JP7247140B2 - Wiring material and its manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a wiring material having an insulating layer made of a resin composition containing polypropylene resin, and a method for producing the wiring material.

In general, crosslinked polyethylene crosslinked with an organic peroxide is used for the insulating layer of wiring materials such as high-voltage cables so as to withstand the temperature rise of the wiring materials due to resistance heat generation of conductors. Compared to ordinary polyethylene, crosslinked polyethylene has stronger bonds between polyethylene molecular chains and is remarkably superior in heat resistance. Patent Document 1 discloses an electrical insulating composition obtained by blending a polyolefin resin such as polyethylene, a silicone compound, and an organic peroxide.
In the organic peroxide cross-linking, a mixed material containing polyethylene and an organic peroxide is extruded and coated on the outer peripheral surface of a conductor or the like, and then the polyethylene is subjected to a cross-linking reaction in a high-temperature and high-pressure cross-linking reaction tube. It takes a long time to set and stabilize the conditions of the cross-linking reaction, and maintenance of the cross-linking reaction tube is not easy, which hinders improvement of productivity.
In addition, depending on the type of organic peroxide used, a degassing step is required to remove by-products of the cross-linking reaction (for example, decomposition products of the organic peroxide), which increases production costs. Furthermore, since crosslinked polyethylene has lost its thermoplasticity, it is difficult to melt and recycle like uncrosslinked polyethylene.
On the other hand, the wiring material using the reactor blend type material as the material of the insulator layer does not require cross-linking of the material, so the cross-linking process is not required in the production of the wiring material, and the above problems when using cross-linked polyethylene are caused. It has the advantage of being excellent in productivity and manufacturing cost, and being recyclable. Therefore, a wiring material using a reactor blend type material instead of crosslinked polyethylene has attracted attention. For example, a heat-resistant wiring material has been proposed in which a resin composition containing a reactor-blend type polyolefin thermoplastic resin containing 51 to 85 mol % of crystalline polypropylene in monomer units and a random type polypropylene resin is used for an insulator layer. (Patent Document 2).

JP-A-10-12046 JP 2008-300224 A

The use of polypropylene resin instead of cross-linked polyethylene as the material for forming the insulating layer of the wiring material has been studied. This is because polypropylene can be imparted with heat resistance comparable to that of crosslinked polyethylene without being crosslinked. However, when polypropylene resin is used for the insulating layer of the wiring material, the resulting wiring material has excellent heat resistance, but is inferior in flexibility and also in molding stability. However, there is a problem that the insulator layer is deformed in the case and does not have a uniform shape).
On the other hand, high-voltage cables are required to have higher withstand voltage characteristics than ordinary insulated wires. had room for improvement.
The present invention provides a wiring material that is excellent in heat resistance, flexibility, withstand voltage characteristics, and molding stability (even if the insulator layer is formed of an uncrosslinked resin). The challenge is to In addition, an object of the present invention is to provide a method for manufacturing the wiring material, which can be manufactured without the cross-linking step required for the manufacturing method using the polyethylene.

As a result of intensive studies, the present inventors have found that a reactor blend of a polypropylene component (b1) made of polypropylene resin, homopolypropylene or random polypropylene and an ethylene-α-olefin copolymer rubber component (b2) as resin components. By adopting an insulating layer made of a resin composition containing a polyolefin thermoplastic resin (B) and a polyethylene resin in a specific amount, excellent heat resistance, flexibility and withstand voltage characteristics, and excellent molding stability can be obtained. Moreover, this wiring material is excellent in manufacturing cost, is recyclable, can be manufactured by omitting the cross-linking step that has been required in the past, and can be manufactured with high productivity. rice field. Based on this knowledge, the present inventors have conducted extensive research and have completed the present invention.

That is, the objects of the present invention have been achieved by the following means.
[1]
A wiring material having an insulating layer formed of a resin composition on the outer peripheral surface of a conductor,
The resin composition contains, in 100% by mass of the resin component,
Polypropylene resin (A) 10 to 50% by mass,
30 to 85% by mass of a reactor blend type polyolefin thermoplastic resin (B) of a polypropylene component (b1) and an ethylene-α-olefin copolymer rubber component (b2), and 5 to 25% by mass of a polyethylene resin (C)
contains
The polypropylene component (b1) consists of homopolypropylene or random polypropylene,
A wiring material in which the resin composition does not substantially contain a filler.
[2]
The reactor-blend-type polyolefin-based thermoplastic resin (B) is (i) a reactor-blend-type polyolefin-based thermoplastic resin (B-1) in which the polypropylene component (b1) is homopolypropylene, or (ii) [1], which is a mixture of the reactor-blend-type polyolefin-based thermoplastic resin (B-1) and a reactor-blend-type polyolefin-based thermoplastic resin (B-2) in which the polypropylene component (b1) is random polypropylene. wiring material.
[3]
The reactor blend type polyolefin thermoplastic resin (B) is a mixture of the reactor blend type polyolefin thermoplastic resin (B-1) and the reactor blend type polyolefin thermoplastic resin (B-2), The wiring material according to [1] or {2}, containing 40% by mass or more of the reactor-blend type polyolefin thermoplastic resin (B-1) in 100% by mass of the resin component.
[4]
The resin composition contains, in 100% by mass of the resin component, 10 to 35% by mass of the polypropylene resin (A), 55 to 80% by mass of the reactor-blend type polyolefin thermoplastic resin (B), and the polyethylene resin ( C) The wiring material according to any one of [1] to [3] containing 5 to 25% by mass.
[5]
The wiring member according to any one of [1] to [4], wherein the wiring member is an insulated wire or cable.
[6]
The wiring member according to [5], wherein the cable comprises an inner semi-conductive layer, the insulator layer, and an outer semi-conductive layer.
[7]
A method for manufacturing a wiring material having an insulating layer formed of a resin composition on the outer peripheral surface of a conductor,
10 to 50% by mass of polypropylene resin (A), 30 to 85% by mass of reactor-blend type polyolefin thermoplastic resin (B) of polypropylene component (b1) and ethylene-α-olefin copolymer component (b2), and polyethylene Covering the outer peripheral surface of the conductor with a resin composition prepared by melt-mixing 5 to 25% by mass of resin (C) in the absence of a filler,
The polypropylene component (b1) consists of homopolypropylene or random polypropylene,
A method for manufacturing a wiring material.
[8]
[7], wherein the resin composition is prepared by dry blending the polypropylene resin (A), the reactor blend type polyolefin thermoplastic resin (B), and the polyethylene resin (C), followed by melt mixing. The wiring material manufacturing method.

In the present invention, a numerical range represented using "to" means a range including the numerical values described before and after "to" as lower and upper limits.

The wiring material of the present invention is excellent in heat resistance, flexibility, withstand voltage characteristics, and molding stability. The production method of the present invention can produce the wiring material without the cross-linking step required in the production method using cross-linked polyethylene.

1 is an end view showing an example of the structure of a high-voltage cable, which is one aspect of the wiring member of the present invention; FIG.

[Wiring material]
The wiring material of the present invention has an insulator layer formed of a resin composition on the outer peripheral surface of the conductor, and the resin composition contains 10 to 50% by mass of polypropylene resin (A) in 100% by mass of the resin component, 30 to 85% by mass of a reactor blend type polyolefin thermoplastic resin (B) of a polypropylene component (b1) and an ethylene-α-olefin copolymer rubber component (b2), and 5 to 25% by mass of a polyethylene resin (C) and the polypropylene component (b1) consists of homopolypropylene or random polypropylene. The resin composition does not substantially contain a filler. A wiring material provided with this insulating layer is excellent in heat resistance, flexibility, and withstand voltage characteristics, and is excellent in molding stability during the manufacturing process.
Examples of the wiring material include insulated wires, cables, cords, optical fiber core wires, and optical fiber cords used for internal wiring or external wiring of electric/electronic devices, and insulated wires or cables are preferred. Among them, a high voltage cable is preferable.
The wiring member may have at least one insulating layer formed of the above resin composition on the outer peripheral surface of the conductor, and the rest of the configuration may be the same as the ordinary configuration of the wiring member.
The wiring material of the present invention is preferably an insulated wire. The insulated wire is an electric wire having at least one insulating layer on the outer peripheral surface of the conductor, and can be an insulated wire in which at least one of the insulating layers is an insulating layer made of the resin composition. Here, "made of an insulating resin composition" means that the insulator layer is made of a resin composition.
Usual conductors can be used as conductors, and may be single wires or twisted wires, and may be bare wires, tin-plated or enamel-coated wires. Copper, a copper alloy, aluminum, etc. are mentioned as a metal material which forms a conductor.
The insulating layer made of the resin composition may be directly provided on the outer peripheral surface of the conductor, or may be indirectly provided via another member or layer.
The thickness of the insulating layer made of the above resin composition is the same as that of ordinary wiring materials. When the wiring material is an electric wire, the thickness of the insulator layer is not particularly limited, but is usually about 0.1 to 10 mm.

The cable as the wiring material of the present invention should have at least the insulator layer formed of the above resin composition as its insulator layer, and the rest of the configuration is the same as the ordinary cable configuration. be able to. The insulator layer may be provided directly on the outer peripheral surface of the conductor, or may be provided indirectly via another member or layer.
The cable may be a cable in which an insulator layer is formed on the outer peripheral surface of a conductor or a bundle obtained by bundling a plurality of these conductors, and the insulator layer is formed of the above resin composition. In addition, the cable is a cable having an inner semiconductor layer, an insulator layer, and an outer semiconductor layer on the outer peripheral surface of the conductor or a bundle in which a plurality of these are bundled, and the insulator layer is formed of the above resin composition. can be a cable. Furthermore, it is also possible to provide a cable in which an insulating layer is formed on the outer peripheral surface of an electric wire or a bundle in which a plurality of these are bundled, and the insulating layer is formed of the above resin composition. The electric wire used in this case may have an insulator layer formed of the above resin composition.
Among cables, high-voltage cables are preferred, and the high-voltage cables preferably have an inner semiconductive layer, an insulator layer formed of the resin composition, and an outer semiconductive layer on the outer peripheral surface of the conductor. Here, the insulator layer refers to a coating layer exhibiting insulation (10 ¹² to 10 ¹⁷ Ωcm in volume resistivity measurement (JISC2139)), and the semiconductor layer refers to semiconductivity (volume resistivity measurement (JISK7194) 10 ⁰ to 10 ² Ωcm).

The conductors mentioned above can be used.
Materials commonly used for the inner semiconductive layer can be used, and preferred examples include crosslinked polyethylene, polyolefin elastomer, ethylene-based copolymers (including ethylene-octene-based copolymers), and polyolefin rubbers.
Materials commonly used for the outer semiconductive layer can be used, and preferred examples include crosslinked polyethylene, polyolefin elastomer, ethylene-based copolymer (including ethylene-vinyl acetate copolymer), and polyolefin rubber.
When the wiring material is a cable, the thickness of the insulator layer is not particularly limited, but is usually about 0.2 to 20 mm. When the wiring material is a high-voltage cable, the thickness of the insulator layer is not particularly limited, but is usually about 0.8 to 20 mm.
A preferred embodiment of a high voltage cable, shown in end view in FIG. It is a cable 101 having an insulator layer 3 covering the outer peripheral surface of the layer 2 and an outer semi-conductive layer 4 covering the outer peripheral surface of the insulator layer 3 . The insulator layer 3 is made of the above resin composition. The conductor 1, the inner semiconducting layer 2 and the outer semiconducting layer 4 are made of the above materials.

The wiring material of the present invention is excellent in molding stability during the manufacturing process. Here, the molding stability in the manufacturing process refers to the shape ( dimension) is difficult to deform, and the shape of the resin composition molded in a molten state can be maintained even after solidification (similarity between the shape of the resin composition immediately after molding and the shape of the insulating layer). This molding stability is achieved by exhibiting the property that the resin composition can maintain its shape immediately after molding, and means that an insulator layer that maintains its shape immediately after molding can be formed.
The insulator layer is usually formed through a process of coating the outer peripheral surface of the conductor or the like with a melt-mixed resin composition, followed by cooling. However, when polypropylene resin is used, the cross-sectional shape of the insulating layer may change from the shape immediately after coating (for example, from a circular shape to an elliptical shape) before the insulation layer cools. As described above, the wiring material of the present invention can form an insulator layer while suppressing such deformation of the resin composition. For this reason, the wiring material of the present invention is an insulator that maintains a predetermined molded shape immediately after molding without undergoing a step (for example, polishing, etc.) for adjusting the outer shape of the resin composition solidified on the outer peripheral surface of the conductor. have layers. The molding stability (the shape is maintained immediately after molding) of the wiring material of the present invention can be evaluated by the method described in Examples below.
The wiring material of the present invention is excellent in flexibility and heat resistance. These properties can be evaluated by the methods described in Examples.

[Resin composition]
The resin composition comprises, as resin components, a polypropylene resin (A), a polypropylene component (b1) made of homopolypropylene or random polypropylene, and an ethylene-α-olefin copolymer rubber component (b2). It contains a plastic resin (B) and a polyethylene resin (C).
The resin composition is usually a homogeneous mixture of each resin component, but the uniformity of the mixture does not matter as long as it does not impair the effects of the present invention. Moreover, when each resin component contains a plurality of constituent components, these constituent components may be present in the resin composition, and the state of existence thereof does not matter.
In this resin composition, the resin component is contained as an uncrosslinked resin.
This resin composition contains substantially no filler. Since the resin composition does not substantially contain a filler, it has excellent voltage resistance.
Here, the term "filler" refers to a filler generally used in the field of wiring materials, and includes flame retardants. In the present invention, it is preferred that the filler does not substantially contain a flame retardant.
In the present invention, substantially containing or not blending a filler means that a filler of about 0.05 parts by mass is allowed to be contained or blended with respect to 100 parts by mass of the resin composition.
Each component of the resin composition is described below.

- Polypropylene resin (A) -
The polypropylene resin (A) imparts heat resistance to the resin composition.
The polypropylene resin (A) may be a resin whose main component is a propylene component, and in addition to propylene homopolymers, random polypropylene and block polypropylene (which will be described later, corresponds to a reactor blend type polyolefin thermoplastic resin (B). (except those that do).
Here, "random polypropylene" (r-PP) refers to copolymers of propylene and ethylene and/or 1-butene.
Furthermore, "block polypropylene" (b-PP) refers to a composition (mixture) in which a rubber component is dispersed in polypropylene (homopolypropylene (h-PP) or r-PP). Block polypropylene contains 1 to 20% by mass of a rubber component. The amount of rubber component is preferably 5 to 20% by mass. Rubber components include polymers of ethylene, octene, butene, hexene, and the like. The content of the rubber component in the block polypropylene can be measured by Fourier transform infrared spectroscopy (FT-IR) or the like.
The polypropylene resin (A) preferably has a tensile modulus of 600 to 2400 MPa, more preferably 800 to 1800 MPa, as measured by the method described in JISK7161-1.
The polypropylene resin (A) preferably has a melting point of 125 to 165°C, more preferably 140 to 160°C.
The polypropylene resin (A) may be used alone or in combination of two or more.
Among heat resistance, flexibility, and molding stability, polypropylene resin (A) is preferably block polypropylene or random polypropylene from the viewpoint of emphasizing molding stability.

- Reactor blend type polyolefin thermoplastic resin (B) (reactor blend type resin (B)) -
Since the reactor blend type resin (B) has high compatibility with the polypropylene resin (A), a uniform resin composition can be obtained. As a result, when used in a specific amount, shape stability and flexibility can be imparted without significantly impairing the inherent properties of the polypropylene resin (A) such as heat resistance.
The reactor blend type resin (B) used in the present invention is not particularly limited as long as it is commonly used, but in general, at least ethylene and α-olefin are copolymerized in the presence of the polypropylene component (b1). It is a composition (mixture) in which the ethylene-α-olefin copolymer rubber component (b2) is dispersed in the polypropylene component (b1). In the reactor blend type resin (B), the polypropylene component (b1) and the ethylene-α-olefin copolymer rubber component (b2) are preferably dispersed in a state that they cannot be separated mechanically. The reactor blend type resin (B) usually contains 40 to 80% by mass of the ethylene-α-olefin copolymer rubber component (b2). The content of the ethylene-α-olefin copolymer rubber component (b2) is preferably 50 to 65% by mass, more preferably 55 to 65% by mass, in the reactor blend type resin (B). The content of the ethylene-α-olefin copolymer rubber component (b2) in the reactor blend type resin (B) can be measured by Fourier transform infrared spectroscopy (FT-IR) or the like.

In the reactor blend type resin (B), the polypropylene component (b1) consists of homopolypropylene (h-PP) or random polypropylene (r-PP). Here, consisting of homopolypropylene (h-PP) or random polypropylene (r-PP) means that the entire polypropylene component (b1) is homopolypropylene (h-PP) or random polypropylene (r-PP). Instead, it includes embodiments comprising h-PP or r-PP as part of the polypropylene component (b1).
Focusing on the polypropylene component (b1), the reactor blend type resin (B) has a form in which the polypropylene component (b1) is a homopolypropylene resin (reactor blend type resin (B-1)) and a form in which the polypropylene component (b1) is It can be classified into a form that is random polypropylene (reactor blend type resin (B-2)). The reactor blend type resin (B) may be a reactor blend type resin (B-1) or a reactor blend type resin (B-2), and the reactor blend type resin (B-1) and the reactor blend type resin (B-2) It may be a mixture with
Examples of the ethylene-α-olefin copolymer rubber component (b2) include binary copolymer rubber of ethylene and α-olefin and terpolymer rubber of ethylene, α-olefin and diene. As the α-olefin constituent, each α-olefin constituent having 3 to 12 carbon atoms is preferred. The diene component of the terpolymer rubber may be a conjugated diene component or a non-conjugated diene component, although the non-conjugated diene component is preferred. Conjugated diene constituents include, for example, constituents such as butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-1,3-butadiene, with butadiene constituents being preferred. Specific examples of non-conjugated diene constituents include constituents such as dicyclopentadiene (DCPD), ethylidene norbornene (ENB), and 1,4-hexadiene. Ethylene-propylene rubber (EPM) is preferred as the bi-copolymer rubber, and ethylene-propylene-diene rubber (EPDM) is preferred as the terpolymer rubber.

The reactor blend type resin (B) preferably has a tensile modulus of 50 to 500 MPa, more preferably 100 to 450 MPa, as measured by the method described in JISK7161-1.
The reactor blend type resin (B) preferably has a melting point of 125 to 165°C, more preferably 140 to 160°C.
The reactor blend type resin (B) is prepared by synthesizing (1) the polypropylene component (b1), and then adding ethylene and α- It can be produced by adding an olefin and, if necessary, a diene, followed by copolymerization.

- Polyethylene resin (C) -
Polyethylene resin (C) can suppress deformation after molding. In addition, since the polyethylene resin (C) has high compatibility with the polypropylene resin (A), a uniform resin composition can be obtained. As a result, when used in a specific amount, molding stability can be imparted without significantly deteriorating the inherent properties of the polypropylene resin (A) such as heat resistance.
The polyethylene resin (C) may be a resin whose main component is ethylene, and may be a homopolymer consisting only of ethylene, a copolymer of ethylene and 5 mol % or less of α-olefin (excluding propylene), and Copolymers of ethylene and 1 mol % or less of non-olefins having only carbon, oxygen and hydrogen atoms in functional groups are included (eg, JIS K 6748). As the α-olefins and non-olefins mentioned above, conventionally known copolymer components for polyethylene can be used without particular limitation.
Examples of polyethylene (PE) that can be used in the present invention include high-density polyethylene (HDPE), low-density polyethylene (LDPE), ultra-high molecular weight polyethylene (UHMW-PE), linear low-density polyethylene (LLDPE), and ultra-low density polyethylene. (VLDPE). Among these, high-density polyethylene (HDPE) is preferable from the viewpoint of maintaining heat resistance.
Polyethylene (PE) may be used individually by 1 type, and may use 2 or more types together.

- Other additives -
The resin composition can contain various additives generally used in resin compositions used for wiring materials, as long as the object of the present invention is not impaired. Examples include antioxidants and carbon black.

- Content in resin composition -
The resin composition contains 10 to 50% by mass of polypropylene resin (A), 30 to 85% by mass of reactor blend type resin (B), and 5 to 25% by mass of polyethylene resin (C) in a total of 100% by mass of the resin components. contains The total amount of polypropylene resin (A), reactor blend type resin (B), and polyethylene resin (C) is 100% by mass.
From the viewpoint of further improving flexibility and withstand voltage characteristics, the content of the polypropylene resin (A) is preferably 10 to 35% by mass in 100% by mass of the total resin components.
From the viewpoint of further improving flexibility, heat resistance, and molding stability, the content of the reactor blend type resin (B) is preferably 55 to 80% by mass in 100% by mass of the total resin components.
From the viewpoint of further improving molding stability and heat resistance, the content of the polyethylene resin (C) is preferably 5 to 20% by mass based on the total 100% by mass of the resin components.
The resin composition contains 10 to 35% by mass of polypropylene resin (A), 55 to 80% by mass of reactor blend type resin (B), and 5 to 25% by mass of polyethylene resin (C) in a total of 100% by mass of the resin components. (more preferably 5 to 20% by mass).
From the viewpoint of enhancing heat resistance, it is preferable to contain the reactor blend type resin (B-1) as the reactor blend type resin (B). More preferably, the reactor blend type resin (B-1) accounts for 50% by mass or more of the resin component.
From the viewpoint of enhancing flexibility, it is preferable to contain the reactor blend type resin (B-2) as the reactor blend type resin (B). More preferably, the reactor blend type resin (B-2) accounts for 20% by mass or more of the resin component.
From the viewpoint of heat resistance, the reactor blend type resin (B-1) is used as the reactor blend type resin (B), or the reactor blend type resin (B-1) and the reactor blend type resin (B-2) are used. and more preferably a mixture containing the reactor blend type resin (B-1) in an amount of 40% by mass or more in the resin component.

- Method for producing resin composition -
The resin composition can be produced by melt mixing the above resin components. The conditions for melting and mixing will be described in the method for manufacturing wiring members, which will be described later.

[Method for manufacturing wiring material]
The wiring material can be manufactured by a normal wiring material manufacturing method, except that the above resin composition is used for forming the insulating layer. Specifically, a method of obtaining a wiring material by forming an insulator layer by coating the outer peripheral surface of a conductor with the resin composition is mentioned.
It is as follows when the manufacturing method of a wiring material is described more concretely.
A method for manufacturing a wiring material having an insulating layer formed of a resin composition on the outer peripheral surface of a conductor,
10 to 50% by mass of polypropylene resin (A), 30 to 85% by mass of reactor blend type resin (B) of polypropylene component (b1) and ethylene-α-olefin copolymer component (b2), and polyethylene resin (C) Covering the outer peripheral surface of the conductor with a resin composition prepared by melting and mixing 5 to 25% by mass in the absence of a filler,
The polypropylene component (b1) consists of homopolypropylene or random polypropylene,
A method for manufacturing a wiring material.

In the present invention, mixing means obtaining a uniform mixture.
In the present invention, melt-mixing in the absence of a filler means melt-mixing without substantially blending a filler.
Melt-mixing conditions may be any temperature and conditions at which each resin component melts. Melt-mixing is preferably performed at a temperature of 210 to 240°C.
The mixing method is not particularly limited as long as it is a method commonly used for rubbers, plastics and the like. A single-screw extruder, a twin-screw extruder, a roll, a Banbury mixer, various kneaders, or the like can be used as a mixing device.
The mixing can be performed continuously with the coating described below, or can be performed separately after a period of time before coating.

At least part or all of the polypropylene resin (A), the reactor blend type resin (B), and the polyethylene resin (C) may or may not be dry-blended in advance. It is preferable to dry blend the polypropylene resin (A), the reactor blend type resin (B), and the polyethylene resin (C). That is, the resin composition is preferably prepared by dry blending the polypropylene resin (A), the reactor blend type resin (B), and the polyethylene resin (C), followed by melt mixing.
Dry blending may be carried out at a temperature at which each resin component does not melt, and may be carried out using a mixer, or may be carried out by mixing in a molding machine such as an extruder. Mixing in the mixer may be performed in a mixer attached to the extruder or in a mixer separate from the extruder. By performing dry blending instead of granulation, which will be described later, the withstand voltage characteristics can be further improved.

Without dry blending or after dry blending, prior to melt mixing, at least part or all of the polypropylene resin (A), the reactor blend type resin (B), and the polyethylene resin (C), It may be granulated in advance, or it may not be granulated. Here, granulation is a means adopted to increase the dispersibility of a resin component that is difficult to mix, and refers to a process of adding additives, etc., to the resin component as necessary, melt-mixing them in advance, and pelletizing them. . In the present invention, each resin component can be uniformly mixed without granulation. From the viewpoint of obtaining a wiring material having excellent withstand voltage characteristics, it is preferable not to perform granulation. In general, a granulator is equipped with a vessel for melting and mixing resin components and the like, blades that rotate within the vessel, a cutter for cutting the obtained molten mixture into pellets of a predetermined size, and the like. During melting and mixing by rotation of the blades or cutting by a cutter or the like, metal parts in the granulator may come into contact with each other to generate metal pieces, and foreign metal particles may be mixed into the resin composition. By omitting the granulation, it is possible to reduce situations in which metallic foreign matter may be mixed.

The coating can be performed continuously with the melt-mixing, or can be performed separately after an interval of time after the melt-mixing.
The method of covering the outer peripheral surface of the conductor may be any method as long as the outer peripheral surface of the conductor can be covered with the resin composition, and an appropriate molding method is applied. Examples of molding methods include extrusion molding using an extruder, injection molding using an injection molding machine, and molding using other molding machines. In the present invention, extrusion molding in which the conductor and the resin composition are co-extruded is preferred.
Extrusion can be performed using a general-purpose extruder. The extrusion molding temperature is appropriately set according to various conditions such as the type of resin and extrusion speed (take-up speed), and is preferably set to 200 to 220°C, for example.
Extrusion molding is preferable from the viewpoint of continuous production of wiring materials over a long length.

[Use of wiring material]
The wiring material of the present invention is excellent in heat resistance, flexibility, and withstand voltage characteristics. Therefore, it can be used as a wiring material for power transmission lines, communication lines, electronic devices, and automobiles. For example, it can be used as a high voltage cable for indoor wiring.

The wiring material of the present invention is excellent in heat resistance, flexibility, and withstand voltage characteristics, and is excellent in molding stability during the manufacturing process. Although the reason is not yet clear, it is considered as follows.
By using the polypropylene resin (A), the reactor blend resin (B), and the polyethylene resin (C) together in specific amounts, the polypropylene resin (A) and the reactor blend resin (B) act complementarily. Therefore, a good balance of heat resistance and flexibility can be obtained. In addition, the reactor blend type resin (B) imparts rubber elasticity, and the polyethylene resin (C) acts as a nucleus for crystallization to increase the crystallization speed by the above combined use, so that the insulating layer after molding It is possible to suppress the deformation that occurs before cooling (high molding stability). Furthermore, since the resin composition does not substantially contain a filler, dielectric breakdown is less likely to occur (high withstand voltage characteristics). As a result, it is possible to obtain a wiring material that has well-balanced heat resistance, flexibility, and withstand voltage characteristics and is excellent in molding stability in the manufacturing process.
In the case of adopting the above-described preferred form of manufacturing method, which has a step of manufacturing through dry blending without granulating the resin component, contamination of metal foreign matter is suppressed and the withstand voltage characteristics are further improved. be able to.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to these.
In Table 1, the numerical value regarding the content of each example represents % by mass.

Examples 1 to 12 and Comparative Examples 1 to 12 were carried out using the following components under the conditions shown in Table 1.

<Polypropylene resin (A)>
Block polypropylene 1: "VB170A" (trade name), manufactured by SunAllomer Co., Ltd., rubber content: 20% by mass, tensile modulus: 1100 MPa, melting point: 155°C
Homopolypropylene 1: "VA200A" (trade name, manufactured by SunAllomer)
Random polypropylene 1: "PB222A" (trade name), manufactured by SunAllomer <Reactor blend type resin (B)>
Reactor blend type resin 1: “Adflex Q200F” (trade name), manufactured by LyondellBasell, block copolymer of polypropylene and ethylene-α-olefin copolymer rubber (polypropylene component is homopolypropylene), tensile modulus of elasticity 200 MPa, melting point 155 ℃
Reactor blend type resin 2: “Adflex Q100F” (trade name), manufactured by LyondellBasell, block copolymer of polypropylene and ethylene-α-olefin copolymer rubber (polypropylene component is random polypropylene), tensile modulus of elasticity 100 MPa, melting point 145 ℃
<Polyethylene resin (C)>
Polyethylene resin 1: "Hi-Zex 5100E" (trade name), manufactured by Prime Polymer, HDPE

Crosslinking polyethylene resin 1: "NUC9060" (trade name), manufactured by NUC, LDPE
Organic peroxide 1: Permil D (trade name), manufactured by NOF Corporation, dicumyl peroxide Flame retardant 1: "SAYTEX 8010" (trade name), manufactured by Albemarle Japan, ethylenebis(pentabromophenyl)

As a wiring material having an insulating layer formed of a resin composition, the following insulated wire and three-layer cable were produced, and their characteristics were evaluated.

(Examples 1 to 10)
The polypropylene resin (A), the reactor blend type resin (B), and the polyethylene resin (C) shown in Table 1 were dry-blended in advance in another container at the mass ratio shown in Table 1 to obtain a dry blend. This dry blended product is put into an extruder (screw diameter: 25 mm), and at a screw rotation of 30 to 40 rpm and an extrusion temperature of 220 ° C., a single core conductor is placed on the outer peripheral surface of a single core conductor of 0.8 mm diameter made of bare annealed copper wire. was extruded through a die having an opening similar in shape to the outer shape of , to obtain an insulated wire having an insulating layer by extrusion coating in a circular cross-section with a thickness of about 1 mm, and water-cooling it. The resin composition is prepared by melt mixing in the extruder (hereinafter the same).

On the other hand, as a test sample for withstand voltage test measurement, the outer periphery of a multi-core conductor with a cross-sectional area of 14 mm ² consisting of seven annealed copper wires plated with an inner semi-conductive layer, an insulator layer, and an outer semi-conductive layer. A three-layer cable was formed by extrusion coating onto the surface followed by water cooling. Specifically, first, the following internal semiconductive layer composition was applied to the outer peripheral surface of the multicore conductor by an extruder (screw diameter 65 mm) at a screw rotation of 12 rpm and an extrusion temperature of 230° C. to a thickness of about 0.4 mm. Water cooling was performed after extrusion coating to form the inner semiconductor layer. Next, the dry blended product is extruded onto the internal semiconductor layer obtained above with an extruder (screw diameter 150 mm) at a screw rotation of 7 rpm and an extrusion temperature of 235 ° C. to a thickness of about 4 mm, and then water-cooled to insulate. form the body layer. Furthermore, the outer semiconductive layer composition was extruded onto the insulating layer obtained above with an extruder (screw diameter 90 mm) at a screw rotation of 6 rpm and an extrusion temperature of 240° C. to a thickness of about 0.5 mm. and cooled with water to form an external semiconductor layer.
In the above, the following composition was used for the inner semi-conductive layer.
“Plascon 100B” (trade name), manufactured by Plastrade, main component: ethylene-octene copolymer In the above, the following composition was used for the outer semiconductive layer.
"Plascon 100S" (trade name), manufactured by Plastrade, main component: ethylene-vinyl acetate copolymer

(Examples 11 and 12)
Insulation was performed in the same manner as in Example 1, except that instead of the dry blend in Example 1, a granulated product of the resin component granulated as follows was introduced into the extruder to form an insulating layer. A wire and a three-layer cable were obtained.
The granules are put into a Banbury mixer with the resin components shown in Table 1 at the mass ratio shown in Table 1, melt-mixed for 3 minutes under mixing conditions at a tank temperature of 210 ° C., and then using a pelletizer to about 5 mm square. to obtain a granule.

(Comparative example 1)
The cross-linking polyethylene resin 1 and the organic peroxide 1 are extrusion-coated on the single core conductor using the above-mentioned extruder at a screw rotation of 30 to 40 rpm and an extrusion temperature of 150 ° C. in a mass ratio shown in Table 1 to obtain an uncrosslinked coating. A body was formed, and this uncrosslinked coating was introduced into a crosslinking reaction tube (temperature: 200°C, time: 10 minutes) and crosslinked to obtain an insulated wire of Comparative Example 1.
The cross-linking polyethylene resin 1 and the organic peroxide 1 were extrusion-coated on the inner semiconductor layer using the extruder at a screw rotation of 10 rpm and an extrusion temperature of 140° C. at a mass ratio shown in Table 1 to form an uncrosslinked coating. Comparative Example 1 in the same manner as in Example 1 except that the uncrosslinked coating was introduced into a crosslinking reaction tube (temperature: 200°C, time: 10 minutes) and crosslinked to form an insulating layer. A three-layer cable was obtained.

(Comparative example 2)
An insulated wire and a three-layer cable of Comparative Example 2 were obtained in the same manner as in Example 1, except that the polypropylene resin (A) shown in Table 1 was used to form the insulator layer.

(Comparative Example 3)
An insulated wire and a three-layer cable of Comparative Example 3 were obtained in the same manner as in Example 1 except that the reactor blend type resin (B) shown in Table 1 was used to form the insulator layer.

(Comparative Examples 4-8)
In the same manner as in Example 1, except that the insulating layer was formed using the polypropylene resin (A), the reactor blend resin (B), and the polyethylene resin (C) shown in Table 1 at the mass ratio shown in Table 1. Insulated wires and three-layer cables of Comparative Examples 4 to 8 were obtained.

(Comparative Example 9)
Insulated wire of Comparative Example 9 in the same manner as in Example 1 except that the insulator layer was formed using the reactor blend type resin (B) shown in Table 1 and the polyethylene resin (C) at the mass ratio shown in Table 1. and a three-layer cable was obtained.

(Comparative Example 10)
Insulated wires of Comparative Examples 10 and 3 Got a layered cable.

(Comparative Example 11)
Comparative Example 11 was carried out in the same manner as in Example 1 except that the insulating layer was formed using the polypropylene resin (A), the reactor blend resin (B), and the flame retardant shown in Table 1 at the mass ratio shown in Table 1. of insulated wires and three-layer cables were obtained.

(Comparative Example 12)
Same as Example 1 except that the polypropylene resin (A), the reactor blend type resin (B), the polyethylene resin (C), and the flame retardant shown in Table 1 were used in the mass ratio shown in Table 1 to form the insulator layer. Then, an insulated wire and a three-layer cable of Comparative Example 12 were obtained.

The following evaluation was performed using the obtained insulated wire or three-layer cable.

- Molding stability test -
Forming stability was evaluated based on the degree of deformation of the cross-sectional shape of the insulated wire.
The insulated wire obtained above was cut perpendicularly to the longitudinal direction, and the cross section of the insulated wire was observed with a microscope. In the cross section, measure the distance between two intersections of a line segment passing through the center of the conductor and the outer circumference of the insulator layer on the opposite side of the conductor, and measure the maximum value (d1) and the minimum value (d2) asked for From this maximum value (d1) and minimum value (d2), the formula: (maximum value of the distance between two points on the outer circumference of the cross section (d1)) / (minimum value of the distance between two points on the outer circumference of the cross section ( d2)) was obtained, and the obtained value (d1/d2) was judged to be 1.06 or less.
If d1/d2 is 1.06 or less, there is little deformation of the cross-sectional shape, and there is no need to adjust the outer shape of the insulated wire when it is used for ordinary wiring materials.

-Flexibility test-
Flexibility was evaluated using tensile elongation as an index.
A single-core conductor was extracted from the insulated wire obtained above to prepare a tubular test piece having a length of 100 mm. Based on the method described in JIS C3005, a tensile test was performed with a marked line distance of 20 mm and a tensile speed of 500 mm/min, and the stress at an elongation of 100% was measured.
An evaluation of 13 MPa or less is the passing level of this test.

-Heat resistance test-
Heat deformation was measured as an index of heat resistance.
Using the insulated wire obtained above, the heat deformation rate was measured according to the method described in JIS C3005. A weight was placed so that a force of 5 N was applied at a test temperature of 150° C., and the heating time was 30 minutes.
An evaluation of 40% or less is the passing level of this test.

-anti-voltage test-
Using the three-layer cable obtained above, withstand voltage characteristics were evaluated by a withstand voltage test.
The withstand voltage test was a commercial frequency withstand voltage test. An AC voltage of 17 kV was applied to the three-layer cable for 10 minutes to confirm the presence or absence of dielectric breakdown. After that, if there was no dielectric breakdown, the voltage was increased by 10 kV and applied for an additional 30 minutes, and the operation of confirming the presence or absence of dielectric breakdown was repeated. The AC voltage applied when the dielectric breakdown occurs is defined as the dielectric breakdown voltage.
An evaluation of 77 kV or higher is the passing level of this test.

Table 1 shows the results obtained.

As is clear from Table 1, the insulated wire or three-layer cable of Comparative Example 1, which has an insulating layer made of crosslinked polyethylene on the outer peripheral surface of the conductor, required a crosslink process as a manufacturing process. The insulated wires or three-layer cables of Comparative Examples 2 to 12, which have an insulating layer formed of a resin composition that does not satisfy the resin composition specified in the present invention on the outer peripheral surface of the conductor, were subjected to a heat resistance test and a flexibility test. , withstand voltage characteristic test, and molding stability test, and was inferior in any of heat resistance, flexibility, withstand voltage characteristic, and molding stability.
On the other hand, an insulated wire or a three-layer cable having an insulating layer formed of a resin composition satisfying the composition specified in the present invention on the outer peripheral surface of the conductor is subjected to a heat resistance test, a flexibility test, and a withstand voltage characteristic. It passed both the test and the molding stability test, and has excellent heat resistance, flexibility, withstand voltage characteristics, and molding stability. As described above, the wiring material of the present invention exhibits high heat resistance and excellent flexibility while exhibiting withstand voltage characteristics necessary for a high-voltage cable. In addition, it is excellent in molding stability, and can be manufactured by omitting the step of adjusting the outer shape of the wiring material. Further, according to the method for manufacturing the wiring member of the present invention, the wiring member can be manufactured by omitting the steps of cross-linking and adjusting the outer shape of the wiring member.

101 high-voltage cable 1 conductor 2 inner semi-conductive layer 3 insulator layer 4 outer semi-conductive layer

Claims (8)

A wiring material having an insulating layer formed of a resin composition on the outer peripheral surface of a conductor,
The resin composition contains, in 100% by mass of the resin component,
Polypropylene resin (A) 10 to 50% by mass,
30 to 85% by mass of a reactor blend type polyolefin thermoplastic resin (B) of a polypropylene component (b1) and an ethylene-α-olefin copolymer rubber component (b2), and 5 to 25% by mass of a polyethylene resin (C)
contains
The polypropylene component (b1) consists of homopolypropylene or random polypropylene,
The resin composition contains substantially no filler,
wiring material. The reactor-blend-type polyolefin-based thermoplastic resin (B) is (i) a reactor-blend-type polyolefin-based thermoplastic resin (B-1) in which the polypropylene component (b1) is homopolypropylene, or (ii) 2. The mixture of the reactor blend type polyolefin thermoplastic resin (B-1) and the reactor blend type polyolefin thermoplastic resin (B-2) in which the polypropylene component (b1) is random polypropylene according to claim 1. wiring material. The reactor blend type polyolefin thermoplastic resin (B) is a mixture of the reactor blend type polyolefin thermoplastic resin (B-1) and the reactor blend type polyolefin thermoplastic resin (B-2), 3. The wiring material according to claim 2, wherein the reactor blend type polyolefin thermoplastic resin (B-1) is contained in an amount of 40% by mass or more based on 100% by mass of the resin component. The resin composition contains, in 100% by mass of the resin component, 10 to 35% by mass of the polypropylene resin (A), 55 to 80% by mass of the reactor-blend type polyolefin thermoplastic resin (B), and the polyethylene resin ( C) The wiring material according to any one of claims 1 to 3, containing 5 to 25% by mass. The wiring material according to any one of claims 1 to 4, wherein the wiring material is an insulated wire or cable. 6. The wiring material of claim 5, wherein said cable comprises an inner semi-conductive layer, said insulator layer and an outer semi-conductive layer. A method for manufacturing a wiring material having an insulating layer formed of a resin composition on the outer peripheral surface of a conductor,
10 to 50% by mass of polypropylene resin (A), 30 to 85% by mass of reactor-blend type polyolefin thermoplastic resin (B) of polypropylene component (b1) and ethylene-α-olefin copolymer component (b2), and polyethylene Covering the outer peripheral surface of the conductor with a resin composition prepared by melt-mixing 5 to 25% by mass of resin (C) in the absence of a filler,
The polypropylene component (b1) consists of homopolypropylene or random polypropylene,
A method for manufacturing a wiring material. 8. The resin composition according to claim 7, wherein the polypropylene resin (A), the reactor-blend type polyolefin thermoplastic resin (B), and the polyethylene resin (C) are dry-blended and then melt-mixed to prepare the resin composition. The wiring material manufacturing method.

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