JP5691818B2 - Radiation-resistant insulated wire - Google Patents

Description

  The present invention relates to a flame-resistant composition, particularly a radiation-resistant insulated wire provided with an insulator made of a composition having excellent radiation resistance and electrical characteristics.

  Electric wires and cables used in nuclear power plants are simultaneously exposed to heat and radiation during normal operation and to heat, radiation and hot water during a possible loss of coolant accident (LOCA). . Furthermore, there is a demand for high flame retardancy that simulates the fire of cables laid on a vertical tray.

  The following invention has already been proposed by the present applicant as such a composition, and an electric wire and cable using the composition (see Patent Document 1).

  That is, a polymer containing chlorine, a radiation resistance-imparting material that imparts radiation resistance to the polymer, an amorphous inorganic material that traps ionic components generated in the polymer upon irradiation with radiation, and the mechanical strength of the polymer The development of a radiation-resistant sheath material comprising a reinforcing material in an amount equal to or less than the amount of the amorphous inorganic material is being promoted, and as a result, for BWR (Boiling-Water Reactor) It can be used as a sheath material and a sheath material for PWR (Pressurized-Water Reactor), and also has excellent flame resistance, heat resistance, radiation resistance, and water resistance due to cracking of the sheath. It can cope with the test by the sequential method, and has come to see a solution as a sheath material used for the radiation resistant cable.

JP 2010-53246 A

  However, as the development of imparting flame resistance, heat resistance, and radiation resistance to the insulator located on the conductor, the so-called internal insulator, or the insulating layer in the insulated wire, Radiation resistance is prominent when used as a sheath material, but when used as an internal insulator that is in direct contact with a conductor, the expected effect cannot always be obtained. It has gradually become clear that the dots are lurking.

  In addition to the above characteristics, the insulation layer in this internal insulator or insulated wire has the following characteristics: normal operation and LOCA assumed in a nuclear power plant containment vessel. This means that it is necessary to withstand tests that are exposed to water and to maintain electrical insulation during exposure to hot water.

  Flame retardant insulating materials exposed to heat and radiation have many ionic components due to halogen elimination reaction (hydrogen chloride and odorous hydrogen) from halogen-containing flame retardants or anti-aging agents and alteration of anti-aging agents. In this state, when exposed to hot water, the phenomenon of water absorption is seen easily, and the ionic component is easily moved in the insulator material due to the presence of water (ionic conductivity), so that the electrical insulation of the insulator Recently, it has been found by the present inventors that the performance of the present invention has been greatly reduced and the function as a cable required at the time of LOCA cannot be fulfilled because the prescribed pressure resistance test cannot be satisfied.

  Therefore, in the prior art, there is no material and technology that can be used as an internal insulator that has both high heat resistance and radiation resistance and electrical characteristics (electrical insulation), and has high heat resistance and radiation resistance. In addition, there has been a strong demand for a resin composition that can be used as a so-called internal insulator and that has both electrical characteristics (electrical insulating properties).

  The present invention has been made to solve the above-mentioned problems, and includes an insulator made of a composition that is applicable to a nuclear power plant, particularly a BWR containment vessel, and has excellent heat resistance, radiation resistance, and electrical characteristics. Another object is to provide a radiation-resistant insulated wire.

The present invention was invented in order to achieve the above object, a conductor, an insulating wire having an insulating layer covering directly above the conductor, said insulating layer, relative to 100 parts by weight of olefin polymers, aging It is a radiation resistant insulated wire containing 10 to 15 parts by mass of an inhibitor, 5 to 40 parts by mass of an aromatic process oil, and further containing 5 to 40 parts by mass of baked clay.

  The anti-aging agent is preferably composed of amine-based and sulfur-based anti-aging agents.

  The calcined clay is preferably surface-treated with organosilane.

  A flame retardant may be further added to 100 parts by mass of the olefin polymer.

The present invention devised to achieve the above object is a radiation-resistant insulated electric wire comprising a conductor and an insulating layer covering the periphery of the conductor, and the insulating layer is formed on 100 parts by mass of an olefin polymer. On the other hand, 10-15 parts by mass of an anti-aging agent, 5-40 parts by mass of aromatic process oil, further containing 5-40 parts by mass of calcined clay, and an internal insulating layer covering the top of the conductor ; It consists of a outer insulating layer covering a periphery of the inner insulating layer, the outer insulating layer, relative to 100 parts by weight of the olefin polymer, a radiation-resistant insulated wire you a flame retardant 20 parts by mass or more.

  ADVANTAGE OF THE INVENTION According to this invention, the radiation resistant insulated wire provided with the insulator which can be applied in the containment vessel of a nuclear power plant, especially BWR, and was excellent in heat resistance, radiation resistance, and an electrical property can be provided.

It is a figure explaining the test conditions of a LOCA simulation test.

  Hereinafter, a preferred embodiment of the present invention will be described.

  As a result of various studies to achieve the above-mentioned problems, 10 to 15 parts by weight of an antioxidant, 5 to 40 parts by weight of aromatic process oil, and 5 to 40 parts by weight of calcined clay are added to 100 parts by weight of an olefin polymer. It became clear that this would be possible.

  The cable is exposed to radiation (γ rays) and heat, and then exposed to high-temperature hot water by a LOCA simulation test. At this time, a material obtained by adding 10 to 15 parts by mass of an antioxidant, 5 to 40 parts by mass of an aromatic process oil, 20 parts by mass or more of a flame retardant, and 5 to 40 parts by mass of baked clay with respect to 100 parts by mass of an olefin polymer. By using it as an insulator, it can pass a withstand voltage test of electrical characteristics, exhibit excellent mechanical characteristics even after a LOCA simulation test, and can pass a severe flame retardant test.

  This is an ionic component that has been imparted with high radiation resistance and heat resistance with an anti-aging agent and aromatic process oil, while maintaining high flame resistance with a flame retardant, and they are altered or desorbed by radiation and heat. This is caused by suppressing the deterioration of the electrical characteristics by trapping the baked clay.

  Further, by subjecting the baked clay to surface treatment with organosilane (organosilane), the interaction between the polymer and the particles is enhanced, so that the ingress of moisture into the insulating layer can be suppressed and the electrical characteristics can be prevented from deteriorating.

  Below, each component used for an insulator is explained in full detail.

  Olefin polymers include polyethylene (PE) (low density polyethylene, medium density polyethylene, high density polyethylene, ultra-low density polyethylene, etc.), ethylene / vinyl acetate copolymer (EVA), and ethylene / methyl acrylate copolymer (EMA). , Ethylene / ethyl acrylate copolymer (EEA), natural rubber (NR), ethylene / propylene rubber (EPM), ethylene / propylene / diene terpolymer (EPDM), butyl rubber (IIR), nitrile rubber (NBR), non-halogen type Acrylic rubber (ACM), chlorinated polyethylene, chlorosulfonated polyethylene, epichlorohydrin rubber, acrylic rubber, halogenated butyl rubber and the like can be mentioned, and these can be used alone or in combination of two or more. These are all used after being crosslinked (vulcanized).

  In contrast to the above materials, anti-aging agents are generally used to maintain heat resistance, but also play an important role in radiation resistance. As types, there are phenol-based and amine-based primary anti-aging agents, and sulfur-based and phosphorus-based secondary anti-aging agents. Here, amine-based anti-aging agents and sulfur-based anti-aging agents are particularly effective, but other anti-aging agents may be used or used together. The total amount of both is required to be 10 parts by mass or more. Below this, the effects of radiation resistance and heat resistance are not sufficient. The upper limit is preferably up to about 15 parts by mass. Even if it is added more than this, the effect is saturated, and further, a substance having ionic conductivity is purified from the anti-aging agent, which is not a good idea because it adversely affects the electrical characteristics.

  Phenol-based antioxidants are classified into three types, monophenol, bisphenol and polyphenol, depending on the number of hydroxyl groups (—OH) present in the molecule.

  Monophenol includes 2,6-di-ter-butyl-4-methylphenol, 2,6-di-ter-butyl-4-ethylphenol, mono (α-methylbenzyl) phenol, and bisphenol includes 2 , 2′-methylenebis (4-methyl-6-ter-butylphenol), 2,2′-methylenebis (4-ethyl-6-ter-butylphenol), 4,4′-butylidenebis (3-methyl-6-ter-) Butylphenol), 4,4′-thiobis (3-methyl-6-ter-butylphenol), di (α-methylbenzyl) phenol, etc., and polyphenols include 2,5′-di-ter-butylhydroquinone, 2, 5′-di-ter-amylhydroquinone, tri (α-methylbenzyl) phenol, p-cresol and dicyclo Ntajien, and the like.

  Amine-based antioxidants are broadly classified into quinoline-based and aromatic secondary amines, and the former is 2,2,4-trimethyl-1,2-dihydroquinoline, 6-ethoxy-1,2-dihydro-2, 2,4-trimethylquinoline is exemplified. Examples of the latter include 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-dimethyl) Butyl) -p-phenylenediamine, N-phenyl-N ′-(3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine, and the like.

  Sulfur is classified into benzimidazole, dithiocarbamate, and thiourea, and benzimidazole includes 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, zinc salt of 2-mercaptobenzimidazole, and dithiocarbamic acid. Examples of the salt type include nickel diethyldithiocarbamate and nickel dibutyldithiocarbamate, and examples of the thiourea type include 1,3-bis (dimethylaminopropyl) -2-thiourea and tributylthiourea.

  The phosphorous system includes tris (norylphenyl) phosphite as the phosphorous acid system.

  Aromatic process oil is generally used as a compounding agent that stabilizes workability during kneading and extrusion, but is a mineral oil that is effective as a radiation resistance-imparting agent (anti-rad). Process oils are roughly classified into paraffinic, naphthenic, and aromatic types. In the present invention, those having an aromatic compound content of 20% or more in the Kurz analysis are used as aromatic process oils.

  If the amount of the aromatic process oil added is less than 5 parts by mass, the radiation resistance is not sufficient, and if it is more than 40 parts by mass, the effect is saturated, the flame retardancy is lowered, and the flame retardant test is passed. I can't. Further, when the polymer is crosslinked with a peroxide crosslinking agent, crosslinking is inhibited and the crosslinking cannot be performed sufficiently.

  A flame retardant is added to improve the flame retardancy of the polymer. Halogen flame retardants that can exhibit a high flame retardant effect without deteriorating mechanical properties with a small addition amount are desirable, but non-halogen flame retardants such as metal hydroxides such as aluminum hydroxide and magnesium hydroxide, phosphorus compounds, Commonly sold flame retardants such as nitrogen-containing compounds such as melamine, silicone compounds, calcium borate and zinc stannate may be used.

  Halogen flame retardants include ethylene bispentabromobenzene, tetrabromobisphenol, A-bis (2,3-dibromopropyl ether), decabromodiphenyl oxide, octabromodiphenyl oxide, pentabromodiphenyl oxide, tetrabromobisphenol A, tetra Bromobisphenol A-bis (allyl ether), tetrabromobisphenol A-bis (2-hydroxyether), hexabromocyclodecane, bis (tribromophenoxy) ethane, tetrabromobisphenol A epoxy oligomer, tetrabromobisphenol A carbonate oligomer, Ethylenebistetrabromophthalimide, poly-dibromophenylene oxide, 2,4,6-tribromophenol, tetrabromobispheno A-bis (acrylate), tetrabromophthalic anhydride, tetrabromophthalate diol, 2,3-dibromopropanol, tribromostyrene, tetrabromophenylmaleimide, poly (pentabromobenzyl) acrylate, tris (tribromoneopentyl) ) Phosphate, tris (dibromophenyl) phosphate, tris (tribromophenyl) phosphate, 1,2,3,4,7,8,9,10,13,13,14,14-dodecachloro-1,4,4a, 5,6,6a, 7,10,10a, 11,12,12a-dodecahydro-1,4,7,10-dimethanodibenzo (a, e) cyclooctene, chlorinated paraffin, perchlorocyclopentadecane, tetrachloroanhydrophthale Acid, chlorendic acid, dodecachlorosic Octane, and the like. If the amount added is less than 20 parts by mass, sufficient flame retardancy cannot be provided. Although there is no particular upper limit, it is preferably up to about 30 parts by weight considering the deterioration of electrical characteristics.

  It is known that a halogen-based flame retardant further exerts its effect when used in combination with a flame retardant auxiliary antimony trioxide, and the present invention is not an exception, and antimony trioxide may be added. The amount of addition is not particularly specified, but it is desirable to add at a ratio such that 1 atom of antimony is added to 3 atoms of halogen.

  Further, when a non-halogen flame retardant is used, it is preferably added in an amount of 80 parts by mass or more in order to impart sufficient flame retardancy. There is no particular upper limit, but considering the actual situation, the upper limit is preferably about 100 parts by mass.

  The calcined clay is mainly composed of hydrous aluminum silicate, calcined at an appropriate temperature (600 to 800 ° C.), released crystal water, collapsed crystal structure to enhance activity, and average by light scattering method or diffraction method. A particle size of 2.0 μm or less is used. Generally, it is added to prevent the appearance of the extruded product from deteriorating, but it can be expected to adsorb an ion conductive substance and improve the electrical characteristics. If the addition amount is less than 5 parts by mass, the ion conductive material generated from the halogen-based flame retardant or anti-aging agent cannot be sufficiently captured. If the addition amount exceeds 40 parts by mass, the calcined clay and polymer / calcined clay It easily attracts moisture to the interface, and conversely deteriorates electrical characteristics.

  Further, when exposed to high-temperature and high-pressure steam as in the LOCA simulation test, moisture easily penetrates into the polymer / fired clay interface, and therefore the fired clay is preferably surface-treated with organosilane. The surface treatment with organosilane prevents aggregation of the fired clay, improves dispersibility in the polymer, and improves the adhesion between the polymer and the fired clay.

  Examples of the organosilane include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3- (2aminoethyl) aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropylmethyldimethoxysilane, 3-phenylaminopropyltrimethoxysilane, N- (p-vinylbenzyl) -N- (trimethoxysilylpropyl) ethylenediamine hydrochloride, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane 3-glyoxydoxypropyltriethoxysilane, 3-glyoxydoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, bis (3- (triethoxysilyl) propyl) disulfide, bi (3- (triethoxysilyl) propyl) tetrasulfide, vinyltriacetoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, allyltrimethoxysilane, diallyldimethoxysilane, 3-methacryloxypropyltrimethoxy Silane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltriethoxysilane, N- (1,3 -Dimethylbutylidene) silane coupling agents such as 3-aminopropyltriethoxysilane, alkoxysilanes, vinylmethylsiloxane-dimethylsiloxane copolymers, trimethyl Such a siloxane oligomer such as siloxy derivative can be mentioned, handling, from the viewpoint of price, 3-glycidoxypropyltrimethoxysilane, dimethylsulfoxide trimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, siloxane oligomer are preferred.

  Further, the surface treatment amount is preferably 0.5 mass% or more and not exceeding 3 mass% (0.5 mass% or more and less than 3.0 mass%), and if it is less than that, sufficient effects cannot be obtained, and if it is more than that, electric insulation characteristics May adversely affect Organosilane may be a method in which the inorganic filler is treated in advance, or an integral blend method in which it is directly added to the resin and the inorganic filler and kneaded.

  The method of crosslinking and vulcanization is not particularly specified, but peroxide crosslinking excellent in heat resistance and radiation resistance is desirable, and triallyl cyanurate (TAC), triallyl isocyanurate ( A crosslinking aid such as a polyfunctional monomer such as TAIC) or trimethylolpropane trimethacrylate (TMPT) may be used in combination.

  In addition, compounding agents such as lubricants, processing aids, fillers, colorants, light stabilizers (such as hindered amine light stabilizers), and UV absorbers added to general rubber materials, as long as the effects of the present invention are not impaired. Various types can be used.

  Examples of the chlorinated polymer applied to the sheath material include polychloroprene rubber, chlorosulfonated polyethylene, and chlorinated polyethylene, which can be used alone or in combination of two or more. Moreover, a chlorine polymer and the said olefin polymer can be blended and used. The sheath material is also used after being crosslinked (vulcanized) like the insulator.

  The sheath material also contains process oil, lubricant, processing aid, filler, colorant, light stabilizer, UV absorber, etc. containing anti-aging agent, heat stabilizer, and radiation resistance imparting agent as well as insulator material. Various agents can be used.

  As described above, in the radiation-resistant insulated wire of the present invention, the insulating layer covering the periphery of the conductor is 10 to 15 parts by mass of the anti-aging agent, 100 parts by mass of the olefin polymer, and aromatic process oil. In an amount of 5 to 40 parts by mass, and further contains 5 to 40 parts by mass of calcined clay.

  As a result, the anti-aging agent and the aromatic process oil provide high radiation resistance and heat resistance, while maintaining high flame resistance with the flame retardant, they are altered or desorbed by radiation and heat. It is possible to suppress a decrease in electrical characteristics by trapping the fired clay.

  The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the technical idea of the present invention.

  For example, in the radiation-resistant insulated wire of the present invention, as another embodiment, the electrical characteristics of the wire / cable can be further improved by making the insulator a two-layer structure.

  That is, 10-15 parts by mass of an anti-aging agent, 5-40 parts by mass of aromatic process oil, and 5-40 parts by mass of calcined clay are added to 100 parts by mass of the olefin polymer. In addition to being used for the inner insulation layer), and for the outer layer (outer insulation layer), by using a resin composition in which 20 parts by mass or more of a flame retardant is further added to the above composition, it is difficult for the radiation resistant insulated wire. While maintaining the flammability, the electrical properties can be improved as much as no flame retardant is added to the resin composition used for the internal insulator.

  Examples of the present invention and comparative examples will be described below.

  Insulator materials shown in Tables 1 and 2 and various compounding agents of the sheath material shown in Table 3 were weighed, and after removing the cross-linking agent, they were put into a 75 liter Banbury mixer and kneaded, and the resulting 1st compound had about 60 A cross-linking agent was added and mixed in a 50 liter kneader maintained at ° C. to obtain a 2nd compound (in Tables 1 and 2, silane-treated calcined clay represents a calcined clay surface-treated with organosilane).

Each of the insulator materials shown in Table 1 and Table 2 is extruded and coated at a thickness of 0.8 mm onto a conductor having a conductor cross-sectional area of 2.0 mm ² , crosslinked with high-pressure steam at about 190 ° C., and then twisted. A sheath material was extruded and coated around the combined cores with an extruder, and then cross-linked with a pressurized salt (molten salt) at about 200 ° C. to obtain a cable having an outer diameter of 10.5 mmφ.

  Table 4 shows the details of the produced cables.

  As shown in Table 4, Examples 1 to 6 were cables using the materials shown in Tables 1 and I to VI of the insulator A as insulating layers.

  Moreover, the cable which used the material shown to Table 2, I-VII of the insulator B for the insulating layer was made into Comparative Examples 1-7.

  The obtained cable was subjected to a test on the following items and evaluated comprehensively.

(1) Flame retardancy test:
A vertical tray combustion test was performed and evaluated based on IEEE Std 1202-1991. Three cables with a length of 2.4 m were bundled into one bundle and installed on 8 vertical trays. The test was conducted, and a fire spread distance (blur) of 150 cm or less was accepted.

(2) LOCA simulation test:
A LOCA simulation test sample was prepared using a cable of about 10 m in length under the following conditions. ^A high pressure steam exposure test was carried out under the LOCA simulation test conditions shown in FIG. 1 on a sample that had been heat aged at 140 ° C. for 9 days after irradiation with 1 MGy at a dose rate of 5 kGy / h with ⁶⁰ Co · γ rays. After that, it is wound around a mandrel 40 times the outer diameter of the cable, and the parts other than both ends are left in room temperature water for 1 hour, and then the insulation resistance is measured with an insulation resistance meter (Megger). The one that was able to be held without being broken was regarded as acceptable.

  Further, after the withstand voltage test, a sound portion of the cable was collected in appearance, and a tensile test was performed with a tensile tester based on JISC3005 to evaluate the elongation at break.

  The above test results were comprehensively judged, and pass / fail was determined.

  Table 5 shows the cable evaluation results.

  As shown in Table 5, Examples 1 to 6 of the present invention satisfied all the characteristics and the overall judgment was acceptable.

  On the other hand, in Comparative Example, Comparative Example 1 with a small amount of anti-aging agent was remarkably deteriorated due to gamma ray exposure and thermal deterioration, the electrical characteristics deteriorated, and the LOCA simulation test could not be passed. In Comparative Example 2, the amount of the anti-aging agent was large, and the ionic component increased due to γ rays and thermal deterioration, which deteriorated the electrical characteristics. Therefore, the LOCA simulation test could not be passed. Comparative Example 3 with a small amount of aromatic process oil added was inferior in radiation resistance and deteriorated significantly by gamma rays, and failed to pass the LOCA simulation test. Moreover, although the comparative example 4 with much addition amount of an aromatic process oil can pass a LOCA simulation test, the flame retardance failed. The comparative example 5 with a small amount of flame retardant added also failed in the flame retardancy test. Comparative Example 6 with a small amount of added clay had poor electrical properties and failed the LOCA simulation test. This is considered due to the fact that the ion conductive component could not be captured. In Comparative Example 7 in which the amount of calcined clay added was large, the electrical characteristics deteriorated and the LOCA simulation test could not be passed.

Claims (5)

And the conductor, an insulating wire having an insulating layer covering directly above the conductor,
The insulating layer contains 10 to 15 parts by mass of an antioxidant, 5 to 40 parts by mass of aromatic process oil, and further contains 5 to 40 parts by mass of calcined clay with respect to 100 parts by mass of the olefin polymer. A radiation-resistant insulated wire characterized by   The radiation-resistant insulated wire according to claim 1, wherein the anti-aging agent comprises an amine-based and sulfur-based anti-aging agent.   The radiation-resistant insulated electric wire according to claim 1 or 2, wherein the fired clay is surface-treated with an organosilane.   The radiation-resistant insulated wire according to any one of claims 1 to 3, wherein a flame retardant is further added to 100 parts by mass of the olefin polymer. A radiation-resistant insulated electric wire having a conductor and an insulating layer covering the conductor,
The insulating layer contains 10 to 15 parts by weight of an antioxidant, 5 to 40 parts by weight of an aromatic process oil, and further contains 5 to 40 parts by weight of calcined clay, based on 100 parts by weight of an olefin polymer. An internal insulating layer covering directly above the conductor;
It consists of a outer insulating layer covering a periphery of the inner insulating layer,
The outer insulating layer, relative to 100 parts by weight of olefin polymers, radiation resistant insulated wire, characterized in that it contains a flame retardant 20 parts by mass or more.

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