JPH05228528A - Method for rust preventing treating and drawing of copper wire - Google Patents

Abstract

PURPOSE:To provide the method for drawing a magnet wire to prevent the discoloration by oxidation of the surface of the copper core wire of the magnet wire. CONSTITUTION:A copper bus 1a let off from a wire supply bobbin (b) is introduced into a drawing machine 20 and a liquid lubricant 4 is supplied to an intermediate die 2; in succession, a liquid lubricant 4s for rust prevention added with imidazole or benzotriazole is supplied to a finishing die 2s. The copper bus is drawn down to the copper core wire 1 while a rust preventive film is formed on the surface of the copper wire and the core wire is taken up on a take-up bobbin (d). The liquid lubricant 4s for rust prevention in a lubricant tank 10 for rust prevention is sent through a piping 5s for supply by a supply pump 11 to the drawing machine 20 where the lubricant is sprayed from a nozzle 6s to felt 12 for supplying the lubricant. The lubricant is thus supplied to the finishing die 2s. The liquid lubricant 4s for rust prevention after the spraying is gathered to a lubricant rest 13 and is returned through a piping 7s for return and a filter 14 to the tank 10, from which the lubricant is again cyclically used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper wire drawing method,
More specifically, the present invention relates to a wire drawing method suitable for drawing a copper core wire for a magnet wire, in which the surface of the copper wire is subjected to rust prevention treatment.

[0002]

2. Description of the Related Art Conventionally, as a method for drawing a copper wire, a method of supplying a liquid lubricant to a plurality of drawing dies to draw a copper wire to a copper wire having a prescribed outer diameter, a so-called wet drawing process The wire drawing method by

Since a thin copper core wire for a magnet wire is used with a diameter of a few microns, copper of high purity (99.99%) is used as a copper material and is generally manufactured by a continuous casting method (SCR). Electrolytic copper is used.
This electrolytic copper was drawn from the ingot to 8mmφ, then
Draws up to 2.6mmφ with a single head wire drawing machine. When the diameter is reduced from 2.6 mmφ, a generally used wet slip type multi-stage horizontal wire drawing machine (hereinafter abbreviated as horizontal wire drawing machine) is used.
A plurality of sets of dice arrangements (for example, 7-set dice arrangement, 13-set dice arrangement, 20-set dice arrangement, etc.) are drawn down in stages, and wire drawing is performed up to thin wires. Steel dies, alloy dies or diamond dies are used as the material of the dies. Generally, a diamond die is used for 0.4 mmφ or less, and the area reduction rate per die is 7 to 22%.
Has been drawn.

The liquid lubricant used in the wet drawing process is based on an emulsion type water-soluble lubricant or fatty acid glycol ester, which is prepared by emulsifying and dispersing a surfactant in mineral oil or vegetable oil. A synthetic water-soluble lubricant with a surface active agent added to it is sprayed on the copper wire, the die and the corrugated roll during wire drawing, and these are cooled and the lubricity of these is improved, and die wear and elongation We are trying to improve the drawing workability of wire drawing by preventing wire breakage during wire drawing process.

As an actual example of a method for drawing a copper wire, an emulsion type Rubelite # 2000L (trade name of Nippon Oil Research Institute Co., Ltd.) adjusted to an oil content of 2% is used as a liquid lubricant for a horizontal wire drawing machine. Supplying to each die in the set die array, the area reduction rate per die is 7%, and the linear velocity is 900 m / min, 0.05 m
Wire drawing from mφ copper bus bar to 0.03mmφ copper core wire.

[0006]

An unsolved problem in which a magnet wire coated with an insulating paint such as polyurethane paint on the outer circumference of a copper core wire and baked is particularly problematic in terms of quality and has not yet been fundamentally solved. As an example, oxidative discoloration of the copper core wire can be mentioned. Especially in the case of a magnet wire of around 20 μm used for a watch coil, etc.
Even with a slight oxidative discoloration on the surface of the copper core wire, the solder spreads poorly when soldered, and it is difficult to use. The oxidative discoloration tends to occur frequently during high temperature and high humidity especially in the rainy season.

Therefore, the inventors of the present invention have conducted various studies on the oxidative discoloration of the copper core wire of the magnet wire, and as a result, the oxidative discoloration of the copper core wire has occurred due to external factors such as humidity after the insulating film is formed. Most of them were generated during the wire drawing process stage or when the environmental conditions during storage were bad, such as high temperature, high humidity, acid or alkaline atmosphere during wire drawing storage. It is found that oxidative discoloration occurs even when the environmental conditions during the wire drawing process or the wire drawing storage are good, and it is the stage during the wire drawing process or wire drawing storage. It was found that the cause of the occurrence of oxidative discoloration on the surface of the copper core wire was generated after it became a magnet wire. Therefore, it has been found that it is sufficient to take measures to prevent the occurrence of oxidative discoloration of the copper core wire in the wire drawing step.

The present invention has been made to solve the problems of the above-mentioned prior art. In the wire drawing step, a rust-preventive film is formed on the surface of the copper wire to prevent oxidative discoloration on the surface of the copper core wire of the magnet wire. It is an object of the present invention to provide a rust preventive treatment wire drawing method for preventing.

[0009]

In order to achieve the above object, the present invention provides a liquid lubricant to a wire drawing die to draw a copper wire up to a copper wire having a prescribed outer diameter. Supplying a finishing die with a rust-preventing liquid lubricant added with an imidazole-based or benzotriazole-based compound that chemically reacts with to form a rust-preventive film, reacting the copper wire with the rust-preventing liquid lubricant, This is a rust-prevention treatment wire-drawing method for a copper wire in which a rust-proof film is formed on the surface of the copper wire.

The imidazole-based or benzotriazole-based compound (hereinafter abbreviated as rust-proofing imidazole-based compound) that chemically reacts with copper to form a rust-proofing film is imidazole, 2-phenyl-4-methyl-. Examples thereof include imidazole, benzotriazole, P-cresol-benzotriazole, and hydroxylbenzotriazole. These compounds are organic heterocyclic compounds having a strong affinity with copper. The chemical formula is shown below.

[0011]

[Chemical 1]

[0012]

The rust-preventing wire drawing method of the present invention comprises supplying a finishing die with a rust-preventing liquid lubricant containing an imidazole-based or benzotriazole-based compound that chemically reacts with copper to form a rust-preventive film. , A copper wire and a liquid lubricant for rust prevention are reacted to form a rust-preventive film on the surface of the copper wire, which prevents oxidative discoloration during and after the wire drawing process. Oxidative discoloration of the copper core wire surface is prevented.

The formation of the rustproof film will be described in more detail. In the wire drawing step, the surface area increases as the outer diameter of the copper wire decreases after passing through a plurality of wire drawing dies, so that the new copper surface becomes a chemically active surface. That is,
When viewed microscopically, this copper surface is considerably rough and uneven. Therefore, before the impurities that cause oxidative discoloration adhere to the copper surface, a rust preventive liquid lubricant is infiltrated into the uneven portion of the copper surface, and it reacts with the added rust preventive imidazole compound, and It forms a rust preventive film. This anticorrosive film acts to suppress the electrochemical reaction of the anode and cathode that promotes oxidative discoloration and corrosion. The reaction between the copper surface and the rust-preventing imidazole compound is shown in the following chemical formula 2. The copper surface reacts with oxygen in the air to form copper oxide (Cu ₂ O).

[0014]

[Chemical 2]

[0015]

EXAMPLES The method of wire drawing for rust prevention of copper wire according to the present invention will be described with reference to the drawings. The present invention is not limited to this embodiment. FIG. 1 is a schematic configuration diagram for explaining the rust-proofing wire drawing method of the present invention. Liquid lubricant for rust prevention by adding a 4s supply line for liquid lubricant for rust prevention to conventional horizontal wire drawing machine
It is configured to supply 4s to finishing die 2s.

Copper bus bar 1a fed from the supply line bobbin b
Is introduced into the wire drawing machine 20 via the guide roll c. The introduced copper busbar 1a successively passes through an intermediate die 2 consisting of a plurality of sets of dice to reduce the diameter of the copper busbar 1a, and further passes through a finishing die 2s to become a copper core wire 1 which is wound onto a winding bobbin d. Be done. At this time, since the linear velocity must be increased as the outer diameter of the copper bus bar 1a becomes smaller, the diameter of the pay-out roll 3 is set to be larger each time the intermediate die 2 passes. During the wire drawing process, the pay-out roll 3
And because frictional heat is generated in the intermediate die 2, and in order to improve the drawing workability, the liquid lubricant 4 is sprayed on the feeding roll 3 and the intermediate die 2 in a shower shape from the nozzle 6 provided at the tip of the supply pipe 5. is doing. Then, the sprayed liquid lubricant 4 returns to the lubricant tank (not shown) after passing through the return pipe 7 and is circulated again. Conventionally, the same liquid lubricant 4 that was sprayed on the intermediate die 2 was also supplied to the finishing die 2s, but in the present invention, the finishing die 2s is supplied from a separate series supply line from the rust preventive liquid lubricant 4
s is supplied, the copper wire is reacted with a liquid lubricant for rust prevention, and a copper core wire 1 is drawn while forming a rustproof film on the surface of the copper wire.

The supply line of the rust preventing liquid lubricant 4s supplied to the finishing die 2s will be described in detail. Rust prevention liquid lubricant 4 stored in rust prevention lubricant tank 10
s is sent by the supply pump 11 to the wire drawing machine 20 via the supply pipe 5s, and the nozzle 6s provided at the tip of the pipe 5s.
Then, the two plate-like single felts are sprinkled on the superimposed lubricant-supplying felt 12 to make the felt 12 wet. Since the copper wire being drawn passes between two single felts, a large amount of rust preventive lubricant 4s is attached to the passing copper wire and supplied to the finishing die 2s. .. The rust preventive lubricant 4s after spraying is collected in the lubricant receiver 13 provided under the felt 12 and the finishing die 2s, and passes through the return pipe 7s and the filter 14 provided in the middle of the pipe 7s. And return to the tank 10,
Used again in circulation.

In the present invention, two lines of the liquid lubricant supply line to be circulated and used are a liquid lubricant 4 supply line for the intermediate die 2 and a rust preventive liquid lubricant 4s supply line for the finishing die 2s. The reason for separation is described below. In the wire drawing step, when the supply line of the lubricant is one series as in the conventional case, the amount of copper ions dissolved in the lubricant is extremely large, and the copper ion concentration is rapidly increased. 1
When the anticorrosive liquid lubricant 4s is used in the series supply line, the copper ion reacts with the anticorrosion imidazole compound in an extremely short time, so that the copper wire almost reacts with the anticorrosion imidazole compound. It was found that the rust preventive film cannot be formed on the copper wire surface, that is, the rust preventive effect disappears. Therefore, in order to improve this drawback, the present inventor separates the supply line into two series as described above, and supplies the rust preventing liquid lubricant 4s only to the finishing die 2s. By suppressing the increase of the copper ion concentration as much as possible, the reaction between copper ions and the anticorrosion imidazole compound is reduced, and the anticorrosion imidazole compound is always present in the anticorrosion liquid lubricant 4s. is there.

By separating the supply line into two series, the amount of the rust preventing liquid lubricant 4s used for the finishing die 2s is extremely small compared with the amount of the liquid lubricant 4 used for the intermediate die 2. Therefore, it is economical, and sufficient lubrication and rust prevention effects can be obtained. Further, since the capacity of the rust preventive lubricant tank 10 may be small, it is possible to easily control the concentration of the effective component of the lubricant, and furthermore, even when the lubricant deteriorates, it can be easily replaced.

Examples 1 to 4 Practical examples using the above rust-proofing wire drawing method will be described. A liquid lubricant 4 having the composition shown in Table 1 is supplied to an intermediate diamond die 2 having a 19-piece die arrangement, and a rust preventive liquid lubricant 4s having the composition shown in Table 1 is supplied to the finishing diamond die 2s.
Is supplied using the above-mentioned supply line, and a 0.05 mmφ copper bus bar 1
A was subjected to rust-prevention wire drawing up to 0.03 mmφ copper core wire 1 at a surface reduction rate of 7% and a drawing speed of 1000 m / min, and wound on a winding bobbin d. In Table 1, the amounts of imidazole and benzotriazole added to Lubrite # 2000L and potassium soap solution are 3% and 1%, respectively. The solubility and rust preventive effect for these liquid lubricants are determined by experiments in advance. It is a thing.

Comparative Examples 1 and 2 Under the same conditions as in Example 1 except that the liquid lubricant shown in Table 1 was supplied to all dies, a copper bus bar of 0.05 mmφ was drawn to a copper core wire of 0.03 mmφ, and a winding bobbin was formed. Rolled up.

[0022]

[Table 1]

Copper core wire surface discoloration test Regarding the copper core wire 0.03 mmφ of the bobbin winding obtained in Examples 1 to 4 and Comparative Examples 1 and 2, as a sample, the copper core wire surface was left to stand under the following three conditions for oxidative discoloration. Tested. The results are shown in Table 2.

[0024]

[Table 2]

As is clear from the above table, the copper core wire obtained by the rust-proofing wire drawing method of the present invention is more resistant to oxidative discoloration under various conditions than the copper core wire obtained by the conventional wire drawing method. You can see that it is effective.

[0026]

The anticorrosion treatment wire drawing method of the copper wire of the present invention is a method of wire drawing while forming an anticorrosive film on the surface of the copper wire.
Oxidative discoloration during and after the drawing process is prevented, and oxidative discoloration on the surface of the copper core wire of the magnet wire is prevented.
Therefore, it is a suitable method for drawing a copper core wire for a magnet wire. Further, the rust-preventing wire drawing method of the present invention is only required to add a separate system rust-preventing liquid lubricant supply line to the conventional horizontal wire drawing machine and supply the rust-preventing liquid lubricant to the finishing die. Therefore, rustproofing can be performed easily and surely.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram for explaining a rust-proofing wire drawing method of the present invention.

[Explanation of symbols]

 1 Copper core wire 1a Copper bus bar 2 Wire drawing die (intermediate die) 2s Finishing die 3 Feed roll 4 Liquid lubricant 4s Liquid lubricant for rust prevention 5,5s Supply pipe 6,6s Nozzle 7,7s Return pipe 10 Rust prevention Lubricant tank 11 Supply pump 12 Lubricant supply felt 13 Lubricant receiver 14 Filter 20 Wire drawing machine b Supply line bobbin c Guide roll d Winding bobbin

Claims (1)

[Claims] 1. An imidazole system which forms a rust preventive film by chemically reacting with copper in a wire drawing step of supplying a liquid lubricant to a wire drawing die and drawing a copper wire to a copper wire having a prescribed outer diameter. Alternatively, a rust-preventing liquid lubricant containing a benzotriazole-based compound is supplied to the finishing die, and the copper wire is reacted with the rust-preventing liquid lubricant to form a rust-preventive film on the copper wire surface. A method for wire-drawing a rust-proof copper wire, which is characterized in that