JPH0931840A - Pre-dyeing bleaching method and apparatus - Google Patents

Abstract

(57) [Abstract] [Problem] When bleaching a cloth in the previous step of dyeing,
The effect of the cleaning wastewater 11 on the environment due to the use of a chlorine-based oxidizing agent as a bleaching agent is effectively suppressed with simple equipment. SOLUTION: The cloth 1 before dyeing has a moisture content of 20% or more 100
% Or less, and the ozone-containing gas is brought into contact with the cloth to be bleached, and the acid generated as a result of the bleaching is washed. In addition, a swelling tank 4 that absorbs and swells the cloth 1 before dyeing to a moisture content of 20% or more and 100% or less, an ozone generator 7 that generates ozone-containing gas, and a cloth that is absorbed and swelled by the swelling tank 4 Ozone bleaching tank 6 for bleaching by contacting ozone-containing gas generated by the ozone generator 7
And a cleaning tank 9 for cleaning the acid generated as a result of the bleaching in the ozone bleaching tank 6 from the cloth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bleaching method and a bleaching apparatus for cloth in a pre-dyeing step of a dyeing factory, and more particularly to a bleaching method and a bleaching apparatus for bleaching cloth without using a chlorine bleaching agent.

[0002]

2. Description of the Related Art Generally, in a piece of cloth produced by a spinning machine or a fiber machine, a surface active agent or glue used for warp threads is attached to the fiber. Furthermore, since the untreated coloring component lignin remains inside the fiber, the entire cloth has a light brown color. Therefore, in order to beautifully dye this fabric in any color, it is necessary to bleach the fabric before the dyeing process. Prior to this bleaching, the steps of desizing and scouring are carried out.

Therefore, in the bleaching and dyeing processes of cloths in a dyeing factory, chemical agents such as oxidants, chlorine-based sodium hypochlorite, dyes and the like are used as bleaching agents in high concentration and in large amounts. Furthermore, since each cleaning step is required, a large amount of this chemical is used, and accordingly a large amount of waste water is generated.

A dyeing process performed in such a dyeing factory is constructed as shown in FIG. 4, for example. The raw cloth 1 supplied from the reel is subjected to the de-soldering step 2 to remove the paste adhered to the raw cloth 1 and then to the next scouring step 3 to obtain the raw cloth 1
Impurities are removed. The scoured cloth absorbs and swells the oxidizing agent in the chlorine-based oxidizing agent solution tank 4A, and the bleaching reaction is performed in the reaction tank 4B. The bleached cloth is then washed with water 10
Is guided to the cleaning tank 9 in which is stored. In this cleaning tank 9, the organic acid generated as a result of bleaching, the organic halogen compound and the excess absorbed unreacted chlorine-based oxidizing agent are washed off from the cloth. The dirty cleaning water 10 is separately transferred as cleaning drainage 11 to a water treatment facility for treatment / discharge.

Since the cleaning waste water 11 contains harmful by-product and unreacted chlorine-based oxidizing agent, biological treatment is impossible. The washed cloth is squeezed and dried.
Dyeing step 13. After the post-processing step 14 and the finishing step 15, the product cloth 16 is wound on a reel.

[0006]

However, the bleaching apparatus incorporated in the dyeing process shown in FIG. 4 still has the following problems to be solved. In other words, in recent years, regulations on the environment of factories have become stricter, and it has become necessary to shift to a water-saving bleaching / dying method and consider the quality of drainage water. In particular, when chlorine-based agents are used in high concentration and in large amounts in the bleaching process, surfactants, organic substances such as glue, etc. remaining after the desizing and scouring process and organohalogen compounds generated by reaction with the cloth itself cause carcinogenesis. And mutagenicity become water environment problems in the discharged water area.

[0007] Further, these compounds are not subject to microbial decomposition and are accumulated and concentrated in the environment and in the living body, so that they are regulated by the entire regional environment. As the scale of the dyeing factory increases, the facilities for eliminating these environmental impacts become enormous, and the cost for the facilities increases significantly.

The present invention has been made in view of such circumstances, and by using ozone, the cloth can be efficiently bleached without using a chlorine-based oxidizing agent that produces an organic halogen compound, and the ambient environment can be improved. Dyeing pretreatment process that can prevent the inclusion of organohalogen compounds in the discharged wastewater, simplify the water treatment process of the wastewater, simplify the entire equipment, and significantly reduce the maintenance cost of the equipment. An object of the present invention is to provide a bleaching method and a bleaching apparatus in

[0009]

In order to solve the above-mentioned problems, in the bleaching method in the pre-dyeing step according to claim 1, the cloth before dyeing is made to absorb and swell to a moisture content of 20% or more and 100% or less, Ozone-containing gas is brought into contact with the hygroscopic and swollen cloth for bleaching, and the acid generated as a result of the bleaching is washed.

In the bleaching method of claim 2, the cloth before dyeing in the bleaching method of claim 1 is impregnated with water or an aqueous solution whose pH is adjusted to 5 or less with an organic acid so that the cloth has a moisture content of 20%. The moisture is absorbed and swelled to 100% or less.

Further, in the bleaching method of claim 3,
In the bleaching method according to claim 1 or 2, the cloth after being brought into contact with the ozone-containing gas is heated to 50 ° C or lower and then washed.

Further, in the bleaching method of claim 4,
In the bleaching method according to claim 1 or 2, the cloth after being brought into contact with the ozone-containing gas is irradiated with ultraviolet rays and then washed.

In the bleaching apparatus in the pre-dyeing treatment step according to claim 5, the cloth before dyeing has a moisture content of 20% or more and 10% or more.
Bleaching by contacting the swelling tank that absorbs and swells to 0% or less, the ozone generator that generates ozone-containing gas, and the ozone-containing gas that is generated by the ozone generator to the cloth that has absorbed and swelled in the swelling tank The ozone bleaching tank and the washing tank for washing the cloth from the acid generated as a result of the bleaching in the ozone bleaching tank.

Further, the bleaching apparatus of claim 6 is a method for absorbing and swelling the cloth in the bleaching apparatus of claim 5 to a moisture content of 20% or more and 100% or less.
An aqueous solution adjusted to H5 or less is impregnated.

Further, the bleaching apparatus of claim 7 is the bleaching apparatus of claim 6.
In the bleaching apparatus, the heating device for heating the cloth after contacting the ozone-containing gas in the ozone bleaching tank to 50 ° C. or less is interposed between the ozone bleaching tank and the cleaning tank.

The bleaching apparatus according to claim 8 is an ultraviolet ray for irradiating the cloth after contacting an ozone-containing gas in the ozone bleaching tank with an ultraviolet ray between the ozone bleaching tank and the washing tank in the bleaching apparatus according to claim 6. The irradiation device is interposed.

According to the bleaching method and the bleaching apparatus in the pre-dyeing step thus constituted, ozone contained in the ozone-containing gas diffuses inside the fibers of the hygroscopically swollen cloth and remains in the fibers. Bleaching is completed by reacting with the coloring component lignin. As a result, aldehydes, kents, carboxylic acids and the like, which are easily decomposed by microorganisms, are produced as reaction by-products.

In general, ozone has a strong oxidizing power and disappears due to self-decomposition of ozone itself, but the self-decomposition of ozone itself is accelerated by a rise in ambient temperature and irradiation with ultraviolet rays. Further, ozone in a solution has a faster self-decomposition rate than gaseous ozone, and this decomposition rate depends on the pH of the solution. That is, it is relatively stable at pH 5 or lower,
In the alkaline region, autolysis proceeds rapidly.

Ozone-containing gas has been widely used as a process for purifying safe drinking water, and it can be easily taken into oxygen at a desired concentration by taking in oxygen or oxygen cylinders in the atmosphere.

As a result of various experiments in consideration of such known characteristics of ozone, the inventor has found that it is important to effectively diffuse and reach ozone inside the fiber when oxidizing lignin inside the fiber. It was demonstrated that the cloth is effectively bleached under the optimum conditions that promote the oxidation reaction inside the fiber after diffusion.

Therefore, in the present invention, the cloth is previously made to absorb and swell to a moisture content of 20% or more and 100% or less. Therefore, unlike the conventional bleaching method, the cloth can be efficiently bleached without using a chlorine-based oxidizing agent, so that harmful substances are not contained in the wastewater and the amount of washing wastewater is reduced. As a result, the water treatment of the waste water is simplified and can be decomposed by using microorganisms.

In the second and sixth to eighth aspects, in addition to the above-mentioned conditions, a pH of 5 is obtained with water or an organic acid.
The bleaching effect is further improved by absorbing and swelling the cloth with the following aqueous solution.

Further, by raising the temperature of the cloth after being brought into contact with the ozone-containing gas or irradiating the cloth after being brought into contact with the ozone-containing gas with ultraviolet rays, the self-decomposition of ozone is promoted, and the ozone is decomposed in a shorter time. It has been proved that the desired bleaching effect can be obtained.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Each embodiment of the present invention will be described below. Before the description of each embodiment, an experiment conducted by the inventor will be described. A cotton cloth that has undergone the desizing and scouring steps is used as the test cloth, and the test cloth is subjected to standard bleaching using sodium hypochlorite and ozone bleaching using ozone-containing gas. Then, the whiteness of each test object cloth after bleaching was compared.

The bleaching tank has a width of 0.2 m. Prepare an acrylic airtight box with a height of 0.1 m and a length of 0.5 m,
In each of the bleaching tanks, each cloth to be tested whose water content was adjusted was dipped. In the ozone bleaching treatment, the moisture content of the test fabric is adjusted to the pH value in consideration of the purpose of suppressing the self-decomposition of ozone and the fact that the washing and wastewater treatment after bleaching can be performed by a standard biological treatment method.
It adjusted with the acetic acid aqueous solution of 5. In addition, the ozone-containing gas obtained by an ozone generator using oxygen as a raw material gas is contacted with the ozone-containing gas evenly on the front and back of the sample cloth after adjusting the aeration temperature in pure water to keep the moisture content of the cloth constant. Thus, the bleaching tank was continuously supplied at a flow rate of 0.42 l / min.

The whiteness is the same for the same test cloth.
The reflectance of light having a wavelength of 466 nm in a spectrophotometer was measured at three points on the cloth surface, and an average value was obtained. The experimental conditions and experimental results are shown below.

[Experimental conditions of standard method (conventional method)] Bleaching tank 0.2 x 0,1 x 0,5 m ³ Effective chlorine 3 g / l (pH 11.5) Penetrant 0.1 to 0.2% Treatment condition 20 ° C 4hr [Experimental conditions for ozone bleaching method] Bleaching tank Same as above Source gas Oxygen ozone concentration 30 g / Nm ³ Treatment conditions 20 ℃ 30min pH5 Moisture content 5,15,20,40,100%

[0028]

[Table 1]

When the whiteness of the standard method using the ordinary chlorine-based bleaching agent obtained in this experimental result and each whiteness in the ozone bleaching method are compared, each whiteness obtained by the ozone bleaching method is It was carried out that it was comparable to the standard method. Particularly, when the water content is 20% or more and 100% or less, the bleaching effect is excellent.

Further, the time required for obtaining the same whiteness is significantly shortened in the ozone bleaching method as compared with the standard method. The reason why the whiteness is slightly lowered at a water content of 40% is that the self-decomposition of ozone in free water cannot be ignored even if the free water between fibers has a pH of 5 which is stable against the self-decomposition of ozone. I think.

(First Embodiment) FIG. 1 shows a dyeing process in which the bleaching apparatus of the first embodiment in which each condition in the experimental result is taken into consideration is incorporated.

The same parts as those in the dyeing process in which the conventional bleaching apparatus shown in FIG. 4 is incorporated are designated by the same reference numerals. Therefore, detailed description of the overlapping portions is omitted.
The raw cloth 1 supplied from the reel is scoured in the next scouring step 3 after removing the adhered glue in the gluing step 2. The refined cloth 1 is guided into the expansion tank 4. The expansion tank 4 contains water adjusted to pH 5 or an acetic acid aqueous solution. It may be an aqueous acetic acid solution having a pH of 5 or less.

In the expansion tank 4, the cloth 1 is absorbed and swelled by an acetic acid aqueous solution adjusted to pH 5, and the water content is 20 to 1 by the next roll squeezing air jet 5.
It is adjusted to 00%.

The cloth whose moisture content is adjusted to 20 to 100% is introduced to the next ozone bleaching tank 6. In the ozone bleaching tank 6,
The ozone generator 7 is connected. Ozone generator 7
Takes in oxygen from the atmosphere or a separately prepared oxygen cylinder to generate ozone, and ozone-containing gas is discharged into the ozone bleaching tank 6
And ozone-containing gas is effectively diffused in the ozone bleaching tank 6. In addition, the gas concentration of ozone contained in the ozone-containing gas can be electrically and easily controlled in the ozone generator 7. The cloth guided to the ozone bleaching tank 6 is bleached with the ozone-containing gas according to the principle described above.

The unreacted ozone in the ozone bleaching tank 6 is decomposed by the exhaust ozone decomposer 8 and released into the atmosphere. The cloth bleached in the ozone bleaching tank 6 is introduced into the next cleaning tank 9. Cleaning water 10 is stored in the cleaning tank 9. Organic acids such as glyoxylic acid and oxalic acid generated as a result of bleaching in the ozone bleaching tank 6 and excess absorbed acetic acid are washed off from the cloth with the cleaning water 10 contained in the cleaning tank 9.

The soiled cleaning water 10 after cleaning a cloth of a predetermined length is separately transferred to a water treatment facility as cleaning drainage 11 and treated / discharged. Since the cleaning wastewater 11 does not contain harmful by-products or unreacted chlorine-based oxidizing agent, general biological treatment is possible.

The washed cloth is squeezed and dried 12,
After a dyeing process 13, a post-treatment process 14 and a finishing process 15, a product cloth 16 is wound on a reel. In the bleaching apparatus in the dyeing pretreatment step configured in this way,
The ozone bleaching method is used. As described above, the cleaning wastewater 11 does not contain harmful by-products and unreacted chlorine-based oxidizers, and therefore can be subjected to general biological treatment. That is, the treatment facility for the cleaning wastewater 11 is simplified, and the facility cost can be significantly reduced. Further, the influence on the water environment can be minimized.

Further, by adopting the ozone bleaching method, the amount of cleaning wastewater 11 itself can be reduced. Also,
The bleaching time can be shortened compared to the standard method using a chlorine bleaching agent. Therefore, when the product cloth 16 is obtained from the original cloth 1 at the same line speed, the time for immersing the cloth in the bleaching tank is short. Therefore, the size of the bleaching tank can be compared with the standard method, and the length of the cloth in the bleaching tank in the conveying direction can be shortened. Therefore, the entire dyeing pretreatment process can be downsized.

Further, the ozone generator 7 can easily and inexpensively produce an ozone-containing gas having an arbitrary gas concentration by using oxygen in the atmosphere or an oxygen cylinder or by electrolysis of water. Therefore, the running cost of the dyeing process can be further reduced.

It should be noted that the diffusion of ozone into the fiber depends on the concentration, and it is considered that the higher the ozone concentration is, the more effectively the bleaching can be performed, but the ozone concentration can be freely controlled in consideration of the generation efficiency. , This ozone bleaching method
It is advantageous compared to the standard method using the conventional chlorine bleach.

Next, the results of experiments conducted on the effect of temperature during ozone bleaching will be described. An ozone bleaching experiment was carried out under the following experimental conditions by using the test target cloth and the bleaching tank when the moisture content was changed as described above. And the experimental result of the whiteness shown in Table 2 was obtained.

[Experimental conditions of ozone bleaching method] Source gas Air Ozone concentration 20 g / Nm ³ Treatment condition 30 min pH3, Moisture content 60% Temperature 20, 50.80 ° C

[0043]

[Table 2]

The contact time with the ozone-containing gas was set to 30 minutes, and after the contact, the cloth to be tested was taken out promptly, and the cloth to be tested was sandwiched between the metal plates having the corrosion resistance controlled to the above-mentioned temperature conditions. After being left for a minute, the whiteness was defined by the method described above.

As shown in the experimental results, it can be understood that the bleaching effect is better when the temperature is set to 60 ° C. and 80 ° C. than when the temperature is set to 20 ° C. This is considered to be because the self-decomposition of ozone diffused inside the fiber by heating was promoted and a good bleaching effect was obtained in a short time.

When the heating temperatures of 50 ° C. and 80 ° C. are compared, it can be understood that the bleaching efficiency is almost at the same level, but the heating temperature of 50 ° C. is sufficient considering the operating cost of the entire equipment.

(Second Embodiment) FIG. 2 shows a dyeing process in which the bleaching apparatus of the second embodiment, in which the conditions of heating temperature in the experimental result are taken into consideration, is incorporated.

The same parts as those in the dyeing step in which the bleaching apparatus of the first embodiment shown in FIG. 1 is incorporated are designated by the same reference numerals. Therefore, detailed description of the overlapping portions is omitted.

In this dyeing process, the ozone bleaching tank 6
A heating roller 6A having a heater housed therein is interposed as a heating device between the cleaning tank 9 and the cleaning tank 9. The heating roller 6A is controlled to a constant temperature near 50 ° C. and not exceeding 50 ° C.

In the dyeing process thus constructed, the cloth brought into contact with the azo-containing gas in the ozone bleaching tank 6 is heated to about 50 ° C. by the heating roller 6A. As a result, ozone diffused into the fibers of the cloth is self-decomposed by rapid heating and becomes an oxygen radical with strong oxidizing power. It becomes a hydroxyl radical and oxidizes and decolorizes lignin, which is a coloring substance.

Although the heating roller 6A is used as the heating device in the apparatus of the second embodiment, it may be a heating device using microwaves, infrared rays, or the like. In the bleaching device in the dyeing process configured in this way,
Since the heating roller 6A is used as the heating device, a desired bleaching efficiency can be obtained in a shorter time as compared with the bleaching device of the first embodiment shown in FIG.

Next, the results of experiments conducted on the influence of ultraviolet irradiation during ozone bleaching will be described. An ozone bleaching experiment was carried out under the following experimental conditions using the test target cloth and the bleaching tank when the moisture content was changed. And the experimental result of the whiteness shown in Table 3 was obtained.

[Experimental conditions of ozone bleaching method] Source gas Air Ozone concentration 20 g / Nm ³ Treatment conditions 20 ° C., 30 min, pH 3, moisture content 60% UV irradiation time 10 min, 20 min

[0054]

[Table 3]

Specifically, the ozone-containing gas was brought into contact with the experimental fabric stored in the bleaching tank for 30 minutes, and then,
The supply of ozone-containing gas was stopped, and two 15W low-pressure mercury lamps for sterilization, which were attached to the upper part of the bleaching tank, were placed from the position 2 cm above the test cloth to the test cloth for 10 minutes and 2
Irradiated for 0 minutes. Then, each whiteness was measured by the method described above.

In the case of ultraviolet irradiation, there is a large absorption line of ozone at a wavelength of 260 nm, and the self-decomposition of ozone is promoted in gas, liquid, and fiber, and oxygen radicals with strong oxidizing power, similar to the case of heating, It becomes a hydroxyl radical. for that reason,
The ozone diffused inside the fiber was promoted to self-decompose by irradiation of ultraviolet rays, and a good bleaching effect was obtained in a short time.

(Third Embodiment) FIG. 3 shows a dyeing process in which the bleaching apparatus of the third embodiment in which the conditions of ultraviolet irradiation in the above experimental results are taken into consideration is incorporated.

The same parts as those in the dyeing process in which the bleaching apparatus of the first embodiment shown in FIG. 1 is incorporated are designated by the same reference numerals. Therefore, detailed description of the overlapping portions is omitted.

In this dyeing example step, an ultraviolet irradiation device 6B having a plurality of ultraviolet lamps incorporated therein is interposed between the ozone bleaching tank 6 and the cleaning tank 9. The length of the ultraviolet irradiation device 6B in the carrying direction and the number of lamps are set so that the time required for each point of the cloth to pass through the ultraviolet irradiation device 6B is, for example, 10 minutes.

In the dyeing process thus constructed, the cloth which is brought into contact with the Ozo-containing gas in the ozone bleaching tank 6 is
The ultraviolet irradiation device 6B receives ultraviolet irradiation at intervals of 10 minutes. As a result, the ozone that has diffused into the fibers of the cloth is self-decomposed by ultraviolet rays and becomes an oxygen radical with strong oxidizing power. It becomes a hydroxyl radical and oxidizes and decolorizes lignin, which is a coloring substance.

Further, in the bleaching apparatus of the third embodiment in the dyeing process thus constructed, since the ultraviolet irradiation apparatus 6A is used, the first and second embodiments shown in FIGS. 1 and 2 are used. It is possible to obtain a desired bleaching efficiency in a shorter period of time as compared with the bleaching apparatus in the above.

[0062]

As described above, in the bleaching method and the bleaching apparatus in the pre-dyeing process of the present invention, after the cloth is absorbed and swollen to shift to the optimum state for bleaching,
The fabric is bleached with ozone. In addition, the chlorine-based oxidant that generates the organic halgen compound, which is required in the conventional bleaching method, is not used.

Therefore, the cloth can be bleached efficiently and in a short time, and the wastewater discharged to the environment can be prevented from containing an organic halogen compound, and the wastewater treatment process can be simplified by using, for example, microorganisms. Therefore, the entire equipment can be simplified, and the maintenance cost of the equipment can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a dyeing process in which a bleaching device adopting a bleaching method according to a first embodiment of the present invention is incorporated.

FIG. 2 is a schematic diagram showing a dyeing process in which a bleaching apparatus adopting the bleaching method of the second embodiment of the present invention is incorporated.

FIG. 3 is a schematic diagram showing a dyeing process in which a bleaching apparatus adopting the bleaching method of the third embodiment of the present invention is incorporated.

FIG. 4 is a schematic diagram showing a dyeing process in which a conventional bleaching device is incorporated.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Original cloth, 2 ... Desaling process, 3 ... Refining process, 4 ... Expansion tank, 5 ... Roll squeezing and air jet spraying, 6 ... Ozone bleaching tank, 6A ... Heating roller, 6B ... Ultraviolet irradiation device, 7
... ozone generator, 8 ... waste ozone decomposing device, 9 ... cleaning tank, 10 ... cleaning water, 11 ... cleaning drainage, 12 ... squeezing and drying step, 13 ... dyeing step, 14 ... post-treatment step, 15 ...
Finishing process, 16 ... Product cloth

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Yuzuru Sato No.1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Fuchu factory, Toshiba Corp. (72) Inventor, Masao Takahashi 4-29-2 Nanri Gahamahi, Kamakura-shi, Kanagawa

Claims (8)

[Claims] 1. A cloth before dyeing has a moisture content of 20% or more and 100% or more.
A bleaching method in a pre-dyeing step, which is characterized in that the cloth is made to absorb and swell, and the cloth thus made to absorb and swell is brought into contact with an ozone-containing gas to bleach, and an acid generated as a result of the bleaching is washed. 2. The cloth before dyeing is applied with water or an organic acid.
By impregnating with an aqueous solution adjusted to H5 or less,
The bleaching method in the dyeing pretreatment step according to claim 1, wherein the cloth is made to absorb moisture and swell at a moisture content of 20% or more and 100% or less. 3. The bleaching method in the dyeing pretreatment step according to claim 1, wherein the cloth after being brought into contact with the ozone-containing gas is heated to 50 ° C. or lower and then washed. 4. The bleaching method in the dyeing pretreatment step according to claim 1 or 2, wherein the cloth after being brought into contact with the ozone-containing gas is irradiated with ultraviolet rays and then washed. 5. The moisture content of the undyed cloth is 20% or more and 100%.
Bleaching by contacting the ozone-containing gas generated by the ozone generator with a swelling tank for absorbing and swelling the following, an ozone generator for generating an ozone-containing gas, and a cloth absorbed and swollen by the swelling tank A bleaching device in a pre-dyeing process, comprising: an ozone bleaching tank for cleaning and a cleaning tank for cleaning an acid generated as a result of bleaching in the ozone bleaching tank from a cloth. 6. A swelling tank which absorbs and swells the cloth to a moisture content of 20% or more and 100% or less by impregnating the cloth before dyeing with an aqueous solution adjusted to a pH of 5 or less with an organic acid,
An ozone generator for generating an ozone-containing gas, an ozone bleaching tank for bleaching by bringing the ozone-containing gas generated by the ozone generator into contact with the cloth absorbed and swollen in the swelling tank, and this ozone bleaching tank And a washing tank for washing the acid generated as a result of the bleaching from the cloth, in the pre-dyeing treatment step. 7. A swelling tank which absorbs and swells the cloth to a moisture content of 20% or more and 100% or less by impregnating the cloth before dyeing with an aqueous solution adjusted to a pH of 5 or less with an organic acid,
An ozone generator for generating an ozone-containing gas, an ozone bleaching tank for bleaching by bringing the ozone-containing gas generated by the ozone generator into contact with the cloth absorbed and swollen in the swelling tank, and this ozone bleaching tank A heating device for heating the cloth after contacting the ozone-containing gas with 50 ° C. or less, and a cleaning tank for cleaning the acid generated as a result of the bleaching from the cloth heated by the heating device. A bleaching device in a dyeing pretreatment step, which is characterized in that 8. A swelling tank which absorbs and swells the cloth before dyeing with an aqueous solution whose pH is adjusted to 5 or less with an organic acid to absorb and swell the cloth to a moisture content of 20% or more and 100% or less,
An ozone generator for generating an ozone-containing gas, an ozone bleaching tank for bleaching by bringing the ozone-containing gas generated by the ozone generator into contact with the cloth absorbed and swollen in the swelling tank, and this ozone bleaching tank And a cleaning tank for cleaning the acid produced as a result of the bleaching from the cloth irradiated with ultraviolet rays by the ultraviolet irradiation apparatus. Bleaching equipment in the pre-dyeing process.