A strong radiation resistant nuclear power plant pile top cable and its preparation method

Abstract

The present invention relates to the field of cable technology, specifically to a strong radiation resistant nuclear power plant top cable and a preparation method thereof. The present invention mixes EPDM rubber, ethylene-vinyl acetate copolymer, chlorinated polyethylene, modified carbon black, white carbon black, paraffin, radiation resistant additive, stearic acid, zinc oxide, montmorillonite, antioxidant and ultraviolet absorber, and removes the rubber to obtain a rubber compound; the rubber compound is uniformly mixed with a cross-linking sensitizer, sulfur and an accelerator, and is open-mixed to obtain a rubber compound; the rubber compound is irradiated and vulcanized to obtain a protective sheath material; the protective sheath material is extruded on the outside of an insulating layer to form a sheath layer to obtain a strong radiation resistant nuclear power plant top cable, which has stable and efficient radiation resistance, aging resistance, wear resistance, tensile tear resistance and flame retardant properties, and fully meets the use requirements of the nuclear power plant top cable.

Description

Technical Field

[0001] The invention relates to the technical field of cables, in particular to a strong radiation resistant nuclear power plant pile top cable and a preparation method thereof. Background Art

[0002] During the operation of a nuclear power plant, the top cable is subjected to a high-intensity radiation environment, which requires it to have good radiation resistance. Conventional cables are prone to aging, performance degradation, and even short circuits and other safety hazards in a radiation environment. Therefore, the development of a strong radiation-resistant cable material is crucial to ensure the safety and stable operation of nuclear power plants.

[0003] With the continuous advancement of nuclear power technology and the improvement of radiation protection standards, the radiation resistance of existing cable materials can no longer meet the needs of high-intensity radiation environments. The molecular chains of traditional polymer insulation materials (such as polyethylene, polyvinyl chloride, etc.) are prone to breakage in strong radiation environments, resulting in significant degradation of insulation performance, which affects the safety and reliability of cables. In order to improve the radiation resistance of polymer materials, some additives are usually added, but many existing additives have poor compatibility with the matrix material, resulting in uneven dispersion of the additives in the composite material and unable to fully exert their effects. This not only affects the comprehensive performance of the composite material, but may also shorten the service life of the material.

[0004] Therefore, we propose a strong radiation resistant nuclear power plant pile top cable and a preparation method thereof. Summary of the invention

[0005] The object of the present invention is to provide a strong radiation resistant nuclear power plant pile top cable and a preparation method thereof, so as to solve the problems raised in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a strong radiation resistant nuclear power plant pile top cable comprises the following steps:

[0008] Step S1: Wrap the shielding tape around the wire core to form a shielding layer;

[0009] Step S2: Extruding an insulating material onto the outer side of the shielding layer to form an insulating layer;

[0010] Step S3: adding EPDM rubber, ethylene-vinyl acetate copolymer and chlorinated polyethylene into an internal mixer, mixing at 95-105° C. for 2-3 min, adding modified carbon black, white carbon black, paraffin, radiation-resistant additive, stearic acid, zinc oxide, montmorillonite, antioxidant and ultraviolet absorber, mixing at 145-155° C. for 10-15 min, draining the rubber to obtain a rubber compound; uniformly mixing the rubber compound with a cross-linking sensitizer, sulfur and an accelerator, and performing open mixing to obtain a rubber compound; irradiating and vulcanizing the rubber compound to obtain a protective sheath material; extruding the protective sheath material onto the outside of the insulating layer to form a sheath layer to obtain a nuclear power plant top cable resistant to strong radiation.

[0011] Furthermore, the wire core is formed by twisting 2 to 10 tinned copper wire conductors.

[0012] Furthermore, the insulating material is radiation cross-linked polyethylene.

[0013] Furthermore, the protective cover material includes the following components by weight: 70-80 parts of EPDM rubber, 10-20 parts of ethylene-vinyl acetate copolymer, 15-25 parts of chlorinated polyethylene, 20-30 parts of modified carbon black, 10-20 parts of white carbon black, 4-8 parts of cross-linking sensitizer, 2-4 parts of sulfur, 1-3 parts of paraffin, 4-12 parts of radiation-resistant additive, 1-3 parts of stearic acid, 3-5 parts of zinc oxide, 2-4 parts of montmorillonite, 2-4 parts of antioxidant, 1-2 parts of accelerator, and 0.2-0.5 parts of ultraviolet absorber.

[0014] Further, the preparation method of the modified carbon black is as follows:

[0015] Under nitrogen protection, the macromolecular coupling agent and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide are mixed evenly, the temperature is raised to 120-130°C, triphenylphosphine is added, the reaction is carried out for 6-8h, the temperature is lowered to 40-50°C, 4-hydroxyphenylboric acid is added, the reaction is continued for 2-4h, and the flame retardant is obtained after filtering, washing and drying; carbon black, anhydrous ethanol, deionized water and flame retardant are mixed evenly, acetic acid is added to adjust the pH value to 3.5-4.0, the reaction is carried out at 50-70°C for 8-10h, and the modified carbon black is obtained after filtering, washing and drying.

[0016] Furthermore, the mass ratio of the macromolecular coupling agent, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and triphenylphosphine is 1:(1-2):(0.08-0.12).

[0017] Furthermore, the mass of the 4-hydroxyphenylboronic acid is 15-20% of the mass of the macromolecular coupling agent.

[0018] Furthermore, the mass ratio of the carbon black to anhydrous ethanol, deionized water and flame retardant is 1:(15-20):(3-5):(0.5-1.0).

[0019] Furthermore, the preparation method of the macromolecular coupling agent is as follows:

[0020] Under nitrogen protection, EPDM rubber and toluene are mixed evenly, glycidyl methacrylate and γ-methacryloxypropyltrimethoxysilane are added, the temperature is raised to 80-90°C, a mixed solution of benzoyl peroxide and toluene is added dropwise, the dripping is completed in 30-50 minutes, the reaction is carried out for 8-12 hours, and a macromolecular coupling agent is obtained after precipitation and drying.

[0021] Furthermore, the mass ratio of the EPDM rubber, toluene, glycidyl methacrylate and γ-methacryloxypropyltrimethoxysilane is 1:(8-10):(0.5-0.8):(0.2-0.4).

[0022] Furthermore, the mass ratio of the benzoyl peroxide to toluene is 1:(3-5), and the mass of the benzoyl peroxide is 1-3% of the total mass of the EPDM rubber, glycidyl methacrylate and γ-methacryloxypropyltrimethoxysilane.

[0023] Furthermore, the preparation method of the radiation-resistant additive is as follows:

[0024] Step (1): evenly mix boron nitride and sodium hydroxide solution, stir at 70-80° C. for 10-12 hours, heat to 110-120° C. for reaction for 10-12 hours, cool to room temperature, filter, wash, and dry to obtain hydroxylated boron nitride; evenly mix hydroxylated boron nitride, anhydrous ethanol, deionized water, and a macromolecular coupling agent, add acetic acid to adjust the pH value to 3.5-4.0, react at 50-70° C. for 6-8 hours, filter, wash, and dry to obtain modified boron nitride;

[0025] Step (2): under nitrogen protection, dispersing lithium chloride in N-methyl-2-pyrrolidone, adding sodium hydroxide, p-dichlorobenzene, 2,5-dichlorobenzoic acid and anhydrous sodium sulfide, mixing evenly, heating to 220-230° C., reacting for 5-7 hours, washing and drying to obtain carboxylated polyphenylene sulfide;

[0026] Step (3): mix carboxylated polyphenylene sulfide and N,N-dimethylformamide evenly, add modified boron nitride and tetrabutylammonium bromide, react at 70-80°C for 4-6h, cool to 45-55°C, add sodium hydroxide, continue to react for 2-3h, wash and distill under reduced pressure to obtain a radiation-resistant additive.

[0027] In the above technical scheme, boron nitride (BN) has excellent radiation stability, but its poor compatibility with the polymer matrix limits its performance. The surface of boron nitride is modified by a macromolecular coupling agent to obtain modified boron nitride, which improves the dispersibility of boron nitride in EPDM rubber composite materials and enhances compatibility. At the same time, polyphenylene sulfide has the characteristics of high temperature resistance, radiation resistance, corrosion resistance, wear resistance, flame retardancy, good molding and processing performance, etc. The epoxy groups on the surface of modified boron nitride are used to undergo a ring-opening reaction with the carboxyl groups in carboxylated polyphenylene sulfide to further enhance the radiation resistance of the material and obtain a radiation-resistant additive.

[0028] Furthermore, in the step (1), the mass ratio of boron nitride to sodium hydroxide solution is 1:(4-5), and the concentration of the sodium hydroxide solution is 2-5 mol / L.

[0029] Furthermore, in the step (1), the mass ratio of hydroxylated boron nitride to anhydrous ethanol, deionized water, and macromolecular coupling agent is 1:(15-20):(2-4):(0.4-0.8).

[0030] Furthermore, in step (2), the mass ratio of lithium chloride, N-methyl-2-pyrrolidone, sodium hydroxide, p-dichlorobenzene, 2,5-dichlorobenzoic acid and anhydrous sodium sulfide is 1: (25-30): (0.25-0.30): (11-12): (1.1-1.2): (0.7-0.8).

[0031] Furthermore, in the step (3), the mass ratio of carboxylated polyphenylene sulfide, N,N-dimethylformamide and modified boron nitride is 1:(6-8):(2-4).

[0032] Furthermore, in step (3), the mass ratio of modified boron nitride, tetrabutylammonium bromide and sodium hydroxide is 1:(0.1-0.3):(1-2).

[0033] Furthermore, the cross-linking sensitizer is one of triallyl cyanurate and triallyl isocyanurate.

[0034] Furthermore, the antioxidant is prepared by compounding antioxidant 4010NA and antioxidant 2246 in a mass ratio of 1:1.

[0035] Furthermore, the accelerator is accelerator CZ.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. A strong radiation resistant nuclear power plant top cable and a preparation method thereof of the present invention adopts a free radical polymerization method to graft glycidyl methacrylate and γ-methacryloxypropyltrimethoxysilane on a flexible ethylene propylene rubber chain to obtain a macromolecular coupling agent containing an epoxy group; compared with traditional small molecule coupling agents, the modification effect is not obvious enough due to the weak interaction between the coupling agent and the polymer matrix, while the macromolecular coupling agent prepared by the present invention can not only form a strong physical entanglement with the polymer matrix molecular chain, but also optimize and control the interface structure of the composite material by adjusting its molecular structure and molecular weight;

[0038] Under the action of triphenylphosphine catalyst, the epoxy group in the macromolecular coupling agent reacts with the PH bond in 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and then 4-hydroxyphenylboric acid is added to participate in the reaction to obtain a flame retardant containing silaneoxy groups. The flame retardant is grafted on the surface of carbon black by reacting with the silaneoxy groups. This not only gives the base rubber environmentally friendly and efficient flame retardant properties, but also improves the interfacial compatibility between carbon black and the base rubber, reduces the agglomeration of carbon black, and significantly improves the wear resistance, aging resistance and mechanical strength of the base rubber.

[0039] 2. A strong radiation resistant nuclear power plant top cable and its preparation method of the present invention, the surface of boron nitride is modified by a macromolecular coupling agent to obtain modified boron nitride, which significantly improves its dispersibility in EPDM rubber composite materials and enhances compatibility; at the same time, polyphenylene sulfide has the characteristics of high temperature resistance, radiation resistance, corrosion resistance, wear resistance, flame retardancy, good molding and processing performance, etc., and the epoxy group on the surface of the modified boron nitride is used to react with the carboxyl group in the carboxylated polyphenylene sulfide to undergo a ring-opening reaction, thereby achieving an effective combination of polyphenylene sulfide and boron nitride, further enhancing the radiation resistance of the material, and obtaining a radiation resistant additive. Therefore, the cable prepared by the present invention has stable and efficient radiation resistance, aging resistance, wear resistance, tensile tear resistance and a certain degree of flame retardancy, which fully meets the use requirements of nuclear power plant top cables. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0041] In this embodiment, the shielding tape is made of copper tape, material T2, from Shanghai Xingnuo Industrial Co., Ltd.; irradiated cross-linked polyethylene:

[0042] Product No. PX4855, from Dongguan Haopinfa Plastic Raw Materials Co., Ltd.; EPDM rubber: brand name is Sinopec Mitsui EPDM 3092PM; ethylene-vinyl acetate copolymer: DuPont of the United States, brand name is 40L-03; chlorinated polyethylene: brand name is 135, from Shijiazhuang Tengchi Chemical Co., Ltd.; carbon black: brand name is Cabot N330; white carbon black: Wacker V15 of Germany; zinc oxide: product No. 01, from Henan Shengkun Chemical Products Co., Ltd.; montmorillonite: product No. mtt-200-2500, from Lingshou County Tuolin Mineral Products Processing Plant; ultraviolet absorber: model name is UV-329; cross-linking sensitizer: triallyl isocyanurate, CAS No. is 1025-15-6; tinned copper wire conductor: diameter 0.5mm.

[0043] In the following examples and comparative examples, 1 part is equal to 10 g.

[0044] Embodiment 1: A method for preparing a strong radiation resistant nuclear power plant top cable, comprising the following processes:

[0045] Step S1: Wrap a shielding tape around a wire core (the wire core is formed by twisting 5 tinned copper wire conductors) to form a shielding layer;

[0046] Step S2: Extruding the irradiated cross-linked polyethylene on the outer side of the shielding layer to form an insulating layer;

[0047] Step S3: adding 70 parts of EPDM rubber, 10 parts of ethylene-vinyl acetate copolymer and 15 parts of chlorinated polyethylene into an internal mixer, mixing at 95° C. for 2 min, adding 20 parts of modified carbon black, 10 parts of white carbon black, 1 part of paraffin wax, 4 parts of radiation-resistant additives, 1 part of stearic acid, 3 parts of zinc oxide, 2 parts of montmorillonite, 2 parts of antioxidants and 0.2 parts of ultraviolet absorbers, mixing at 145° C. for 10 min, draining the rubber to obtain a rubber compound; mixing the rubber compound and 4 parts of a cross-linking sensitizer, 2 parts of sulfur and 1 part of an accelerator CZ evenly, and performing open mixing to obtain a rubber compound; performing radiation vulcanization on the rubber compound to obtain a protective sheath material; extruding the protective sheath material on the outside of the insulating layer to form a sheath layer to obtain a strong radiation-resistant nuclear power plant top cable;

[0048] The preparation method of modified carbon black is as follows:

[0049] Under nitrogen protection, 10 parts of macromolecular coupling agent and 10 parts of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were mixed evenly, heated to 120°C, 0.8 parts of triphenylphosphine were added, reacted for 6 hours, cooled to 40°C, 1.5 parts of 4-hydroxyphenylboric acid were added, and the reaction was continued for 2 hours. After filtering, washing and drying, a flame retardant was obtained; 20 parts of carbon black, 300 parts of anhydrous ethanol, 60 parts of deionized water and 10 parts of flame retardant were mixed evenly, acetic acid was added to adjust the pH value to 3.5, reacted at 50°C for 8 hours, filtered, washed and dried, and modified carbon black was obtained;

[0050] The preparation method of the macromolecular coupling agent is as follows:

[0051] Under nitrogen protection, 12 parts of EPDM rubber and 96 parts of toluene were mixed evenly, 6 parts of glycidyl methacrylate and 2.4 parts of γ-methacryloxypropyltrimethoxysilane were added, the temperature was raised to 80°C, and a mixed solution of 0.2 parts of benzoyl peroxide and 0.6 parts of toluene was added dropwise, and the mixture was added over 30 minutes. The mixture was reacted for 8 hours, and a macromolecular coupling agent was obtained after precipitation and drying.

[0052] The preparation method of the radiation-resistant additive is as follows:

[0053] Step (1): 4 parts of boron nitride and 16 parts of 2 mol / L sodium hydroxide solution are mixed uniformly, stirred at 70°C for 10 hours, heated to 110°C for reaction for 10 hours, cooled to room temperature, filtered, washed, and dried to obtain hydroxylated boron nitride; 4 parts of hydroxylated boron nitride and 60 parts of anhydrous ethanol, 8 parts of deionized water, and 1.6 parts of a macromolecular coupling agent are mixed uniformly, acetic acid is added to adjust the pH value to 3.5, reacted at 50°C for 6 hours, filtered, washed, and dried to obtain modified boron nitride;

[0054] Step (2): under nitrogen protection, 2 parts of lithium chloride are dispersed in 50 parts of N-methyl-2-pyrrolidone, 0.5 parts of sodium hydroxide, 22 parts of p-dichlorobenzene, 2.2 parts of 2,5-dichlorobenzoic acid and 1.4 parts of anhydrous sodium sulfide are added and mixed evenly, the mixture is heated to 220° C., reacted for 5 hours, and after washing and drying, carboxylated polyphenylene sulfide is obtained;

[0055] Step (3): Mix 2 parts of carboxylated polyphenylene sulfide and 12 parts of N,N-dimethylformamide evenly, add 4 parts of modified boron nitride and 0.4 parts of tetrabutylammonium bromide, react at 70°C for 4 hours, cool to 45°C, add 4 parts of sodium hydroxide, continue to react for 2 hours, wash and distill under reduced pressure to obtain a radiation-resistant additive.

[0056] Embodiment 2: A method for preparing a strong radiation resistant nuclear power plant pile top cable, comprising the following processes:

[0057] Step S1: Wrap a shielding tape around a wire core (the wire core is formed by twisting 5 tinned copper wire conductors) to form a shielding layer;

[0058] Step S2: Extruding the irradiated cross-linked polyethylene on the outer side of the shielding layer to form an insulating layer;

[0059] Step S3: adding 75 parts of EPDM rubber, 15 parts of ethylene-vinyl acetate copolymer and 20 parts of chlorinated polyethylene into an internal mixer, mixing at 100° C. for 2.5 min, adding 25 parts of modified carbon black, 15 parts of white carbon black, 2 parts of paraffin wax, 8 parts of radiation-resistant additives, 2 parts of stearic acid, 4 parts of zinc oxide, 3 parts of montmorillonite, 3 parts of antioxidants and 0.3 parts of ultraviolet absorbers, mixing at 150° C. for 12 min, draining the rubber, and obtaining a rubber compound; uniformly mixing the rubber compound with 6 parts of a cross-linking sensitizer, 3 parts of sulfur and 1.5 parts of an accelerator CZ, and performing open mixing to obtain a rubber compound; irradiating and vulcanizing the rubber compound to obtain a protective sheath material; extruding the protective sheath material on the outside of the insulating layer to form a sheath layer, and obtaining a strong radiation-resistant nuclear power plant top cable;

[0060] The preparation method of modified carbon black is as follows:

[0061] Under nitrogen protection, 12 parts of macromolecular coupling agent and 18 parts of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were mixed evenly, heated to 125°C, 1.2 parts of triphenylphosphine were added, reacted for 7 hours, cooled to 45°C, 2.16 parts of 4-hydroxyphenylboric acid were added, and the reaction was continued for 3 hours. After filtering, washing and drying, a flame retardant was obtained; 25 parts of carbon black and 450 parts of anhydrous ethanol, 100 parts of deionized water and 20 parts of flame retardant were mixed evenly, acetic acid was added to adjust the pH value to 3.8, reacted at 60°C for 9 hours, filtered, washed and dried, and modified carbon black was obtained;

[0062] The preparation method of the macromolecular coupling agent is as follows:

[0063] Under nitrogen protection, 16 parts of EPDM rubber and 144 parts of toluene were mixed evenly, 9.6 parts of glycidyl methacrylate and 4.8 parts of γ-methacryloxypropyltrimethoxysilane were added, the temperature was raised to 85°C, and a mixed solution of 0.6 parts of benzoyl peroxide and 2.4 parts of toluene was added dropwise, and the mixture was added over 40 minutes. The mixture was reacted for 10 hours, and a macromolecular coupling agent was obtained after precipitation and drying.

[0064] The preparation method of the radiation-resistant additive is as follows:

[0065] Step (1): 6 parts of boron nitride and 27 parts of 4 mol / L sodium hydroxide solution are mixed uniformly, stirred at 75°C for 11 hours, heated to 115°C for reaction for 11 hours, cooled to room temperature, filtered, washed, and dried to obtain hydroxylated boron nitride; 6 parts of hydroxylated boron nitride and 108 parts of anhydrous ethanol, 18 parts of deionized water, and 3.6 parts of a macromolecular coupling agent are mixed uniformly, acetic acid is added to adjust the pH value to 4.0, reacted at 60°C for 7 hours, filtered, washed, and dried to obtain modified boron nitride;

[0066] Step (2): under nitrogen protection, 2 parts of lithium chloride are dispersed in 56 parts of N-methyl-2-pyrrolidone, 0.56 parts of sodium hydroxide, 23 parts of p-dichlorobenzene, 2.3 parts of 2,5-dichlorobenzoic acid and 1.5 parts of anhydrous sodium sulfide are added and mixed evenly, the mixture is heated to 230° C., reacted for 7 hours, and washed and dried to obtain carboxylated polyphenylene sulfide;

[0067] Step (3): 2 parts of carboxylated polyphenylene sulfide and 14 parts of N,N-dimethylformamide are mixed evenly, 6 parts of modified boron nitride and 0.4 parts of tetrabutylammonium bromide are added, and the mixture is reacted at 80°C for 6 hours, cooled to 55°C, 3 parts of sodium hydroxide are added, and the reaction is continued for 3 hours. After washing and vacuum distillation, a radiation-resistant additive is obtained.

[0068] Embodiment 3: A method for preparing a strong radiation resistant nuclear power plant top cable, comprising the following processes:

[0069] Step S1: Wrap a shielding tape around a wire core (the wire core is formed by twisting 5 tinned copper wire conductors) to form a shielding layer;

[0070] Step S2: Extruding the irradiated cross-linked polyethylene on the outer side of the shielding layer to form an insulating layer;

[0071] Step S3: adding 80 parts of EPDM rubber, 20 parts of ethylene-vinyl acetate copolymer and 25 parts of chlorinated polyethylene into an internal mixer, mixing at 105° C. for 3 min, adding 30 parts of modified carbon black, 20 parts of white carbon black, 3 parts of paraffin wax, 12 parts of radiation-resistant additives, 3 parts of stearic acid, 5 parts of zinc oxide, 4 parts of montmorillonite, 4 parts of antioxidants and 0.5 parts of ultraviolet absorbers, mixing at 155° C. for 15 min, draining the rubber to obtain a rubber compound; mixing the rubber compound and 8 parts of a cross-linking sensitizer, 4 parts of sulfur and 2 parts of an accelerator CZ evenly, and performing open mixing to obtain a rubber compound; performing radiation vulcanization on the rubber compound to obtain a protective sheath material; extruding the protective sheath material on the outside of the insulating layer to form a sheath layer to obtain a strong radiation-resistant nuclear power plant top cable;

[0072] The preparation method of modified carbon black is as follows:

[0073] Under nitrogen protection, 15 parts of macromolecular coupling agent and 30 parts of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were mixed evenly, heated to 130°C, 0.15 parts of triphenylphosphine were added, reacted for 8 hours, cooled to 50°C, 2.7 parts of 4-hydroxyphenylboric acid were added, and the reaction was continued for 4 hours. After filtering, washing and drying, a flame retardant was obtained; 30 parts of carbon black, 600 parts of anhydrous ethanol, 150 parts of deionized water and 30 parts of flame retardant were mixed evenly, acetic acid was added to adjust the pH value to 4.0, reacted at 70°C for 10 hours, filtered, washed and dried, and modified carbon black was obtained;

[0074] The preparation method of the macromolecular coupling agent is as follows:

[0075] Under nitrogen protection, 25 parts of ethylene propylene diene monomer rubber and 250 parts of toluene were mixed evenly, 20 parts of glycidyl methacrylate and 10 parts of γ-methacryloxypropyl trimethoxysilane were added, the temperature was raised to 90°C, and a mixed solution of 1.65 parts of benzoyl peroxide and 8.25 parts of toluene was added dropwise, and the mixture was added over 50 minutes. The mixture was reacted for 12 hours, and a macromolecular coupling agent was obtained after precipitation and drying.

[0076] The preparation method of the radiation-resistant additive is as follows:

[0077] Step (1): 12 parts of boron nitride and 60 parts of 5 mol / L sodium hydroxide solution are mixed uniformly, stirred at 80°C for 12 hours, heated to 120°C for reaction for 12 hours, cooled to room temperature, filtered, washed, and dried to obtain hydroxylated boron nitride; 12 parts of hydroxylated boron nitride and 240 parts of anhydrous ethanol, 48 parts of deionized water, and 9.6 parts of a macromolecular coupling agent are mixed uniformly, acetic acid is added to adjust the pH value to 4.0, reacted at 70°C for 8 hours, filtered, washed, and dried to obtain modified boron nitride;

[0078] Step (2): under nitrogen protection, 3 parts of lithium chloride are dispersed in 90 parts of N-methyl-2-pyrrolidone, 0.9 parts of sodium hydroxide, 36 parts of p-dichlorobenzene, 3.6 parts of 2,5-dichlorobenzoic acid and 2.4 parts of anhydrous sodium sulfide are added and mixed evenly, the mixture is heated to 230° C., reacted for 7 hours, and washed and dried to obtain carboxylated polyphenylene sulfide;

[0079] Step (3): Mix 3 parts of carboxylated polyphenylene sulfide and 24 parts of N,N-dimethylformamide evenly, add 12 parts of modified boron nitride and 3.6 parts of tetrabutylammonium bromide, react at 80°C for 6 hours, cool to 55°C, add 24 parts of sodium hydroxide, continue to react for 3 hours, wash and distill under reduced pressure to obtain a radiation-resistant additive.

[0080] Comparative Example 1: A method for preparing a strong radiation resistant nuclear power plant top cable, comprising the following processes:

[0081] Compared with Example 2, the modified carbon black in Comparative Example 1 is replaced with carbon black of the same mass, and the other steps are the same as those in Example 2.

[0082] Comparative Example 2: A method for preparing a strong radiation resistant nuclear power plant top cable, comprising the following processes:

[0083] Compared with Example 2, in Comparative Example 2, the macromolecular coupling agent is replaced with 3-glycidyloxypropyltrimethoxysilane of the same mass, and the other steps are the same as those of Example 2.

[0084] Comparative Example 3: A method for preparing a strong radiation resistant nuclear power plant top cable, comprising the following processes:

[0085] Compared with Example 2, in Comparative Example 3, the radiation-resistant additive is replaced with boron nitride of the same mass, and the other steps are the same as those of Example 2.

[0086] Comparative Example 4: A method for preparing a strong radiation resistant nuclear power plant top cable, comprising the following processes:

[0087] The preparation method of the radiation-resistant additive is as follows:

[0088] Step (1): 6 parts of boron nitride and 27 parts of 4 mol / L sodium hydroxide solution are mixed uniformly, stirred at 75°C for 11 hours, heated to 115°C for reaction for 11 hours, cooled to room temperature, filtered, washed, and dried to obtain hydroxylated boron nitride; 6 parts of hydroxylated boron nitride and 108 parts of anhydrous ethanol, 18 parts of deionized water, and 3.6 parts of a macromolecular coupling agent are mixed uniformly, acetic acid is added to adjust the pH value to 4.0, reacted at 60°C for 7 hours, filtered, washed, and dried to obtain modified boron nitride;

[0089] Step (2): under nitrogen protection, 2 parts of lithium chloride are dispersed in 56 parts of N-methyl-2-pyrrolidone, 0.56 parts of sodium hydroxide, 23 parts of p-dichlorobenzene, 2.3 parts of 2,5-dichlorobenzoic acid and 1.5 parts of anhydrous sodium sulfide are added and mixed evenly, the mixture is heated to 230° C., reacted for 7 hours, and washed and dried to obtain carboxylated polyphenylene sulfide;

[0090] Step (3): uniformly mix 1 part of carboxylated polyphenylene sulfide and 14 parts of N,N-dimethylformamide, add 6 parts of modified boron nitride and 0.4 parts of tetrabutylammonium bromide, react at 80°C for 6 hours, cool to 55°C, add 3 parts of sodium hydroxide, continue to react for 3 hours, wash, and distill under reduced pressure to obtain a radiation-resistant additive;

[0091] Compared with Example 2, in step (3) of Comparative Example 4, the mass ratio of carboxylated polyphenylene sulfide to modified boron nitride is 1:6, and the other steps are the same as those in Example 2.

[0092] Experiment: Take the protective cover materials obtained in Examples 1-3 and Comparative Examples 1-4, prepare samples, test their properties respectively and record the test results:

[0093] The oxygen index was determined according to the national standard GB / T 10707 "Determination of combustion properties of rubber", and the sample size was 125 mm × 6.5 mm × 3 mm. The protective cover materials obtained in Examples 1-3 and Comparative Examples 1-4 were irradiated with gamma rays (2000 kGy), and the tensile strength before and after irradiation was determined according to the national standard GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", with a tensile speed of 500 mm / min, and the tensile strength retention rate and the elongation at break retention rate were calculated.

[0094] Test Results

[0095]

[0096] According to the data in the above table, we can clearly draw the following conclusions:

[0097] 1. Compared with Examples 1-3, the oxygen index and tensile strength of the products obtained in Comparative Examples 1 and 2 are both reduced, indicating that the modified carbon black prepared by the present invention has better flame retardant effect and compatibility than carbon black, thereby effectively improving the flame retardant properties and mechanical properties of the material; compared with 3-glycidyloxypropyltrimethoxysilane, the macromolecular coupling agent prepared by the present invention has better modification effect, thereby improving the compatibility between the inorganic filler and the polymer matrix.

[0098] 2. Compared with Examples 1-3, the tensile strength retention rate and elongation at break retention rate of the product obtained in Comparative Example 3 are both reduced, which indicates that the radiation-resistant additive prepared by the present invention has excellent radiation resistance and compatibility. Compared with boron nitride, the additive can better improve the mechanical properties of the material in a radiation environment and is suitable for use in nuclear power plants.

[0099] 3. Compared with Examples 1-3, the tensile strength retention rate and elongation at break retention rate of the product obtained in Comparative Example 4 are both reduced. It can be seen that when the addition amount of carboxylated polyphenylene sulfide is reduced, the radiation resistance of the radiation-resistant additive will be reduced.

[0100] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A method for preparing a strong radiation resistant nuclear power plant top cable, characterized in that: The steps include: Step S1: Wrap the shielding tape around the wire core to form a shielding layer; Step S2: Extruding an insulating material onto the outer side of the shielding layer to form an insulating layer; Step S3: adding EPDM rubber, ethylene-vinyl acetate copolymer and chlorinated polyethylene into an internal mixer, mixing at 95-105° C. for 2-3 min, adding modified carbon black, white carbon black, paraffin, radiation-resistant additive, stearic acid, zinc oxide, montmorillonite, antioxidant and ultraviolet absorber, mixing at 145-155° C. for 10-15 min, draining the rubber to obtain a rubber compound; mixing the rubber compound with a cross-linking sensitizer, sulfur and an accelerator, and mixing the mixture to obtain a rubber compound; irradiating and vulcanizing the mixture to obtain a protective sheath material; extruding the protective sheath material onto the outer side of the insulating layer to form a sheath layer to obtain a strong radiation-resistant nuclear power plant top cable; The preparation method of the radiation-resistant auxiliary agent is as follows: Step (1): evenly mix boron nitride and sodium hydroxide solution, stir at 70-80° C. for 10-12 hours, heat to 110-120° C. for reaction for 10-12 hours, cool to room temperature, filter, wash, and dry to obtain hydroxylated boron nitride; evenly mix hydroxylated boron nitride, anhydrous ethanol, deionized water, and a macromolecular coupling agent, add acetic acid to adjust the pH value to 3.5-4.0, react at 50-70° C. for 6-8 hours, filter, wash, and dry to obtain modified boron nitride; Step (2): under nitrogen protection, dispersing lithium chloride in N-methyl-2-pyrrolidone, adding sodium hydroxide, p-dichlorobenzene, 2,5-dichlorobenzoic acid and anhydrous sodium sulfide, mixing evenly, heating to 220-230° C., reacting for 5-7 hours, washing and drying to obtain carboxylated polyphenylene sulfide; Step (3): mix carboxylated polyphenylene sulfide and N,N-dimethylformamide evenly, add modified boron nitride and tetrabutylammonium bromide, react at 70-80°C for 4-6h, cool to 45-55°C, add sodium hydroxide, continue to react for 2-3h, wash and distill under reduced pressure to obtain a radiation-resistant additive.

2. The method for preparing a strong radiation resistant nuclear power plant pile top cable according to claim 1, characterized in that: The insulating material is radiation cross-linked polyethylene.

3. The method for preparing a strong radiation resistant nuclear power plant pile top cable according to claim 1, characterized in that: The protective cover material includes the following components by weight: 70-80 parts of EPDM rubber, 10-20 parts of ethylene-vinyl acetate copolymer, 15-25 parts of chlorinated polyethylene, 20-30 parts of modified carbon black, 10-20 parts of white carbon black, 4-8 parts of cross-linking sensitizer, 2-4 parts of sulfur, 1-3 parts of paraffin, 4-12 parts of radiation-resistant additive, 1-3 parts of stearic acid, 3-5 parts of zinc oxide, 2-4 parts of montmorillonite, 2-4 parts of antioxidant, 1-2 parts of accelerator, and 0.2-0.5 parts of ultraviolet absorber.

4. The method for preparing a strong radiation resistant nuclear power plant pile top cable according to claim 1, characterized in that: The preparation method of the modified carbon black is as follows: Under nitrogen protection, the macromolecular coupling agent and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide are mixed evenly, the temperature is raised to 120-130°C, triphenylphosphine is added, the reaction is carried out for 6-8h, the temperature is lowered to 40-50°C, 4-hydroxyphenylboric acid is added, the reaction is continued for 2-4h, and the flame retardant is obtained after filtering, washing and drying; carbon black, anhydrous ethanol, deionized water and flame retardant are mixed evenly, acetic acid is added to adjust the pH value to 3.5-4.0, the reaction is carried out at 50-70°C for 8-10h, and the modified carbon black is obtained after filtering, washing and drying.

5. The method for preparing a strong radiation resistant nuclear power plant pile top cable according to claim 4, characterized in that: The preparation method of the macromolecular coupling agent is as follows: Under nitrogen protection, EPDM rubber and toluene are mixed evenly, glycidyl methacrylate and γ-methacryloxypropyltrimethoxysilane are added, the temperature is raised to 80-90°C, a mixed solution of benzoyl peroxide and toluene is added dropwise, the dripping is completed in 30-50 minutes, the reaction is carried out for 8-12 hours, and a macromolecular coupling agent is obtained after precipitation and drying.

6. The method for preparing a strong radiation resistant nuclear power plant pile top cable according to claim 1, characterized in that: The cross-linking sensitizer is one of triallyl cyanurate and triallyl isocyanurate.

7. The method for preparing a strong radiation resistant nuclear power plant pile top cable according to claim 1, characterized in that: The antioxidant is prepared by compounding antioxidant 4010NA and antioxidant 2246 in a mass ratio of 1:

1.

8. The method for preparing a strong radiation resistant nuclear power plant pile top cable according to claim 1, characterized in that: The accelerator is accelerator CZ.

9. A strong radiation resistant nuclear power plant stack top cable made according to the preparation method according to any one of claims 1 to 8.

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