JP2019192459A - cable - Google Patents

Abstract

To provide a cable having a polyamide-polyethylene bilayer structure, sufficiently high in adhesiveness between a polyamide layer and a polyethylene layer and hardly generating detachment between both of them.SOLUTION: A cable 1 has a linear conductor part 10 and a coating part 20A coating an outer peripheral side thereof. The coating part 20A contains a polyamide layer 34 and a polyethylene layer 32 conjugated to the polyamide layer 34 in contact. At least one of the polyamide layer 34 and the polyethylene layer 32 is a modifier-containing layer containing a modifier. Shore D hardness of the polyamide layer 34 is 65 or more. The modifier has melting point of 75°C to 115°C. The modifier contains an acid component of 0.5 mass% to 20 mass% and an ethylene component of 50 mass% or more in 100 mass% of the modifier. Content of the modifier in the modifier-containing layer is 2 mass% to 40 mass% based on 100 mass% of total mass of the modifier-containing layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cable.

  With the development of a cable network for power supply and information transmission, maintenance of installed cables has become an important issue. For example, when a cable is buried in the ground, the sheath (skin layer) of the cable may be damaged by termites. Therefore, in order to maintain the cable, there is a strong demand to prevent the damage caused by termites.

  2. Description of the Related Art A cable having an ant-proof layer made of polyamide (nylon) is known as a cable having an ant-proof effect for preventing corrosion caused by termites. Since polyamide is a hard plastic material, it is not easily damaged by termites. For example, Patent Document 1 discloses a cable including a polyolefin resin layer and an ant-proof layer made of nylon. Patent Document 2 discloses a manufacturing apparatus and a manufacturing method for a multilayer sheath cable including an inner layer made of polyethylene or polyvinyl chloride and an outer layer made of nylon.

JP-A-9-102220 JP-A-6-314523

  As a covering material constituting the covering portion of the cable, polyethylene having high flexibility and high electrical insulation is often used. As described above, the polyamide (nylon) layer is useful as an anti-corrosion layer for cables, but has a problem of low adhesion to polyethylene. Therefore, when a covering material including a laminate in which a polyethylene layer and a polyamide layer are laminated is used as a cable covering material, peeling may occur between the polyethylene layer and the polyamide layer. In particular, when the adhesive force between the polyethylene layer and the polyamide layer is low, peeling occurs easily when the cable is bent. When such peeling occurs, it becomes difficult to form the cable cover, when wrinkles occur between the polyethylene layer and the polyamide layer, making it difficult to use, or the polyamide layer has an adequate ant-proof effect. There may be cases where it is not done. Therefore, it is required to increase the adhesion between the polyamide layer and the polyethylene layer.

  In order to bond the polyamide layer and the polyethylene layer, for example, in Patent Document 1 described above, it is proposed to provide an adhesive layer made of an adhesive polymer. However, the process for forming the adhesive layer is complicated and the productivity is lowered, and the problem of durability of the adhesive layer itself may newly arise. Therefore, the polyamide layer and the polyethylene layer are not connected via the adhesive layer. It is desirable to be able to laminate directly. Of course, even if the polyamide layer and the polyethylene layer are directly laminated, it is desirable that the two layers be bonded with a sufficiently high adhesive force.

  Therefore, there is a cable having a polyamide-polyethylene multilayer structure in which the adhesion between the polyamide layer and the polyethylene layer is sufficiently high without peeling through other layers such as an adhesive layer, and peeling between the two layers hardly occurs. It has been demanded.

  An object of the present invention is a cable having a polyamide-polyethylene multilayer structure, sufficiently high adhesion between the polyamide layer and the polyethylene layer, and sufficient hardness of the polyamide layer, and heat resistance and insulation characteristics of the polyethylene layer. Is to provide.

  The cable of this application is provided with a linear conductor part and the coating | coated part which covers the outer peripheral side of a conductor part. The covering portion includes a polyamide layer and a polyethylene layer bonded in contact with the polyamide layer. At least one of the polyamide layer and the polyethylene layer is a modifier-containing layer containing a modifier. The Shore D hardness of the polyamide layer is 65 or more. The modifier has a melting point of 75 ° C. or higher and 115 ° C. or lower. The modifier includes 0.5% by mass or more and 20% by mass or less of an acid component and 50% by mass or more of an ethylene component out of 100% by mass of the modifier. The content of the modifier in the modifier-containing layer is 2% by mass to 40% by mass with respect to 100% by mass of the total mass of the modifier-containing layer.

  According to the cable of the present application, it has a polyamide-polyethylene multilayer structure, the adhesiveness between the polyamide layer and the polyethylene layer is sufficiently high, and the hardness of the polyamide layer and the heat resistance of the polyethylene layer are improved even if the adhesiveness is improved. It is possible to provide a cable with sufficient performance and insulation characteristics.

2 is a schematic cross-sectional view showing the cable according to Embodiment 1. FIG. It is an expanded sectional view of a polyethylene layer and a polyamide layer 6 is a schematic cross-sectional view showing a cable according to Embodiment 2. FIG.

[Description of Embodiment of Present Invention]
First, embodiments of the present invention will be listed and described. The cable of this application is provided with a linear conductor part and the coating | coated part which covers the outer peripheral side of a conductor part. The covering portion includes a polyamide layer and a polyethylene layer bonded in contact with the polyamide layer. At least one of the polyamide layer and the polyethylene layer is a modifier-containing layer containing a modifier. The Shore D hardness of the polyamide layer is 65 or more. The modifier has a melting point of 75 ° C. or higher and 115 ° C. or lower. The modifier contains 0.5% by mass or more and 20% by mass or less of an acid component and 50% by mass or more of an ethylene component out of 100% by mass of the modifier. The content of the modifier in the modifier-containing layer is 2% by mass to 40% by mass with respect to 100% by mass of the total mass of the modifier-containing layer.

  The polyamide layer has high hardness (specifically, Shore D hardness) and has an ant-proof effect. On the other hand, the polyethylene layer is excellent in flexibility, heat resistance, water resistance, electrical insulation and the like. Polyamide-polyethylene in which the two layers are directly bonded without greatly deteriorating the properties inherent in the polyamide layer and the polyethylene layer, by containing at least one of the polyamide layer and the polyethylene layer with the modifier. A multilayer structure can be formed.

  The modifier has a melting point of 75 ° C. or higher and 115 ° C. or lower. When the modifying agent has a melting point of 75 ° C. or higher, the two layers can be directly bonded without significantly impairing the heat resistance of the cable. On the other hand, when the modifier has a melting point of 115 ° C. or lower, compatibility with the polyamide layer and the polyethylene layer is enhanced, and the effect of imparting adhesiveness by the modifier is sufficiently exhibited.

  Moreover, the said modifier contains 0.5 mass% or more and 20 mass% or less of an acid component, and 50 mass% or more of ethylene components among 100 mass% of modifiers. When the modifier contains 0.5% by mass or more of the acid component, the polyamide layer and the polyethylene layer can be directly bonded with sufficient adhesive strength. Moreover, it can suppress that durability (water resistance, heat resistance, etc.) of a cable is impaired significantly because the quantity of an acid component is 20 mass% or less. In addition, when the modifier contains 50% by mass or more of an ethylene component, compatibility with the polyethylene layer can be improved and the adhesive strength can be further improved.

  The content of the modifier in the modifier-containing layer is 2% by mass or more and 40% by mass or less with respect to 100% by mass of the total mass of the modifier-containing layer. When the amount of the modifier is 2% by mass or more, a sufficient adhesive force can be secured between the polyamide layer and the polyethylene layer. In addition, when the amount of the modifier is 40% by mass or less, the two layers can be directly joined without greatly impairing the characteristics inherent to the polyamide layer and the polyethylene layer.

  Thus, according to the present application, there is provided a cable having the above-described various characteristics and particularly suitable for use as an ant-proof cable.

  In the cable, the modifier may be dispersed inside the modifier-containing layer as modifier particles. In this case, the average particle diameter of the modifier particles may be 1000 μm or less. When the modifier particles having the average particle diameter are dispersed in the layer, the effect of improving the adhesion between the polyamide layer and the polyethylene layer by the modifier is effectively exhibited evenly over the entire layer.

  In the above cable, the modifier may be a copolymer of ethylene and at least one comonomer selected from (meth) acrylic acid and (anhydrous) maleic acid. The modifier containing these copolymers has good compatibility with both polyamide and polyethylene, and can more reliably exhibit the effect of improving adhesiveness. In the present application, “(meth) acrylic acid” means at least one of acrylic acid, methacrylic acid, or a combination of acrylic acid and methacrylic acid. “(Maleic anhydride)” means at least one of maleic acid, maleic anhydride, or a combination of maleic acid and maleic anhydride.

  In the cable, the amount of heat deformation of the polyethylene layer under the conditions of a temperature of 75 ° C. and a load of 1 kg may be less than 20%. Such a cable can be suitably used as a cable having excellent heat resistance.

In the above cable, the insulation resistance of the polyethylene layer under the conditions of a temperature of 40 ° C. and an electric field strength of 60 kV / mm may be greater than 1.0 × 10 ¹² Ω · cm. Such a cable can be suitably used as a cable having excellent insulation characteristics.

[Details of the embodiment of the present invention]
Next, an embodiment of the cable of the present application will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

(Embodiment 1)
[Cable structure]

  FIG. 1 is a schematic cross-sectional view showing a cable according to the first embodiment. With reference to FIG. 1, the cable 1 is provided with the linear conductor part 10 in the center. A covering portion 20 </ b> A is arranged on the outer side in the radial direction of the conductor portion 10 so as to cover the outer peripheral side of the conductor portion 10. The covering portion 20A has an inner semiconductive layer 22, an insulating layer 24, an outer semiconductive layer 26, a shielding layer 28, a pressing tape 30, a polyethylene layer 32, and a polyamide layer 34 in order from the center of the cable 1 to the radially outer side. Is provided.

  The conductor part 10 has conductivity and transmits a current and an electric signal. In the cable 1 shown in FIG. 1, the linear conductor part 10 has a circular shape in a cross section perpendicular to the longitudinal direction. However, the cross-sectional shape of the conductor portion 10 is not limited to a circular shape, and may be another shape such as a sector shape. As a material constituting the conductor portion 10, a metal having a low electrical resistivity such as copper or aluminum is used.

  The internal semiconductive layer 22 is provided for the purpose of improving the adhesion between the conductor portion 10 and the insulating layer 24, preventing the generation of voids (gap), and relaxing the electric field concentration. The internal semiconductive layer 22 is a known semiconductive material such as a semiconductive resin material, a semiconductive rubber material, or a semiconductive tape in which a conductive material (such as conductive carbon) is mixed with a resin or rubber base material. Consists of

  The insulating layer 24 is provided for the purpose of electrical insulation. The insulating layer 24 is made of an insulating resin such as polyethylene or crosslinked polyethylene.

  The external semiconductive layer 26 is provided for the purpose of improving the adhesion with the insulating layer 24, preventing the generation of voids, and relaxing the electric field concentration. Further, it also serves as a mechanical cushioning material between the insulating layer 24 and the shielding layer 28. Similar to the internal semiconductive layer 22, the external semiconductive layer 26 is also composed of the known semiconductive material.

  The shielding layer 28 is provided for the purpose of preventing leakage of the electric field inside the cable to the outside. The shielding layer 28 is made of, for example, a tape or film of a conductive material such as a copper tape.

  The presser tape 30 is provided to fix the shielding layer 28.

  The polyethylene layer 32 is a layer mainly composed of polyethylene. Examples of the polyethylene resin include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), and ultra-low-density polyethylene (VLDPE). Very low density (polyethylene). These may be used alone or in a blend of two or more polymers. The polyethylene layer 32 may be a multilayer structure including a plurality of layers made of different types of polyethylene components. Furthermore, the polyethylene resin may be crosslinked (for example, electron beam crosslinking or thermal crosslinking).

  In the cable 1, the heat deformation amount of the polyethylene layer under the conditions of a temperature of 75 ° C. and a load of 1 kg may be less than 20%. Such a cable 1 can be suitably used as a cable having excellent heat resistance. The amount of heat deformation is more preferably 15% or less, and still more preferably 10% or less.

In the cable 1, the insulation resistance of the polyethylene layer under the conditions of a temperature of 40 ° C. and an electric field strength of 60 kV / mm may be greater than 1.0 × 10 ¹² Ω · cm. Such a cable 1 can be suitably used as a cable having excellent insulation characteristics. The insulation resistance is more preferably 1.5 × 10 ¹² Ω · cm or more, and still more preferably 1.0 × 10 ¹³ Ω · cm or more.

  The polyamide layer 34 is a layer mainly composed of polyamide (nylon). Polyamide is a homopolymer and a copolymer of polyamide having an amide group repeating unit as a main constituent in the polymer main chain. Examples of polyamides include polyamide 6 (polycaprolactam), polyamide 6,6 (polyhexamethylene adipamide), polyamide 4,6 (polytetramethylene adipamide), polyamide 6,10 (polyhexamethylene sebaca). Amide), polyamide 7 (polyenantolactam), polyamide 11 (polyundecanolactam), polyamide 12 (polydodecanolactam), and the like. These polyamides are also known by the generic name nylon. These may be used alone or in a blend of two or more polymers. The polyamide layer 34 may have a multilayer structure including a plurality of layers made of different types of polyamide components.

  The Shore D hardness of the polyamide layer 34 is 65 or more. When the Shore D hardness is 65 or more, it is possible to effectively prevent damage caused by termites. The Shore D hardness is preferably 70 or more. The Shore D hardness can be measured using a Shore hardness tester, for example, in accordance with JIS Z 2246: 2000. More specifically, the Shore D hardness can be measured by cutting out only the polyamide layer 34 from the cable 1 and using it as a measurement sample in a sheet shape. Alternatively, a Shore D hardness measurement sample is prepared by separately forming the material constituting the polyamide layer 34 into a sheet shape, the Shore D hardness of the sample is measured, and the measured value is the Shore D hardness of the polyamide layer 34. It is good also as the value of.

  At least one of the polyamide layer and the polyethylene layer is a modifier-containing layer containing a modifier. The modifier is added for the purpose of enhancing the adhesion between the polyamide layer and the polyethylene layer and suppressing the peeling of the cable, particularly the peeling when the cable is bent.

  The modifier has a melting point of 75 ° C. or higher and 115 ° C. or lower. When the modifying agent has a melting point of 75 ° C. or higher, the two layers can be directly bonded without significantly impairing the heat resistance of the cable. On the other hand, when the modifier has a melting point of 115 ° C. or lower, compatibility with the polyamide layer and the polyethylene layer is enhanced, and the effect of imparting adhesiveness by the modifier is sufficiently exhibited. The melting point is preferably 80 ° C. or higher, and preferably 105 ° C. or lower.

  The melting point of the modifier can be measured using, for example, a differential scanning calorimeter (DSC), a thermogravimetric differential thermal analyzer (TG-DTA, Thermographic-Differential Thermal Analyzer), or the like.

  The modifier contains 0.5% by mass or more and 20% by mass or less of an acid component in 100% by mass of the modifier. When the modifier contains 0.5% by mass or more of the acid component, the polyamide layer and the polyethylene layer can be directly bonded with sufficient adhesive strength. Moreover, it can suppress that durability (water resistance, heat resistance, etc.) of a cable is impaired significantly because the quantity of an acid component is 20 mass% or less. In addition, when the modifier contains 50% by mass or more of an ethylene component, compatibility with the polyethylene layer can be improved and the adhesive strength can be further improved. The amount of the acid component in the modifier is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 3% by mass or more, and particularly preferably 4% by mass or more. The amount of the acid component may be 15% by mass or less, or 10% by mass or less.

  In the present application, the “acid component” refers to a repeating unit containing an acidic group contained in a molecule of a substance such as a resin constituting the modifier. The amount of the acid component is expressed as a ratio of the acid-containing repeating unit among all the repeating units in the single or plural (co) polymers contained in the molecule of the substance constituting the modifier. For example, when the modifier is made of an ethylene / methacrylic acid copolymer (EMAA, Ethylene methacrylic acid copolymer), the total mass of ethylene-derived repeating units is E, and the total mass of repeating units derived from methacrylic acid is M. The acid component amount in EMAA is expressed as [M / (E + M)] × 100 (mass%).

  Preferable examples of the modifier include a copolymer of ethylene and an acidic comonomer having an ethylenically unsaturated group and an acid group or an acid anhydride group and copolymerizable with ethylene. Among these, a copolymer of ethylene and at least one comonomer selected from (meth) acrylic acid and (anhydrous) maleic acid is preferable. Examples of such a copolymer include ethylene / methacrylic acid copolymer (EAA), ethylene / acrylic acid copolymer (EAA), maleic acid-modified polyethylene, maleic anhydride, in addition to the above-mentioned ethylene / methacrylic acid copolymer (EMAA). Examples include modified polyethylene, ethylene / acrylic acid / maleic anhydride terpolymer, and ethylene / methacrylic acid / maleic anhydride terpolymer. Further, a modifier containing a resin (resin having an acid group in the side chain) in which an acid group-containing comonomer is grafted to the main chain mainly composed of ethylene units may be used.

The modifier contains 50% by mass or more of an ethylene component. When the modifying agent contains 50% by mass or more of an ethylene component, compatibility with the polyethylene layer can be improved and the adhesive strength can be further improved. The amount of the ethylene component is preferably 55% by mass or more. The ethylene component is a repeating unit derived from ethylene (—CH ₂ —CH ₂ —) contained in the polymer or copolymer, and the amount of the ethylene component is such that when the modifier is a single copolymer, It can obtain | require as a ratio of the mass of the repeating unit derived from ethylene with respect to the total mass of a copolymer molecule. The modifier may be a blend of an ethylene copolymer containing an acid component and polyethylene not containing an acid component. In this case, it can obtain | require as a ratio of the mass of the repeating unit derived from ethylene with respect to the total mass of all the polymers contained in a modifier.

  The modifying agent is preferably dispersed as modifying agent particles in a layer (modifying agent-containing layer) containing a modifying agent among the polyamide layer 34 and the polyethylene layer 32. FIG. 2 shows an enlarged cross-sectional view of the polyethylene layer 32 and the polyamide layer 34. In FIG. 2, the modifier particles 40 are dispersed inside the polyethylene layer 32, and the polyethylene layer 32 corresponds to the modifier-containing layer. In FIG. 2, the modifier particles 40 are dispersed only in the polyethylene layer 32, but the modifier particles 40 are dispersed in the polyamide layer 34 instead of the polyethylene layer 32 or together with the polyethylene layer 32. It may be. When the modifier is contained only in the polyamide layer 34, the polyamide layer 34 is a modifier-containing layer. When the modifier is contained in both the polyethylene layer 32 and the polyamide layer 34, the entire two layers including the polyethylene layer 32 and the polyamide layer 34 are the modifier-containing layer.

  The average particle diameter of the modifier particles 40 is preferably 1000 μm or less. By including the modifier particles 40 having such an average particle diameter, the modifier is sufficiently dispersed in the layer, and the effect of improving the adhesion between the polyamide layer 34 and the polyethylene layer 32 by the modifier is improved. It is effectively demonstrated throughout. The average particle diameter of the modifier particles 40 is more preferably 500 μm or less. Moreover, although a minimum is not specifically limited, From viewpoints, such as a handleability, it is preferable that the average particle diameter of the modifier particle 40 is 1 micrometer or more. The average particle diameter of the modifier particles 40 is obtained by magnifying the cross section of the layer containing the modifier particles 40 with a microscope such as a transmission electron microscope (TEM) and modifying the observation particle within a predetermined range of the observation drawing. The particle diameter d (refer FIG. 2) of the quality agent particle | grains 40 is calculated | required, and it can calculate as the average value. Further, the particle diameter d can be calculated as a fixed direction diameter (Feret diameter) in the above-mentioned observation drawing.

  At least one of the polyamide layer 34 and the polyethylene layer 32 may further contain an ethylene polymer other than the (co) polymer contained in the modifier. Examples of the ethylene polymer include a copolymer of ethylene and a comonomer copolymerizable with ethylene having an ethylenically unsaturated group. Specific examples of such copolymers include ethylene / methyl acrylate copolymer (EMA), ethylene / ethyl acrylate copolymer (EEA), and ethylene. / Ethylene-butyl acrylate copolymer (EBA), ethylene / acrylate copolymer, ethylene / methyl methacrylate copolymer (EMMA, Ethylene-ethyl acrylate copolymer), ethylene / ethyl methacrylate copolymer Combined (EEMA, Ethylene-Ethyl methacrylate copolymer) And ethylene / methacrylate copolymers such as ethylene / butyl methacrylate copolymer (EBMA), and ethylene / vinyl acetate copolymers (EVA) and ethylene / vinyl alcohol copolymers. And ethylene / vinyl copolymers such as (EVOH, Ethylene Vinylcopolymer). The copolymer of ethylene and a comonomer copolymerizable with ethylene having an ethylenically unsaturated group contains the comonomer to such an extent that it has sufficient heat resistance (sufficiently high melting point) required for a cable. Any copolymer can be used. These may be contained alone or in combinations of two or more.

  The polyethylene layer may contain an antifungal agent. When the polyethylene layer contains an antifungal agent, not only the damage caused by termites but also the damage caused by rats can be prevented. Examples of the antifungal agent include mouse repellents represented by capsaicin, denatonium benzoate, cycloheximide, terpenoid compounds (for example, menthol), hinokitiol and the like. These antifungal agents may be contained alone in the polyethylene layer, and may contain two or more of them. As a result, the cable 1 can be used as an ant-proof and fender-proof cable.

  In addition, each layer constituting the covering portion 20A may contain additives such as the antifungal agent, the anti-aging agent, the ultraviolet absorber, the flame retardant, the lubricant, and the reinforcing material as necessary, as long as the effects of the invention are not impaired. May be included.

[Method for manufacturing cable 1]
Although it is only an example, the cable 1 can be manufactured by the following methods, for example. First, the conductor portion 10 is formed by twisting copper wires. A semiconductive tape is wound around the outer peripheral surface of the conductor portion 10 or a semiconductive resin is extruded to form the internal semiconductive layer 22. Next, an insulating resin such as polyethylene is extruded on the outer peripheral surface of the inner semiconductive layer 22 by extrusion molding, and the insulating layer 24 is formed by crosslinking polyethylene as necessary. The outer semiconductive layer 26 is formed on the outer peripheral surface of the insulating layer 24 by disposing the same semiconductive tape or semiconductive resin as used to form the inner semiconductive layer 22. After the copper tape is wound around the outer peripheral surface of the external semiconductive layer 26 to form the shielding layer 28, the pressing tape 30 is wound around to fix the shielding layer 28.

  Next, a polyethylene layer 32 and a polyamide layer 34 are laminated on the outer peripheral surface of the presser tape 30. Here, in the cable 1, it is not necessary to provide an adhesive layer between the polyethylene layer 32 and the polyamide layer 34. Therefore, the polyethylene laminate and then the polyamide resin are heated on the outer peripheral surface of the press tape 30 while the linear laminate including the conductor portion 10 to the press tape 30 obtained as described above is conveyed in the longitudinal direction. However, the polyethylene layer 32 and the polyamide layer 34 can be laminated at a stretch by tandem extrusion molding which sequentially performs extrusion coating. Tandem extrusion can reduce production time and improve production efficiency.

  In addition, although the said manufacturing method is an example and laminated | stacked by extrusion molding about each resin layer, the method of lamination | stacking is not limited to this. For example, it can be laminated by various known methods such as a method of winding a resin film or a resin tape, a method of applying a resin and drying a film.

[cable]
The cable 1 manufactured as described above can be used in a wide range of applications for transmitting electricity, and is preferably used as a power cable. In the cable 1, the damage caused by termites is effectively prevented, and the polyamide layer and the polyethylene layer are hardly peeled even when bent. Therefore, it can be suitably used as an ant-proof cable. In particular, it can be suitably used as a power cable for embedding in the ground or arranging in a building.

(Embodiment 2)
Next, a second embodiment will be described. FIG. 3 is a schematic cross-sectional view showing a cable according to the second embodiment. Compared with the cable 1 of FIG. 1, the cable 2 of FIG. 3 is different in that the covering portion 20 </ b> B further includes an external polyethylene layer 32 b on the radially outer side of the polyamide layer 34. In the cable 2, the polyamide layer 34 is sandwiched between the inner polyethylene layer 32a and the outer polyethylene layer 32b, and the outermost layer is the outer polyethylene layer 32b.

  In the cable 2, the cable 2 is bent as compared to the case of the cable 1 in which two polyethylene layers 32 a and 32 b are arranged on both sides of the polyamide layer 34 and the polyethylene layer is arranged only on one side of the polyamide layer. In such a case, peeling is more likely to occur between the polyamide layer and the polyethylene layer. However, also in the cable 2, the adhesive force between the polyamide layer 34 and the polyethylene layer 32a or between the polyamide layer 34 and the polyethylene layer 32b is sufficient.

  Similarly to the cable 1, the polyethylene layers 32a and 32b may each contain the above-described antifungal agent. By including the antifungal agent in the polyethylene layers 32a and 32b, it is possible to prevent not only the damage caused by termites but also the damage caused by rats. As a result, the cable 2 can be used as an ant-proof and fender-proof cable.

  Polyethylene has lower water absorption than polyamide. Therefore, the cable 2 has a feature that the outer polyethylene layer 32b is the outermost layer and thus has higher water resistance than the cable 1. Polyethylene generally has higher chemical resistance than polyamide. Furthermore, the polyamide layer 34 is protected by providing the external polyethylene layer 32b. Therefore, the cable 2 having the outer polyethylene layer 32b as the outermost layer can be suitably used as a highly durable antproof cable. For example, it can be particularly suitably used as a power cable for embedment in the ground or for placement in a building.

  Next, in order to confirm the effect of the invention, the following experiment was conducted to evaluate the characteristics. The results are shown below.

(Materials used)
Each component used in the examples is as follows.
(Polyethylene layer)
PE: LLDPE (linear low density polyethylene), density 0.93, MFR 0.35, LLDPE containing 2.6% carbon

(Polyamide layer)
PA: Polyamide 12, melting point 178 ° C., density 1.20, Shore D hardness 79

(Modifier (adhesive agent))
E-EA-MAH: ethylene / acrylic acid (EA) / maleic anhydride (MAH) terpolymer EA 5% by mass, MAH 3% by mass (acid component amount in the entire copolymer: 8% by mass), MFR5, Density 0.93, melting point 107 ° C
EMAA1: ethylene / methacrylic acid copolymer, methacrylic acid amount (acid component amount) 4 mass%, MFR7, density 0.93, melting point 105 ° C.
EMAA2: ethylene / methacrylic acid copolymer, methacrylic acid amount (acid component amount) 9% by mass, MFR3, density 0.93, melting point 99 ° C.
EMAA3: ethylene / methacrylic acid copolymer, methacrylic acid amount (acid component amount) 15% by mass, MFR25, density 0.94, melting point 93 ° C.
EMAA4: ethylene / methacrylic acid copolymer, methacrylic acid amount (acid component amount) 11% by mass, MFR10, density 0.94, melting point 88 ° C., flexible type LLDPE-MAH: maleic anhydride modified linear low density polyethylene, melting point Acid-modified LLDPE containing 121 ° C., density 0.93, MFR 1.2, MAH 1.2% by mass
VLDPE-MAH: acid-modified VLDPE containing maleic anhydride-modified ultra-low density polyethylene, melting point 56 ° C., density 0.89, MFR 0.8, MAH 1.0 mass%

(Evaluation conditions)
The evaluation conditions of the items evaluated in the examples are as follows.

(Tensile shear adhesive strength)
The tensile shear adhesive force between the PE layer and the PA layer was determined by a method based on JIS K 6850 (1999).

(Heating deformation amount)
The amount of heat deformation of the PE layer was determined under the conditions of a temperature of 75 ° C. and a load of 1 kg by a method based on JIS C 3005.

(Insulation resistance)
A cable sample was prepared, and the insulation resistance was measured under the conditions of a temperature of 40 ° C. and an electric field strength of 60 kV / mm by a method based on JIS C 3005.

(Shore D hardness)
The Shore D hardness was measured using a Shore hardness tester in accordance with JIS Z 2246: 2000.

(Evaluation 1) When a polyethylene (PE) layer has a modifier According to the mixing | blending shown in Table 1, a modifier and PE resin were mixed and the PE resin mixture was prepared. A sample for evaluation was prepared using the prepared PE resin mixture and the PA, and the characteristics were evaluated. The results are shown in Table 1. In Table 1, Experiment No. 1-7 are Examples, Experiment No. 21 to 24 are comparative examples.

In addition, the following conditions were used as characteristics as characteristics necessary for use as an ant-proof cable. Those satisfying all the following criteria were judged as acceptable.
Tensile shear adhesion to PA: higher than 50 N / 150 mm ² .
Heat deformation (75 ° C., 1 kg): less than 20%.
Insulation resistance (40 ° C., 60 kV / mm): 1.0 × 10 ¹² Ω · cm or more.

  As shown in Table 1, (1) has a melting point of 75 ° C. or higher and 115 ° C. or lower, (2) has an acid component amount of 0.5% by weight or higher and 20% by weight or lower, and (3) 50% by weight or higher. When the PE layer contains the modifier containing the ethylene component, cables satisfying the above criteria were obtained (Experiment Nos. 1 to 7). Experiment No. 1 is an example of a cable having a PE layer containing 5% by mass of E-EA-MAH satisfying the above conditions (1) to (3) as a modifier. Experiment No. 2 to 5 are examples of cables having a PE layer containing 5% by mass of EMAA that satisfies the above conditions (1) to (3) as a modifier. Experiment No. 6 is 2% by mass of EMMA that satisfies the above conditions (1) to (3) as a modifier. 7 is an example of a cable having a PE layer containing 40% by mass. As can be seen from Table 1, Experiment No. Satisfactory physical properties are obtained in any of Examples 1-7. Experiment No. From the comparison of 2 to 5, it can be seen that as the acid component amount increases, the tensile shear adhesive force improves, but the heat deformation amount increases and the insulation resistance tends to gradually decrease.

  On the other hand, Experiment No. In the comparative examples shown in 21 to 24, the above criteria were not satisfied. First, Experiment No. containing no modifier. In the example of 21, it peeled without adhering between PE layer and PA layer. Experiment No. When the content of the acid-modified resin exceeded 40% by mass as in No. 22, the amount of heat deformation was large, exceeding the target reference value. In addition, the insulation resistance was low and still below the target standard. Thus, Experiment No. The cable No. 22 did not have satisfactory physical properties in terms of heat resistance and insulation characteristics.

  Experiment No. In the case of an example including a modifier having a melting point of 115 ° C. or higher (LLDPE-MAH, melting point 121 ° C.) as in 23, the tensile shear adhesive strength to PA did not satisfy the standard value. In addition, Experiment No. In the case of an example including a modifier having a melting point of 75 ° C. or lower (VLDPE-MAH, melting point 56 ° C.) as in 24, the amount of heat deformation did not satisfy the standard value, and the heat resistance was low.

(Evaluation 2) When the polyamide layer has a modifier According to the formulation shown in Table 2, the modifier and the PA resin were mixed to prepare a PA resin mixture. An evaluation sample was prepared using the prepared PA resin mixture and the PE (LLDPE), and the characteristics were evaluated. The results are shown in Table 2. In Table 2, Experiment No. 8 to 15 are Examples, Experiment No. 25 to 28 are comparative examples.

In addition, the following conditions were used as characteristics as characteristics necessary for use as an ant-proof cable. Those satisfying both of the following criteria were judged as acceptable.
Tensile shear adhesive strength to LDPE: 50 N / 150 mm ² or more Shore D hardness: 65 or more

  As shown in Table 2, (1) has a melting point of 75 ° C. or more and 115 ° C. or less, (2) has an acid component amount of 0.5% by mass or more and 20% by mass or less, and (3) 50% by mass or more. When the PA layer contains the modifier containing the ethylene component, cables satisfying the above criteria were obtained (Experiment Nos. 8 to 15).

  Experiment No. 8 is an example of a cable having a PA layer containing 5% by mass of E-EA-MAH satisfying the above conditions (1) to (3) as a modifier. Experiment No. 9 to 12 are examples of cables having a PA layer containing 5% by mass of EMAA that satisfies the above conditions (1) to (3) as a modifier. Experiment No. No. 13 is 2% by mass of EMMA satisfying the above conditions (1) to (3) as a modifier. 14 is 20% by mass. 15 is an example of a cable having a PA layer containing 40% by mass. As can be seen from Table 2, Experiment No. Satisfactory physical properties are obtained in any of Examples 8 to 15. Experiment No. From the comparison of 9 to 12, it can be seen that as the acid component amount is increased, the tensile shear adhesive force is improved, but the Shore D hardness tends to be slightly reduced.

  On the other hand, Experiment No. The comparative examples shown in 25 to 28 did not satisfy the above criteria. First, Experiment No. containing no modifier. In the example of 25, it peeled without adhere | attaching between PE layer and PA layer. Experiment No. When the content of the acid-modified resin exceeded 40% by mass as in No. 26, the standard of Shore D hardness of 65 or more was not satisfied. Such a soft layer has insufficient ant-proofing properties and is not suitable for use as an ant-proofing layer for cables.

  Experiment No. In the case of an example including a modifier having a melting point of 115 ° C. or higher (LLDPE-MAH, melting point 121 ° C.) as in 27, the tensile shear adhesive strength to PE did not satisfy the standard value. In addition, Experiment No. In the case of an example including a modifier having a melting point of 75 ° C. or lower (VLDPE-MAH, melting point 56 ° C.) as in 28, the standard of Shore D hardness of 65 or higher was not satisfied. Therefore, it is unsuitable for use as an anti-corrosion layer for cables.

  From the above results, in the cable according to the above example, at least one of the polyamide layer and the polyethylene layer contains a predetermined amount of the modifier, so that sufficient adhesion between the polyamide layer and the polyethylene layer is obtained. Is ensured, and peeling between the polyamide layer and the polyethylene layer can be suppressed. Further, it can be seen that a cable having characteristics sufficient for heat resistance and insulation properties and suitable for use as an ant-proof cable can be obtained.

  It should be understood that the embodiments and examples disclosed herein are illustrative in all respects and are not restrictive in any respect. The scope of the present invention is defined by the scope of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the scope of the claims.

  The cable of the present application can be applied particularly advantageously in a technical field where a cable having an ant-proof effect is required.

DESCRIPTION OF SYMBOLS 1 Cable 2 Cable 10 Conductor part 20A, 20B Cover part 22 Internal semiconductive layer 24 Insulating layer 26 External semiconductive layer 28 Shielding layer 30 Pressing tape 32 Polyethylene layer 32a Internal polyethylene layer 32b External polyethylene layer 34 Polyamide layer 40 Modifier particles

Claims (5)

A linear conductor part and a covering part covering the outer peripheral side of the conductor part,
The covering portion is
A polyamide layer;
A polyethylene layer bonded in contact with the polyamide layer,
At least one of the polyamide layer and the polyethylene layer is a modifier-containing layer containing a modifier,
The Shore D hardness of the polyamide layer is 65 or more,
The modifier has a melting point of 75 ° C. or higher and 115 ° C. or lower;
The modifier includes 0.5% by mass or more and 20% by mass or less of an acid component and 50% by mass or more of an ethylene component out of 100% by mass of the modifier,
The content of the modifier in the modifier-containing layer is 2% by mass to 40% by mass with respect to 100% by mass of the total mass of the modifier-containing layer.
cable. The modifier is dispersed inside the modifier-containing layer as modifier particles,
The average particle diameter of the modifier particles is 1000 μm or less,
The cable according to claim 1. The modifier is a copolymer of ethylene and at least one comonomer selected from (meth) acrylic acid and (anhydrous) maleic acid;
The cable according to claim 1 or claim 2.   The cable according to any one of claims 1 to 3, wherein an amount of heat deformation of the polyethylene layer under conditions of a temperature of 75 ° C and a load of 1 kg is less than 20%. The cable according to any one of claims 1 to 4, wherein an insulation resistance of the polyethylene layer under the conditions of a temperature of 40 ° C and an electric field strength of 60 kV / mm is more than 1.0 x 10 ¹² Ω · cm.

Images