JP2009245652A - Insulated wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulated wire capable of suppressing charge degradation under a high temperature environment and increasing a charge life. <P>SOLUTION: The insulated wire T1 includes a first resin layer 1 coating the periphery of a conductor 4 and a second resin layer 2 coating the periphery of the first resin layer 1. The first resin layer 1 has a relative dielectric constant ε1; and the second resin layer 2 has a relative dielectric constant ε2. The relative dielectric constants ε1 and ε2 satisfy the relationship of ε1/ε2>1 or preferably ε1/ε2>1.1 at a temperature of 150°C or higher. The first and second resin layers 1 and 2 are made of substances selected from an amorphous resin whose glass transition temperature (Tg) is 150°C or higher and a crystalline resin whose melting point (Tm) is 150°C or higher. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an insulated wire obtained by coating an outer periphery of a conductor with at least two layers of an insulating film, and more particularly to an insulated wire suitable for use in a high-temperature environment such as an automobile.

  As shown in Patent Document 1, for example, a conventional insulated wire is configured by covering a conductor with an insulating film.

The conductor is made of a conductive metal such as copper or aluminum, and the insulating film is made of an insulating resin, for example.
Japanese Patent Laid-Open No. 2005-268082

  FIG. 7 is a graph showing current characteristics in a high temperature applied state in the case of an insulated wire coated with a polyphenylene sulfide (PPS) resin.

  From FIG. 7, it can be seen that as the temperature increases, a current (indicated by a solid line) flows that is larger than the current derived from Ohm's law (indicated by a dotted line).

  For this reason, the conventional insulated wires have a problem in that the degradation of electricity under a high temperature environment is large and the life of electricity is short.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an insulated wire that can suppress the degradation of electricity under a high temperature environment and can improve the life of electricity.

The inventors of the present invention have found that the degradation and life of an insulated wire under a high temperature environment such as an automobile are greatly influenced by charge injection (Schottky emission) from the electrode.
In general, the Schottky emission current i is expressed by the following equation.

Here, A is the Richardson-Dashman constant, T is the absolute temperature, E is the electric field, φ _D is the work function for the metal dielectric, and k is the Boltzmann constant.

  In other words, electrical conduction is dominant in charge injection from the electrode in a high temperature environment, and when a large electric field is applied to the electrode surface, charge injection is further promoted, and a rapid current increase degrades the resin and leads to dielectric breakdown. is there.

Therefore, the insulated wire of the present invention is an insulated wire formed by coating an outer periphery of a conductor with at least two layers of an insulating film.
A first resin layer having a relative dielectric constant ε1 coated on the outer periphery of the conductor;
A second resin layer having a relative dielectric constant ε2 coated on the outer periphery of the first resin layer,
At 150 ° C. or higher, ε1 / ε2> 1
It is characterized by this.

  It is desirable that ε1 / ε2> 1.1 at 150 ° C. or higher.

  The thickness of the first resin layer may be greater than 0% and 30% or less of the total thickness of the first resin layer and the second resin layer.

  The thickness of the first resin layer is preferably greater than 0% and not more than 20% of the total thickness of the first resin layer and the second resin layer.

  The first resin layer and the second resin layer may be made of a material selected from an amorphous resin having a glass transition temperature of 150 ° C. or higher or a crystalline resin having a melting point of 150 ° C. or higher.

A third resin layer having a relative dielectric constant ε3 coated on the outer periphery of the second resin layer;
At 150 ° C. or higher, ε3 / ε2> 1 may be satisfied.

  It is desirable that the relationship is ε3 / ε2> 1.1 at 150 ° C. or higher.

  The total thickness of the first resin layer and the third resin layer is more than 0% of the total thickness of the first resin layer, the second resin layer, and the third resin layer. It may be large and 30% or less.

The total thickness of the first resin layer and the third resin layer is more than 0% of the total thickness of the first resin layer, the second resin layer, and the third resin layer. It is desirable to be large and 20% or less.
The third resin layer may be made of a material selected from an amorphous resin having a glass transition temperature of 150 ° C. or higher or a crystalline resin having a melting point of 150 ° C. or higher.
A deterioration preventing layer for preventing deterioration of the resin layer due to the conductor may be formed between the conductor and the first resin layer.

  According to the first aspect of the present invention, the second resin layer is coated at the outer periphery of the first resin layer with the relative dielectric constant ε1 of the first resin layer adjacent to the conductor surface at 150 ° C. or higher. Therefore, the electric field on the conductor surface can be reduced, and the charge injection into the insulated wire can be suppressed. As a result, it is possible to suppress the degradation of electricity under a high temperature environment and to improve the life of electricity.

  According to the second aspect of the present invention, since the relative dielectric constant ε1 becomes higher than the relative dielectric constant ε2, the voltage reduction effect is further improved.

  According to the invention of claim 3, since the first resin layer having a high dielectric constant is thin, an increase in the electric field applied to the second resin layer can be suppressed, so that the breakdown voltage characteristics are not impaired.

  In addition, when an air gap is involved, an increase in the electric field of the air gap can be suppressed, so that the inverter surge resistance (corona start voltage) characteristics are not impaired.

  According to the invention of claim 4, since the first resin layer is further thin, the breakdown voltage characteristics and the inverter surge resistance characteristics are further improved.

  According to the invention which concerns on Claim 5, the said effect can be show | played more reliably.

  According to the sixth aspect of the invention, the relative dielectric constant ε3 of the third resin layer coated on the outer periphery of the second resin layer at 150 ° C. or higher is higher than that of the second resin layer. Therefore, charge injection into the insulated wire can be suppressed. As a result, it is possible to suppress the degradation of electricity under a high temperature environment and to improve the life of electricity.

  According to the seventh aspect of the present invention, since the relative dielectric constant ε3 becomes higher than the relative dielectric constant ε2, the voltage reduction effect is further improved.

  According to the invention of claim 8, since the first resin layer and the third resin layer having a high dielectric constant are thin, the electric field applied to the second resin layer is reduced, and the breakdown voltage characteristics are not impaired. .

  In addition, when an air gap is involved, an increase in the electric field of the air gap can be suppressed, so that the inverter surge resistance (corona start voltage) characteristics are not impaired.

  According to the ninth aspect of the invention, since the first resin layer and the third resin layer are thinner, the dielectric breakdown voltage characteristics and the inverter surge resistance characteristics are further improved.

  According to the invention which concerns on Claim 10, the said effect can be show | played more reliably.

  According to the invention which concerns on Claim 11, the oxidation deterioration promotion effect | action of resin by the contact with a metal can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1A and 1B are cross-sectional views showing an insulated wire according to a first embodiment of the present invention. FIG. 1A shows a case where the cross section is round, and FIG. 1B shows a case where the cross section is square.

  As shown in FIGS. 1A and 1B, the insulated wire T1 according to the first embodiment of the present invention includes a first resin layer 1 having a relative dielectric constant ε1 coated on the outer periphery of a conductor 4 and And the second resin layer 2 having a relative dielectric constant ε2 coated on the outer periphery of the first resin layer 1, and ε1 / ε2> 1, preferably ε1 / ε2> 1.1 at 150 ° C. or higher. It is characterized by having a relationship.

  The conductor 4 is made of a conductive metal such as copper or aluminum.

  The first resin layer 1 and the second resin layer 2 are made of a material selected from an amorphous resin having a glass transition temperature (Tg) of 150 ° C. or higher or a crystalline resin having a melting point (Tm) of 150 ° C. or higher. It has been.

  Examples of the amorphous resin having a glass transition temperature of 150 ° C. or higher include polyimide (PI), polyamideimide (PAI), polyesterimide, polyetherimide (PEI), polyimide hydantoin-modified polyester, and polyethersulfone (PES). , Polysulfone (PSU), polyphenylsulfone (PPSU) polyarylate (PAR), and the like. These plural copolymers and plural polymer alloys are also included.

  Examples of the crystalline resin having a melting point of 150 ° C. or higher include polyphenylene sulfide (PPS), polymethylpentene (PMP), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetra Fluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), polyamide 6, 66, 11, 12, 610, 46 aliphatic polyamide, polyamide 6T, 9T, MXD6 , Aromatic polyamides containing polyphthalamide, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBT), polybutylene naphthalate (PBN), polyphenylene ether (PPE), polyphenylene oxide (PPO), polyether ether ketone (PEEK), aromatic polyester including liquid crystal polymer (LCP), syndiotactic polystyrene (SPS), polyacetal (POM), etc. Can be mentioned. These plural copolymers and plural polymer alloys are also included.

In addition, in order to raise the dielectric constant of the 1st resin layer 1 using the resin of the same composition as the 1st resin layer 1 and the 2nd resin layer 2, carbon, silica ( A filler such as SiO ₂ ), titanium oxide (TiO ₂ ), or alumina (Al ₂ O ₃ ) may be added.

  FIG. 2 is an explanatory diagram showing a state in which the voltage V is applied to the insulated wire T1 (see FIG. 1B) according to the first embodiment of the present invention.

When the relative dielectric constant of the first resin layer 1 is ε1, the thickness is Ta, the relative dielectric constant of the second resin layer 2 is ε2, and the thickness is Tb, the electric field E on the conductor surface is
E = ε2 × V / (ε1 × Tb + ε2 × Ta)
It becomes.

  In a high temperature environment of 150 ° C. or higher, charge injection from the voltage V depends on the electric field E on the surface of the conductor 4, so that the charge injection can be suppressed by reducing the electric field E on the surface of the conductor 4. In order to reduce the electric field on the surface of the conductor 4, the dielectric constant of the first resin layer 1 adjacent to the conductor 4 may be increased.

  According to the insulated wire T1 according to the first embodiment of the present invention, the relative dielectric constant ε1 of the first resin layer 1 adjacent to the surface of the conductor 4 at 150 ° C. or higher is higher than that of the first resin layer 1. Since the relative dielectric constant ε2 of the second resin layer 2 coated on the outer periphery of the conductor 4 is higher, the electric field on the surface of the conductor 4 can be reduced, and charge injection into the insulated wire T1 can be suppressed. As a result, it is possible to suppress the degradation of electricity under a high temperature environment and to improve the life of electricity.

  The inventors use a different material so that the relative dielectric constant ε1 of the first resin layer 1 is higher than the relative dielectric constant ε2 of the second resin layer 2 (Example (1)). To (4)), when the same material is used so that the relative dielectric constant ε1 of the first resin layer 1 is equal to the relative dielectric constant ε2 of the second resin layer 2 (Comparative Example (1)), the first The electric field on the surface of the conductor 4 when a different material is used so that the relative dielectric constant ε2 of the second resin layer 2 is higher than the relative dielectric constant ε1 of the resin layer 1 (comparative example (2)). Experiments to measure were performed.

  Table 1 shows the experimental results, the ratio with Comparative Example (1), and the electric field reduction effect.

この実験において、実施例（１）では、第１の樹脂層１としてＰＡＩ、第２の樹脂層２としてＰＰＳを用い、実施例（２）では、第１の樹脂層１としてＰＥＥＫ、第２の樹脂層２としてＰＰＳを用い、実施例（３）では、第１の樹脂層１としてＰＥＴ、第２の樹脂層２としてＰＰＳを用い、実施例（４）では、第１の樹脂層１としてＮｙ６６、第２の樹脂層２としてＰＰＳを用いた。

In this experiment, in Example (1), PAI was used as the first resin layer 1 and PPS was used as the second resin layer 2, and in Example (2), PEEK was used as the first resin layer 1, and the second resin layer 1 was used. PPS is used as the resin layer 2. In Example (3), PET is used as the first resin layer 1, PPS is used as the second resin layer 2, and Ny66 is used as the first resin layer 1 in Example (4). PPS was used as the second resin layer 2.

  In Comparative Example (1), PPS is used as the first resin layer 1 and the second resin layer 2, and in Comparative Example (2), PPS is used as the first resin layer 1, and Ny66 is used as the second resin layer 2. Using.

  The thickness Ta of the first resin layer 1 was 10 μm, the thickness Tb of the second resin layer 2 was 90 μm, the total film thickness T (Ta + Tb) was 100 μm, and the applied voltage was 1.0 kV.

  From Table 1, it can be seen that in the case of Examples (1) to (4), the electric field on the surface of the conductor 4 is reduced by 10% or more compared to the case of Comparative Example (1). Therefore, when the relationship is ε1 / ε2> 1, more preferably ε1 / ε2> 1.1 at 150 ° C. or higher, charge injection into the insulated wire T1 can be suppressed, and charging in a high temperature environment is possible. It can be seen that deterioration can be suppressed and the service life can be improved.

  FIG. 3 is a graph showing the relationship between the ratio of the thickness Ta of the first resin layer 1 to the total film thickness T and the electric field reduction effect.

  As can be seen from FIG. 3, since the electric field reduction effect is reduced when the first resin layer 1 is thickened, the ratio of the thickness Ta of the first resin layer 1 to the total film thickness T is required to obtain the electric field reduction effect. Is 30% or less, and desirably 20% or less.

  In the case where the total film thickness T is reduced to 50 μm and the ratio between the thickness Ta of the first resin layer 1 and the thickness Tb of the second resin layer 2 is made the same (Example (5 )), And the first resin layer 1 was not formed, and an experiment was conducted to measure the electric field on the surface of the conductor 4 in the case of only the second resin layer 2 (Comparative Example (3)).

  Table 2 shows the ratio of the experimental result and Comparative Example (3).

表２からわかるように、全体膜厚を薄くしても、全体膜厚Ｔに対する第１の樹脂層１の厚さＴａの比率が同じであれば、同様の電界低減効果を奏する。

As can be seen from Table 2, even if the total film thickness is reduced, the same electric field reducing effect can be obtained as long as the ratio of the thickness Ta of the first resin layer 1 to the total film thickness T is the same.

  FIG. 4 is a graph showing the relationship between the ratio of the thickness Ta of the first resin layer 1 to the total film thickness T, the electric field applied to the second resin layer 2, and the electric field of the conductor 4 surface.

  Here, ε1 is 4.0, ε2 is 2.8, the applied voltage V is 1 kV, and the total film thickness is 100 μm.

  As can be seen from FIG. 4, when the first resin layer 1 having a high dielectric constant is thickened, the electric field applied to the second resin layer 2 is increased, which may reduce the dielectric breakdown voltage.

  Therefore, in order to suppress the electric field rise and not impair the dielectric breakdown voltage characteristics, the ratio of the thickness Ta of the first resin layer 1 to the total film thickness T is 30% or less, preferably 20% or less. Need to be formed.

  FIG. 5 is a graph showing the relationship between the ratio of the thickness Ta of the first resin layer 1 to the total film thickness T and the electric field increase rate of the air gap.

  Here, ε1 is 4.0, ε2 is 2.8, and the air gap is 30 μm.

  As can be seen from FIG. 5, when the first resin layer 1 having a high dielectric constant becomes thicker, the electric field in the air gap becomes higher, causing a decrease in the corona start voltage.

  Therefore, in order not to impair the inverter surge (corona start voltage) characteristics, the ratio of the thickness Ta of the first resin layer 1 to the total film thickness T is 30% or less, preferably 20% or less. Need to form.

  6A and 6B are cross-sectional views showing an insulated wire according to a second embodiment of the present invention. FIG. 6A shows a case where the cross section is round, and FIG. 6B shows a case where the cross section is square.

  The insulated wire T2 according to the second embodiment of the present invention has a relative dielectric constant ε3 covered on the outer periphery of the second resin layer 2 in addition to the first resin layer 1 and the second resin layer 2. It has the 3rd resin layer 3, and has the relationship of (epsilon) 3 / (epsilon) 2> 1 at 150 degreeC or more, Preferably it is the relationship of (epsilon) 3 / (epsilon) 2> 1.1.

  The third resin layer 3 is made of a material selected from an amorphous resin having a glass transition temperature of 150 ° C. or higher or a crystalline resin having a melting point of 150 ° C. or higher. Specific materials are the same as those of the first resin layer 1 and the second resin layer 2 described above.

  According to the insulated wire T2 according to the second embodiment of the present invention, the relative dielectric constant ε3 of the third resin layer 3 coated on the outer periphery of the second resin layer 2 is 150 ° C. or higher. Since the relative dielectric constant ε2 of the second resin layer 2 is higher, charge injection into the insulated wire T1 can be suppressed. As a result, it is possible to suppress the degradation of electricity under a high temperature environment and to improve the life of electricity.

  The total thickness (Ta + Tc) of the thickness Ta of the first resin layer 1 and the thickness Tc of the third resin layer 3 is determined by the first resin layer 1, the second resin layer 2, and the third resin layer 3. The total thickness T of the resin layers 3 is 30% or less, preferably 20% or less. As a result, the first resin layer 1 and the third resin layer 3 are considerably thinner than the second resin layer 2, so that the dielectric breakdown characteristics and the inverter surge resistance (corona start voltage) characteristics are not impaired.

  The present inventors use PAI as the first resin layer 1, PPS as the second resin layer 2, PAI as the third resin layer 3, the thickness Ta of the first resin layer 1, and the third resin. When the thickness Tc of the layer 3 is 5 μm and the thickness Tb of the second resin layer 2 is 90 μm (Example (6)), only the second resin layer 2 is formed, and the thickness Tb is 100 μm. (Comparative Example (4)) and the case where only the first resin layer 1 and the second resin layer 2 are formed and the thickness Ta is 10 μm and the thickness Tb is 90 μm (Comparative Example (5)) The experiment of measuring the electric field on the surface of the conductor 4 in FIG.

  Here, ε1 is 4.0, ε2 is 2.8, the applied voltage V is 1 kV, and the total film thickness is 100 μm.

  Table 3 shows the ratio of the experimental results and Comparative Example (4).

表３からわかるように、第１の樹脂層１、第２の樹脂層２及び第３の樹脂層３を形成した実施例（６）の場合は、第１の樹脂層１及び第２の樹脂層２を形成した場合（比較例（５））と同様に、第２の樹脂層２だけを形成した比較例（４）の場合に比べ、電界低減効果を奏する。

As can be seen from Table 3, in the case of Example (6) in which the first resin layer 1, the second resin layer 2, and the third resin layer 3 were formed, the first resin layer 1 and the second resin Similar to the case where the layer 2 is formed (Comparative Example (5)), the electric field reducing effect is achieved as compared with the case of the Comparative Example (4) where only the second resin layer 2 is formed.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical matters described in the claims. For example, a metal antioxidant layer made of a metal oxide or a coding layer may be formed between the conductor and the first resin layer in order to prevent metal oxidation.

  The insulated wire of the present invention is suitable for use in a high temperature environment such as an automobile.

It is sectional drawing which shows the insulated wire which concerns on the 1st Example of this invention, (A) shows the case where a cross section is a round shape, (B) shows the case where a cross section is a square. It is explanatory drawing which shows the state which applied the voltage V with respect to the insulated wire which concerns on the 1st Example of this invention. It is a graph which shows the relationship between the ratio of the thickness Ta of the 1st resin layer with respect to the whole film thickness T, and an electric field reduction effect. 6 is a graph showing the relationship between the ratio of the thickness Ta of the first resin layer to the total film thickness T and the electric field. It is a graph which shows the relationship between the ratio of the thickness Ta of the 1st resin layer with respect to the whole film thickness T, and the electric field increase rate of an air gap. It is sectional drawing which shows the insulated wire which concerns on the 2nd Example of this invention, (A) shows the case where a cross section is a round shape, (B) shows the case where a cross section is a square. It is a graph which shows the electric current characteristic in the high-temperature applied state in the case of the insulated wire which coat | covered the resin of polyphenylene sulfide (PPS).

Explanation of symbols

T1, T2: Insulated wire 1: First resin layer 2: Second resin layer 3: Third resin layer 4: Conductor

Claims (11)

In an insulated wire formed by coating an outer periphery of a conductor with at least two layers of an insulating film,
A first resin layer having a relative dielectric constant ε1 coated on the outer periphery of the conductor;
A second resin layer having a relative dielectric constant ε2 coated on the outer periphery of the first resin layer,
At 150 ° C. or higher, ε1 / ε2> 1
An insulated wire characterized by that.   The insulated wire according to claim 1, wherein the relationship is ε1 / ε2> 1.1 at 150 ° C. or higher.   The thickness of the first resin layer is greater than 0% and 30% or less of the total thickness of the first resin layer and the second resin layer. The insulated wire as described in 1.   The thickness of the first resin layer is greater than 0% and not more than 20% of the total thickness of the first resin layer and the second resin layer. Insulated wires.   The first resin layer and the second resin layer are made of a material selected from an amorphous resin having a glass transition temperature of 150 ° C. or higher or a crystalline resin having a melting point of 150 ° C. or higher. The insulated wire according to any one of claims 1 to 4. A third resin layer having a relative dielectric constant ε3 coated on the outer periphery of the second resin layer;
At 150 ° C. or higher, there is a relationship of ε3 / ε2> 1.
The insulated wire according to any one of claims 1 to 5, wherein   The insulated wire according to claim 6, wherein the relation is ε3 / ε2> 1.1 at 150 ° C or higher.   The total thickness of the first resin layer and the third resin layer is more than 0% of the total thickness of the first resin layer, the second resin layer, and the third resin layer. The insulated wire according to claim 6 or 7, which is large and 30% or less.   The total thickness of the first resin layer and the third resin layer is more than 0% of the total thickness of the first resin layer, the second resin layer, and the third resin layer. The insulated wire according to claim 8, which is large and 20% or less.   10. The third resin layer is made of a material selected from an amorphous resin having a glass transition temperature of 150 ° C. or higher or a crystalline resin having a melting point of 150 ° C. or higher. The insulated wire according to any one of the items.   The deterioration prevention layer for preventing deterioration of the resin layer by the said conductor is formed between the said conductor and the said 1st resin layer, The any one of Claim 1 thru | or 10 characterized by the above-mentioned. The insulated wire as described in the item.

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