JP2717041B2 - Surface treatment method for copper and copper alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing discoloration of copper and copper alloy strips using an aqueous inhibitor solution, without impairing the effect of the inhibitor for preventing discoloration and preventing discoloration due to poor drainage. .

[0002]

2. Description of the Related Art Copper alloys such as copper, brass, and phosphor bronze are relatively high corrosion-resistant metal materials. However, when the surface is exposed to the air, an oxide film grows, resulting in discoloration and a reduction in commercial value. May be. In order to prevent this discoloration, the substrate is usually immersed in an aqueous solution containing a benzotriazole-based compound as an inhibitor to perform a discoloration prevention treatment.

[0003] Various heat treatments and rolling processes are performed in the production process of a strip product, and a discoloration prevention process is appropriately performed as temporary rust prevention even during the processing. For example, a discoloration preventing treatment may be performed by appropriately adding an inhibitor such as benzotriazole to a final hot water washing tank in an air annealing line, or a discoloring preventing treatment may be performed in a step of degreasing rolling oil after rolling.

[0004] However, in the case of discoloration prevention treatment using an aqueous inhibitor solution, it is customary to pull up the strip from the processing solution, cut the liquid film on the strip surface as much as possible with a roll or an air knife, and then dry. However, if the drainage and drying are not uniform, discoloration due to the drainage and drying may be recognized as uneven appearance. Even if this discoloration is not visually observed immediately after the treatment, the discoloration becomes clear after several days and may result in a defective product.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for suppressing discoloration caused by uneven treatment in a treatment for preventing discoloration of copper and copper alloy strips.

[0006]

According to a method of the present invention, a strip of copper and a copper alloy is immersed in a discoloration-preventing treatment solution containing an inhibitor. In the surface treatment method including the step of cutting off the liquid, etc., after withdrawing from the discoloration prevention treatment liquid,
This is a surface treatment method for copper and a copper alloy in which cleaning is performed for 2 hours or less with pure water having an electric conductivity of 5 μS / cm or less before a step of draining the liquid.

[0007] In the continuous discoloration prevention treatment, the strip is preferably immersed in a discoloration prevention treatment liquid after being washed with water after degreasing, pickling, etc., that is, after the surface of the strip is as clean as possible. It is customary. However, various impurities brought in from the previous process exist in the washing liquid, and are brought into the discoloration prevention treatment liquid. Further, it is difficult to completely activate the strip surface, and the strip surface is covered with a surface oxide or a trace amount of an organic substance. The surface coating of these strips contaminates the anti-tarnish treatment solution. If the contaminants of the discoloration prevention treatment liquid are not uniformly drained after the discoloration prevention treatment, the contaminants remain unevenly on the strip surface and cause discoloration. In the case of the draining roll, the surface of the roll may be unevenly worn due to the strips, and may be damaged in severe cases. Irregularities on the surface of the draining roll cause poor draining, but it is difficult to completely control this.
Also, even when an air knife is used, it is difficult to constantly and uniformly cut the liquid over the entire width of the strip. Therefore, even if any known draining method is used, if the operation is continued for a long time, the uniformity of the drainage is reduced. Therefore, when the strip surface is washed again with pure water after the discoloration prevention treatment, discoloration due to poor drainage can be almost eliminated. Pure water is ion-exchanged water or ion-exchanged and distilled water to remove the electrolyte from at least tap water or well water, and it is necessary that the electric conductivity be 5 μS / cm or less. If the electrical conductivity is higher than this, the unevenness of the liquid drainage tends to change the color. The lower the electric conductivity of water, the more advantageous in preventing discoloration, and the lower limit is not particularly defined.

However, the protective film formed by the inhibitor is
In particular, if the washing is performed excessively immediately after the discoloration prevention treatment, the protective property is reduced, so that the washing time must be performed within 2 seconds. Here, the term “water washing time” refers to the time from the application of the cleaning solution to the drainage until the drainage.

FIG. 1 is an explanatory diagram specifically showing the method of the present invention. That is, the strip 5 is fed while being immersed into the discoloration prevention treatment tank 2 containing the discoloration prevention treatment liquid 1, pulled up from the discoloration prevention treatment tank 2,
This is a method in which the cleaning liquid of the strip 5 is drained through the draining roll 4 immediately after washing with the cleaning liquid ejected from the nozzle.

In the present invention, the purity of the cleaning solution can be maintained by always applying fresh water directly to the cleaning solution.

When an inhibitor is added to the cleaning solution, the surface of the strip can be cleaned without lowering the protection of the anti-discoloration film.

In addition to the inhibitor, a surfactant, a discoloration preventing auxiliary such as an alkylamine, a lubricant such as a glycol, or the like may be appropriately added to the cleaning liquid.

If a washing tank is provided for washing after the discoloration prevention treatment, it is necessary to control the water quality. Alternatively, when a cleaning solution containing an inhibitor adjusted with pure water is applied, there is no impurity in the cleaning solution, and a small amount of the cleaning solution can effectively solve the problem of discoloration due to poor drainage.

The inhibitor used in the discoloration preventing treatment solution or the cleaning solution is not particularly limited as long as it is known as a discoloration inhibitor for copper and copper alloys. The most commonly used is benzotriazole (1,2,3
-Benzotriazole, BTA), and derivatives thereof are also effective. A representative example of a BTA derivative known as an inhibitor of copper and copper alloys is 4-meth.
yl-1. H-benzotriazole (tol
yltriazole, TTA), 4-carboxy
-1. H-benzotriazole, sodium
um-tolyltriazole, 5-methyl
-1. H-benzotriazole (tolylt
riazole, TTA), benzotriazol
e butyl ester, silver ben
zotriazole and the like. In addition
dazole, benzimidizole, indo
le, triazine and the like and derivatives thereof can be used as inhibitors.

In the discoloration preventing treatment solution, not only an inhibitor but also an amine compound or a surfactant is used when an inhibitor having low solubility in water is used. Alkylamines and mercaptans are used as discoloration preventing aids. The addition of a lubricant such as a glycol to the discoloration prevention treatment liquid in consideration of the subsequent processing steps does not hinder the effects of the present invention.

If chlorine is contained in the washing water or the final washing liquid containing the inhibitor in an amount of 1 ppm or more, discoloration due to uneven drainage is liable to occur. In other words, chlorine is generally contained in well water and tap water in an amount of 5 ppm or more, but chlorine has a large effect as a corrosive medium for copper. In an aqueous solution containing one or more chlorine, discoloration due to poor drainage or uneven drying occurs. Easier to do.

Although the cleaning effect does not depend on the temperature of the cleaning liquid, when drying after draining the liquid, the temperature is preferably from 60 to 80 ° C. for efficient drying.

The present invention relates to a cleaning method after a continuous discoloration prevention treatment of a strip with an aqueous solution, and is effective without any restriction on a pre-process (whether in the same line or on another line) of the discoloration prevention treatment. For example, alkaline immersion degreasing,
It can be applied to those which have been subjected to processes such as electrolytic degreasing, pickling and heat treatment as appropriate.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

[0020]

EXAMPLE Rolled material having a rolling oil of phosphor bronze strip (Cu-8% Sn-0.1% P) having a thickness of 0.2 mm and a width of 600 mm adhered thereto was subjected to alkali immersion degreasing, washing with water, discoloration prevention treatment, and drying. Degreasing and discoloration prevention treatment were performed by a continuous degreasing line. After treatment under various conditions, the results of a test of color fastness are shown in Table 1.

The passing test conditions are as follows. After draining the liquid, it was dried and wound into a coil, and then sampled to evaluate the effect of preventing discoloration by the hydrogen sulfide gas and the occurrence of discoloration due to poor drainage.

Degreasing and Discoloration Prevention Treatment 1) Degreasing Solution Composition Sodium Carbonate 20
g / L tertiary sodium phosphate 35 g / L sodium tripolyphosphate 5 g / L sodium metasilicate 30 g / L surfactant 10 g / L temperature 50 ° C. time 10 seconds 2) water washing spray water washing time 3 seconds 3) discoloration preventing treatment composition benzo Triazole 10
0 ppm Temperature 70 ° C. Time 3 seconds 4) Cleaning As shown in FIG. 1, after the strip 5 is pulled up from the discoloration prevention treatment liquid 1, the spray cleaning nozzle 3 is installed between the time when the liquid is cut off by the liquid discharge roll 4. Then, pure water or an inhibitor solution adjusted from pure water was applied. The washing time, that is, the time from the application of the spray to the removal of the liquid by the liquid removing roll 4 was adjusted by changing the passing speed of the strip 5 or the arrangement of the spray cleaning nozzle 3 and the roll 4.

The amount of liquid supplied by spraying is 600 m of material.
The flow rate of 20 L / min was constant with respect to the m width.

The temperature of the cleaning liquid was 70 ° C.

5) Drainer Neoprene 200 mmφ
The liquid was drained while holding down both sides of the strip with a rubber roll. For the purpose of observing the effect of poor drainage, a rubber roll surface having a depth of 0.5 mm and a length of 200 mm was used.

Discoloration resistance evaluation method A phosphor bronze strip was cut into strip-shaped test pieces, and 3 ppm H
_The specimen was exposed to a hydrogen sulfide atmosphere at ₂ S, 40 ° C. and 50% RH for 20 minutes, and the degree of discoloration of the specimen by sulfurization was visually evaluated.

Evaluation of Discoloration due to Poor Drainage Phosphor bronze strip with a passing width (600 mm) of 1 for each passing condition
The length of m was cut out and exposed indoors for one week, and the occurrence of discoloration due to poor drainage was visually observed.

[0028]

[Table 1]

[0029]

As described above, according to the present invention, in the step of preventing discoloration of copper and copper alloy strips, the occurrence of discoloration due to poor drainage is prevented without reducing the effect of the inhibitor to prevent discoloration. be able to.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a specific example of the present invention.

[Explanation of symbols]

 1 Discoloration prevention treatment liquid 2 Discoloration prevention treatment tank 3 Spray cleaning nozzle 4 Drip roll 5

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-188289 (JP, A) JP-A-50-3032 (JP, A) JP-B-61-24471 (JP, B2)

Claims (3)

(57) [Claims] 1. A surface treatment method comprising a step of immersing copper and copper alloy strips in a discoloration preventing treatment solution containing an inhibitor, pulling up the strip, and then cutting off the liquid with a draining roll, an air knife or the like. A surface treatment method for copper and a copper alloy, comprising washing with pure water having an electric conductivity of 5 μS / cm or less for 2 seconds or less before a step of removing the solution from the solution. 2. The copper and copper according to claim 1, wherein the cleaning liquid is an aqueous solution obtained by adding an inhibitor for preventing discoloration of copper and a copper alloy and an auxiliary thereof to pure water having an electric conductivity of 5 μS / cm or less. Alloy surface treatment method. 3. The surface treatment method for copper and copper alloy according to claim 1, wherein the concentration of chlorine in the cleaning solution is 1 ppm or less.