JPS6158929B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention removes deposits attached to a "conductor" (hereinafter referred to as "conductor") by "electrolytic cleaning by connecting the conductor to a cathode" (hereinafter referred to as "electrolytic cleaning"). This invention relates to a method for manufacturing an insulated wire by removing the insulated wire and then applying and baking an insulating paint. The surface of the conductor is coated with metal powder unique to the metal generated during the wire drawing and rolling processes, as well as lubricating oil, grease, scale generated during high-temperature processing, and other particles generated during room-temperature processing. Usually, there is a deteriorated layer, oxides generated during storage, or dust from the atmosphere attached.

For conductors used in insulated wires, since insulating paint is applied and baked multiple times on the conductor, it has been thought that it is not necessarily necessary to remove deposits from the conductor surface. However, it has been conventionally considered that deposits on conductors may deteriorate the characteristics of insulated wires. For this reason, various methods have been studied and implemented to remove the deposits on the conductor, but it is still impossible to completely remove the deposits from the conductor.
There are no insulated wires manufactured by applying and baking insulating paint.

One method for removing deposits on the conductor is to physically remove the deposits by pressing the conductor with felt or cloth. With this method, in just a few minutes, the felt or cloth becomes dirty with the deposits on the conductor, and the removal effect of squeezing the conductor with the felt or cloth disappears. Therefore, the deposits on the conductor cannot be continuously removed unless the felt or cloth is changed every few minutes. This kind of thing cannot be put into practical use, and the felt would have to be replaced at most once every few hours. For this reason, the current situation is that even if it is pressed down with a conductor such as felt or cloth, the deposits are not effectively removed. Further, when removing deposits by passing through an organic solvent, the cleaning effect is great while the organic solvent is new, but the cleaning effect decreases in a short period of time. For this reason, it cannot be said to be a preferable cleaning method for long objects such as insulated wires, since the degree of removal of deposits varies from part to part.

In addition, many solvents are highly flammable, and there are also safety and hygiene issues, and facilities such as local exhaust ventilation and general ventilation are required. Furthermore, although the method of using vibration energy through ultrasonic cleaning is effective, it does not completely remove firmly adhered deposits, oils, fats, grease, etc. Although this method is used, it tends to require large-scale equipment.

However, recently, there has been a growing demand for high-performance insulated wires with no defects in the insulation coating or conductor, and there has also been an increase in the demand for high-performance insulated wires with no defects in the insulation coating or conductor. As many insulated wires coated with insulating paint and baked on were manufactured, and the appearance of these insulated wires began to be evaluated using a microscope, the appearance of insulated wires, which had not been a problem in the past, began to be checked more rigorously. Furthermore, as a measure to conserve resources, solvent-free or high-concentration insulating paints are increasingly being used, and while they have the advantage of reducing the number of times of coating and baking, they also tend to cause the coating surface to become undulating or uneven. As a result, we were forced to settle for low-quality insulated wires, and there was a growing momentum to solve these problems. In addition, as there is an increasing demand for strict guarantees on the full length of long items such as insulated wires, the inventors of the present invention have conducted extensive research and have found that deposits on conductors and conductor discoloration can be prevented by electrolysis. It was confirmed that by completely removing the particles through cleaning, it was possible to provide an insulated wire that completely met the above requirements.

The present invention will be explained in detail below.

The present invention provides, by electrolytically cleaning the conductor,
The purpose is to remove deposits on the conductor and discolored parts of the conductor, but if the conductor diameter exceeds 0.10 mm, by using the present invention, the ripples of the insulating film that occur when the insulating paint is baked can be removed. This has the advantage of improving quality by eliminating particles caused by foaming of the paint, which was mainly caused by deposits. This is thought to be because the copper powder and lubricating oil adhering to the conductor were removed by this method, and as a result, the surface tension of the conductor became uniform. Furthermore, when the conductor diameter is as small as 0.10 mm or less, the use of the present invention has the advantage that appearance defects due to discoloration of the conductor are significantly reduced.

When applying and baking insulating paint after using conventional felt or cloth, organic solvents, or ultrasonic cleaning methods, the copper powder and lubricating oil may not be sufficiently removed, causing the insulating film to ripple or bubble. It was a lot. Based on past statistics, even when using polyester insulation paint, which is said to be easy to manufacture, the number of reels that were defective due to rippling and foaming of the insulation coating was 3% of the total number of reels. Ta. Also, for example,
When using Du-Pont's polyimide insulation paint Pyre-ML, which is said to be extremely prone to foaming, the number of defective reels due to foaming reaches approximately 10% of the total number of reels, so the baking furnace temperature must be extremely low. However, it had to be manufactured at a slower line speed. For that reason,
Productivity is approximately 50% lower than that of polyester insulated wire.
%, which was extremely low. However, when the conductor is cleaned according to the present invention, the copper powder and lubricating oil are completely removed, so the ripples and foaming of the insulation film are almost completely eliminated not only in polyester insulation paint but also in polyimide insulation paint, which is truly remarkable. It was effective, and not only quality but also productivity improved significantly. For thin conductors with a conductor diameter of 0.10 mm or less, especially insulated wires with a conductor diameter of 0.060 mm to 0.010 mm used in watches, the appearance of the finished product is checked using a microscope. The most problematic problem with such thin insulated wires was black spot defects caused by deposits on the conductor. This black spot defect can be caused by not removing the deposits on the conductor.
It appears when insulating paint is applied and baked.
Efforts have therefore been made to remove the deposits on conductors, but to date no complete solution has been found. However, it has been found that when the electrolytic cleaning method is applied to such thin conductors, an insulated wire with no black spots and a good appearance can be obtained. Conventionally, before applying insulating paint to the conductor, organic solvent cleaning or ultrasonic cleaning has been performed to remove deposits, but the number of reels with black spots has increased to about 30% of all reels. However, by using the present invention, the number of reels with black spots is reduced to about 2% of the total number of reels.
It has now become possible to reduce it to . Further, the present invention showed remarkable effects when a wire having a conductor diameter of 0.5 mm or more had an insulation coating thickness of 0.020 mm or less.

For insulated wires that have been coated and baked with insulating paint, when a thin insulating film is applied and baked on a conductor with a conductor diameter of 0.5 mm or more, called thick and medium wire, by applying and baking it about 3 to 5 times, deposits on the conductor may be removed. The effect on the film is very large, and if there are any deposits on it,
Large and small ripples or large and small craters are formed in the coating everywhere, causing problems with the appearance of the insulated wire. The present invention was effective for an insulated wire having a thick medium conductor having such a thin film thickness. In other words, after electrolytically cleaning the conductor, applying and baking the insulating paint completely eliminated the ripples and large and small craters that had previously appeared in the film.

In addition, when a conductor is coated with a solvent-free insulating paint or a highly concentrated insulating paint, electrolytic cleaning of the conductor results in exactly the same appearance and electrical characteristics as when a general solvent-based insulating paint is used. Ta. Conventionally, when using solvent-free insulating paints or high-concentration insulating paints, it is possible to achieve the desired film thickness by reducing the number of applications, but the film often exhibits a defective appearance such as ripples or craters. There was a strong recognition that defects in the paint film would inevitably occur due to the use of paints. In addition, the properties such as dielectric breakdown voltage are not necessarily satisfactory when using these paints, and the dielectric breakdown voltage is about 70% to 80% compared to when using solvent-type insulation paints. However, this has also been thought to be caused by the use of these insulating paints.

However, when the conductor is cleaned using the present invention, copper powder and lubricating oil are completely removed, so even if a solvent-free insulation paint or a high-concentration insulation paint is used, there will be no ripples or craters in the coating. No film defects occurred, and the dielectric breakdown voltage value was not much better than that of the solvent type.

Another surprising feature of the present invention is that when conductors are cleaned by electrolytic cleaning, insulated wires that conventionally required a coating thickness of one type of structure can have sufficient electrical properties even with a coating thickness of two types of structure. In addition, it is a fact that an insulated wire that previously required a coating thickness of type 0 structure satisfies the electrical characteristics even with a coating thickness of type 1 structure. For example, conductor diameter 1.0mm
When manufacturing polyester insulated wires by coating and baking 40% polyester insulating paint on the conductor, if a conductor that is not electrolytically cleaned is used, if the film thickness is 0.050 mm, which is the type 0 structure, breakdown in saturated saline glycerin will occur. The average voltage was 7.5 KV, whereas when using an electrolytically cleaned conductor, the breakdown voltage value was almost the same at a film thickness of 0.040 mm, which is the type 1 structure. As can be seen from the above explanation, by electrolytically cleaning the conductor, deposits on the conductor are removed, the number of defects in the insulation film is reduced, the defective rate is reduced, the average dielectric breakdown voltage value is increased, and the quality is improved. I can see that the level is improving.

The reason that deposits on conductors are removed by electrolytic cleaning is that gas is generated by electrolysis of an electrolytic solution containing small amounts of carbonates, phosphates, caustic soda, common salt, hydrochloric acid, sulfuric acid, etc. that ionizes water well. This is because the deposits are physically separated from the conductor. When connecting the two electrodes when applying a DC voltage, generally when the metal to be treated is used as the cathode, hydrogen gas is generated and cathodic reduction occurs, giving the metal a shiny surface. On the other hand, when a metal is used as an anode, oxygen gas is generated and the metal is dissolved, so-called electrolytic polishing (electrolytic etching) occurs. Therefore, in order to remove strongly adhered deposits, first use the metal as an anode, dissolve the anode, and then use the metal as the cathode to perform cathodic reduction.The metal surface will be completely cleaned. come. However, in the case of copper wire, if the copper wire is used as an anode, it will undergo anodic oxidation, causing discoloration of the conductor, and even if it is then connected to the cathode, it will be difficult to obtain a shiny surface. If a copper wire is connected to the cathode and electrolytically cleaned, a copper wire with a metallic luster that is free of etching and deposits can be obtained.

When manufacturing insulated wires using a conductor whose surface has been removed by electrolytic cleaning, the conductor can be electrolytically cleaned before or after softening the conductor. But it's okay.

Furthermore, if the step of drawing the conductor and the step of applying and baking the insulating paint are performed in tandem, the conductor may be drawn after electrolytic cleaning, and then the insulating paint may be applied and baked.

In addition, the number of times electrolytic cleaning is performed in the present invention is
It is not necessary to perform electrolytic cleaning only once, but it is possible to perform electrolytic cleaning multiple times at positions deemed necessary. for example,
If the wire drawing process and baking process are done in tandem, the conductor should be electrolytically cleaned before wire drawing. In the next insulating paint baking step, before softening the conductor, electrolytic cleaning can be further performed, and then the insulating paint can be applied and baked. Furthermore, it is also possible to combine cleaning with an organic solvent, ultrasonic cleaning, etc., which have been conventionally used. In the present invention, the electrolytic cleaning solution includes:
Any electrolyte containing conductive ions in water can be used. However, those that are easily removed when removing the electrolytic cleaning solution adhered to the conductor, or
Considering the ease of processing used electrolytic cleaning solution,
carbonates, caustic soda, phosphates, silicates,
Alternatively, an aqueous solution in which a mixture of these is dissolved, or a dilute aqueous solution in which an acid such as hydrochloric acid, sulfuric acid, or nitric acid is diluted with water are effective. It is sufficient for the size of the electrolytic cleaning tank to be in the range of 10 cm to 100 cm in length, but this should be selected appropriately depending on the wire diameter, wire speed, and degree of adhesion of deposits to the conductor. I can do it. The current value also changes depending on the wire diameter and the length of the liquid tank, but when expressed in terms of current density, it is best to apply a current density of 0.5 to 20 mA/mm ² . The more firmly the deposit adheres to the conductor, the higher the current density needs to be applied.

The present invention further includes a technique of softening the conductor using a current applied to perform electrolytic cleaning. That is, if a current is applied to the conductor to the extent that the conductor is softened before entering the electrolytic cleaning tank, and then electrolytically cleaned immediately thereafter, there is an advantage that the conventional softening process of the conductor before applying the insulating paint is unnecessary. In the conventional softening process, in order to soften the conductor,
The conductor is softened by passing it through an electric or gas furnace, but the energy used to soften the conductor itself is only around 10% of the total energy. Used for heat dissipation. In addition, many softening furnaces use pipes, and the conductor is softened by passing it through the pipe, but wires may break in the pipe, so using a softening furnace is not recommended for manufacturing insulated wires. This reduced workability. Especially when the conductor diameter is
The effect of the present invention is remarkable because there are many disconnections in pipes for pipes with a narrow diameter of 0.1 mm or less. By using the present invention, this softening furnace is completely unnecessary, resulting in significant energy savings and production efficiency.

Next, the present invention will be explained with reference to the drawings.

FIG. 1 shows a method of manufacturing an insulated wire according to the present invention. The conductor 2 fed out from the supply reel 1 enters an electrolytic bath 3 containing an electrolytic cleaning solution and is electrolytically cleaned, then washed with water in a water washing bath 7, and then passed through a heat treatment furnace 8 for softening the conductor. ,
After applying the insulating paint with the insulating paint applicator 9,
Baked in a baking furnace 10, then taken up on a take-up reel 15
It is wound up. Guides 11, 12, 13, and 14 are used when applying and baking the insulating paint repeatedly.

In an electrolytic bath 3 containing an electrolytic cleaning solution, a power supply jig 6 is also connected to a conductor serving as a counter electrode to an electrode 5 in the electrolytic solution.

4 indicates a DC power supply device.

FIG. 2 shows a case where an electrolytic cleaning device is attached to a wire drawing machine in an insulated wire manufacturing apparatus in which a wire drawing process and a baking process are performed in tandem. The conductor 17 fed out from the supply reel 16 passes through an electrolytic bath 18 containing an electrolytic cleaning solution, and enters a washing tank 22 after being electrolytically cleaned. Thereafter, in the wire drawing machine 23, the wire is squeezed and drawn by a die 26 while rotating the capstans 24 and 25, and then proceeds to the baking line. In the electrolytic cleaning tank 18 containing the electrolytic solution, 19 is a DC power supply device, and a jig 21 is used to supply power to a conductor serving as a counter electrode to an electrode 20 in the electrolytic cleaning tank.

Any metal or alloy can be used as the electrode in the electrolytic cleaning solution tank, but if this electrode serves as an anode, it will dissolve, so it is better to use a metal or alloy that is as difficult to dissolve as possible. For example, a stainless steel plate is desirable.

The present invention will be explained below using examples.

Comparative example (1) After softening bare copper wire with a conductor diameter of 0.025 mm, polyurethane insulation paint was applied and the wire was heated in a baking furnace (furnace length 1.5 m,
It was baked by passing it through a furnace (temperature: 360℃).

The number of times the paint was applied and baked was 8 times, and the insulation film thickness was about 3μ.

The winding speed was 250 m/min, and the wire was wound onto a 30 g reel. When all 85 reels were inspected using a stereomicroscope at 40x magnification, 30 reels were found to be defective with black spots, and discoloration of the conductor was observed in 15 reels. The remaining reels had good appearance.

Comparative example (2) Everything is the same as Comparative Example (1) except as described below.

Prior to softening the conductors, they were cleaned with an organic solvent by passing them through a cleaning bath containing a 20 cm length of Triclean.

When we checked the 85 reels that had been taken up, we found that 20 reels had black spots and discolored conductors were found in 18 reels. The remaining reels had good appearance.

Comparative Example (3) A bare copper wire with a conductor diameter of 0.6 mm was softened, then coated with polyester insulation paint, and baked by passing it through a baking furnace (furnace length: 5 m, furnace temperature: 420°C). The number of times the paint was applied and baked was 6 times, and the insulation film thickness was 25μ. The winding speed was 25 m/min. Insulated wires were rolled up to check for grain formation due to foaming.
When rewinding 10,000 m, 20 particles due to foaming were detected. Also, when checking the dielectric breakdown voltage in saturated salt glycerin every 100m, the average value was 3200V, the maximum value was 5200V, and the minimum value was 1100V.
It was hot.

Comparative example (4) After softening a bare copper wire with a conductor diameter of 1.0 mm, it is coated with polyimide insulation paint (Du-pont, pyre-ML) and passed through a baking furnace (furnace length: 5 m, furnace temperature: 400°C) In some cases, it was burned. The number of times the paint was applied and baked was 8 times, and the insulation film thickness was 35μ. Winding speed
The speed was set at 15m/min. When we unwound 5,000 m of insulated wire to check for grains caused by foaming, we found grains caused by foaming everywhere.

Comparative example (5) After softening a bare copper wire with a conductor diameter of 0.75 mm, it was heated to 170℃.
A solvent-free insulating paint (resin: polyester) was applied to
Burning was carried out by passing it through the temperature range (°C). The number of times the paint was applied and baked was 3 times, and the insulation film thickness was 27μ. The winding speed was 24 m/min. When I checked the appearance of the insulated wire coating on the reel, I noticed some ripples in some places. Also, 100m
When we checked the dielectric breakdown voltage in saturated saline glycerin, the average was 2500V. The maximum value was 5000V and the minimum value was 900V. (Number of measurement points n = 50) Comparative example (6) A bare copper wire with a conductor diameter of 0.65 mm was
After softening to 0.24 mm, polyamide-imide insulation paint was applied and baked in a baking furnace (furnace length).
7 m/min, furnace temperature: 420°C). The number of times the paint was applied and baked was 6 times, and the insulation film thickness was 24μ. The winding speed was 26 m/min. In order to check the generation of grains due to foaming, we unwound 5000 m of insulated wire, and found that 50
ke grains were detected. In addition, when the dielectric breakdown voltage in saturated salt glycerin was checked every 100 m, the average value was 3500V, the maximum value was 6500V, and the minimum value was 1200V.

Example (1) Everything is the same as Comparative Example (1) except as described below.
30cm length containing 0.5% sodium carbonate aqueous solution
The conductor was cleaned by passing it through an electrolytic cleaning bath. At that time, the conductor was used as a cathode and the stainless steel plate in the electrolytic cleaning tank was used as an anode, and the current density was 8.5mA/mm ²
was applied to the conductor surface.

When we checked the 85 reels that we had taken up, we found that there were no reels with defective black spots, and there were only two reels with slight discoloration of the conductor, and all the remaining reels had a good appearance.

In this example, since the conductor before electrolytic cleaning had undergone current softening, there was no need to use a softening furnace before applying and baking the insulating paint.

Example (2) Everything is the same as Comparative Example (3) except as described below.

Before softening the conductors, they were cleaned by passing them through a 30 cm long electrolytic cleaning bath containing a mixture of 0.2% aqueous sodium carbonate and 0.2% caustic soda, followed by water rinsing. During electrolytic cleaning, a current density of 10 mA/mm ² was applied to the conductor surface using the conductor as a cathode and the stainless steel plate in the electrolytic cleaning tank as an anode.

After unwinding 1000m of rolled-up insulated wire,
No particles due to foaming were detected. Furthermore, the average value of the dielectric breakdown voltage was 4100V, the maximum value was 8000V, and the minimum value was 2000V.

Example (3) Everything is the same as Comparative Example (4) except as described below.

Prior to softening the conductors, they were cleaned by passing them through a 30 cm long bath of electrolytic cleaning solution containing a 0.7% aqueous sodium carbonate solution, followed by a water rinse.

In addition, during electrolytic cleaning, the conductor is used as a cathode, and the stainless steel plate in the electrolytic cleaning tank is used as an anode, and the current density is
10 mA/mm ² was applied to the conductor surface.

When 5000m of rolled insulated wire was unwound, no particles were found due to foaming.

Example (4) Everything is the same as Comparative Example (5) except as described below.

Prior to softening the conductors, they were cleaned by passing them through a 30 cm long bath of electrolytic cleaning solution containing a 0.5% aqueous sodium carbonate solution, followed by a water rinse.

In addition, during electrolytic cleaning, the conductor is used as a cathode, and the stainless steel plate in the electrolytic cleaning tank is used as an anode, and the current density is
5 mA/mm ² was applied to the conductor surface.

When the appearance of the wound insulated wire film was checked, the surface was smooth without any ripples. In addition, the dielectric breakdown voltage in saturated salt glycerin was checked every 100 m, and the average was 3600V. Also, the maximum value was 7000V and the minimum value was 1400V. (Number of measurement points, n=50) Example (5) Everything is the same as Comparative Example (6) except as described below.

After electrolytically cleaning the conductor, it was drawn, then an insulating paint was applied and baked.

During electrolytic cleaning, a current density of 7.5 mA/mm ² was applied to the conductor surface using the conductor as a cathode and a stainless steel plate in an electrolytic purification tank (length, 30 cm) as an anode.
A 0.5% sodium carbonate aqueous solution was used as the electrolytic cleaning solution. When the coiled insulated wire was checked for grain formation, no grain was found.

Also, when checking the dielectric breakdown voltage every 100m, the average was 4300V, and the maximum value was
7800V, the minimum value was 1500V.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a method of manufacturing an insulated wire according to the present invention, and FIG. 2 is an explanatory diagram of a method of drawing a conductor according to the present invention. 1, 16... Supply reel, 2, 17... Conductor,
3, 18... Electrolytic cleaning tank, 4, 19... DC power supply device, 5, 20... Electrode in electrolytic cleaning tank, 6, 21...
Jig for supplying power to the conductor, 7, 22... Washing tank, 8... Conductor softening furnace, 9... Insulating paint coating device, 10... Baking furnace, 11, 12, 13, 14... Guide roller, 1
5... Winding reel, 23... Wire drawing machine, 24, 25... Capstan, 26... Die.

Claims (1)

[Claims] 1. After connecting the copper conductor to the cathode and electrolytically cleaning it,
A method of manufacturing insulated wires, which involves coating and baking an insulating paint on a conductor. 2. A method for producing an insulated wire according to claim 1, which comprises electrolytically cleaning the conductor, immediately continuing drawing the wire, and applying and baking an insulating paint. 3. The method for manufacturing an insulated wire according to claim 1, which comprises washing with water after electrolytic cleaning. 4. A method for manufacturing an insulated wire according to claim 1, characterized in that a conductor having a conductor diameter of 0.10 mm or less is electrolytically cleaned. 5. The method for manufacturing an insulated wire according to claim 1, wherein the conductor diameter is 0.5 mm or more and the insulation coating thickness is 0.020 mm or less. 6. A method for manufacturing an insulated wire according to claim 1, which comprises applying and baking a solvent-free insulating paint or a high-concentration insulating paint. 7. Claim 1 characterized in that polyimide or polyamide-imide insulation paint is applied and baked.
2. Manufacturing method of insulated wire.