JPS58153797A - Coloration of light metal - Google Patents

Abstract

PURPOSE:To color a light metal so as to impart stable desired color tone thereto, by a method wherein the elecrolyte is immersed in an electrolyte and electrolysis is carried out by using A.C. different in quantity of electricity when positive voltage is applied and quantity of electricity when negative voltage is applied. CONSTITUTION:Between an object 1 to be colored comprising aluminum, an aluminum alloy, an alkaline earth metal or other light metals and an opposed electrode 2 comprising a graphite electrode, commercial A.C. electric power is applied through a circuit including a thyristor SCR and diode D connected in parallel. By this method, a current passing time when positive voltage is applied is appropriately changed by controlling a current stopping time by the thyristor SCR. On the other hand, during a current passing time when negative voltage is applied, current is directly passed through the diode D. Corresponding to the stopping time during this current passing time, coloration with desired color tone can be applied to the object 1 to be colored and, by changing an additive added to the electrolyte 3, different colored products can be obtained.

Description

[Detailed description of the invention] Coloring method for light metals (related to this).

Various methods have been proposed for coloring light metals such as aluminum. Among these, the most typical methods include dyeing anodized aluminum with dyes and electrolytic coloring, which involves secondary electrolysis using a special electrolyte. In particular, coloring by secondary electrolysis. This method is widely used as a coloring method for extrusion molding, but in this method, aluminum is anodized in an aqueous solution such as sulfuric acid, and then subjected to AC electrolysis in a ``city medium'' medium, which is treated with heavy metal salts such as nickel. This is a method of coloring by anodic oxidation (discharging and reducing metal ions directly into the barrier layer existing at the interface between the alumina membrane and the aluminum base, which has a cell structure), and at the same time applying a half-cycle anode. However, because the color is generated in the deep layer of the transparent oxide film, the coloring is stable, resistant to fading, and the method itself is simple. The method is to control the color tone using voltage (usually a few V~
This process is carried out by changing the range of 1O2V] and the time (usually several minutes), so although it is simple in terms of processing and equipment, it causes changes in color tone and makes quality control during manufacturing difficult. was there.

As a means of solving this problem, it has been attempted to change the composition of the electrolytic solution over time (adjusting the electrolytic pressure and time), but even so, subtle changes in color tone occur, and at the fine production stage. It was difficult to adjust for differences between work units and product degrees1.

The present invention has been made to solve these problems, and it is possible to obtain a desired color tone without causing differences in color tone between lofts or between product units during mass production. The purpose is to provide a method for coloring a light metal, the gist of which is that a light metal is immersed in an electrolytic solution, and when a positive voltage is applied to the light metal during a cycle of 14 months, a positive voltage is applied to the light metal. This method of coloring light metals is characterized in that when an amount of electricity and a negative voltage are applied (the amount of electricity supplied to the light metal is different from the alternating current), the method of the present invention , A commercial alternating current voltage in which the positive voltage or current waveform and the negative voltage or current waveform are symmetrical is applied between the light metal and the counter electrode. Unlike the method, as a power source is applied between a light metal and a counter electrode, the amount of electricity supplied to the light metal when a positive voltage is applied to the light metal during the cycle and the amount of electricity supplied to the light metal when a negative voltage is applied is calculated at the end of the cycle. The color tone is stabilized by electrolyzing the light metal by setting each amount of electricity to a predetermined value using alternating current that differs from the amount of electricity supplied to the light metal, and the frequency used is less than the frequency of commercial electricity. For example, it may be arbitrarily set in the frequency range from number 117 to approximately 50Qllz, or it is not limited to this range.Specifically, for example, a case where a commercial power source is used will be explained. - The current that flows when a positive voltage is applied to the light metal during the cycle (hereinafter referred to as positive voltage) and the current that flows when a negative voltage is applied (hereinafter referred to as negative voltage; I). By controlling the energization time of one or both of them using a thyristor or other semiconductor-controlled rectifier, the amount of electricity at positive voltage and the amount of electricity at negative voltage are made to be different, which causes electrolysis and coloring. The power source does not necessarily have to be a commercial power source (this does not have to be a sine wave voltage, but may be a square wave voltage.

In addition, -0 can be used as a known electrolyte, and even in this case, by appropriately setting the ratio of quasi-gas at positive voltage to 19 electricity at negative voltage, various types of electrolyte can be used with the same solution. You can get the color tone.

FIG. 1 shows an example of a circuit that uses a commercial power source to generate alternating current in which the amount of electricity at positive voltage and the amount of electricity at negative voltage are different.The energization time at positive voltage is controlled by a thyristor SCST. The conduction time at negative voltage is such that the current is passed through diode D as it is. 2 is the counter electrode, D is the diode I,'1.D is the Zener diode, UJT is the unidirectional transistor, R,, %
4 is a resistor and C is a capacitor, which are connected to R3 as shown in the figure. When a voltage having the waveform shown in FIG. 2(a) is applied between the AC terminals shown in the figure, a current having the voltage Ichihara waveform shown in FIG. 2(b) flows through the light metal that is the object to be colored 3.
The energization pause angle α at the time of positive voltage can be varied within the range of 0 to 90 degrees by appropriately setting the values of I and C.

Example 2 An aluminum plate anodized with a 0% ll2S04 solution was used as the object to be colored 1, and a counter electrode 2 and a graphite electrode were used. Electrolysis was carried out using an aqueous solution 3 containing 30 g/l of nickel sulfate, 15 El/l of boric acid, and 15 g/l of unsium sulfate, while changing the energization pause angle.

0% (α-0) current at positive voltage, power supply voltage 5■, effective current 0.3 A/d at normal AC
d for 3 minutes at room temperature, the color was brown. When the electrolysis time was varied from 30 seconds to 10 minutes, the color only changed from light brown to dark brown.

In contrast, according to the present invention, when the current is set to 25% (α = 45°) between current-carrying body time at positive voltage, the color becomes reddish copper after 3 minutes of electrolysis, and becomes pale after 30 seconds to 10 minutes of electrolysis. Various colors were obtained from red to copper. In addition, when the current is set to 50% (α - 90°) with a energization pause time of 50% (α-90°) during positive voltage, a brass-colored product can be stably obtained with no difference in color tone from lot to lot after 3 minutes of electrolysis. By electrolysis for 30 seconds to 10 minutes, various colors from golden yellow to bronze were obtained.

In addition, when electrolysis was performed using a solution in which 15 parts of the nickel in the above electrolyte was replaced with the same amount of cobalt, the energization pause time at positive voltage was 15 to 35% (α-27° to 6
3°), current density 03-08 A/d door, time 30 seconds-7
I was able to create a stable and beautiful bronze color and its shading within a few minutes. .

Furthermore, when hypophosphite or hyposulfite was added in an amount of 1.9/l or more, the bronze color became more stable.

In the above embodiment, the amount of electricity at IF voltage and the amount of electricity at negative voltage are made different by controlling the energization time of 1F lightning voltage, but by controlling the energization time at negative voltage, They may be made different, or both may be controlled. In the latter case, it is better to replace the diode D connected in anti-parallel with the thyristor SCR with a thyristor, and to control the phase of its gate with an independent circuit similar to the gate circuit of the thyristor SCR.
゜As is clear from the above explanation, the method of the present invention has the excellent effect of being able to stably color light metals in any color tone without causing any difference in color tone from loft to loft or from product to product. is obtained.

[Brief explanation of the drawing]

(7) FIG. 1 is a circuit diagram showing an example of a power supply device used in carrying out the method of the present invention, and FIG. 2 is a diagram showing its power supply voltage and current waveforms and output voltage and current waveforms. 1 - object to be colored, 2 - counter electrode, 3 - electrolyte solution. IJFγ1 Applicant: Tomohiro Minegishi (1) Dewa Kogyo Co., Ltd. + 1, immediately available Patent attorney Ao 111 Ao ＼ 2 people (8
)

Claims (1)

[Claims] (1) Immersing a light metal in an electrolytic solution 1. - When the voltage of all the light metals is marked 7111 during leakage, the electricity supplied to the light metal is applied, and when a negative voltage is applied, the electricity supplied to the light metal is different from the alternating current. A method for coloring light metals characterized by electrolysis 0.