A method for indigo dyeing of cotton fabric based on direct electrochemical reduction

Abstract

The present invention provides a method for dyeing cotton fabric indigo based on direct electrochemical reduction, comprising the steps of: S1, using a flow plate-frame electrolysis device to perform direct electrochemical reduction on indigo dye; S2, sending the reduced dye to a dyeing device to dye cotton fabric; S3, sending the dyed dye liquor to a flow plate-frame electrolysis device, and repeating steps S1-S2 multiple times. The present invention uses a flow plate-frame electrolysis device to make indigo directly contact with an electrode to obtain electrons, thereby reducing indigo. It is a direct electrochemical reduction process, does not introduce any metal ions, and the reaction product is pollution-free, clean and environmentally friendly, has good application prospects, is superior to traditional processes in terms of energy consumption and cost, and has a better dyeing effect than traditional dyeing, and can circulate the dye liquor for multiple times, and the K / S apparent color depth does not fluctuate much.

Description

Technical Field

[0001] The invention relates to a cotton fabric dyeing method, in particular to an indigo dyeing method for cotton fabric based on direct electrochemical reduction. Background Art

[0002] Indigo dye is commonly used in the denim dyeing process, but indigo is insoluble in water and has no affinity for cotton fabrics. It needs to be reduced to a leuco form by a reducing agent under alkaline conditions to complete dyeing. In the traditional dyeing process, sodium dithionite (commonly known as hydrosulfite) is used as a reducing agent to reduce indigo to a leuco form for dyeing. However, hydrosulfite is non-renewable and produces sulfur-containing compounds after decomposition, which pollutes the environment.

[0003] In recent years, the indirect electrochemical reduction of indigo has been very popular. The system uses iron ion complexes as a bridge to obtain electrons from the cathode and then transfer the electrons to the dye to reduce it. However, the disadvantage is that this process introduces metal ions such as iron ions, which not only have a certain impact on the fabric, but also cause a certain degree of pollution to the environment. Therefore, it is necessary to design a method for direct electrochemical reduction of indigo without introducing any metal ions to overcome the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a method for indigo dyeing of cotton fabric based on direct electrochemical reduction in order to solve the problems of high pollution, high energy consumption and high emission in traditional processes and the large amount of metal ions introduced by existing indirect electrochemical reduction methods.

[0005] The present invention is achieved in that:

[0006] The present invention provides a method for indigo dyeing of cotton fabric based on direct electrochemical reduction, comprising the steps of:

[0007] S1. Direct electrochemical reduction of indigo dye using a flow plate and frame electrolysis device;

[0008] S2, sending the reduced dye to a dyeing device to dye the cotton fabric;

[0009] S3, sending the dyed dye solution to the flow plate and frame electrolysis device, and repeating steps S1-S2 for multiple times.

[0010] The present invention uses a flow plate and frame electrolysis device to make indigo directly contact with electrodes to obtain electrons, thereby reducing indigo. This is a direct electrochemical reduction process, does not introduce any metal ions, and the reaction products are pollution-free, clean and environmentally friendly. It has good application prospects and is superior to traditional processes in terms of energy consumption and cost. The dyeing effect is better than traditional dyeing, and the dye solution can be recycled for multiple times, and the K / S apparent color depth fluctuation is not large.

[0011] Furthermore, the flow plate and frame electrolysis device includes a plate and frame electrolytic cell, a cathode liquid storage tank and an anode liquid storage tank. The cathode liquid storage tank and the anode liquid storage tank are both provided with a feed port, a discharge port and an air outlet. The cathode liquid storage tank and the anode liquid storage tank respectively deliver the cathode liquid and the anode liquid to the cathode and anode of the plate and frame electrolytic cell through the discharge port. The cathode liquid storage tank is also provided with a discharge hole to deliver the reduced dye to the dyeing device.

[0012] Furthermore, the air outlets of the cathode liquid storage tank and the anode liquid storage tank are both connected with cold hydrazine to prevent excessive pressure in the tanks.

[0013] Furthermore, a water stop valve is connected to the discharge hole of the cathode liquid storage tank. After the indigo is completely reduced, the water stop valve is opened to send the reduced dye to the dyeing device.

[0014] Furthermore, the cathode liquid is indigo and an alkaline solution, the ratio of the indigo to the alkaline solution is 2:1, and the anode liquid is an alkaline solution.

[0015] Furthermore, in step S1, the indigo dye is completely reduced at a voltage of 10-15 V, a temperature of 40-60° C., a liquid inlet flow rate of 10-20 ml / min, and ultrasound for 1-2 h.

[0016] Furthermore, the dyeing device comprises an infiltration pool, a dyeing vat and a washing pool which are arranged side by side in sequence, and rollers which are connected to each other are arranged on the infiltration pool, the dyeing vat and the washing pool.

[0017] Furthermore, in step S2, the cotton fabric is infiltrated in an infiltration tank, colored in a dyeing vat, washed to remove floating color in a washing tank, and finally oxidized and air-dried to complete the dyeing of the cotton fabric.

[0018] Furthermore, the cotton fabric is yarn or twill cotton.

[0019] The present invention has the following beneficial effects:

[0020] 1. The reaction product of the present invention is pollution-free, clean and environmentally friendly. From a process perspective, it is far superior to the existing insurance powder system and indirect electrochemical reduction system. The yarn after dyeing with the technology has good wear resistance, elongation at break, breaking strength and K / S apparent color depth, and is also superior to traditional processes in terms of energy consumption and cost.

[0021] 2. The dye liquor produced in the present invention can be recycled, and after cyclic dyeing, the K / S apparent color depth does not fluctuate much. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a schematic diagram of the structure of the device used in the production in the embodiment of the present invention;

[0024] Figure 2 It is a schematic diagram of the structure of the functional plate in the plate-frame electrolytic cell in an embodiment of the present invention;

[0025] Figure 3 It is a comparison diagram of K / S curves of multiple dyeing of yarn in an embodiment of the present invention and multiple dyeing of traditional yarn;

[0026] Figure 4 It is a K / S curve comparison diagram of the multiple dyeing of three-up-one-down twill cotton fabric in the embodiment of the present invention and the multiple dyeing of three-up-one-down twill cotton fabric in the conventional method;

[0027] Figure 5 This is a K / S curve diagram of yarn dyeing after multiple electrolysis and one dyeing in Example 5 of the present invention;

[0028] Figure 6 This is a K / S curve diagram of the three-up and one-down twill cotton fabric subjected to multiple electrolysis and single dyeing in Example 6 of the present invention.

[0029] In the figure: 1, plate and frame electrolytic cell; 2, cathode liquid storage tank; 3, anode liquid storage tank; 4, peristaltic pump; 5, cold hydrazine; 6, anode; 7, cathode; 8, water stop valve; 9, permeation tank; 10, dye vat; 11, washing tank; 12-functional board; 13-pipeline; 14-groove. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0031] See also Figure 1 The device used in the embodiment of the present invention includes a flow plate and frame electrolysis device and a dyeing device. The flow plate and frame electrolysis device includes a plate and frame electrolytic cell 1, a cathode liquid storage tank 2 and an anode liquid storage tank 3.

[0032] The cathode liquid storage tank 2 and the anode liquid storage tank 3 are both provided with a feed port, a discharge port and an air outlet. To prevent excessive pressure in the tank, a cold hydrazine 5 is connected to the air outlet. The cathode liquid storage tank 2 and the anode liquid storage tank 3 respectively deliver the cathode liquid and the anode liquid to the cathode 7 and the anode 6 of the plate-frame electrolytic cell 1 through the discharge port. The cathode 7 and the anode 6 are on both sides of the plate-frame electrolytic cell 1 and are connected to a DC power supply. The cathode liquid is indigo and an alkaline solution, and the anode liquid is an alkaline solution. After electrolysis, the cathode liquid and the anode liquid are respectively returned to the cathode liquid storage tank 2 and the anode liquid storage tank 3 from the feed port. Indigo directly contacts the electrode to obtain electrons and completes reduction. The cathode liquid storage tank 2 is also provided with a discharge hole, and a water stop valve 8 is connected to the discharge hole to prevent backflow. The reduced indigo is delivered to the dyeing device from the discharge hole.

[0033] The dyeing device includes an infiltration pool 9, a dye vat 10 and a washing pool 11 which are arranged side by side in sequence. The infiltration pool 9, the dye vat 10 and the washing pool 11 are provided with rollers connected to each other. The cotton fabric is infiltrated in the infiltration pool 9, colored in the dye vat 10, and washed away with floating color in the washing pool 11, and finally oxidized and air-dried to complete the dyeing of the cotton fabric.

[0034] The dye liquor after dyeing can be recycled, and the dye liquor after dyeing can be pumped to the cathode tank for repeated electrolysis by reversing the direction of the peristaltic pump 4.

[0035] like Figure 2 As shown, the core component of the plate and frame electrolytic cell 1 is a functional plate 12 (divided into a cathode functional plate and an anode functional plate). The functional plate 12 is provided with a pipe 13 for supplying cathode liquid or anode liquid, and a groove 14 is provided in the middle thereof. The groove 14 and other components cooperate to form a cathode chamber or an anode chamber. Depending on the specific reaction conditions, RVC porous glass carbon or the like can be filled in the cathode chamber to form a three-dimensional electrode system, thereby further increasing the contact area between the dye and the electrode and enhancing the reduction effect.

[0036] Therefore, the indigo dyeing method of cotton fabric based on direct electrochemical reduction of the present invention comprises the steps of:

[0037] S1. Direct electrochemical reduction of indigo dye using a flow plate and frame electrolysis device;

[0038] S2, sending the reduced dye to a dyeing device to dye the cotton fabric;

[0039] S3, sending the dyed dye solution to the flow plate and frame electrolysis device, and repeating steps S1-S2 for multiple times.

[0040] Example 1

[0041] Prepare a cathode solution with an indigo concentration of 80-120 g / L (indigo: sodium hydroxide = 2:1), and prepare an anode solution with a sodium hydroxide concentration of 20-40 g / L.

[0042] In the flow plate and frame electrolysis device, under the optimal process conditions: voltage 10--15V, temperature 40--60℃, liquid flow rate 10--20ml / min, ultrasound 1--2h, indigo is completely reduced. Then take 30cm yarn, dye, oxidize, air dry, and measure its K / S value.

[0043] Comparative Example 1

[0044] Prepare a dye solution with an indigo concentration of 80-120g / L (indigo: sodium hydroxide = 2:1), and add the same concentration of hydrosulfite to reduce it. After complete reduction, take 30cm of yarn, dye it, oxidize it, air-dry it, and measure its K / S value.

[0045] Example 2

[0046] Prepare a cathode solution with an indigo concentration of 80-120 g / L (indigo: sodium hydroxide = 2:1), and prepare an anode solution with a sodium hydroxide concentration of 20-40 g / L.

[0047] In the flow plate and frame electrolysis device, under the optimal process conditions: voltage 10--15V, temperature 40--60℃, liquid flow rate 10--20ml / min, ultrasound 1--2h, indigo is completely reduced. Then take 30cm yarn, dye, oxidize, air dry, repeat several times, and measure its K / S value.

[0048] Comparative Example 2

[0049] Prepare a dye solution with an indigo concentration of 80-120g / L (indigo: sodium hydroxide = 2:1), and add the same concentration of hydrosulfite to reduce it. After complete reduction, take 30cm of yarn, dye, oxidize, and air-dry it, repeat the process several times, and measure its K / S value.

[0050] Example 3

[0051] Prepare a cathode solution with an indigo concentration of 80-120 g / L (indigo: sodium hydroxide = 2:1), and prepare an anode solution with a sodium hydroxide concentration of 20-40 g / L.

[0052] In the flow plate and frame electrolysis device, under the optimal process conditions: voltage 10--15V, temperature 40--60℃, liquid flow rate 10--20ml / min, ultrasound 1--2h, indigo is completely reduced. Then take a 5cm*5cm three-up and one-down twill cotton cloth, dye it, oxidize it, and air dry it, and measure its K / S value.

[0053] Comparative Example 3

[0054] Prepare a dye solution with an indigo concentration of 80-120g / L (indigo: sodium hydroxide = 2:1), and add the same concentration of hydrosulfite to reduce it. After complete reduction, take a 5cm*5cm three-up-one-down twill cotton cloth, dye it, oxidize it, and air-dry it, and then measure its K / S value.

[0055] Example 4

[0056] Prepare a cathode solution with an indigo concentration of 80-120 g / L (indigo: sodium hydroxide = 2:1), and prepare an anode solution with a sodium hydroxide concentration of 20-40 g / L.

[0057] In the flow plate and frame electrolysis device, under the optimal process conditions: voltage 10--15V, temperature 40--60℃, liquid flow rate 10--20ml / min, ultrasound 1--2h, indigo is completely reduced. Then take a 5cm*5cm three-up and one-down twill cotton cloth, dye, oxidize, air dry, repeat the process several times, and measure its K / S value.

[0058] Comparative Example 4

[0059] Prepare a dye solution with an indigo concentration of 80-120g / L (indigo: sodium hydroxide = 2:1), and add the same concentration of hydrosulfite to reduce it. After complete reduction, take a 5cm*5cm three-up and one-down twill cotton cloth, dye, oxidize, and air-dry it, repeat the process several times, and measure its K / S value.

[0060] Example 5

[0061] Prepare a cathode solution with an indigo concentration of 80-120 g / L (indigo: sodium hydroxide = 2:1), and prepare an anode solution with a sodium hydroxide concentration of 20-40 g / L.

[0062] In the flow plate and frame electrolysis device, under the optimal process conditions: voltage 10--15V, temperature 40--60℃, liquid flow rate 10--20ml / min, ultrasound 1--2h, indigo is completely reduced. Then take 30cm of pure cotton yarn, dye, oxidize, air dry, and measure its K / S value.

[0063] The dye solution was electrolyzed every other day, and then 30 cm of pure cotton yarn was taken, dyed, oxidized, and air-dried, and its K / S value was measured. The results are as follows: Figure 5 shown.

[0064] Example 6

[0065] Prepare a cathode solution with an indigo concentration of 80-120 g / L (indigo: sodium hydroxide = 2:1), and prepare an anode solution with a sodium hydroxide concentration of 20-40 g / L.

[0066] In the flow plate and frame electrolysis device, under the optimal process conditions: voltage 10--15V, temperature 40--60℃, liquid flow rate 10--20ml / min, ultrasound 1--2h, indigo is completely reduced. Then take a 5cm*5cm three-up and one-down twill cotton cloth, dye it, oxidize it, air dry it, and measure its K / S value.

[0067] Repeat the electrolysis of the dye solution every other day, then take a 5cm*5cm three-up and one-down twill cotton cloth, dye it, oxidize it, and air-dry it, and measure its K / S value. The results are as follows: Figure 6 shown.

[0068] According to Examples 1 to 4 and Comparative Examples 1 to 4, the yarn and the three-up-one-down twill cotton fabric are dyed once or multiple times, respectively, and the obtained data are shown in Table 1, and the K / S curve comparison diagram is shown in Table 1. Figure 3 , Figure 4 As shown:

[0069] Table 1 K / S values ​​of fabrics dyed once or multiple times by conventional and direct electrochemical methods

[0070]

[0071]

[0072] It can be seen that through the flow plate and frame electrolysis device, indigo is directly in contact with the electrode to obtain electrons, and then directly electrochemically reduced to dye yarn and twill, and the effect is better than traditional dyeing.

[0073] The present invention does not introduce metal ions, the reaction products are pollution-free, clean and environmentally friendly, and is far superior to the existing insurance powder system and indirect electrochemical reduction system from a process perspective. The yarn after dyeing with the technology has good wear resistance, elongation at break, breaking strength and K / S apparent color depth, and is also superior to traditional processes in terms of energy consumption and cost.

[0074] At the same time, through Examples 5 and 6, from Figure 5 , Figure 6 It can be seen that the dye liquor produced in the present invention can be recycled, and after cyclic dyeing, the K / S apparent color depth does not fluctuate much.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for indigo dyeing of cotton fabric based on direct electrochemical reduction, characterized in that: Includes steps: S1. Direct electrochemical reduction of indigo dye using a flow plate and frame electrolysis device; S2, sending the reduced dye to a dyeing device to dye the cotton fabric; S3, sending the dyed dye solution to the flow plate and frame electrolysis device, and repeating steps S1-S2 multiple times; The flow plate-and-frame electrolysis device comprises a plate-and-frame electrolytic cell, a cathode liquid storage tank and an anode liquid storage tank, wherein the cathode liquid storage tank and the anode liquid storage tank are both provided with a feed port, a discharge port and an air outlet, and the cathode liquid storage tank and the anode liquid storage tank respectively deliver the cathode liquid and the anode liquid to the cathode and the anode of the plate-and-frame electrolytic cell through the discharge port, and the cathode liquid storage tank is also provided with a discharge port to deliver the reduced dye to the dyeing device; The core component of the plate-and-frame electrolyzer is the functional plate, which is divided into a cathode functional plate and an anode functional plate. The functional plate is provided with a pipeline for the cathode liquid or the anode liquid to enter and exit, and a groove is provided in the middle. The groove and other components cooperate to form a cathode chamber or an anode chamber. The cathode chamber is filled with RVC porous glassy carbon to form a three-dimensional electrode system. The cathode liquid is indigo and alkaline solution, the ratio of indigo to alkaline solution is 2:1, and the concentration of indigo is 80-120 g / L; The anolyte is an anolyte with a sodium hydroxide concentration of 20-40 g / L; The indigo dye was completely reduced at a voltage of 10-15V, a temperature of 40-60℃, a liquid flow rate of 10-20ml / min, and ultrasound for 1-2h; The cotton fabric is yarn or twill cotton; Repeat steps S1-S2 2~5 times.

2. The method for indigo dyeing of cotton fabric based on direct electrochemical reduction according to claim 1, characterized in that: The gas outlets of the cathode liquid storage tank and the anode liquid storage tank are both connected with cold hydrazine.

3. The method for indigo dyeing of cotton fabric based on direct electrochemical reduction according to claim 1, characterized in that: The discharge hole of the cathode liquid storage tank is connected with a water stop valve.

4. The method for indigo dyeing of cotton fabric based on direct electrochemical reduction according to claim 1, characterized in that: The dyeing device comprises an infiltration pool, a dyeing vat and a washing pool which are arranged in sequence and side by side, and rollers which are connected to each other are arranged on the infiltration pool, the dyeing vat and the washing pool.

5. The method for indigo dyeing of cotton fabric based on direct electrochemical reduction according to claim 1, characterized in that: In step S2, the cotton fabric is infiltrated in an infiltration tank, colored in a dyeing vat, washed to remove floating color in a washing tank, and finally oxidized and air-dried to complete the dyeing of the cotton fabric.

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