Low-energy dyeing process for polyester knitted fabric

Abstract

The application belongs to the technical field of textiles, and particularly relates to a low-energy-consumption dyeing process for polyester knitted fabric. The low-energy-consumption dyeing process for polyester knitted fabric comprises the following steps: S1, pretreatment: pretreating the polyester knitted fabric to remove surface impurities; S2, low-bath-ratio dyeing: immersing the pretreated fabric into prepared dye bath to complete preliminary adsorption of dyes; S3, sectional temperature-increasing dyeing: gradient temperature-increasing of the dye bath to realize dyeing; S4, ultrasonic-assisted treatment: synchronously starting an ultrasonic device at a specific stage of the sectional temperature-increasing dyeing; S5, UV-hot-air composite low-temperature color fixing: color fixing treatment of the dyed fabric; S6, low-concentration reduction cleaning: cleaning of the color-fixed fabric to remove surface floating color; S7, energy-saving post-treatment: subsequent finishing of the cleaned fabric; and S8, quality-based wastewater recycling: quality-based treatment of wastewater generated in each process and recycling.

Description

Technical Field

[0001] This application belongs to the field of textile technology, and in particular relates to a low-energy dyeing process for polyester knitted fabrics. Background Technology

[0002] Polyester knitted fabrics are widely used in clothing, home textiles, and other fields due to their advantages such as high strength, good elasticity, and wear and wash resistance. Their dyeing process mainly relies on disperse dyes and high-temperature, high-pressure dyeing. However, existing technologies have several problems: traditional polyester dyeing bath ratios are generally 1:5-1:10, resulting in high water consumption; high-temperature dyeing and high-temperature baking and color fixing processes require a large amount of steam, leading to low energy efficiency. Furthermore, during dyeing, wastewater from various processes is mixed and treated, resulting in complex compositions, high treatment difficulty, and a reuse rate typically below 30%. Pretreatment using strong alkalis and high-concentration reducing cleaning leads to high COD values ​​in the wastewater, resulting in high environmental treatment costs. Improvements are needed in these areas. Summary of the Invention

[0003] The purpose of this application is to provide a low-energy dyeing process for polyester knitted fabrics that can solve the above-mentioned problems.

[0004] The purpose of this application is to provide a low-energy dyeing process for polyester knitted fabrics, including the following steps: S1. Pretreatment: Pretreatment of polyester knitted fabric to remove surface impurities; S2, Low liquor ratio dyeing: The pre-treated fabric is immersed in the prepared dye bath to complete the initial adsorption of dye; S3. Segmented heating and dyeing: The dye bath is heated in a gradient to achieve dye uptake; S4. Ultrasonic-assisted treatment: The ultrasonic device is turned on simultaneously during specific stages of segmented heating and staining. S5, UV-Hot Air Composite Low Temperature Color Fixing: Color fixing treatment for dyed fabrics; S6. Low-concentration reduction cleaning: Clean the fabric after color fixing to remove surface loose dye; S7. Energy-saving post-treatment: Further finishing of the cleaned fabric; S8. Separate wastewater recycling: Wastewater generated from each process is treated separately and then reused.

[0005] Furthermore, the pretreatment adopts a compound system of dilute alkaline solution and low-foaming surfactant. The concentration of NaOH in the dilute alkaline solution is 2-3 g / L, and the low-foaming surfactant is JH-101 type, with an addition amount of 0.5 g / L. The solution is treated at a constant temperature of 80-85℃ for 20 min. After draining, the solution is rinsed once with 70℃ clean water, and then neutralized to pH 6-7 with 1% acetic acid solution to remove oil, sizing agent and oligomers from the fabric surface.

[0006] Furthermore: the liquor ratio of the low liquor ratio dyeing is controlled at 1:2.5-1:3. JH-RP60 type low foaming leveling agent is added to the dye bath at a dosage of 1g / L. The pH value of the dye bath is adjusted to 4.5-5.0. Disperse dye is added at a dosage of 1%-3% of the fabric weight. After stirring evenly, the pretreated fabric is immersed in the dye bath.

[0007] Furthermore, the segmented temperature-increasing staining adopts a gradient temperature-increasing mode: Hold at room temperature for 5 minutes, then increase the temperature to 85°C at a rate of 2°C / min and hold for 10 minutes. Then raise the temperature to 110℃ at a rate of 1℃ / min and hold for 15min; Finally, increase the temperature to 130℃ at a rate of 1.5℃ / min and hold for 30-60 minutes.

[0008] Furthermore, the ultrasonic-assisted treatment corresponds to the 85°C and 110°C holding stages of the segmented heating and staining process, and the power density of the ultrasonic device is controlled to be 0.5-1 W / cm². 2 The processing time per cycle is 60-120 seconds.

[0009] Furthermore, the specific operation of the UV-hot air composite low-temperature color fixing includes: immersing the dyed fabric in a color fixing solution containing color fixing agent DF-301 at a concentration of 20 g / L; after squeezing dry, the fabric is first subjected to a wavelength of 365 nm and an energy density of 200-250 mJ / cm². 2 After UV irradiation treatment, it is then baked in a 125-130℃ hot air oven for 2-4 minutes.

[0010] Furthermore, the low-concentration reduction cleaning system uses a sodium hydrosulfite system with a sodium hydrosulfite content of 5 g / L and a sodium carbonate content of 3 g / L. The treatment temperature is controlled below 80°C, and the treatment time is 15 min.

[0011] Furthermore, the specific operation of the separate wastewater recycling includes: treating the oil removal wastewater generated in the pretreatment, the dyeing and cleaning wastewater generated in the dyeing process, and the wastewater generated in the reduction and cleaning process by filtration, adsorption, and membrane separation, respectively. The pretreatment wastewater is recycled to the pretreatment process after treatment, and the dyeing and cleaning wastewater is recycled to the low-liquor-ratio dyeing and rinsing stages of each process after treatment.

[0012] The beneficial effects of this application are: 1. This application uses a pretreatment system of dilute alkali compounding, low bath ratio dyeing, and wastewater recycling design to reduce the consumption of water resources and chemical agents, reduce the pollutant content of wastewater, alleviate the pressure of environmental protection, and avoid damage to polyester fibers by high alkali and high concentration agents, thus taking into account both environmental protection and fiber protection. 2. By using segmented heating mode, ultrasonic-assisted treatment and UV-hot air composite low-temperature color fixing process, the dyeing uniformity is effectively improved, and dyeing defects such as color spots and color variations are reduced. At the same time, it avoids problems such as poor fabric hand feel and heat yellowing caused by high temperature treatment, improves the fabric elasticity recovery rate, reduces pilling and fuzzing, and ensures dyeing quality and overall fabric performance. 3. The process of this application is seamlessly connected. The staged ultrasonic assistance and UV irradiation shorten the fixing and heat preservation time, optimize the production process, improve production efficiency, and the application of formaldehyde-free fixing agent meets the environmental protection requirements of high-end clothing and is suitable for the dyeing needs of conventional polyester fibers, making it highly practical. Detailed Implementation

[0013] The technical solutions in the embodiments of this application will be clearly described below with reference to the examples. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0014] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those shown or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0015] The low-energy dyeing process for polyester knitted fabrics provided in this application will be described in detail through specific embodiments and application scenarios. Example 1:

[0016] In the embodiments of this application, an overflow dyeing machine or an airflow dyeing machine is used for continuous pretreatment. Specifically, the polyester knitted fabric is passed through a pretreatment tank at a speed of 10-15 m / min. The tank contains a mixture of 2-3 g / L NaOH dilute alkaline solution and 0.5 g / L JH-101 type low-foaming surfactant, and the temperature in the tank is controlled at 80-85°C. After the fabric is soaked for 20 minutes, it is rinsed once in a 70°C clean water rinsing tank, and then neutralized by a 1% acetic acid spraying device. The pH value of the fabric at the outlet is monitored in real time until it reaches 6-7. Finally, excess water is removed by a wringer.

[0017] In this application, the above-mentioned method can remove impurities and protect fibers. The concentration of dilute alkali is significantly reduced compared to traditional pretreatment, effectively avoiding hydrolytic damage to polyester fibers caused by high alkali. At the same time, the low-foaming surfactant can quickly penetrate the gaps in the fabric and efficiently remove oils, sizing agents, and oligomers. It can also reduce water consumption and chemical residues. The low-foaming characteristic avoids foam from hindering chemical contact, and only one rinsing is needed to reduce surfactant residues. Combined with acetic acid neutralization to control pH, it provides a stable fiber surface environment for subsequent dyeing processes and reduces the problem of uneven dyeing caused by pH fluctuations in the dye bath. In addition, it can also reduce the wastewater treatment load. The dilute alkali system reduces the alkalinity of the wastewater, and the low concentration of chemical residues reduces the COD value of subsequent wastewater, laying the foundation for the recycling of wastewater. Example 2:

[0018] This application provides a low-energy dyeing process for polyester knitted fabrics. In addition to the above-mentioned technical features, the low-energy dyeing process for polyester knitted fabrics in this application also includes the following technical features.

[0019] In this embodiment, a high-temperature and high-pressure dyeing machine is selected. The total amount of dye bath is calculated according to the weight of the fabric. First, 1g / L of JH-RP60 low-foaming leveling agent is added. The pH of the dye bath is adjusted to 4.5-5.0 with acetic acid. Then, disperse dye is added at 1%-3% owf. The stirring device is turned on and the speed is 30-50r / min to ensure that the dye is fully dispersed. Then, the pretreated fabric is put into the dye bath and soaked at room temperature for 5 minutes to complete the initial adsorption.

[0020] In this application, the above-mentioned method has significant water and energy saving effects. The liquor ratio is reduced from the traditional 1:5-1:10 to 1:2.5-1:3, reducing water consumption. At the same time, the reduction in the total amount of dye bath reduces energy consumption during the heating stage. In addition, it can improve the leveling properties and avoid foaming interference. JH-RP60, as a high-concentration, low-foaming leveling agent, has a unique molecular structure that combines slow dyeing and migration dyeing functions. An addition of 1g / L can avoid color shift caused by excessive auxiliaries. Combined with a weakly acidic environment of pH 4.5-5.0, it effectively prevents dye aggregation and improves dye utilization. At a low liquor ratio, the dye concentration is relatively concentrated, the fabric and dye liquor come into more sufficient contact, the dyeing rate is improved, and dye waste and subsequent floating color treatment pressure are reduced. Example 3:

[0021] This application provides a low-energy dyeing process for polyester knitted fabrics. In addition to the above-mentioned technical features, the low-energy dyeing process for polyester knitted fabrics in this application also includes the following technical features.

[0022] In this embodiment, based on the programmed temperature rise function of the high-temperature and high-pressure dyeing machine, a three-stage temperature rise curve is set: 1. Maintain room temperature of 25°C for 5 minutes to allow the dye to be evenly adsorbed onto the fabric surface; 2. Increase the temperature to 85°C at a rate of 2°C / min and hold for 10 minutes; 3. Slowly increase the temperature to 110°C at a rate of 1°C / min and hold for 15 minutes; 4. Increase the temperature to 130°C at a rate of 1.5°C / min and hold for 30-60 minutes. The holding time is adjusted according to the fabric thickness to ensure that the dye fully penetrates into the fiber.

[0023] In this application, the 85℃ heat preservation stage utilizes the fiber swelling effect to assist dye diffusion. The slow heating at 110℃ avoids color differences between the inner and outer layers caused by rapid dyeing and also reduces dyeing defects. The gradient heating mode avoids dye aggregation and color spot problems caused by traditional uniform heating. In addition, the 130℃ heat preservation temperature is more suitable for conventional polyester fibers than the 100℃ low-temperature dyeing of modified polyester and can also shorten the total dyeing time.

[0024] Furthermore, in this embodiment, a trough-type ultrasonic generator is installed inside the high-temperature, high-pressure dyeing machine, and the power density is adjusted to 0.5-1 W / cm². 2 It is activated only during the 85℃ and 110℃ heat treatment stages, with a single treatment time of 60-120 seconds. The ultrasonic wave direction is perpendicular to the fabric's running direction to ensure uniform irradiation. The cavitation effect of the ultrasound can disrupt the fiber surface boundary layer, reducing dye diffusion resistance. It also enhances agent penetration during the 85℃ fiber swelling stage and accelerates dye entry into the fiber crystallization zone during the 110℃ stage, increasing the dyeing rate. The power density is 0.5-1 W / cm². 2 It can avoid fiber damage, and with the phased opening, it reduces the dye concentration difference between the inner and outer layers of the fabric, improves the dyeing depth, and the ultrasonic assistance can shorten the 130℃ heat preservation time to 30 minutes, further reducing energy consumption. Example 4:

[0025] This application provides a low-energy dyeing process for polyester knitted fabrics. In addition to the above-mentioned technical features, the low-energy dyeing process for polyester knitted fabrics in this application also includes the following technical features.

[0026] In this embodiment, a continuous color-fixing production line is used: 1. The fabric is dipped in a color-fixing solution containing 20g / L DF-301 color-fixing agent using a padding mill, with the roll-off rate controlled at 70%-80%. 2. The fabric then enters a UV irradiation chamber using UV lamps with a wavelength of 365nm and an energy density of 200-250mj / cm². 2Irradiation time: 30-40 seconds. 3. Immediately transfer to a hot air oven, control the temperature at 125-130℃, and bake for 2-4 minutes, maintaining a fabric running speed of 10m / min. The 125-130℃ baking temperature reduces energy consumption compared to traditional high-temperature baking, while avoiding issues like fabric hardening and yellowing caused by high temperatures, and improving fabric elasticity recovery. UV irradiation promotes the cross-linking reaction between the DF-301 fixing agent and the dye and fiber, thus shortening the subsequent hot air baking time. Low-temperature fixing reduces the volatilization of the fixing agent; the DF-301 fixing agent is formaldehyde-free, avoiding formaldehyde residue and better meeting the environmental protection requirements for children's wear and high-end apparel. Example 5:

[0027] This application provides a low-energy dyeing process for polyester knitted fabrics. In addition to the above-mentioned technical features, the low-energy dyeing process for polyester knitted fabrics in this application also includes the following technical features.

[0028] In this embodiment, a low-concentration reducing cleaning solution is prepared in the cleaning tank: 5 g / L sodium hydrosulfite + 3 g / L sodium carbonate. The temperature is controlled at 75-80℃, and the fabric is soaked for 15 minutes. A counter-current cleaning method is adopted, with the cleaning solution circulating from the rear section to the front section. Finally, it is rinsed twice with 60℃ clean water. This counter-current cleaning method can reduce the consumption of chemical agents and wastewater pollution. The amount of sodium hydrosulfite used is reduced compared to traditional processes, the amount of sodium carbonate used is reduced, and the COD value of the wastewater decreases, which is more in line with the environmental protection trend of acidic reducing cleaning. At the same time, using a treatment temperature below 80℃ can prevent the loss of polyester fiber strength caused by high temperature and reduce the impact of reduction on the color of dyes. Example 6:

[0029] This application provides a low-energy dyeing process for polyester knitted fabrics. In addition to the above-mentioned technical features, the low-energy dyeing process for polyester knitted fabrics in this application also includes the following technical features.

[0030] In this embodiment, a waste heat recovery setting machine is used: 1. The fabric first passes through a pre-drying zone, where the waste heat from the reduction cleaning wastewater treatment removes surface moisture; 2. It then enters the setting zone, where the temperature is controlled at 150-160℃ and the setting time is 30-40 seconds; 3. It passes through a cold air cooling zone, where the cooling air comes from the waste gas of the setting machine for heat exchange, simultaneously cooling the fabric to room temperature, and finally undergoes pre-shrinking finishing. This further reduces energy consumption, improves the overall performance of the fabric, avoids fiber thermal aging, reduces pilling and fuzzing, and shortens the production cycle.

[0031] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0032] The embodiments of this application have been described above, but this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A low-energy dyeing process for polyester knitted fabrics, characterized in that: Includes the following steps: S1. Pretreatment: Pretreatment of polyester knitted fabric to remove surface impurities; S2, Low liquor ratio dyeing: The pre-treated fabric is immersed in the prepared dye bath to complete the initial adsorption of dye; S3. Segmented heating and dyeing: The dye bath is heated in a gradient to achieve dye uptake; S4. Ultrasonic-assisted treatment: The ultrasonic device is turned on simultaneously during specific stages of segmented heating and staining. S5, UV-Hot Air Composite Low Temperature Color Fixing: Color fixing treatment for dyed fabrics; S6. Low-concentration reduction cleaning: Clean the fabric after color fixing to remove surface loose dye; S7. Energy-saving post-treatment: Further finishing of the cleaned fabric; S8. Separate wastewater recycling: Wastewater generated from each process is treated separately and then reused.

2. The low-energy dyeing process for polyester knitted fabric according to claim 1, characterized in that: The pretreatment uses a mixture of dilute alkaline solution and low-foaming surfactant. The concentration of NaOH in the dilute alkaline solution is 2-3 g / L, and the low-foaming surfactant is JH-101 type, with an addition amount of 0.5 g / L. The solution is treated at a constant temperature of 80-85℃ for 20 min. After draining, the solution is rinsed once with 70℃ clean water, and then neutralized to pH 6-7 with 1% acetic acid solution to remove oil, sizing agents and oligomers from the fabric surface.

3. The low-energy dyeing process for polyester knitted fabric according to claim 1, characterized in that: The liquor ratio for low liquor ratio dyeing is controlled at 1:2.5-1:

3. JH-RP60 low foaming leveling agent is added to the dye bath at a dosage of 1g / L. The pH value of the dye bath is adjusted to 4.5-5.

0. Disperse dye is added at a dosage of 1%-3% of the fabric weight. After stirring evenly, the pretreated fabric is immersed in the dye bath.

4. The low-energy dyeing process for polyester knitted fabric according to claim 1, characterized in that: The segmented temperature-increasing staining method employs a gradient temperature increase mode: Hold at room temperature for 5 minutes, then increase the temperature to 85°C at a rate of 2°C / min and hold for 10 minutes. Then raise the temperature to 110℃ at a rate of 1℃ / min and hold for 15min; Finally, increase the temperature to 130℃ at a rate of 1.5℃ / min and hold for 30-60 minutes.

5. The low-energy dyeing process for polyester knitted fabric according to claim 1, characterized in that: The ultrasonic-assisted treatment corresponds to the 85℃ and 110℃ holding stages of the segmented temperature-raising staining process, with the power density of the ultrasonic device controlled at 0.5-1 W / cm². 2 The processing time per cycle is 60-120 seconds.

6. The low-energy dyeing process for polyester knitted fabric according to claim 1, characterized in that: The specific operation of the UV-hot air composite low-temperature color fixing includes: immersing the dyed fabric in a color fixing solution containing color fixing agent DF-301 at a concentration of 20g / L; after squeezing out the dryness, the fabric is first subjected to a wavelength of 365nm and an energy density of 200-250mj / cm². 2 After UV irradiation treatment, it is then baked in a 125-130℃ hot air oven for 2-4 minutes.

7. The low-energy dyeing process for polyester knitted fabric according to claim 1, characterized in that: The low-concentration reduction cleaning system uses a sodium hydrosulfite system with a sodium hydrosulfite content of 5 g / L and a sodium carbonate content of 3 g / L. The treatment temperature is controlled below 80℃, and the treatment time is 15 min.

8. The low-energy dyeing process for polyester knitted fabric according to claim 1, characterized in that: The specific operation of the separate wastewater recycling includes: treating the oil removal wastewater generated in the pretreatment, the dyeing and cleaning wastewater generated in the dyeing process, and the wastewater generated in the reduction and cleaning process by filtration, adsorption, and membrane separation, respectively. The pretreatment wastewater is recycled to the pretreatment process after treatment, and the dyeing and cleaning wastewater is recycled to the low-liquor-ratio dyeing and rinsing stages of each process after treatment.