JP2010027291A - Radiation-resistant cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation-resistant cable which is superior in heat resistance, radiation resistant characteristics, waterproofness, and flame-resistance, and which does not contain lead. <P>SOLUTION: The radiation-resistant cable includes a composition containing: a chlorine-containing polymer; layered inorganic compound which captures chlorine-containing polymer desorbed from the polymer and crosslink the polymer; a flame retardant; a processing aid; and an antiaging agent, at the surrounding of conductors covered with insulated material or of a plurality numbers of twisted insulated electric wire (core) formed by twisting a plurality numbers of conductors covered with insulated material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radiation resistant cable. In particular, the present invention relates to a radiation-resistant cable that is used in nuclear power plants and the like and does not contain lead.

  At a nuclear power plant such as a boiling water reactor (BWR), an improved boiling water reactor (ABWR), or a pressurized water reactor (PWR) The wires and cables used are exposed to heat and radiation during the steady operation of each reactor operated under the specified operating conditions, and are also exposed to heat and radiation in the event of a loss of coolant, fire, etc. Exposed at the same time. Therefore, electric wires and cables used in nuclear power plants are required to have high flame retardancy and radiation resistance in consideration of these accidents.

Resurge (PbO) and red lead (Pb ₂ O ₃ ) are sheath materials for radiation-resistant cables that have heat resistance, radiation resistance, water resistance, and flame resistance while retaining mechanical and electrical characteristics. Polychloroprene rubber (CR) or chlorosulfonated polyethylene (CSM) to which a lead compound such as the above is added as a vulcanizing agent is used. For example, if a coolant loss accident occurs, the conditions such as heat, radiation dose, and high-pressure steam to which the radiation-resistant cable is exposed in this accident are more severe in PWR than in BWR. Become. Therefore, CSM, which is superior in heat resistance, radiation resistance and chemical resistance to CR, is mainly used as a sheath material for radiation resistant cables used in PWR. In BWR, in which various conditions such as heat, radiation dose, and high-pressure steam to which the radiation-resistant cable is exposed compared to PWR are not severe, a CR sheath is mainly used as a sheath material for the radiation-resistant cable.

  Conventionally, there has been known a radiation resistant cable in which a sheath is formed from a composition containing 20 to 80 parts by weight of aromatic oil having an aromatic amount of 30% by weight or more with respect to 100 parts by weight of chlorosulfonated polyethylene having a predetermined viscosity. (For example, refer to Patent Document 1). Resurge is blended in the radiation resistant cable as a vulcanizing agent. Further, as a radiation-resistant polymer composition that is a sheath material of a radiation-resistant cable that does not contain a lead compound and contains zinc oxide or the like, a polymer containing 3 to 70 parts by weight of a polymer component such as butyl rubber and an ethylene unit as main components. A radiation-resistant polymer composition is known in which 3 parts by weight or more of a softening agent is added to 100 parts by weight of a polymer component composed of 97 to 30 parts by weight of a second polymer component such as , See Patent Document 2).

  Since the radiation resistant cable described in Patent Document 1 uses chlorosulfonated polyethylene having a predetermined viscosity, a radiation resistant cable having practically sufficient mechanical strength can be provided. Moreover, since the radiation resistant polymer composition described in Patent Document 2 is produced by adding each material at the above-mentioned predetermined mixing ratio, a large amount of radiation is applied to the radiation resistant polymer composition. Even after irradiation, deterioration of the surface hardness, breaking strength, and breaking elongation of the radiation-resistant polymer composition can be suppressed.

JP-A-2-227914 JP 2005-48129 A

  However, since the radiation resistant cable described in Patent Document 1 contains a lead compound in the sheath, environmental hygiene at the cable manufacturing site is not preferable, and the lead compound is eluted from the sheath after the radiation resistant cable is discarded. There is. Further, although the radiation resistant polymer composition described in Patent Document 2 does not contain a lead compound, there is a problem in water resistance, and the sheath material absorbs the coolant by the high pressure steam at the time of occurrence of the coolant loss accident. In some cases, the mechanical properties and electrical properties of the radiation-resistant cable having the sheath material are deteriorated.

  Accordingly, an object of the present invention is to provide a radiation-resistant cable that is excellent in heat resistance, radiation resistance, water resistance, and flame retardancy and does not contain lead.

  In order to achieve the above object, the present invention provides a polymer containing chlorine, a layered inorganic compound that captures chlorine desorbed from the polymer and crosslinks the polymer, a flame retardant, a processing aid, and an antioxidant. There is provided a radiation-resistant cable comprising a conductor containing an insulating material around a stranded insulated electric wire (core) formed by twisting a conductor coated with an insulating material or a plurality of conductors coated with an insulating material.

  In the radiation resistant cable, the layered inorganic compound may be a hydrotalcite compound. The polymer may be formed to include one or more chlorine-containing polymer compounds selected from the group consisting of polychloroprene rubber, chlorosulfonated polyethylene, and chlorinated polyethylene, and the polymer has a chlorination degree. It can be formed comprising 30% to 40% chlorosulfonated polyethylene or chlorinated polyethylene. Further, the flame retardant is antimony trioxide, the processing aid may be a process oil, and the composition is 100 parts by weight of the polymer, 5 parts by weight or more of the layered compound, 1 part by weight or more of the flame retardant, It can be formed by adding 5 parts by weight or more of processing aid and 2 parts by weight or more of anti-aging agent. Furthermore, the process oil may be an aromatic oil, and the anti-aging agent can be formed by combining an amine-based anti-aging agent and a sulfur-based anti-aging agent.

  According to the radiation-resistant cable according to the present invention, it is possible to provide a radiation-resistant cable that is excellent in heat resistance, radiation resistance, water resistance, and flame retardancy and does not contain lead.

[Embodiment]
(Outline of radiation-resistant cable configuration)
A radiation-resistant cable according to an embodiment of the present invention includes a polymer containing chlorine, a layered inorganic compound that captures chlorine desorbed from the polymer and crosslinks the polymer, a flame retardant, a processing aid, and anti-aging. A composition as a sheath material for a radiation-resistant cable including an agent is provided around a conductor coated with an insulating material. In addition, the radiation resistant cable according to the present embodiment is formed by including the sheath material for the radiation resistant cable around a twisted insulated wire (core) formed by twisting a plurality of conductors coated with an insulating material. You can also

  Here, the sheath material for a radiation resistant cable used in the radiation environment according to the present embodiment is a predetermined amount of layered inorganic compound, a predetermined amount of flame retardant, and a predetermined amount of polymer containing chlorine, It is formed by adding a predetermined amount of processing aid and a predetermined amount of anti-aging agent. Moreover, the sheath material for radiation resistant cables according to the present embodiment can be formed by further adding a predetermined compounding agent. The radiation resistant cable according to the present embodiment can be applied to, for example, an electric cable used in a nuclear power plant.

(Chlorine-containing polymer compound)
The chlorine-containing polymer according to the present embodiment, that is, the chlorine-containing polymer compound is formed to include at least one of polychloroprene rubber (CR), chlorosulfonated polyethylene (CSM), and chlorinated polyethylene. . Specifically, the chlorine-containing polymer compound according to the present embodiment has one of the following three forms. First, a 1st form is a chlorine containing high molecular compound formed including any one of CR, CSM, and chlorinated polyethylene. The second form is a chlorine-containing polymer compound containing CR and CSM, a chlorine-containing polymer compound containing CR and chlorinated polyethylene, or a chlorine-containing polymer compound containing CSM and chlorinated polyethylene. is there. And the 3rd form is a chlorine containing high molecular compound containing all of CR, CSM, and chlorinated polyethylene.

  Here, for the purpose of realizing the elasticity required for the radiation resistant cable according to the present embodiment, the CSM is a CSM having a chlorination degree that exhibits appropriate rubber elasticity. For example, CSM having a chlorination degree of 30% to 40% is used. Unlike CR, CSM has excellent heat resistance, weather resistance, and ozone resistance because it does not have a double bond in the main chain. In addition, CSM is superior in chemical resistance (particularly resistance to alkaline chemicals) compared to CR.

  In addition, when using the radiation-resistant cable sheath material according to the present embodiment for the radiation-resistant cable sheath used in the BWR, it is preferable to use a mixed material obtained by mixing a predetermined amount of CR with a predetermined amount of CSM. In addition, as a chlorine-containing polymer compound, a mixed material obtained by mixing chlorinated polyethylene and CR, which exhibits rubber elasticity and does not have a double bond in the main chain, may be used as a sheath material for radiation resistant cables used in BWRs. it can.

(Layered inorganic compound)
The layered inorganic compound as the vulcanizing agent and stabilizer according to the present embodiment is, for example, a hydrotalcite compound as a layered double hydroxide having an anion exchange function. The hydrotalcite compound is a layered inorganic compound represented by a general formula [M 2 ⁺ _1-x M ³⁺ _x (OH) ₂ ] [A ⁿ⁻ _{x / n} · ZH ₂ O]. ^{Here, M 2+} is a divalent metal ^{ion, M 3+} is a trivalent metal ^{ion, A n-anions} (anions). As the hydrotalcite compound according to the present embodiment, either a natural product or a synthetic product can be used. Incidentally, the hydrotalcite is naturally occurring in ^{M 2+: M 3+: A n-} = Mg 2+: Al 3+: CO 3 ^2-.

  The range of x is 0 <x <1. Here, the range of x is preferably 0.3 ≦ x ≦ 0.33 for the purpose of suppressing an increase in instability as a crystal due to a decrease in bonding between layers. Further, since the hydrotalcite compound crystals are stabilized by the presence of interlayer water, the range of Z is preferably 0 <Z. In addition, the flame resistance can be provided to the sheath material for radiation-resistant cables according to the present embodiment by removing the interlayer water of the hydrotalcite compound from the interlayer.

  While exhibiting water resistance to the sheath material for radiation-resistant cable according to the present embodiment, and adding antimony trioxide as a flame retardant, for the purpose of suppressing the production of antimony chloride in reverse sequential degradation, 5 parts by weight or more, preferably 20 parts by weight or more of hydrotalcite compound is added to 100 parts by weight of the chlorine-containing polymer compound. 100 weight of chlorine-containing polymer compound for the purpose of stabilizing the captured chlorine by appropriately vulcanizing the sheath material for radiation-resistant cable and capturing chlorine (chlorine ions) in hydrogen chloride. It is preferable to add 5 parts by weight or more of hydrotalcite compound with respect to parts. And it is preferable to add the hydrotalcite compound in an amount within a range in which the mechanical properties of the sheath material for radiation resistant cable do not deteriorate to 100 parts by weight of the chlorine-containing polymer compound. 50 parts by weight or less is preferable with respect to 100 parts by weight of the compound.

  The hydrotalcite compound has interlayer water between layers. The interlayer water gradually desorbs from the interlayer from about 190 ° C. Since the skeleton of the hydrotalcite compound is a metal hydroxide, the hydrotalcite compound from which interlayer water has been removed from the interlayer improves the function as a flame retardant. Therefore, by removing a predetermined amount of interlayer water from the interlayer of the hydrotalcite compound, the function as flame retardancy of the sheath material for radiation resistant cable can be improved. Furthermore, by adding a hydrotalcite compound to the sheath material for radiation-resistant cables, compared with the case where it is not added, a decrease in mechanical properties after radiation irradiation can be suppressed, and radiation resistance is also improved.

  When a sheath material is formed using magnesium oxide or the like as a substitute for a lead compound as a vulcanizing agent, when hydrogen chloride is desorbed from CR or CSM, the desorbed hydrogen chloride reacts with magnesium oxide or the like. As a result, metal chloride is formed. For example, magnesium chloride has deliquescence, so when magnesium chloride is formed in a sheath material formed by adding magnesium oxide or the like, the magnesium chloride takes in moisture in the air and the water resistance of the sheath material decreases. To do.

  Here, as a method for evaluating a sheath material for a radiation-resistant cable as a cable covering material, there is a method (sequential deterioration method) in which radiation is irradiated after thermal deterioration. This is a technique adopted because it is difficult to apply heat and radiation to the cable covering material at the same time because a special device is required. However, since electrical cables used in nuclear power plants are exposed to heat and radiation at the same time, a reverse sequential method in which the sheath material deteriorates compared to simultaneous irradiation of heat and radiation, that is, after irradiation with radiation, A method of deteriorating is also considered.

  And when antimony trioxide is added to the sheath material, and the compound that captures hydrogen chloride desorbed from the CR and CSM is not added to the sheath material (or although it captures hydrogen chloride) In the case where only a compound having a low scavenging ability is added to the sheath material), hydrogen chloride desorbed from CR and CSM reacts with antimony trioxide to produce antimony chloride. For example, antimony trioxide is added to the sheath material for the purpose of improving flame retardancy, and an accelerated test of reverse sequential degradation (reverse sequential method) is performed on the sheath material added with magnesium oxide as a lead compound substitute. When applied, the present inventor has obtained the knowledge that antimony chloride precipitates in powder form on the surface of the sheath material.

  In contrast to the sequential degradation method, the inverse sequential method is a method in which the sheath material is irradiated with radiation and then thermally degraded. Therefore, radicals generated in the sheath material by irradiation with radiation (gamma rays) are actively moved by thermal deterioration applied to the sheath material after irradiation with radiation, and the dechlorination action by radicals is promoted. Therefore, it was considered that the deterioration of the properties of the sheath material was more remarkable in the inverse sequential method than in the sequential deterioration method.

  This is because the ability to stabilize hydrogen chloride generated from chlorine-containing polymer compounds is lower in lead compound substitutes such as magnesium oxide than in lead compounds. It was thought that hydrogen chloride desorbed from the chlorine-containing polymer compound could not be captured by the lead compound substitute. The precipitation of antimony chloride on the surface of the sheath material, that is, the surface of the cable, is preferably suppressed from the viewpoint of flame retardancy, water resistance, and appearance.

On the other hand, the hydrotalcite compound according to the present embodiment has a function as a vulcanizing agent and a function of sufficiently capturing chlorine of hydrogen chloride desorbed from chlorine-containing polymer compounds such as CR and CSM. . Specifically, hydrogen chloride intercalates between the layers of the hydrotalcite compound, and an anion existing between the layers is exchanged with chlorine of hydrogen chloride (exchange reaction). For example, chlorine ions are trapped between the layers by an exchange reaction of A ⁿ⁻ + HCl → HA ⁿ⁻ + Cl ⁻ between the layers of the hydrotalcite compound.

  As a result, the hydrotalcite compound captures chlorine ions of hydrogen chloride desorbed from CR and CSM. In this embodiment, metal chloride is present in the sheath material for the radiation resistant cable and on the surface of the sheath material. Generation can be prevented. Therefore, the sheath material for radiation resistant cables according to the present embodiment has excellent water resistance. The chlorine ions captured by the hydrotalcite compound do not desorb from the hydrotalcite compound up to a temperature of about 500 ° C. and exist stably.

  Furthermore, since the hydrotalcite compound captures chlorine (ions) of hydrogen chloride desorbed from CR and CSM, antimony trioxide and hydrogen chloride added to the sheath material for radiation-resistant cables for the purpose of improving flame retardancy Can be suppressed. That is, in the present embodiment, the formation of antimony chloride can be suppressed by adding the hydrotalcite compound to the sheath material for radiation-resistant cables. Thereby, the outstanding water resistance can be provided to the sheath material for radiation resistant cables according to the present embodiment.

(Anti-aging agent)
The anti-aging agent according to the present embodiment imparts a function of maintaining heat resistance and a function of exhibiting radiation resistance to the sheath material for radiation resistant cable. As the anti-aging agent, a phenol-based primary anti-aging agent or an amine-based primary anti-cleaning agent can be used. The anti-aging agent may be a sulfur-based secondary anti-aging agent or a phosphorus-based secondary anti-aging agent. Specifically, the anti-aging agent according to the present embodiment is used in combination with a primary anti-aging agent and a secondary anti-aging agent for the purpose of imparting resistance to thermal degradation and radiation degradation to the sheath material for radiation-resistant cables. To do. More specifically, the anti-aging agent according to the present embodiment uses an amine-based anti-aging agent and a sulfur-based anti-aging agent in combination for the purpose of improving heat resistance and radiation resistance.

  The anti-aging agent makes the total of the primary anti-aging agent and the secondary anti-aging agent 2 parts by weight or more with respect to 100 parts by weight of the chlorine-based polymer. The total of the primary anti-aging agent and the secondary anti-aging agent is 100 parts by weight of the chlorine-based polymer for the purpose of appropriately cross-linking the chlorine-based polymer and reducing the cost in the manufacturing process of the sheath material for the radiation resistant cable. On the other hand, it is desirable to set in the range of 2 to 15 parts by weight.

  The phenolic primary antiaging agents include primary antiaging agents classified into monophenolic, bisphenolic, and polyphenolic types. Examples of the monophenol-based primary anti-aging agent include 2,2′-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, and mono (α-methylbenzyl). ) Etc. can be used. Examples of bisphenol-based primary antiaging agents include 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4 , 4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), butylated reaction product of p-cresol and dicyclopentadiene, Alternatively, di (α-methylbenzyl) or the like can be used. Furthermore, 2,5′-di-t-butylhydroquinone, 2,5′-di-t-amylhydroquinone, tri (α-methylbenzyl) and the like can be used as the polyphenol-based primary antiaging agent. .

  As the amine-based anti-aging agent, a quinoline-based anti-aging agent and an aromatic secondary amine-based anti-aging agent can be used. For example, 2,2,4-trimethyl-1,2-dihydroquinoline or 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline can be used as the quinoline-based antioxidant. . Aromatic secondary amine type antioxidants include, for example, phenyl-1-naphthylamine, alkylated diphenylamine, octylated diphenylamine, 4,4′-bis (α, α-dimethylbenzyl) dienylamine, p- (p- Toluenesulfonylamido) diphenylamine, N, N′-di-2-naphthyl-p-phenylenediamine, N, N′-diphenyl-p-phenylenediamine, N-phenyl-N′-isopropyl-p-phenylenediamine, N— Phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine, N-phenyl-N ′-(3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine, or the like can be used.

  There are secondary anti-aging agents classified into benzimidazole-based, dithiocarbamate-based, thiourea-based, and organic thioacid-based sulfur-based secondary anti-aging agents. For example, 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, or zinc salt of 2-mercaptobenzimidazole can be used as the benzimidazole-based secondary antiaging agent. As the dithiocarbamate-based secondary antiaging agent, for example, nickel diethyldithiocarbamate or nickel dibutyldithiocarbamate can be used. Furthermore, for example, 1,3-bis (dimethylaminopropyl) -2-thiourea or tributylthiourea can be used as the thiourea-based secondary antiaging agent. Furthermore, dilauryl thiodipropionate or the like can be used as the organic thioacid-based secondary antiaging agent.

  As the phosphorous secondary anti-aging agent, for example, tris (nonylphenyl) phosphite can be used as the phosphorous acid system.

  An anti-aging agent comprising a plurality of anti-aging agents selected from an amine-based anti-aging agent, a phenol-based anti-aging agent, a sulfur-based anti-aging agent and / or a phosphorus-based anti-aging agent. A mixed product (mixed product made into one pack) can also be used as an anti-aging agent according to the present embodiment.

(Processing aid)
The processing aid according to the present embodiment functions as a compounding agent that stabilizes the processability during the kneading or extrusion of the sheath material for radiation-resistant cable and functions as a radiation protective agent (anti-rad) having radiation resistance. To the sheath material for radiation resistant cable. As the processing aid, for example, petroleum-based oil (that is, process oil) or ester plasticizer containing an aromatic ring (benzene ring) can be used.

  As the process oil, for example, a mineral oil such as paraffinic oil, aromatic (aromatic) oil, or naphthenic oil added to a rubber material or the like can be used. Examples of the ester plasticizer include bis (2-ethylhexyl) phthalate (DOP), diisononyl phthalate (DINP), and diisodecyl phthalate (DIDP) added to polyvinyl chloride and the like. Alternatively, a plasticizer having an aromatic ring in the molecule, such as trimellitic acid tri-2-ethylhexyl (TOTM), can be used.

  Here, since a compound containing a large amount of a benzene ring compound is excellent in radiation resistance, it is preferably used as a processing aid according to the present embodiment. For example, an aromatic oil can be used as a processing aid. . As the processing aid, either process oil or ester plasticizer is used alone, or a mixture of a plurality of compounds selected from process oil and / or ester plasticizer is used. Can do.

  For the purpose of ensuring an appropriate viscosity and workability and imparting an anti-rad effect to the sheath material for radiation-resistant cables, the amount of processing aid added is 100 parts by weight of the polymer containing chlorine. 5 parts by weight or more. Further, when the amount of the processing aid is more than 50 parts by weight with respect to 100 parts by weight of the polymer containing chlorine, bleeding tends to occur, the mechanical properties are deteriorated, and the effect as an anti-rad. Is saturated. Accordingly, the processing aid is added to the radiation-resistant cable sheath material in the range of 5 to 50 parts by weight with respect to 100 parts by weight of the polymer containing chlorine.

(Flame retardants)
As the flame retardant, antimony trioxide as an inorganic flame retardant can be used, and in addition, a metal hydroxide or a phosphorus flame retardant can be used. Although the suppression of the reaction between antimony trioxide and hydrogen chloride when antimony trioxide is used has been described above, even if a metal hydroxide or a phosphorus-based flame retardant is used, Thus, the reaction between these flame retardants and hydrogen chloride can be suppressed. The flame retardant is added to the sheath material for a radiation resistant cable as long as the flame retardant effect is exhibited and the flame retardant effect is not saturated and the mechanical properties are not deteriorated. Specifically, the flame retardant is added to the radiation-resistant cable sheath material in an amount of 1 part by weight or more with respect to 100 parts by weight of the polymer containing chlorine.

(Other compounding agents)
For example, lubricants, fillers, colorants and the like used in the synthesis of rubber materials can be further used as a compounding agent for the sheath material for radiation-resistant cables according to the present embodiment.

(Conductor etc.)
The conductor coated with the insulating material including the sheath material for radiation-resistant cable according to the present embodiment is formed of a conductive material such as copper or copper alloy, and has a predetermined conductor cross-sectional area. And the surface of a conductor is coat | covered with the insulating material to which the predetermined | prescribed compounding agent was added. Base polymers for insulating materials include, for example, polyethylene, crosslinked polyethylene, ethylene / vinyl acetate copolymer, ethylene / methyl acrylate copolymer, ethylene / ethyl acrylate copolymer, natural rubber, ethylene / propylene rubber, butyl rubber, and chlorosulfone. Polymers such as chlorinated polyethylene or chlorinated polyethylene can be used. The base polymer can also be formed from a polymer blend comprising two or more types of polymers selected from these polymers.

  In the present embodiment, the radiation resistant cable according to the present embodiment can be formed by providing the radiation resistant cable sheath material around the conductor whose surface is covered with the insulating material. The radiation resistant cable according to the present embodiment is provided by providing a sheath material for the radiation resistant cable around a twisted insulated wire (core) formed by twisting a plurality of conductors whose surfaces are coated with an insulating material. Can also be formed.

(Method of manufacturing radiation-resistant cable)
First, a plurality of conductors (insulated wires) coated with an insulating material are prepared. Next, a plurality of prepared insulated wires are twisted together to form a twisted insulated wire (core). Subsequently, a compound for the radiation-resistant sheath material is extruded and covered around the twisted insulated electric wire (core). The compound is prepared by adding a predetermined amount of layered inorganic compound, a predetermined amount of flame retardant, a predetermined amount of processing aid, and a predetermined amount of anti-aging agent to a predetermined amount of chlorine-containing polymer compound. be able to.

  Thereafter, the compound coated with the twisted insulated electric wire (core) is subjected to a crosslinking treatment (for example, treatment with high-pressure steam at a predetermined temperature) to make the compound a sheath material for a radiation-resistant cable. Thereby, the radiation resistant cable which concerns on this Embodiment is obtained. When only one insulated wire is used, a compound is extruded and covered around one insulated wire, and the subsequent steps are the same as those of the radiation-resistant cable according to the present embodiment. Provides one radiation-resistant cable.

(Effect of embodiment)
Since the radiation resistant cable according to the embodiment of the present invention has added the hydrotalcite compound as a layered inorganic compound to the sheath material for radiation resistant cable, from the chlorine-containing polymer compound contained in the sheath material for radiation resistant cable, For example, even when hydrogen chloride is desorbed, chlorine ions in hydrogen chloride can be trapped between the layers of the hydrotalcite compound. Thereby, since it can suppress that a metal chloride produces | generates in the sheath material for radiation resistant cables, it can suppress that the sheath material for radiation resistant cables takes in water. Therefore, according to the present embodiment, it is possible to provide a radiation resistant cable that does not contain a lead compound and is excellent in water resistance, flame retardancy, heat resistance, and radiation resistance. In particular, since a layered inorganic compound as a substitute for a lead compound is used without containing lead as a vulcanizing agent, environmental hygiene can be considered.

  FIG. 1 shows an outline of a cross section of a radiation resistant cable according to an embodiment of the present invention.

  A radiation resistant cable 1 according to an embodiment of the present invention includes a conductor 10, an insulator 15 as an insulating material covering the conductor 10, and a sheath material for a radiation resistant cable covering the conductor 10 from the outside of the insulator 15. A sheath 20. The radiation resistant cable 1 includes one or more conductors 10. When the radiation-resistant cable 1 includes a plurality of conductors 10, the plurality of conductors 10 are twisted together to form a twisted insulated wire (core), and along the outer periphery of the twisted insulated wire (core) ( The sheath 20 is formed by covering the outer periphery.

  Table 1 shows the composition of the compound that forms the sheath material for a radiation-resistant cable according to the example of the present invention and the composition of the compound that forms the sheath material according to the comparative example.

In Table 1, as the chlorine-containing polymer compound, polychloroprene (Shoprene W (registered trademark), manufactured by Showa Denko KK), chlorosulfonated polyethylene (Hypalon 40 (registered trademark), manufactured by DuPont Elastomer Co., Ltd., chlorination degree) 35%) and chlorinated polyethylene (Daisolac (registered trademark) CM, manufactured by Daiso Corporation). As the hydrotalcite compound, hydrotalcite (STABIACE HT-1 Mg ₄ Al ₂ (OH) ₁₂ (CO) ₃ .3H ₂ O, manufactured by Sakai Chemical Industry Co., Ltd.) was used.

  Further, tetramethyltyrium monosulfide (accelerator TS) was used as a vulcanization accelerator. Furthermore, Diana process oil AH-16 (made by Idemitsu Kosan) was used as an aromatic oil as a processing aid. And as an anti-aging agent, Vulkanox (registered trademark) DDA (manufactured by Bayer), which is an amine-based anti-aging agent, and Nocrack NBC (manufactured by Ei Ouchi), which is an anti-aging agent, were used. As one of the flame retardants, calcium carbonate (Softon 1200 (registered trademark), manufactured by Bihoku Powdered Industries) was used.

  Table 2 shows the compounding ratios of the compounds constituting the insulator covering the conductors according to the examples and comparative examples of the present invention.

  Ethylene-propylene-diene rubber (EPDM, EPT3045, manufactured by Mitsui Chemicals) was used as a polymer insulating material for forming the insulator 15, and Vulkanox (registered trademark) DDA (manufactured by Bayer) was used as an amine-based anti-aging agent. . Moreover, Diana process oil AH-16 (made by Idemitsu Kosan) was used as the aromatic oil as a processing aid. Furthermore, high filler # 16 (manufactured by Tsuchiya Kaolin) was used as talc, and Cytex 8010 (manufactured by Albemarle Asano) was used as a brominated flame retardant.

(Production of radiation-resistant sheath material and radiation-resistant cable)
The compound for the radiation resistant sheath material according to the present example and the comparative example was manufactured as follows. First, each compound shown in Table 1 was weighed for each of Examples and Comparative Examples. Next, each Example and Comparative Example were kneaded using a Banbury mixer to obtain a compound (for example, the compound according to Example 1, the compound according to Example 2, etc.).

In addition, a flame-retardant EP rubber insulated wire core was prepared. The flame retardant EP rubber insulated wire core is formed by extruding and covering the surface of a conductor having a cross-sectional area of 3.5 mm ² with a thickness of 2.9 mm by insulating material obtained by blending at a blending ratio shown in Table 2. The insulating material covered with high-pressure steam at 190 ° C. was cross-linked and manufactured. The oxygen index of the insulator 15 of the flame-retardant EP rubber insulated wire core was 26.0. In all of the examples and comparative examples, the flame retardant EP rubber insulation core used is the same.

  Then, three flame-retardant EP rubber insulated wires were twisted together to produce a twisted insulated wire (core). Then, the compound for the manufactured radiation-resistant sheath material was extrusion-coated around the twisted insulated wire (core) using a 90 mm extruder. That is, for each of the example and the comparative example, the surface of the twisted insulated wire (core) was coated with a compound (for example, the compound for the radiation-resistant sheath material according to Example 1 of the twisted insulated wire (core) The surface was coated.)

  Subsequently, the compound was cross-linked by bringing pressurized steam at about 190 ° C. into contact with the surface of the twisted insulated electric wire (core) that was extrusion-coated with the compound for the radiation-resistant sheath material. Thereby, the sheath 20 which consists of a radiation-resistant sheath material was formed around the twisted insulated electric wire (core), and the radiation-resistant cable of outer diameter 17.5mm was obtained for each of the Example and the comparative example.

(Characteristic test of radiation resistant cable)
Next, the obtained radiation-resistant cable was evaluated by performing tests on the following items. For radiation resistant cables according to Examples and Comparative Examples using polychloroprene rubber as the chlorine-containing polymer compound, evaluation was performed under BWR conditions, and chlorosulfonated polyethylene was used as the chlorine-containing polymer compound. The radiation resistant cables according to the examples and comparative examples were evaluated under PWR conditions.

  FIG. 2 shows conditions in the LOCA simulation test under the BWR condition, and FIG. 3 shows conditions in the LOCA simulation test under the PWR condition.

(Characteristic test items)
Test (A) Appearance: The presence or absence of bloom (the compounding agent was precipitated as powder on the sheath surface) and bleed (the compounding agent leaked as a liquid on the sheath surface) was visually confirmed.
Test (B) Sheath material tensile test: After the sheath material was peeled from the radiation-resistant cable, the thickness was adjusted to about 2 mm and punched into a dumbbell No. 4 shape at a speed of 500 mm / min in a shopper type tensile tester. It was measured.
Test (C) VTFT test: IEEE Std. 383-2003 (according to IEEE Std. 1202-1991).
Test (D-1) Radiation resistance (1) (BWR condition reverse sequential method test (1)): A radiation-resistant cable was rolled into a bundle of about 600 mmφ, and 760 kGy at a dose rate of 4 kGy / h with ⁶⁰ Coγ rays. After the irradiation, a heat aging test was conducted at 121 ° C. for 7 days. Then, the tension test was implemented like the test (B). Here, the case where elongation was 50% or more was determined to be acceptable.
Test (D-2) radiation resistance (2) (reverse sequential method tests PWR condition (2)): rounding a bunch of radiation-resistant cable about ^600Mmfai, 2 at a dose rate of 4 kGy / h at 60 Co gamma rays. After irradiation with 3MGy, a heat aging test was conducted at 140 ° C. for 9 days. Then, the tension test was implemented like the test (B). Here, the case where elongation was 50% or more was determined to be acceptable.
Test (E-1) LOCA simulation test under BWR condition: A radiation-resistant cable was rolled into a bundle of about 600 mmφ, and the test was carried out under the conditions shown in FIG. The case where the radiation-resistant cable after the LOCA simulation test did not cause a short circuit and the external appearance did not deteriorate enough to be visually discerned was regarded as acceptable. The simulation test also serves as a water resistance test.
Test (E-2) LOCA simulation test under the PWR condition: A radiation-resistant cable was rolled into a bundle of about 600 mmφ, a heat aging test was conducted at 141 ° C. × 9 days, and a dose rate of 4 kGy / h with ⁶⁰ Coγ rays 2.3 MGy irradiation was performed. And the LOCA simulation test was implemented on the conditions of FIG. The case where the radiation-resistant cable after the LOCA simulation test did not cause a short circuit and the appearance was not deteriorated to the extent that it could be visually discerned was regarded as acceptable. The simulation test also serves as a water resistance test.

  Here, the radiation resistant cable containing the lead compound was rejected from the viewpoint of environmental considerations. The elongation in test (B) was calculated as follows. That is, a marked line of a predetermined length (for example, L0 = 20 mm) is attached to the center portion (width 5 mm, length 20 mm or more) of the dumbbell test piece with a constant interval L0, and this dumbbell test piece is measured with a tensile tester. Pulling and breaking the dumbbell specimen. And the distance between marked lines at the time of a fracture | rupture of a dumbbell test piece was set to L1, and elongation E0 was computed using E0 = {(L1-L0) / L0} * 100 (Formula 1).

  Table 3 shows the result of the characteristic test of the radiation resistant cable according to the example of the present invention and the comparative example.

  Referring to Table 3, all of the radiation resistant cables according to Examples 1 to 7 passed in all the tests.

  On the other hand, in the radiation resistant cable according to Comparative Example 1, the amount of hydrotalcite added is as small as 3 parts by weight with respect to 100 parts by weight of the chlorine-containing polymer compound, resulting in insufficient vulcanization. The initial elongation was large and the tensile strength was small. Furthermore, in the radiation resistant cable according to Comparative Example 1, hydrogen chloride desorbed from the chlorine-containing polymer compound could not be stabilized, so that the deterioration progressed markedly and became brittle.

  The radiation resistant cable according to Comparative Example 2 was inferior in flame retardancy due to the fact that antimony trioxide was not added, and did not pass the VTFT test. Moreover, although the radiation-resistant cable which concerns on the comparative example 3 passed the LOCA test of a tension test, a VTFT test, radiation resistance, and BWR conditions, since it added lead tan, from a viewpoint on environmental hygiene, it is a failure. did. The radiation resistant cable according to Comparative Example 4 is satisfactory in tensile test, VTFT test, and radiation resistance, but has poor water resistance due to the addition of magnesium oxide as a vulcanizing agent, and the LOCA test is not satisfactory. It was a pass. Furthermore, in Comparative Example 4, magnesium chloride could not be stabilized by the hydrogen chloride desorbed from the chlorine-containing polymer compound, and antimony chloride was deposited on the surface of the radiation-resistant cable.

  In addition, the radiation resistant cable according to Comparative Example 5 was exposed to radiation because the amount of the aromatic oil as the process oil was as small as 3 parts by weight with respect to 100 parts by weight of the chlorine-containing polymer compound. After embrittlement. And the radiation resistant cable which concerns on the comparative example 6 originated in the addition amount of an anti-aging agent being 1 weight part with respect to 100 weight part of chlorine containing high molecular compounds, and became embrittled after exposure to a radiation. .

  According to the comparison between Examples 1 to 7 of the present invention and Comparative Examples 1 to 6, none of the radiation resistant cables according to the examples of the present invention contains heat resistance, radiation resistance, and It was shown to be excellent in water resistance. Therefore, the radiation resistant cable according to Examples 1 to 7 can be applied to, for example, a flame retardant electric wire or cable for a nuclear power plant.

  While the embodiments and examples of the present invention have been described above, the embodiments and examples described above do not limit the invention according to the claims. It should be noted that not all combinations of features described in the embodiments and examples are necessarily essential to the means for solving the problems of the invention.

It is sectional drawing of the radiation resistant cable which concerns on the Example of this invention. It is a figure which shows the conditions in the LOCA simulation test of BWR conditions. It is a figure which shows the conditions in the LOCA simulation test of PWR conditions.

Explanation of symbols

1 Radiation Resistant Cable 10 Conductor 15 Insulator 20 Sheath

Claims (8)

  An insulating material comprises a composition containing a chlorine-containing polymer, a layered inorganic compound that captures chlorine released from the polymer and cross-links the polymer, a flame retardant, a processing aid, and an anti-aging agent. A radiation-resistant cable provided around a twisted insulated electric wire (core) formed by twisting a plurality of conductors covered or covered with the insulating material. The radiation-resistant cable according to claim 1, wherein the layered inorganic compound is a hydrotalcite compound. The radiation-resistant cable according to claim 2, wherein the polymer includes one or more chlorine-containing polymer compounds selected from the group consisting of polychloroprene rubber, chlorosulfonated polyethylene, and chlorinated polyethylene. The radiation resistant cable according to claim 3, wherein the polymer includes the chlorosulfonated polyethylene having a chlorination degree of 30% to 40% or the chlorinated polyethylene. The flame retardant is antimony trioxide;
The radiation-resistant cable according to claim 3, wherein the processing aid is process oil. The composition comprises
The said layered compound is added to 100 parts by weight of the polymer by adding 5 parts by weight or more, 1 part by weight or more of the flame retardant, 5 parts by weight or more of the processing aid, and 2 parts by weight or more of the anti-aging agent. 5. A radiation-resistant cable according to 5. The radiation resistant cable according to claim 6, wherein the process oil is an aromatic oil. The radiation-resistant cable according to claim 7, wherein the anti-aging agent is a combination of an amine-based anti-aging agent and a sulfur-based anti-aging agent.

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