JP2016003321A - Radiation-resistant resin composition, radiation-resistant cable using the same, and method for manufacturing the cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation-resistant resin composition having radiation resistance at a high level, exhibiting good mechanical characteristics such as tensile strength without using lead oxide and further without lead vulcanization, and capable of suppressing deformation during vulcanization, and a radiation-resistant cable using the composition, and a method for manufacturing the radiation-resistant cable.SOLUTION: A radiation-resistant cable 20 is manufactured by applying and vulcanizing the following radiation-resistant resin composition around twisted electric wires formed by twisting a plurality of conductors 1 coated with an insulator 2. The radiation-resistant resin composition comprises a chlorosulfonated polyethylene, an aromatic process oil, magnesium oxide, hydrotalcite, and carbon black having a dibutyl phthalate oil absorption of 100 ml/100 g or more, in which the carbon black is included by 50 to 100 pts.mass with respect to 100 pts.mass of the chlorosulfonated polyethylene.

Description

  The present invention relates to a radiation-resistant resin composition, a radiation-resistant cable using the same, and a method for producing the same, particularly in a nuclear power facility where a region having a very high radiation field exists in a radiation environment. The present invention relates to a radiation resistant resin composition for cables used, a radiation resistant cable using the same, and a method for producing the same.

  In nuclear power plants, fast breeder reactors, nuclear fuel reprocessing facilities, particle accelerator facilities, etc., radiation such as γ rays exists in the usage environment. For this reason, electric wires and cables used for power supply and signal transmission to each facility / equipment are required to withstand deterioration due to radiation.

  Examples of such wire / cable coating materials that require radiation resistance include resin compositions such as ethylene propylene rubber, polychloroprene rubber, and chlorosulfonated polyethylene, and aromatic process as a radiation resistance-imparting agent. It is known to add oil.

  Of these, chlorosulfonated polyethylene is often used as a sheath material because it does not contain unsaturated double bonds in the structure, contains halogen, and has high mechanical properties such as tensile strength. In addition, it is known to use metal oxides such as lead oxide, magnesium oxide and hydrotalcite as an acid acceptor for vulcanizing chlorosulfonated polyethylene.

  For example, Patent Document 1 discloses a chlorosulfonated polyethylene composition in which lead oxide, an organic layered clay mineral, and carbon black are added to chlorosulfonated polyethylene, which is excellent in lead vulcanization processability and the like. Have been described.

  Patent Document 2 discloses a radiation resistant electric wire / cable insulation composition obtained by adding 20 to 80 parts by weight of aromatic oil having an aromatic amount of 30 WT% or more to 100 parts by weight of alkylated chlorosulfonated polyethylene. It is described that PbO is used as a crosslinking agent.

  Patent Document 3 discloses a polymer containing no chlorine as a crosslinking agent and containing chlorine such as chlorosulfonated polyethylene, a layered inorganic compound such as a hydrotalcite compound, a flame retardant, a processing aid, and aging. A radiation resistant cable comprising an inhibitor is disclosed.

JP 2012-87224 A Japanese Patent No. 3178265 JP 2010-27291 A

  However, in patent document 1, since lead oxide is used as an acid acceptor, it is not preferable for environmental hygiene at the cable manufacturing site. Further, since lead vulcanization is performed, there is a high possibility that a lead compound remains on the cable surface, and when the cable is discarded, the lead compound may be eluted, which is not preferable. Therefore, it is desirable to vulcanize without using lead oxide and without further covering with lead, but problems such as deterioration of mechanical properties such as tensile strength and loss of shape during vulcanization occur. In Patent Document 1, the radiation resistance is about 2 MGy and there is room for improvement.

  In Patent Document 2, the radiation resistance is 10 MGy, but PbO is used in Patent Document 2 as well, so that there is the same problem as Patent Document 1.

  In Patent Document 3, there is room for improvement in that radiation resistance is about 2 MGy, as in Patent Document 1. In addition, when the cross-sectional area of the electric wire / cable (cable outer diameter) becomes large, it is necessary to carry out lead vulcanization. However, if lead vulcanization is carried out, the same problem as in Patent Document 1 occurs. To do.

  Therefore, the object of the present invention is to have a high radiation resistance and to have good mechanical properties such as tensile strength without using lead oxide and without lead vulcanization, and lose shape during vulcanization. It is in providing the radiation-resistant resin composition which can suppress, a radiation-resistant cable using the same, and its manufacturing method.

  In order to achieve the above object, the present invention provides the following radiation resistant resin composition, a radiation resistant cable using the same, and a method for producing the same.

[1] Chlorosulfonated polyethylene, aromatic process oil, magnesium oxide, hydrotalcite, and carbon black having a dibutyl phthalate oil absorption of 100 ml / 100 g or more, and with respect to 100 parts by mass of the chlorosulfonated polyethylene, the carbon A radiation resistant resin composition comprising 50 to 100 parts by mass of black.
[2] The radiation resistance according to [1], comprising 20 to 80 parts by mass of the aromatic process oil and 10 to 30 parts by mass of the magnesium oxide with respect to 100 parts by mass of the chlorosulfonated polyethylene. Resin composition.
[3] The periphery of a twisted electric wire formed by twisting a plurality of conductors coated with an insulator is coated with the radiation-resistant resin composition according to [1] or [2] and vulcanized. A radiation resistant cable characterized by that.
[4] The radiation-resistant cable according to [3], wherein the insulator includes polyether ether ketone (PEEK).
[5] The radiation-resistant cable described in [3] or [4] is covered with the radiation-resistant resin composition described in [1] or [2] and vulcanized. Flat type radiation resistant cable.
[6] A method for manufacturing a radiation-resistant cable according to [3] or [4], wherein the method includes the step of performing the vulcanization without being covered with lead. Method.
[7] The periphery of the radiation resistant cable produced by the method for producing a radiation resistant cable according to [6] is coated with the radiation resistant resin composition according to [1] or [2], A method for producing a flat radiation-resistant cable, which comprises a step of vulcanizing without leading.

  According to the present invention, it has a high level of radiation resistance and has excellent mechanical properties such as tensile strength without using lead oxide and without lead vulcanization, and suppresses deformation during vulcanization. A radiation-resistant resin composition that can be produced, a radiation-resistant cable using the same, and a method for producing the same can be provided.

It is a cross-sectional view which shows an example of the cable used for the cable (FIG. 2) which concerns on embodiment of this invention. It is a cross-sectional view showing an example of a cable according to an embodiment of the present invention. It is a cross-sectional view showing an example of a flat cable according to an embodiment of the present invention. It is the schematic which shows the bending test method performed for evaluation of a radiation resistance in an Example. It is the schematic which shows the ironing test method performed for evaluation of radiation resistance in an Example.

[Radiation resistant resin composition]
The radiation-resistant resin composition according to the embodiment of the present invention includes chlorosulfonated polyethylene, aromatic process oil, magnesium oxide, hydrotalcite, and carbon black having a dibutyl phthalate oil absorption of 100 ml / 100 g or more, The carbon black is contained in an amount of 50 to 100 parts by mass with respect to 100 parts by mass of the chlorosulfonated polyethylene.

(Chlorosulfonated polyethylene)
The radiation resistant resin composition according to the embodiment of the present invention contains chlorosulfonated polyethylene as a base polymer.

  The chlorosulfonated polyethylene used in the present embodiment is not particularly limited, and those generally used industrially can be used. An alkylated chlorosulfonated polyethylene in which an alkyl chain is introduced into the side chain of chlorosulfonated polyethylene may be used.

  The chlorosulfonated polyethylene preferably has a chlorine content of about 25 to 45% by mass and a sulfur content of about 0.7 to 1.5% by mass. This is because the chlorine content for the chlorosulfonated polyethylene to have good rubber elasticity is within the above range, and the sulfur content having appropriate vulcanization characteristics is within the above range.

  The molecular weight of the chlorosulfonated polyethylene is not particularly limited, but since an aromatic process oil is added to impart radiation resistance, an L-shaped rotor is used for the purpose of maintaining thermal deformability and mechanical properties. After preheating at 100 ° C. for 1 minute, it is preferable to use one having a Mooney viscosity of 90 or more after 4 minutes.

  Two or more types of chlorosulfonated polyethylene may be blended as required. Moreover, as long as the effect of this invention is show | played, you may add another polymer as needed.

(Aromatic process oil)
The radiation resistant resin composition according to the embodiment of the present invention contains an aromatic process oil.

  As the aromatic process oil used in the present embodiment, an aromatic process oil that is industrially used for general rubber can be used. In the present embodiment, the amount of the aromatic compound in the aromatic process oil is preferably 25% by mass or more in Kurz analysis based on ASTM D2140.

  Aromatic process oils are used as radiation resistance-imparting agents because they contain many compounds containing a benzene ring as well as processing aids that are their original purpose. For this reason, it is preferable that the aromatic compound content is large. However, since aromatic process oils are known to contain a large amount of polycyclic aromatic compounds that are considered to be highly carcinogenic, 3-7 ring polycyclic aromatic compounds extracted with dimethyl sulfoxide are used. It is desirable to use TDAE (Treated Distillate Aromatic Extracts) adjusted to 3% or less.

  The addition amount of the aromatic process oil is preferably 20 to 80 parts by mass with respect to 100 parts by mass of chlorosulfonated polyethylene. It is more preferably 30 to 70 parts by mass, and further preferably 40 to 60 parts by mass. This is because if the amount is less than 20 parts by mass, the resin composition may deteriorate and become brittle depending on the dose of radiation resistance. In addition, if it exceeds 80 parts by mass, aromatic process oil may bleed out from the vulcanized resin composition, and if the amount of oil added is large, the viscosity of the material may not increase and kneading may not be successful. Because.

(Magnesium oxide)
The radiation resistant resin composition according to the embodiment of the present invention contains magnesium oxide.

  The magnesium oxide used in the present embodiment is not particularly limited as long as it is generally used industrially. By using highly active magnesium oxide fired at a low temperature, a resin composition having a high vulcanization speed and a high vulcanization density can be obtained. Moreover, in order to improve the dispersibility of magnesium oxide, magnesium oxide surface-treated with a higher fatty acid can be used.

  Magnesium oxide acts as an acid acceptor and vulcanizing agent for chlorosulfonated polyethylene. Hydrotalcite, which will be described later, is an additive that has the same effect, but hydrotalcite has a weaker action than magnesium oxide, and when used together with magnesium oxide, the vulcanization speed is high and the resin composition has a high vulcanization density. You can get things.

  The amount of magnesium oxide added is preferably 10 to 30 parts by mass with respect to 100 parts by mass of chlorosulfonated polyethylene. It is more preferably 10 to 25 parts by mass, and further preferably 10 to 20 parts by mass. If it is 10 parts by mass or less, the vulcanization speed is slow and the vulcanization time needs to be set long. Furthermore, moisture adhering to carbon black described later and hydrogen chloride gas generated from chlorosulfonated polyethylene cannot be efficiently captured, and the resin composition may become a foam depending on the vulcanization temperature. On the other hand, when the amount exceeds 30 parts by mass, the vulcanization speed becomes high, so that scorching is likely to occur during extrusion molding, and setting of molding conditions becomes difficult. Further, the amount of magnesium chloride produced by reaction with the hydrogen chloride gas increases, and the magnesium chloride is easily dissolved in water, so that the resin composition is not excellent in water resistance.

(Hydrotalcite)
The radiation resistant resin composition according to the embodiment of the present invention contains hydrotalcite.

The hydrotalcite used in the present embodiment can be an industrially used one, regardless of whether it is a natural mineral or a synthetic product. Hydrotalcite is a compound represented by the general formula [M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] [A ^n- _{x / n} · mH ₂ O], where M ²⁺ and M ³⁺ are Divalent and trivalent metal ions are represented, and A ⁿ _{-x / n} represents an interlayer anion. In the present embodiment, it is preferable to use hydrotalcite in which M ²⁺ is Mg ²⁺ , M ³⁺ is Al ³⁺ , and ^Anx _{/ n} is CO ₃ ^2- .

  Hydrotalcite acts as an acid acceptor because the carbonate ions between the layers are replaced by chlorine ions and incorporated into the crystal structure. As described above, it becomes an auxiliary acid acceptor for magnesium oxide, and even when chlorine in chlorosulfonated polyethylene is desorbed as hydrogen chloride, it can capture chlorine ions and prevent continuous deterioration. Furthermore, the solubility of the hydrotalcite compound capturing chlorine ions in water is low, and when used together with magnesium oxide, a resin composition having excellent water resistance can be obtained.

  The amount of hydrotalcite added is preferably 3 to 30 parts by mass with respect to 100 parts by mass of chlorosulfonated polyethylene. It is more preferably 5 to 25 parts by mass, and further preferably 5 to 20 parts by mass.

(Carbon black)
The radiation resistant resin composition according to the embodiment of the present invention contains carbon black.

  Carbon black used in the present embodiment has a dibutyl phthalate oil absorption amount (hereinafter referred to as DBP oil absorption amount) of 100 ml / 100 g or more as defined in JIS K 6217 Part 4 Determination of carbon black oil absorption amount for rubber. Must. The DBP oil absorption is known to represent the size of secondary aggregates (aggregates) of carbon black. A large DBP oil absorption suggests that the aggregate is large.

  As described above, the present invention is a radiation resistant resin composition obtained by adding an aromatic process oil to chlorosulfonated polyethylene. When this resin composition is used as a cable coating material, lead vulcanization is necessary to prevent deformation during vulcanization when the outer diameter of the cable is increased to some extent (50 mm or more). For this reason, as a result of various studies, the aggregate of carbon black added to chlorosulfonated polyethylene is large (DBP oil absorption is 100 ml / 100 g or more), and the carbon black is 50 parts per 100 parts by mass of chlorosulfonated polyethylene. If -100 parts by mass is added, a flat cable (described later) can be obtained by coating and vulcanizing a hard polymer (eg, polymethylpentene) having a high crystalline melting point instead of lead, without vulcanizing the lead. In some cases, it has been found that a radiation-resistant resin composition capable of suppressing deformation (deformation) during vulcanization can be obtained without coating anything.

  In general, carbon black is known as an additive capable of increasing the strength of vulcanized and unvulcanized rubber. It is known that if the particle size of the carbon black is finer, the reinforcement becomes higher. However, when ensuring the reinforcement of the unvulcanized rubber, the DBP oil absorption amount and the size of the aggregate are larger than the particle size of the carbon black. It turns out that it depends on. That is, if the aggregate is small even if the particle size of carbon black is small (for example, Tokai Carbon Seast 300, average particle size: 28 nm, DBP oil absorption: 75 ml / 100 g), the reinforcing property given to unvulcanized rubber is not large. It was found that it was easily deformed during vulcanization. On the other hand, when carbon black having a relatively large particle diameter but a large DBP oil absorption (for example, Asahi Carbon 60 manufactured by Asahi Carbon, average particle diameter: 45 nm, DBP oil absorption: 114 ml / 100 g) is used. It was found that the deformation in the sulfur was small. The vulcanization temperature is about 150 ° C.

  The large aggregate not only gives reinforcing properties to the unvulcanized rubber, but also serves to immobilize the radiation resistance-imparting agent. In the present invention, an aromatic process oil is added in order to impart a high level of radiation resistance. However, if this aromatic process oil has a large DBP oil absorption amount, it is easily incorporated into carbon black, and the unvulcanized rubber It has been found that the adhesiveness is reduced, the kneading processability and the extrusion processability are improved, and a resin composition having a small variation in characteristics can be produced.

  Carbon black, which has a large DBP oil absorption and a large aggregate, has a large amount of adhering moisture and is known as a cause of foaming of the resin composition. However, as in the present invention, magnesium oxide is used by using magnesium oxide as the acid acceptor. It was found that foaming can be suppressed by reacting with adhering moisture in carbon black. Calcium oxide is well known as a foaming inhibitor and water-removing agent for resin compositions. On the other hand, since chlorosulfonated polyethylene requires water for the vulcanization reaction, if a water-absorbing agent having a large effect such as calcium oxide is used, the water necessary for vulcanization is deprived from the resin composition. End up. For this reason, it turned out that it acts moderately as a foaming inhibitor and can suppress foaming by adding magnesium oxide as an acid acceptor as in the present invention.

  If the added amount of carbon black having a DBP oil absorption of 100 ml / 100 g or less is less than 50 parts by mass with respect to 100 parts by mass of chlorosulfonated polyethylene, deformation occurs during vulcanization, and if it exceeds 100 parts by mass, the rubber becomes hard. As a result, the initial tensile elongation is remarkably deteriorated.

(Other additives)
In addition to the above components, the radiation-resistant resin composition according to the embodiment of the present invention includes a flame retardant, an antioxidant, a vulcanization accelerator, as necessary, within a range that does not impair the effects of the present invention. Lubricants, fillers, softeners, ultraviolet absorbers and the like can be used as appropriate.

  Examples of flame retardants include brominated flame retardants such as antimony trioxide, decabromodiphenylethane and ethylenebistetrabromophthalimide, chlorinated flame retardants such as decachloro, dodecahydro, dimethano, cyclooctene and chlorinated paraffin, magnesium hydroxide and Metal hydrates such as aluminum hydroxide, nitrogen compound flame retardants such as melamine / cyanurate mixture, zinc flame retardants such as zinc borate and zinc phosphate, phosphorus flame retardants, silicates such as glass frit and amorphous silica Examples include flame retardants. In the embodiment of the present invention, a chlorine-based flame retardant or a brominated flame retardant and a combination of antimony trioxide are preferable from the viewpoint of mechanical properties and compatibility with chlorosulfonated polyethylene.

  Examples of the antioxidant include phenol-based and amine-based primary antioxidants and sulfur-based or phosphorus-based secondary antioxidants.

  Phenol-based primary antioxidants are classified into monophenol-based, bisphenol-based, and polyphenol-based. Monophenols include 2,2'-di-t-butyl-4-methylphenol, 2,6-di-t-butyl-4-ethylphenol, mono (α-methylbenzyl), bisphenol 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6 -t-butylphenol, 4,4'-tibis (3-methyl-6-t-butylphenol), butylated product of p-cresol and dicyclopentadiene, di (α-methylbenzyl), etc. 2,5′-di-t-butylhydroquinone, 2,5′-di-t-amylhydroquinone, tri (α-methylbenzyl) and the like.

  Examples of amine-based primary antioxidants include 2,2,4-trimethyl-1,2-dihydroquinoline, 6-ethoxy-1.2-dihydro-2.2.4-trimethylquinoline, phenyl-1-naphthylamine, and alkylation. 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 and the like.

  Examples of sulfur-based secondary antioxidants include 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, zinc salt of 2-mercaptobenzimidazole, nickel diethyldithiocarbamate, nickel dibutyldithiocarbamate, 1,3-bis ( Dimethylaminopropyl) -2-thiourea, tributylthiourea, dilauryl thiodipropionate, and the like.

  Phosphorus secondary antioxidants include tris (nonylphenyl) phosphite as the phosphorous acid system.

  Also, a mixed product obtained by mixing a plurality of the above-mentioned antioxidants into one pack can be used. In the embodiment of the present invention, the combined use of an amine-based primary antioxidant and a sulfur-based secondary antioxidant is preferable, and in particular, the combined use of alkylated diphenylamine and nickel dibutyldithiocarbamate is effective for radiation resistance. high.

  As a vulcanization accelerator, a vulcanization accelerator used for general rubber can be used. In the present invention using chlorosulfonated polyethylene, a thiazole accelerator and a thiuram accelerator are used in combination. It is preferable.

  As the lubricant, for example, wax is preferably used.

[Radiation resistant cable]
The radiation-resistant cable according to the embodiment of the present invention is the radiation-resistant resin composition according to the embodiment of the present invention around the stranded wire formed by twisting a plurality of conductors coated with an insulator. It is characterized by being coated and vulcanized.

  FIG. 1 is a cross-sectional view showing an example of a cable used for a cable (FIG. 2) according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing an example of a cable according to an embodiment of the present invention. FIG.

  The configuration of the cable 10 shown in FIG. 1 will be described in detail in an embodiment described later, but is not limited thereto, and various configurations can be adopted. In FIG. 1, four conductors 1 covered with the insulator 2 are used, but may be 1 to 3 conductors or 5 or more conductors. The insulator 2 may have a single layer structure or a multilayer structure. The suf yarn 3, PET tape 4, metal braid 5, rubberized cloth tape 6 and the like shown in FIG. 1 can be provided as necessary.

  Although various resin compositions can be used for the insulator 2, it is preferable to use one containing polyether ether ketone (PEEK). By using polyether ether ketone (PEEK) containing an aromatic ring in the polymer main chain having excellent radiation resistance as the cable insulator material, a cable that can be used even in a place that can move in a very high level radiation field is obtained. be able to.

  The configuration of the cable 20 shown in FIG. 2 will also be described in detail in an embodiment described later, but is not limited thereto, and various configurations can be adopted.

  The periphery of a twisted wire formed by twisting a plurality of cables 10 including the conductor 1 coated with the insulator 2 is covered with the radiation-resistant resin composition according to the embodiment of the present invention, and vulcanized. Thus, the cable 20 is obtained. In FIG. 2, although 11 + 18 = 29 cables 10 are twisted together, the present invention is not limited to this.

  As a coating method and a crosslinking method of the radiation resistant resin composition, conventionally known methods can be used, and there is no particular limitation. However, by using the radiation-resistant resin composition of the present invention, cables that have a particularly large outer diameter (50 mm or more) and flat-shaped cables are less likely to lose shape without being lead-cured. Therefore, it is desirable to vulcanize without covering the outer periphery of the coated radiation-resistant resin composition 14 in the crosslinking step.

[Flat type radiation resistant cable]
The flat radiation-resistant cable according to the embodiment of the present invention is obtained by coating the periphery of the radiation-resistant cable according to the embodiment of the present invention with the radiation-resistant resin composition according to the embodiment of the present invention. It is characterized by being vulcanized.

  FIG. 3 is a cross-sectional view showing an example of a flat cable according to an embodiment of the present invention.

  Although FIG. 3 shows an example in which two radiation-resistant cables 20 are arranged in parallel, three or more cables may be used.

  As a coating method and a crosslinking method of the radiation resistant resin composition, conventionally known methods can be used, and there is no particular limitation. However, by using the radiation-resistant resin composition of the present invention, cables that have a particularly large outer diameter (50 mm or more) and flat-shaped cables are less likely to lose shape without being lead-cured. Therefore, it is desirable to vulcanize without covering the outer periphery of the coated radiation-resistant resin composition 22 in the crosslinking step.

  Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited thereto.

  A cable having the structure shown in FIGS. 1 to 3 was manufactured and evaluated by the following method.

The insulation 2 is coated by extruding polyether ether ketone (PEEK) with a thickness of 0.2 mm on a tin-plated copper conductor 1 having a cross-sectional area of 2 mm ² obtained by twisting a plurality of strands. A PEEK electric wire having a diameter of 2.2 mm was produced.

  Four obtained PEEK electric wires and the staple yarn 3 are twisted together, a polyethylene terephthalate (PET) tape 4 having a thickness of 0.04 mm and a width of 20 mm is wound around the PEEK wire, and a metal braiding with a tin-plated copper conductor on the PET tape 4 5 and a rubber braided tape 6 having a thickness of 0.1 mm was further wound on the metal braid 5 to obtain a cable 10 having an outer diameter of 6.4 mm and a cross section shown in FIG.

Eleven cables 10 are arranged and twisted on a string of outer diameter 16.8 mm, which is obtained by knitting polyarylate fibers on a rope 11 and covering an unvulcanized rubber 12 with a thickness of 3.4 mm. The jute 13 was arranged as an interposition on 10, and 18 cables 10 were further arranged on the jute 13 and twisted together. The resin composition 14 shown in Tables 1 and 2 is extruded at a thickness (t _{1 in} FIG. 2) of 2.55 mm immediately above the 18 cables 10 twisted together, the outer diameter is 48.4 mm, and the cross section is shown in FIG. A cable 20 (small unit) having the structure shown was obtained. Polymethylpentene resin is extrusion coated on a small unit, heated with saturated steam at 145 ° C. for 45 minutes, peeled off, and coated with vulcanized resin composition 14 shown in Table 1 and Table 2. Cable 20 (small unit) was obtained.

  As an indicator of loss of shape during vulcanization, the thickness of the resin composition 14 coated with a thickness of 2.55 mm is less than 2 mm when the polymethylpentene resin is peeled off after vulcanization. Those that did not pass were accepted. The evaluation results are shown in Tables 1 and 2.

  At this time, those that were out of shape (Comparative Examples 2 to 4 and 6) were subjected to lead vulcanization, and those that were not out of shape were produced again and sent to the next step.

A general fabric 21 having a thickness of 0.5 mm is wound around the vulcanized cable 20 (small unit), and the two cables 20 (small units) are arranged side by side, with a short diameter (L _{1 in} FIG. 3) of 56.5 mm and a long diameter. (L _{2 in} FIG. 3) The resin composition 22 shown in Tables 1 and 2 was extrusion-coated at a thickness (t _{2 in} FIG. 3) of 3.5 mm so as to be 105.85 mm, and the unvulcanized state Was wound on a drum and heated with saturated steam at 145 ° C. for 45 minutes to vulcanize the resin composition 22 to obtain a flat cable 30 having a cross section shown in FIG.

  As an index of loss of shape during vulcanization, a resin composition 22 coated with a thickness of 3.5 mm that had a partial minimum thickness not less than 2.8 mm after vulcanization was regarded as acceptable. Moreover, it rejected about what a foam is seen in a cross section. The evaluation results are shown in Tables 1 and 2.

  About the produced flat cable 30, the tension test and the radiation resistance test were done by the method shown below.

(1) Tensile test The sheath material (resin composition 22) of the produced flat cable 30 was peeled off, and a tensile test was performed according to JIS C 3005. The shape was a JIS No. 3 dumbbell and the tensile speed was 500 mm / min. Those having a tensile strength of 13 MPa or more and a breaking elongation of 300% or more were regarded as acceptable. The evaluation results are shown in Tables 1 and 2.

(2) Radiation resistance test The produced flat cable 30 was irradiated with γ rays up to 4 MGy at room temperature and atmospheric pressure at a dose rate of about 5 kGy / h using a Co60 radiation source. After the irradiation, the bending test shown in FIG. 4 and the ironing test shown in FIG. The evaluation results are shown in Tables 1 and 2.

<Bending test>
FIG. 4 is a schematic diagram showing a bending test method performed for evaluating radiation resistance.
One end of the flat cable 30 (cable sample) is fixed to the fixing plate 42, a load is applied to the other end in the downward direction in FIG. 4, and the cable is bent 90 degrees left and right at the position of the fixing pulley 41. The number of tests is counted as one cycle of “I → II → III → IV” in FIG.
Cable sample length: 2.5m
Bending radius: 250mm
Load: Minimum number of load tests that can be performed: 1000 times

<Squeeze test>
FIG. 5 is a schematic view showing an ironing test method performed for evaluating radiation resistance.
By connecting the flat cable 30 (cable sample) with the wire rope 54 at the connection portion 55, the flat cable 30 is connected to the rotation drive portion 53, which is a power source, via the wire rope 54. While the tension is applied to the flat cable 30 in the left direction in FIG. 5, the rotation driving unit 53 is operated, and the flat cable 30 is moved horizontally in contact with the pulley 52 fixed to the pulley fixing plate 51. The number of tests is counted as one horizontal movement in one reciprocating direction in the movable direction shown in FIG.
Cable sample length: 8.0m
Movable stroke: 2.3m
Pulley diameter: 750mm
Tension: 100kgf
Number of tests: 1000 times

(3) Comprehensive judgment It was set as the pass which was the resin composition which does not use the lead compound, and there was no shape loss and foaming during vulcanization, and passed both the tensile test and the radiation resistance test. The evaluation results are shown in Tables 1 and 2.

The average particle diameter and DBP oil absorption of carbon blacks 1 to 5 in Tables 1 and 2 are as follows. The average particle diameter is a value specified by visual observation using an electron microscope (Carbon Black Yearbook No. 61, 2011).
Carbon black 1: average particle size 45nm, DBP oil absorption 114ml / 100g
Carbon black 2: Average particle size 28nm, DBP oil absorption 75ml / 100g
Carbon black 3: average particle size 72nm, DBP oil absorption 72ml / 100g
Carbon black 4: average particle size 38nm, DBP oil absorption 133ml / 100g
Carbon black 5: average particle size 44nm, DBP oil absorption 106ml / 100g

  In Examples 1 to 5 using the resin composition within the range defined by the present invention, the tensile test and the radiation resistance test were both acceptable, and the comprehensive judgment was acceptable.

  On the other hand, in Comparative Example 1, there was no loss of shape and no problem in characteristics, but Lissajous (lead oxide) was used as the acid acceptor, which was rejected due to sanitary environment.

  In Comparative Example 2, since the amount of carbon black was sufficient but the aggregate was small, the shape was deformed when the cable 20 (small unit) was produced and when the flat cable 30 was produced.

  Since the aggregate of carbon black was small also in the comparative example 3 like the comparative example 2, since shape loss occurred, the comprehensive determination was made disqualified.

  In Comparative Example 4, since the amount of carbon black was small, the shape was lost. In addition, the cable was severely deformed and the sheath (resin composition 22) was partially thinned, so that the sheath was broken during a bending test for evaluating radiation resistance.

  In Comparative Example 5, contrary to Comparative Example 4, since the amount of carbon black was large, the elongation at break was small in the tensile test, and foaming was seen in the cross section of the cable.

  Since the comparative example 6 did not contain magnesium oxide and was vulcanized only with hydrotalcite, the vulcanization became sweet and the mold was deformed. Furthermore, foaming was observed in the cross section of the cable, the tensile strength was insufficient, and the shape was severely deformed, so that the sheath was broken in the bending test.

  Since Comparative Example 7 did not contain hydrotalcite, deterioration due to radiation was severe, and the bending test could pass but the ironing test failed.

  Comparative Example 8 uses a naphthenic process oil instead of an aromatic process oil. Although there was no problem in the shape loss, tensile properties, etc., as in Comparative Example 7, the radiation resistance was inferior and the bending test was rejected.

  In addition, this invention is not limited to the said embodiment and Example, A various deformation | transformation implementation is possible.

10: Cable, 20: Cable, 30: Flat cable 1: Conductor, 2: Insulator (PEEK), 3: Soft yarn 4: PET tape, 5: Metal braid, 6: Rubberized fabric tape 11: Polyarylate fiber Rope, 12: Unvulcanized rubber 13: Jute, 14: Radiation resistant resin composition 21: Pan cloth, 22: Radiation resistant resin composition

Claims (7)

Chlorosulfonated polyethylene, aromatic process oil, magnesium oxide, hydrotalcite, and carbon black having a dibutyl phthalate oil absorption of 100 ml / 100 g or more,
A radiation-resistant resin composition comprising 50 to 100 parts by mass of the carbon black with respect to 100 parts by mass of the chlorosulfonated polyethylene.   2. The radiation-resistant resin composition according to claim 1, comprising 20 to 80 parts by mass of the aromatic process oil and 10 to 30 parts by mass of the magnesium oxide with respect to 100 parts by mass of the chlorosulfonated polyethylene. .   Radiation resistance, characterized in that the periphery of a twisted electric wire formed by twisting a plurality of conductors coated with an insulator is coated with the radiation resistant resin composition according to claim 1 and vulcanized. Cable.   The radiation-resistant cable according to claim 3, wherein the insulator includes polyether ether ketone (PEEK).   A flat radiation-resistant cable, wherein the radiation-resistant cable according to claim 3 or 4 is covered with the radiation-resistant resin composition according to claim 1 or 2 and vulcanized.   The method for producing a radiation-resistant cable according to claim 3, further comprising a step of performing the vulcanization without leading.   The periphery of the radiation resistant cable produced by the method for producing a radiation resistant cable according to claim 6 is coated with the radiation resistant resin composition according to claim 1 or 2 and vulcanized without being lead-coated. A method for producing a flat radiation-resistant cable, comprising the step of:

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