JP2009129566A - Insulated electric wire and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insulated electric wire, along with its manufacturing method, which is excellent in voltage-resistance characteristics without increasing the thickness of an insulation film. <P>SOLUTION: An insulation paint 2 whose viscosity at 30°C is 0.005-0.05 Pa s is applied on the surface of a conductor 10 and baking is performed repeatedly. This operation is repeated to form an insulation film whose thickness is 3-15 μm. The insulated electric wire includes a conductor whose diameter is 0.035-0.15 mm and the insulation film whose thickness is 3-6.5 μm to cover the conductor. The insulation film contains polyurethane or polyester imide, and the insulation film breakdown voltage measured based on JIS-C3003 is 340 V or higher per film thickness of 0.001 mm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an insulated wire and a method for manufacturing the same. More specifically, the present invention relates to an insulated wire excellent in withstand voltage characteristics without increasing the thickness of the insulating coating and a method for manufacturing the same.

  In general, an insulated wire is manufactured by applying an insulating paint to the surface of a conductor and baking it at a predetermined temperature to form an insulating film (see, for example, Patent Document 1).

  When the insulated wire is used for an application where a high voltage is applied, for example, as an ignition coil wire for an automobile, the insulation film is required to have a withstand voltage characteristic. Since the withstand voltage characteristic of the insulating film improves in proportion to the film thickness, the withstand voltage characteristic is improved by increasing the film thickness of the insulating film.

JP 2007-149562 A

  However, increasing the coating thickness of the insulating coating inevitably increases the outer diameter of the insulated wire, resulting in an increase in the dimensions of the coil manufactured using this insulated wire. Development of an insulated wire excellent in insulating properties even if it is small is desired.

  This invention is made | formed in view of such a situation, and makes it a subject to provide the manufacturing method of the insulated wire excellent in the withstand voltage characteristic, without enlarging the film thickness of an insulating film. Moreover, this invention makes it a subject to provide the insulated wire excellent in the withstand voltage characteristic, even if the film thickness of the insulating film is not large.

  The method for producing an insulated wire according to the present invention is a method for producing an insulated wire having a conductor and an insulating film covering the conductor, and the surface of the conductor has a viscosity at 30 ° C. of 0.005 to 0.05 Pa · s. After applying a certain insulating paint, an operation of baking is repeated to form an insulating film having a film thickness of 3 to 15 μm. According to this manufacturing method, the occurrence of pinholes in the insulating film can be reduced by applying and baking an insulating paint having a lower viscosity than in the past, and the film thickness of the insulating film can be reduced. Even if it is not enlarged, an insulated wire excellent in withstand voltage characteristics can be obtained.

  According to the method for manufacturing an insulated wire of the present invention, an insulated wire excellent in insulation can be obtained without increasing the thickness of the insulation film even if the diameter of the conductor is 0.035 to 0.2 mm. Can do.

  According to the method for producing an insulated wire of the present invention, by using an insulating paint containing polyurethane or polyesterimide, an insulated wire having excellent withstand voltage characteristics and excellent solderability can be obtained.

  The insulated wire of the present invention is an insulated wire having a conductor having a diameter of 0.035 to 0.15 mm and an insulating film having a coating thickness of 3 to 6.5 μm, and covering the conductor, and the insulating film is made of polyurethane. Alternatively, the dielectric breakdown voltage of the insulating film containing polyesterimide and measured according to JIS C3003 is 340 V or more per 0.001 mm of the film thickness. The insulated wire of the present invention is excellent in withstand voltage characteristics even though the thickness of the insulating coating is as small as 3 to 6.5 μm, so that the outer diameter of the insulated wire can be reduced.

  According to the method for manufacturing an insulated wire of the present invention, an insulated wire having excellent withstand voltage characteristics can be obtained without increasing the thickness of the insulating coating. Moreover, the insulated wire of this invention is excellent in the withstand voltage characteristic, even if the film thickness of the insulating film is not large.

  The method for producing an insulated wire according to the present invention is a method for producing an insulated wire having a conductor and an insulating film formed on the conductor, and the viscosity of the conductor at 30 ° C. is 0.005 to 0.05 Pa · After applying the insulating paint as s, the operation of baking is repeated to form an insulating film having a film thickness of 3 to 15 μm. Since the method for manufacturing an insulated wire according to the present invention has the above-described characteristics, an insulated wire having excellent withstand voltage characteristics can be manufactured without increasing the thickness of the insulating coating. Therefore, the insulated wire of this invention can be used conveniently for the use to which a high voltage is applied like the electric wire for ignition coils of a motor vehicle, for example.

  There is no limitation in particular as a conductor, For example, a copper wire etc. are mentioned. The diameter of the conductor (conductor diameter) is preferably 0.035 mm or more, more preferably 0.04 mm or more, from the viewpoint of securing the strength of the insulated wire. Moreover, from a viewpoint of the coating device to be used, it is preferably 0.1 mm or less, more preferably 0.06 mm or less. Thus, in this invention, the conductor which has a wide diameter from a thin line to a thick line can be used. In particular, even a conductor having a diameter of 0.035 to 0.15 mm, preferably 0.04 to 0.1 mm, which has been conventionally considered difficult to impart withstand voltage characteristics, is excellent. Withstand voltage characteristics can be imparted.

  In the method for producing an insulated wire of the present invention, first, an insulating paint having a viscosity of 0.005 to 0.05 Pa · s at 30 ° C. is applied to the surface of the conductor. The present invention has one major feature in that an insulating paint having a viscosity at 30 ° C. within a specific range is used as the insulating paint. In the present invention, the operation of adjusting the viscosity of the insulating paint at 30 ° C. to be within a specific range and repeating the application and baking so that the insulating paint has a predetermined film thickness is employed. Compared with the case where the same film thickness is formed using an insulating paint having a viscosity higher than the viscosity, the coating can be applied uniformly. As a result, the generation of pinholes is reduced, and an insulating film having excellent withstand voltage characteristics can be formed.

  The viscosity of the insulating paint is defined by the viscosity at 30 ° C. Since the viscosity of the insulating paint usually varies depending on the temperature of the paint, when the insulating paint is applied at a temperature higher than 30 ° C., the viscosity at the time of application becomes lower than the viscosity at 30 ° C.

  The temperature of the insulating paint when applying the insulating paint to the conductor varies depending on the equipment used, but as it increases, the solvent contained in the insulating paint volatilizes and the viscosity of the insulating paint changes during application. Since there exists a tendency which becomes easy, it is preferable normally that it is normal temperature-50 degreeC.

  The viscosity of the insulating paint may be adjusted, for example, by adjusting the solid content of the insulating paint, or may be adjusted by adjusting the temperature of the insulating paint when the insulating paint is applied to the conductor.

  The viscosity at 30 ° C. of the insulating coating is 0.005 Pa · s or more, preferably 0.01 Pa · s or more from the viewpoint of uniformly applying to the conductor, and 0.05 Pa · s from the viewpoint of improving productivity. Hereinafter, it is preferably 0.04 Pa · s or less. The viscosity of the insulating paint is a value when the insulating paint is measured at 30 ° C. using a Brookfield viscometer (rotor No. 2). Therefore, the viscosity of the insulating coating when applied to the conductor is the above viscosity if the temperature at the time of application is 30 ° C., and lower than the above viscosity if the temperature at the time of application is higher than 30 ° C.

Examples of the insulating paint include an insulating paint obtained by dissolving an insulating resin in an organic solvent.
Examples of the resin include polyesterimide, polyamideimide, polyimide, polyvinyl chloride, polyethylene, polyamide, polyester, and polyurethane. Among these, polyurethane and polyesterimide are preferable from the viewpoint of enhancing the withstand voltage characteristics of the insulated wire of the present invention and facilitating soldering.

  Polyurethane includes polyester-based polyurethane and polyether-based polyurethane. The polyester-based polyurethane can be obtained, for example, by a polyaddition reaction of adipate obtained by polycondensation of adipic acid and a polyhydric alcohol and diisocyanate. The polyether-based polyurethane can be obtained, for example, by reacting a difunctional polyether such as poly (oxypropylene) glycol (PPG) or poly (oxytetramethylene) glycol (PTMG) with a diisocyanate.

  Polyesterimide can be obtained, for example, by reacting imidodicarboxylic acid, which is a reaction product of tricarboxylic acid anhydride and diamine, with polyhydric alcohol.

  Examples of the organic solvent include polar organics such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, tetramethylurea, hexaethyl phosphate triamide, and γ-butyrolactone. Solvents, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; esters such as methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate; diethyl ether, ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, ethylene glycol Ethers such as monobutyl ether (butyl cellosolve), diethylene glycol dimethyl ether, tetrahydrofuran; hexane, heptane, benzene, toluene, xylene Hydrocarbon compounds such as dichloromethane and chlorobenzene; phenols such as cresol and chlorophenol; tertiary amines such as pyridine and the like. These organic solvents may be used alone or in combination of two kinds. The above can be mixed and used. The amount of the organic solvent is preferably adjusted so that the insulating paint has a desired viscosity when applied to the surface of the conductor.

  When applying the insulating paint to the conductor, for example, a commonly used method such as a felt drawing method or a die method can be employed.

  Since the coating amount of the insulating paint per application varies depending on the type and viscosity of the insulating paint, it cannot be determined unconditionally. Since the insulating paint used in the present invention has a predetermined viscosity, a thin film of the insulating paint is usually formed when the insulating paint is applied to the conductor. From the viewpoint of forming a uniform insulating film on the conductor, an insulating paint is applied to the entire surface of the conductor.

  After the insulating paint is applied to the conductor, baking is performed. Although the baking temperature at the time of baking varies depending on the type of insulating paint, it cannot be determined unconditionally. However, from the viewpoint of improving the withstand voltage characteristics, it is usually preferably 300 to 450 ° C.

  In the present invention, the application of the insulating paint to the conductor and the baking thereof are repeated, and the number of repetitions (hereinafter referred to as the number of times of application) is adjusted so as to be a desired film thickness of the insulating film. Accordingly, the number of times of application varies depending on application conditions and the like, and cannot be determined unconditionally, but is usually about 7 to 30 times.

  By repeatedly applying the insulating paint to the conductor and baking it as described above, an insulating film is formed on the conductor. The thickness of the formed insulating film varies depending on the use of the insulated wire of the present invention and cannot be determined unconditionally, but is usually 3 μm or more, preferably 5 μm or more from the viewpoint of protecting the conductor. From the viewpoint of reducing the size of the coil manufactured using the insulated wire, it is 15 μm or less, preferably 10 μm or less. When the conductor is a thin wire having a diameter of 0.035 to 0.15 mm, the thickness of the insulating film is 3 μm or more, preferably 4 μm or more from the viewpoint of protecting the conductor. From the viewpoint of preventing the diameter of the insulated wire from becoming too large, it is 6.5 μm or less, preferably 6 μm or less.

  The insulated wire of the present invention thus obtained has excellent withstand voltage characteristics even if the thickness of the insulation film is not large, and therefore, a high voltage is applied like a wire for an ignition coil of an automobile. Can be suitably used.

  Next, the present invention will be described in more detail based on examples. However, the present invention is not limited to such examples.

Example 1
The insulated wire was produced using the insulated wire manufacturing apparatus shown in FIG. The insulated wire manufacturing apparatus 1 is a horizontal apparatus that employs a felt drawing method to apply a certain amount of insulating paint. The insulated wire manufacturing apparatus 1 includes a coater roll 3, and includes an insulating paint coating unit 5 including a paint tank 4 filled with an insulating paint 2, an insulating paint squeezing felt unit 6, and a baking furnace 7. ing.

  The coater roll 3 has a diameter of 70 mm and rotates in the direction of arrow A. The insulating paint squeezing felt part 6 has a felt 8 thickness of 10 mm, a conductor passing width of 20 mm, and a weight plate 9 weighing 100 g. The baking furnace 7 is an electrothermal type in which the interior of the furnace is heated by an electric heater, and temperature management is possible for each zone of the inlet, the center, and the outlet.

  As the insulating paint 2, polyurethane [manufactured by Dainichi Seika Kogyo Co., Ltd., product name: FS-144] (main component: polyester polyurethane, nonvolatile content: 27% by weight, viscosity: 0.06 Pa · s [30 ° C., Brookfield viscometer (rotor No. 2)], solvent: cresol / xylene mixed at a weight ratio of 50/50), cresol and xylene at a weight ratio of 77.8: 11.1: 11.1 What was mixed with was used. The non-volatile content (resin concentration) of the insulating paint 2 (liquid temperature: 30 ° C.) in the paint tank 4 is 21% by weight, and the viscosity at 30 ° C. is 0.02 Pa · s [Brookfield viscometer (rotor No. .2)].

  A copper conductor 10 having a diameter of about 0.048 mm is run in a white arrow direction at a linear speed of 210 m / min, and an insulating paint 2 at 30 ° C. is applied to the surface of the conductor 10 by a coater roll 3 rotating in the arrow A direction. did. Then, it baked by passing the inside of the baking furnace 7 through the insulating paint squeezing felt part 6. As shown in Table 1, the temperature in the baking furnace 7 (baking temperature) is set so as to increase as it proceeds from the inlet to the outlet. By repeating this coating and baking operation 9 times, an insulated wire having the dimensions shown in Table 1 (finished outer diameter, conductor diameter and film thickness) was obtained.

  Here, the dimension was measured according to JIS C3003 “5.2a round wire”. Specifically, the finished outer diameter is about 15 cm in length, and the diameter is measured with three micrometers at approximately the same angle on the same plane perpendicular to the conductor axis, and the average value of these measured values. expressed.

The conductor diameter was measured by the same method as the above-mentioned “finished outer diameter” after burning the film of the place where the finished outer diameter was measured with flame and immersing it in alcohol, and expressing the average value.
The film thickness was determined by calculating the difference between the finished outer diameter and the conductor diameter and dividing this difference by 2.

  As physical properties of the obtained insulated wire, appearance, pinhole, 3% pinhole, flexibility, adhesion, elongation and withstand voltage characteristics (dielectric breakdown voltage, dielectric breakdown voltage per 0.001 mm of film thickness and VT characteristics) ) Was evaluated based on the following method. The results are shown in Table 1.

(1) Appearance The presence or absence of gloss, the presence or absence of bubbles, and the presence or absence of scratches are visually observed using a magnifying glass. ".

(2) Pinhole Measured according to JIS C3003 “6c pinhole method”. More specifically, an insulated wire having a length of about 5 m was immersed as a test piece in 0.2% saline in which a 3% alcohol solution of phenolphthalein was dropped. And salt water was made into the positive electrode, the insulated wire was made into the negative electrode, DC voltage of 12V was applied for 1 minute, and the number of the generated pinholes was counted.

(3) Pinhole after 3% elongation After extending the length of an insulated wire having a length of about 1 m by 3%, the number of pinholes generated in the same manner as in (2) was counted.

(4) Flexibility Measured according to JIS C3003 “7.2.1a elongation”. More specifically, three insulated wires having a length of about 35 cm are taken from the same winding frame, the distance between the marked lines is set to 250 mm for each, the length of the insulated wires is extended by 3%, and the conductor is applied to the insulating film. It was examined with a magnifying glass about 15 times whether or not cracks were visible. If there was no crack, it was judged as “good”, and if there was a crack, it was judged as “bad”.

(5) Adhesiveness Measured according to JIS C3003 “8.1a rapid elongation”. More specifically, an insulated wire with a distance between marked lines of 250 mm was rapidly extended until it was broken, and whether or not the broken insulated wire was cracked was examined with a magnifying glass. When the number of cracks was 0, it was determined as “good”, and when a crack occurred, it was determined as “bad”.

(6) Elongation rate at break The insulated wire with a distance of 250 mm between the marked lines was pulled at a pulling speed of 100 mm / min, and the length at break was measured with an autograph.
[Elongation at break (%)] = [(Length at break−250) ÷ 250] × 100
Based on.

(7) Dielectric strength characteristics (i) Dielectric breakdown voltage Measured according to JIS C3003 “Method from two 10.2b”. More specifically, three insulated wires having a length of about 50 cm are taken from the same reel, each of which is folded into two, and a portion having a length of about 12 cm is applied 50 times while applying a tension of 0.0294N. After twisting, the tension was removed, and the crease portion was removed to produce two insulated wires. An alternating voltage of 50 Hz or 60 Hz was applied between two conductors of these two insulated wires while increasing the voltage at 500 V / s, and the voltage (kV) when the insulating film was broken and short-circuited was measured. Table 1 shows the average value of the three insulated wires.

(Ii) Dielectric breakdown voltage per 0.001 mm of film thickness From the value of the film thickness obtained in the above “dimension” and the value of the dielectric breakdown voltage obtained in (i) above, the dielectric breakdown per 0.001 mm Voltage, formula:
[Dielectric breakdown voltage per coating thickness 0.001mm (V)]
= [Dielectric breakdown voltage (kV) / film thickness (mm) x 2]
Based on.

(Iii) VT characteristics The VT characteristics are characteristics indicating the relationship between the breakdown voltage and the breakdown time when an overvoltage is applied. Using the same two insulated wires as in the dielectric breakdown voltage test of (i) above, a voltage of 1.3 kV is continuously applied between the two conductors at a frequency of 1 kHz, and the insulation film is broken and short-circuited. Time (seconds) was measured. Three insulated wires were measured and the average value is shown in Table 1.

Example 2
In Example 1, an insulated wire was produced in the same manner as in Example 1 except that the number of times of applying the insulating paint was changed from 9 times to 12 times. The physical properties of the obtained insulated wires were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 3
In Example 1, the number of times of applying the insulating paint was changed from 9 to 15, and the temperature in the baking furnace (inlet / center / outlet) was 310 ° C and 320 ° C instead of 320 ° C, 330 ° C and 340 ° C, respectively. And the insulated wire was produced like Example 1 except having been 330 degreeC. The physical properties of the obtained insulated wires were examined in the same manner as in Example 1. The results are shown in Table 1.

Example 4
In Example 1, the number of times of applying the insulating paint was changed from 9 times to 18 times, and the temperature in the baking furnace (inlet / center / outlet) was 310 ° C. and 320 ° C. instead of 320 ° C., 330 ° C. and 340 ° C., respectively. And the insulated wire was produced like Example 1 except having been 330 degreeC. The physical properties of the obtained insulated wires were examined in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1
In Example 1, instead of the insulating paint having a viscosity of 0.02 Pa · s at the time of application (30 ° C.), the above polyurethane resin [nonvolatile content: 27 wt%, viscosity: 0.06 Pa · s (30 ° C., Brookfield viscometer (rotor No. 2))] was used as an insulating coating without dilution, and the temperature in the baking furnace (inlet / center / outlet) was 340 ° C instead of 320 ° C, 330 ° C and 340 ° C. An insulated wire was produced in the same manner as in Example 1 except that the temperature was 350 ° C. and 360 ° C. The physical properties of the obtained insulated wire were examined in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 2
In Example 1, instead of an insulating paint with a viscosity of 0.02 Pa · s at the time of application (30 ° C.), an insulating paint of 0.06 Pa · s was used, and the number of times of applying the insulating paint was changed from 9 times to 12 times. Insulated wire in the same manner as in Example 1 except that the temperature in the baking furnace (inlet / center / outlet) was changed to 330 ° C, 340 ° C and 350 ° C instead of 320 ° C, 330 ° C and 340 ° C, respectively. Was made. The physical properties of the obtained insulated wires were examined in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 3
In Example 1, instead of an insulating paint with a viscosity of 0.02 Pa · s at the time of application (30 ° C.), an insulating paint of 0.06 Pa · s was used, and the number of times of applying the insulating paint was changed from 9 to 15 times. An insulated wire was produced in the same manner as in Example 1 except that. The physical properties of the obtained insulated wires were examined in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 4
In Example 1, instead of an insulating paint having a viscosity of 0.02 Pa · s at the time of application (30 ° C.), an insulating paint having a viscosity of 0.06 Pa · s was used, and the number of times of applying the insulating paint was changed from 9 to 18 times. Insulated wire in the same manner as in Example 1 except that the temperature in the baking furnace (inlet / center / outlet) was 310 ° C, 320 ° C and 330 ° C instead of 320 ° C, 330 ° C and 340 ° C, respectively. Was made. The physical properties of the obtained insulated wires were examined in the same manner as in Example 1. The results are shown in Table 2.

  From the results shown in Table 1 and Table 2, the insulated wires obtained in each example were the insulated wires obtained in each comparative example using an insulating paint having a viscosity of 0.06 Pa · s when applied. In contrast to this, it can be seen that the dielectric breakdown voltage and the VT characteristics, particularly the VT characteristics, are excellent as the withstand voltage characteristics despite the same film thickness.

Example 5
In Example 1, by changing the coating temperature of the insulating paint from 30 ° C. to 40 ° C., the viscosity at the time of coating is changed from 0.02 Pa · s to 0.018 Pa · s, and the number of times of applying the insulating paint is 9 times. Example 1 except that the temperature in the baking furnace (inlet / center / outlet) was changed to 340 ° C, 350 ° C and 360 ° C instead of 270 ° C, 300 ° C and 330 ° C, respectively. An insulated wire was produced in the same manner as described above. In addition, the insulating paint temperature at the time of application | coating is 40 degreeC. The physical properties of the obtained insulated wire were examined in the same manner as in Example 1. The results are shown in Table 3.

Example 6
In Example 5, the coating temperature of the insulating paint was changed from 40 ° C. to 45 ° C., so that the viscosity at the time of coating was changed from 0.018 Pa · s to 0.014 Pa · s. Thus, an insulated wire was produced. The physical properties of the obtained insulated wire were examined in the same manner as in Example 1. The results are shown in Table 3.

  From the results shown in Table 3, even when an insulated wire was manufactured using an insulating paint whose viscosity was lowered by increasing the temperature of the insulating paint at the time of application, the insulated wire obtained in each comparative example It can also be seen that an insulated wire excellent in dielectric breakdown voltage and VT characteristics, particularly VT characteristics can be obtained as the withstand voltage characteristics.

  The embodiment disclosed above should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic perspective view of the manufacturing apparatus of the insulated wire used for manufacture of the insulated wire of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulated wire manufacturing apparatus 2 Insulating paint 3 Coater roll 4 Paint tank 5 Insulating paint application part 6 Insulating paint squeeze felt part 7 Baking furnace 10 Conductor

Claims (4)

  A method of manufacturing an insulated wire having a conductor and an insulating film covering the conductor, wherein an insulating paint having a viscosity of 0.005 to 0.05 Pa · s at 30 ° C. is applied to the surface of the conductor and then baked. A method for producing an insulated wire, comprising repeating the operation to form an insulating film having a film thickness of 3 to 15 μm.   The method for manufacturing an insulated wire according to claim 1, wherein the conductor has a diameter of 0.035 to 0.2 mm.   The manufacturing method of the insulated wire of Claim 1 or 2 in which an insulating coating material contains a polyurethane or polyesterimide. An insulated wire having a conductor having a diameter of 0.035 to 0.15 mm, and an insulating film covering the conductor and having a film thickness of 3 to 6.5 μm,
The insulating film contains polyurethane or polyesterimide,
An insulated wire characterized by having a dielectric breakdown voltage measured by JIS C3003 of 340 V or more per 0.001 mm of film thickness.

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