JP2014047246A - Silane crosslinkable resin composition, insulation electric wire and production method of insulation electric wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation electric wire which maintains characteristics such as fire retardancy, and furthermore the production cost of which can be reduced in an accelerated manner, and to provided a production method of the insulation electric wire, and silane crosslinkable resin composition that is used for the production method.SOLUTION: There is provided the silane crosslinkable resin composition that contains: a base resin containing polyethylene and/or an ethylene-polar monomer copolymer as main components; and a nonhalogen flame retardant, where the nonhalogen flame retardant includes an aluminum hydroxide particle. A ratio of the aluminum hydroxide particle in the nonhalogen flame retardant is 50 mass% or more, mass percentage reduction of the aluminum hydroxide particle when the temperature thereof is raised from 110°C to 210°C is 0.15% or less, a content of the aluminum hydroxide particle based on 100 pts.mass of the base resin is 110 pts.mass or more and 250 pts.mass or less. The polyethylene is preferably a super low density polyethylene.

Description

  The present invention relates to a silane crosslinkable resin composition, an insulated wire, and a method for producing an insulated wire.

  Insulated wires constituting the wiring harness for electrical equipment are generally a conductor in which a plurality of metal wires made of copper, copper alloy, or the like are twisted, a resin insulating layer covering the conductor, and this It is comprised from the sheath layer laminated | stacked on the outer periphery of an insulating layer. As a resin used for the insulating layer and the sheath layer, a polyvinyl chloride resin has been conventionally used. However, there is a concern about contamination with a halogen element at the time of disposal. Recently, polyethylene and ethylene-polar monomer copolymers are used. A synthetic resin in which heat resistance is improved by cross-linking with a silane compound is used (see Japanese Patent Application Laid-Open No. 2007-207638).

  Insulated wires for the above applications require flame resistance in addition to weather resistance, mechanical strength, heat resistance, etc., so the synthetic resin that forms the sheath layer of this insulated wire includes aluminum hydroxide, magnesium hydroxide, etc. Metal hydroxide is added as a flame retardant. However, since aluminum hydroxide has a low decomposition temperature, water is generated in the synthetic resin due to the decomposition of aluminum hydroxide due to shear heat generation during extrusion molding, foaming occurs in the sheath layer, and quality such as poor appearance and reduced mechanical strength. There is a risk of lowering. Therefore, magnesium hydroxide having a high decomposition temperature is mainly used in conventional insulated wires. However, magnesium hydroxide has a high unit price and contributes to an increase in the manufacturing cost of insulated wires.

JP 2007-207638 A

  The present invention has been made based on the above circumstances, and is used for an insulated wire that can promote reduction in manufacturing cost while maintaining various properties such as flame retardancy, a manufacturing method thereof, and a manufacturing method thereof. An object is to provide a silane crosslinkable resin composition.

The invention made to solve the above problems is
A silane crosslinkable resin composition comprising a base resin mainly composed of polyethylene and / or ethylene-polar monomer copolymer and a non-halogen flame retardant, wherein the non-halogen flame retardant contains aluminum hydroxide particles,
The proportion of aluminum hydroxide particles in the non-halogen flame retardant is 50% by mass or more,
The mass reduction rate when the aluminum hydroxide particles are heated from 110 ° C. to 210 ° C. is 0.15% or less,
Content of the said aluminum hydroxide particle with respect to 100 mass parts of said base resins is 110 to 250 mass parts.

  Since the said silane crosslinkable resin composition contains the non-halogen flame retardant whose ratio of aluminum hydroxide particle | grains is 50 mass% or more, it is excellent in cost, having a flame retardance. In addition, the use of aluminum hydroxide particles with a minute amount of moisture generated by decomposition during extrusion molding can suppress foaming during extrusion molding, and have high flame resistance, mechanical strength, good appearance, etc. It can use suitably for manufacture of an electric wire.

  The polyethylene is preferably ultra-low density polyethylene. Thus, by using ultra-low density polyethylene as the main component of the base resin of the silane crosslinkable resin composition, the silane crosslinkable resin composition has high flexibility (flexibility) even at low temperatures. As a result, the wiring workability in a low-temperature environment of an insulated wire using the silane crosslinkable resin composition can be improved.

  It further contains a modified silicone compound containing a carbon-carbon double bond, the content of the modified silicone compound with respect to 100 parts by mass of the base resin is 0.1 parts by mass or more and 10 parts by mass or less, and the modified silicone compound is It is preferable that at least one terminal has at least one selected from the group consisting of a vinyl group, an acrylic group, and a methacryl group. Thus, the said silane crosslinkable resin composition can suppress the heat_generation | fever of shear at the time of extrusion molding of a sheath layer by containing the modified | denatured silicone compound containing a carbon-carbon double bond. As a result, the extrusion linear velocity can be improved, the productivity of the insulated wire using the silane crosslinkable resin composition can be improved, and the manufacturing cost can be further reduced. In particular, shear heat generation can be effectively suppressed by using a modified silicone compound having at least one of a vinyl group, an acrylic group, and a methacryl group at the terminal.

Moreover, another invention made in order to solve the said subject is:
An insulated wire comprising a conductor, an insulating layer covering the peripheral surface of the conductor, and a sheath layer covering the periphery of the insulating layer,
The sheath layer is formed from the silane crosslinkable resin composition.

  Since the insulated wire has a sheath layer formed using the silane crosslinkable resin composition, it has excellent flammability, and the amount of water generated from the aluminum hydroxide particles during extrusion is very small. In addition, it has excellent mechanical strength and can be manufactured at a low unit price.

Furthermore, another invention made to solve the above problems is
An insulated wire comprising a conductor, an insulating layer covering the peripheral surface of the conductor, and a sheath layer covering the periphery of the insulating layer,
The sheath layer is formed from a silane crosslinkable resin composition containing a base resin mainly composed of polyethylene and / or ethylene-polar monomer copolymer and a non-halogen flame retardant,
The non-halogen flame retardant contains aluminum hydroxide particles,
The proportion of aluminum hydroxide particles in the non-halogen flame retardant is 50% by mass or more,
Content of the said aluminum hydroxide particle with respect to 100 mass parts of said base resins is 110 mass parts or more and 250 mass parts or less,
Tensile strength is 8 MPa or more,
The tensile elongation is 125% or more.

  Since the insulated wire contains a non-halogen flame retardant in which the proportion of aluminum hydroxide particles is 50% by mass or more in the sheath layer, it has flame retardancy and is excellent in manufacturing cost. On the other hand, since it has the tensile strength and tensile elongation in the above range, it also has high mechanical strength.

Furthermore, another invention made to solve the above problems is
A method for producing an insulated wire comprising a conductor, an insulating layer covering the peripheral surface of the conductor, and a sheath layer covering the periphery of the insulating layer,
A method for producing an insulated wire, comprising: a step of laminating the silane crosslinkable resin composition on a peripheral surface of an insulating layer; and a step of crosslinking the silane crosslinkable resin composition.

  The insulated wire manufacturing method can easily and reliably manufacture an insulated wire having a sheath layer formed from the silane crosslinkable resin composition.

  Here, “mass reduction rate when aluminum hydroxide particles are heated from 110 ° C. to 210 ° C.” means that the mass measured after heating aluminum hydroxide particles to 110 ° C. and holding for 20 minutes is W1, the same water The mass measured after the aluminum oxide particles are heated to 210 ° C. and held for 10 minutes is defined as W2 and is a value obtained from (W1−W2) / W1 × 100.

  As described above, the silane crosslinkable resin composition of the present invention can be suitably used as a material for forming a sheath layer of an insulated wire. Moreover, the insulated wire of this invention can accelerate | stimulate reduction of manufacturing cost, maintaining various characteristics, such as a flame retardance.

  Hereinafter, embodiments of the silane crosslinkable resin composition of the present invention will be described in detail.

[Silane crosslinkable resin composition]
The said silane crosslinkable resin composition contains the base resin which has polyethylene and / or ethylene-polar monomer copolymer as a main component, the silane compound and radical generator which induce silane bridge | crosslinking, and a non-halogen flame retardant.

  Examples of the ethylene-polar monomer copolymer used in the base resin include ethylene vinyl acetate copolymer (EVA), ethylene acrylate copolymer (EEA), and random polypropylene copolymerized with ethylene. As the main component of the base resin used in the silane crosslinkable resin composition, very low density polyethylene (VLDPE) having high flexibility at low temperature is particularly preferable among the above-described polymers. The base resin may contain a plurality of types of resins, and may contain a small amount of a resin other than polyethylene and ethylene-polar monomer copolymer as a resin other than the main component.

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 hydrolyzed. It is a degradable organic group. Among the compounds represented by the above formula, preferred is an organic unsaturated silane represented by the general formula RSiY ₃ where R ′ is the same hydrolyzable organic group as Y. Examples of the organic unsaturated silane include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, allyltrimethoxysilane, allyltriethoxysilane, and oligomers thereof.

  As a minimum of content with respect to 100 mass parts of base resins 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 base resins 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 less than the lower limit, graft polymerization of the base resin becomes insufficient, and the crosslinking may not proceed sufficiently. On the contrary, when the content of the silane compound exceeds the above upper limit, the workability of the silane crosslinkable resin composition may be lowered, and the residual silane that is not graft-polymerized increases, and when the sheath layer of the insulated wire is formed. There is a possibility that the adhesion with the insulating layer may be reduced.

  Examples of the radical generator include dicumyl peroxide, α, α′-bis (t-butylperoxydiisopropyl) benzene, di-t-butyl peroxide, t-butylcumyl peroxide, di-benzoyl peroxide, Examples include 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, t-butylperoxypivalate, t-butylperoxy-2-ethylhexanoate, and the like.

  As a minimum of content with respect to 100 mass parts of base resins of a radical generating agent, 0.02 mass part is preferable and 0.05 mass part is more preferable. On the other hand, the upper limit of the content of the radical generator with respect to 100 parts by mass of the base resin is preferably 0.15 parts by mass, and more preferably 0.12 parts by mass. When the content of the radical generator is less than the above lower limit, the graft polymerization of the base resin may be insufficient. On the other hand, when the content of the radical generator exceeds the above upper limit, the processability of the silane crosslinkable resin composition may be lowered, and local graft polymerization may occur, which may deteriorate the molded appearance. is there.

  It is preferable to add a silane crosslinking catalyst to the silane crosslinkable resin composition in order to promote graft polymerization of the silane compound. As the silane crosslinking catalyst, an organometallic compound-based crosslinking catalyst can be used. Specific examples include dioctyltin, dibutyltin dilaurate, stannous acetate, dibutyltin diacetate, dibutyltin dioctoate, zinc caprylate, tetrabutyl ester titanate, zinc stearate, calcium stearate and the like.

  As a minimum of content with respect to 100 mass parts of base resins of a silane crosslinking catalyst, 0.01 mass parts is preferred and 0.03 mass parts is more preferred. On the other hand, as an upper limit of content with respect to 100 mass parts of base resins of a silane crosslinking catalyst, 0.15 mass parts is preferable and 0.12 mass parts is more preferable. When the content of the silane crosslinking catalyst is less than the above lower limit, the graft polymerization of the base resin may not be sufficiently promoted. On the other hand, when the content of the silane crosslinking catalyst exceeds the above upper limit, local crosslinking may occur and the molded appearance may be deteriorated.

  As the non-halogen flame retardant, for example, metal hydroxides such as magnesium hydroxide and aluminum hydroxide can be used. In the present invention, the proportion of aluminum hydroxide particles in the whole non-halogen flame retardant is 50% by mass or more. It is an essential requirement. The proportion of aluminum hydroxide particles in the non-halogen flame retardant is more preferably 80% by mass or more, and particularly preferably 100% by mass. By making the proportion of the aluminum hydroxide particles in the halogen flame retardant in this way, the cost can be reduced while maintaining the flame retardancy of the silane crosslinkable resin composition.

  The aluminum hydroxide particles added to the silane crosslinkable resin composition have a mass reduction rate of 0.15% or less when the temperature is raised from 110 ° C. to 210 ° C. The mass reduction rate is more preferably 0.11% or less. This mass reduction rate represents the mass proportion of water that is decomposed and released from the aluminum hydroxide particles during heating. Therefore, when the mass reduction rate exceeds the above range, the amount of water released from the aluminum hydroxide particles during extrusion molding of the sheath layer of the insulated wire increases, foaming occurs in the sheath layer, and the appearance, mechanical strength, etc. deteriorate. There is a risk.

Aluminum hydroxide particles having a mass reduction rate in the above range can be produced, for example, by the method described in JP-A-2002-348408. Specifically, for example, aluminum hydroxide having an average particle diameter of 2 μm, Na ₂ O content of 0.19 mass%, and SiO ₂ content of 0.01 mass% is dissolved in water so that the solid content concentration becomes 110 g / L. In this slurry, a sodium aluminate solution having a Na ₂ O / Al ₂ O 3 molar ratio of 1.5 and a SiO ₂ content of 0.06 g / L is used, and the volume ratio of the aluminum hydroxide slurry and the sodium aluminate solution is 1 .5: Supply while maintaining the liquid temperature at 80 ° C. to be 170. Thereafter, the slurry is kept at 70 ° C. for 4 hours to crystallize aluminum hydroxide, and the solid content is dried at 120 ° C. for 3 hours and then heat-treated at 200 ° C. for 24 hours. The aluminum hydroxide particles used in the above can be obtained.

  The minimum of content with respect to 100 mass parts of base hydroxide of the aluminum hydroxide particle in the said silane crosslinkable resin composition is 110 mass parts, and 150 mass parts is more preferable. On the other hand, the upper limit of the content of aluminum hydroxide particles with respect to 100 parts by mass of the base resin is 250 parts by mass, and more preferably 200 parts by mass. When the content of aluminum hydroxide particles is less than the above lower limit, the flame retardancy of the silane crosslinkable resin composition may not be sufficiently improved. On the contrary, when the content of aluminum hydroxide particles exceeds the above upper limit, the viscosity of the silane crosslinkable resin composition increases, so that the surface is not smoothly formed during the extrusion molding of the sheath layer of the insulated wire, resulting in unevenness. There is a possibility that the extrusion wire speed is lowered and the productivity of the insulated wire is deteriorated.

  The silane crosslinkable resin composition preferably contains a modified silicone compound containing a carbon-carbon double bond in order to suppress shearing heat generation during extrusion molding.

  As the modified silicone compound containing this carbon-carbon double bond, it is preferable to use a compound represented by the following formula (1) or (2).

（式（１）中、Ｒ^１は非反応性のアルキル基、Ｒ^２は炭素−炭素二重結合を含む基である。ｎは１以上の整数である。）

(In formula (1), R ¹ is a non-reactive alkyl group, R ² is a group containing a carbon-carbon double bond, and n is an integer of 1 or more.)

（式（２）中、Ｒ^１、Ｒ^２及びｎは上記式（２）と同義である。ｍは１以上の整数である。）

(In the formula (2), R ¹ , R ² and n are as defined in the above formula (2). M is an integer of 1 or more.)

Examples of the non-reactive alkyl group represented by R ¹ include a methyl group and a butyl group. Examples of the group containing a carbon-carbon double bond represented by R ² include a group containing a vinyl group, a group containing an acrylic group, and a group containing a methacryl group.

  The modified silicone compound containing a carbon-carbon double bond is preferably a compound represented by the formula (1), and at least one selected from the group consisting of a vinyl group, an acrylic group and a methacryl group at at least one end. What has a seed | species is more preferable, and the thing whose terminal is a vinyl group is especially preferable.

  In addition, as a group containing an acrylic group and a methacryl group used in the above formula (1) or (2), for example, those represented by the following formula (3) can be used.

  The lower limit of the content of the modified silicone compound containing the carbon-carbon double bond in the silane crosslinkable resin composition with respect to 100 parts by mass of the base resin is preferably 0.1 parts by mass, and more preferably 1 part by mass. On the other hand, the upper limit of the content of the modified silicone compound containing a carbon-carbon double bond with respect to 100 parts by mass of the base resin is preferably 10 parts by mass, and more preferably 9 parts by mass. When the content of the modified silicone compound is less than the above lower limit, the effect of suppressing shearing heat generation may not be sufficiently exhibited. On the other hand, when the content of the modified silicone compound exceeds the upper limit, the mechanical strength of the sheath layer of the insulated wire formed with the silane crosslinkable resin composition may decrease.

  In addition to the above additives, the silane crosslinkable resin composition includes melamine flame retardants, ammonium polyphosphate flame retardants, red phosphorus, silicone flame retardants, zinc stannate, zinc borate, zinc carbonate and the like. A flame retardant may be added. Moreover, you may add suitably additives, such as an inorganic filler, a coloring agent, a ultraviolet absorber, antioxidant, and a lubrication agent, to the said silane crosslinkable resin composition.

  Next, an embodiment of the insulated wire of the present invention will be described in detail.

[Insulated wire]
The insulated wire includes a linear conductor, an insulating layer covering the peripheral surface of the conductor, and a sheath layer covering the periphery of the insulating layer.

<Conductor>
The conductor used for the insulated wire is not particularly limited, and for example, a metal wire such as copper, copper alloy, aluminum, and 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 adopted. Further, the size of the cross section of the metal wire is not particularly limited. In the case of a round wire, one having a diameter of 100 μm to 5 mm is generally used, and in the case of a flat wire, one having a side length of 500 μm to 5 mm is generally used.

  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 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 material of the insulating layer is not particularly limited as long as it has insulating properties, and for example, the silane crosslinkable resin composition can be used. However, when using for an insulating layer, the silane crosslinkable resin composition does not need to contain a non-halogen flame retardant. The insulating layer can be obtained by extruding the silane crosslinkable resin composition onto the conductor peripheral surface and crosslinking in an atmosphere with moisture.

  Although it does not specifically limit as average thickness of an insulating layer, For example, it is 0.1 mm or more and 10 mm or less.

  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.

<Sheath layer>
The sheath layer is laminated on the peripheral surface of the insulating layer so as to cover the insulating layer. The sheath layer may be a single layer or a multilayer structure of two or more layers.

  The sheath layer can be obtained by extruding the silane crosslinkable resin composition described above on the peripheral surface of the insulating layer and crosslinking in a moisture atmosphere.

  Although it does not specifically limit as average thickness of a sheath layer, For example, they are 0.1 mm or more and 10 mm or less.

<Insulated wire>
The lower limit of the tensile strength of the insulated wire is preferably 8 MPa, and more preferably 8.5 MPa. On the other hand, the upper limit of the tensile strength is preferably 15 MPa. When the tensile strength is less than the above lower limit, the insulated wire may be broken in the wiring work. On the other hand, when the tensile strength exceeds the above upper limit, there is a risk of increasing the cost when stably manufacturing the insulated wire. The tensile strength is a value measured according to the “rubber / plastic insulated wire test method” described in JIS-C3005.

  The lower limit of the tensile elongation of the insulated wire is preferably 125%, more preferably 150%. On the other hand, the upper limit of tensile elongation is preferably 300%. When tensile elongation is less than the said minimum, the flexibility of the said insulated wire may fall and it may be unsuitable for wiring. On the other hand, when the tensile strength exceeds the above upper limit, there is a risk of increasing the cost when stably manufacturing the insulated wire. The tensile elongation is the elongation at the time of cutting an insulated wire measured in accordance with the “rubber / plastic insulated wire test method” described in JIS-C3005.

<Insulated wire manufacturing method>
The said insulated wire can be manufactured with the manufacturing method which has the following processes, for example.
(1) Conductor manufacturing process for manufacturing a conductor (2) Insulating layer coating process for laminating an insulating layer on the conductor peripheral surface (3) Batch manufacturing process for manufacturing various batches containing the composition of the sheath layer (4) A sheath layer coating process that mixes, extrudes and crosslinks to the peripheral surface of the insulating layer

<(1) Conductor manufacturing process>
In the conductor manufacturing process, first, copper or the like, which is a raw material for the conductor, is cast and rolled to obtain a rolled material. Next, this rolled material is subjected to wire drawing to form a wire drawing material having an arbitrary cross-sectional shape and wire diameter (short side width). As a method of wire drawing, for example, by using a wire drawing device equipped with a plurality of wire drawing dies, a rolled material coated with a lubricant is inserted into the wire drawing dies, thereby obtaining a desired cross-sectional shape and wire diameter (short side width). ) Can be used. Note that the cross-sectional processing can also be performed separately after softening described later.

  After the wire drawing, the wire drawing material is softened by heating to obtain a conductor metal wire. Since the crystal of the wire drawing material is recrystallized by performing the softening treatment, the toughness of the conductor can be improved. This softening treatment can be performed in an air atmosphere, but is preferably performed in a non-oxidizing atmosphere with a low oxygen content.

  When a stranded wire composed of a plurality of metal wires is used as a conductor, a conductor can be obtained by twisting a plurality of the metal wires.

<(2) Insulating layer coating process>
In the insulating layer coating process, a mixture of insulating layer forming materials mixed at a predetermined ratio is put into a melt extruder, then extruded and laminated on the peripheral surface of the conductor, and further crosslinked to form an insulating layer. Form. The specific procedure of this extrusion molding can be the same as the sheath layer coating step described later.

<(3) Batch manufacturing process>
In the batch manufacturing process, a batch in which various additives are mixed with the base resin is manufactured. Specifically, for example,
(A) A silane compound batch in which a radical generator, a silane compound, etc. are blended with a base resin,
Three types of batches are produced: (B) a flame retardant batch in which aluminum hydroxide particles are blended with the base resin, and (C) a catalyst batch in which a silane crosslinking catalyst is blended with the base resin. In the silane compound batch, the silane compound may be previously graft polymerized to the base resin.

  Moreover, you may manufacture two types of batches, the flame retardant mixing | blending silane compound batch which mix | blended the aluminum hydroxide particle mix | blended with the said silane compound batch, and the said catalyst batch. In this case, in order to suppress the interaction between the aluminum hydroxide particles and the silane compound and reliably perform the graft polymerization, it is preferable to mix the aluminum hydroxide particles with the base resin in which the silane compound is previously graft polymerized.

  The silane compound batch is manufactured by, for example, supplying the base resin with a mixture of the silane compound and the radical generator while heating and stirring the base resin, and impregnating the base resin with the silane compound and the radical generator. Can do. The temperature at the time of stirring can be appropriately determined in consideration of the melting point of the resin and the 10-hour half-life temperature of the radical generator, but about 80 ° C. is preferable. Moreover, as a device for heating and stirring the base resin, for example, a super mixer or the like can be used.

  In the above silane compound batch, when the silane compound is preliminarily graft-polymerized to the base resin, for example, the composition in which the base resin is impregnated with the silane compound and the radical generator is extruded and granulated by heating with an extrusion mixer. Can produce batches. As heating temperature at this time, 150 degreeC or more and 190 degrees C or less are preferable, for example.

  The flame retardant batch, the catalyst batch, and the flame retardant blended silane compound batch can be produced, for example, by melt-kneading the blend into the base resin using a known mixing device. Examples of the mixing device include an open roll mixer, a pressure kneader, and a banbury.

<(4) Sheath layer coating step>
In the sheath layer coating step, the batch mixed at a predetermined ratio is put into a melt extruder, then extruded and laminated on the peripheral surface of the insulating layer, and further crosslinked to form a sheath layer. .

  As extrusion temperature of a sheath layer composition, it can be set as 120 to 200 degreeC, for example. When a silane compound batch in which no silane compound is graft-polymerized is used for the base resin, the temperature is preferably 160 ° C. or higher and 190 ° C. or lower. By setting it as such a temperature range, the graft polymerization of the silane compound to the base resin can be promoted.

  The lower limit of the linear drawing speed of the sheath layer composition is preferably 55 m / min, and more preferably 65 m / min. On the other hand, the upper limit of the extrusion linear velocity is preferably 300 m / min. When extrusion line speed is less than the said minimum, there exists a possibility that productivity of the said insulated wire may fall. On the other hand, when the extrusion linear velocity exceeds the above upper limit, the load becomes excessive and damage such as cracks may occur on the surface of the sheath layer.

  The sheath layer composition laminated on the peripheral surface of the insulating layer by the above-mentioned extrusion molding causes the base resin to be silane-crosslinked by supplying moisture by exposure to the atmosphere, immersion in water, exposure to a water vapor atmosphere, etc. It can be cured. This curing completes the sheath layer.

  Since the insulated wire has excellent properties such as flame retardancy, it can be suitably used for outdoor wiring. Furthermore, since the insulated wire has a low manufacturing cost, it can be suitably used as a cable for transmitting, for example, the power generated by the solar cell module to the outside. As such a power transmission cable, the insulated wire can be used alone or as a wire harness in which a plurality of insulated wires are combined.

  Hereinafter, although the insulated wire of this invention is demonstrated more concretely according to an Example, this invention is not limited to a following example.

  In addition, each measured value in a present Example is a value measured with the following method.

[Tensile strength (unit: MPa)]
In accordance with “Rubber / Plastic Insulated Wire Test Method” described in JIS-C3005 (2000), the test piece of the sheath layer from which the conductor and the insulating layer were removed from the insulated wire was pulled at a tensile speed of 200 m / min. The maximum tensile load was measured and the tensile strength was calculated.

[Tensile elongation (unit:%)]
In accordance with “Rubber / Plastic Insulated Wire Test Method” described in JIS-C3005 (2000), the test piece of the sheath layer from which the conductor and the insulating layer were removed from the insulated wire was pulled at a tensile speed of 200 m / min. Then, the breaking length was measured, and the tensile elongation was calculated.

[Maximum linear drawing speed (m / min)]
In the extrusion molding of the sheath layer, extrusion was performed at the maximum extrusion linear velocity at which a sheath layer having a smooth appearance without defects such as irregularities on the surface could be extruded.

  In this example, the following quality evaluation was performed.

[Flame retardance (vertical single-flammability)]
In accordance with EN60332-1-2 (IEC 603322-1 / JIS-C3665-1), the insulated wire is held vertically, the burner is placed at an angle of 45 degrees with respect to the insulated wire, and the flame of the burner is exposed to the surface of the insulated wire. The carbonization state of the insulated wire after a specified test time was observed. The case where the distance between the lower end of the insulated wire and the carbonization start point was 50 mm or more was evaluated as ◯ (pass), and the case where the distance was less than 50 mm was determined as x (failed).

[Low temperature flexibility]
In accordance with EN60881-1-4, after being held for 16 hours in an environment of −40 ± 2 ° C., the cracks after being wound around the mandrel with the specified diameter at a rotation speed of 1/5 turns at the specified number of times. The presence or absence was examined. The case where there was no crack on the surface of the insulated wire was indicated as ◯ (passed), and the case where there was a crack was indicated as x (failed).

[Example 1]
(Manufacture of silane compound batches)
While stirring the base resin under the conditions of 80 ° C. and 60 rpm using a supermixer, the mixed liquid in which the silane compound and the radical generator were mixed was put into the supermixer and impregnated into the base resin. Next, the base resin impregnated with the silane compound and the radical generator was extruded at 150 to 190 ° C. using an extruder to granulate a silane compound batch.

  In the silane compound batch, the content of the silane compound with respect to 100 parts by mass of the base resin was 1 part by mass, and the content of the radical generator was 0.1 parts by mass.

(Production of flame retardant batch)
The base resin and aluminum hydroxide particles were charged into a pressure kneader and melt-kneaded for 10 minutes at a starting temperature of 140 ° C. and a kneading temperature of 160 ° C. Next, this kneaded resin was extruded with an extruder to granulate a flame retardant batch. When the aluminum hydroxide particles are heated from 110 ° C. to 210 ° C., the mass reduction rate is 0.1%.

(Manufacture of catalyst batch)
Under the same conditions as the above-mentioned flame retardant batch, the base resin, the silane crosslinking catalyst, the antioxidant and the lubricant were charged into a pressure kneader and melt kneaded, and the catalyst batch was granulated with an extruder.

  In addition, only the very low density polyethylene (VLDPE) was used for the said base resin. Further, vinylsilane (trade name: KBM-1003 Shin-Etsu Chemical Co., Ltd.) is used as the silane compound, dicumyl peroxide (trade name: Parkmill D NOF Corporation) is used as the radical generator, and dioctyltin ( Product name: Neostan U-810 Nitto Kasei Co., Ltd.), hindered phenol (product name: Irganox 1010 BASF) as the antioxidant, and paraffin wax (product name: High Wax 420P Mitsui Chemicals) as the lubricant. Using.

(Manufacture of insulated wires)
The silane compound batch, the flame retardant batch, and the catalyst batch were charged into a melt extruder (caliber: 50 mm, effective screw length: 24), and the sheath layer was extruded on the peripheral surface of the insulating layer at 150 to 190 ° C. At this time, the input amount of each batch is 120 parts by mass of aluminum hydroxide particles, 0.1 part by mass of the silane crosslinking catalyst, 2 parts by mass of the antioxidant, and 1 part by mass of the lubricant with respect to 100 parts by mass of the base resin. It adjusted so that it might become a part. Moreover, the extrusion linear velocity is 100 m / min. This extrusion drawing speed is the maximum drawing speed at which a sheath layer having a smooth appearance with no defects such as irregularities on the surface can be formed by extrusion using the resin composition having the above blending ratio.

The extruded sheath layer was immersed in warm water at 60 ° C. for 12 hours, cured by silane crosslinking, and the insulated wire of Example 1 was obtained. As the conductor, a conductor having a nominal cross-sectional area of 5.0 cm ^{2 obtained by} twisting 65 copper wires having a diameter of 0.32 mm was used. Moreover, the insulating layer was extrusion-molded on the same conditions as a sheath layer using the composition containing the base resin similar to a sheath layer, a silane compound, a radical generator, and a silane crosslinking catalyst.

[Examples 2 and 3]
Using the same material as in Example 1, the insulated wires of Examples 2 and 3 were manufactured. However, the input amount of each batch was adjusted so that the content of aluminum hydroxide particles was 160 parts by mass in Example 2 and 240 parts by mass in Example 3 with respect to 100 parts by mass of the base resin. The content of other compounding agents was the same as in Example 1.

[Example 4]
An insulated wire of Example 4 was produced using the same composition and content ratio as Example 2 except that ethylene vinyl acetate copolymer (EVA) was used instead of VLDPE as the base resin.

[Examples 5, 6 and 7]
The content of the modified silicone compound having a vinyl group at the terminal of the catalyst batch is 0.2 parts by mass in Example 5, 8 parts by mass in Example 6, and 10 parts by mass in Example 7 with respect to 100 parts by mass of the base resin. The insulated wires of Examples 5, 6 and 7 were produced using the same composition and the content ratio as in Example 3 except that they were blended in the catalyst batch.

[Example 8]
The aluminum hydroxide particles and magnesium hydroxide particles (trade name: Kisuma 5 Kyowa Chemical Industry Co., Ltd.) used in Example 1 for the flame retardant batch were hydroxylated with respect to 100 parts by mass of the base resin at a mass ratio of 50:50. Insulation of Example 8 using the same composition and content ratio as in Example 1 except that the total content of aluminum particles and magnesium hydroxide particles was 160 parts by mass in the flame retardant batch. An electric wire was manufactured.

[Comparative Example 1]
160 parts by mass of aluminum hydroxide particles (trade name: Heidilite H42 Showa Denko Co., Ltd.) having a mass reduction rate of 0.3% when heated from 110 ° C. to 210 ° C. with respect to 100 parts by mass of the base resin The insulated wire of the comparative example 1 was manufactured using the composition similar to Example 1, and its content ratio except having mix | blended with the flame retardant batch so that it might become quantity.

[Comparative Examples 2 and 3]
The aluminum hydroxide particles used in Example 1 were added to the flame retardant batch so that the content was 100 parts by mass in Comparative Example 2 and 260 parts by mass in Comparative Example 3 with respect to 100 parts by mass of the base resin. Insulated wires of Comparative Examples 2 and 3 were produced using the same composition and content ratio as in Example 1.

[Reference example]
Except for blending magnesium hydroxide particles (trade name: Kisuma 5 Kyowa Chemical Industry Co., Ltd.) in place of aluminum hydroxide particles in a flame retardant batch so as to have a content of 160 parts by mass with respect to 100 parts by mass of the base resin, The insulated wire of the reference example was manufactured using the composition similar to Example 1, and its content ratio.

  In addition, the maximum extrusion linear velocity of Examples 2-7, Comparative Examples 1-3, and a reference example is as showing in Table 1. However, in Comparative Example 2, a smooth sheath layer having no defects such as irregularities could not be formed on the surface even when the linear velocity was minimized (10 m / min).

  About each obtained insulated wire of Examples 1-7, Comparative Examples 1-3, and a reference example, tensile strength and tensile elongation were measured, respectively. In addition, flame retardancy and low temperature flexibility were tested. These results are shown in Table 1.

  As shown from the results in Table 1, the insulated wires of Examples 1 to 7 are excellent in tensile strength, tensile elongation and flame retardancy while using aluminum hydroxide as a flame retardant instead of magnesium hydroxide, Formability is also good. Moreover, Examples 1-3 and 5-7 which used VLDPE for base resin are excellent also in low-temperature flexibility, and can be used conveniently also in a cold district.

  As described above, the insulated wire using the silane crosslinkable resin composition of the present invention can promote reduction in manufacturing cost while maintaining various properties such as flame retardancy. Therefore, the said insulated wire can be used suitably as a cable which transmits the electric power generated with the solar cell module to the exterior, for example.

Claims (6)

A silane crosslinkable resin composition comprising a base resin mainly composed of polyethylene and / or ethylene-polar monomer copolymer and a non-halogen flame retardant, wherein the non-halogen flame retardant contains aluminum hydroxide particles,
The proportion of aluminum hydroxide particles in the non-halogen flame retardant is 50% by mass or more,
The mass reduction rate when the aluminum hydroxide particles are heated from 110 ° C. to 210 ° C. is 0.15% or less,
Content of the said aluminum hydroxide particle with respect to 100 mass parts of said base resins is 110 to 250 mass parts, The silane crosslinkable resin composition characterized by the above-mentioned.   The silane crosslinkable resin composition according to claim 1, wherein the polyethylene is ultra-low density polyethylene. Further containing a modified silicone compound containing a carbon-carbon double bond;
The content of the modified silicone compound with respect to 100 parts by mass of the base resin is 0.1 parts by mass or more and 10 parts by mass or less,
The silane crosslinkable resin composition according to claim 1 or 2, wherein the modified silicone compound has at least one selected from the group consisting of a vinyl group, an acrylic group, and a methacryl group at at least one terminal. An insulated wire comprising a conductor, an insulating layer covering the peripheral surface of the conductor, and a sheath layer covering the periphery of the insulating layer,
An insulated wire, wherein the sheath layer is formed from the silane crosslinkable resin composition according to claim 1, claim 2, or claim 3. An insulated wire comprising a conductor, an insulating layer covering the peripheral surface of the conductor, and a sheath layer covering the periphery of the insulating layer,
The sheath layer is formed from a silane crosslinkable resin composition containing a base resin mainly composed of polyethylene and / or ethylene-polar monomer copolymer and a non-halogen flame retardant,
The non-halogen flame retardant contains aluminum hydroxide particles,
The proportion of aluminum hydroxide particles in the non-halogen flame retardant is 50% by mass or more,
Content of the said aluminum hydroxide particle with respect to 100 mass parts of said base resins is 110 mass parts or more and 250 mass parts or less,
Tensile strength is 8 MPa or more,
An insulated wire having a tensile elongation of 125% or more. A method for producing an insulated wire comprising a conductor, an insulating layer covering the peripheral surface of the conductor, and a sheath layer covering the periphery of the insulating layer,
Insulation comprising: a step of laminating the silane crosslinkable resin composition according to claim 1, 2 or 3 on a peripheral surface of the insulating layer; and a step of crosslinking the silane crosslinkable resin composition. Electric wire manufacturing method.