Technical Field The invention generally is related to a method regarding the indigo paint being absorbed by the fabric in the textile sector.

The invention specifically is related to a method regarding the dye in leuco indigo form being oxidized and performing the painting of the fent in a closed area, without needing to be in contact with air.

State of the Art

Today, one of the paint types that are used in the textile sector is indigo paint. The indigo is an azo dye and does not dissolve in water. In order for the indigo dye to be absorbed by the fabric, it shall primarily be exposed to a reduction reaction and it penetrates to the yarn, then it shall be fixed by being oxidized.

The indigo dyeing process in the prior art is being performed by using warp dyeing machines (Slasher Dyeing, Rope Dyeing) in textile mills. Normally, this process is performed in machines with sizes of a range 90 to 100 meters and in 450 - 500 m warp length. The yarn is being pressed into the tanks which include leuco indigo dye, of which the reduction reaction is performed by auxiliary chemicals, with 25 m / minute dosage. The yarn is being dyed in yellow-green color into the leuco indigo form when it goes through these tanks and it is wrung by cylinders afterwards. After this step, the indigo dye is oxidized as a result of being in contact with air and this results in that the said yellow green color (leuco) turns into blue and the dyeing step is completed. This dyeing process continues with the yarn going through the warping machine. Factors such as the number of tanks, the dyeing percentage, the oxidation degree, the pressure of wring and the yarn tension etc. can be altered when the dyeing is performed, depending on the intensity of the desired color. In the prior art, the indigo dyeing process cannot be performed in closed systems without being in contact with the air, in fent dyeing establishments.

In the literature, an application with number CN105401463 and title “Deep dyeing method in one step for raw cotton using indigo dye” and another application with number TW201350639 and the title“A method for dyeing indigo blue and cloth textile processing”; several implementations regarding the indigo dye in the leuco form to be absorbed better by the fabric, due to an improved reduction reaction in which chemical agents are used, are described. However in these examples, the step in which the indigo dye in leuco form being oxidized and being fixed into the fabric, oxidation in other words, is performed by air contact. Therefore, these developments are also not appropriate for dyeing of fents where closed machines are used.

As a result, developments are needed in the method of indigo dyeing in the textile sector and therefore novel structurings, which shall eliminate all the disadvantages mentioned above and also provide a solution to the existing systems, are required.

Aim of the Invention

The present invention is related to a indigo dyeing method to be used for textile products that are developed to be used in the textile sector, which eliminates all the disadvantages and provides some additional advantages. Main aim of the invention is to develop a method that enables the yarn to be dyed with indigo dye without needing to be in contact with air.

One aim of the invention is to develop a method that enables the indigo dyeing being performed in closed systems in which the air contact is not possible, to be used in fent dyeing establishments. In order to realize all the advantages mentioned above and understood from the detailed description below, the present invention is a method which is developed for the indigo dye to be used for dyeing of the fents in closed systems, wherein it includes the steps of: i. preliminary scouring of the fents by at least one indigo fixator and a wetting agent, ii. preparing the dye solution,

iii. dyeing the fents which are exposed to the preliminary scouring with the prepared dye solution,

iv. rinsing the dyed fents,

v. oxidation of the rinsed fents with at least one oxidation chemical in a closed area, vi. rinsing the fents which are indigo dyed,

vii. fixing the rinsed fents with at least one indigo fixator

viii. wringing and drying.

The structural and characteristical properties of the invention, along with its all advantages, shall be understood in a clear manner by the detailed description below; therefore; an evaluation shall be made by taking the detailed description into the account.

Detailed Description of the Invention

In this detailed description, the indigo dyeing method of the invention and its preferred structurings are being merely explained in order for the issue to be understood in detail in a non-limiting manner.

The method of the invention provides an indigo dyeing process in closed systems generally in the fent dyeing establishments. In closed systems, the dyeing process is performed by exposing the fent to the indigo dye by using special wetting agents and by using oxidation chemicals, which are developed for the method, in a new tub. In the first tub, the fents which are dyed green with the leuco indigo form, which is yellow, turn to blue by the chemicals in the water, that enable the fents to undergo an oxidation reaction, and the dyeing is completed.

In the first step of the method of the invention, a preliminary scouring step is performed in order to clean the fent. In this step, the fents are washed in a washing machine at 20 - 25 Ό degrees for 5 minutes. Here, in order for t he fents to be washed and keep the dye after the process, 2 g/l of indigo fixator and 1 g/l of wetting agent are used. The indigo fixator enables the indigo dye to attach to the fabric in a better manner and eliminates the backwards dyeing in the next tubs and increases the rubbing fastness after the dyeing process. The wetting agent which is used in this process step decreases the surface tension of the water and enables the dye to be absorbed by the fabric in the dyeing step, due to its special content. Therefore, during the dyeing process, color and accuracy of dyeing increase.

After the preliminary scouring process, fents are taken into the dyeing tub for the dyeing process, which is the second step, without performing rinsing. Here, in order to reduce the indigo dye, hydrosulphite and caustic are used. In addition, the caustic is used to provide the alkali medium that is desired for the dyeing procedure. In this step, in order to enable the fabric being wet more rapidly and to increase the absorption of the dye by the fabric, the wetting agent, that is developed for the method and used in the previous step, is used again. In addition to that, in order to manage the hardness of the water in the dyeing step, ion immobilizer is used. The ion immobilizer also forms complex with the metal ions during the dyeing step and prevents these being precipitated onto the fabric and increases the accuracy of dyeing by keeping the dye which is not fixed to the fabric suspended in tub due to its dispensation property.

Before starting the dyeing procedure, the dye solution shall be prepared in a different container. In order to prepare the solution, ion immobilizer, wetting agent, caustic, indigo dye and lastly hydrosulphite are added into the water in this respective order, the solution is stirred or 30 minutes and it is left to rest for 30 minutes. Later, this solution is added to the tub when the fent is inside the machine. The weight of water is calculated as ten liters of water per one kilogram of fent, depending on the weight of the fent. On the other hand, the amount of dye is calculated as (the weight of the fent) x (the dyeing percentage) x 10, depending on the dyeing percentage and the weight of the fent. After calculating the amount of dye to be used, the amounts of hydrosulphite, caustic, wetting agent and ion immobilizer are calculated by the recipe that is previously determined and the solution is prepared accordingly as it is described above. After the solution is prepared, the dyeing process starts and it lasts for an hour at 20 - 25 °C degrees. Upon the completion of the dyeing process, rinsing in cold water is performed for one minute.

After the rinsing step, the oxidation step shall be performed, which is the most important process step of the indigo fent dyeing method in closed systems of the invention. The purpose of this step is to turn the indigo dye in the leuco form with yellow-green color, which is enabled to be absorbed by the yarn by being degraded in the dyeing step, into blue color by the oxidation reaction and to fix it to the yarn. For this, the tub is filled with water and 1 g/l of oxidation chemical after the rinsing step. The said oxidation chemical, which is developed to enable the oxidation of the fents in closed systems, increases the amount of oxygen in the tub (by extracting the oxygen in the water) and it enables the oxidation reaction to be performed. For this, the respective flotte is filled with water after the rinsing, 1 g/l of oxidation chemical is added and it is operated for 5 minutes.

Therefore, the yellow-green dye in leuco form, which has been absorbed by the fabric, turns into indigo blue as a result of the oxidation of the dye. Here, Dng Blue Vodoo® oxidation chemical is used. After the oxidation step, a rinsing is done in cold water for one minute. After the rinsing, a fixing procedure is performed in order to fix the indigo dye, which is not attached to the fabric and is kept on suspend inside the tub, into the fabric. For this step, 2g/l of indigo fixator shall be added into the tub and the closed system machine, in which the fent and the tub are located, shall be operated for three minutes.

After all these process steps, the fents can be taken into the steeping tub, as in the conventional fent dyeing methods, if desired.

As a last step, the completed fents are wrung and are dried in drying drum at a temperature between the range of 70 - 90 Ό degrees .