JP2018014159A - Insulated wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulated wire which is excellent in flame retardancy and heat distortion resistance and can be produced at low cost.SOLUTION: An insulated wire has a conductor and an insulating layer which is laminated on a peripheral surface of the conductor and is formed by crosslinking a silane crosslinking resin composition, where the silane crosslinkable resin composition contains a non silane-crosslinkable polyolefin, a silane-crosslinkable polyolefin, a halogen flame retardant, a radical scavenger, a peroxide decomposer and a zinc oxide. The radical scavenger preferably contains a hindered phenolic antioxidant. The peroxide decomposer preferably contains a sulfur-based antioxidant. The sulfur-based antioxidant preferably contains 2-mercapto benzimidazole. The non silane-crosslinkable polyolefin is preferably a copolymer of ethylene and a polar monomer. A density of the silane-crosslinking polyolefin is preferably 0.95 g/cmor less.SELECTED DRAWING: None

Description

  The present invention relates to an insulated wire.

  An insulated wire generally includes a conductor made of copper, a copper alloy, or the like, and an insulating layer formed of a resin that covers the conductor. This insulated wire is not only required to have mechanical strength such as tensile properties, but also has high flame resistance and heat resistance (high heat aging) that can retain excellent mechanical properties even after exposure to high temperatures. Sex) is required. Various characteristics of these insulated wires are evaluated by, for example, UL (Underwriters Laboratories Inc.) standards.

  As a method for improving the flame retardancy of an insulated wire, there is a method of adding a flame retardant to an insulating layer. These flame retardants can be classified into halogen-based flame retardants such as brominated flame retardants and non-halogen-based flame retardants such as metal hydroxides. Is possible.

  On the other hand, there is a case where the insulated wire is required to have high heat distortion resistance so that it can withstand the solder reflow process, and as a method for improving the heat distortion resistance, there is a method of forming an insulation layer with crosslinked polyolefin. Examples of the method of crosslinking the polyolefin include crosslinking by electron beam irradiation, silane crosslinking using a silane crosslinkable polyolefin, and the like. Among these, when performing electron beam irradiation, it is necessary to install an expensive electron beam irradiation machine, but silane crosslinking is excellent in terms of cost because it does not require special equipment. In view of this, there has been proposed an insulated wire in which an insulating layer is formed from a resin composition obtained by combining this silane-crosslinkable polyolefin and a halogen-based flame retardant or a non-halogen-based flame retardant (Japanese Patent Laid-Open No. 9-92055 and Japanese Patent Laid-Open No. 2014-2014). No. 117172).

JP-A-9-92055 JP 2014-111721 A

  However, in the case of silane crosslinkable polyolefin, if the compounding agent has a catalytic effect of the silane crosslinking reaction, the crosslinking reaction proceeds during kneading or extrusion molding, resulting in deterioration of the extrusion appearance and a significant decrease in physical properties. There are restrictions on the compounding agents that can be used. For example, when adding a halogen-based flame retardant such as a brominated flame retardant to the resin composition forming the insulating layer in order to give the insulated wire high flame resistance that conforms to the UL standard horizontal combustion test, A small amount of thermal decomposition products generated from the halogen flame retardant during the extrusion process serve as a catalyst to promote the formation of a silane cross-linked structure. As a result, molding becomes difficult due to the occurrence of abnormal appearance, resulting in a decrease in yield. Physical properties may not be obtained.

  On the other hand, when a non-halogen flame retardant such as a metal hydroxide is added to the resin composition forming the insulating layer, it is necessary to add a larger amount than when using a halogen flame retardant. There is a risk that the antioxidant action is reduced due to the adsorption of the antioxidant due to, and the air enters the resin layer from the interface between the metal hydroxide and the resin. As a result, when a metal hydroxide and an antioxidant are used in combination, the heat resistance deformability obtained is limited to a heat resistance of 125 ° C. at the rated temperature of the UL standard, and it is difficult to achieve a heat resistance of 150 ° C. . Therefore, the conventional insulated wire described above satisfies the requirements of high flame retardancy and heat distortion resistance and is difficult to manufacture at low cost.

  This invention is made | formed based on the above situations, and it aims at provision of the insulated wire which is excellent in a flame retardance and heat-resistant deformation property, and can be manufactured at low cost.

  An insulated wire according to an aspect of the present invention made to solve the above-described problem includes a conductor and an insulating layer laminated on the conductor peripheral surface and formed by crosslinking of the silane crosslinkable resin composition. The silane crosslinkable resin composition contains a non-silane crosslinkable polyolefin, a silane crosslinkable polyolefin, a halogen flame retardant, a radical scavenger, a peroxide decomposer, and zinc oxide.

  The insulated wire according to one embodiment of the present invention is excellent in flame retardancy and heat distortion resistance and can be manufactured at low cost.

[Description of Embodiment of the Present Invention]
An insulated wire according to an aspect of the present invention is an insulated wire comprising a conductor and an insulating layer laminated on the conductor peripheral surface and formed by crosslinking of a silane crosslinkable resin composition, wherein the silane crosslinkable resin is provided. The composition contains a non-silane crosslinkable polyolefin, a silane crosslinkable polyolefin, a halogen flame retardant, a radical scavenger, a peroxide decomposer, and zinc oxide.

  The insulated wire forms an insulating layer by crosslinking of a silane crosslinkable resin composition containing a silane crosslinkable polyolefin and a halogen-based flame retardant. Therefore, this insulating layer has a high heat distortion property due to the polyolefin having a silane cross-linking structure, and also has a high flame resistance while maintaining the heat deformation property with a halogen-based flame retardant. Furthermore, since silane crosslinking can be performed by crosslinking by supplying moisture (water crosslinking) or the like, no special equipment is required. Therefore, the insulated wire is excellent in flame retardancy and heat distortion resistance and can be manufactured at low cost.

  Furthermore, since the insulated wire can suppress silane crosslinking by the halogen-based flame retardant during the kneading and extrusion molding described above, production at a low cost is promoted. The reason for this is not clear, but can be inferred as follows. That is, zinc oxide adsorbs the thermal decomposition product generated from the halogen-based flame retardant by heating during kneading and extrusion molding, thereby forming a silane crosslinked structure before extrusion due to the catalytic effect of this thermal decomposition product. It is thought to be suppressed. Moreover, it is thought that containing non-silane crosslinkable polyolefin as a resin component also suppresses the formation of a silane crosslinked structure during kneading and extrusion molding. Furthermore, the radical scavenger and the peroxide decomposer further improve the heat distortion resistance of the insulated wire.

  The radical scavenger may contain a hindered phenol antioxidant. The hindered phenol antioxidant is considered to improve the performance as a radical scavenger because the steric hindrance of the molecule contributes to the performance as a radical scavenger. Therefore, when the radical scavenger contains a hindered phenol antioxidant, the heat distortion resistance of the insulated wire can be further improved.

  The peroxide decomposer may contain a sulfur-based antioxidant. The sulfur-based antioxidant has an action as a peroxide decomposing agent, an action of suppressing auto-oxidation, and an action of capturing peroxide radicals by donating hydrogen. Moreover, a sulfur type antioxidant has the reproduction | regeneration effect | action of a hindered phenolic antioxidant by donating hydrogen to the hindered phenolic antioxidant used as the phenoxy radical. Therefore, when the peroxide decomposer contains a sulfur-based antioxidant, the heat distortion resistance of the insulated wire can be further improved.

  The sulfur-based antioxidant may include 2-mercaptobenzimidazole. 2-mercaptobenzimidazole is suitable for improving the heat distortion resistance at a relatively high temperature. Therefore, when a sulfur type antioxidant contains 2-mercaptobenzimidazole, the heat-resistant deformation property at the time of the comparatively high temperature of the said insulated wire can be improved more.

  The non-silane crosslinkable polyolefin is preferably a copolymer of ethylene and a polar monomer. Thus, non-silane crosslinkable polyolefin is the above-mentioned copolymer, thereby improving the dispersibility of each component such as a halogen-based flame retardant in the insulating layer of the insulated wire. Can be improved.

The density of the silane crosslinkable polyolefin is preferably 0.95 g / cm ³ or less. Thus, by making the density of the silane crosslinkable polyolefin smaller than the above upper limit, that is, having a relatively low density, the dispersibility of each component such as a halogen flame retardant in the insulating layer of the insulated wire is improved. As a result, flame retardancy and heat distortion resistance can be further improved.

  The polyolefin constituting the silane crosslinkable polyolefin may be polyethylene. Since polyethylene can graft a silane compound with high efficiency, the polyolefin constituting the silane crosslinkable polyolefin is made of polyethylene, so that the formation ratio of the silane crosslinked structure of the polyolefin in the insulating layer of the insulated wire is improved. Deformability can be further improved.

  The content of the halogen flame retardant with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin in the silane crosslinkable resin composition is preferably 1 part by mass or more and 30 parts by mass or less. Thus, by setting the content of the halogen-based flame retardant within the above range, the formation of silane crosslinking during kneading and extrusion molding can be further suppressed, and as a result, the flame resistance of the insulated wire is maintained. However, easier and more reliable manufacturing is possible.

  The insulated wire may pass the UL 1581 horizontal combustion test or the ISO 6722 standard 45 degree inclined flame retardant test. The tensile elongation after heating at 180 ° C. for 168 hours with respect to the tensile elongation at 25 ° C. of the insulating layer is preferably 80% or more. Furthermore, the tensile strength after heating for 168 hours at 180 ° C. with respect to the tensile strength at 25 ° C. of the insulating layer is preferably 80% or more. Thus, the said insulated wire which satisfy | fills the high flame retardance and heat-resistant deformation standard can be used suitably as an insulated wire of the environment where there exists a possibility of high temperature or a fire.

  Here, the “polyolefin density” is a value measured according to JIS-K7112: 1999 “Method for measuring density and specific gravity of plastic-non-foamed plastic”. “Tensile elongation” of an insulating layer is an insulation measured according to UL standard 758 7.2 (table 7.1) and 14 and UL standard 1581 table 50232 for an insulating layer from which a conductor is removed from an insulated wire. It is the elongation when the wire is cut. “Tensile strength” of an insulating layer is a value measured in accordance with UL standard 758 7.2 (table 7.1) and 14 and UL standard 1581 table 50.232 for an insulating layer obtained by removing a conductor from an insulated wire. It is.

[Details of the embodiment of the present invention]
Hereinafter, the said insulated wire which concerns on embodiment of this invention is explained in full detail.

<Insulated wire>
The insulated wire includes a conductor and an insulating layer laminated on the circumferential surface of the conductor. Although it does not specifically limit as a cross-sectional shape of the said insulated wire, For example, various shapes, such as a round shape, a square shape, a rectangle, are employable. Moreover, when making the cross-sectional shape of the said insulated wire into a circle, as a minimum of an average diameter, it can be 0.3 mm, for example. On the other hand, the upper limit of the average diameter can be set to 25 mm, for example. Moreover, when making the cross-sectional shape of the said insulated wire into a square, as a minimum of the average length of one side, it can be 0.3 mm, for example. On the other hand, the upper limit of the average length of the piece can be set to 25 mm, for example.

(conductor)
Although it does not specifically limit as a conductor, For example, metal wires, such as copper, copper alloy, aluminum, aluminum alloy, can be used.

  The cross-sectional shape of the metal wire forming the conductor is not particularly limited, and various shapes such as a circle, a rectangle, and a rectangle can be employed. Also, the size of the cross section of the metal wire is not particularly limited, but when the cross section of the conductor is circular, the lower limit of the average diameter can be set to, for example, 0.1 mm. On the other hand, the upper limit of the average diameter can be set to 5 mm, for example. Moreover, when the cross-sectional shape of the conductor is square, the lower limit of the average length of one side can be set to 0.5 mm, for example. On the other hand, the upper limit of the average length of the piece can be set to 5 mm, for example.

  The conductor can also be formed from a stranded wire obtained by twisting a plurality of metal wires. In this case, multiple types of metal wires may be combined. The number of twists is generally 7 or more.

(Insulating layer)
The insulating layer is formed by crosslinking of a silane crosslinkable resin composition described later, and is laminated on the peripheral surface of the conductor so as to cover the conductor. The insulating layer may be a single layer or a multilayer structure of two or more layers. The insulating layer may be a porous resin layer or a non-porous resin layer, but a non-porous resin layer is preferred from the viewpoint of mechanical strength. Here, the “non-porous resin layer” refers to a resin layer having a porosity of less than 20%. “Porosity” refers to the ratio of the area of the entire bubble to the cross-sectional area of the insulating layer in the cross section in any direction of the insulating layer. The upper limit of the porosity in the insulating layer is preferably 10%, more preferably 3%, and even more preferably 1%.

  Although it does not specifically limit as a minimum of the average thickness of an insulating layer, For example, it can be set to 0.1 mm. On the other hand, the upper limit of the average thickness of the insulating layer is not particularly limited, but can be, for example, 10 mm.

  The insulating layer may have a primer layer in contact with the conductor. As this primer layer, what hardened | cured crosslinkable resin, such as ethylene which does not contain a metal hydroxide, can be used conveniently. By providing such a primer layer, it is possible to prevent a decrease in peelability between the insulating layer and the conductor with time and prevent a reduction in efficiency of the wiring work.

(Silane crosslinkable resin composition)
The silane crosslinkable resin composition contains a non-silane crosslinkable polyolefin, a silane crosslinkable polyolefin, a halogen flame retardant, a radical scavenger, a peroxide decomposer, and zinc oxide. The silane crosslinkable resin composition may contain other components as long as the effects of the present invention are not impaired. However, as described above, since the non-porous resin layer is preferable as the insulating layer, it is preferable that the silane crosslinkable resin composition does not substantially contain a foaming agent.

(Non-silane crosslinkable polyolefin)
A non-silane crosslinkable polyolefin is a polyolefin which does not have crosslinkability by itself. Non-silane crosslinkable polyolefin may be used independently and may use 2 or more types together.

[Polyolefin]
Polyolefin is a resin containing olefins as monomers. Examples of the polyolefin include polyethylene (ethylene homopolymer), polypropylene (propylene homopolymer), polybutene-1 (1-butene homopolymer), ethylene-propylene copolymer, ethylene-1-butene copolymer, and ethylene. -4-methyl-1-pentene copolymer, ethylene-1-hexene copolymer, ethylene-1-octene copolymer, propylene-1-butene copolymer, propylene-ethylene-1-butene copolymer, Examples include propylene-4-methyl-1-pentene copolymer. The polyolefin may be a copolymer of an olefin and a polar monomer. As such a copolymer, for example, a copolymer of ethylene and a polar monomer such as ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene-ethyl acrylate copolymer, propylene- Examples thereof include a copolymer of propylene and a polar monomer such as a vinyl acetate copolymer.

  Among these, as the non-silane crosslinkable polyolefin, a copolymer of ethylene and a polar monomer is preferable, and an ethylene-vinyl acetate copolymer and an ethylene-ethyl acrylate copolymer are more preferable. Thus, by making the non-silane crosslinkable polyolefin a copolymer of ethylene and a polar monomer, the dispersibility of each component such as a halogen-based flame retardant in the insulating layer of the insulated wire is improved. The flammability and heat distortion resistance can be further improved. The lower limit of the content of the polar monomer in the copolymer can be appropriately changed according to the type of the polar monomer, and is, for example, 3% by mass. On the other hand, the upper limit of the content of the polar monomer in the copolymer can be appropriately changed according to the kind of the polar monomer, and is, for example, 45% by mass.

  When the non-silane crosslinkable polyolefin is an ethylene-vinyl acetate copolymer, the lower limit of the vinyl acetate monomer content is preferably 5% by mass, more preferably 15% by mass, and even more preferably 25% by mass. On the other hand, as an upper limit of content of a vinyl acetate monomer, 45 mass% is preferable, 35 mass% is more preferable, and 30 mass% is further more preferable. Furthermore, when the non-silane crosslinkable polyolefin is an ethylene-ethyl acrylate copolymer, the lower limit of the content of the ethyl acrylate monomer is preferably 3% by mass, more preferably 10% by mass, and even more preferably 15% by mass. On the other hand, as an upper limit of content of an ethyl acrylate monomer, 40 mass% is preferable, 30 mass% is more preferable, and 20 mass% is further more preferable. By making content of a vinyl acetate monomer and an ethyl acrylate monomer into the said range, the dispersibility of each components, such as a halogenated flame retardant, in the insulating layer of the said insulated wire can be improved more.

The lower limit of the density of the non-silane crosslinked polyolefin is not particularly limited, but is preferably 0.88 g / cm ^3, more preferably 0.90 g / cm ^3, more preferably 0.92 g / cm ^3. On the other hand, the upper limit of the density of the non-silane crosslinked polyolefin is not particularly limited, but is preferably 1.0 g / cm ^3, more preferably 0.98 g / cm ^3, more preferably 0.95 g / cm ^3. If the density of the non-silane crosslinkable polyolefin is smaller than the lower limit, the mechanical strength of the insulating layer of the insulated wire may be insufficient. On the contrary, when the density of non-silane crosslinkable polyolefin exceeds the said upper limit, there exists a possibility that the dispersibility of each component, such as a halogenated flame retardant, in the insulating layer of the said insulated wire may fall.

  The lower limit of the melt flow rate (hereinafter also referred to as “MFR”) when measured under the conditions of a load of 2.16 kgf of non-silane crosslinkable polyolefin and a temperature of 190 ° C. is preferably 0.1 g / 10 min, 0.7 g / 10 minutes is more preferable. On the other hand, the upper limit of the MFR of the non-silane crosslinkable polyolefin is preferably 20 g / 10 minutes, and more preferably 8 g / 10 minutes. When the MFR of the non-silane crosslinkable polyolefin is smaller than the above lower limit, the melt elongation of the silane crosslinkable resin composition becomes small and the extrusion moldability may be deteriorated. On the other hand, when the MFR of the non-silane crosslinkable polyolefin exceeds the above upper limit, the mechanical strength and the like of the insulating layer of the insulated wire may be lowered and a desired tensile strength may not be obtained.

  As a minimum of content of non-silane crosslinkable polyolefin in a silane crosslinkable resin composition, 10 mass% is preferred, 15 mass% is more preferred, and 20 mass% is still more preferred. On the other hand, the upper limit of the content is preferably 40% by mass, more preferably 30% by mass, and even more preferably 25% by mass. When the said content is smaller than the said minimum, melt viscosity becomes high in the case of kneading | mixing and extrusion molding, and there exists a possibility that extrusion moldability may deteriorate. Conversely, if the content exceeds the upper limit, the content of components such as silane crosslinkable polyolefin and halogen flame retardant may be insufficient.

[Silane crosslinkable polyolefin]
The silane crosslinkable polyolefin is obtained by grafting a silane compound to a polyolefin. Examples of the polyolefin to which the silane compound is grafted (hereinafter also referred to as “grafted polyolefin”) include those exemplified as the non-silane crosslinkable polyolefin, and among these, polyethylene is preferable. Since polyethylene can graft a silane compound with high efficiency, the formation ratio of the silane cross-linked structure of polyolefin in the insulating layer of the insulated wire can be improved, and the heat distortion resistance can be further improved. The polyolefin to be grafted may be used alone or in combination of two or more.

  A commercially available silane crosslinkable polyolefin may be used. Examples of commercially available silane crosslinkable polyolefins include “Linkron XLE815N”, “Linkron XCF710N”, and “Linkron SS732N” manufactured by Mitsubishi Chemical Corporation.

As a minimum of the density of silane crosslinkable polyolefin, 0.85 g / cm ³ is preferred, 0.88 g / cm ³ is more preferred, and 0.90 g / cm ³ is still more preferred. On the other hand, the upper limit of the density of the silane crosslinkable polyolefin, preferably 0.95 g / cm ^3, more preferably 0.93 g / cm ^3, more preferably 0.92 g / cm ^3. By setting the density of the silane crosslinkable polyolefin within the above range, the dispersibility of each component such as a halogen-based flame retardant in the insulating layer of the insulated wire can be improved, and the flame retardancy and heat distortion resistance can be further improved. If the density of the silane crosslinkable polyolefin is smaller than the lower limit, the mechanical strength of the insulating layer of the insulated wire may be insufficient. On the contrary, when the density of the silane crosslinkable polyolefin exceeds the above upper limit, the above-described dispersibility may not be improved.

  As a minimum of content of silane crosslinkable polyolefin in a silane crosslinkable resin composition, 30 mass% is preferred, 40 mass% is more preferred, and 45 mass% is still more preferred. On the other hand, as an upper limit of content of the silane crosslinkable polyolefin in a silane crosslinkable resin composition, 70 mass% is preferable, 60 mass% is more preferable, and 55 mass% is further more preferable. When the content of the silane crosslinkable polyolefin is smaller than the above lower limit, the heat distortion resistance and mechanical strength of the insulating layer of the insulated wire may be insufficient. On the other hand, when the content of the silane crosslinkable polyolefin exceeds the upper limit, the melt viscosity becomes high during kneading and extrusion molding, and the extrusion moldability may be deteriorated.

  The lower limit of the content of the silane crosslinkable polyolefin relative to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin in the silane crosslinkable resin composition is preferably 30 parts by mass, more preferably 50 parts by mass, 60 parts by mass is more preferable. On the other hand, the upper limit of the content of the silane crosslinkable polyolefin with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin in the silane crosslinkable resin composition is preferably 90 parts by mass, more preferably 80 parts by mass. Preferably, 70 mass parts is more preferable. When the content of the silane crosslinkable polyolefin is less than the above lower limit, the heat distortion resistance, mechanical strength, etc. of the insulating layer of the insulated wire may be insufficient. Conversely, when the content of the silane crosslinkable polyolefin exceeds the above upper limit, the content of the non-silane crosslinkable polyolefin may be insufficient.

  As a method for producing a silane crosslinkable polyolefin, for example, a polyolefin to be grafted, a silane compound and a radical generator are stirred at room temperature with a super mixer or the like and then grafted with a pressure kneader, a Banbury mixer, a twin screw or a single screw extruder. Examples thereof include a method of kneading while heating above the melting point of polyolefin. After the kneading is completed, when a pressure kneader or a Banbury mixer is used, the product extruded into a string shape (strand shape) with a feeder ruder is cooled with water, drained and then cut into pellets. When kneaded with a twin-screw or single-screw extruder, the mixture is originally extruded in a string shape (strand shape), so that it can be formed into a pellet by cutting it after water cooling and draining. The lower limit of the temperature at the time of kneading can be appropriately changed in consideration of the melting point of the polyolefin to be grafted, and can be, for example, 150 ° C. On the other hand, the upper limit of the temperature at the time of kneading can be appropriately changed in consideration of the melting point of the polyolefin to be grafted, and can be set to 200 ° C., for example.

As the silane compound, a compound represented by the general formula RR′SiY ₂ can be used. Here, R is a monovalent olefinically unsaturated hydrocarbon group, R ′ is a monovalent hydrocarbon group other than aliphatic unsaturated hydrocarbon or a hydrolyzable organic group, and Y is It is a hydrolyzable organic group. Among the compounds represented by the above formula, those in which R ′ and Y are the same hydrolyzable organic group, that is, the organic unsaturated silane represented by the general formula RSiY ₃ are preferable. Examples of the organic unsaturated silane include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, allyltrimethoxysilane, allyltriethoxysilane, oligomers of these organic unsaturated silanes, and the like. A silane compound may be used independently and may use 2 or more types together.

  As a minimum of content to 100 mass parts of polyolefin for grafting of a silane compound, 0.01 mass part is preferred and 0.1 mass part is more preferred. On the other hand, as an upper limit of content with respect to 100 mass parts of graft target polyolefin of a silane compound, 1.5 mass parts is preferable and 1.2 mass parts is more preferable. When the content of the silane compound is smaller than the above lower limit, grafting of the polyolefin to be grafted may be insufficient, and formation of the silane crosslinked structure of the polyolefin in the insulating layer formed by the silane crosslinkable resin composition may be insufficient. . On the contrary, when the content of the silane compound exceeds the above upper limit, it may be difficult to process the silane crosslinkable resin composition by kneading and extrusion molding, and the residual silane compound that is not grafted increases, and the insulation There is a risk of a decrease in adhesion between the insulating layer of the electric wire and the conductor.

  A radical generator may be used for grafting the silane compound. Examples of the radical generator include dicumyl peroxide, α, α′-bis (t-butylperoxydiisopropyl) benzene, di-t-butyl peroxide, t-butylcumyl peroxide, di-benzoyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, t-butylperoxypivalate, t-butylperoxy-2-ethylhexanoate and the like can be mentioned. A radical generating agent may be used independently and may use 2 or more types together.

  As a minimum of content with respect to 100 mass parts of graft object polyolefin of a radical generating agent, 0.02 mass part is preferred and 0.05 mass part is more preferred. On the other hand, the upper limit of the content of the radical generator with respect to 100 parts by mass of the polyolefin to be grafted is preferably 0.15 parts by mass, and more preferably 0.12 parts by mass. When the content of the radical generator is smaller than the above lower limit, grafting of the polyolefin to be grafted may be insufficient. On the contrary, when the content of the radical generator exceeds the above upper limit, the melt viscosity becomes high during the kneading and extrusion molding of the silane crosslinkable resin composition, and the extrusion moldability may be deteriorated. Grafting may occur and the appearance of the insulating layer of the insulated wire may be deteriorated.

[Halogen flame retardant]
The halogen-based flame retardant imparts flame retardancy to the insulating layer of the insulated wire. Examples of the halogen flame retardant include bromine flame retardant and chlorine flame retardant.

  Examples of brominated flame retardants include ethylene bistetrabromophthalimide, ethylene bis (pentabromophenyl), tetrabromoethane, tetraboromobisphenol A, hexabromobenzene, decabromobiphenyl ether, tetrabromophthalic anhydride, polydibromophenylene oxide. , Hexabromocyclodecane, ammonium bromide and the like.

  Examples of the chlorinated flame retardant include chlorinated paraffin, chlorinated polyethylene, chlorinated polyphenol, and perchlorpentacyclodecane.

  Of these, brominated flame retardants are preferred among the halogen-based flame retardants, and ethylene bistetrabromophthalimide (for example, “Cytex BT93” from Albemarle) and ethylene bis (pentabromophenyl) (for example, “Cytex from Albemarle). 8010 ") is more preferred. A halogen-type flame retardant may be used independently and may use 2 or more types together.

  As a minimum of content of a halogenated flame retardant in a silane crosslinkable resin composition, 1 mass part is preferred to 5 mass parts with respect to 100 mass parts of total contents of non-silane crosslinkable polyolefin and silane crosslinkable polyolefin. More preferred is 10 parts by mass, and especially preferred is 15 parts by mass. On the other hand, the upper limit of the content of the halogen-based flame retardant in the silane crosslinkable resin composition is preferably 30 parts by mass with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin, and 25 masses. Part is more preferable, and 20 parts by mass is even more preferable. When content of a halogenated flame retardant is smaller than the said minimum, there exists a possibility that the flame retardance of the insulating layer of the said insulated wire may become inadequate. On the other hand, when the content of the halogen flame retardant exceeds the above upper limit, there is a possibility that the adhesiveness between the insulating layer of the insulated wire and the conductor is deteriorated, the appearance is deteriorated.

  The silane crosslinkable resin composition may contain a non-halogen flame retardant such as a phosphorus flame retardant, a nitrogen flame retardant, magnesium hydroxide, and aluminum hydroxide in addition to the halogen flame retardant. The upper limit of the content of the non-halogen flame retardant in the silane crosslinkable resin composition is, for example, 10 parts by mass with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin.

[Radical scavenger and peroxide decomposer]
The radical scavenger (primary antioxidant) captures free radicals generated in the initial stage of oxidation, and the peroxide decomposer (secondary antioxidant) is peroxide (peroxide) generated by the reaction of free radicals. ) To be harmless. These two kinds of antioxidants improve the heat distortion resistance of the insulating layer of the insulated wire. Examples of the radical scavenger include hindered phenol antioxidants, hindered amine antioxidants, and the like. Examples of secondary antioxidants include sulfur-based antioxidants and phosphorus-based antioxidants.

  Examples of the hindered phenol antioxidant include pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,6-di-t-butyl-4-methylphenol. 2,5-di-t-butylhydroquinone, N, N′-hexamethylenebis (3,5-di-t-butyl-4-hydroxyhydrocinnamide, 3,5-di-t-butyl-4- Hydroxy-benzylphosphonate-diethyl ester, 2,4-bis [(octylthio) methyl] -o-cresol, 2,6-di-t-butyl-4-ethylphenol, 2,2′-methylenebis (4- Methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis 3-methyl-6-t-butylphenol), 2,5-di-t-amylhydroquinone, 2-t-butyl-6- (3-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate 4,4′-butylidenebis (3-methyl-6-tert-butylphenol) and the like.

  Examples of the hindered amine antioxidant include N- (2,2,6,6-tetramethyl-4-piperidyl) dodecylsuccinimide, N, N′-bis (2,2,6,6-tetramethyl). -4-piperidyl) butanetetracarboxylate, tetra (1,2,2,6,6-pentamethyl-4-piperidyl) butanetetracarboxylate, and the like.

  Among these, as the radical scavenger, a hindered phenol-based antioxidant is preferable, and pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (for example, “BASF” Irganox 1010 ") is more preferred. A radical scavenger may be used independently and may use 2 or more types together.

  The lower limit of the content of the radical scavenger in the silane crosslinkable resin composition is preferably 0.05 parts by mass with respect to 100 parts by mass of the total content of non-silane crosslinkable polyolefin and silane crosslinkable polyolefin, 0.3 Mass parts are more preferred, and 0.5 parts by mass are even more preferred. On the other hand, the upper limit of the content of the radical scavenger in the silane crosslinkable resin composition is preferably 10 parts by mass with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin, and 3 parts by mass. Is more preferable, and 1 part by mass is more preferable. When content of a radical scavenger is smaller than the said minimum, there exists a possibility that the heat-resistant deformation property of the insulating layer of the said insulated wire may become inadequate. On the other hand, when the content of the radical scavenger exceeds the above upper limit, there is a fear that the adhesiveness between the insulating layer of the insulated wire and the conductor is lowered.

  Examples of the sulfur-based antioxidant include phenothiazine, pentaerythritol-tetrakis (3-laurylthiopropionate), didodecyl sulfide, dioctadecyl sulfide, didodecylthiodipropionate, dioctadecylthiodipropionate, dimyristylthio. Examples include dipropionate, dodecyl octadecyl thiodipropionate, and 2-mercaptobenzimidazole.

  Examples of phosphorus antioxidants include triisodecyl phosphite, diphenylisodecyl phosphite, triphenyl phosphite, and trinonylphenyl phosphite.

  When the radical scavenger is a hindered phenol-based antioxidant, the peroxide decomposer is preferably a sulfur-based antioxidant, and more preferably 2-mercaptobenzimidazole (for example, “Sumilyzer MB” from Sumitomo Chemical Co., Ltd.). A peroxide decomposer may be used independently and may use 2 or more types together.

  The lower limit of the content of the peroxide decomposing agent in the silane crosslinkable resin composition is preferably 0.1 parts by mass with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin. Mass parts are more preferred, and 2.5 parts by mass are even more preferred. On the other hand, the upper limit of the content of the peroxide decomposing agent in the silane crosslinkable resin composition is preferably 20 parts by mass with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin. Mass parts are more preferred, and 4 parts by mass are even more preferred. When content of a peroxide decomposer is smaller than the said minimum, there exists a possibility that the heat-resistant deformation property of the insulating layer of the said insulated wire may become inadequate. On the other hand, when the content of the peroxide decomposing agent exceeds the above upper limit, there is a risk that the adhesiveness between the insulating layer and the conductor of the insulated wire will be lowered. Moreover, when the peroxide decomposing agent is a sulfur-based antioxidant, there is a risk of odor generation.

  The silane crosslinkable resin composition may contain other antioxidants. Examples of other antioxidants include metal deactivators that suppress the promotion of oxidation by heavy metals. Examples of the metal deactivator include hydrazine antioxidants and amide antioxidants. The upper limit of the content of other antioxidants in the silane crosslinkable resin composition is, for example, 3 parts by mass with respect to 100 parts by mass of the total content of non-silane crosslinkable polyolefin and silane crosslinkable polyolefin.

[Zinc oxide]
Zinc oxide suppresses the formation of a silane crosslinked structure before extrusion due to the catalytic effect of the pyrolysis product by adsorbing the pyrolysis product generated from the halogen-based flame retardant during kneading and extrusion molding. As a result, low-cost production of the insulated wire is promoted.

  The lower limit of the content of zinc oxide in the silane crosslinkable resin composition is preferably 0.1 parts by mass with respect to 100 parts by mass of the total content of non-silane crosslinkable polyolefin and silane crosslinkable polyolefin, 0.7 mass Part is more preferable, and 1.3 parts by mass is even more preferable. On the other hand, the upper limit of the content of zinc oxide in the silane crosslinkable resin composition is preferably 10 parts by mass and 5 parts by mass with respect to 100 parts by mass of the total content of non-silane crosslinkable polyolefin and silane crosslinkable polyolefin. More preferred is 2 parts by mass. When content of zinc oxide is smaller than the said minimum, there exists a possibility that the extrusion moldability of the said insulated wire may deteriorate. On the other hand, when the content of zinc oxide exceeds the above upper limit, there is a risk that the adhesiveness between the insulating layer and the conductor of the insulated wire will be lowered.

[Other ingredients]
Examples of other components include a silane crosslinking catalyst, a flame retardant aid, a lubricant, an antioxidant aid, a pigment, a reflection imparting agent, a masking agent, a processing stabilizer, and a plasticizer.

  The silane cross-linking catalyst promotes the formation of a silane cross-linked structure when an insulating layer is formed from the silane cross-linkable resin composition. The silane crosslinkable resin composition usually contains a silane crosslinking catalyst. As the silane crosslinking catalyst, an organometallic compound-based crosslinking catalyst can be used. Specifically, for example, dioctyltin dilaurate, dibutyltin dilaurate, stannous acetate, dibutyltin diacetate, dibutyltin dioctoate, zinc caprylate, tetrabutylester titanate, zinc stearate, calcium stearate and the like can be mentioned. . A silane crosslinking catalyst may be used independently and may use 2 or more types together.

  The lower limit of the content of the silane crosslinking catalyst in the silane crosslinkable resin composition is preferably 0.003 parts by mass with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin, Part by mass is more preferable. On the other hand, the upper limit of the content of the silane crosslinking catalyst in the silane crosslinkable resin composition is preferably 0.05 parts by mass with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin. 0.04 parts by mass is more preferable. When content of a silane crosslinking catalyst is smaller than the said minimum, there exists a possibility that crosslinking | crosslinking of silane crosslinkable polyolefin cannot fully be accelerated | stimulated. On the other hand, when the content of the silane crosslinking catalyst exceeds the above upper limit, local crosslinking occurs in the insulating layer of the insulated wire, and there is a possibility that the extrusion moldability deteriorates and the appearance deteriorates.

  A commercially available silane crosslinking catalyst may be used. Examples of commercially available silane crosslinking catalysts include “LZ033”, “LZ013”, “LZ015H”, etc., manufactured by Mitsubishi Chemical Corporation, and among these, “LZ033” is preferable. In addition, as a commercially available silane crosslinking catalyst, you may use what is provided as a pellet shape | molded with a resin component.

  When using the silane crosslinking catalyst provided as the pellet, the lower limit of the content of the pellet in the silane crosslinkable resin composition is appropriately set according to the content of the silane crosslinking catalyst in the pellet. The total content of non-silane crosslinkable polyolefin and silane crosslinkable polyolefin is 100 parts by mass, for example, 3 parts by mass. On the other hand, the upper limit of the content of the pellets in the silane crosslinkable resin composition is appropriately set according to the content of the silane crosslinking catalyst in the pellets, but non-silane crosslinkable polyolefin and silane crosslinkable polyolefin. The total content is, for example, 10 parts by mass with respect to 100 parts by mass.

  The flame retardant aid further improves the flame retardancy of the insulating layer of the insulated wire by a synergistic effect with the halogen-based flame retardant. Examples of the flame retardant aid include antimony compounds such as antimony trioxide, antimony tetroxide, and antimony pentoxide, tin compounds such as tin oxide and tin hydroxide, molybdate compounds such as molybdate oxide and ammonium molybdate, zirconium oxide, water Zirconium compounds such as zirconium oxide, boron compounds such as zinc borate and barium metaborate, silicon compounds such as high molecular weight silicon, silicon oil, silane coupling agents and the like. Of these, antimony compounds are preferred as flame retardant aids, and antimony trioxide is more preferred. A flame retardant adjuvant may be used independently and may use 2 or more types together.

  The lower limit of the content of the flame retardant aid in the silane crosslinkable resin composition is preferably 0.5 parts by mass with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin. Part is more preferable, and 7 parts by mass is even more preferable. On the other hand, the upper limit of the content of the flame retardant aid in the silane crosslinkable resin composition is preferably 30 parts by mass with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin, and 20 masses. Part is more preferable, and 10 parts by mass is even more preferable. When content of a flame retardant adjuvant is smaller than the said minimum, there exists a possibility that the flame retardance of the insulating layer of the said insulated wire may become inadequate. On the other hand, when the content of the flame retardant auxiliary exceeds the above upper limit, there is a risk that the adhesiveness between the insulating layer of the insulated wire and the conductor may be lowered.

  The lubricant improves fluidity when kneading and extruding the silane crosslinkable resin composition. Examples of the lubricant include hydrocarbons such as natural paraffin and low molecular weight polyethylene, fatty acids such as stearic acid, lauric acid and erucic acid, aliphatic alcohols such as cetyl alcohol and stearyl alcohol, stearic acid amide and melenbis stearoamide. Examples include lower alcohol esters of fatty acids such as fatty acid amides and butyl stearate, higher alcohol esters of higher fatty acids such as glycerin monostearate, and the like. As the lubricant, fatty acids are preferable, and stearic acid is more preferable. A lubricant may be used independently and may use 2 or more types together.

  The lower limit of the content of the lubricant in the silane crosslinkable resin composition is preferably 0.01 parts by mass, and 0.1 parts by mass with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin. Is more preferable, and 0.2 part by mass is even more preferable. On the other hand, the upper limit of the content of the lubricant in the silane crosslinkable resin composition is preferably 3 parts by mass and more preferably 1 part by mass with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin. 0.5 parts by mass is preferable. When the content of the lubricant is smaller than the above lower limit, the fluidity at the time of kneading and extrusion molding of the silane crosslinkable resin composition may be insufficient. On the contrary, when the content of the lubricant exceeds the above upper limit, the mechanical strength of the insulating layer of the insulated wire may be insufficient.

(Physical properties of insulating layer)
The lower limit of the tensile elongation at 25 ° C. of the insulating layer is preferably 300%, more preferably 350%. When tensile elongation is smaller than the said minimum, the flexibility of the said insulated wire may fall and it may be unsuitable for wiring.

  As a minimum of the tensile strength at 25 ° C of an insulating layer, 13.8MPa is preferred and 14.2MPa is more preferred. When the tensile strength is smaller than the above lower limit, the insulated wire may be broken in the wiring work.

  The lower limit of the tensile elongation (residual tensile elongation) after heating the insulating layer at 180 ° C. for 168 hours is preferably 80% and more preferably 85% with respect to the tensile elongation at 25 ° C. When the tensile elongation residual ratio is smaller than the lower limit, the flexibility of the insulating layer of the insulated wire may be reduced and broken under a high temperature environment.

  The lower limit of the tensile strength (residual tensile strength) after heating the insulating layer at 180 ° C. for 168 hours is 80%, preferably 95%, more preferably 100% with respect to the tensile strength at 25 ° C. When the tensile strength residual ratio is smaller than the lower limit, the insulating layer of the insulated wire may be broken under a high temperature environment.

(Physical properties of insulated wires)
It is preferable that the said insulated wire passes the 45 degree inclination flame-retardant test of ISO6722. As a procedure of this 45 degree inclination flame retardancy test, first, an insulated electric wire cut out to 600 mm is used as a sample, and this sample is fixed in a state inclined at an angle of 45 degrees with respect to a horizontal plane. Next, a flame of a gas burner is contacted at a position of 500 mm from the upper end of the sample, and the conductor is exposed, or for a predetermined time (if the average cross-sectional area of the conductor is 2.5 mm ² or less, the average of the conductor When the cross-sectional area exceeds 2.5 mm ² , the flame contact is terminated after 30 seconds). Then, the time from the end of flame contact until the sample self-extinguishes is measured, self-extinguishes within 70 seconds, and the case where the insulating layer remains 50 mm or more from the upper end of the sample passes, self-extinguishes within 70 seconds. The case where it did not exist, or the case where an insulating layer did not remain 50 mm or more from the upper end of a sample is made disqualified.

<Insulated wire manufacturing method>
Next, a method for manufacturing the insulated wire will be described. As a method for producing the insulated wire, for example, non-silane crosslinkable polyolefin, silane crosslinkable polyolefin, halogen flame retardant, radical scavenger, peroxide decomposer, zinc oxide and other components are melt-kneaded and silane crosslinkable. A step of preparing a resin composition (a silane crosslinkable resin composition preparation step), a step of extruding this silane crosslinkable resin composition on a conductor peripheral surface (extrusion step), and a crosslink of the extruded silane crosslinkable resin composition And a method including a step (crosslinking step) to be performed.

(Silane crosslinkable resin composition preparation step)
In this step, a silane crosslinkable resin composition is prepared. As a method for preparing a silane crosslinkable resin composition, for example, each component such as a non-silane crosslinkable polyolefin, a silane crosslinkable polyolefin, a halogen flame retardant, a radical scavenger, a peroxide decomposer, and zinc oxide as a material is used. Examples of the method include charging into a closed mixer such as a pressure kneader or a Banbury mixer, and setting the discharge temperature to about 160 ° C. and performing melt kneading. The lower limit of the discharge temperature at the time of kneading is preferably 140 ° C. from the viewpoint of preventing solidification in the mixer. The upper limit of the discharge temperature at the time of kneading is preferably 200 ° C. from the viewpoint of preventing burns due to heat. The melt-kneaded material is formed into a strip shape using an open roll and cut into a pellet shape using a pelletizer or the like, whereby a shape that can be charged into an extruder can be obtained.

(Extrusion process)
In this step, the silane crosslinkable resin composition obtained in the silane crosslinkable resin composition preparation step is extruded onto the conductor peripheral surface. In this step, the silane crosslinking catalyst pellets and the silane crosslinkable resin composition pellets are uniformly blended in advance using a Hensile mixer and then extruded to perform crosslinking in the crosslinking step described later in a short time. I can do it. As a minimum of extrusion temperature of this silane crosslinkable resin composition, it can be 130 ° C, for example. On the other hand, the upper limit of the extrusion temperature of the silane crosslinkable resin composition can be set to 210 ° C., for example. When extrusion temperature is smaller than the said minimum, extrusion torque does not fully fall, but a wire speed becomes low, and there exists a possibility that the productivity of the said insulated wire may deteriorate. On the other hand, when the extrusion temperature exceeds the above upper limit, the formation of the silane cross-linking structure proceeds in the extruder, and there is a possibility that the extrusion moldability of the insulated wire is deteriorated and the appearance is deteriorated.

  The lower limit of the linear drawing speed of the silane crosslinkable resin composition is preferably 5 m / min, and more preferably 10 m / min. On the other hand, the upper limit of the linear drawing speed of the silane crosslinkable resin composition is preferably 200 m / min. When extrusion line speed is smaller than the said minimum, there exists a possibility that the productivity of the said insulated wire may fall. On the other hand, when the extrusion wire speed exceeds the above upper limit, the load becomes excessive and there is a risk of damage such as cracking on the surface of the insulating layer of the insulated wire.

(Crosslinking process)
In this step, the extruded silane crosslinkable resin composition is crosslinked. Examples of this crosslinking method include water crosslinking, and specifically, silane-crosslinkable polyolefin is crosslinked by supplying moisture by exposure to air, immersion in water, exposure to water vapor atmosphere, and the like. Can be cured. By this curing, the insulating layer of the insulated wire is completed. The lower limit of the water crosslinking time can be, for example, 12 hours. On the other hand, the upper limit of the water crosslinking time can be set to 36 hours, for example. Moreover, as a minimum of the temperature of water bridge | crosslinking, it can be 10 degreeC, for example. Moreover, as an upper limit of the temperature of water bridge | crosslinking, it can be set as 80 degreeC, for example.

[Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The

  The insulated wire may further include a sheath layer on the outer peripheral surface side of the insulating layer. Examples of the material for forming the sheath layer include non-silane crosslinkable polyolefin, silane crosslinkable polyolefin, and combinations thereof. In addition, the material forming the sheath layer may contain a flame retardant, a flame retardant aid, an antioxidant and the like in order to improve the heat distortion resistance, flame retardancy, mechanical strength, etc. of the insulated wire.

  Hereinafter, although the insulated wire which concerns on 1 aspect of this invention is demonstrated further more concretely according to an Example, this invention is not limited to the following manufacture examples.

[Production Example 1]
(material)
100 parts by mass of an ethylene-vinyl acetate copolymer (“Evaflex EV270” from Mitsui-DuPont Polychemical Co., Ltd.) having an MFR of 1 g / 10 min and a vinyl acetate monomer content of 28% by mass as a non-silane crosslinkable polyolefin, silane 213 parts by mass of silane-crosslinkable polyethylene (Mitsubishi Chemical "Linklon XCF800N") as the crosslinkable polyolefin, bromine flame retardant (ethylene bistetrabromophthalimide: "Cytex BT93" from Albemarle) as the halogen flame retardant 50 parts by mass Part, hindered phenolic antioxidant (pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]: “IRGANOX 1010” from BASF) as a radical scavenger) Part, peroxide content 10 parts by mass of a sulfur-based antioxidant (2-mercaptobenzimidazole: “Sumilyzer MB” manufactured by Sumika Chemtex Co., Ltd.) as an agent, 5 parts by mass of zinc oxide, 20 parts by mass of a silane crosslinking catalyst (“LZ033” manufactured by Mitsubishi Chemical Corporation), 25 parts by mass of antimony trioxide as a flame retardant aid and 1 part by mass of stearic acid as a lubricant were prepared.

(Melt kneading and extrusion)
Components other than the silane crosslinking catalyst were melt-kneaded using a pressure kneader, discharged at a discharge temperature of 160 ° C., formed into a strip shape using an open roll, and cut into a pellet shape using a pelletizer. The pellets of the silane crosslinkable resin composition thus obtained and the silane crosslinking catalyst were uniformly blended using a Henschel mixer, and a single screw extruder (screw diameter: 60 mmφ, L / L) set at a cylinder temperature of 180 ° C. D = 24), and the outer peripheral surface of the conductor was extruded and covered. Extrusion was set so that the average outer diameter of the insulated wire was 1.5 mm, and the extrusion linear velocity was 100 m / min. As the conductor, a round annealed copper wire having an average diameter of 0.8 mm was used.

(Crosslinking)
The extruded silane crosslinkable resin composition was immersed in warm water at 60 ° C. for 24 hours for water crosslinking to obtain an insulated wire of Production Example 1.

[Production Example 2]
As non-silane crosslinkable polyolefin, 100 parts by mass of an ethylene-ethyl acrylate copolymer (“NUC6170” from NUC) having an MFR of 6 g / 10 min and an ethyl acrylate monomer content of 18% by mass is used. A silane crosslinkable resin composition was produced in the same manner as in Production Example 1, and an insulated wire of Production Example 2 was produced by extrusion molding and crosslinking under the same conditions as in Production Example 1.

[Production Example 3]
A silane crosslinkable resin composition is produced in the same manner as in Production Example 1 except that 200 parts by mass of a halogen-free flame retardant is used in the silane crosslinkable resin composition instead of the brominated flame retardant and flame retardant aid. Furthermore, the insulated wire of Production Example 3 was produced by extrusion molding and crosslinking under the same conditions as in Production Example 1.

[Production Example 4]
Using 300 parts by mass of a non-halogen flame retardant for the silane crosslinkable resin composition, the other materials and blends were prepared in the same manner as in Production Example 3 to prepare a silane crosslinkable resin composition, and extrusion under the same conditions as in Production Example 1 The insulated wire of Production Example 4 was produced by molding and crosslinking.

  Table 1 shows the composition of the materials used in Production Examples 1 to 4. In addition, each component of Table 1 shows together mass part and content (content with respect to all polyolefin) with respect to 100 mass parts of total content of non-silane crosslinkable polyolefin and silane crosslinkable polyolefin. In Table 1, “-” means that the corresponding component was not used, “EVA” represents an ethylene-vinyl acetate copolymer, and “EEA” represents an ethylene-ethyl acrylate copolymer.

<Evaluation>
About the insulated wire of the manufacture examples 1-4, the tensile elongation, the tensile strength, the tensile elongation residual rate, the tensile strength residual rate, the flame retardance (horizontal combustion test), and the heat deformation residual rate were evaluated with the following method. These evaluation results are shown in Table 2.

[Tensile elongation (unit:%)]
In accordance with UL standard 758 7.2 (table 7.1) and 14 and UL standard 1581 table 50.232, the test piece of the insulating layer from which the conductor was removed from the insulated wires of Production Examples 1 to 4 was measured by a tensile tester. The breaking length was measured by pulling at a pulling rate of / min, and the tensile elongation was calculated. Tensile elongation can be evaluated as good when the standard value is 300% or more, and poor when it is less than the standard value.

[Tensile strength (unit: MPa)]
In accordance with UL standard 758 7.2 (table 7.1) and 14 and UL standard 1581 table 50.232, the test piece of the insulating layer from which the conductor was removed from the insulated wires of Production Examples 1 to 4 was measured by a tensile tester. The maximum tensile load was measured by pulling at a pulling rate of / min, and the tensile strength was calculated. As for the tensile strength, the standard value is 13.79 MPa, and it can be evaluated as good when it is equal to or higher than the standard value and as defective when it is lower than the standard value.

[Remaining tensile elongation (unit:%)]
After the insulated wires of Production Examples 1 to 4 are heated at 180 ° C. for 168 hours, the conductor is removed from the insulated wires in accordance with UL standard 758, 7.2 (table 7.1) and 14 and UL standard 1581 table 50.232. The test piece of the insulating layer thus obtained was pulled at a tensile speed of 500 m / min with a tensile tester, the break length was measured, the tensile elongation was calculated, and the ratio to the tensile elongation before heating was determined. The tensile elongation residual rate can be evaluated as good when the standard value is 80% or more, and poor when it is less than the standard value.

[Remaining tensile strength ratio (unit:%)]
After heating the insulated wires of Production Examples 1 to 4 at 180 ° C. for 168 hours, in accordance with UL standard 758 7.2 (table 7.1) and 14 items and UL standard 1581 table 50.232, conductors and insulation from insulated wires The tensile strength was calculated by measuring the maximum tensile load by pulling the test piece of the insulating layer from which the layer had been removed at a tensile speed of 500 m / min with a tensile tester, and the ratio to the tensile strength before heating was determined. With respect to the tensile strength residual rate, the standard value is 80%, and it can be evaluated as good when it is equal to or higher than the standard value, and as poor when it is lower than the standard value.

[Flame retardance (horizontal combustion test of UL standard 1581)]
The insulated wires of Production Examples 1 to 4 were cut to a length of 254 mm, and a horizontal combustion test defined in UL standard 1581 was performed. In this horizontal combustion test, the flame of a tyryl burner was brought into contact with the lower side of the central part of the insulated wire held horizontally at an angle of 20 ° C. for 30 seconds, and the burning rate exceeded 25 mm / min. The case where the surgical cotton laid on the lower part burned was set as B (failure), and the case other than that was set as A (pass).

[Heat deformation residual ratio]
In accordance with UL standard 758, paragraph 19 (table 19.1) and UL standard 1581, 560, the insulated wires of Production Examples 1 to 4 are set in a 121 ° C. gear oven, preheated for 60 minutes, and then loaded from the top of the insulated wires The insulated wire is held for 1 hour with a disk-shaped jig having an outer diameter of 9.5 mm so as to be 2.45 N, and the residual deformation rate of the insulated wire [= 100 × (average thickness after heating / average thickness before heating)] The case of 50% or more was designated as A (pass), and the case of less than 50% was designated as B (failure).

  As shown from the results in Table 2, the insulated wires of Production Examples 1 and 2 satisfied the flame retardance standard, and had good mechanical strength and heat distortion resistance. On the other hand, although the insulated wire of Production Example 3 had good mechanical strength, it did not meet the flame retardancy standard and its heat distortion resistance was insufficient. Moreover, although the insulated wire of the manufacture example 4 satisfy | filled the flame retardance standard, mechanical strength and heat-resistant deformation were inadequate.

  As described above, the insulated wire according to one embodiment of the present invention is excellent in flame retardancy and heat distortion resistance and can be manufactured at low cost.

Claims (9)

Conductors,
An insulated wire comprising: an insulating layer laminated on the conductor peripheral surface and formed by crosslinking of a silane crosslinkable resin composition,
An insulated wire in which the silane crosslinkable resin composition contains a non-silane crosslinkable polyolefin, a silane crosslinkable polyolefin, a halogen flame retardant, a radical scavenger, a peroxide decomposer, and zinc oxide.   The insulated wire according to claim 1, wherein the radical scavenger contains a hindered phenol-based antioxidant.   The insulated wire according to claim 2, wherein the peroxide decomposer includes a sulfur-based antioxidant.   The insulated wire according to claim 3, wherein the sulfur-based antioxidant contains 2-mercaptobenzimidazole.   The insulated wire according to any one of claims 1 to 4, wherein the non-silane crosslinkable polyolefin is a copolymer of ethylene and a polar monomer. The density of the silane crosslinkable polyolefin insulated wire according to any one of claims 1 to 5 is 0.95 g / cm ³ or less.   The insulated wire according to any one of claims 1 to 6, wherein the polyolefin constituting the silane crosslinkable polyolefin is polyethylene.   The content of the halogen flame retardant with respect to 100 parts by mass of the total content of the non-silane crosslinkable polyolefin and the silane crosslinkable polyolefin in the silane crosslinkable resin composition is 1 part by mass or more and 30 parts by mass or less. Item 8. The insulated wire according to any one of items 7. Passed the standard 1581 horizontal combustion test or the ISO 6722 standard 45 degree inclined flame retardant test,
The tensile elongation after heating at 180 ° C. for 168 hours with respect to the tensile elongation at 25 ° C. of the insulating layer is 80% or more,
The insulated wire according to any one of claims 1 to 8, wherein a tensile strength of the insulating layer after heating at 180 ° C for 168 hours with respect to a tensile strength at 25 ° C is 80% or more.