JPH0427320B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an electrolytic treatment method for metal wires that can achieve efficient electrolysis while reducing power costs. The electrolytic treatment in the present invention includes electrolytic treatments such as electrolytic cleaning, electrolytic pickling, and electroplating of the metal wire, and includes electrolytic treatment between the metal wire and a counter electrode by passing it through an alkaline or acidic electrolyte. means someone who does [Prior Art] Electrolytic treatment, particularly electroplating, of metal wires is carried out using, for example, an electrolytic apparatus shown in FIG. That is, the electrolytic plating solution (hereinafter referred to as electrolytic solution) L drawn out from the tank 1 by the pump P is injected into the electrolytic cell 2 from above, not only to fill the electrolytic cell 2 but also to actively inject a large amount to cause overflow. , the overflow is returned to tank 1. The anode 3 is immersed in the electrolytic solution La in the electrolytic cell 2.
The wire W is electroplated by passing it through the electrolytic cell 2 while being in contact with the roller (cathode) 4. By the way, in order to increase processing efficiency, that is, productivity in the electroplating operation described above, it is necessary to increase the passing speed of the wire W, and for this purpose, it is necessary to increase the length of the electrolytic cell or increase the electrolytic current density. However, in these cases, the scale of the apparatus becomes large and it is not suitable for practical use. On the other hand, if the electrolytic current density is increased above a certain limit, the plated surface of the wire becomes blackish with no metallic luster (this is called a burnt phenomenon), and the current density seems to have an upper limit. Furthermore, in order to ensure a high current density, it is necessary to increase the electrolytic voltage, which also causes the problem of rising power costs. [Problems to be Solved by the Invention] Therefore, the present inventors have developed a current density increasing method as a basic method to improve productivity without increasing the size of equipment, and to solve the problem of burnout, which is the drawback of this method. We aimed to provide an electrolytic treatment method that would reduce power costs while preventing such problems, and we conducted repeated research in that direction. In other words, according to the research conducted by the present inventors, the reason why the wire surface burns under high current density conditions is because the metal ion concentration in the electrolyte near the wire plating surface decreases due to electrolysis. This is because an electrolytic solution having a high metal ion concentration that can correspond to the electrolysis rate cannot be supplied to the wire plating surface. Based on the above findings, the present inventors have found that in order to improve productivity by adopting current density increasing means, it is necessary to sufficiently supply metal ions to the wire plating surface. We have come to the conclusion that it is necessary to increase the flow rate of the electrolyte so that a sufficient amount of the electrolyte comes into contact with the wire plating surface. [Means for solving the problem] The present invention was completed as a result of repeated research based on the above guideline as an important clue to solving the problem. V
(m/sec), current density is E (A/dm ² ), the electrolyte flow rate and current density are adjusted so that E≦-0.002V ² +1.4V + 30, and the distance between the electrode and the metal wire is adjusted. The point is that the metal wire is electrolytically treated with a length of 5 to 20 mm and an electrode length of 1500 mm or less. [Operation] The constituent elements of the present invention will be explained in order. Electrolyte flow rate and current density: E≦−0.002V ² +1.4V+30 As mentioned above, in order to perform electrolytic treatment under high current density conditions while preventing the burning phenomenon, a sufficient amount of electrolyte must be supplied to the wire plating surface. Must. Therefore, the present invention adopts a configuration in which the electrolytic solution is forcedly circulated within the electrolytic device to increase the flow rate of the electrolytic solution. In other words, if you want to increase the electrolyte flow rate using an open type electrolyzer as shown in Figure 1, it is necessary to increase the height of the electrolytic cell tank above the overflow part to increase the liquid pressure in the overflow part. However, this requires a considerably large-scale electrolytic cell tank, which poses a practical problem. Moreover, the speed can be increased only in the vicinity of the overflow portion, and it is not necessarily possible to effectively increase the flow speed in all parts. Furthermore, since the electrolytic solution is vigorously discharged to a long distance from the overflow portion, the receiving portion of the electrolytic cell must be designed to be long, which increases the size of the device. For these reasons, it is difficult to increase the electrolyte flow rate in an open type electrolyzer; in other words, it is difficult to increase the electrolyte flow rate in a gravity flow type electrolyzer.
The present inventors have taken these circumstances into consideration and have concluded that it is necessary to forcefully circulate the electrolyte in order to increase the flow rate of the electrolyte. In the present invention, there is no particular restriction on the flat stage for forced circulation of the electrolytic solution, but for example, an electrolytic device shown in FIG. 2 can be applied. That is, the electrolyzer S is provided with electrolyte introduction guides 12 (described later, see FIGS. 4 and 5) on both sides of the cylindrical anode body 11, and the electrolyte L extracted from the tank 1 by the pump P is introduced into the cylindrical shape from both ends. It is introduced into the through hole 13 of the anode body 11 , extracted from approximately the center of the cylindrical anode body 11 , and returned to the tank 1 . On the other hand, the wire W is brought into contact with the cathode roller 14, introduced into the through hole 13 from the left end of the cylindrical anode body 11 in the drawing, and extracted from the right end in the drawing. A voltage is applied between the cylindrical anode body 11 and the cathode roller 14. In the above electrolytic device, the electrolytic solution L is forced to flow into the through hole 13, so the flow rate of the electrolytic solution can be arbitrarily adjusted by changing the supply amount of the pump P. Therefore, when we investigated the relationship between the electrolytic solution flow rate and the maximum current density (the maximum value of current density that does not cause the burning phenomenon) using the electrolyzer as described above, we obtained the results shown in FIG. 1. That is, the maximum current density (E) tends to increase as the electrolyte flow rate (V) increases, and between the two, E = -0.002V ² +1.4V
The relationship shown by +30 is established. Therefore E≦−
By adjusting the flow rate of the electrolytic solution so that the voltage becomes 0.002V ² +1.4V+30, the wire can be electrolytically treated without causing a burning phenomenon. Although the current density range is not specified in the present invention,
In order to obtain high productivity, the current density should be 90 to 250 (A/
dm ² ). In order to obtain the above-mentioned preferred current density range without causing a burning phenomenon, the electrolytic solution flow rate may be set to 0.5 to 2.5 cm/sec. In addition, one of the factors that increases the electrolysis voltage is the cutoff resistance voltage due to gas generated at the anode.
In the present invention, by forcing the electrolyte to flow as described above, the gas generated and retained at the anode can be washed away together with the electrolyte, and the cut-off resistance voltage can be lowered. As a result, as shown in FIG. 3, the electrolysis voltage can be lowered compared to the conventional method. Spacing between electrode and wire: 5 to 20mm Basically, it is necessary to provide a certain amount of space between the electrode (anode) and the wire in order to supply metal ions to the surface of the wire, which is the cathode. By providing this, short circuit between the electrode and the wire can be prevented. If the distance is less than 5 mm, there is a risk of short circuit between the electrode and the wire due to vibration of the wire.
On the other hand, if the spacing exceeds 20 mm, the electrolyte will be present between the electrode and the wire with a thickness greater than necessary, which will increase the resistance voltage due to the electrolyte, increasing the electrolysis voltage and causing a rise in power costs. Electrode length: 1500 mm or less When increasing the current density to increase productivity, especially when increasing the current density to 200 (A/dm ² ) or more,
The current flowing through the wire, which is the cathode, also increases, and as the resistance voltage of the wire increases, the electrolytic voltage increases. That is, when the electrode length exceeds 1500 mm, the wire of the cathode portion also becomes long, and the increase in electrolytic voltage accompanying the increase in the wire resistance voltage increases, leading to a rise in power costs. Furthermore, since the electrodes and wires are too long, the current distribution becomes non-uniform, making it impossible to obtain a homogeneous plating state. [Example] FIG. 4 is a cross-sectional explanatory diagram showing an electrolytic solution introduction guide applied to the electrolytic device shown in FIG. (see figure), a reduced diameter part 16 is provided between the large diameter parts 15, 15, which have approximately the same diameter as the inner diameter of the enlarged diameter part at the end of the cylindrical anode body 11, and an annular packing 17 is loaded therein. A swirling blade 19 is attached to the end face of the small diameter part 18, and the swirling force of the electrolyte introduced from the tangential direction into the gap between the outer peripheral surface of the small diameter part 18 and the inner wall surface of the enlarged diameter part of the anode body is reduced. is increasing. As a result, the electrolyte becomes a hollow flow and flows into the introduction guide through hole 13, and when the swirling force eventually weakens, the hollow flow changes to a solid flow and is discharged from the center of the electrolyzer. By using the electrolyte introduction guide, the electrolyte can be forced to flow into the electrolytic device while preventing leakage of the electrolyte at the introduction portion. FIG. 6 is a schematic diagram showing another embodiment of the electrolyzer applied to the present invention. In this embodiment, the downstream end of the cylindrical anode body 11 in the wire running direction is An electrolytic solution introduction guide 12 is provided, and an electrolytic solution discharge guide 20 shown in FIG. 7 (described later) is attached to the upstream end. The electrolytic solution extracted by the pump P flows from the downstream side to the upstream side in the wire running direction, and is returned to the tank 1. In this embodiment, the electrolytic solution can be forcibly introduced into the anode body through-hole 13 without leaking, as described above. Further, in this embodiment, since the electrolytic solution is flowed opposite to the direction in which the wire runs, metal ions can be supplied to the wire plating surface and gas generated at the anode can be removed more efficiently. FIG. 7 is a cross-sectional explanatory diagram showing an example of an electrolyte discharge guide, and the discharge guide 20 has a built-in rotor 22 having a spiral flow path 21, and is rotated through a wire passing hole in a portion corresponding to the shaft of the rotor 22. It is constructed by forming a spiral groove in the opposite direction. By using the electrolyte discharge guide 20, the electrolyte that has been fed through the anode body through hole 13 is pushed by the flow and distributed to the centrifugal side by the rotor 22, which rotates on its own axis, and is sent to the discharge line 10. collected and returned to a tank (not shown). At this time, liquid leakage in the electrolyte discharge guide 20 is avoided by the distribution effect of the centrifugal force and the pushing back effect of the reverse spiral groove 23. Example A mild steel wire with a wire diameter of 1.5 mm was plated with Zn using the electrolysis apparatus shown in FIG. The equipment dimensions, plating bath composition, and plating conditions are as follows. Apparatus Cylindrical anode body Inner diameter 30mm Length 1500mm Distance between anode body and wire approximately 14.5mm Plating bath composition ZnSO ₄・7H ₂ O 400g/ H ₂ SO ₄ 150g/ Plating bath temperature 55℃ Figure 8 as a comparative example Zn plating was carried out using the same electrolytic apparatus at the same plating bath composition and temperature. Equipment: Plating bath length: 1500 mm Distance between anode body and wire: 12 mm The results are shown in Table 1.

【table】

[Table] [Effects of the Invention] The present invention is configured as described above, and the current density can be increased without causing burnout.
High productivity can be obtained. When increasing the current density, the increase in electrolytic voltage can be minimized and power costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between flow velocity and maximum current density, FIG. 2 is a schematic diagram showing an example of an electrolysis device applied to the present invention, and FIG. 3 is a graph showing the relationship between interelectrode distance and electrolysis voltage. Figure 4 is a cross-sectional explanatory diagram showing the electrolyte introduction guide, Figure 5 is a cross-sectional view taken along the line - in Figure 4, Figure 6 is a schematic diagram showing another example of an electrolytic device, and Figure 7 is an electrolyte discharge FIG. 8 is a cross-sectional explanatory view showing a guide, and is a schematic diagram showing an example of a conventional electrolysis device. DESCRIPTION OF SYMBOLS 1...Tank, 11...Cylindrical anode body, 12...Introduction guide, 13...Through hole, 14...Cathode roller, 20
…Emission Guide.

Claims (1)

[Claims] 1 In a method of continuously electrolytically treating metal wire, the flow rate of the electrolytic solution is V (cm/sec) and the current density is E.
(A/dm ² ), E≦−0.002V ² +1.4V
A method for electrolytic treatment of a metal wire, which comprises adjusting the flow rate of the electrolytic solution by forced circulation so that the electrolyte is +30, and performing the electrolytic treatment with an interval between the electrode and the metal wire of 5 to 20 mm, and an electrode length of 1500 mm or less.