples in accordance with the standard of GB / T3960-2016. The loss of each test sample in each group of examples and comparative examples was counted, and the average wear rate of each group of test samples was calculated as the test result. Wear rate (%) = loss / cable mass before wear*100%. The results are shown in Table 3.

[0046] Table 3:

[0047] As can be seen from Table 3, the wear rate results of the high-voltage flexible cables for shield machines in Examples 1-3 are all less than 1.5% after the friction and wear test, and the friction loss is lighter than that of the high-voltage flexible cables for shield machines in Comparative Examples 3-5, indicating that the wear resistance of the high-voltage flexible cables for shield machines can be effectively improved by adding flexible and wear-resistant composite fillers as fillers in the outer sheath, among which the hydroxylated apatite in the flexible and wear-resistant composite fillers mainly plays a wear-resistant effect.

[0048] Flame retardant properties: The wear-resistant flexible sheath materials used in Examples 1-3 and Comparative Examples 3-5 were tested according to the standard of GB / T2406.1-2008. Each group was tested 3 times, and the test average values ​​of the samples of each group of Examples and Comparative Examples were calculated as the test results. The results are shown in Table 4.

[0049] Table 4:

[0050] As can be seen from Table 4, the flame retardant properties of the high-voltage flexible cables for shield machines in Examples 1-3 are better than those of the high-voltage flexible cables for shield machines in Comparative Examples 3-5, indicating that the flame retardant properties of the high-voltage flexible cables for shield machines can be effectively improved by adding flexible and wear-resistant composite fillers as fillers in the outer sheath, wherein the hydroxylated apatite in the flexible and wear-resistant composite fillers mainly plays a flame retardant effect.

[0051] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all such improvements and changes should fall within the scope of protection of the appended claims of the present invention. Parts not described in detail in this specification belong to the prior art known to those skilled in the art.

Claims

1. A high-voltage flexible cable for a shield machine, comprising a cable core, an inner sheath, a tensile reinforcement braided layer and an outer sheath arranged in sequence from the inside to the outside, the cable core is composed of three main cores and three ground cores, the centers of the three main cores are arranged in an equilateral triangle, and the three ground cores are respectively arranged in the gap between every two adjacent main cores; It is characterized in that The raw material of the tensile reinforcement braided layer is tensile toughened aramid yarn, and the raw material of the outer sheath is wear-resistant flexible sheath material; The tensile toughened aramid yarn is prepared by using silica particle grafted aramid yarn and methyl methacrylate as raw materials, using azobisisobutyronitrile as an initiator, and grafting polymethyl methacrylate on the surface of the silica particle grafted aramid yarn; The silica particle grafted aramid fiber is obtained by loading silica particles on the surface of the modified aramid fiber after the aramid fiber is modified by a silane coupling agent. The raw materials of the wear-resistant flexible sheath material are 80 to 120 parts by weight of rubber base material, 10 to 30 parts by weight of flexible wear-resistant composite filler, 1 to 5 parts by weight of plasticizer, 2 to 6 parts by weight of vulcanizer, 2 to 5 parts by weight of antioxidant, 1 to 7 parts by weight of coupling agent KH-550, 1 to 3 parts by weight of antioxidant and 1 to 3 parts by weight of accelerator; The flexible and wear-resistant composite filler is obtained by hydrophobically modifying hydroxyapatite-loaded reed fiber with a silane coupling agent KH-550. The hydroxyapatite-loaded reed fiber is obtained by forming hydroxyapatite crystals on the surface of the reed fiber using soluble calcium salt and soluble phosphate as raw materials.

2. The high-voltage flexible cable for a shield machine according to claim 1, characterized in that: The raw material of the inner protective layer is the inner sheath material, and the inner sheath material includes a rubber base material, silicon dioxide, a vulcanizing agent, an antioxidant, a silane coupling agent KH-550 and an antioxidant.

3. The high-voltage flexible cable for a shield machine according to claim 1 or 2, characterized in that: The rubber substrate is at least one of chloroprene rubber, styrene-butadiene rubber or chlorinated polyethylene.

4. The high-voltage flexible cable for a shield machine according to claim 1, characterized in that: The preparation of silica particle grafted aramid fiber specifically comprises the following steps: The aramid yarn is soaked in anhydrous ethanol and ultrasonically cleaned for 20 to 30 minutes, and then dried to obtain the aramid yarn with surface oil and impurities removed. The aramid yarn with surface oil and impurities removed is placed in a sodium hydroxide solution with a mass fraction of 5 to 10%, and soaked at 60 to 70° C. for 1 to 2 hours. Subsequently, the soaked aramid yarn is rinsed with deionized water until it is neutral, and dried to obtain the pretreated aramid yarn. The pretreated aramid yarn is immersed in the modified solution, ultrasonically dispersed for 10 to 30 minutes, the pH is adjusted to 4 to 5, and reacted at 56 to 72° C. for 1 to 2 hours. After the reaction is completed, the aramid yarn after the reaction is washed with ethanol and dried to obtain the modified aramid yarn; 1 to 3 parts by weight of modified aramid yarns are immersed in a reactor filled with 150 to 360 parts by weight of anhydrous ethanol, and aqueous ammonia is added to the reactor, and the pH is adjusted to 9 to 10, and ultrasonic dispersion is performed for 10 to 20 minutes. Subsequently, magnetic stirring is performed at 50 to 60°C, and 50 to 80 parts by weight of reaction liquid are slowly dripped into the reaction solution during the stirring process. After the reaction solution is dripped, the reaction is continued by stirring for 4 to 6 hours. After the reaction is completed, the modified aramid yarns are washed with ethanol, and finally, the aramid yarns are cured at 90 to 105°C for 1 to 2 hours to obtain silica particle grafted aramid yarns.

5. The high-voltage flexible cable for a shield machine according to claim 4, characterized in that: The modified solution is prepared by mixing silane coupling agent KH-550 and ethanol solution with a volume fraction of 90% in a mass ratio of (2-5):

100.

6. The high-voltage flexible cable for a shield machine according to claim 5, characterized in that: The reaction solution is prepared by mixing ethyl orthosilicate and 70% ethanol solution by volume in a mass ratio of (5-10):

100.

7. The high-voltage flexible cable for a shield machine according to claim 1, characterized in that: The preparation of tensile toughened aramid yarn specifically comprises the following steps: 1-5 parts by weight of silica particle grafted aramid yarn, 4-9 parts by weight of methyl methacrylate and 0.02-0.05 parts by weight of azobisisobutyronitrile are added to 200-400 parts by weight of toluene, and the pH is adjusted to 5-7. Under a nitrogen atmosphere, the mixture is stirred in an oil bath at 60-80°C for 3-6 hours. After the reaction, the mixture is cooled to room temperature. The treated silica particle grafted aramid yarn is filtered, washed with toluene, washed with ethanol and dried to obtain a tensile toughened aramid yarn.

8. The high-voltage flexible cable for a shield machine according to claim 1, characterized in that: The preparation of the flexible and wear-resistant composite filler specifically includes the following steps: The reed fiber is immersed in a sodium hydroxide solution with a mass fraction of 5 to 10% for alkalization treatment, and then washed with deionized water and dried to obtain the alkalized reed fiber; Dissolve a soluble calcium salt and a soluble phosphate in deionized water to prepare a calcium salt solution with a concentration of 0.05-0.1 mol / L and a phosphate solution with a concentration of 0.3-1 mol / L, add 1-3 parts by weight of alkalized reed fiber to 200-600 parts by weight of the calcium salt solution, stir evenly, slowly drop 20-60 parts by weight of the phosphate solution under stirring, adjust the pH of the solution to 8-10 with ammonia water after the phosphate solution is added, stir in a water bath at 30-75° C. for 1-3 hours, age for 24-36 hours after the stirring is completed, and then wash, filter, dry and crush to obtain hydroxylated apatite-loaded reed fiber; Hydroxylated apatite-loaded reed fiber is added to an ethanol solution with a volume fraction of 70% to prepare a hydroxylated apatite-loaded reed fiber dispersion solution with a hydroxylated apatite-loaded reed fiber concentration of 1 to 3 g / L. Silane coupling agent KH-550 is added to the hydroxylated apatite-loaded reed fiber dispersion solution in an amount of 3 to 5% of the mass of the hydroxylated apatite-loaded reed fiber dispersion solution. The mixture is stirred and reacted at 40 to 70° C. for 1 to 3 hours. Subsequently, the mixture is filtered and dried to obtain a flexible and wear-resistant composite filler.

9. The high-voltage flexible cable for a shield machine according to claim 2, characterized in that: The plasticizer is at least one of dioctyl phthalate, dibutyl phthalate, and diisononyl phthalate; the vulcanizer is at least one of tert-butyl perbenzoate, diisopropylbenzene peroxide, and tert-butylisopropylbenzene peroxide; the antioxidant is at least one of antioxidant A, antioxidant H, antioxidant ODA, or antioxidant 4020; the antioxidant is at least one of antioxidant TPP, antioxidant 1010, antioxidant 1076, or antioxidant 168; and the accelerator is at least one of accelerator D, accelerator M, or accelerator PZ.

10. A process for preparing a high voltage flexible cable for a shield machine according to claim 2, characterized in that: The steps include: S1: uniformly mixing the raw materials of the inner sheath material, kneading, extruding and granulating to obtain the inner sheath material; S2: uniformly mixing the raw materials of the wear-resistant flexible sheath material, kneading, extruding and granulating to obtain the wear-resistant flexible sheath material; S3: Extrude a layer of inner sheath material outside the cable core to form an inner sheath, and then weave a layer of tensile reinforcement braided layer with tensile toughening aramid yarn outside the inner sheath, with a braiding density of 20-35% and a braiding section diameter ratio of 2-4.5; S4: A layer of wear-resistant flexible sheath material is extruded outside the tensile reinforcement braided layer to form an outer sheath to obtain a high-voltage flexible cable for a shield machine.

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