JP2017191700A - Insulated wire and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulated wire that is excellent in flexibility, heat resistance, strength, and conductivity of a conductor, the conductor obtained by bringing an organic fiber into conduction, and a method for producing the same.SOLUTION: An insulated wire 10 has a conductor 12 comprising a core wire made up of conductive monofilaments, and an insulating layer 14 provided around the conductor 12. The conductive monofilaments comprise crystalline polyester and noncrystalline polyester as a base resin, comprise carbon nanotubes as a conductive filler, and has a breaking strength of 50 MPa or more and a volume resistance of 100 Ω cm or less. A conductive composition comprising crystalline polyester, noncrystalline polyester, and carbon nanotubes is used to perform spinning to make the conductor 12 comprising a core wire made up of conductive monofilaments.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an insulated wire and a method for producing an insulated wire, and more particularly to an insulated wire suitable as a thin wire and a method for producing the insulated wire.

Conventionally, an insulated wire having an insulating layer on the outer periphery of a conductor made of a twisted metal wire is known. For example, a thin insulated wire having a conductor cross-sectional area of 0.13 mm ² has a low tensile strength and is easily broken. Moreover, since the stiffness is weak, it is easy to buckle when inserted into the connector. In particular, a conductor made of a stranded metal wire is made of twisted thin metal wires, which improves flexibility but leads to a decrease in strength and buckling resistance. Thus, for example, in Patent Document 1, an attempt is made to improve the flexibility, strength, and buckling resistance by making organic fibers conductive and applying them as conductors.

Japanese Unexamined Patent Publication No. 2014-150022

  When a metal material is plated around the organic fiber, the adhesion between the organic material and the metal material is low, so that the plating is easily peeled off. In order to avoid providing a metal layer around the organic fiber, it is preferable that the organic fiber itself be sufficiently conductive to be a conductor of an insulated wire. However, for example, when a conductive single fiber is prepared by blending a conductive filler with PET resin and this is used as a conductor of an insulated wire, it becomes too hard to obtain a desired conductivity and is inferior in flexibility. Further, for example, when a conductive single fiber is prepared by blending a polyolefin-based resin with a conductive filler and used as a conductor of an insulated wire, it is difficult to provide an insulating coating on the outer periphery because of low heat resistance.

  The problem to be solved by the present invention is to provide an insulated wire excellent in the flexibility, heat resistance, strength, and conductivity of a conductor obtained by making organic fibers conductive, and a method for producing the same.

  In order to solve the above problems, an insulated wire according to the present invention includes a conductor composed of a core wire of a conductive single fiber and an insulating layer provided on the outer periphery of the conductor, and the conductive single fiber is used as a base resin. The gist of the invention is that it contains crystalline polyester and non-crystalline polyester, contains carbon nanotubes as a conductive filler, has a breaking strength of 50 MPa or more, and a volume resistivity of 100 Ω · cm or less.

  The ratio of the amorphous polyester is preferably in the range of 10 to 30% by mass with respect to the total of the crystalline polyester and the amorphous polyester. The carbon nanotube content is preferably in the range of 5 to 30 parts by mass with respect to 100 parts by mass of the base resin of the conductive single fiber. The outer diameter of the conductive single fiber is preferably in the range of 0.1 to 2.0 mm.

  And the manufacturing method of the insulated wire which concerns on this invention spin-processes using the electroconductive composition which contains crystalline polyester and non-crystalline polyester as a base resin, and contains a carbon nanotube as an electroconductive filler. The gist is to have a step of producing a conductor made of a core wire.

  In this case, it is preferable to perform spinning at a wire speed of 1000 m / min or more.

  According to the insulated wire according to the present invention, a conductive filler is added to the organic fiber to make it conductive, and the conductor is formed using this, so it is necessary to form a metal layer on the outer periphery of the organic fiber. And the problem of peeling of the metal layer can be suppressed. Moreover, since the conductor core wire is comprised with the single fiber, the buckling at the time of inserting in a connector is suppressed. And since crystalline polyester is used for the base resin of organic fiber, heat resistance and intensity | strength are ensured and buckling is also suppressed. By including non-crystalline polyester in addition to crystalline one, it becomes easy to take in the conductive filler and the dispersibility is improved. Thereby, the quantity of the conductive filler for obtaining desired electroconductivity can be decreased. Since carbon nanotubes are used as the conductive filler, the conductive fillers are easily in contact with each other, and the amount of the conductive filler for obtaining desired conductivity can be reduced. Since the bundle of carbon nanotubes can be unwound or stretched by utilizing the crystalline orientation of the crystalline polyester when processed into a fiber, the amount of conductive filler for obtaining the desired conductivity can be reduced. Can be reduced. Thereby, it is excellent in a flexibility, ensuring electroconductivity and intensity | strength.

  And when the ratio of non-crystalline polyester is in a specific range, it is excellent in balance of strength, flexibility and buckling resistance. Further, when the content of the carbon nanotube is within a specific range, the balance of conductivity, strength, and flexibility is excellent. And it is easy to ensure the excellent bending property, intensity | strength, and buckling resistance also in a thin diameter electric wire because the outer diameter of an electroconductive single fiber exists in the range of 0.1-2.0 mm.

  Then, according to the method for manufacturing an insulated wire according to the present invention, a conductive composition is obtained by spinning using a conductive composition containing crystalline polyester and amorphous polyester as a base resin and carbon nanotubes as a conductive filler. Since it has the process of producing the conductor which consists of a fiber core wire, the insulated wire which is excellent in the flexibility of a conductor, heat resistance, intensity | strength, and electroconductivity can be manufactured in the conductor formed by making organic fiber conductive.

  When spinning is performed at a linear speed of 1000 m / min or more, the crystal orientation of the crystalline polyester is increased during the spinning process, and the bundle of carbon nanotubes is easily unraveled. Thereby, since the quantity of the conductive filler for obtaining desired electroconductivity can be decreased, it becomes more excellent in flexibility, ensuring electroconductivity and intensity | strength.

It is radial direction sectional drawing of the insulated wire which concerns on one Embodiment of this invention. It is the graph which showed the relationship between the line speed of a spinning process, breaking strength, and volume resistivity.

  Next, an embodiment of the present invention will be described in detail. FIG. 1 is a radial cross-sectional view of an insulated wire according to an embodiment of the present invention.

  As shown in FIG. 1, an insulated wire 10 according to an embodiment of the present invention includes a conductor 12 and an insulating layer 14 provided on the outer periphery of the conductor 12. The conductor 12 is made of a conductive single fiber (monofilament) core wire. In the insulated wire 10, the insulating layer 14 is disposed in contact with the conductor 12.

  The conductive single fiber includes crystalline polyester and amorphous polyester as a base resin, and carbon nanotubes as a conductive filler. The conductive single fiber has the above composition, and has a breaking strength of 50 MPa or more and a volume resistivity of 100 Ω · cm or less. When the breaking strength is 50 MPa or more, the strength is excellent. The breaking strength is measured based on the JISK7161 tensile test. When the volume resistivity is 100 Ω · cm or less, the conductivity is excellent, and the conductivity necessary for the electric wire conductor can be ensured with only the conductive single fiber.

  More preferably, the conductive single fiber has a breaking strength of 100 MPa or more. More preferably, it is 300 MPa or more, and particularly preferably 500 MPa or more. Further, the conductive monofilament preferably has a volume resistivity of 50 Ω · cm or less. More preferably, it is 10 Ω · cm or less. Moreover, it is preferable that the outer diameter of an electroconductive single fiber exists in the range of 0.1-2.0 mm. Thereby, it is easy to ensure excellent flexibility, tensile strength, and buckling resistance even in a thin wire.

  Since crystalline polyester is relatively excellent in strength, it is possible to ensure the strength and buckling resistance of conductive single fibers. Further, from the viewpoint of strength, buckling resistance, etc., the crystalline polyester preferably has a high crystal orientation in the fiber direction of the conductive single fiber. Then, by utilizing the crystal orientation of the crystalline polyester, the carbon nanotubes (CNTs) described later are easily oriented in the fiber direction of the conductive single fibers, and the carbon nanotubes are easily brought into contact with each other. Thereby, the addition amount for obtaining desired electroconductivity can be decreased. If it does so, the fall of the workability to fiber form by containing a conductive filler, the fall of flexibility, and the fall of intensity | strength are suppressed. Further, by utilizing the crystal orientation of the crystalline polyester, the bundle of carbon nanotubes can be easily solved. Thereby, the addition amount for obtaining desired electroconductivity can be decreased.

  Examples of the crystalline polyester include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN). These may be used alone or in combination of two or more. Among these, polyethylene terephthalate is preferable from the viewpoints of being relatively inexpensive, easily crystallized, and easily improving the breaking strength.

  Amorphous polyester is softer than crystalline polyester and more easily incorporates conductive fillers. Thereby, since the dispersibility of an electroconductive filler improves, the addition amount for obtaining desired electroconductivity can be decreased. If it does so, the fall of the workability to fiber form by containing a conductive filler, the fall of flexibility, and the fall of intensity | strength are suppressed.

  Examples of the non-crystalline polyester include terephthalic acid, ethylene glycol, and terpolymer-type polyethylene terephthalate copolymers of other compositions. These may be used alone or in combination of two or more.

  The ratio of the amorphous polyester is preferably 10 parts by mass or more with respect to the total of the crystalline polyester and the amorphous polyester. More preferably, it is 15 parts by weight or more. When the proportion of the amorphous polyester is 10 parts by mass or more, the conductive filler dispersion effect is excellent. Moreover, it is preferable that the ratio of non-crystalline polyester is 30 mass parts or less with respect to the sum total of crystalline polyester and non-crystalline polyester. More preferably, it is 25 parts by weight or less. It is easy to ensure the said characteristic of crystalline polyester as the ratio of amorphous polyester is 30 mass parts or less.

  Carbon nanotubes (CNT) are blended in the base resin as a conductive filler, improve the conductivity of the conductive single fiber, and can ensure the necessary conductivity as a wire conductor with only the conductive single fiber. By using carbon nanotubes as the conductive filler, the conductive fillers can easily come into contact with each other, and the amount of the conductive filler for obtaining desired conductivity can be reduced.

  The content of the carbon nanotube is preferably 5 parts by mass or more with respect to 100 parts by mass of the base resin of the conductive single fiber from the viewpoint of easily ensuring excellent conductivity. More preferably, it is 15 parts by mass or more. In addition, from the viewpoint of easily reducing the processability to a fibrous shape due to the inclusion of the conductive filler, the decrease in flexibility, and the decrease in strength, it is 30% with respect to 100 parts by mass of the base resin of the conductive single fiber. Part or less. More preferably, it is 25 mass parts or less, More preferably, it is 20 mass parts or less. And when content of a carbon nanotube is in the range of 5-30 mass parts with respect to 100 mass parts of base resin of a conductive single fiber, it is excellent in the balance of electroconductivity, intensity | strength, and flexibility.

  The conductive single fiber may contain other components in addition to the crystalline polyester, the amorphous polyester, and the carbon nanotube as long as the object of the present invention is not impaired. Examples of other components include flame retardants, antioxidants, metal deactivators (copper damage inhibitors), lubricants, anti-aging agents, ultraviolet absorbers, nucleating agents, and dispersants. However, if other fillers are included in addition to the conductive filler, the processability to a fibrous shape is reduced, so it is preferable not to include other fillers.

  The material of the insulating layer 14 is not particularly limited. Any insulating material used as a wire covering material may be used. Non-halogens that do not have halogen atoms, such as homopolymers of olefins such as ethylene and propylene, copolymers of ethylene and α-olefins, copolymers of olefins with (meth) acrylic acid esters, vinyl acetate, etc. It may be a system material or a halogen system material such as vinyl chloride resin. The insulating material may contain various additives in addition to the resin component.

  The conductive single fiber can be produced by spinning using a conductive composition containing crystalline polyester and amorphous polyester as the base resin and carbon nanotubes as the conductive filler. The manufacturing method of the insulated wire which concerns on this invention has the process of producing the conductor which consists of a core wire of such an electroconductive single fiber.

  In the spinning process, it is preferable to increase the crystal orientation of the crystalline polyester in the fiber direction. For this purpose, for example, the linear speed of the spinning process is preferably increased. At this time, since the action of stretching the bundle of carbon nanotubes in the fiber direction is greatly generated, the bundle of carbon nanotubes is easily unraveled. When the bundle of carbon nanotubes is released, the carbon nanotubes are easily oriented in the fiber direction in the spinning process. If it does so, since it will become easy to contact carbon nanotubes, even if it reduces a compounding quantity, the quantity of the conductive filler for obtaining desired electroconductivity can be decreased. From the above viewpoint, in the spinning process, the linear velocity is preferably 1000 m / min or more. More preferably, it is 1500 m / min or more, More preferably, it is 2000 m / min or more. Moreover, the bundle of carbon nanotubes can also be unraveled in advance by irradiating the conductive composition containing carbon nanotubes with ultrasonic waves before spinning. This also makes it easy to orient the carbon nanotubes in the fiber direction during the spinning process.

  The outer periphery of the conductor 12 made of a conductive single fiber core wire is covered with an insulating layer 14 by extrusion or the like. Thereby, the insulated wire 10 can be manufactured. Since the conductive single fiber base resin contains crystalline polyester and is excellent in heat resistance, an insulating coating used as a wire coating such as vinyl chloride resin can be provided.

  According to the insulated wire 10 having the above configuration, the conductive layer 12 is made conductive by adding a conductive filler to the organic fiber, and the conductor 12 is formed using this, so that a metal layer is formed on the outer periphery of the organic fiber. Therefore, the problem of peeling of the metal layer can be suppressed. Moreover, since the conductor core wire is comprised with the single fiber, the buckling at the time of inserting in a connector is suppressed. In addition, there is no gap between the conductor 12 and the insulating layer 14, and water is not sucked up from the gap between the conductor 12 and the insulating layer 14, and the water stop effect is high. And since crystalline polyester is used for the base resin of organic fiber, heat resistance and intensity | strength are ensured and buckling is also suppressed. By including non-crystalline polyester in addition to crystalline one, it becomes easy to take in the conductive filler and the dispersibility is improved. Thereby, the quantity of the conductive filler for obtaining desired electroconductivity can be decreased. Since carbon nanotubes are used as the conductive filler, the conductive fillers are easily in contact with each other, and the amount of the conductive filler for obtaining desired conductivity can be reduced. Since the bundle of carbon nanotubes can be unwound or stretched by utilizing the crystalline orientation of the crystalline polyester when processed into a fiber, the amount of conductive filler for obtaining the desired conductivity can be reduced. Can be reduced. Thereby, it is excellent in a flexibility, ensuring electroconductivity and intensity | strength.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited by an Example.

(Relationship between spinning speed and strength / conductivity)
The relationship between the spinning speed, breaking strength, and volume resistivity was investigated. It shows in the following Table 1 and FIG.

<Preparation of conductive single fiber>
80 parts by mass of crystalline polyester as a base resin and 20 parts by mass of an amorphous polyester were blended, and 15 parts by mass of carbon nanotubes as a conductive filler was blended with respect to 100 parts by mass of the base resin. This conductive composition was heat-kneaded and then spun into a fiber diameter of 0.5 mm at a predetermined linear velocity. In this way, a conductive single fiber was produced.
-Crystalline polyester "NOVAPEX G5" manufactured by Mitsubishi Chemical
・ Non-crystalline polyester "NOVAPEX I3" manufactured by Mitsubishi Chemical
・ Carbon nanotubes (CLONO “FLOTUBE 9000F”)

  From Table 1 and FIG. 2, it can be seen that the breaking strength improves as the spinning speed increases. It can also be seen that the volume resistivity decreases as the spinning speed increases. The improvement in the breaking strength is presumed to be due to the fact that the crystalline orientation of the crystalline polyester increases as the spinning speed increases. The decrease in volume resistivity means that the crystal orientation of the crystalline polyester becomes higher as the spinning speed increases, and the carbon nanotube bundle is stretched in the fiber direction along with this, and the carbon nanotube bundle is unwound. This is presumably because the carbon nanotubes are oriented in the fiber direction, and the carbon nanotubes are easily in contact with each other. From the results of Table 1 and FIG. 2, it can be seen that, for example, when the spinning speed is 1000 m / min or more, the effect of improving the breaking strength and the effect of reducing the volume resistivity are excellent. Furthermore, it can be seen that the effect of improving the breaking strength and the effect of reducing the volume resistivity are particularly excellent by setting the linear speed of the spinning process to 1500 m / min or more.

(Example 1-5)
<Preparation of conductive single fiber>
After blending a base resin (crystalline polyester and non-crystalline polyester) and a conductive filler (carbon nanotube) with the blending composition (parts by mass) shown in Table 2, the conductive composition is heated and kneaded, and then given. Spinning was performed to a fiber diameter of 0.5 mm at a linear speed of. In this way, a conductive single fiber was produced.
・ Crystalline polyester: "NOVAPEX G5" manufactured by Mitsubishi Chemical
Non-crystalline polyester: “NOVAPEX I3” manufactured by Mitsubishi Chemical
・ Carbon nanotube: “FLOTUBE 9000F” manufactured by CNANO

<Production of insulated wires>
The obtained conductive single fiber was used as a conductor core wire, and a vinyl chloride resin composition was coated on the outer periphery by extrusion coating to produce an insulated wire.

(Comparative Example 1)
In the production of conductive single fibers, conductive single fibers and insulated wires were produced in the same manner as in Example except that amorphous polyester was not used as the base resin and the base resin was changed to 100% by mass of crystalline polyester.

(Comparative Example 2)
In the production of conductive single fibers, conductive single fibers and insulated wires were produced in the same manner as in Example except that the base resin was changed to 100% by mass of polyolefin instead of polyester.
Polyolefin: polyethylene (Sumitomo Chemical "Sumikasen-G701", density 0.919 g / cm ³ , MFR 7 g / 10 min)

(Comparative Example 3)
In the production of conductive single fibers, conductive single fibers and insulated wires were produced in the same manner as in Example except that polyolefin was used as the base resin in addition to crystalline polyester and non-crystalline polyester.

(Comparative Example 4)
In the production of the conductive single fiber, a conductive single fiber and an insulated wire were prepared in the same manner as in the example except that the crystalline polyester was not used as the base resin and the base resin was changed to 100% by mass of the amorphous polyester.

  The produced conductive single fibers were evaluated for heat resistance, breaking strength, and conductivity (volume resistivity). Moreover, the flexibility was evaluated using the produced insulated wire.

(Flexibility)
In the mandrel type 120 ° double-side bending test, the sample was bent 100 reciprocally at a bending radius r = 8 mm and a repetition rate of 120 rpm. At this time, the case where disconnection was not confirmed was determined as “good”, and the case where disconnection was confirmed was determined as “bad”.

(Heat-resistant)
The produced conductive monofilament 600 mm was suspended in a bath at 200 ° C., a 50 g weight was fixed to the tip, taken out after being left for 2 hr, and the wire length was measured. If the conductive single fiber was not broken and the line length did not increase by 5% or more after the test, it was judged as “good”, and the case where the fracture or the line length increased by 5% or more was judged as “bad”.

(Breaking strength)
Based on JISK7161, it measured with the general purpose tensile testing machine. 50 MPa or more was judged as acceptable “◯”, and 500 MPa or more as good “良好”. Less than 50 MPa was regarded as a failure “x”.

(Conductivity (volume resistivity))
Based on JISK6271, the volume specific resistance value of the conductive fibers was measured. 100 Ω · cm or less was accepted as “good”, and 10 Ω · cm or less was judged as “good”.

  From Comparative Example 1, it can be seen that if the base resin of the conductive single fiber is only crystalline polyester, the flexibility is not satisfied in order to satisfy the desired conductivity. From Comparative Example 2, if the base resin of the conductive single fiber is non-crosslinked polyolefin, the heat resistance is not satisfied, and it may be difficult to provide an insulating coating. Also, the breaking strength is not satisfied. From Comparative Example 3, if the conductive single fiber base resin contains a large amount of non-crosslinked polyolefin, the heat resistance is not satisfied, and it may be difficult to provide an insulating coating. Also, the breaking strength is not satisfied. From Comparative Example 4, if the base resin of the conductive single fiber is only amorphous polyester, the heat resistance and breaking strength are not satisfied. On the other hand, the example uses the characteristics shown in FIG. 2 and uses a non-crystalline polyester together with a crystalline polyester as a base resin for conductive single fibers, and uses carbon nanotubes as a conductive filler, thereby providing flexibility and heat resistance. , Breaking strength and electrical conductivity (volume resistivity) could be satisfied.

  From Examples 1 and 4 and Comparative Example 1, in the base resin, when the ratio of the amorphous polyester is 20 parts by mass or less with respect to the total of the crystalline polyester and the amorphous polyester, the breaking strength may be improved. Recognize. Further, Examples 2 and 4 show that the breaking strength and the conductivity are improved when the linear velocity is 1500 MPa or more.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

10 Insulated wire 12 Conductor 14 Insulating layer

Claims (6)

A conductor composed of a core wire of conductive monofilament, and an insulating layer provided on the outer periphery of the conductor,
Insulation characterized in that the conductive single fiber includes crystalline polyester and amorphous polyester as a base resin, carbon nanotubes as a conductive filler, and has a breaking strength of 50 MPa or more and a volume resistivity of 100 Ω · cm or less. Electrical wire.   2. The insulated wire according to claim 1, wherein a ratio of the amorphous polyester is in a range of 10 to 30 mass% with respect to a total of the crystalline polyester and the amorphous polyester.   The insulated wire according to claim 1 or 2, wherein the content of the carbon nanotube is in the range of 5 to 30 parts by mass with respect to 100 parts by mass of the base resin of the conductive single fiber.   The insulated wire according to any one of claims 1 to 3, wherein an outer diameter of the conductive single fiber is in a range of 0.1 to 2.0 mm. A method for manufacturing an insulated wire according to any one of claims 1 to 4,
Characterized in that it has a step of producing a conductor comprising a core wire of a conductive single fiber by spinning using a conductive composition containing crystalline polyester and amorphous polyester as a base resin and containing carbon nanotubes as a conductive filler. A method for manufacturing an insulated wire.   The method for producing an insulated wire according to claim 5, wherein the spinning process is performed at a linear speed of 1000 m / min or more.

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