JPS61281878A - Continuous coloring method for stainless steel strip - Google Patents

Abstract

PURPOSE:To color a stainless steel without uneven colors by spraying fogged water and air to the stainless steel strip right after the immersion into a coloring bath of an aq. soln. mixture composed of sulfuric acid, chromic anhydride and chromate. CONSTITUTION:The stainless steel strip 1 is passed through the coloring bath 7 of the aq. soln. mixture composed of sulfuric acid, chromic anhydride and/or chromate by immersion rolls 6 and is thereby continuously colored. The fogged water and air are sprayed by air injecting nozzles 13 and water dropping nozzles 14 to the above-mentioned stainless steel 1 emerging from the bath 7 to dilute and remove quickly the coloring liquid sticking to the steel strip 1 and at the same time to cool instantaneously the steel strip down to the temp. at which the coloring oxidation reaction does not arise. The stainless steel strip 1 is thereby continuously colored while the uneven coloration arising after the emergence from the bath 7 is prevented.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is aimed at preventing the occurrence of color unevenness that occurs after the stainless steel strip comes out of the oxidizing solution when the stainless steel strip is immersed in an oxidizing solution while being passed through to develop color. Concerning a continuous coloring method.

(Prior Art) Conventionally, stainless steel has been colored by immersing it in an oxidizing solution or molten salt bath, but the main color that can be colored has been black. For this reason, it was also used for precision optical machinery. However, there is a method in which a reference electrode is immersed together with stainless steel in a mixed aqueous solution of sulfuric acid and chromic acid, and when the potential difference between the two reaches a predetermined potential difference, the stainless steel is pulled up and colored to a desired color (VF 1973- 11
Since the development of the method (No. 243), this method has been implemented on an industrial scale.

This method makes it possible to create a colored film with better wear resistance than that produced by conventional methods, and the color tone can be reproduced with greater accuracy, making it possible to use the colored film for bathtub panels, buildings, etc. Exterior walls, roofs, etc. are conventionally expanded upward.

Coloring on an industrial scale using the above method is generally carried out in batches by immersing stainless steel cut plates in a mixed aqueous solution of sulfuric acid and chromic acid anhydride or chromate or both (hereinafter referred to as the coloring solution). However, since the productivity of the patch method is poor, recently a method has been developed in which the strip is continuously colored by immersing it in a coloring bath of a coloring liquid while passing through the strip.

Figure 141 shows an example of this continuous coloring method, in which the stainless steel strip 1 is continuously fed out from the payoff reel 2,
After degreasing and washing with water in degreasing tank 3 and washing tank 4,
Squeeze the water with the squeezing roll 5 and color it. For coloring, use the dipping roll 6 to squeeze out the water and use the coloring bath 7 containing the coloring liquid (bath temperature is usually 70-10
This is done by immersing the stainless steel strip at a temperature of 0°C), pulling it out into the air again with a squeezing roll 8, and then squeezing out the colored liquid, but the color is determined by the time the stainless steel strip is in contact with the colored liquid. The 11 ml color adjustment is carried out by changing the contact time by changing the threading speed, changing the immersion distance, etc.

After the colored stainless steel strip 1 is washed with water in a washing tank 9, the colored film is cured in a curing tank 10, and after being washed with water in a washing tank 11, it is wound onto a winding roll 12 to form a product.

(Problems to be Solved by the Invention) By the way, when stainless steel strip is continuously colored as described above, when the stainless steel 1 is pulled up from the coloring bath 7, the coloring liquid adheres to it, and the coloring liquid adheres to it. Coloring continues during this time. However, since the adhesion of the colored liquid is not uniform in the width direction of the steel strip, the areas with a small amount of adhesion are dried by the heat of the stainless steel band 1 heated by the colored liquid before the colored liquid reaches the squeezing roll 8. Chromic acid and chromate salts precipitate. Moreover, the drying and precipitation state also differs in the amount of adhesion even in areas with a small amount of adhesion, so the drying speed is different and it is not uniform. Cotton-like or cloud-like color unevenness occurs in areas with less color. Similarly, areas with a large amount of adhesion also reach the squeezing roll 8 and are marked by the squeezing roll 8, resulting in striped color unevenness in the areas where the colored liquid flows back. In particular, coloring liquid tends to accumulate at the edges of the steel strip, so color unevenness is likely to occur.

In the case of the conventional patch coloring method, it was possible to wash and cool immediately after coloring, so there were no problems such as those mentioned above, but in the case of the continuous coloring method, it was difficult to wash and cool immediately after coloring, so the color The occurrence of unevenness was inevitable.

(Means for Solving the Problems) The present invention is characterized in that when stainless steel strip is immersed in a coloring bath while passing through it and then pulled up and continuously colored, it adheres to the stainless steel #steel after coming out of the coloring bath. The coloring solution is immediately washed away and the stainless steel strip is cooled to prevent color unevenness from occurring.The coloring solution is immediately washed away and the stainless steel strip is sprayed with atomized water and air onto the stainless steel strip that has come out of the coloring bath. This is what I decided to do.

In the present invention, atomized water and air are sprayed because it is necessary to instantaneously dilute and remove the attached colored liquid and cool it in order to prevent color unevenness.

For example, when using only atomized water, the degree of dilution and cooling is small in areas where a large amount of colored liquid adheres, and the colored liquid remains attached to the steel strip, so that the coloring oxidation reaction is further accelerated. On the other hand, if only air is used, it is difficult to completely remove the colored liquid unless the pressure is increased, and if the pressure is increased, the dangerous colored liquid will scatter, making it dangerous for work. On the other hand, if you spray both atomized water and air, the air will first remove the colored liquid before dilution.
Next, water is supplied to the area where the amount of attached colored liquid is reduced to dilute and remove it, so that the attached colored liquid becomes extremely thin in concentration.

Moreover, since the steel strip is cooled not only by water and air but also by the heat of vaporization of water, the steel strip is instantaneously cooled to a temperature at which coloring and oxidation reactions do not occur.

Note that instead of atomized water and air, it may be possible to clean and cool with just regular water that is not atomized, but if you spray regular water, the cleaning and cooling water will flow into the coloring bath, causing the coloring to occur. This is not preferable because the color may change due to fluctuations in the concentration and temperature of the colored liquid in the bath.

In the case of the present invention, since the water is atomized, the amount of washing and cooling water flowing into the coloring bath is small, and is approximately equal to the amount of evaporation when the temperature is 80°C or higher, which is the normal working temperature of the coloring bath. or lower, so there is no fluctuation in the concentration or temperature of the colored liquid.

However, if the amount of cleaning and cooling water flowing into the coloring bath is greater than the amount of evaporation, and the concentration and temperature of the coloring liquid decreases, the cleaning and cooling water is collected in a tray, concentrated, and reused. It may be returned to the coloring bath.

The spraying of atomized water and air may be carried out by atomizing water with air, or may be carried out by electromagnetic force as in the case of an airless gun.

Next, the present invention will be explained with reference to examples.

(Example) Fig. 2 shows a method of coloring stainless steel strip 1 according to the present invention, in which a dipping roll 6 and a squeezing roll 8 in a coloring bath 7 are shown.
An air injection nozzle 13 and a water dripping nozzle 14 are arranged on both sides of the stainless steel strip threading position between the two, and water is dropped from the latter into the air injected from the former to form a mist. Spray on both sides of stainless steel strip 1. As a result, the adhered colored liquid is washed and the stainless steel strip 1 is also cooled, so that uneven coloring does not occur.The amount of air to be injected and the amount of water to be dripped are adjusted by valves 15 and 16.

A receiver plate 17 is arranged below the nozzle to receive the washing and cooling water, and after concentrating it in the concentration step 8!18, it is transferred to the coloring bath 7.
Return to

Next, an example will be shown in which stainless steel strip 1 is continuously colored using this method.

(1) As the coloring bath 7, a coloring liquid containing sulfuric acid 5009i, chromic anhydride 2509/e and a temperature of 85°C is used.
US304, B^ finish stainless steel strip 1 (plate width 300
am) was immersed while passing the plate at a speed of 1.5 m+/min to color it.

1 from the air injection nozzle 13 when it comes out into the air after coloring.
．． While blowing air at a rate of 5 Kg/am', water was dropped from the water dropping nozzle 14 at a rate of 30 ml/liter, thereby spraying the water into a mist. Although the distance between the dipping roll 6 and the squeezing roll 8 was 1.2 wheels, no color unevenness occurred and the whole was colored in a uniform golden color.

On the other hand, when I closed the valves 15 and 16, stopped air injection and water dripping from the air injection nozzle 13 and water dripping nozzle 14, and tried coloring at the same sheet threading speed, I found light red striped unevenness due to the attached colored liquid. Occurred.

(2) Stainless steel strip 1 (width 200 mm) with S[l5304, IIL finish] was passed through a coloring bath having the same composition as in (1) above and whose temperature was raised to 95°C at a rate of 3.0 tons per plate. s
The plate was immersed while passing through the plate, and colored for 1 hour continuously.

The spraying of air from the air injection nozzle 13 and the dripping of water from the water dripping nozzle 14 after coloring are carried out under the same conditions as in (1) above, with the tray 17 removed. The entire amount of washing and cooling water was made to be in the coloring bath 7.

As a result, the stainless steel strip 1 was colored blue with no color unevenness, the liquid level of the coloring bath 7 was lowered, and the amount of evaporation was greater than the inflow of cleaning and cooling water.

When this was colored by spraying air from the air injection nozzle 13 and stopping dripping of water from the water dripping nozzle 14, pale yellow striped color unevenness occurred.

(Effects) As described above, the present invention cleans the attached colored liquid after coloring, which conventionally caused color unevenness, and cools the stainless steel strip, so that color unevenness does not occur.

In addition, since the adhering colored liquid is washed and the stainless steel strip is cooled by spraying n-shaped water and air, the colored liquid will not be taken out of the coloring bath, and the concentration and temperature of the coloring bath will fluctuate. Never.

[Brief explanation of the drawing]

Figure 1 shows colored lines by the conventional coloring method, and the second
The figure shows an embodiment of an apparatus for carrying out the coloring method of the present invention. 1... Stainless steel strip, 2... Payoff reel, 3
... Degreasing tank, 4... Washing tank, 5... Squeezing roll,
6... Dipping roll, 7... Coloring bath, 8... Squeezing roll, 9... Washing tank, 10... Curing tank, 11...
Washing tank, 12... Take-up reel, 13... Air injection nozzle, 14... Water I lower nozzle, 15... Valve, 16
... Valve, 17... Receiver is plate, 18... Concentrator,

Claims (1)

[Claims] In a method of continuously coloring stainless steel strip by immersing it in a coloring bath of a mixed aqueous solution of sulfuric acid and chromic anhydride or chromate or both while passing through the steel, a mist is applied to the stainless steel strip coming out of the coloring bath. A continuous coloring method for stainless steel strip, characterized by spraying, cleaning, and cooling with water and air.