JP2016134381A - Insulated wire and cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for producing an insulated wire and a cable excellent in fuel resistance and heat resistance with excellent productivity.SOLUTION: An insulated wire is provided with a conductor and an insulating layer provided on the outer periphery of the conductor. The insulating layer is formed of a non-halogen flame-retardant resin composition which contains an ethylene-vinyl acetate copolymer having a melting point by a DSC method at 70°C or higher and an acid-modified polyolefin resin, and contains a base polymer of which a content of the vinyl acetate derived from the ethylene-vinyl acetate copolymer is 25 mass% or more and 50 mass% or less, and a metal hydroxide. The insulated wire has such flame retardancy that a distance between the lower end of a support material and a carbonization starting point when a vertical flame test according to EN60332-1-2 is performed is 50 mm or more and such heat resistance that a tensile strength residual ratio after a heating test at 158°C for 168 hours is 60% or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an insulated wire and a cable.

  An insulated wire or cable is provided with a coating layer (insulating layer or sheath) so as to cover the outer periphery of the conductor. As these forming materials, non-halogen flame retardant resin compositions having no flame compound and having flame retardancy are used. As the non-halogen flame retardant resin composition, for example, a base polymer in which an ethylene-vinyl acetate copolymer (EVA) and a maleic acid-modified polyolefin are mixed with a metal hydroxide as a flame retardant is proposed. (For example, refer to Patent Document 1).

JP 2014-53247 A

  By the way, the coating layer of insulated wires and cables used as wiring for railway vehicles, automobiles, etc., is not easily deteriorated by fuel from the viewpoint of safety and durability, but also has excellent fuel resistance in addition to flame resistance. Is required.

  In order to improve fuel resistance, it is conceivable to use a highly polar polymer as the base polymer. However, if a highly polar polymer is used, the heat resistance of the coating layer may be impaired. Moreover, since the non-halogen flame retardant resin composition containing a highly polar polymer adheres to each other when pelletized, it is difficult to handle and it is difficult to form a coating layer with high productivity.

  Then, this invention aims at solving the said subject and providing the technique which manufactures the insulated wire and cable which are excellent in fuel resistance and heat resistance with sufficient productivity.

According to one aspect of the invention,
An insulated wire comprising a conductor and an insulating layer provided on the outer periphery of the conductor,
The insulating layer contains an ethylene-vinyl acetate copolymer having a melting point of 70 ° C. or higher and an acid-modified polyolefin resin by DSC method, and the vinyl acetate content derived from the ethylene-vinyl acetate copolymer is 25% by mass or more and 50% by mass. % Non-halogen flame retardant resin composition containing a base polymer and a metal hydroxide,
When performing a vertical combustion test in accordance with EN60332-1-2, flame retardancy in which the distance between the lower end of the upper support and the carbonization start point is 50 mm or more,
An insulated wire having a heat resistance with a residual tensile strength of 60% or more after a heating test at 158 ° C. for 168 hours is provided.

According to another aspect of the invention,
A cable comprising a conductor, an insulating layer provided on the outer periphery of the conductor, and a sheath provided on the outer periphery of the insulating layer,
The sheath contains an ethylene-vinyl acetate copolymer and an acid-modified polyolefin resin having a melting point of 70 ° C. or higher by DSC method, and the vinyl acetate content derived from the ethylene-vinyl acetate copolymer is 25 mass% or more and 50 mass%. It is formed from a non-halogen flame retardant resin composition containing the following base polymer and a metal hydroxide,
When performing a vertical combustion test in accordance with EN60332-1-2, flame retardancy in which the distance between the lower end of the upper support and the carbonization start point is 50 mm or more,
There is provided a cable having a heat resistance with a residual tensile strength of 60% or more after a heating test at 158 ° C. for 168 hours.

  According to the present invention, an insulated wire and a cable excellent in flame retardancy, fuel resistance and heat resistance can be obtained.

It is sectional drawing of the insulated wire which concerns on one Embodiment of this invention. It is sectional drawing of the cable which concerns on one Embodiment of this invention.

<One Embodiment of the Present Invention>
Hereinafter, an embodiment of the present invention will be described.

(1) Configuration of insulated wire An insulated wire according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of an insulated wire according to an embodiment of the present invention.

  As illustrated in FIG. 1, the insulated wire 10 includes a conductor 11 and an insulating layer 12 provided on the outer periphery of the conductor 11.

  As the conductor 11, a commonly used metal wire, for example, a copper wire, a copper alloy wire, an aluminum wire, a gold wire, a silver wire, or the like can be used. Moreover, you may use what gave metal plating, such as tin and nickel, to the outer periphery of a metal wire. Further, a collective stranded conductor obtained by twisting metal wires can be used.

  The insulating layer 12 is provided so as to cover the conductor 11. The insulating layer 12 is formed from a crosslinked product obtained by crosslinking a non-halogen flame retardant resin composition described later. The method for producing the insulating layer 12 is produced, for example, by extruding a non-halogen flame retardant resin composition on the outer periphery of the conductor 11 with a predetermined thickness and crosslinking it.

(2) Non-halogen flame retardant resin composition forming an insulating layer The non-halogen flame retardant resin composition (hereinafter also simply referred to as non-halogen material) contains a base polymer, a metal hydroxide, and an antioxidant. Configured. Hereinafter, each component will be described.

[Base polymer]
The base polymer includes an ethylene-vinyl acetate copolymer having a melting point of 70 ° C. or higher by an DSC method and an acid-modified polyolefin resin.

(Ethylene-vinyl acetate copolymer)
An ethylene-vinyl acetate copolymer (hereinafter, also simply referred to as EVA) includes vinyl acetate (VA) having a polar group and has a predetermined polarity. Polar EVA has excellent flame retardancy and fuel resistance. In the present embodiment, among such EVAs, EVA having a melting point (Tm) measured by a differential scanning calorimetry (DSC method) of 70 ° C. or higher is used. In general, EVA deteriorates when acetic acid is desorbed by heating and the main chain is decomposed. However, EVA having a Tm of 70 ° C. or higher has a relatively small amount of VA and has little acetic acid desorption due to heating. It is less likely to deteriorate and has excellent heat resistance. Furthermore, since the tackiness of the non-halogen material can be reduced, it is possible to suppress sticking of pellets to each other (so-called blocking) when pelletized. On the other hand, EVA having a Tm of less than 70 ° C. is excellent in flame retardancy but is not only inferior in heat resistance, but also increases the tackiness of the non-halogen material and causes blocking. The upper limit value of EVA Tm is not particularly limited, but as described later, from the viewpoint of easily adjusting the amount of VA in the base polymer to a range of 25% by mass or more and 50% by mass or less, preferably 100 ° C. or less. Preferably it is 95 degrees C or less, More preferably, it is 90 degrees C or less. Note that EVA having a melting point of 70 ° C. or higher and 100 ° C. or lower has a VA amount of 6% by mass or more and 28% by mass or less, for example.

  The base polymer may contain at least one type of EVA having a Tm of 70 ° C. or higher, and may contain two or more types of EVA having different Tm. Preferably, three types of EVA having a Tm of 70 ° C. or higher are included, and more preferably, two types of EVA having a Tm of 70 ° C. or higher are included. In the present embodiment, EVA having Tm of less than 70 ° C. may be included in addition to EVA having Tm of 70 ° C. or higher. EVA having a Tm of less than 70 ° C. is a polymer having a larger amount of VA and lower crystallinity than EVA having a Tm of 70 ° C. or more. EVA having a Tm of less than 70 ° C. has, for example, a VA amount of 28% by mass or more. By using such EVA together, the VA amount in the base polymer is adjusted to a range of 25% by mass to 50% by mass. It becomes easy.

  The EVA preferably has a melt mass flow rate (MFR) of 6 g / 10 min or more. More preferably, the MFR of EVA having a Tm of 70 ° C. or higher is 6 g / 10 min or higher. By using such EVA, the fluidity when the non-halogen material is melted can be improved, and the productivity when the non-halogen material is extruded to form the insulating layer 12 can be improved. In addition, when using 2 or more types of EVA, it is good that at least 1 type of MFR of these is 6 g / 10min or more.

(Acid-modified polyolefin resin)
The acid-modified polyolefin resin is, for example, a polyolefin modified with an unsaturated carboxylic acid or a derivative thereof. The acid-modified polyolefin resin can improve the adhesion between the base polymer and the metal hydroxide, suppress the penetration / diffusion of the fuel oil or the like into the interface, and suppress the interface breakdown at a low temperature. That is, the acid-modified polyolefin resin improves the fuel resistance and cold resistance of the non-halogen material.

  Examples of the polyolefin material of the acid-modified polyolefin resin include ultra-low density polyethylene, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butene-1 copolymer, and ethylene-hexene-1 copolymer. And ethylene-octene-1 copolymer. Examples of the acid that modifies the polyolefin include maleic acid, maleic anhydride, and fumaric acid. These acid-modified polyolefin resins may be used alone or in combination of two or more.

  The acid-modified polyolefin resin preferably has a glass transition point (Tg) of −55 ° C. or lower. According to the acid-modified polyolefin resin having a Tg of −55 ° C. or lower, the Tg of the base polymer can be lowered, and cracking when the insulating layer 12 is exposed to a low temperature environment can be suppressed. That is, the cold resistance of the insulating layer 12 can be improved.

(VA amount in base polymer)
The base polymer contains EVA and acid-modified polyolefin resin, and contains vinyl acetate (VA) derived from EVA in a predetermined ratio. The VA amount in the base polymer is calculated by the following equation (1) when there are 1, 2, 3.

（式（１）中、Ｘ_ｋは、ある種類ｋのＥＶＡのＶＡ量（質量％）を、Ｙ_ｋは、ある種類ｋのＥＶＡがベースポリマ全体に占める割合を、そしてｋは自然数を、それぞれ示す。）

(In Formula (1), X _k is the VA amount (mass%) of EVA of a certain type k, Y _k is the ratio of the EVA of a certain type k to the entire base polymer, and k is a natural number, respectively. Show.)

  The amount of VA in the base polymer is 25% by mass or more and 50% by mass or less. Preferably, they are 25 mass% or more and 46 mass% or less, More preferably, they are 25 mass% or more and 35 mass% or less. When the amount of VA in the base polymer is less than 25% by mass, the polarity of the base polymer becomes excessively small, so that the flame retardancy and fuel resistance of the insulating layer 12 become insufficient. On the other hand, if the amount of VA exceeds 50% by mass, the amount of acetic acid desorbed from EVA when the base polymer is heated to a high temperature increases, so that the EVA contained in the base polymer tends to deteriorate and the insulating layer 12 The heat resistance will be low. Further, the non-halogen material is easily blocked, and the insulating layer 12 cannot be formed with high productivity.

  The amount of VA in the base polymer can be appropriately changed depending on the ratio (mass ratio) between EVA having VA and the acid-modified polyolefin resin. The ratio should just be a ratio from which the VA amount in a base polymer will be 25 to 50 mass%. Preferably, the ratio of EVA to acid-modified polyolefin resin is 70:30 to 99: 1. That is, with respect to the base polymer, the EVA content is 70% by mass or more and 99% by mass or less, and the acid-modified polyolefin resin content is 1% by mass or more and 30% by mass or less.

  The base polymer preferably contains only EVA and an acid-modified polyolefin resin, but may contain other polymers other than EVA and the acid-modified polyolefin resin as long as the characteristics of the non-halogen material are not impaired. In this case, the total content of EVA and acid-modified polyolefin resin is preferably 90% by mass or more, more preferably 95% by mass or more, and further preferably 100% by mass with respect to the base polymer.

  The non-halogen material contains a metal hydroxide as a flame retardant. When the non-halogen material is heated and burned, the metal hydroxide decomposes and dehydrates, lowers the temperature of the non-halogen material by the released moisture, and suppresses the combustion. Examples of the metal hydroxide that can be used include magnesium hydroxide, aluminum hydroxide, calcium hydroxide, and metal hydroxides in which nickel is dissolved. These non-halogen flame retardants may be used alone or in combination of two or more. While the endothermic amount of calcium hydroxide is 1000 J / g, the endothermic amount of magnesium hydroxide or aluminum hydroxide is as high as 1500 J / g or more and 1600 J / g or less, so that at least one of magnesium hydroxide and aluminum hydroxide is present. It is preferable to use seeds.

  From the point that it is easy to control the mechanical properties (balance between tensile strength and elongation) of the insulating layer 12, the metal hydroxide is a silane coupling agent, a titanate coupling agent, fatty acids such as stearic acid, stearates, etc. It is preferable that the surface is treated with a fatty acid metal such as a fatty acid salt or calcium stearate.

  The content of the metal hydroxide is preferably 100 parts by mass or more and 250 parts by mass or less with respect to 100 parts by mass of the base polymer. There exists a possibility that the flame retardance of the insulating layer 12 may become it low that content is less than 100 mass parts. When content exceeds 250 mass parts, the mechanical characteristic of the insulating layer 12 will fall, and elongation rate will become low.

  The non-halogen material may contain other additives as necessary. For example, when the insulating layer 12 is crosslinked, a crosslinking agent or a crosslinking aid may be included. Examples of the crosslinking method include an irradiation crosslinking method in which the insulating layer 12 is crosslinked by irradiating with an electron beam or radiation, and a chemical crosslinking method in which the insulating layer 12 is heated to be crosslinked. In the case of the irradiation crosslinking method, a crosslinking assistant may be contained in the non-halogen material. As the crosslinking aid, for example, trimethylolpropane triacrylate (TMPT), triallyl isocyanurate (TAIC: registered trademark), or the like can be used. In the case of the chemical crosslinking method, a non-halogen material may contain a crosslinking agent. As the crosslinking agent, for example, organic peroxides such as 1,3-bis (2-t-butylperoxyisopropyl) benzene and dicumyl peroxide (DCP) can be used.

  In addition to the crosslinking agent, the non-halogen material contains flame retardant aids, antioxidants, lubricants, softeners, plasticizers, inorganic fillers, compatibilizers, stabilizers, carbon black, colorants, and the like. Also good. These can be contained as long as the characteristics of the non-halogen material are not impaired.

  The non-halogen material can be obtained by mixing the above-mentioned EVA, acid-modified polyolefin, metal hydroxide, and other additives as necessary, and kneading while heating. The kneading conditions and the order of adding each component are not particularly limited. The kneading can be performed using a mixing roll, a Banbury mixer, a single-screw or twin-screw extruder, and the like.

<Effects of Embodiment of the Present Invention>
According to the present embodiment, the following one or more effects are achieved.

(A) In the insulated wire 10 of this embodiment, the amount of vinyl acetate (VA amount) derived from EVA is 25 mass% or more and 50 mass% or less with EVA and acid-modified polyolefin resin having a melting point (Tm) of 70 ° C. or higher. The insulating layer 12 is formed using a non-halogen material containing a base polymer blended as described above. Since such an insulating layer 12 has a predetermined high polarity, it is excellent in flame retardancy and fuel resistance. Further, since the insulating layer 12 is configured to include EVA having a Tm of 70 ° C. or more and a relatively small amount of VA so that the amount of VA in the base polymer is 50% by mass or less, the heat resistance is improved. Is also excellent.

(B) In the present embodiment, the amount of VA in the base polymer is set to 50% by mass or less so that the polarity of the base polymer is not excessively increased. In addition, EVA having a Tm of 70 ° C. or higher and high crystallinity is used. Thereby, the adhesiveness of a non-halogen material can be suppressed, and when a non-halogen material is pelletized, it can suppress that a pellet adheres and blocks. By using such a non-halogen material, the insulating layer 12 can be formed with high productivity.

(C) In this embodiment, the content of the metal hydroxide is set to 100 parts by mass or more and 250 parts by mass or less with respect to 100 parts by mass of the base polymer. Thereby, flame retardance can be improved without impairing the mechanical strength (tensile strength and elongation) of the insulating layer 12.

(D) In this embodiment, an acid-modified polyolefin resin having a glass transition point of −55 ° C. or lower is used. Thereby, the glass transition point of the base polymer can be lowered, and the cold resistance of the insulating layer 12 can be improved.

(E) In this embodiment, the ratio of predetermined EVA to acid-modified polyolefin resin is set to 70:30 to 99: 1. Thereby, fuel resistance and cold resistance can be improved in a well-balanced manner without deteriorating the mechanical properties of the insulating layer 12.

(F) In the present embodiment, EVA having a Tm of 70 ° C. or higher has a melt flow rate of 6 g / 10 min or higher. Thereby, since fluidity | liquidity when a non-halogen material is fuse | melted can be improved, the insulating layer 12 can be formed with high productivity.

(G) In this embodiment, since the insulating layer 12 does not contain halogen, no halogen gas is generated during combustion.

<Other Embodiments of the Present Invention>
As mentioned above, although one Embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the summary, it can change suitably.

In the above-described embodiment, the case where the insulating layer 12 is configured with a single layer structure has been described. However, the insulating layer 12 may be configured with a multilayer structure including a plurality of resin layers. When the insulating layer 12 has a multilayer structure, the above-mentioned non-halogen material may be used for each layer of the multilayer structure, the above-mentioned non-halogen material is used for the outermost layer, and a polyolefin resin or rubber material is used for layers other than the outermost layer. A multilayer structure may be used.
Examples of the polyolefin resin include low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-glycidyl methacrylate copolymer, and maleic anhydride polyolefin. be able to. These polyolefin resins may be used individually by 1 type, and may use 2 or more types together.
Examples of rubber materials include ethylene-propylene copolymer rubber (EPR), ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene rubber (NBR), hydrogenated NBR (HNBR), and acrylic rubber. , Ethylene-acrylic acid ester copolymer rubber, ethylene octene copolymer rubber (EOR), ethylene-vinyl acetate copolymer rubber, ethylene-butene-1 copolymer rubber (EBR), butadiene-styrene copolymer rubber (SBR), isobutylene-isoprene copolymer rubber (IIR), block copolymer rubber having a polystyrene block, urethane rubber, phosphazene rubber, and the like can be used. These rubber materials may be used individually by 1 type, or may use 2 or more types together.

  Moreover, you may provide a separator, a braid, etc. in the insulated wire 10 as needed.

  In the above-described embodiment, the case of the insulated wire 10 using a non-halogen material for the insulating layer 12 has been described. However, for example, as shown in FIG. 2, a non-halogen material can be used for the sheath 22 of the cable 20. is there. FIG. 2 is a cross-sectional view of the cable 20 according to an embodiment of the present invention.

  A cable 20 according to an embodiment of the present invention includes a two-core stranded wire 21 formed by twisting two insulated wires 10 illustrated in FIG. 1 and a sheath 22 provided on the outer periphery of the two-core stranded wire 21. It is configured. The sheath 22 is formed from a crosslinked product obtained by crosslinking the above-described non-halogen material. The cable 20 of this embodiment is excellent in flame retardancy, fuel resistance, and heat resistance because the sheath 22 is formed of the above-described non-halogen material.

  The sheath 22 may have a single layer structure as shown in FIG. 2 or a laminated structure in which a plurality of resin layers are laminated. In the case of a laminated structure, the above-mentioned non-halogen material may be used for each layer of the multilayer structure, the above-described non-halogen material is used for the outermost layer, and the polyolefin resin or rubber material is used for the layers other than the outermost layer. It is good.

  In addition, although FIG. 2 demonstrated the case where the two insulated wires 10 were twisted together, you may twist one or three or more. Moreover, although the case where a cable was comprised with the insulated wire 10 of FIG. 1 was demonstrated, you may comprise the cable 20 using the insulated wire which provided the insulating layer which consists of a general purpose non-halogen material.

  Next, the present invention will be described more specifically with reference to examples. The present invention is not limited to the following examples.

(1) Raw materials The raw materials used for the non-halogen materials are as follows.

The following was used as EVA.
EVA (Tm: 89 ° C., MFR: 15 g / 10 min, VA amount: 14% by mass): “Evaflex EV550” manufactured by Mitsui DuPont Polychemical Co., Ltd.
EVA (Tm: 72 ° C., MFR: 6 g / 10 min, VA amount: 28% by mass): “Evaflex EV260” manufactured by Mitsui DuPont Polychemical Co., Ltd.
EVA (Tm: less than 70 ° C., MFR: 100 g / 10 min, VA amount: 46 mass%): “Evaflex 45X” manufactured by Mitsui DuPont Polychemical Co., Ltd.
EVA (Tm: less than 70 ° C., MFR: 2.5 g / 10 min, VA amount: 46% by mass): “Evaflex EV45LX” manufactured by Mitsui DuPont Polychemical Co., Ltd.
EVA (Tm: 62 ° C., MFR: 1 g / 10 min, VA amount: 33% by mass): “Evaflex EV170” manufactured by Mitsui DuPont Polychemical Co., Ltd.
EVA (Tm: less than 70 ° C., MFR: 5.1 g / 10 min, VA amount: 80% by mass): “Levaprene 800” manufactured by LANXESS Corporation

The following were used as the acid-modified polyolefin.
Acid-modified polyolefin (Tm: 70 ° C., Tg: −50 ° C. or less): “Toughma-MA8510” manufactured by Mitsui Chemicals, Inc.

The following were used as metal hydroxides.
Magnesium hydroxide (Silane treatment): “MAGNIFIN H10A” manufactured by Albemarle Co., Ltd.
Magnesium hydroxide (fatty acid treatment): “MAGNIFIN H10C” manufactured by Albemarle Co., Ltd.
Aluminum hydroxide (Silane treatment): “BF013STV” manufactured by Nippon Light Metal Co., Ltd.
Aluminum hydroxide (fatty acid treatment): “Hijilite H42S” manufactured by Showa Denko KK

The following were used as other additives.
・ Crosslinking aid (trimethylolpropane trimethacrylate): “TMPT” manufactured by Shin-Nakamura Chemical Co., Ltd.

(2) Preparation of non-halogen material As shown in Table 1 and Table 2 below, various components were blended, kneaded by a pressure kneader at a start temperature of 40 ° C and an end temperature of 200 ° C, then pelletized, and Examples 1 to 6 and Non-halogen materials of Comparative Examples 1 to 3 were prepared. In Tables 1 and 2, the numerical values are shown in parts by mass.

(3) Production of cable First, a twisted conductor prepared by twisting 19 conductors having a diameter of 0.18 mm was prepared. Subsequently, using a 65 mm extruder, the outer periphery of the twisted conductor was extrusion-coated with ethylene propylene rubber at 150 ° C., and then irradiated with a 10 Mrad electron beam to obtain an insulated wire. Two insulated wires obtained were prepared and twisted together to produce a two-core stranded wire. Subsequently, using a 90 mm extruder, the non-halogen material prepared in (2) above was extrusion coated at 120 ° C. on the outer periphery of the two-core stranded wire so that the outer diameter was 4.4 mm, and then 4 Mrad of A cable was obtained by irradiating with an electron beam and crosslinking.

(4) Evaluation method The obtained cable was evaluated by the method shown below.

(Normal temperature storage)
In order to evaluate the storage stability at normal temperature, non-halogen materials were stored at normal temperature to evaluate whether blocking occurred. Specifically, 20 kg of the pelletized non-halogen material was packed in a 420 mm × 820 mm paper bag, and two paper bags were stacked in a constant temperature bath at 40 ° C. and stored for 240 hours. Thereafter, the pellet was opened in a bat and it was confirmed whether the pellet was blocking. If blocking did not occur, it was determined as “Pass”, and if blocking occurred, it was determined as “Fail”.

(Flame retardancy test)
About the produced cable, the vertical combustion test was done based on EN603332-1-2. Judgment made the pass "(circle)" if the distance of the lower end part of an upper support material and the carbonization start point was 50 mm or more after flame extinction, and disqualified "x" if less than 50 mm.

(Fuel resistance test)
The sheath was peeled off from the produced cable, and the obtained sheath was subjected to a fuel resistance test in accordance with EN60881-1-3 to evaluate the fuel resistance. Specifically, the sheath was immersed in a fuel resistance test oil IRM903, heated in a thermostatic bath at 70 ° C. for 168 hours, and allowed to stand at room temperature for 16 hours, and then a tensile test was performed. And about the sheath, the tensile strength residual rate of the tensile strength after the oil immersion with respect to the initial tensile strength (before the oil immersion) and the elongation residual rate of the elongation rate after the oil immersion with respect to the initial elongation rate were measured. . When the residual tensile strength was 70% or more, “◯” was indicated, and when it was less than 70%, “X” was indicated. Moreover, when the residual elongation rate was 60% or more, “◯” was indicated, and when it was less than 60%, “X” was indicated.

(Heat resistance test)
The sheath was peeled off from the produced cable, and the obtained sheath was subjected to a heat resistance test in accordance with GB / T2951, 12-2008, and the heat resistance was evaluated. Specifically, it was heated in a constant temperature bath at 158 ° C. for 168 hours, left at room temperature for 24 hours, and then subjected to a tensile test. And about the sheath, the elongation residual rate of the elongation rate after a heating with respect to the elongation rate of an initial stage (before a heating) was measured. When the residual elongation rate was 60% or more, the test was “good”, and when it was less than 60%, the test was “failed”.

(Comprehensive evaluation)
In the comprehensive evaluation, a case where all evaluations were “good” was evaluated as “good”, and if any evaluation was “×”, it was determined as “failed”.

(5) Evaluation results As shown in Table 1, in Examples 1 to 6, all evaluations were ◯, and the overall evaluation was ◯.

In Comparative Example 1, it was confirmed that sufficient flame retardancy could not be obtained because the amount of VA in the base polymer was less than 25% by mass.
In Comparative Example 2, it was confirmed that heat resistance was low because EVA having a Tm of 70 ° C. or higher was not used and the VA amount of the base polymer exceeded 50 mass%. Further, it was confirmed that the non-halogen material was blocked and the room temperature storage property was poor. As a result, a step of pulverizing the blocked pellets is required, and the sheath could not be formed with high productivity.
In Comparative Example 3, it was confirmed that the Tm of EVA contained in the base polymer was all less than 70 ° C., so that the room temperature storage property was poor and the fuel resistance was low.

<Preferred embodiment of the present invention>
Hereinafter, preferred embodiments of the present invention will be additionally described.

[Appendix 1]
According to one aspect of the invention,
An insulated wire comprising a conductor and an insulating layer provided on the outer periphery of the conductor,
The insulating layer is
A base comprising an ethylene-vinyl acetate copolymer and an acid-modified polyolefin resin having a melting point of 70 ° C. or higher by DSC method, wherein the vinyl acetate content derived from the ethylene-vinyl acetate copolymer is 25 mass% or more and 50 mass% or less Formed from a non-halogen flame retardant resin composition containing a polymer and a metal hydroxide,
When performing a vertical combustion test in accordance with EN60332-1-2, flame retardancy in which the distance between the lower end of the upper support and the carbonization start point is 50 mm or more,
An insulated wire having a heat resistance with a residual tensile strength of 60% or more after a heating test at 158 ° C. for 168 hours is provided.

[Appendix 2]
The insulated wire according to appendix 1, preferably,
At least one of the ethylene-vinyl acetate copolymers contained in the base polymer has a melt flow rate of 6 g / 10 min or more.

[Appendix 3]
The insulated wire according to appendix 1 or 2, preferably,
The metal hydroxide is magnesium hydroxide or aluminum hydroxide.

[Appendix 4]
The insulated wire according to any one of appendices 1 to 3, preferably,
The metal hydroxide is treated with silane or fatty acid.

[Appendix 5]
According to another aspect of the invention,
A cable comprising a conductor, an insulating layer provided on the outer periphery of the conductor, and a sheath provided on the outer periphery of the insulating layer,
The sheath is
A base comprising an ethylene-vinyl acetate copolymer and an acid-modified polyolefin resin having a melting point of 70 ° C. or higher by DSC method, wherein the vinyl acetate content derived from the ethylene-vinyl acetate copolymer is 25 mass% or more and 50 mass% or less Formed from a non-halogen flame retardant resin composition containing a polymer and a metal hydroxide,
When performing a vertical combustion test in accordance with EN60332-1-2, flame retardancy in which the distance between the lower end of the upper support and the carbonization start point is 50 mm or more,
There is provided a cable having a heat resistance with a residual tensile strength of 60% or more after a heating test at 158 ° C. for 168 hours.

[Appendix 6]
The cable of appendix 5, preferably
At least one of the ethylene-vinyl acetate copolymers contained in the base polymer has a melt flow rate of 6 g / 10 min or more.

[Appendix 7]
Additional cable 5 or 6, preferably,
The metal hydroxide is magnesium hydroxide or aluminum hydroxide.

[Appendix 8]
The cable according to any one of appendices 5 to 7, preferably
The metal hydroxide is treated with silane or fatty acid.

DESCRIPTION OF SYMBOLS 10 Insulated electric wire 11 Conductor 12 Insulating layer 20 Cable 21 2 core strand wire 22 Sheath

Claims (8)

An insulated wire comprising a conductor and an insulating layer provided on the outer periphery of the conductor,
The insulating layer is
A base comprising an ethylene-vinyl acetate copolymer and an acid-modified polyolefin resin having a melting point of 70 ° C. or higher by DSC method, wherein the vinyl acetate content derived from the ethylene-vinyl acetate copolymer is 25 mass% or more and 50 mass% or less Formed from a non-halogen flame retardant resin composition containing a polymer and a metal hydroxide,
When performing a vertical combustion test in accordance with EN60332-1-2, flame retardancy in which the distance between the lower end of the upper support and the carbonization start point is 50 mm or more,
An insulated wire having a heat resistance with a residual tensile strength of 60% or more after a heating test at 158 ° C. for 168 hours.   The insulated wire according to claim 1, wherein at least one of the ethylene-vinyl acetate copolymers contained in the base polymer has a melt flow rate of 6 g / 10 min or more.   The insulated wire according to claim 1 or 2, wherein the metal hydroxide is magnesium hydroxide or aluminum hydroxide.   The insulated wire according to any one of claims 1 to 3, wherein the metal hydroxide is treated with a silane or a fatty acid. A cable comprising a conductor, an insulating layer provided on the outer periphery of the conductor, and a sheath provided on the outer periphery of the insulating layer,
The sheath is
A base comprising an ethylene-vinyl acetate copolymer and an acid-modified polyolefin resin having a melting point of 70 ° C. or higher by DSC method, wherein the vinyl acetate content derived from the ethylene-vinyl acetate copolymer is 25 mass% or more and 50 mass% or less Formed from a non-halogen flame retardant resin composition containing a polymer and a metal hydroxide,
When performing a vertical combustion test in accordance with EN60332-1-2, flame retardancy in which the distance between the lower end of the upper support and the carbonization start point is 50 mm or more,
And a heat resistance having a tensile strength residual ratio of 60% or more after a heating test at 158 ° C. for 168 hours.   The cable according to claim 5, wherein at least one of the ethylene-vinyl acetate copolymers contained in the base polymer has a melt flow rate of 6 g / 10 min or more.   The cable according to claim 5 or 6, wherein the metal hydroxide is magnesium hydroxide or aluminum hydroxide.   The cable according to claim 5, wherein the metal hydroxide is treated with silane or with a fatty acid.

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