JP7157539B2 - Wiring material - Google Patents

Description

The present invention relates to a wiring material having an aluminum conductor.

Heat resistance is required for wiring materials such as insulated wires, cables, cords, optical fiber core wires, and optical fiber cords used for internal and external wiring of electrical and electronic equipment. For example, it is formed of crosslinked polyvinyl chloride, crosslinked polyethylene). Conventionally, as such wiring materials, those having an insulating coating layer made of crosslinked polyvinyl chloride or the like on the outer periphery of a copper wire as a conductor, and those having a sheath made of crosslinked polyethylene or the like have been widely used.
CV cables (cross-linked polyethylene insulated vinyl sheath cables) with cross-linked polyethylene for the insulation coating layer and PVC resin (polyvinyl chloride) for the sheath are generally used as power cables and distribution cables.
On the other hand, from the viewpoint of scarcity of resources, cost and weight reduction, wiring materials using conductors made of aluminum (aluminum conductors) are used instead of copper conductors in electric power and power distribution fields. (see, for example, Patent Document 1).

JP 2017-143645 A

However, aluminum has a lower electrical conductivity than copper, so the diameter of the conductor must be thicker to allow the same current to flow. Furthermore, aluminum conductors are hard and have many problems such as being easily broken if scratched. A CV cable using such an aluminum conductor becomes hard when wired, so that the cable may bounce during wiring, making it difficult to wire (less flexible).
In addition, in conventional CV cables, it is difficult to peel the insulating coating layer from the conductor, and in particular, CV cables using aluminum conductors, which have the above problem, are required to be improved in stripping processability. In other words, the aluminum conductor is easily damaged during the peeling process, and there is a risk that the aluminum conductor will break if the process is not carried out carefully. In addition, in the peeling process, linear bodies or hair-like bodies (sometimes referred to as whiskers) of the insulating coating layer and cut shavings may remain on the cut end surface of the insulating coating layer. If such whiskers or cut shavings remain, the whiskers will bite into the connector during connector processing, resulting in poor contact.
In addition, since the aluminum conductor is very vulnerable to scratches, the blade cannot be used to cut into the insulating coating layer. Conventional cross-linked polyethylene cannot be peeled unless the blade is sufficiently inserted, and even in that case, whiskers tend to remain. This whisker must be removed in post-processing. Therefore, if the coating is stripped without inserting the blade too much, the productivity is greatly improved.

The present invention combines high heat resistance with excellent flexibility and peelability (also called ease of processing when peeling the insulating coating layer, peelability) even when an aluminum conductor is used as the conductor. An object of the present invention is to provide a wiring material.

The present inventors have found that an insulating coating layer provided directly on the outer periphery of an aluminum conductor (without providing an adhesive layer or the like) is formed by a grafting reaction of a specific amount of a silane coupling agent on ethylene rubber or a styrene-based elastomer. By forming with a silanol condensation cured product obtained by curing by silanol condensation of a silane coupling agent for a specific silane crosslinkable composition containing a silane graft resin, a specific amount of an inorganic filler and a silanol condensation catalyst, It was found that the resulting wiring material can be imparted with excellent flexibility, peelability and heat resistance. Based on this knowledge, the present inventors have made further studies and completed the present invention.

That is, the objects of the present invention have been achieved by the following means.
<1> A wiring material having at least one insulating coating layer on the outer periphery of an aluminum conductor,
A wiring material in which the innermost insulating coating layer directly provided on the outer circumference of the aluminum conductor among the insulating coating layers is made of a silanol condensation cured product of the following silane crosslinkable composition.
<Silane crosslinkable composition>
100 parts by mass of a base resin containing at least one of ethylene rubber and styrene elastomer, 10 to 400 parts by mass of an inorganic filler, and 1 to 15.0 parts by mass of a silane coupling agent grafted to the base resin. and <2> the wiring material according to <1>, wherein the base resin contains an organic mineral oil.
<3> The wiring material according to <1> or <2>, wherein the total content of the ethylene rubber and the styrene elastomer in the base resin is at least 5% by mass.
<4> The wiring material according to any one of <1> to <3>, wherein the inorganic filler contains at least one selected from the group consisting of metal hydrates, silica, calcium carbonate and clay.
<5> The wiring member according to any one of <1> to <4>, wherein the insulating coating layer has two or more layers, and the outermost insulating coating layer is a polyvinyl chloride insulating coating layer.

In this specification, the numerical range represented by "to" means a range including the numerical values before and after "to" as lower and upper limits.

The wiring material of the present invention, even if an aluminum conductor is used as the conductor, combines high heat resistance with excellent flexibility and peelability, and can also achieve weight reduction.

[Wiring material]
The wiring material of the present invention has at least one insulating coating layer on the outer periphery of the aluminum conductor. Of the at least one insulation coating layer (hereinafter sometimes simply referred to as a coating layer), the innermost insulation coating layer provided directly on the outer periphery of the aluminum conductor is formed of a silanol condensation cured product of the following silane crosslinkable composition. It is
-Silane crosslinkable composition-
100 parts by mass of a base resin containing at least one of ethylene rubber and styrene elastomer, 10 to 400 parts by mass of an inorganic filler, and 1 to 15.0 parts by mass of a silane coupling agent grafted to the base resin. and a silane crosslinkable composition further containing a silanol condensation catalyst

In the silane-crosslinkable composition, containing a base resin and a silane coupling agent grafted to the base resin means, for example, that the base resin (including at least one of ethylene rubber and styrene-based elastomer) has a silane The aspect containing the Silang graft resin formed by a coupling agent graft-reacting is mentioned.
This silane crosslinkable composition contains 100 parts by mass of a base resin containing at least one of ethylene rubber and styrene elastomer, 0.01 to 0.6 parts by mass of an organic peroxide, and 10 to 400 parts by mass of an inorganic filler. , and 1 to 15 parts by mass of a silane coupling agent having a site capable of grafting reaction and a site capable of grafting reaction (referred to as a grafting reaction site) of the base resin at a temperature equal to or higher than the decomposition temperature of the organic peroxide. A silane graft in which the silane coupling agent is bonded to the base resin in the form of a graft chain by a covalent bond or the like by melt-kneading and causing a grafting reaction between the base resin and the silane coupling agent by means of radicals generated from the organic peroxide. A mixture of a silane masterbatch obtained as a reaction composition (melt-kneaded product) containing a resin (also referred to as a silane crosslinkable resin) and a condensation catalyst masterbatch containing a silanol condensation catalyst is preferred.

In the present invention, "provided directly on the outer circumference of the aluminum conductor" means that the outer circumference of the aluminum conductor is in contact with the outer circumference of the aluminum conductor without an adhesive layer, a primer layer, or another layer such as an insulating coating layer interposed therebetween. means that it is set with

A wiring material having an aluminum conductor and an innermost insulating coating layer formed of the silanol condensation cured product of the silane crosslinkable composition of the present invention has high heat resistance, excellent flexibility, and peelability. Although the details of the reason are not yet clear, it is considered as follows.
That is, the crosslinked polyethylene coated on the outside of the aluminum conductor, which is a conventional structure, is integrated with the aluminum conductor, thereby increasing the hardness of the aluminum conductor. Moreover, since the aluminum conductor has a smaller conductor resistance and a smaller allowable current than the copper conductor, it is usually increased in size (increased in diameter), so that the wiring material itself becomes hard. Furthermore, the crosslinked polyethylene layer is hard and difficult to insert with a blade, and since the material stretches, it cannot be peeled unless a blade is inserted into the vicinity of the conductor.
However, in the wiring material of the present invention, the portion (innermost insulating coating layer) in direct contact with the aluminum conductor is formed from the silanol condensation cured product of the silane crosslinkable composition, thereby reducing the hardness of the aluminum conductor. Also, it is possible to reduce the repulsion of the wiring material against the stress acting during wiring. In addition, it is possible to process the aluminum conductor while suppressing the damage of the aluminum conductor and the remaining of whiskers and cut shavings. Specifically, when cutting the coating layer, the coating layer can be peeled off (cut or removed) without leaving whiskers or cutting shavings even if the blade is not inserted to the limit of the aluminum conductor. Furthermore, the silanol condensation cured product of the silane crosslinkable composition has excellent short-term heat resistance (for example, against instantaneous temperature rise in the environmental atmosphere) and is difficult to melt, and long-term (for example, continuously or intermittently in the environmental atmosphere). It is also possible to improve the heat resistance (against a typical high temperature), and it is possible to reduce the diameter of the wiring material. Moreover, since aluminum has a small specific gravity, it is possible to reduce the weight of the wiring material provided with the copper conductor.

Since the wiring material of the present invention exhibits excellent peelability, it is a wiring material before being peeled (unpeeled), and the coating layer can be formed as desired due to the excellent peelability. is the wiring material after the is removed (skinned).

The insulated wire that can be used as the wiring material of the present invention may be an electric wire having at least one insulating coating layer on the outer periphery of the aluminum conductor, and the aluminum conductor may be a single wire or an aluminum stranded wire described later.
The cable that can be used as the wiring material of the present invention usually has two or more insulating coating layers on the outer periphery of the aluminum conductor, and the outermost insulating coating layer ( The outermost insulating coating layer) surrounds the aluminum conductor and other insulating coating layers. For example, there is a cable in which one or a plurality of insulated wires having an innermost insulating coating layer on the outer circumference of an aluminum conductor are collectively surrounded by an outermost insulating coating layer called a sheath. When this cable has a plurality of insulated wires, the plurality of insulated wires may be arranged in parallel, or may be arranged in a twisted manner (stranded wire). When twisting the insulated wires, the number of insulated wires, the arrangement of the insulated wires, the twisting direction, the twisting pitch, and the like can be appropriately set according to the application.

The diameter of the wiring material can be appropriately determined according to the application and the like, and is not particularly limited. For example, when used as an insulated wire, the thickness is preferably 0.8 to 35 mm, more preferably 1 to 30 mm, in terms of strength and flexibility. When used as a cable, the thickness is preferably 0.8 to 50 mm, more preferably 1 to 35 mm, in terms of strength and flexibility.

The wiring material of the present invention is mainly used as a substitute electric wire or cable for a CV cable, which is a power distribution cable, and is also suitable for cabtyre cables, cords, railway cables, solar and wind power generation cables, and aircraft cables. be done.

<Aluminum conductor>
The aluminum conductor used in the present invention is not particularly limited as long as it is a conductor made of aluminum. It is also called.).

As the aluminum wire, those conventionally used for wiring materials can be used, and for example, a wire made of (pure) aluminum or an aluminum alloy can be used. Examples of aluminum alloys include, but are not limited to, 1000 series aluminum alloys, 2000 series aluminum alloys, 3000 series aluminum alloys, 4000 series aluminum alloys, 5000 series aluminum alloys, and 6000 series aluminum alloys. , Fe is 0.6% by mass or less, Si is 0.2 to 1.0% by mass, Mg is 0.2 to 1.0% by mass, and the balance is aluminum and inevitable impurities. be done.
Among aluminum and aluminum alloys, 1000 series aluminum alloys having an aluminum purity of 99% or more are preferable, and those having high electrical conductivity are preferable.
The cross-sectional shape of the aluminum wire can be appropriately determined according to the application, and examples thereof include round (circular), flat (rectangular), hexagonal, and the like. In the present invention, a circular cross-section is preferred, for example, because it facilitates the formation of a stranded wire.

The number of aluminum wires forming the stranded wire is not particularly limited as long as it is plural (two or more).
The arrangement, twisting direction, twisting pitch, and the like of the aluminum wires when the aluminum wires are twisted can be appropriately set according to the application.
In order to reduce the outer diameter of the stranded aluminum wire, it is preferable to use a rolled conductor that is further drawn by a die or the like after being stranded.

The outer diameter of the aluminum wire can be appropriately determined according to the application, etc., but in terms of strength and flexibility, it is preferably 0.15 to 3.5 mm, more preferably 0.3 to 3 mm, and 0.3 mm to 3 mm. 0.35 to 2.5 mm is more preferred.
The outer diameter of the aluminum stranded wire can be appropriately determined according to the application and the like. preferable. The outer diameter of the stranded aluminum wire is the diameter of an imaginary circumscribed circle circumscribing the outer peripheral surfaces of the plurality of aluminum wires arranged on the outer side in a cross section perpendicular to the axis of the stranded wire.
The outside diameter of the stranded wire and the cross-sectional area of the conductor are determined by the allowable current. From this point of view, the wire diameter is particularly preferably about 0.3 to 1 mm.

<Insulating layer>
The insulating coating layer provided on the outer periphery of the aluminum conductor functions as an insulating layer and has a single-layer structure or a multi-layer structure.
When the insulating coating layer is a single layer, this insulating coating layer becomes the innermost insulating coating layer provided in direct contact with the outer circumference of the aluminum conductor.
On the other hand, when the insulating coating layer has a multi-layer structure (referred to as a multi-layer insulating coating layer), the number of constituent layers constituting the multi-layer insulating coating layer can be appropriately determined according to the application. , preferably 2 to 5 layers, more preferably 2 or 3 layers. In particular, when the wiring material is a cable, the insulating coating layer is preferably a multiple insulating coating layer, and the outermost insulating coating layer in the multiple insulating coating layers functions as a sheath. In the multilayer insulating coating layer, it is preferable that the constituent layers are directly laminated without interposing another layer such as an adhesive layer.

In the present invention, for convenience, a wiring material having a single insulating coating layer (innermost insulating coating layer) is referred to as an insulated wire, and a wiring material having a multilayer insulating coating layer, particularly an outermost insulating coating layer (sheath) is referred to as a cable. However, as described above, even an insulated wire includes a form having a multilayer insulation coating layer.

In the present invention, when layers formed of the same material (ingredients and content) are laminated to form the insulating coating layer, these layers are counted as one layer. On the other hand, even if the material forming the insulating coating layer is the same material, if they are not laminated adjacently, that is, if they are laminated via another layer, each layer is counted as one layer. do. Also, when layers formed of different materials forming the insulating coating layer are stacked, each layer is counted as one layer regardless of whether or not they are adjacent.

- Innermost insulating coating layer -
The innermost insulating coating layer (hereinafter sometimes referred to simply as the innermost coating layer) is a layer of a silanol condensation cured product (sometimes referred to as a cured product layer) formed by subjecting a silane crosslinkable composition to a silanol condensation reaction. formed by This cured product layer can be formed, for example, using a silane crosslinkable composition by the method described below.

The cured material layer, which will be described later in detail, contains a silane graft resin obtained by grafting a specific amount of a silane coupling agent to a base resin containing ethylene rubber or a styrene elastomer resin, and a specific amount of an inorganic filler. The silane crosslinkable composition is crosslinked by hydrolyzing the hydrolyzable groups of the silane coupling agent bonded to the silane graft resin, followed by a silanol condensation reaction. This cured product layer is a layer made of a silane-crosslinked product obtained by silane-crosslinking at least one of the ethylene rubber and the styrene-based elastomer among the resins contained in the base resin via a silane coupling agent. The ethylene rubber and styrene-based elastomer to be silane-crosslinked may be the total amount or a part of the ethylene rubber and styrene-based elastomer used, and can be appropriately determined depending on the application. If at least one of ethylene rubber and styrene-based elastomer contains silane-crosslinked product, silane-crosslinked product contains cross-linked product obtained by silane-crosslinking resin other than ethylene rubber and styrene-based elastomer with other resin. It doesn't have to be.

- Outermost insulating coating layer -
The outermost insulating coating layer (simply referred to as the outermost coating layer or surface layer) is made of a known resin used for wiring materials, and examples thereof include thermoplastic resins and thermosetting resins described later.

- Intermediate insulating coating layer -
When the insulating coating layer is a multi-layer insulating coating layer having three or more layers, the intermediate insulating coating layer provided between the innermost coating layer and the outermost coating layer is made of a known resin used for wiring materials, Examples thereof include thermoplastic resins and thermosetting resins, which will be described later.

- Thickness of insulating coating layer -
The thickness of the insulating coating layer can be appropriately determined according to the diameter of the wiring material, the application, and the like. For example, the total thickness of the coating layer (in the case of a multi-layer coating layer, the total thickness of each component layer) is preferably 0.2 to 10 mm, and 0.2 to 10 mm in terms of heat resistance, dielectric strength, strength and flexibility. 6 to 5 mm is more preferred.
The thickness of each constituent layer can also be appropriately determined according to the total thickness of the coating layers, the diameter of the wiring material, the application, and the like. For example, the thickness of the innermost insulating coating layer is preferably 0.2 to 5 mm, more preferably 0.5 to 4 mm, when used as an electric wire, and preferably 0.4 to 5 mm, when used as a cable. , 0.5 to 3 mm. In the present invention, the thickness of the innermost coating layer is the difference (the thinnest thickness) between the outer diameter of the aluminum conductor and the outer diameter of the innermost coating layer. The thickness of the outermost coating layer is, for example, preferably 0.2 to 5 mm, more preferably 0.5 to 4 mm. The (total) thickness of the intermediate insulating coating layer is preferably 0 to 5 mm, for example.

[Method for manufacturing wiring material]
First, each component used in the method of manufacturing the wiring material will be described.
<Aluminum conductor>
A commercially available aluminum conductor may be used as the aluminum conductor used in the present invention. The aluminum stranded wire may be produced by twisting commercially available aluminum wires by a known method.

<Base resin>
The base resin used in the present invention contains at least one of ethylene rubber and styrene elastomer. Ethylene rubber and styrene-based elastomers have, in the presence of radicals generated from organic peroxides described below, a site capable of undergoing grafting reaction with a silane coupling agent in the main chain or at the end thereof. there is Examples of sites that can be grafted include unsaturated bond sites of carbon chains, carbon atoms having hydrogen atoms, and the like. By containing at least one of ethylene rubber and styrene-based elastomer in the base resin, the balance with the strength of the aluminum conductor can be improved.
This base resin may contain other resins and, if necessary, other resins, organic mineral oils, plasticizers, and the like.

(ethylene rubber)
Ethylene rubber is not particularly limited as long as it is a copolymer rubber of ethylene and α-olefin. For example, ethylene rubber is preferably a binary copolymer rubber of ethylene and α-olefin (preferably having 1 to 12 carbon atoms), ethylene and α-olefin (preferably having 1 to 12 carbon atoms) and α- A rubber composed of a terpolymer with a third component having an unsaturated bond other than an olefin may be mentioned. The third component includes conjugated or non-conjugated dienes, specifically butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, dicyclopentadiene (DCPD), ethylidene norbornene (ENB), 1,4-hexadiene and the like. Binary copolymer rubbers include ethylene-propylene rubber (EPM), and terpolymer rubbers include ethylene-propylene-diene rubber (EPDM).
Ethylene rubber may be used alone or in combination of two or more.

(Styrene-based elastomer)
Styrene-based elastomers refer to those having an aromatic vinyl compound as a constituent component in the molecule. Examples of such styrene-based elastomers include block copolymers and random copolymers of conjugated diene compounds and aromatic vinyl compounds, or hydrogenated products thereof. Examples of such styrene-based elastomers include styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), hydrogenated SIS, styrene-butadiene-styrene block copolymer. polymer (SBS), hydrogenated SBS, styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-butadiene rubber (SBR), Examples include hydrogenated styrene-butadiene rubber (HSBR).
Styrenic elastomers may be used alone or in combination of two or more.

(other resin)
Other resins that may be contained in the base rubber are not particularly limited, but polyolefin resins are preferable in that a silane coupling agent, which will be described later, can undergo a grafting reaction.
The polyolefin resin is a resin composed of a homopolymer or copolymer of a compound having an ethylenically unsaturated bond, and is grafted with a silane coupling agent in the presence of radicals generated from an organic peroxide to be described later. A polymer resin having a reactive site and a site capable of grafting reaction in the main chain or at its end is preferred.
As such a polyolefin-based resin, those used in conventional heat-resistant resin compositions can be used without particular limitation. For example, resins such as polyethylene, polypropylene, ethylene-α-olefin copolymer, polyolefin copolymer having an acid copolymerization component (including an acid ester copolymerization component), rubbers or elastomers of these polymers, etc. is mentioned. The rubber or elastomer may be anything other than ethylene rubber and styrene elastomer, and examples thereof include copolymer rubber of alkyl acrylate and ethylene (ethylene acrylic rubber). Among them, resins such as polyethylene, polypropylene, ethylene-α-olefin copolymers, and polyolefin copolymers having an acid copolymer component are preferred.
In particular, polyethylene is preferable as another resin to be used in combination with ethylene rubber, and polyethylene, a resin of a polyolefin copolymer having an acid copolymerization component, and the like are preferable as other resins to be preferably used in combination with a styrene-based elastomer.
The polyolefin-based resin and each resin described below may be used alone or in combination of two or more.

- Polyethylene resin -
The polyethylene resin may be a polymer resin containing an ethylene component, and may be an ethylene homopolymer or a copolymer of ethylene and an α-olefin (preferably 5 mol % or less) (excluding polypropylene). ), and resins composed of copolymers of ethylene and non-olefins (preferably 1 mol % or less) having only carbon, oxygen and hydrogen atoms in functional groups. As the α-olefins and non-olefins mentioned above, known ones conventionally used as copolymerization components of polyethylene can be used without particular limitation.
Polyethylene resins include high density polyethylene (HDPE), low density polyethylene (LDPE), ultra high molecular weight polyethylene (UHMW-PE), linear low density polyethylene (LLDPE) and very low density polyethylene (VLDPE). Among them, low density polyethylene, linear low density polyethylene or ultra-low density polyethylene is preferable, and low density polyethylene or linear low density polyethylene is more preferable.

- Polypropylene resin -
The polypropylene resin may be a polymer resin containing propylene as a main component, such as a propylene homopolymer (homopolypropylene resin), an ethylene-propylene random copolymer, an ethylene-propylene block copolymer, and the like. can be used.

- Ethylene-α-olefin copolymer resin -
Ethylene-α-olefin copolymer resins preferably include resins of copolymers of ethylene and α-olefins having 3 to 12 carbon atoms (excluding those corresponding to the polyethylene and polypropylene described above). .

- Polyolefin copolymer resin having an acid copolymer component -
The acid copolymerization component (including the acid ester copolymerization component) in the polyolefin copolymer resin having an acid copolymerization component is not particularly limited, but may be a carboxylic acid compound such as (meth)acrylic acid, vinyl acetate, or Examples include acid ester compounds such as alkyl (meth)acrylates (preferably having 1 to 12 carbon atoms). Polyolefin copolymer resins having an acid copolymer component include, for example, ethylene-vinyl acetate copolymer (EVA), ethylene-(meth)acrylic acid copolymer, ethylene-alkyl(meth)acrylate copolymer, and the like. each resin of. Among them, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-butyl acrylate copolymer are preferable, because of their acceptability to inorganic fillers and heat resistance. Ethylene-vinyl acetate copolymer resin is more preferable from the viewpoint of properties.

The polyolefin resin may be acid-modified. The acid used for acid modification is not particularly limited, and commonly used unsaturated carboxylic acids and the like can be mentioned.

Examples of other resins include acrylic rubbers, polyester elastomers, polyamide elastomers, etc., in addition to the above polyolefin resins.

(organic mineral oil)
Organic mineral oils include aromatic oils, paraffinic oils, naphthenic oils, or mixed oils containing these three. As the organic mineral oil, those commonly used in resin compositions can be used without particular limitation, and paraffinic oils and naphthenic oils are preferred. One type of organic mineral oil may be used alone, or two or more types may be used in combination.

- Base resin content -
The total content of ethylene rubber and styrene elastomer in the base resin is not particularly limited as long as it exceeds 0% by mass, preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. . The lower limit of the total content is preferably 100% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less.
The content of ethylene rubber or styrene-based elastomer in the base resin is appropriately set within a range that satisfies the above total content. For example, the content of ethylene rubber or styrene elastomer is preferably 5 to 40% by mass, more preferably 10 to 30% by mass. The content of the styrene-based elastomer is preferably 20% by mass or more from the viewpoint of peelability (suppression of whiskering).

The total content of the polyolefin resin in the base resin is not particularly limited, but is preferably 0 to 85% by mass, more preferably 10 to 70% by mass.
In the present invention, the content of each resin included in the polyolefin resin in the base resin is appropriately set within a range that satisfies the above content of the polyolefin resin. For example, the content is set as follows. be done.
The polyethylene resin content is preferably 0 to 30% by mass. The polypropylene resin content is preferably 0 to 35% by mass, more preferably 0 to 20% by mass. The content of the ethylene-α-olefin copolymer resin is preferably 10 to 85% by mass. The content of the polyolefin copolymer resin having an acid copolymer component is preferably 0 to 60% by mass, more preferably 0 to 40% by mass.

The content of the resin other than the polyolefin-based resin among the other resins in the base resin can be appropriately set within a range that does not impair the effects of the present invention.
The content of the organic mineral oil in the base resin (when the base resin contains a plasticizer, the total content with the plasticizer) is not particularly limited, but is preferably 0 to 40% by mass.

<Inorganic filler>
The inorganic filler used in the present invention is not particularly limited as long as it is commonly used in conventional resin compositions. It is preferable to have a site that can be chemically bonded by an intermolecular bond. Examples of sites that can be chemically bonded to hydrolyzable silyl groups include OH groups (OH groups such as hydroxyl groups, water molecules containing water or water of crystallization, and carboxyl groups), amino groups, SH groups, and the like.
Examples of inorganic fillers include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whiskers, and hydrated aluminum silicate. , hydrated magnesium silicate, basic magnesium carbonate, hydrotalcite, talc, and other compounds having a hydroxyl group or water of crystallization. Boron nitride, silica (crystalline silica, amorphous silica, etc.), carbon, clay, zinc oxide, tin oxide, titanium oxide, molybdenum oxide, antimony trioxide, silicone compounds, quartz, zinc borate, white carbon, Also included are zinc borate, zinc hydroxystannate, zinc stannate and the like.
The inorganic filler preferably contains at least one selected from the group consisting of metal hydrates, silica, calcium carbonate and clay, more preferably at least one selected from this group.

The inorganic filler can also be used after being surface-treated with various surface-treating agents. Examples of magnesium hydroxide surface-treated with a silane coupling agent include Kisuma 5L and Kisuma 5P (both trade names, manufactured by Kyowa Chemical Industry Co., Ltd.).
An inorganic filler may be used individually by 1 type, and may use 2 or more types together.

When the inorganic filler is used as a powder, the average particle size is preferably 0.2 to 10 μm, more preferably 0.3 to 8 μm, even more preferably 0.4 to 5 μm, 0.4 to 3 μm is particularly preferred. When the average particle size of the inorganic filler is within the above range, it is possible to obtain a molded article having an appearance free of lumps by preventing secondary aggregation, and the bonding with the silane coupling agent is maintained to achieve sufficient cross-linking. can be formed. The average particle size of the inorganic filler is determined by dispersing the inorganic filler in alcohol or water and using an optical particle size analyzer such as a laser diffraction/scattering particle size distribution analyzer.

<Organic Peroxide>
The organic peroxide used in the present invention generates radicals by at least thermal decomposition, and serves as a catalyst for grafting reaction of the silane coupling agent to the base resin by radical reaction (grafting reaction site of the silane coupling agent and base resin). It is a covalent bond forming reaction with a graftable site of the resin, which is also called a (radical) addition reaction.). For example, when the silane coupling agent contains an ethylenically unsaturated group as a grafting reaction site, a grafting reaction (including a hydrogen radical abstraction reaction from the base resin) between the ethylenically unsaturated group and the base resin ( binding).
The organic peroxide is not particularly limited as long as it performs the above functions. For example, compounds represented by the general formula: R ¹ -OO-R ² , R ³ -OO-C(=O)R ⁴ or R ⁵ C(=O)-OO(C=O)R ⁶ are preferred. Here, R ¹ to R ⁶ each independently represent an alkyl group, an aryl group or an acyl group. Among R ¹ to R ⁶ of each compound, it is preferable that all of them are alkyl groups, or that one of them is an alkyl group and the rest are acyl groups. As such organic peroxides, those used in radical polymerization or conventional silane cross-linking methods can be used without particular limitation, and include benzoyl peroxide, dicumyl peroxide, 2,5-dimethyl-2, 5-di-(tert-butylperoxy)hexane or 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexyne-3 are preferred.

The decomposition temperature of the organic peroxide is preferably 80 to 195°C, particularly preferably 125 to 180°C. In the present invention, the decomposition temperature of an organic peroxide refers to the temperature at which an organic peroxide of a single composition, when heated, causes itself to decompose into two or more compounds within a certain temperature or temperature range. means. Specifically, it refers to the temperature at which heat absorption or heat generation starts when heated from room temperature at a heating rate of 5° C./min in a nitrogen gas atmosphere by thermal analysis such as DSC method.
One type of organic peroxide may be used, or two or more types may be used.

<Silane coupling agent>
The silane coupling agent used in the present invention is a site capable of grafting reaction to a site capable of grafting reaction of ethylene rubber, styrene elastomer or polyolefin resin in the presence of radicals generated by decomposition of organic peroxide. (group or atom) and a hydrolyzable silyl group capable of silanol condensation is not particularly limited. Examples of such a silane coupling agent include silane coupling agents used in conventional silane cross-linking methods.

Examples of such a silane coupling agent include silane coupling agents having an ethylenically unsaturated group as a graftable site. Specifically, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, vinylsilanes such as silane, vinyldimethoxyethoxysilane, vinyldimethoxybutoxysilane, vinyldiethoxybutoxysilane, allyltrimethoxysilane, allyltriethoxysilane, vinyltriacetoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, (Meth)acryloxysilane such as methacryloxypropylmethyldimethoxysilane and the like. Among them, vinyltrimethoxysilane or vinyltriethoxysilane is particularly preferred.
One type of silane coupling agent may be used, or two or more types may be used.
The silane coupling agent may be used as it is or diluted with a solvent.

<Silanol condensation catalyst>
The silanol condensation catalyst used in the present invention causes (promotes) the silanol condensation reaction of the silane coupling agent grafted to the base resin in the presence of water. Based on the action of this silanol condensation catalyst, the polyolefin resin is crosslinked via the silane coupling agent. As a result, a silane-crosslinked resin molded article having excellent heat resistance can be obtained.
Such silanol condensation catalysts are not particularly limited, and examples thereof include organotin compounds, metallic soaps, platinum compounds and the like. Specifically, organic tin compounds such as dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctiate, dibutyltin diacetate, zinc stearate, lead stearate, barium stearate, calcium stearate, sodium stearate, lead naphthenate, sulfuric acid Examples include lead, zinc sulfate, and organoplatinum compounds. Organotin compounds are preferred.
One type of silanol condensation catalyst may be used, or two or more types may be used.

<Carrier resin>
In the present invention, the silanol condensation catalyst may be used as it is, or may be used as a mixture with a resin (condensation catalyst masterbatch). The resin to be melt-kneaded (supported) with the silanol condensation catalyst (referred to as a carrier resin) is not particularly limited, but the polyolefin-based resins described above for the base resin can be used. A polyethylene resin is preferable because it has a high affinity with a silanol condensation catalyst and can impart high heat resistance. One type of carrier resin may be used, or two or more types may be used.

<Additive>
Various additives can be used in the present invention. Examples of additives include various additives generally used in wiring materials and the like. Examples of such additives include antioxidants, cross-linking aids, lubricants, metal deactivators, flame retardants (auxiliaries), and resins other than the above polyolefin resins.
As the antioxidant, those commonly used in conventional heat-resistant resin compositions can be used without particular limitation, and examples thereof include benzimidazole antioxidants, amine antioxidants, and phenol antioxidants , sulfur-based antioxidants, hydrazine-based antioxidants, and the like.

<Method for manufacturing wiring material>
The wiring material of the present invention is not particularly limited. It is preferably produced by a production method comprising the step (d) of disposing on the outer peripheral surface of the conductor and the step (e) of bringing the silane crosslinkable composition into contact with water to crosslink it.
Each step will be described below.

(Silane masterbatch preparation step (a))
The silane masterbatch contains 0.01 to 0.6 parts by mass of an organic peroxide, 10 to 400 parts by mass of an inorganic filler, and 1 to 15 parts by mass of a silane coupling agent having a graft reaction site is melt-kneaded (melt-mixed) at a temperature equal to or higher than the decomposition temperature of the organic peroxide, and radicals generated from the organic peroxide are added to the base resin. A reaction composition containing a silane graft resin can be prepared by grafting a silane coupling agent.

In this preparation step (a), the base resin includes an aspect in which the entire amount (100 parts by mass) is blended and an aspect in which a part of the base resin is blended. When a part of the base resin is blended, the remainder of the base resin may be blended in any step other than the step (a), but is preferably blended in the condensation catalyst masterbatch preparation step (b ). When part of the base resin is blended in the preparation step (a), 100 parts by mass of the base resin in the preparation step (a) means the base resin blended in the preparation step (a) and the base resin blended in other steps. It means the total amount of blending with.
When a part of the base resin is blended in the preparation step (a), the base resin blended in the preparation step (a) preferably accounts for 55 to 99% by mass, more preferably 60 to 95% by mass, based on the total amount. %, and the amount of the base resin added in other steps, particularly the preparation step (b), is preferably 1 to 45% by mass, more preferably 5 to 40% by mass, based on the total amount.

In this preparation step (a), the amount of the organic peroxide compounded is 0.01 to 0.6 parts by mass with respect to 100 parts by mass of the base resin. By setting the amount of the organic peroxide within the above range, the grafting reaction can be performed in an appropriate range, and the silane masterbatch (silane graft resin composition) having excellent extrudability by suppressing the occurrence of pimples can be prepared. The blending amount of the organic peroxide is preferably 0.05 to 0.3 parts by mass, more preferably 0.07 to 0.25 parts by mass.

In the preparation step (a), the amount of the inorganic filler compounded is preferably 10 to 400 parts by mass, more preferably 30 to 280 parts by mass, based on 100 parts by mass of the base resin. By setting the amount of the inorganic filler to be within the above range, the grafting reaction of the silane coupling agent becomes uniform, and high heat resistance and excellent appearance can be imparted to the cured silanol condensation product of the silane crosslinkable composition. The amount of the inorganic filler to be blended is preferably less than 100 parts by mass from the viewpoint of peelability (remaining cut scum).

In the preparation step (a), the amount of the silane coupling agent compounded is 1 to 15 parts by mass with respect to 100 parts by mass of the base resin. By setting the amount of the silane coupling agent to be blended within the above range, high heat resistance and excellent appearance can be imparted to the silanol condensation cured product. The amount of the silane coupling agent to be blended is preferably 3 to 12 parts by mass, more preferably 4 to 12 parts by mass.

In the preparation step (a), the mixing order of each component is not particularly limited, and the components may be mixed in any order. Although each component can be melt-kneaded at once, it is preferable to melt-knead each component by the following steps (a-1) and (a-2).
Step (a-1): Step of mixing at least an inorganic filler and a silane coupling agent to prepare a mixture Step (a-2): The mixture obtained in Step (a-1) and all or part of the base resin and melt-kneading in the presence of an organic peroxide at a temperature equal to or higher than the decomposition temperature of the organic peroxide

In step (a-1), the method for mixing the inorganic filler and the silane coupling agent is not particularly limited, and wet mixing or dry mixing may be used. In the present invention, dry mixing (dry blending) in which the silane coupling agent is mixed with the inorganic filler with or without heating is preferred. By this process, the surface (site that can be chemically bonded) is bonded or adsorbed with a silane coupling agent with a strong bond (via a hydrolyzable silyl group that can be silanol-condensed), and the silane coupling agent with a weak bond on the surface. An inorganic filler to which a ring agent is bound or adsorbed can be prepared. Weak bonds include interactions due to hydrogen bonds, interactions between ions, partial charges or dipoles, actions due to adsorption, etc. Strong bonds include chemical bonds with sites that can be chemically bonded on the surface of the inorganic filler. etc. This makes it possible to reduce volatilization of the silane coupling agent in the step (a-2) and the like, and to prepare or produce a highly heat-resistant cured product and wiring material.
The mixing conditions in step (a-1) are performed at a temperature lower than the decomposition temperature of the organic peroxide, and the above components are mixed while suppressing the occurrence of the grafting reaction. The mixing temperature is preferably 10 to 60° C., more preferably room temperature (25° C.), and can be set for several minutes to several hours. For this mixing, a commonly used mixer, for example, the kneading device described in step (a-2) can be used.
In step (a-1), a base resin may be present as long as the temperature is maintained below the decomposition temperature. In this case, it is preferable to mix the inorganic filler and the silane coupling agent together with the base resin at the above temperature (step (a-1)) and then melt-knead the mixture.

Next, the mixture obtained in step (a-1), all or part of the base resin, and the remaining components not mixed in step (a-1) are combined with an organic Melt and knead at a temperature above the decomposition temperature of the peroxide. As a result, radicals generated from the organic peroxide cause a grafting (bonding) reaction between the grafting reaction site of the silane coupling agent and the graftable site of the base resin. In ethylene rubbers and styrene elastomers, the grafting reaction of a silane coupling agent normally proceeds selectively (preferentially) with respect to polyolefin resins and the like. Therefore, in the steps (a) and (a-2), even if a polyolefin resin or the like coexists, a silane-grafted resin (silane-grafted ethylene rubber and silane-grafted styrene-based elastomer) are obtained.
In steps (a) and (a-2), the temperature at which the above components are melt-kneaded is the decomposition temperature of the organic peroxide or higher, preferably the decomposition temperature of the organic peroxide + (25 to 110)°C. , for example at a temperature of 150-230°C. Other melt-kneading conditions, such as mixing time, can be appropriately set. As a result, the organic peroxide decomposes, acts on the silane coupling agent, and the grafting reaction of the silane coupling agent to the base resin proceeds.
The kneading method is not particularly limited as long as it is a method commonly used for rubbers, plastics and the like. A kneading device is appropriately selected according to, for example, the amount of the inorganic filler. For example, single-screw extruders, twin-screw extruders, rolls, Banbury mixers or various kneaders may be used. Among them, closed mixers such as Banbury mixers and various kneaders are preferable from the standpoint of resin dispersibility.
A method of mixing the base resin is not particularly limited. For example, the base resin may be prepared in advance and then mixed, or each component, for example, resin components such as ethylene rubber and styrene elastomer, organic mineral oil, etc., may be separately mixed.

The organic peroxide may be present when performing step (a-2), and may be mixed in step (a-1) or mixed in step (a-2). When mixing an organic peroxide, the mixing temperature is kept below the decomposition temperature of the organic peroxide.

In the present invention, the above components can be melted and kneaded at once. In this case, it is preferable to melt-knead the above components after dry-blending them in advance. As the method and conditions for dry blending and melt kneading, the methods and conditions described in steps (a-1) and (a-2) can be employed. Step (a-2) can be performed continuously with step (a-1).

Step (a), particularly step (a-2), is preferably carried out in the absence of a silanol condensation catalyst to suppress the condensation reaction of the silane coupling agent. In the present invention, melt-kneading in the absence of a silanol condensation catalyst means melt-kneading without substantially blending a silanol condensation catalyst. In other words, it does not exclude the presence of a silanol condensation catalyst that is inevitably present, and means that it may be present to the extent that the following kneadability and moldability problems due to silanol condensation of the silane coupling agent do not occur. do. For example, the silanol condensation catalyst may be present in an amount of 0.01 parts by mass or less with respect to 100 parts by mass of the resin composition. By performing the melt-kneading in the absence of a silanol condensation catalyst, it is possible to suppress the condensation reaction of the silane coupling agent, excellent kneadability (easy melt-kneading), and excellent moldability (desired shape can be extruded into
In step (a), the amount of other resins and additives that can be used in addition to the above components is appropriately set within a range that does not impair the object of the present invention.

In the preparation step (a), particularly the above step (a-1), the silane coupling agent binds or adsorbs to the chemically bondable site of the inorganic filler with its hydrolyzable silyl group. Furthermore, in the preparation step (a), particularly step (a-2), the silane coupling agent is grafted with a graftable site of ethylene rubber, styrene elastomer or polyolefin resin at its grafting reaction site. chemical reaction. In the step (a), the silane coupling agent is grafted onto the base resin at least as follows. That is, it is a mode in which the silane coupling agent bound or adsorbed to the inorganic filler by a weak bond desorbs from the inorganic filler and undergoes a grafting reaction with the base resin. Moreover, it is a mode in which the silane coupling agent bonded or adsorbed to the inorganic filler with a strong bond undergoes a grafting reaction to the base resin while maintaining the bond with the inorganic filler.

Thus, the base resin and the silane coupling agent are subjected to a grafting reaction to synthesize a silane graft resin, and a silane masterbatch (also referred to as silane MB) containing this silane graft resin as a reaction composition is prepared. be. In this grafting reaction, one molecule of the silane coupling agent is usually added to one graftable site, but the present invention is not limited to this. This silane MB (a) is a reaction composition containing a silane-grafted resin obtained by grafting a silane coupling agent to a base resin to an extent that it can be molded by the step (d) described later.

(Preparation step (preparation step) of condensation catalyst masterbatch)
In the wiring material manufacturing method, a preparation step (preparation step) of the condensation catalyst masterbatch is performed. Specifically, a silanol condensation catalyst and a carrier resin are melt-kneaded to prepare a condensation catalyst masterbatch (condensation catalyst MB). The melt-kneading of the carrier resin and the silanol condensation catalyst may be carried out under the condition that the carrier resin is molten. This melt-kneading can be performed in the same manner as the melt-kneading in the preparation step (a). For example, the kneading temperature can be set to 80-250°C, more preferably 100-240°C. Other conditions such as the kneading time can be appropriately set.

When part of the base resin is melt-kneaded in the preparation step (a), it is preferable to use the remainder of the base resin as the carrier resin. In this case, the blending ratio of the remainder of the resin composition and the silanol condensation catalyst is as described above. As the carrier resin, resins other than the base resin can be used. In this case, the amount of the carrier resin compounded is preferably 1 to 60 parts by mass, more preferably 2 to 50 parts by mass, and even more preferably 2 to 40 parts by mass with respect to 100 parts by mass of the base resin.
Furthermore, the condensation catalyst MB may contain an inorganic filler. The content of the inorganic filler in the condensation catalyst MB is not particularly limited, but is preferably 350 parts by mass or less with respect to 100 parts by mass of the carrier resin. If the amount of filler is too large, the silanol condensation catalyst may be difficult to disperse, and the silanol condensation reaction may be difficult to proceed. On the other hand, if the amount of the carrier resin is too large, the degree of cross-linking of the molded product may decrease, and the desired heat resistance may not be obtained.
In the preparation step (b), only the silanol condensation catalyst may be prepared (used alone) without melt-kneading the silanol condensation catalyst with the carrier resin.

(Preparation step (c) of silane crosslinkable composition)
In the wiring material manufacturing method, the silane MB and the condensation catalyst MB are then melt-kneaded to prepare a silane crosslinkable composition.
The amount of the silanol condensation catalyst is not particularly limited, but is preferably 0.01 to 0.6 parts by mass, more preferably 0.001 to 0.4 parts by mass, per 100 parts by mass of the base resin. When the blending amount of the silanol condensation catalyst is within the above range, the cross-linking reaction due to the silanol condensation reaction of the silane coupling agent tends to progress almost uniformly, and the heat resistance of the silanol condensation cured product can be enhanced. Furthermore, it is possible to prevent appearance roughness and deterioration of physical properties, and improve productivity.

The melt-kneading in the preparation step (c) may be any method as long as it is performed while the base resin is molten. For example, it can be performed in the same manner as the melt-kneading in the preparation step (a). °C, more preferably 100 to 240°C. The preparation step (c) is performed while suppressing the silanol condensation reaction of the coupling agent grafted onto the base resin. For example, the preparation step (c) is preferably carried out under conditions where the amount of water present is small, and it is preferred that the silane MB and the silanol condensation catalyst are not kept in a kneaded state at a high temperature for a long time.
Before melt-kneading in the preparation step (c), each MB can be mixed, for example, dry-blended while the base resin or carrier resin is not melted. The dry blending method and conditions are not particularly limited, and examples thereof include the dry blending in step (a-1) and its conditions.
In the preparation step (c), the condensation catalyst MB is used, but in the wiring material manufacturing method of the present invention, instead of the condensation catalyst MB, the silanol condensation catalyst alone may be melt-kneaded into the silane MB. can.

Thus, a silane crosslinkable composition, which is a melt-kneaded product of the silane MB and the condensation catalyst MB, is obtained. This silane crosslinkable composition contains a silane crosslinkable resin and a silanol condensation catalyst. This silane crosslinkable composition (silane crosslinkable resin) is an uncrosslinked body in which the hydrolyzable silyl groups derived from the silane coupling agent are not silanol-condensed. Practically, partial cross-linking (partial cross-linking) is unavoidable due to the melt-kneading in the preparation step (c), but it is preferable that the moldability in the step (d) described below is maintained.

(Step (d) of disposing the silane crosslinkable composition on the outer peripheral surface of the aluminum conductor)
In the method for manufacturing the wiring material, the step (d) of disposing the silane crosslinkable composition on the outer peripheral surface of the aluminum conductor is then performed. In this step (d), the silane crosslinkable composition is usually formed into the shape of the innermost coating layer of the wiring material and placed on the outer peripheral surface of the aluminum conductor.
The method for molding the silane crosslinkable composition is not particularly limited as long as it can be molded into the shape of the innermost coating layer, and may be extrusion molding using an extruder, extrusion molding using an injection molding machine, or other molding. Examples include a molding method using a machine, and an extrusion molding method in which the aluminum conductor is extruded simultaneously with the aluminum conductor 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 base resin or carrier resin and the extrusion speed (take-up speed), and is preferably set to 80 to 250°C, for example.
The step (d) is carried out while suppressing the silanol condensation reaction of the silane coupling agent in the same manner as the step (c).

The melt-kneading in step (c) and the molding in step (d) can be performed simultaneously or consecutively. That is, as one embodiment of melt-kneading, for example, a mode of melt-kneading molding materials (silane MB and condensation catalyst MB) during or immediately before extrusion molding can be mentioned. For example, as a continuous method, a silane crosslinkable composition obtained by mixing (dry blending) a silane MB and a condensation catalyst MB at normal temperature or high temperature (in a non-melting state) is introduced into a molding machine and melt-kneaded. method. Alternatively, the silane MB and the condensation catalyst MB may be melt-kneaded and pelletized, and then introduced into a molding machine and melt-kneaded again. More specifically, a series of steps of melt-kneading a silane-crosslinkable composition of a silane MB and a condensation catalyst MB in a coating device, then extruding and coating the outer peripheral surface of a conductor or the like to form a desired shape. can be adopted.
As described above, the silane crosslinkable composition molded into the shape of the innermost coating layer can be placed on the outer peripheral surface of the aluminum conductor. The silane crosslinkable composition (silane crosslinkable resin) is uncrosslinked as described above.

(Step (e) of contacting the silane crosslinkable composition with water to crosslink it)
In the method for producing the wiring material, the silane crosslinkable composition (molded body) placed on the outer peripheral surface of the aluminum conductor is then brought into contact with water. As a result, the hydrolyzable silyl group of the silane coupling agent is hydrolyzed by water to form a silanol (OH group bonded to a silicon atom), and the silanol condensation catalyst present in the silane crosslinkable composition causes the hydroxyl groups of the silanol to (Dehydration) condensation occurs and a cross-linking reaction occurs (silanol condensation cure of the silane-crosslinkable composition is formed).
Step (e) can be carried out by conventional methods. The condensation reaction proceeds in the presence of a silanol condensation catalyst simply by storage at room temperature. Therefore, it is not necessary to actively bring the silane crosslinkable composition into contact with water. In order to promote this condensation reaction, the silane crosslinkable composition and water can be brought into active contact. Examples of methods for positive contact with water include immersion in water (warm water), introduction into a moist heat bath, exposure to high-temperature steam, and the like. Also, at that time, pressure may be applied to permeate the moisture inside.

In this way, a wiring material is produced in which the innermost coating layer comprising the silanol condensation cured product of the silane crosslinkable composition is provided on the outer periphery of the aluminum conductor.
The silanol condensation cured product of the silane crosslinkable composition is a silane graft resin obtained by grafting a specific amount of a silane coupling agent to a base resin containing ethylene rubber or a styrene elastomer, and a silane containing a specific amount of an inorganic filler. About a crosslinkable composition, the hydrolyzable group of the silane coupling agent couple|bonded with the silane graft resin is bridge|crosslinked by silanol condensation. The silane-grafted resin contains at least one of a silane-grafted ethylene rubber and a silane-grafted styrene-based elastomer, and includes a silane-grafted resin obtained by grafting a silane coupling agent to a resin other than the ethylene rubber and the styrene-based elastomer. You can stay. In the silanol condensation cured product, the silane graft resin forms a crosslinked resin condensed via a silanol bond (siloxane bond). The inorganic filler may be bound to the silane coupling agent of the silane graft resin. In the silane crosslinkable composition and silanol condensation cured product, the ethylene rubber and styrene elastomer are not crosslinked with other resins.
Therefore, this cured product layer contains a crosslinked cured product of a silane-grafted resin (silane-grafted ethylene rubber and a silane-grafted styrene-based elastomer) and an inorganic filler. The crosslinked cured product of the silane graft resin has base resin constituents (ethylene rubber constituents, styrene elastomer constituents, polyolefin constituents), inorganic filler constituents, and silane coupling agent constituents. The content of each component in the cured product layer varies depending on the reaction conditions, the reaction rate, etc., but is preferably within the above range. More specifically, the cured product layer includes a silane graft resin bonded or adsorbed to an inorganic filler by a silane coupling agent, and a crosslinked resin bonded (crosslinked) via an inorganic filler and a silane coupling agent, and a silane graft The reaction site of the silane coupling agent grafted to the resin (silane-grafted ethylene rubber and silane-grafted styrene-based elastomer) hydrolyzes and undergoes a silanol condensation reaction with each other, thereby cross-linking the silane-grafted resins via the silane coupling agent. and at least a silane crosslinked resin. Moreover, each of the crosslinked resin and the silane crosslinked resin may have a mixture of bonding (crosslinking) via the inorganic filler and the silane coupling agent and crosslinking via the silane coupling agent.

When the wiring member has multiple coating layers, the wiring member can be manufactured by sequentially forming the required number of constituent layers (intermediate insulating coating layer and outermost coating layer) on the outer peripheral surface of the innermost coating layer.
Materials for forming the constituent layers are not particularly limited as long as they are commonly used for wiring materials, and organic resins are preferred. Examples of organic resins include various thermoplastic resins and thermosetting resins. For example, in addition to the base resins described above, polyvinyl chloride, polyamide, polyphenylene sulfide (PPS), polyetherketone (PEK), polyaryl Ether ketone (PAEK), tetrafluoroethylene/ethylene copolymer (ETFE), polyether ether ketone (including PEEK and modified PEEK), polyether ketone ketone (PEKK), polyethylene terephthalate (PET), polyamideimide (PAI) ), polyimide (PI), polyester (PEst), polyurethane, polyester elastomer, polyolefin elastomer, polyamide elastomer, fluororesin, fluororubber, acrylic rubber, and the like. An organic resin may be used individually by 1 type, or 2 or more types may be used for it. The organic resin may contain various commonly used additives.
As the method for forming the constituent layer with an organic resin, any ordinary method can be applied without particular limitation, and examples thereof include extrusion molding of an organic resin, coating and baking of an organic resin varnish, and the like.
Among the constituent layers, the outermost coating layer is preferably made of polyvinyl chloride. Polyvinyl chloride forming the outermost coating layer is more preferably soft polyvinyl chloride. For example, 35 to 70 parts by weight of a commonly used plasticizer and 20 to 100 parts by weight of an inorganic filler are added to 100 parts by weight of polyvinyl chloride. and a PVC composition containing
The method of forming the constituent layers is the same as the method of arranging the base resin or resin composition around the outer periphery of the aluminum conductor.

In the wiring material manufacturing method, other resins and additives that can be used in addition to the above components may be kneaded or mixed in any step, and the order of mixing in each step is not particularly limited. In the production method of the present invention, the amount of the additive to be added is not particularly limited, and can be appropriately set within a range that does not impair the intended effect. The blending amount of the antioxidant can be appropriately set, but is preferably 0.1 to 15.0 parts by mass, more preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the resin composition.

Specifically, the method for producing the wiring material of the present invention has the following preparation step (a), preparation step (c), arrangement step (d), and cross-linking step (e), provided that the following preparation When the condensation catalyst MB is used in step (c), it further has a preparatory step (b).
Preparation step (a): 0.01 to 0.6 parts by mass of an organic peroxide and 10 to 400 parts by mass of an inorganic filler with respect to 100 parts by mass of a base resin containing at least one of ethylene rubber and styrene elastomer , 1 to 15 parts by mass of a silane coupling agent having a site capable of grafting reaction of the base resin and a site capable of grafting reaction, at a temperature equal to or higher than the decomposition temperature of the organic peroxide, preferably without the silanol condensation catalyst. A process preparatory step (b) for preparing a silane MB containing a silane graft resin by melt-kneading in the presence of a silane coupling agent and grafting the silane coupling agent onto the base resin by means of radicals generated from the organic peroxide: silanol A step of melt-kneading a condensation catalyst and a carrier resin, preferably in the absence of a silanol condensation catalyst, to prepare a condensation catalyst MB Preparation step (c): Melt-kneading a silane MB and a silanol condensation catalyst or a condensation catalyst MB Placement step (d): A step of placing the silane crosslinkable composition obtained in the preparation step (c) on the outer peripheral surface of the aluminum conductor Crosslinking step (e): The silane crosslinkable composition placed on the outer peripheral surface of the aluminum conductor The step of contacting the composition with water For each step in the above production method, further, the reaction in the silane crosslinking method and the form of the condensed cured product obtained, for example, the description of JP-A-2017-145370 can be applied as appropriate. , the content described in this publication is taken in as it is as part of the description of the present specification.

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to these.
In Tables 1 to 3, the numerical values relating to the compounding amounts in each example represent parts by mass unless otherwise specified. A blank column for each component means that the amount of the corresponding component is 0 parts by mass.

Details of each component (compound) shown in Tables 1 to 3 are shown below.
<Base resin>
- Ethylene rubber -
Mitsui EPT0045H: trade name, EPM, Mitsui Chemicals Co., Ltd. Nodel 3720P: trade name, EPDM (ethylene-propylene-ethylidene norbornene rubber), manufactured by Dow Chemical Company - styrene elastomer -
Septon 4077: trade name, SEEPS, manufactured by Kuraray Tuftec (registered trademark) N504: Hydrogenated SEBS (styrene/ethylene-butylene ratio = 32/68, manufactured by Asahi Kasei Corporation)
Septon 4033: trade name, SEEPS, manufactured by Kuraray Co., Ltd. Kraton 1901FG: trade name, maleic acid-modified styrene-based elastomer, manufactured by Kraton Japan - polyolefin resin -
Evolue SP1540: trade name, LLDPE, manufactured by Prime Polymer)
NUC7540: trade name, LLDPE, manufactured by Nihon Unicar PB222A: trade name, polypropylene (ethylene-propylene random copolymer resin), manufactured by SunAllomer NUC6520: trade name, ethylene-ethyl acrylate copolymer resin, manufactured by Nihon Unicar Co., Ltd. EV360 : Evaflex EV360 (trade name), ethylene-vinyl acetate copolymer, manufactured by DuPont Mitsui Polychemicals -organic mineral oil-
Diana Process PW-90: trade name, paraffin oil, manufactured by Idemitsu Kosan <Inorganic filler>
Aerosil 200: trade name, hydrophilic fumed silica, Kisuma 5L manufactured by Nippon Aerosil Co., Ltd.: trade name, silane coupling agent surface-treated magnesium hydroxide, Softon 1200 manufactured by Kyowa Chemical Industry Co., Ltd.: trade name, calcium carbonate, Bihoku Funka Kogyo Co., Ltd. Glowmax LL manufactured by Co., Ltd.: trade name, Karion clay (calcined Karion), <Silane coupling agent> manufactured by Takehara Chemical Industry Co., Ltd.
KBM-1003: trade name, vinyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd. <organic peroxide>
Perhexa 25B: trade name, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, decomposition temperature 179°C, manufactured by NOF <Antioxidant>
Irganox 1010: trade name, manufactured by BASF, pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate]
<Silanol condensation catalyst>
ADEKA STAB OT-1: trade name, dioctyltin dilaurate, manufactured by ADEKA <PVC mixture>
SHV9877P: Product name, PVC compound: Hardness 80A, manufactured by Riken Technos

In Examples 1 to 10 and Comparative Examples 4 to 6, of 100% by mass of the base resin, part (95% by mass) was used in the preparation step (a), and the remainder (5% by mass) was used in the preparation step (b). Used as a carrier resin.

<Implementation of step (a) and step (b)>
(Examples 1 to 10 and Comparative Examples 3 to 7)
The silane coupling agent and the organic peroxide were mixed at 25°C in the amounts shown in the column of Silane MB in Tables 1 to 3, and then the inorganic filler and antioxidant were added and mixed at 30°C. . Next, the obtained mixture and the base resin in the compounding amounts shown in the silane MB column of Tables 1 to 3 were put into a Banbury mixer and melted and kneaded at 120 to 200 ° C. for 10 minutes. C. and passed through a feeder ruder to obtain silane MB pellets (step (a)).
The silane grafting reaction was caused by melt-kneading in the Banbury mixer.
On the other hand, for Examples 1 to 10 and Comparative Examples 4 and 6, the carrier resin, the silanol condensation catalyst and the antioxidant were put into a Banbury mixer at the blending amounts shown in the condensation catalyst MB column of Tables 1 to 3, and 170 After melt kneading at 180° C., the materials were discharged at a discharge temperature of 180° C. and passed through a feeder ruder to obtain pellets of the condensation catalyst MB (step (b)).
For Comparative Examples 3, 5 and 7, no condensation catalyst MB was prepared.
(Comparative example 1)
Silane MB pellets were obtained in the same manner as in the above example, except that the organic peroxide, silane coupling agent and silanol condensation catalyst were not used.
(Comparative example 2)
Components other than the organic peroxide shown in Table 3 were put into a Banbury mixer, melted and kneaded at 170°C, discharged at a material discharge temperature of 180°C, passed through a feeder ruder, and pellets were obtained. After that, the roll temperature was set to 90° C., and after kneading the above pellets, a predetermined amount of organic peroxide was mixed to obtain a mixed roll sheet, and further pellets were obtained by applying a square pelletizer.

<Implementation of preparation step (c), arrangement step (d) and cross-linking step (e)>
(Examples 1, 3 to 9, Comparative Examples 4 and 6)
Next, the pellets of the silane MB and the pellets of the condensation catalyst MB thus prepared were dry-blended at the compounding ratios shown in Tables 1 to 3.
The resulting dry blend was introduced into an extruder equipped with a screw having a diameter of 40 mm (ratio of screw effective length L to diameter D: L/D = 24, compression section screw temperature 190°C, head temperature 200°C). did. While melt-kneading the dry blend (preparing the silane crosslinkable composition) in this extruder (preparation step (c)), it is directly extruded on the outer peripheral surface of a 1/0.8 mm aluminum conductor with a thickness of 1 mm as a conductor. (arrangement) to obtain a thin covered conductor having an outer diameter of 2.8 mm (arrangement step (d)).
Separately, the obtained dry blended product was extruded with a screw having a diameter of 90 mm (ratio of screw effective length L to diameter D: L / D = 28, compression part screw temperature 190 ° C., head temperature 200° C.). While melt kneading the dry blend (preparing a silane crosslinkable composition) in this extruder (preparation step (c)), 38 SQ (19/1.6) (conductor diameter 7.3 mm) aluminum as a conductor A thick coated conductor having an outer diameter of 9.7 mm was obtained by extruding (arranging) directly on the outer peripheral surface of the stranded wire with a thickness of 1.2 mm (arranging step (d)).
The obtained two types of coated conductors (small-diameter covered conductor and large-diameter covered conductor) were left in an atmosphere at a temperature of 60° C. and a relative humidity of 95% for 24 hours and brought into contact with water (crosslinking step (e )).
In this way, two types of aluminum conductor wires (small-diameter insulated wire and large-diameter insulated wire) having a single-layer coating layer (innermost coating layer) were produced.

(Examples 2 and 10)
For Examples 2 and 10, large-diameter insulated wires having a single-layer covering layer were produced as described above.
On the other hand, for the small-diameter insulated wire, the outermost coating layer (sheath) was formed on the outer peripheral surface as follows to manufacture a cable having two coating layers. That is, in the same manner as in the production of the aluminum conductor wire of Example 1, the preparation step (c), the arrangement step (d) and the cross-linking step (e) were carried out to produce an aluminum conductor wire (small diameter insulated wire). . An extruder equipped with a screw having a diameter of 90 mm on the outside of the obtained aluminum conductor wire (ratio of screw effective length L to diameter D: L / D = 28, compression part screw temperature 170 ° C., head temperature 180 ° C.) was supplied with a PVC resin mixture to cover the outside of the aluminum conductor insulated wire with the PVC resin mixture to form a sheath layer with a layer thickness of 2 mm. In this way, a cable with a two-layer coating having an outer diameter of 6.8 mm was produced.
In Tables 1 and 2, when a sheath was formed, "PVC resin mixture" in the tables was described as "use".

(Comparative Examples 1, 3, 5, 7)
A small-diameter covered conductor and a large-diameter covered conductor were obtained in the same manner as in the arrangement step (d) of Example 1, except that only silane MB was used in the arrangement step (d) of Example 1.
The obtained two types of coated conductors (thin-diameter coated conductor and large-diameter coated conductor) were brought into contact with water in the same manner as in the cross-linking step (e) in the examples to form a single-layer coating layer (innermost coating layer). Two types of aluminum conductor wires (small-diameter insulated wires and large-diameter insulated wires) were manufactured.

(Comparative example 2)
The pellets obtained in the above step (b) are extruded with a screw having a diameter of 65 mm (ratio of screw effective length L to diameter D: L / D = 22, compression part screw temperature 70 ° C., head temperature 90 ° C. ), and then passed through a steam bridge pipe adjusted to 200 ° C. and 4.5 atmospheres to directly extrude (arrange) on the outer peripheral surface of a 1/0.8 mm aluminum conductor with a thickness of 1 mm as a conductor, A thin coated conductor with an outer diameter of 2.8 mm was obtained.
Separately, the obtained dry blended product was extruded with a screw having a diameter of 115 mm (ratio of screw effective length L to diameter D: L / D = 24, compression part screw temperature 70 ° C., head temperature 80° C.). After that, by passing through a steam bridge pipe adjusted to 200 ° C. and 3.5 atmospheres, a 38SQ (19/1.6) (conductor diameter 7.3 mm) aluminum stranded wire as a conductor has a thickness of 1.2 mm on the outer peripheral surface. to obtain a large-diameter coated conductor having an outer diameter of 9.7 mm. In Comparative Example 2, the small-diameter covered conductor and large-diameter covered conductor thus obtained were combined with aluminum conductor wires (small-diameter insulated wire and large-diameter insulated wire) each having a single-layer coating layer (innermost coating layer). did.

The manufactured insulated wires were evaluated as follows, and the results are shown in Tables 1 to 3.
<Workability test>
(Cutting property test of insulated wire)
The stripping workability of the insulated wire was evaluated by a cutting test based on the following tests.
- 1. Presence/absence of beard generation confirmation test -
A thin insulated wire using a 1/0.8 mm aluminum conductor (thin insulated wire with the sheath removed from the cable for Examples 2 and 10) produced in each example and comparative example was processed with a wire stripper, The presence or absence of whiskers was confirmed. The whiskers refer to linear bodies (hair-like bodies) of the insulating coating layer that remain on the cut end face (extend from the cut end face) because the insulating coating layer cannot be cut in the thickness direction.
A stripper with a hole diameter of 1.0 mm was used, and the stripping length of the sheath and covering layer was 15 mm. This processing was tested four times for each small-diameter insulated wire.
The evaluation was "A" when the length of the beard generated in the cut part was 3 mm or less in all four tests, and the length of the beard generated in the cut part in all four tests exceeded 3 mm and 6 mm. A case where the length of the whisker was below 6 mm was rated as "B", and a case where the length of the whisker generated at the cut portion even once exceeded 6 mm was rated as "C". In this test, evaluation ranks "A" and "B" are passed.

- 2. Remaining confirmation test of cut shavings -
The large-diameter insulated wires using the 38SQ aluminum stranded wire produced in each example and comparative example were processed with a wire stripper, and the cutting residue of the insulating coating layer remaining on the surface and inside of the aluminum stranded wire was confirmed.
A stripper with a hole diameter of 10 mm was used, and the peeling length of the coating layer was 15 mm. This processing was tested four times for each large-diameter insulated wire.
The evaluation was "A" when no cut residue remained in the aluminum stranded wire at the cut portion in all four tests, and when it was confirmed that cut residue remained in the aluminum stranded wire at the cut portion even once. was rated as "B", and a case in which cut shavings remained in the aluminum stranded wire at the cut portion in two or more tests was rated as "C". In this test, evaluation ranks "A" and "B" are passed.

- 3. Conductor damage (disconnection) confirmation test -
A large-diameter insulated wire using a 38SQ aluminum stranded wire manufactured in each example and comparative example was processed with a wire stripper, and the presence or absence of breakage of the aluminum stranded wire was confirmed.
A stripper with a hole diameter of 9.0 mm was used, and the stripping length of the coating layer was 15 mm. This processing was tested four times for each large-diameter insulated wire.
The evaluation was "A" when no breakage or damage (bend) of the aluminum strand was confirmed in all four tests, and "A" when breakage or damage (bend) of the aluminum strand was confirmed even once. "B", and "C" when cuts or scratches (bents) of the aluminum twisted wire were confirmed in two or more tests. In this test, the evaluation rank "A" is a pass.

<Flexibility test of insulated wire>
When the large-diameter insulated wire using the 38SQ aluminum stranded wire produced in each example and comparative example was bent into a U shape in 4D (D indicates the radius of the large-diameter insulated wire) (U-shaped bending The inner diameter of the part was four times the radius of the large diameter insulated wire), and the force required to bend it was measured with a Tensilon.
Tables 1-3 list the measured values of the force required to bend. In this test, when the force required for bending is 35N or less, it is "passed", and when it exceeds 35N, it is rejected.

<Heating winding test>
The heat resistance of the insulated wire was evaluated by the heating winding test described below.
Specifically, a thin insulated wire or cable using a 1/0.8 mm aluminum conductor manufactured in each example and comparative example was wound around a mandrel having the same outer diameter as the self diameter (diameter) for 6 turns. A test sample was made. This test sample was left in a constant temperature bath at 160° C. for 24 hours. After the standing, the test sample was returned to normal temperature, the thin insulated wire was unwound from the test sample, and its surface was confirmed. For the cables of Examples 2 and 10, the actual test was performed after removing the sheath (for the small-diameter insulated wire).
The evaluation was "A" when the thin insulated wire was not melted all over, and the thin insulated wire was melted and fused with the adjacent thin insulated wire (turn parts), but the aluminum conductor A case where the insulated wire was not visible was rated as "B", and a case where the thin insulated wire was melted and the aluminum conductor was exposed was rated as "C". In this test, the evaluation ranks "A" and "B" are passed, and these evaluation ranks are equal to or higher than the heat resistance exhibited by the thin insulated wire manufactured in the same manner except that the copper conductor was used. indicates

The results in Tables 1 to 3 reveal the following.
The wiring materials of the comparative examples, which did not use the aluminum conductor and the innermost coating layer composed of the silanol condensation cured product of the silane crosslinkable composition defined in the present invention, all exhibited excellent heat resistance, peelability and flexibility. It has been shown that it does not have both.
That is, Comparative Example 1 is a wiring material having an innermost coating layer made of a non-crosslinked resin composition containing a small amount of inorganic filler, and does not exhibit sufficient heat resistance. Comparative Example 2 is a wiring material having an innermost coating layer formed by self-crosslinking base resins with an organic peroxide instead of silane cross-linking, and is inferior in peelability and flexibility. Comparative Example 3 is a wiring material having an innermost coating layer formed using silane MB containing a small amount of inorganic filler, and is inferior in peelability and flexibility. Comparative Example 4 is a wiring material having an innermost coating layer formed using a base resin containing neither ethylene rubber nor styrene elastomer and silane MB containing no inorganic filler, and has sufficient peelability and flexibility. is not. Comparative Example 5 is a wiring material having an innermost coating layer formed using a silane MB in which the silane coupling agent is not grafted even though it contains ethylene rubber and a styrene elastomer. is not sufficient (the occurrence of whiskers cannot be suppressed during processing), and the heat resistance is also poor. Comparative Example 6 is a wiring material having an innermost coating layer formed using silane MB containing a large amount of inorganic filler, and has low flexibility and insufficient peeling processability (remaining cutting shavings during processing become conspicuous). Comparative Example 7 is a wiring material having an innermost coating layer formed using a silane crosslinkable composition that does not contain a silanol condensation catalyst, and the peelability is not sufficient (the generation of whiskers cannot be suppressed during processing). ) and poor heat resistance.
On the other hand, the wiring members of Examples 1 to 10, in which the aluminum conductor and the innermost coating layer composed of the silanol condensation cured product of the silane crosslinkable composition specified in the present invention are combined and arranged in direct contact, , all passed the insulated wire cutting property test, the insulated wire flexibility test, and the heating winding test, and it can be seen that they have high heat resistance and excellent peelability and flexibility.

Claims (5)

A wiring material having at least one insulating coating layer on the outer periphery of an aluminum conductor,
A wiring material in which the innermost insulating coating layer directly provided on the outer circumference of the aluminum conductor among the insulating coating layers is made of a silanol condensation cured product of the following silane crosslinkable composition.
<Silane crosslinkable composition>
100 parts by mass of a base resin containing at least one of ethylene rubber and styrene elastomer, 10 to 400 parts by mass of an inorganic filler, and 1 to 15.0 parts by mass of a silane coupling agent grafted to the base resin. and further containing a silanol condensation catalyst,
When the base resin contains a styrene-based elastomer, the content in the base resin is 10% by mass or more, and when the base resin contains an ethylene-vinyl acetate copolymer resin, A silane crosslinkable composition having a content of 20% by mass or less 2. The wiring material according to claim 1, wherein said base resin contains an organic mineral oil. The wiring material according to claim 1 or 2, wherein the total content of the ethylene rubber and the styrene-based elastomer in the base resin is 15% by mass or more . The wiring material according to any one of claims 1 to 3, wherein the inorganic filler contains at least one selected from the group consisting of metal hydrates, silica, calcium carbonate and clay. The wiring material according to any one of claims 1 to 4, wherein the insulating coating layer has two or more layers, and the outermost insulating coating layer is a polyvinyl chloride insulating coating layer.