JP2017016956A - Insulated wire and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To coat every side of conductor wire including a pair of flat sides parallel to a periphery side with a resin insulating layer of enough thickness to get reliable insulating properties.SOLUTION: In a manufacturing method of insulated wire coating a periphery side of conductor wire with a resin insulating layer by putting the conductor wire including a pair of flat sides parallel to the periphery side through varnish for electropainting, the varnish contains resin for painting, water and water-soluble solvent which is good solvent for the resin for painting, and content of water in the vanish is 55-75 mass%.SELECTED DRAWING: None

Description

  The present invention relates to an insulated wire and a method for manufacturing the same.

  In the field of electric and electronic equipment, high performance, lightness and miniaturization, power saving, etc. are rapidly progressing. Along with this, further miniaturization of coils, noise filters, inductors, reactors and the like mounted on an electronic board is required. Therefore, in order to increase the area occupied by the conductor per cross-sectional area, a rectangular conductor wire having a flat cross-sectional shape has been put into practical use. Such a rectangular conducting wire is usually used as an insulated wire whose outer peripheral surface is covered with a resin insulating layer made of resin. And it is known that the coating of the outer peripheral surface of the flat conducting wire with the resin insulating layer is performed by electrodeposition coating. For example, Patent Document 1 discloses that a resin insulating layer covering the outer peripheral surface of a rectangular conductor wire is formed of a block copolymerized polyimide resin containing a siloxane bond in the main chain and having an anionic group in the molecule. It is disclosed.

JP 2005-174561 A

  In the case where the outer peripheral surface of the flat conducting wire is coated with a resin insulating layer by electrodeposition coating, in order to obtain a reliable insulating property, it is necessary that the resin insulating layer on any surface has a sufficient thickness.

  An object of the present invention is to cover any surface of a conducting wire including a pair of flat surfaces parallel to the outer peripheral surface with a resin insulating layer having a sufficient thickness in order to obtain reliable insulation.

  The method for producing an insulated wire according to the present invention is a method for producing an insulated wire in which a conductive wire including a pair of flat surfaces parallel to the outer peripheral surface is electrodeposited through a varnish to coat the outer peripheral surface of the conductive wire with a resin insulating layer. And the said varnish contains the resin for coating, water, and the water-soluble solvent which is a good solvent with respect to the said resin for coating, The content of the water in the said varnish is 55-75 mass%.

  The insulated wire of the present invention is an insulated wire comprising a flat conducting wire having a flat cross-sectional shape and a resin insulating layer covering an outer peripheral surface of the flat conducting wire, wherein the resin insulating layer is a flat conductor of the flat conducting wire. The thickness of the portion corresponding to the short side in a simple cross-sectional shape is larger than the thickness of the portion corresponding to the long side.

  According to the present invention, the varnish used for electrodeposition coating contains a coating resin, water, and a water-soluble solvent that is a good solvent for the coating resin, and the water content in the varnish is 55 to 55. By being 75 mass%, any surface of the conducting wire including a pair of flat surfaces parallel to the outer peripheral surface can be covered with a resin insulating layer having a sufficient thickness to obtain reliable insulation.

It is a figure which shows the process order of the manufacturing method of the insulated wire which concerns on embodiment. It is a perspective view of the flat conducting wire concerning an embodiment. It is a perspective view of the other flat conducting wire which concerns on embodiment. It is a perspective view of the insulated wire which concerns on embodiment. It is a perspective view of the other insulated wire which concerns on embodiment. It is explanatory drawing which shows the measuring method of a coil dielectric breakdown voltage value.

  Hereinafter, embodiments will be described in detail.

  As shown in FIG. 1, the method for manufacturing an insulated wire according to the embodiment includes a wire drawing process, a cold working process, an annealing process, an oil removing process, and an electrodeposition coating process. In addition, these processes may perform each process by a batch type, and may perform all the processes by a continuous type. Furthermore, for example, a wire drawing process and a cold working process are performed by a continuous type. After performing, only an annealing process may be performed by a batch type, and it may carry out combining a batch type and a continuous type like the case where the oil removal process and electrodeposition coating process after that are performed by a continuous type.

<Wire drawing process>
In the wire drawing process, the rough drawn wire as a bus bar is reduced in diameter and drawn into a round wire having a circular cross section. For the rough drawn wire, for example, high purity copper having a purity of 4N or more is used. In general, the drawing process includes a process of passing a rough drawing wire through a drawing die. The outer diameter of the rough drawn wire is, for example, 8.0 mm, and the outer diameter of the round wire after drawing is, for example, 0.05 to 0.2 mm. Note that the wire drawing is usually performed in multiple stages. For example, first, a rough drawing wire having an outer diameter of 8.0 mm is drawn so that the outer diameter is 2.6 to 3.2 mm, and then 0.6 to The wire is drawn to 0.8 mm, and further drawn to 0.05 to 0.2 mm.

<Cold working process>
In the cold working step, the round wire drawn in the drawing step is cold worked into a conductive wire including a pair of flat surfaces parallel to the outer peripheral surface. Examples of cold working include rolling that passes a round wire between rollers of a rolling mill, processing that passes a round wire through a die, and the like. The conducting wire obtained by the cold working may be a rectangular conducting wire 11 having a flat cross-sectional shape in which the upper and lower surfaces and both side surfaces are formed flat as shown in FIG. 2A. Such a rectangular conducting wire 11 can be obtained, for example, by rolling a round wire in each of the thickness direction and the width direction. Moreover, the conducting wire obtained by the cold working is a flat conducting wire 11 having a flat cross-sectional shape formed in a curved surface in which the upper and lower surfaces are formed flat as shown in FIG. Also good. Such a rectangular conducting wire 11 can be obtained, for example, by rolling a round wire only in the thickness direction. These flat conductive wires 11 have, for example, a thickness of 0.01 to 1 mm and a width of 0.2 to 4.0 mm, and a ratio of width to thickness (width / thickness) of 1/1 to 25/1. It is. The conductive wire obtained by cold working is not particularly limited as long as it includes a pair of flat surfaces parallel to the outer peripheral surface. For example, the cross-sectional shapes having the same dimensions in the thickness direction and the width direction are used. It may be square.

<Annealing process>
In the annealing process, physical properties such as crystal grain size and 0.2% proof stress of the metal forming the conducting wire are adjusted by heat treatment.

  The annealing process is preferably performed batchwise from the viewpoint of uniformizing the characteristics in the length direction. In that case, a predetermined temperature increase is performed after the bobbin around which the wire after the cold working process is wound is put into a heat treatment furnace. It is preferable to increase the temperature in the furnace to a predetermined holding temperature at a speed, hold the predetermined holding time at the holding temperature, and then lower the temperature in the furnace at a predetermined temperature drop rate. At this time, the temperature rising rate is, for example, 20 to 2000 ° C./h. The holding temperature (annealing temperature) is, for example, 150 to 1000 ° C. The holding time (annealing time) is, for example, 1 second to 100 hours. The temperature drop rate is, for example, 10 to 2000 ° C./h. Moreover, when performing an annealing process by a continuous type, Preferably heat treatment conditions are annealing temperature 500-900 degreeC, annealing time 1-60 seconds, More preferably, annealing temperature 600-800 degreeC and annealing time 1-10 seconds. The annealing step is preferably performed in an inert gas atmosphere such as nitrogen gas.

<Oil removal process>
In the oil removal step, the oil attached to the surface of the conducting wire is washed away. This cleaning can be performed, for example, by immersing the conducting wire in a cleaning solution and pulling it up, and then spraying an inert gas such as nitrogen gas to scatter the cleaning solution adhering to the conducting wire.

  Here, examples of the cleaning liquid include water (warm water), an organic solvent, and the like. When the cleaning liquid is water, the water temperature is, for example, 10 to 60 ° C. The cleaning liquid may contain a detergent.

<Electrodeposition painting process>
In the electrodeposition coating process, an electrodeposition coating is applied to the surface of the conductive wire to provide an insulating coating layer of an electrodeposition coating. Specifically, the conductive wire is continuously passed through the varnish and a voltage is applied to the varnish by using the conductive wire as one electrode, and an insulating film is attached to the surface of the conductive wire, and then it is passed through a baking furnace to the conductive wire. An insulating coating layer is formed by baking the attached insulating coating.

  Here, the varnish used for electrodeposition coating includes a coating resin, water, and a water-soluble solvent. The varnish may be either an anionic type or a cationic type. The varnish may be either an aqueous solution in which an aqueous coating resin is dissolved in water or a dispersion in which coating resin particles are dispersed in water.

  Examples of the coating resin include a polyimide resin having a polyimide resin skeleton, a polyamide imide resin having a polyamide imide resin as a skeleton, a polyester imide resin having a polyester imide resin as a skeleton, and an acrylic resin having an acrylic resin as a skeleton. Examples thereof include resins, epoxy resins having an epoxy resin as a skeleton, epoxy acrylate resins having an epoxy acrylate resin as a skeleton, polyurethane resins having a polyurethane resin as a skeleton, polyester resins having a polyester resin as a skeleton, and the like. Of these, it is preferable to use one or more of these as the coating resin. From the viewpoint of increasing the heat resistance and hardness of the insulating coating layer, it is more preferable to use a polyimide resin and / or a polyamideimide resin as the coating resin. The density | concentration of solid content containing the resin for coating in a varnish becomes like this. Preferably it is 1 mass% or more, More preferably, it is 5 mass% or more, Preferably it is 15 mass% or less, More preferably, it is 10 mass% or less.

  The varnish contains water, but its content is 55 to 75% by mass. As described above, when the water content in the varnish is 55 to 75% by mass, any surface of the conducting wire including a pair of flat surfaces parallel to the outer peripheral surface has a sufficient thickness to obtain reliable insulation. It can be coated with a resin insulating layer. From this viewpoint, the content of water in the varnish is preferably 60% by mass or more, and preferably 70% by mass or less.

  The water-soluble solvent needs to be a good solvent for the coating resin. Here, the “water-soluble solvent” refers to a solvent that has an affinity for water and becomes a uniform single phase by mixing with water without phase separation. The “good solvent for the coating resin” refers to a solvent having high solubility in the coating resin, specifically, a solvent in which the amount of the coating resin dissolved in 1 kg of solvent at 25 ° C. is 100 g or more. Examples of such a water-soluble solvent include N-methyl-2-pyrrolidone (NMP) in the case where the coating resin is a polyimide resin or a polyamideimide resin. Such a solvent may contain either a single species or a plurality of species. The content of the water-soluble solvent in the varnish is preferably 24% by mass or more, more preferably 26% by mass, from the viewpoint of film forming properties of the insulating coating layer and the need to swell the insulating coating layer after electrodeposition coating. In addition, from the viewpoint of obtaining a resin insulating layer having a sufficient thickness for obtaining reliable insulation on any surface, it is preferably 32% by mass or less, more preferably 30% by mass or less.

  In addition, the varnish may contain a neutralizing agent, a coloring agent, and the like.

  Although the viscosity of a varnish is measured with a B-type viscometer, it is 1-100 mPa * s, for example. The pH of the varnish is measured with a pH meter, and is, for example, 7-9.

  The voltage application to the varnish may be performed by a constant current method or a constant voltage method. The applied voltage is, for example, 40 to 100V.

  The liquid temperature of a varnish is 10-30 degreeC, for example. The immersion time of the conducting wire in the varnish is, for example, 5 to 120 seconds. This immersion time can be adjusted by setting the traveling speed of the conducting wire.

  In the electrodeposition coating process, the tank containing the varnish may be housed in a compartment, and the conductor may be immersed in the varnish in a low vacuum atmosphere (100 Pa or more) or a nitrogen gas atmosphere.

  The baking temperature, that is, the furnace temperature of the baking furnace is, for example, 100 to 600 ° C. The baking process time is, for example, 300 to 1800 seconds. The baking process time can be adjusted by setting the traveling speed of the conducting wire.

  The baking process may be performed in one stage depending on a single baking process temperature, or may be performed in multiple stages at different baking process temperatures. In the latter case, for example, the baking process temperature in each stage is fixed to 100 to 600 seconds, the baking process temperature is set to 150 to 180 ° C. in the first stage, and the baking process temperature is set to be higher than that in the first stage in the second stage. A higher baking temperature is set to 180 to 210 ° C., and a third baking temperature is set to a higher baking temperature than the second temperature to 210 to 240 ° C., and finally the baking temperature is cooled to room temperature. Thus, foaming in the insulating coating layer can be suppressed by sequentially setting the baking temperature higher.

  According to the method for manufacturing an insulated wire according to the embodiment as described above, the varnish used for electrodeposition coating includes a coating resin, water, and a water-soluble solvent that is a good solvent for the coating resin, And as above-mentioned, since content of the water in a varnish is 55-75 mass%, it is enough in order to acquire reliable insulation of any surface in the conducting wire containing a pair of flat surface parallel to an outer peripheral surface. It can be covered with a thick resin insulation layer. The thickness of the resin insulating layer is preferably 1.5 μm or more, more preferably 3 μm or more, and preferably 30 μm or less, more preferably 25 μm or less.

  In particular, in the case where the conductor is a flat conducting wire 11 having a flat cross-sectional shape as shown in FIGS. 2A and 2B, conventionally, the resin insulating layer formed by electrodeposition coating corresponds to the short side in the flat cross-sectional shape. Since the thickness of the portion corresponding to the short side is extremely thin, in some applications where the portion corresponding to the short side is subjected to high pressure, sufficient insulation may not be obtained. However, according to the method for manufacturing an insulated wire according to the embodiment, when the conductor is a flat conducting wire 11 having a flat cross-sectional shape as shown in FIGS. 2A and 2B, the insulated wire obtained as shown in FIGS. 10, in the resin insulating layer 12, both the short-side corresponding part 12 a corresponding to the short side and the long-side corresponding part 12 b corresponding to the long side in the flat cross-sectional shape of the flat conducting wire 11 are required to obtain reliable insulation. The thickness of the short side corresponding part 12a is larger than the thickness of the long side corresponding part 12b. Thus, when the short side corresponding part 12a is formed thicker than the long side corresponding part 12b, even if the short side corresponding part 12a is subjected to a high pressure, it is surely sufficient in insulation. Can be obtained. The ratio of the thickness of the short side corresponding part 12a to the long side corresponding part 12b is preferably greater than 1.0, more preferably 1.2 or more, and preferably 1.4 or less, more preferably 1 .3 or less. In addition, the thickness of the short side corresponding | compatible part 12a and the long side corresponding | compatible part 12b is the thickness of each thinnest part.

(Insulated wire)
The insulated wires of Examples 1 to 7 and Comparative Examples 1 and 2 below were produced. The composition of the varnish used in each is shown in Table 1.

<Example 1>
Including 3.0% by weight of solid content including polyimide resin as a coating resin, 68.6% by weight of water, 4.4% by weight of methoxypropanol, 24.0% by weight of NMP, and 0.03% by weight of neutralizing agent A varnish was prepared.

  High-purity copper flat conductors (thickness 0.025 mm and width 0.25 mm) having a flat rectangular shape with flat top and bottom surfaces and both side faces are electrodeposited through the varnish and flattened. An insulated wire was produced by coating the outer peripheral surface of the conducting wire with an insulating coating layer. This was designated Example 1.

<Example 2>
An insulated wire was produced under the same conditions as in Example 1 except that a varnish having a water content of 64.6% by mass and an NMP content of 28.0% by mass was used. This was designated Example 2.

<Example 3>
An insulated wire was produced under the same conditions as in Example 1 except that a varnish having a water content of 60.6% by mass and an NMP content of 32.0% by mass was used. This was designated as Example 3.

<Example 4>
Except for using a varnish containing 8.0% by mass of a polyimide resin as a coating resin, 61.3% by mass of water, 4.2% by mass of methoxypropanol, and 26.5% by mass of NMP. An insulated wire was produced under the same conditions as in Example 1. This was designated Example 4.

<Example 5>
Implemented except that a varnish containing 1.0% by mass of a polyimide resin as a coating resin, 65.9% by mass of water, 4.5% by mass of methoxypropanol, and 28.6% by mass of NMP was used. An insulated wire was produced under the same conditions as in Example 1. This was designated as Example 5.

<Example 6>
The same conditions as in Example 1 except that a varnish with a water content of 60.6% by mass, a methoxypropanol content of 8.4% by mass, and an NMP content of 28.0% by mass was used. Insulated wires were produced. This was designated Example 6.

<Example 7>
An insulated wire was produced under the same conditions as in Example 1 except that a varnish with a water content of 72.6% by mass and an NMP content of 20.0% by mass was used. This was designated as Example 7.

<Comparative Example 1>
An insulated wire was produced under the same conditions as in Example 1 except that a varnish having a water content of 52.6% by mass and an NMP content of 40.0% by mass was used. This was designated as Comparative Example 1.

<Comparative example 2>
An insulated wire was produced under the same conditions as in Example 1 except that a varnish having a water content of 47.6% by mass and an NMP content of 45.0% by mass was used. This was designated as Comparative Example 2.

<Reference example>
A varnish with a water content of 77.6% by mass and an NMP content of 15.0% by mass was used, but no film could be formed by electrodeposition coating.

(Test method)
<Thickness of resin insulation layer>
A section of the insulated wire produced in each of Examples 1 to 7 and Comparative Examples 1 and 2 was observed with an enlarged microscope, and a pair of upper and lower long sides corresponding to the resin insulating layer covering the outer peripheral surface of the flat conducting wire The thickness of each thinnest part was measured and averaged. Similarly, the thicknesses of the thinnest portions of the pair of short sides on both sides in the resin insulating layer were measured and averaged. Then, the ratio of the average thickness of the short side corresponding portion to the average thickness of the long side corresponding portion (average thickness of the short side corresponding portion / average thickness of the long side corresponding portion) is calculated. did.

<Dielectric breakdown voltage value>
About the insulated wire produced in each of Examples 1 to 7 and Comparative Examples 1 and 2, when the resin insulation layer breaks based on “JIS C3216-5: 2011 JA.4.2c) metal foil method” The dielectric breakdown voltage value, which is a voltage, was measured. Then, the trial was performed 10 times, and the case where the average value was 800 V or more was evaluated as A, the case where it was 400 V or more and less than 800 V, B, and the case where it was less than 400 V was evaluated as C.

<Coil breakdown voltage value>
About the insulated wire produced in each of Examples 1-7 and Comparative Examples 1-2, it coiled and produced the test piece.

  As shown in FIG. 4, a coil-shaped test piece was placed on a conductor placed on a hot plate, and a weight of 100 g was placed thereon via an insulating plate. Then, a voltage is applied between the flat conductor of the insulated conductor of the test piece and the conductor, and the voltage is gradually increased to reduce the resin insulating layer, in particular, the short side corresponding portion of the resin insulating layer. A certain coil breakdown voltage value was measured. The pressurizing conditions were in accordance with “JIS C3216-5: 2011 JA.4.2c) metal foil method”.

  First, the measurement was performed without heating with a hot plate. Then, the trial was performed 15 times, and the case where the minimum value was 800 V or higher was evaluated as A, the case where 400 V or higher and lower than 800 V was evaluated as B, and the case where it was lower than 400 V was evaluated as C.

  Next, the hot plate was heated to 250 ° C., a weight was placed on the test piece via an insulating plate and held for 2 minutes, and measurement was performed. Then, the trial was performed 15 times, and the case where the minimum value was 500 V or more was evaluated as A, the case where 300 V or more and less than 500 V was evaluated as B, and the case where it was less than 300 V was evaluated as C.

(Test evaluation results)
The test results are shown in Table 1.

  According to this, in Examples 1 to 7 in which the content of water in the varnish is 55 to 75% by mass, the thickness of the short side corresponding part in the resin insulating layer is formed thicker than the thickness of the long side corresponding part, Therefore, it turns out that all have a high coil dielectric breakdown voltage value. In Example 7, although the dielectric breakdown voltage value is slightly low, it is considered that this is because the thickness of the long side corresponding portion is formed slightly thin because the water content in the varnish is relatively low.

  On the other hand, in Comparative Examples 1 and 2 in which the water content in the varnish is 52.6 mass% and 47.6 mass%, the thickness of the short side corresponding portion in the resin insulating layer is thinner than the thickness of the long side corresponding portion. Although the dielectric breakdown voltage level is high, the coil breakdown voltage value is very low.

  The present invention is useful in the technical field of an insulated wire and a manufacturing method thereof.

DESCRIPTION OF SYMBOLS 10 Insulated electric wire 11 Flat conductor 12 Resin insulating layer 12a Short side corresponding part 12b Long side corresponding part 21 Hot plate 22 Conductor 23 Insulating plate 24 Weight T Test piece

Claims (5)

A method for producing an insulated wire in which a conductive wire including a pair of flat surfaces parallel to the outer peripheral surface is passed through a varnish and electrodeposited to coat the outer peripheral surface of the conductive wire with a resin insulating layer,
The varnish includes a coating resin, water, and a water-soluble solvent that is a good solvent for the coating resin,
The manufacturing method of the insulated wire whose content of the water in the said varnish is 55-75 mass%. In the manufacturing method of the insulated wire described in Claim 1,
The manufacturing method of the insulated wire whose said conducting wire is a flat conducting wire which has a flat cross-sectional shape. In the manufacturing method of the insulated wire described in Claim 1 or 2,
The manufacturing method of the insulated wire whose content of the said water-soluble solvent in the said varnish is 24-32 mass%. In the manufacturing method of the insulated wire in any one of Claims 1 thru | or 3,
A method for producing an insulated wire, wherein the coating resin is a polyimide resin or a polyamideimide resin, and the water-soluble solvent is N-methyl-2-pyrrolidone. An insulated wire comprising a flat conducting wire having a flat cross-sectional shape, and a resin insulating layer covering an outer peripheral surface of the flat conducting wire,
The resin insulation layer is an insulated wire in which the thickness of the portion corresponding to the short side in the flat cross-sectional shape of the flat wire is thicker than the thickness of the portion corresponding to the long side.

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