A method for indigo dyeing of cotton cloth

Abstract

The present invention discloses a method for indigo dyeing of cotton cloth, which relates to the technical field of dyeing and finishing, and comprises the following steps: impregnating cotton cloth with a surfactant to form a wet cotton cloth; in an inert gas environment, heating and sublimating indigo powder to form a mixed gas; conducting a uniform spraying of the mixed gas onto the wet cotton cloth to condense and form a first dyed cloth; treating the first dyed cloth with ultrasound to form a second dyed cloth; spraying the second dyed cloth with steam to form a third dyed cloth; and drying the third dyed cloth with hot air. The present invention sublimates indigo powder in an inert gas environment to form a mixed gas, and sprays the mixed gas onto the cotton cloth impregnated with a surfactant, and then ultrasonically treats, steam-sprays, and dries the cotton cloth, so that the indigo dyeing effect is good, the dyeing degree is deep, the dyeing is uniform, and the color fastness is high.

Description

Technical Field

[0001] The invention relates to the technical field of dyeing and finishing, and in particular to a method for indigo dyeing of cotton cloth. Background Art

[0002] When dyeing cotton cloth with indigo, it is usually necessary to reduce the indigo to a leuco form before dyeing the cotton cloth. This process will use a large amount of chemical reagents such as insurance powder and caustic soda, which will easily produce a large amount of difficult-to-treat sulfur-containing alkaline colored wastewater, causing serious pollution to the environment.

[0003] Some researchers dye fabrics by sublimating indigo into gaseous dyes. Although this can reduce the use of chemical reagents and avoid the generation of wastewater, the technical method is not perfect. The dyeing effect of the fabric is poor, the indigo dyeing depth is shallow and uneven, and it fades severely after washing. Summary of the invention

[0004] The object of the present invention is to overcome the shortcomings of the prior art. The present invention provides a method for indigo dyeing of cotton cloth, wherein indigo powder is sublimated in an inert gas environment to form a mixed gas, and the mixed gas is sprayed onto cotton cloth impregnated with a surfactant, and then the cotton cloth is subjected to ultrasonic treatment, steam spray treatment and drying treatment. The indigo dyeing effect is good, the dyeing degree is deep, the dyeing is uniform, and the color fastness is high.

[0005] The present invention provides a method for indigo dyeing of cotton cloth, comprising the following steps:

[0006] Dyeing preparation: dip cotton cloth into a surfactant with a concentration of 3 to 10 g / L to form a wet cotton cloth, and control the rolling rate to be 100 to 150%;

[0007] Indigo sublimation, in an inert gas environment, heating the indigo powder to sublimate to form a mixed gas, wherein the heating temperature of the indigo powder is in the range of 300 to 320°C;

[0008] Desublimation dyeing, the mixed gas is guided out and sprayed evenly onto the wet cotton cloth to desublimate to form a first dyed cloth, and the spraying pressure of the mixed gas is in the range of 0.4-0.5 MPa;

[0009] Ultrasonic treatment, using ultrasonic waves to treat the first dyed cloth to form a second dyed cloth, the frequency range of the ultrasonic treatment is 30 to 50 MHz;

[0010] Steam jet treatment, using 130-140° C. steam to jet the second dyed cloth to form a third dyed cloth, the jet flow rate of the steam being in the range of 30-40 m / s;

[0011] The third dyed cloth is dried using hot air at 110-120°C.

[0012] Specifically, the surfactant is composed of one or more of fatty alcohol polyoxyethylene ether, sodium butylnaphthalene sulfonate, and sulfosuccinate.

[0013] Specifically, before the desublimation dyeing, the temperature of the wet cotton cloth is controlled at 40-90°C.

[0014] Specifically, the inert gas includes nitrogen, argon or helium.

[0015] Specifically, the indigo sublimation pressure is maintained at 6×10 5 ~7×10 5 Pa.

[0016] Specifically, the concentration of gaseous indigo in the mixed gas is in the range of 5 to 10 kg / m 3 .

[0017] Specifically, the injection flow rate of the mixed gas ranges from 1200 to 1800 ml / min.

[0018] Specifically, while the ultrasonic treatment is being performed, water mist is sprayed onto the ultrasonic treatment area, the droplet size of the water mist is 200-300 μm, and the spraying flow rate of the water mist is 700-900 ml / min.

[0019] Specifically, the following steps are also included:

[0020] The wet cotton cloth passes through the spraying area of ​​the mixed gas at a first vehicle speed, wherein the first vehicle speed is 10 to 50 m / min;

[0021] The first dyed fabric passes through the ultrasonic treatment area at a second speed, and the second speed is 25-35 m / min;

[0022] The second dyed fabric passes through the steam jet treatment area at a third speed, and the third speed is 50-60 m / min;

[0023] The third dyed cloth passes through the drying treatment area at a fourth speed, and the fourth speed is 10-20 m / min.

[0024] Specifically, the dyeing preparation also includes pre-treatment of the cotton cloth, and the pre-treatment includes singeing, desizing, scouring, bleaching and mercerizing in sequence.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] Dipping cotton cloth in surfactant can improve the binding ability between cotton cloth and indigo, and also promote the penetration and diffusion of indigo in cotton cloth;

[0027] Indigo powder is heated and sublimated in an inert gas environment to form a mixed gas, which is then sprayed onto wet cotton cloth, so that the gaseous indigo in the mixed gas can better penetrate and condense into the fibers of the cotton cloth;

[0028] Ultrasonic treatment of the first dyed cloth can further diffuse and penetrate the indigo into the fibers of the cotton cloth, thereby improving the dyeing depth and dyeing uniformity;

[0029] Steam jet treatment of the second dyed cloth can fix the indigo on the fibers of the cotton cloth;

[0030] Drying the third dyed cloth can further improve the fixation of indigo and prevent fading. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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.

[0032] Figure 1 It is a flow chart of the method for indigo dyeing of cotton cloth in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] 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.

[0034] First, it should be noted that the cotton cloth is subjected to various treatments in a single-layer form, including padding, desublimation dyeing, ultrasonic treatment, steam jet treatment, and drying treatment.

[0035] Figure 1 The flowchart of the method for indigo dyeing of cotton cloth in an embodiment of the present invention is shown, comprising the following steps:

[0036] S1, staining preparation;

[0037] The cotton cloth is dipped into a surfactant with a concentration of 3 to 10 g / L to form a wet cotton cloth, and the rolling rate is controlled at 100 to 150%; the surfactant can change the interface state of the cotton cloth surface and improve the binding ability of the cotton cloth and indigo; the surfactant can be evenly distributed on the cotton cloth by dipping and padding; a reasonable concentration of surfactant and a reasonable rolling rate can effectively improve the binding ability of the cotton cloth and indigo, and promote the penetration and diffusion of indigo in the cotton cloth, so as to prepare for subsequent sublimation dyeing.

[0038] The surfactant is composed of one or more of fatty alcohol polyoxyethylene ether, sodium butylnaphthalene sulfonate, and sulfosuccinate;

[0039] Fatty alcohol polyoxyethylene ether is a nonionic surfactant with high stability, good water solubility, electrolyte resistance, easy biodegradation, small foam, and can promote the penetration and diffusion of indigo in cotton cloth; sodium butylnaphthalene sulfonate is an anionic surfactant with outstanding wetting and penetration ability, and can strongly promote the penetration and diffusion of indigo in cotton cloth; sulfosuccinate is an anionic surfactant with excellent wettability and good permeability, and can also strongly promote the penetration and diffusion of indigo in cotton cloth;

[0040] Preferably, the surfactant is composed of fatty alcohol polyoxyethylene ether and sulfosuccinate, and the combination of the two can show a significant synergistic effect, effectively promoting the penetration and diffusion of indigo in cotton cloth, and preparing for subsequent desublimation dyeing.

[0041] In some specific embodiments, before the wet cotton cloth enters the subsequent desublimation dyeing process, the temperature of the wet cotton cloth is controlled at 40-90° C., which can provide good temperature conditions for the subsequent desublimation dyeing, so that the gaseous indigo can be smoothly desublimated in the wet cotton cloth, and can also enhance the activity of the surfactant and improve the diffusion and penetration ability of the desublimated indigo.

[0042] In some specific embodiments, the dyeing preparation also includes pre-treatment of the cotton cloth, and the pre-treatment includes singeing, desizing, scouring, bleaching and mercerizing in sequence. By pre-treating the cotton cloth, impurities on the cotton cloth, such as oil wax, pectin, pigment and cottonseed hull, are removed, so that the cotton cloth has a white appearance, soft feel, good wettability and permeability, and provides the necessary conditions for subsequent dyeing and finishing.

[0043] S2, indigo sublimation;

[0044] After the indigo powder sublimates into gaseous indigo, it can more easily enter the fibers of cotton cloth.

[0045] In an inert gas environment, the indigo powder is heated and sublimated to form a mixed gas. In an inert gas environment, oxygen is isolated, which can prevent the indigo powder from being oxidized and ineffective during the heating and sublimation process. At the same time, it also prevents the sublimated gaseous indigo from contacting with oxygen during the heating process and causing a flash explosion, thereby ensuring the safety of the indigo sublimation process. The gaseous indigo and the inert gas form the mixed gas.

[0046] Specifically, the heating temperature range of the indigo powder is 300-320°C. Usually, the indigo powder will sublimely appear when heated to 170°C, and purple-red gas will appear. When the temperature exceeds 390°C, the indigo powder will decompose. Considering efficiency and cost comprehensively, it is most appropriate to sublimate the indigo powder at a temperature of 300-320°C to form gaseous indigo. Not only is the sublimation speed fast, but it is also conducive to maintaining the temperature of the mixed gas, thereby avoiding the gaseous indigo from condensing in the outlet pipeline in advance when the mixed gas is used later, causing blockage of the outlet pipeline.

[0047] Furthermore, the indigo sublimation is carried out in a closed chamber. During the indigo sublimation process, the amount of inert gas introduced is controlled to maintain the pressure in the chamber at 6×10 5 ~7×10 5 Pa, that is, the pressure of the indigo sublimation is maintained at 6×10 5 ~7×10 5 Pa, so that the indigo powder can sublimate to form a gaseous indigo with a sufficient concentration. The concentration of the gaseous indigo in the mixed gas ranges from 5 to 10 Kg / m 3 If the concentration of gaseous indigo is too low, a large amount of inert gas will be consumed in the subsequent desublimation dyeing process. If the concentration of gaseous indigo is too high, a higher cavity pressure needs to be provided, which is not conducive to safety.

[0048] In addition, the pressure in the chamber is maintained at 6×10 5 ~7×10 5 Pa also facilitates the extraction of the mixed gas to form a sufficiently strong airflow.

[0049] In some specific embodiments, the inert gas includes nitrogen, argon or helium. Preferably, nitrogen is used because it has the lowest cost.

[0050] S3, sublimation staining;

[0051] The mixed gas is discharged and uniformly sprayed onto the wet cotton cloth for condensation to form a first dyed cloth. The spray pressure range of the mixed gas is 0.4-0.5 MPa. With the help of the spray force, the gaseous indigo in the mixed gas can penetrate into the fibers of the cotton cloth and then condense, thereby avoiding the indigo adhering only to the surface of the cotton cloth and obtaining a good dyeing depth. If the spray pressure of the mixed gas is too low, the gaseous indigo cannot penetrate into the fibers of the cotton cloth for condensation, and it is difficult to obtain a good dyeing depth. If the spray pressure of the mixed gas is too high, it is easy to damage the cotton cloth and waste a large amount of mixed gas.

[0052] Furthermore, the injection flow rate of the mixed gas ranges from 1200 to 1800 ml / min. The injection flow rate of the mixed gas affects the color intensity of the cotton cloth. If the injection flow rate is low, the color of the cotton cloth is light, and if the injection flow rate is high, the color of the cotton cloth is dark.

[0053] Furthermore, the wet cotton cloth passes through the injection area of ​​the mixed gas at a first vehicle speed, and the first vehicle speed is 10 to 50 m / min. The first vehicle speed also affects the color intensity of the cotton cloth. If the vehicle speed is slow, the color of the cotton cloth is dark, and if the vehicle speed is fast, the color of the cotton cloth is light.

[0054] The injection pressure and injection flow rate of the mixed gas and the first vehicle speed cooperate with each other to allow enough gaseous indigo to penetrate into the fibers of the cotton cloth for condensation, thereby improving the indigo dyeing effect of the cotton cloth and making the color depth of the cotton cloth controllable.

[0055] In some specific embodiments, the desublimation dyeing process is carried out in a relatively closed box, and an inert gas can be used to form an oxygen-free environment in the spraying area of ​​the mixed gas, and then the mixed gas itself continues to maintain the oxygen-free environment, which can reduce the risk of oxidation of gaseous indigo; and can also reduce the escape of the mixed gas, facilitating the recycling of the mixed gas.

[0056] The recovered mixed gas can first be passed into cold water to collect the residual indigo, and then filtered, dried and deoxygenated in sequence to recover the inert gas.

[0057] S4, ultrasonic treatment;

[0058] The first dyed cloth is treated with ultrasound to form a second dyed cloth. The frequency range of the ultrasound treatment is 30-50 MHz. The ultrasound vibrates the indigo so that the indigo further diffuses and penetrates into the fibers of the cotton cloth, thereby improving the dyeing depth and dyeing uniformity.

[0059] Furthermore, the first dyed cloth passes through the ultrasonic treatment area at a second speed, and the second speed is 25 to 35 m / min. If the second speed is too fast, the first dyed cloth cannot be fully subjected to ultrasonic vibration treatment. If the second speed is too slow, production efficiency is reduced. Specifically, the first dyed cloth is made to slide along the surface of the working area of ​​the ultrasonic vibrator so that the first dyed cloth can be fully subjected to ultrasonic treatment.

[0060] In addition, in some specific embodiments, while the ultrasonic treatment is being carried out, water mist is sprayed on the ultrasonic treatment area, the droplet size of the water mist is 200-300 μm, and the spraying flow rate of the water mist is 700-900 ml / min, so as to increase the water content of the first dyed cloth, so that the indigo can further penetrate and diffuse into the fibers of the cotton cloth under the vibration of the ultrasonic wave; moreover, the water mist can form a water film between the first dyed cloth and the working area of ​​the ultrasonic vibrator, thereby reducing the friction between the cotton cloth and the ultrasonic vibrator and reducing the risk of damage to the cotton cloth; in addition, the water mist can also help cool the ultrasonic vibrator and extend the working life of the ultrasonic vibrator.

[0061] S5, steam jet treatment;

[0062] The second dyed cloth is sprayed with steam at 130-140°C to form a third dyed cloth. The steam jet velocity range is 30-40m / s. The high temperature of the steam and the force of the jet can heat the second dyed cloth evenly, making it easier for indigo to be fixed to the fibers of the cotton cloth, thereby improving the color fastness of the cotton cloth. At the same time, the moisture content of the second dyed cloth can be reduced, reducing the difficulty of subsequent drying treatment, and removing excess indigo from the surface of the second dyed cloth.

[0063] Specifically, the steam injection flow rate is 3000-4200 ml / min. If the injection flow rate is too low, it is easy to cause uneven heating of the second dyed cloth, causing color difference and color spots. If the injection flow rate is too high, it causes steam waste and increases production costs.

[0064] Furthermore, the second dyed cloth passes through the steam jet treatment area at a third speed, and the third speed is 50-60 m / min. If the third speed is too fast, the second dyed cloth is not sufficiently in contact with the steam, and the color fastness of the cotton cloth cannot be effectively improved. If the third speed is too slow, steam is wasted, which increases production costs.

[0065] S6, drying treatment;

[0066] The third dyed cloth is dried using hot air at 110-120° C. The third dyed cloth is dried using hot air at a suitable temperature, which has high drying efficiency and less energy consumption, and can further improve the fixation of indigo and prevent fading.

[0067] Specifically, the third dyed cloth passes through the drying treatment area at a fourth speed, and the fourth speed is 10-20 m / min. If the fourth speed is too fast, the third dyed cloth cannot be completely dried. If the fourth speed is too slow, the third dyed cloth will be over-dried, reducing the softness of the cotton cloth.

[0068] The invention provides a method for indigo dyeing of cotton cloth. By pre-treating the cotton cloth, impurities such as oil wax, pectin, pigment and cottonseed hull on the cotton cloth are removed, so that the cotton cloth has a white appearance, a soft hand feel and good wettability and permeability, thereby providing necessary conditions for subsequent dyeing and finishing.

[0069] The cotton cloth is dipped into the surfactant, which can change the interfacial state of the cotton cloth surface and improve the binding ability between the cotton cloth and indigo. The surfactant can be evenly distributed on the cotton cloth by dipping and padding. A reasonable concentration of surfactant and a reasonable rolling rate can effectively improve the binding ability between the cotton cloth and indigo, and promote the penetration and diffusion of indigo in the cotton cloth, preparing for the subsequent sublimation dyeing.

[0070] Controlling the temperature of the wet cotton cloth within a reasonable range can provide good temperature conditions for subsequent desublimation dyeing, so that the gaseous indigo can be desublimated smoothly in the wet cotton cloth, and can also enhance the activity of the surfactant and improve the diffusion and penetration ability of the desublimated indigo.

[0071] The indigo powder is heated and sublimated in an inert gas environment to form a mixed gas, which isolates oxygen and prevents the indigo powder from being oxidized and ineffective during the heating and sublimation process. It also prevents the sublimated gaseous indigo from coming into contact with oxygen during the heating process and causing a flash explosion, thereby ensuring the safety of the indigo sublimation process. In addition, an appropriate pressure is maintained during the indigo sublimation process to obtain a gaseous indigo of sufficient concentration.

[0072] The mixed gas is sprayed onto the wet cotton cloth. With the help of the force of the spray, the gaseous indigo in the mixed gas can penetrate into the fibers of the cotton cloth and then condense, thereby avoiding the indigo adhering only to the surface of the cotton cloth and obtaining a good dyeing depth; and the spray pressure, spray flow rate and the first vehicle speed of the mixed gas cooperate with each other, so that enough gaseous indigo can penetrate into the fibers of the cotton cloth for condensation, thereby improving the indigo dyeing effect of the cotton cloth, and the color depth of the cotton cloth is controllable.

[0073] The first dyed cloth is ultrasonically treated, and indigo is vibrated by ultrasonic waves of a suitable frequency, so that the indigo further diffuses and penetrates into the fibers of the cotton cloth, thereby improving the dyeing depth and dyeing uniformity; and while performing the ultrasonic treatment, water mist is sprayed on the ultrasonically treated area to increase the water content of the first dyed cloth, so that the indigo can further penetrate and diffuse into the fibers of the cotton cloth under the vibration of the ultrasonic wave; moreover, the water mist can form a water film between the first dyed cloth and the working area of ​​the ultrasonic vibrator, thereby reducing the friction between the cotton cloth and the ultrasonic vibrator and reducing the risk of damage to the cotton cloth; in addition, the water mist can also help cool the ultrasonic vibrator and extend the working life of the ultrasonic vibrator.

[0074] The second dyed cloth is subjected to steam jet treatment, and the high temperature of the steam and the force of the jet are used to heat the second dyed cloth evenly, so that the indigo can be fixed to the fibers of the cotton cloth, thereby improving the color fastness of the cotton cloth; at the same time, the moisture content of the second dyed cloth can be reduced, the difficulty of subsequent drying treatment can be reduced, and excess indigo on the surface of the second dyed cloth can be removed.

[0075] The third dyed cloth is dried by using hot air at a suitable temperature, which has high drying efficiency and less energy consumption, and can further improve the fixation of indigo and prevent fading.

[0076] By using the method of the present invention, the dyeing and finishing process is safe and reliable, the dyeing effect is good, the color fastness is excellent, and there is no need to reduce indigo to a leuco form, that is, the consumption of chemical reagents such as hydrosulfite and caustic soda is saved, and the generation of difficult-to-treat sulfur-containing alkaline colored wastewater is avoided, and the method has the characteristics of cleanliness and environmental protection; and in the method of the present invention, the mixed gas can also be recycled, which can save inert gas and indigo, and has the ability of sustainable development.

[0077] The above is a detailed introduction to the method for indigo dyeing of cotton cloth provided by an embodiment of the present invention. Specific examples are used herein to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for indigo dyeing of cotton cloth, characterized in that: The following steps are involved: Dyeing preparation: dip cotton cloth into a surfactant with a concentration of 3 to 10 g / L to form a wet cotton cloth, and control the rolling rate to be 100 to 150%; Indigo sublimation, in an inert gas environment, heating the indigo powder to sublimate to form a mixed gas, wherein the heating temperature of the indigo powder is in the range of 300 to 320°C; Desublimation dyeing, the mixed gas is guided out and sprayed evenly onto the wet cotton cloth to desublimate to form a first dyed cloth, and the spraying pressure of the mixed gas is in the range of 0.4-0.5 MPa; Ultrasonic treatment, using ultrasonic waves to treat the first dyed cloth to form a second dyed cloth, the frequency range of the ultrasonic treatment is 30 to 50 MHz; the first dyed cloth is slid along the working area surface of the ultrasonic vibrator so that the first dyed cloth is subjected to ultrasonic treatment; Steam jet treatment, using 130-140° C. steam to jet the second dyed cloth to form a third dyed cloth, the jet flow rate of the steam being in the range of 30-40 m / s; The third dyed cloth is dried using hot air at 110-120°C.

2. The method according to claim 1, characterized in that The surfactant is composed of one or more of fatty alcohol polyoxyethylene ether, sodium butylnaphthalene sulfonate and sulfosuccinate.

3. The method according to claim 1, characterized in that Before the desublimation dyeing, the temperature of the wet cotton cloth is controlled at 40-90°C.

4. The method according to claim 1, characterized in that The inert gas includes nitrogen, argon or helium.

5. The method according to claim 1, characterized in that The indigo sublimation pressure was maintained at 6×10 5 ~7×10 5 Pa.

6. The method according to claim 1, characterized in that The concentration of gaseous indigo in the mixed gas is in the range of 5 to 10 kg / m 3 .

7. The method according to claim 1, characterized in that The injection flow rate of the mixed gas is in the range of 1200 to 1800 ml / min.

8. The method according to claim 1, characterized in that While the ultrasonic treatment is being carried out, water mist is sprayed on the ultrasonic treatment area. The droplet size of the water mist is 200-300 μm, and the spraying flow rate of the water mist is 700-900 ml / min.

9. The method according to claim 1, characterized in that The following steps are also included: The wet cotton cloth passes through the spraying area of ​​the mixed gas at a first vehicle speed, wherein the first vehicle speed is 10 to 50 m / min; The first dyed fabric passes through the ultrasonic treatment area at a second speed, and the second speed is 25-35 m / min; The second dyed fabric passes through the steam jet treatment area at a third speed, and the third speed is 50-60 m / min; The third dyed cloth passes through the drying treatment area at a fourth speed, and the fourth speed is 10-20 m / min.

10. The method according to claim 1, characterized in that The dyeing preparation also includes pre-treatment of the cotton cloth, and the pre-treatment includes singeing, desizing, scouring, bleaching and mercerizing in sequence.

Images