Indigo foam dyeing process for denim yarn

Abstract

The invention discloses an indigo foam dyeing process for denim yarn, comprising the following process steps: (1) in an oxygen-free environment, pre-reduced indigo dye and cyclodextrin are mixed by stirring, so that the cyclodextrin wraps the pre-reduced indigo dye; (2) in an oxygen-free environment, a foaming agent, a stabilizer and a penetrant are added to the indigo dye treated with cyclodextrin for foaming; (3) the foam dye solution is transported to a first dyeing unit, the foamed dye solution is applied to the surface of the denim yarn by extrusion and smearing, an inert gas is introduced into the first dyeing unit, and the dye is penetrated into the yarn and fixed by the first dyeing unit; the denim yarn enters the second dyeing unit after passing through the first dyeing unit, the foam dye solution is transported into the foam dyeing section for foam dyeing, and ultrasonic treatment is performed in the foam dyeing section; (4) the dyed yarn is passed through a sealed box for delayed oxidation and then dried. The invention can effectively improve the color fastness and levelness of indigo dyeing of denim yarn.

Description

Technical Field

[0001] The invention relates to the technical field of textiles, and in particular to an indigo foam dyeing process for denim yarn. Background Art

[0002] As a new processing technology, textile foam dyeing technology has a simple process flow. Its water-saving, energy-saving, green and low-carbon characteristics provide a new choice for the sustainable development of textile dyeing and finishing. Foam dyeing technology changes the carrier medium of dyes from water to foam, and replaces water with inert gas as the medium, which saves energy and reduces consumption, is green and environmentally friendly, realizes refined dyeing control, and gives fabrics excellent dyeing effects.

[0003] Dyeing cellulose textile raw materials with indigo dye is a very complicated process with heavy material consumption. Since indigo dye is insoluble in water and has no affinity for water, it is impossible to dye cellulose textile raw materials with indigo dye directly. Indigo must be reduced to a soluble leuco salt in a strong alkaline (caustic soda) solution with a strong reducing agent (insurance powder or sulfur-free reducing agent), and then combined with cellulose fibers and absorbed by cellulose fibers. The carbonyl group in the dye molecule forms a hydrogen bond with the hydroxyl group in cellulose and fixes on the fiber yarn. The combination of the carbonyl group in the dye molecule and the hydroxyl group in cellulose requires a certain reaction time, that is, the delayed oxidation time (inert gas protection time). If the delayed oxidation time is too short, the leuco salt of the dye that enters the cellulose yarn cannot react with the hydroxyl group on the cellulose fiber in time to form a hydrogen bond, and is oxidized to indigo by oxygen, resulting in surface floating color and poor color fastness.

[0004] In the prior art, a three-stage anaerobic system (anaerobic environment-soaking-delayed oxidation) is generally used to solve the problem of low color fastness of indigo dyeing. However, in industrial production practice, it is found that the yarn hairiness is wrapped in air and enters the box, the oxygen content increases, and as the dyeing progresses, the indigo oxidizes prematurely, which still makes it difficult for the dye liquid to continue to penetrate into the yarn, and the surface floating color and low color fastness cannot be improved. Summary of the invention

[0005] The invention provides an indigo foam dyeing process for denim yarn, which can effectively improve the color fastness and levelness of indigo dyeing of the denim yarn.

[0006] The present invention provides an indigo foam dyeing process for denim yarn, comprising the following process steps:

[0007] (1) In an oxygen-free environment, the pre-reduced indigo dye and cyclodextrin are mixed by stirring, so that the cyclodextrin encapsulates the pre-reduced indigo dye, the mixing temperature is 30-50° C., the stirring speed is 500-1000 rpm, and the stirring time is 0.5-2 hours;

[0008] (2) Foaming: in an oxygen-free environment, adding a foaming agent, a stabilizer and a penetrant to the indigo dye treated with cyclodextrin in step (1) to form foam;

[0009] (3) Dyeing: The dyeing process includes two stages. The denim yarn first enters the first dyeing unit, and the foam dye liquid is transported to the first dyeing unit. The foamed dye liquid is squeezed and applied to the surface of the denim yarn. The temperature is room temperature. Positive pressure inert gas is introduced into the first dyeing unit. The first dyeing unit allows the dye to penetrate into the yarn and fix the dye. At the same time, the cyclodextrin that wraps the dye is partially dissolved or destroyed, so that the dye penetrates into the yarn and gradually contacts the yarn; the denim yarn passes through the first dyeing unit and enters the second dyeing unit. The second dyeing unit is a foam dyeing section. Inert gas is passed through the second dyeing unit, and foam dye liquid is transported into the foam dyeing section. The foamed dye liquid is ultrasonically treated in the foam dyeing section. The ultrasonic power is 50-80W; the speed of the first dyeing unit and the second dyeing unit during the above dyeing process is 20-30m / min;

[0010] (4) The dyed yarn is passed through a sealed box to delay oxidation and then dried.

[0011] Furthermore, the amount of the foaming agent is 10-20 g / L, the amount of the stabilizer is 2-5 g / L, and the amount of the penetrant is 5-12 g / L.

[0012] Furthermore, the inert gas is nitrogen, and the pressure of the inert gas in the first dyeing stage is 1.05-1.1 MPa.

[0013] Furthermore, the delayed oxidation time is 60-100s.

[0014] Furthermore, the foaming ratio of the foaming step is 1:10-1:12.

[0015] Furthermore, in step (1), the concentration of indigo dye is 50-200 g / L, and the concentration of cyclodextrin is 50-100 g / L.

[0016] Furthermore, an inert gas is passed through the second dyeing unit at a pressure of 1-1.05 MPa.

[0017] The technical solution of the present invention has at least the following advantages:

[0018] The present invention first wraps the pre-reduced indigo dye with cyclodextrin, and then foams it to form a foam dye solution. When the yarn enters, the oxygen brought in by the hairiness will not immediately contact the dye, which can avoid premature oxidation of the dye; the dyeing stage includes two stages, the first stage allows the dye to fully penetrate the yarn and preliminarily destroys the cyclodextrin that wraps the dye, and the second stage dissolves the cyclodextrin through ultrasound and temperature control on the basis of the dye penetrating the yarn, so that the dye contacts the yarn, and then performs foam dyeing and delayed oxidation. The present invention can ensure that the dye penetrates and is fixed on the denim yarn, increase the amount of the dye fixed on the fiber, so that the favorable color of the dyed fiber, yarn or fabric can be obtained, and the color fastness and levelness of the denim yarn are theoretically guaranteed. DETAILED DESCRIPTION

[0019] The following will be combined with specific implementation methods to clearly and completely describe the technical solutions in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Embodiment 1:

[0020] An indigo foam dyeing process for denim yarn comprises the following process steps:

[0021] (1) In an oxygen-free environment, the pre-reduced indigo dye and cyclodextrin are mixed by stirring so that the cyclodextrin encapsulates the pre-reduced indigo dye, the mixing temperature is 30° C., the stirring speed is 500 rpm, and the stirring time is 2 hours; the concentration of the indigo dye is 100 g / L, and the concentration of the cyclodextrin is 50 g / L;

[0022] (2) Foaming: in an anaerobic environment, adding a foaming agent, a stabilizer and a penetrant to the indigo dye treated with cyclodextrin in step (1) to form foam, and the foaming ratio is 1:10; the amount of the foaming agent is 10 g / L, the amount of the stabilizer is 2 g / L, and the amount of the penetrant is 5 g / L;

[0023] (3) Dyeing: The dyeing process includes two stages. The denim yarn first enters the first dyeing unit, and the foamed dye liquid is transported to the first dyeing unit. The foamed dye liquid is applied to the surface of the denim yarn after extrusion. The temperature is room temperature. Positive pressure inert gas is introduced into the first dyeing unit. The function of the first dyeing unit is to enable the dye to penetrate into the yarn and fix the dye. At the same time, the cyclodextrin that wraps the dye is partially dissolved or destroyed, so that the dye penetrates into the yarn and gradually contacts with the yarn. Nitrogen is used as the inert gas with a pressure of 1.05MPa. After passing through the first dyeing unit, the denim yarn enters the second dyeing unit. The foam dyeing section is a foam dyeing section, and an inert gas is passed through the second dyeing unit at a pressure of 1MPa. The foam dye solution is transported into the foam dyeing section, and the foaming dye solution is ultrasonically treated at an ultrasonic power of 50W. In the foam dyeing section, the cyclodextrin encapsulating the dye is dissolved and the dye is released. During the above dyeing process, the speed of the first dyeing unit and the second dyeing unit is 20m / min. By setting the first dyeing unit, the positive pressure inert gas and cyclodextrin isolate the oxygen brought in by the yarn hairiness to avoid premature oxidation of the dye. In the second dyeing unit, the dye is released by temperature control and ultrasonic control, and contacts with the yarn for foam dyeing.

[0024] (4) The dyed yarn is passed through a sealed box for delayed oxidation and then dried. The delayed oxidation time is 60 seconds.

[0025] In this embodiment, the pre-reduced indigo dye is first wrapped with cyclodextrin, and then foamed to form a foam dye solution. When the yarn enters, the oxygen brought in by the hairiness will not immediately contact the dye, which can avoid premature oxidation of the dye; the dyeing stage includes two stages. The first stage allows the dye to fully penetrate the yarn and preliminarily destroys the cyclodextrin that wraps the dye. The second stage dissolves the cyclodextrin through ultrasound and temperature control on the basis of less dye penetration, so that the dye contacts the yarn, and then performs foam dyeing and delayed oxidation. This embodiment can ensure that the dye penetrates and is fixed on the denim yarn, increase the amount of dye fixed on the fiber, so that the favorable color of the dyed fiber, yarn or fabric can be obtained, and the color fastness and levelness of the denim yarn can be theoretically guaranteed. Embodiment 2:

[0026] An indigo foam dyeing process for denim yarn comprises the following process steps:

[0027] (1) In an oxygen-free environment, the pre-reduced indigo dye and cyclodextrin are mixed by stirring so that the cyclodextrin encapsulates the pre-reduced indigo dye, the mixing temperature is 50° C., the stirring speed is 1000 rpm, and the stirring time is 0.5 hour; the concentration of the indigo dye is 200 g / L, and the concentration of the cyclodextrin is 100 g / L;

[0028] (2) Foaming: in an anaerobic environment, adding a foaming agent, a stabilizer and a penetrant to the indigo dye treated with cyclodextrin in step (1) to form foam, and the foaming ratio is 1:12; the amount of the foaming agent is 20 g / L, the amount of the stabilizer is 5 g / L, and the amount of the penetrant is 12 g / L;

[0029] (3) Dyeing: The dyeing process includes two stages. The denim yarn first enters the first dyeing unit. The foam dye is transported to the first dyeing unit. The foamed dye is applied to the surface of the denim yarn after extrusion. The temperature is room temperature. Positive pressure inert gas is introduced into the first dyeing unit. The function of the first dyeing unit is to allow the dye to penetrate into the yarn and fix the dye. At the same time, the cyclodextrin that wraps the dye is partially dissolved or destroyed, so that the dye penetrates into the yarn and gradually contacts the yarn. Nitrogen is used as the inert gas with a pressure of 1.1 MPa. After passing through the first dyeing unit, the denim yarn enters the second dyeing unit. The second dyeing unit is a foam dyeing unit. In the foam dyeing section, an inert gas is passed through the second dyeing unit at a pressure of 1.05MPa. In the foam dyeing section, a foam dye solution is transported and the foaming dye solution is ultrasonically treated at an ultrasonic power of 80W. In the foam dyeing section, the cyclodextrin encapsulating the dye is dissolved and the dye is released. During the above dyeing process, the speed of the first dyeing unit and the second dyeing unit is 30m / min. By setting up the first dyeing unit, the oxygen brought in by the yarn hairiness is isolated by the positive pressure inert gas and cyclodextrin to avoid premature oxidation of the dye. In the second dyeing unit, the dye is released by temperature control and ultrasonic control, and contacts with the yarn for foam dyeing.

[0030] (4) The dyed yarn is passed through a sealed box for delayed oxidation and then dried. The delayed oxidation time is 100 seconds. Embodiment three:

[0031] An indigo foam dyeing process for denim yarn comprises the following process steps:

[0032] (1) In an oxygen-free environment, the pre-reduced indigo dye and cyclodextrin are mixed by stirring so that the cyclodextrin encapsulates the pre-reduced indigo dye, the mixing temperature is 40° C., the stirring speed is 800 rpm, and the stirring time is 1 hour; the concentration of the indigo dye is 150 g / L, and the concentration of the cyclodextrin is 60 g / L;

[0033] (2) Foaming: in an anaerobic environment, adding a foaming agent, a stabilizer and a penetrant to the indigo dye treated with cyclodextrin in step (1) to form foam, and the foaming ratio is 1:11; the amount of the foaming agent is 15 g / L, the amount of the stabilizer is 4 g / L, and the amount of the penetrant is 10 g / L;

[0034] (3) Dyeing: The dyeing process includes two stages. The denim yarn first enters the first dyeing unit, and the foamed dye liquid is transported to the first dyeing unit. The foamed dye liquid is applied to the surface of the denim yarn after extrusion. The temperature is room temperature. Positive pressure inert gas is introduced into the first dyeing unit. The function of the first dyeing unit is to enable the dye to penetrate into the yarn and fix the dye. At the same time, the cyclodextrin that wraps the dye is partially dissolved or destroyed, so that the dye penetrates into the yarn and gradually contacts with the yarn. Nitrogen is used as the inert gas with a pressure of 1.05MPa. After passing through the first dyeing unit, the denim yarn enters the second dyeing unit. The foam dyeing section is a foam dyeing section, and the second dyeing unit is passed with inert gas at a pressure of 1MPa. The foam dyeing liquid is transported into the foam dyeing section, and the foaming dyeing liquid is ultrasonically treated with an ultrasonic power of 60W. In the foam dyeing section, the cyclodextrin encapsulating the dye is dissolved and the dye is released. During the above dyeing process, the speed of the first dyeing unit and the second dyeing unit is 25m / min. By setting the first dyeing unit, the positive pressure inert gas and cyclodextrin isolate the oxygen brought in by the yarn hairiness to avoid premature oxidation of the dye. In the second dyeing unit, the dye is released by temperature control and ultrasonic control, and contacts with the yarn for foam dyeing.

[0035] (4) The dyed yarn is passed through a sealed box for delayed oxidation and then dried. The delayed oxidation time is 80 seconds.

[0036] Comparative Example:

[0037] An indigo foam dyeing process for denim yarn comprises the following process steps:

[0038] (1) In an anaerobic environment, adding a foaming agent, a stabilizer and a penetrant to the pre-reduced indigo dye to form foam, and the foaming ratio is 1:11; the amount of the foaming agent is 15 g / L, the amount of the stabilizer is 4 g / L, and the amount of the penetrant is 10 g / L;

[0039] (3) Dyeing: The foam dye solution is transported to the dyeing area, and the denim yarn is foam-dyed in an inert gas;

[0040] (4) The dyed yarn is passed through a sealed box for delayed oxidation and then dried. The delayed oxidation time is 80 seconds.

[0041] The denim yarns obtained by using Examples 1 to 3 of the present invention and the comparative example were subjected to performance tests, and the test results are shown in Table 1.

[0042] Table 1

[0043]

[0044] As can be seen from the data in the above table, the denim yarn prepared by the present invention can obtain fabrics with excellent fastness. The present invention effectively improves the color fastness and levelness of yarn dyeing by avoiding premature oxidation of the dye and allowing the dye to fully penetrate the yarn to increase the amount of dye fixed on the yarn.

[0045] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. An indigo foam dyeing process for denim yarn, characterized in that: The process steps include: (1) In an oxygen-free environment, the pre-reduced indigo dye and cyclodextrin are mixed by stirring, so that the cyclodextrin encapsulates the pre-reduced indigo dye, the mixing temperature is 30-50° C., the stirring speed is 500-1000 rpm, and the stirring time is 0.5-2 hours; (2) Foaming: in an oxygen-free environment, adding a foaming agent, a stabilizer and a penetrant to the indigo dye treated with cyclodextrin in step (1) to form foam; (3) Dyeing: The dyeing process includes two stages. The denim yarn first enters the first dyeing unit, and the foam dye liquid is transported to the first dyeing unit. The foamed dye liquid is squeezed and applied to the surface of the denim yarn. The temperature is room temperature. Positive pressure inert gas is introduced into the first dyeing unit. The first dyeing unit allows the dye to penetrate into the yarn and fix the dye. At the same time, the cyclodextrin that wraps the dye is partially dissolved or destroyed, so that the dye penetrates into the yarn and gradually contacts the yarn; the denim yarn passes through the first dyeing unit and enters the second dyeing unit. The second dyeing unit is a foam dyeing section. Inert gas is passed through the second dyeing unit, and foam dye liquid is transported into the foam dyeing section. The foamed dye liquid is ultrasonically treated in the foam dyeing section. The ultrasonic power is 50-80W; the speed of the first dyeing unit and the second dyeing unit during the above dyeing process is 20-30m / min; (4) The dyed yarn is passed through a sealed box to delay oxidation and then dried.

2. The indigo foam dyeing process for denim yarn according to claim 1, characterized in that: The dosage of the foaming agent is 10-20 g / L, the dosage of the stabilizer is 2-5 g / L, and the dosage of the penetrant is 5-12 g / L.

3. The indigo foam dyeing process for denim yarn according to claim 1, characterized in that: The inert gas is nitrogen, and the pressure of the inert gas in the first dyeing stage is 1.05-1.1 MPa.

4. The indigo foam dyeing process for denim yarn according to claim 1, characterized in that: The delayed oxidation time is 60-100s.

5. The indigo foam dyeing process for denim yarn according to claim 1, characterized in that: The foaming ratio of the foaming step is 1:10-1:

12.

6. The indigo foam dyeing process for denim yarn according to claim 1, characterized in that: In the step (1), the concentration of indigo dye is 50-200 g / L, and the concentration of cyclodextrin is 50-100 g / L.

7. The indigo foam dyeing process for denim yarn according to claim 1, characterized in that: The second dyeing unit is filled with inert gas at a pressure of 1-1.05 MPa.

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