JPS5831099A - Blackening method for copper wire and rod body - Google Patents

Abstract

PURPOSE:To blacken copper wire and rod materials of intricate shapes efficiently to high quality by disposing plural alkaline bath tanks in series, and decreasing the alkali concns. and average anode currents in the respective bath tanks successively along the traveling direction of said wire and rod materials. CONSTITUTION:For example, a twisted wire 1 produced by twisting 8 pieces of copper wires together and molding the same to a sector shape by compression is run successively through the inside of electrolytic cells 2, 3, 4, which are filled with caustic soda solns. and are disposed in series. The concns. of the caustic soda solns. in the respective electrolytic cells are decreased successively in a 500-50g/l range and the average anode currents thereof are decreased successively in a 10-1A/cm<2> range, along the running direction of the wire 1. After the electrolyzed wire 1 is washed in a washing tank 5, the wire is dried in a hot stove 6. If the concns. and current density of the alkali solns. are decreased successively in the above-mentioned way, the good products are obtained without remelting of the once formed copper oxide.

Description

[Detailed description of the invention] Overlapping @ is a method of electrolyzing steel wires and strips to give them a navy color. The purpose of this invention is to provide a method for converting the osi rays to A+& quality and efficiently turning them into black.

In general, the process of forming a coating such as copper oxide on the surface of a copper wire to give it a waxy color is not only done to improve the appearance, but also as a base treatment for the contact layer, as well as to absorb heat radiation such as sunlight. It is widely required industrially as a body. It is also useful as an electrical insulator, and is particularly useful in the production of stranded insulated conductors because it can improve power loss due to the cane skin effect or proximity effect in twisted conductors.

Conventionally, the blackening treatment has been carried out by a so-called chemical conversion method in which the material is immersed in an alkaline bath containing salts of chlorite and persulfuric acid.

However, this method requires time to carry out, making it unsuitable for treating continuous striatum (61) and consuming expensive chemicals, which poses an undue burden in actual operation. Met.

On the other hand, in order to make the copper wire black in color by the electrolytic method, it must be heated in an alkaline bath such as a caustic soda aqueous solution.
This process involves anodizing a single strip, and is a suitable treatment method when a large amount of continuous material is to be treated using Q, which is extremely advantageous in terms of processing speed and chemical cost compared to the above-mentioned chemical conversion method.

However, forming a dense oxide film at a high speed requires an alkaline solution with a high chain degree, so it requires a large amount of water and sufficient time to wash it after the blackening process. Alternatively, a large space is required for the water washing line, which requires treatment of a large amount of wastewater and huge equipment costs. This is especially noticeable when processing complex-shaped copper wire bodies, such as twisted wire bodies, and Tol+ penetrates into the gaps between the twisted wires and completely cleans the nine-viscosity alkaline aqueous solution. It was extremely difficult and I gave up.

The present invention takes into consideration the characteristics of the anodic acidic reaction of sickle copper and has discovered a method for easily carrying out industrial treatment even on copper wire bodies having complicated shapes.

That is, the method of the present invention is a method for blackening steel filaments in which a steel filament is continuously subjected to anode electrolysis in an alkaline bath to form a copper oxide coating on the surface of the filament. Alkaline baths are arranged in series, and electrolysis is performed while decreasing the alkaline concentration in each bath sequentially along the running direction of the filament and reducing the average 7-node flow in each bath. This is a characteristic feature.

In the method of the present invention, multiple baths are provided, and the alkali concentration and current density f: Ji Copper oxide that is not generated at current density and once generated is also redissolved.

Furthermore, once the alkaline bath is applied, the current density range shifts to a higher current direction.

Therefore, a copper oxide film is effectively generated on the surface of the copper wire in the first electrolytic cell, and then the 2'It demolition and #I3
゛-Sequentially like a disassembly tank, 1 @ disassembly tank is installed to prevent re-melting of the hardened steel coating and to prevent it from being immature! The purpose is to compensate for the lack of ls or film thickness and at the same time reduce the concentration of adhering alkaline solution, making it easier to wash with water in post-treatment.

The method of the present invention is particularly effective when applied to objects with complex shapes such as stranded wires. For example, when treated in a single electrolytic bath as in the conventional method, only the six outer directions of the 9-stranded wire are preferentially oxidized. If you try to oxidize the inside, the oxide film on the outer surface will re-dissolve. In this case, even if the electric current is gradually reduced to suppress redissolution, a thick alkaline solution remains inside the twisted bm. Furthermore, when a low concentration alkaline solution f# is used, it takes a long time to form an oxide film and it is not possible to form a good quality film.

Further, the concentration of the alkaline solution in the method of the present invention is about 50
01/l to about s o i/I, current density is several 104/l
I11! -li2, which is selected depending on the bath temperature, the shape of the filament, and the thickness of the copper oxide coating.

Next, examples of the present invention will be explained. As shown in the figure yc, 8 copper wires of 2.39 mm are stranded in a fan shape and compressed into a ground temperature at a wire speed of 3 mln per strand.゜Fi1 inside 3 and 4
The next time I drove it, I went to electric PST.

The electrolytic conditions are shown in Table 1.

Table 1 1st electrolytic cell 2nd electrolytic cell 3rd electrolytic cell Tank length 1m
2m 3mm Caustic non-liquid 3001i, 15011/I
601/1 Current 180A 90mm 20mm The wash tank is 2 lengths long, divided into a plurality of parts, and washed with water in multiple stages in countercurrent flow at lQj/min.

4 is a hot air stove.

The stranded wire of the present invention thus obtained exhibited blackening both inside and on the device, and the oxide film thickness by the Candor reduction method was 0.5 in terms of CuO.
It was 1μ. In addition, when the crystal of the present invention was immersed in 1 m of warm water and the alkali remaining in the layer was analyzed, it was found to be 5 days Nu/.
I met M.

Main departure 811 again! l! In order to see the effect of the wire as a cable conductor, six stranded wires were twisted together in a circle, and the current resistance tag and current resistance were 8° and the skin effectiveness coefficient r = (R, A
D) -1 was measured and the good performance was 0.04 O ratio soft example (the same stranded wire as in the example above was stranded with NaO
Electrolysis was carried out under the conditions of H300-1711 and 18OA of electricity during nine electrolysis intervals. - As a result, the outer surface of the stranded wire of the comparative example exhibited a light blackish brown color and was fc4. Also, the average oxide film thickness is 0.21μ,
In addition, when the residual alkali was measured in the same manner as in the example, it was found to be extremely large at 391 f'm.

In addition, when the above current was changed in three stages as in the example, the results showed that the oxide film had an average thickness of 0.67μ and a blackening of 69% occurred, but the residual alkali was still large at 37~-. .

As described in detail above, the method of the present invention has remarkable effects such as significantly reducing manufacturing equipment costs and salt waste, and forming a uniform black oxide film in a short time without worrying about environmental pollution.

[Brief explanation of the drawing]

This is a route explanatory diagram showing an example of a device for explaining the F method. 1... Copper stranded wire, 2... 1' illEm4%W,
3...2nd electrolysis-14#...31st! Tank opening, 5...
・Washing tank, 6...Electric furnace.

Claims (1)

[Claims] (1) Copper wire of 1140m% is subjected to continuous anode P electrolysis in an alkaline bath to form a steel oxide O film on the surface of the starved 1st strip, and the strip becomes black. % in flow
**@o Alkaline bath m+ is distributed in a row, copper-1
The alkali in each positive treatment along the 0 * direction of the body 9 reduces the application and + the average anode voltage of the bathtub #l! tl
A method for coloring copper wires and strips in black color, which is characterized by performing a small amount of electricity. LA) 1111111, the copper stripes described in item 1 of the patent claim, where the tn value is to use 1m of strands in the strip.
Method for blackening striae.