Multistage dyeing method of cotton yarn
Through the combination of multi-level dyeing methods and innovative dyeing devices, the problem that dyes are difficult to penetrate into the fibers in traditional dyeing methods is solved, and a more uniform and deep dyeing effect is achieved, improving color fastness and product quality.
Patent Information
- Application Number
- CN202411659530.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-20
- Publication Date
- 2025-02-25
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
In traditional cotton yarn dyeing methods, it is difficult for dye to penetrate deep into the fiber, resulting in insufficient color fastness and uneven dyeing.
The multi-stage dyeing method is adopted, through pretreatment, dyeing, repeated dyeing and post-treatment steps, combined with the intermittently started dyeing device, the dynamic effects of the stirring rod and rotating disk are used to promote uniform distribution and deep penetration of dyes.
It significantly improves the penetration effect and dye uniformity of dyeing in cotton yarns, enhances the depth and color fastness of dyeing, reduces the frequency of repeated dyeing, and reduces water and energy consumption.
Smart Images
Figure CN119507140A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of dyeing methods, and more particularly to a multi-stage dyeing method for cotton yarn. Background Art
[0002] In the traditional cotton yarn dyeing process, cotton yarn often needs to go through multiple processing steps to ensure dyeing uniformity and color fastness, which steps usually include pretreatment (such as degreasing, bleaching), dyeing and post-treatment (such as fixing and softening).
[0003] Traditional cotton yarn dyeing usually adopts the static immersion method, that is, the cotton yarn is directly immersed in a dyeing tank containing the dye, and the dye is attached to the fiber by natural adsorption. In this process, the distribution of the dye depends on the diffusion ability of the dye itself and the natural absorbency of the fiber. There is often no additional mechanical or power assistance to promote the uniform distribution of the dye. Since static immersion relies on the natural diffusion of the dye, the dye molecules can only infiltrate the surface of the fiber and it is difficult to penetrate into the interior of the fiber. This surface dyeing makes the textiles easy to fade or have insufficient color fastness during washing and daily use.
[0004] Therefore, in view of the above-mentioned technical problems, it is necessary to provide a multi-stage dyeing method for cotton yarn. Summary of the invention
[0005] The object of the present invention is to provide a multi-stage dyeing method for cotton yarn to solve the above-mentioned problems.
[0006] In order to achieve the above purpose, the technical solution provided by an embodiment of the present invention is as follows:
[0007] A multi-stage dyeing method for cotton yarn comprises the following steps:
[0008] S1. Pretreatment: Thoroughly wash the cotton yarn to remove grease, impurities or additives in the preparation process to ensure that the yarn is suitable for receiving dyes;
[0009] S2, dyeing: placing the cleaned cotton yarn in a dyeing device, pouring the dyeing liquid into the dyeing device to ensure that the cotton yarn is completely immersed in the dye, and then intermittently starting the dyeing device for dyeing;
[0010] S3, repeat the operation: after the first dyeing is completed, the cotton yarn is thoroughly washed with clean water to remove excess dye, and the dyeing liquid is changed and step S2 is repeated, and a second dyeing is performed using a dye of a different color to produce a layered dyeing effect;
[0011] S4, subsequent dyeing: repeat step S2 for multiple dyeing as needed, and thoroughly wash the cotton yarn after each dyeing;
[0012] S5. Post-treatment: After all dyeing steps are completed, the dyed cotton yarn is subjected to color fixing and softening treatments, and finally dried.
[0013] As a further improvement of the present invention, the specific operation steps of S1 include:
[0014] S11: 0.5% to 1% of a nonionic surfactant and 0.2% of sodium carbonate are mixed in water controlled at a temperature of 30° C. to 40° C., and the pH value is adjusted to 9 to 10;
[0015] S12: Soak the cotton yarn in this cleaning solution for 15 to 20 minutes, stirring gently using a mechanical stirring device to promote uniform action of the cleaning agent and avoid fiber damage;
[0016] S13: Wash the cotton yarn at least three times, each time for not less than 5 minutes, to ensure that all detergents and loose impurities are thoroughly removed, and the last rinse is done in softened water to reduce the possible adverse effects of water hardness on the fiber.
[0017] As a further improvement of the present invention, the dyeing device in S2 includes a dyeing cylinder, a cover plate is movably installed on the top of the dyeing cylinder, and a valve is installed on the bottom of the dyeing cylinder, a servo motor is installed on the cover plate, a stirring rod is fixedly connected to the output end of the servo motor, and a limit block is installed at the bottom of the stirring rod.
[0018] As a further improvement of the present invention, the bottom end of the dyeing cylinder is rotatably connected to a rotating disk, a plurality of evenly distributed elastic strips are installed on the rotating disk, and a limiting groove matching the limiting block is opened in the middle of the top end of the rotating disk.
[0019] As a further improvement of the present invention, the elastic strip is surrounded by cotton yarn, and the elastic strip is made of silicone material.
[0020] As a further improvement of the present invention, active dyes are used as dyeing agents in S2, and the dyeing solution in S2 is prepared by dissolving the active dyes in water, adjusting the pH value to 9 to 11, and using sodium carbonate as a pH regulator.
[0021] As a further improvement of the present invention, the stirring rod in S2 is started intermittently, and the rotation rate of the stirring rod is set to 60 to 120 revolutions per minute to generate appropriate centrifugal force and liquid dynamics.
[0022] As a further improvement of the present invention, the dyeing temperature in S2 is between 60° C. and 80° C. to promote the reaction between the dye molecules and the cotton fibers; the dyeing time is controlled between 30 and 60 minutes and is adjusted according to the required color depth and color fastness.
[0023] As a further improvement of the present invention, the specific operation steps of S5 include:
[0024] S51: Fixation treatment: Use low-formaldehyde or formaldehyde-free fixing agent, add it to warm water at a mass ratio of 0.1% to 0.3%, soak the dyed cotton yarn in the fixing agent solution, control the temperature at 50℃ to 60℃, and last for 15 to 30 minutes to ensure that a stable chemical bond is formed between the dye and the fiber, and soak the dyed cotton yarn in the fixing agent solution, control the temperature at 50℃ to 60℃, and last for 15 to 30 minutes;
[0025] S52: Softening treatment: Add nonionic or cationic softener to the washed cotton yarn. The amount of softener is usually 1% to 2% of the fiber weight. The treatment temperature is maintained at 40°C to 50°C and the treatment time is 10 to 20 minutes.
[0026] S53: Drying: Dry the treated cotton yarn in a temperature-controlled environment using a hot air circulation drying method with the drying temperature controlled at 70°C to 90°C and the drying time being 1 to 3 hours.
[0027] As a further improvement of the present invention, the softener in S51 is a silicon-based softener, and the color fixing agent is a cationic color fixing agent.
[0028] Compared with the prior art, the advantages of the present invention are:
[0029] The multi-stage dyeing method adopted in this scheme significantly improves the penetration effect and dyeing uniformity of the dye in the cotton yarn through innovative dyeing devices and processes. By intermittently starting the synchronous rotation of the stirring rod and the rotating disk, the dynamic effect generated by the intermittent starting of the stirring rod leads to periodic flow and turbulence in the dyeing liquid. The dynamic flow helps the dye molecules to be more evenly distributed in the dyeing liquid, avoiding the problems of dye deposition and uneven dyeing. At the same time, the centrifugal force generated by the rotation of the stirring rod and the rotating disk can cause the dyeing liquid to apply greater pressure to the surface of the cotton yarn, which helps the dye molecules to penetrate the outer layer of the cotton yarn to reach the inner fiber. The effect of centrifugal force also causes the cotton yarn to undergo periodic tension and relaxation during rotation, which helps to open the micropores of the fiber, making it easier for the dye to enter the fiber, improving the dyeing depth and uniformity, and improving the dyeing depth and color fastness, thereby improving product quality while reducing the frequency of repeated dyeing and reducing water and energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 It is a schematic diagram of a multi-stage dyeing method for cotton yarn of the present invention;
[0031] Figure 2 It is a structural schematic diagram of the dyeing device of the present invention;
[0032] Figure 3 It is a schematic diagram of the initial structure of the dyeing device of the present invention;
[0033] Figure 4 It is a schematic diagram of the dyeing structure of the dyeing device of the present invention.
[0034] Description of the numbers in the figure:
[0035] 1. Dyeing cylinder; 3. Elastic strip. DETAILED DESCRIPTION
[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.
[0037] Example:
[0038] See also Figure 1-4 , a multi-stage dyeing method for cotton yarn, comprising the following steps:
[0039] S1. Pretreatment: Thoroughly wash the cotton yarn to remove grease, impurities or additives in the preparation process to ensure that the yarn is suitable for receiving dyes;
[0040] S2, dyeing: placing the cleaned cotton yarn in a dyeing device, pouring the dyeing liquid into the dyeing device to ensure that the cotton yarn is completely immersed in the dye, and then intermittently starting the dyeing device for dyeing;
[0041] S3, repeat the operation: after the first dyeing is completed, the cotton yarn is thoroughly washed with clean water to remove excess dye, and the dyeing liquid is changed and step S2 is repeated, and a second dyeing is performed using a dye of a different color to produce a layered dyeing effect;
[0042] S4, subsequent dyeing: repeat step S2 for multiple dyeing as needed, and thoroughly wash the cotton yarn after each dyeing;
[0043] S5. Post-treatment: After all dyeing steps are completed, the dyed cotton yarn is subjected to color fixing and softening treatments, and finally dried.
[0044] Among them, the multi-stage dyeing method adopted through innovative dyeing equipment and processes significantly improves the penetration effect and dyeing uniformity of the dye in the cotton yarn. By intermittently starting the synchronous rotation of the stirring rod and the rotating disk, the dynamic effect generated by the intermittent starting of the stirring rod leads to periodic flow and turbulence in the dyeing liquid. The dynamic flow helps the dye molecules to be more evenly distributed in the dyeing liquid, avoiding the problems of dye deposition and uneven dyeing. At the same time, the centrifugal force generated by the rotation of the stirring rod and the rotating disk can prompt the dyeing liquid to apply greater pressure to the surface of the cotton yarn, which helps the dye molecules to penetrate the outer layer of the cotton yarn to reach the inner fiber. The effect of centrifugal force also causes the cotton yarn to undergo periodic tension and relaxation during rotation, which helps to open the micropores of the fiber, making it easier for the dye to enter the fiber, improving the dyeing depth and uniformity, and improving the dyeing depth and color fastness, thereby improving product quality while reducing the frequency of repeated dyeing and reducing water and energy consumption.
[0045] S1 specific operation steps include:
[0046] S11: 0.5% to 1% of a nonionic surfactant and 0.2% of sodium carbonate are mixed in water controlled at a temperature of 30° C. to 40° C., and the pH value is adjusted to 9 to 10;
[0047] S12: Soak the cotton yarn in this cleaning solution for 15 to 20 minutes, stirring gently using a mechanical stirring device to promote uniform action of the cleaning agent and avoid fiber damage;
[0048] S13: Wash the cotton yarn at least three times, each time for not less than 5 minutes, to ensure that all detergents and loose impurities are thoroughly removed, and the last rinse is done in softened water to reduce the possible adverse effects of water hardness on the fiber.
[0049] Among them, non-ionic surfactants are used because of their mild effect on cotton fibers and good detergency, which are suitable for treating natural fibers. The concentration of non-ionic surfactants is set at 0.5% to 1%, which is enough to effectively remove grease and impurities but will not cause excessive chemical damage to the fibers.
[0050] Subsequently, 0.2% sodium carbonate is added to adjust the pH value of the solution to 9 to 10. Sodium carbonate plays a role in buffering and enhancing the cleaning effect, thereby improving the detergency of the surfactant. The temperature is controlled at 30°C to 40°C, which helps to activate the surfactant without causing excessive shrinkage or stretching of the cotton fibers.
[0051] Soak the cotton yarn in the prepared cleaning solution for 15 to 20 minutes to allow the cleaning agent to penetrate every fiber of the cotton yarn. Use a mechanical stirring device to gently stir it. The purpose of stirring is to ensure sufficient contact between the cleaning agent and the fiber, while avoiding fiber damage due to mechanical force during the stirring process.
[0052] The cotton yarn treated with detergent is washed at least three times, each time for no less than 5 minutes, to ensure that all detergents and loose impurities are completely removed, and rinsed with softened water for the last time. The use of softened water can reduce the hard water deposition caused by excessive minerals (such as calcium and magnesium ions) in the water.
[0053] The dyeing device in S2 includes a dyeing cylinder 1, a cover plate is movably installed on the top of the dyeing cylinder 1, a valve is installed on the bottom of the dyeing cylinder 1, a servo motor is installed on the cover plate, a stirring rod is fixedly connected to the output end of the servo motor, and a limit block is installed on the bottom of the stirring rod.
[0054] The bottom end of the dyeing cylinder 1 is rotatably connected to a rotating disk, on which a plurality of evenly distributed elastic strips 3 are mounted, and a limiting groove matching the limiting block is provided in the middle of the top end of the rotating disk.
[0055] The elastic strip 3 is surrounded by cotton yarn, and the elastic strip 3 is made of silicone material.
[0056] Among them, the dyeing cylinder 1 is the main container for loading cotton yarn, with a movable cover on the top to facilitate loading and unloading of cotton yarn, a valve installed at the bottom to control the inlet and outlet of dyeing liquid, and a servo motor installed on the cover to drive the stirring rod to stir the dyeing liquid, thereby ensuring uniform distribution of the dye and effective penetration of the cotton yarn.
[0057] The output end of the servo motor is fixedly connected to a stirring rod, which rotates inside the dyeing cylinder to help evenly distribute the dye. A limit block is installed at the bottom of the stirring rod to match the limit groove in the middle of the top of the rotating disk. This design ensures that the stirring rod can drive multiple elastic strips on the rotating disk to rotate synchronously.
[0058] The rotating disk is located at the bottom of the dyeing cylinder. Through the rotation connection with the dyeing cylinder, it can drive the elastic strips installed on it to rotate synchronously. The elastic strips 3 are evenly distributed on the rotating disk. The material is silicone, which has good elasticity and chemical stability. The elastic strips are wrapped around the cotton yarn. Through their fixed and elastic characteristics, the tension and position of the cotton yarn are kept stable during the dyeing process.
[0059] Through the intermittent start-up of the stirring rod and the rotating disk, the dyeing liquid and the cotton yarn produce dynamic movement under the action of centrifugal force. This dynamic includes the tension and relaxation of the cotton yarn and the impact fluctuation of the dyeing liquid, which helps to enhance the penetration rate of the dye into the cotton yarn and the dye absorption rate, thereby improving the dyeing efficiency and the quality of the final product.
[0060] The kinetic effect of the intermittent start-up of the stirring rod causes periodic flow and turbulence in the dyeing liquid. The dynamic flow helps the dye molecules to be more evenly distributed in the dyeing liquid, avoiding the problems of dye deposition and uneven dyeing. At the same time, the centrifugal force generated by the rotation of the stirring rod and the rotating disk can cause the dyeing liquid to apply greater pressure to the surface of the cotton yarn, helping the dye molecules to penetrate the outer layer of the cotton yarn to reach the inner fiber. The centrifugal force also causes the cotton yarn to undergo periodic tension and relaxation during rotation, which helps to open the micropores of the fiber, making it easier for the dye to enter the interior of the fiber, thereby improving the dyeing depth and uniformity.
[0061] The elastic strip provides necessary support and fixation for the cotton yarn, ensuring that it remains stable during high-speed rotation and preventing damage caused by friction or tearing. The rotating disk drives the rotation of the elastic strip, which will produce tiny fluctuations under intermittent start-up. The fluctuations help the dyeing liquid form a dynamic flow pattern on the surface and inside of the cotton yarn, further enhancing the dyeing effect.
[0062] Reactive dyes are used as dyeing agents in S2. The dyeing solution in S2 is prepared by dissolving the reactive dyes in water, adjusting the pH value to 9 to 11, and using sodium carbonate as a pH regulator.
[0063] The stirring rod in S2 is started intermittently, and the rotation rate of the stirring rod is set to 60 to 120 revolutions per minute to generate appropriate centrifugal force and liquid dynamics.
[0064] In S2, the dyeing temperature is between 60°C and 80°C to promote the reaction between the dye molecules and the cotton fibers; the dyeing time is controlled between 30 and 60 minutes and adjusted according to the required color depth and color fastness.
[0065] Among them, the reactive dye is accurately weighed and dissolved in an appropriate amount of water. The concentration of the reactive dye needs to be adjusted according to the final required color depth and the absorption capacity of the yarn. Sodium carbonate is used as a pH regulator to adjust the pH value of the solution to 9 to 11. Within this pH range, the reactive dye can react chemically with the cotton fiber more effectively, thereby improving the uniformity and color fastness of the dyeing. The correct pH value helps to fix the dye ions on the cotton fiber and enhance the durability of the dyeing.
[0066] The intermittent start-up of the stirring rod, which rotates at a speed of 60 to 120 revolutions per minute, can not only generate sufficient centrifugal force to promote the uniform penetration of the dye into the cotton fibers, but also avoid the accumulation of dye on the yarn through the generated liquid dynamics, thereby preventing uneven dyeing.
[0067] The dyeing temperature is controlled between 60℃ and 80℃ in order to promote the effective combination of active dye molecules and cotton fibers. The temperature higher than normal temperature helps to open the micropores of cotton fibers, making it easier for dye molecules to penetrate into the fibers. The dyeing time is controlled between 30 and 60 minutes, which can be adjusted according to the expected color depth and required color fastness to ensure that each strand of fiber fully absorbs the dye, while also ensuring a balance between economy and efficiency.
[0068] S5 specific operation steps include:
[0069] S51: Fixation treatment: Use low-formaldehyde or formaldehyde-free fixing agent, add it to warm water at a mass ratio of 0.1% to 0.3%, soak the dyed cotton yarn in the fixing agent solution, control the temperature at 50℃ to 60℃, and last for 15 to 30 minutes to ensure that a stable chemical bond is formed between the dye and the fiber, and soak the dyed cotton yarn in the fixing agent solution, control the temperature at 50℃ to 60℃, and last for 15 to 30 minutes;
[0070] S52: Softening treatment: Add nonionic or cationic softener to the washed cotton yarn. The amount of softener is usually 1% to 2% of the fiber weight. The treatment temperature is maintained at 40°C to 50°C and the treatment time is 10 to 20 minutes.
[0071] S53: Drying: Dry the treated cotton yarn in a temperature-controlled environment using a hot air circulation drying method with the drying temperature controlled at 70°C to 90°C and the drying time being 1 to 3 hours.
[0072] The softener in S51 is a silicon-based softener, and the fixing agent is a cationic fixing agent.
[0073] Among them, an environmentally friendly low-formaldehyde or formaldehyde-free cationic fixing agent is used. This fixing agent has significant advantages in environmental protection and user safety. The fixing agent is dissolved in warm water at a mass ratio of 0.1% to 0.3%, and the dyed cotton yarn is immersed therein. By controlling the water temperature at 50°C to 60°C and the soaking time for 15 to 30 minutes, this process not only fixes the colorant, but also reduces color loss during washing.
[0074] The color fixing treatment strengthens the bonding force between the dye and the cotton fiber, improves the color fastness of the finished product, and enables the textiles to maintain bright colors after multiple washings. At the same time, the use of environmentally friendly color fixing agents helps to improve the market competitiveness of the products and meet environmental protection standards.
[0075] Add 1% to 2% silicone-based softener to the washed cotton yarn, maintain the treatment temperature at 40°C to 50°C for 10 to 20 minutes. Silicone-based softener is selected for its excellent softness and durability, and is suitable for improving the feel and anti-static properties of cotton yarn. This operation can form a protective film on the surface of the cotton yarn, significantly improving the soft feel and wearing comfort of the fiber, while also helping to reduce static electricity problems in subsequent processing. The use of softener not only improves the consumer experience, but also extends the service life of textiles.
[0076] The cotton yarn that has been fixed and softened is dried in a temperature-controlled environment using hot air circulation drying with the temperature controlled at 70°C to 90°C for 1 to 3 hours. This drying method ensures uniform evaporation of moisture inside and outside the fiber, avoiding fiber damage caused by uneven drying. Hot air circulation drying can effectively control temperature and humidity, ensuring the quality and dimensional stability of the cotton yarn. The cotton yarn dried in this way has better shape retention and reduces shrinkage or deformation problems caused by improper drying.
[0077] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.
[0078] In addition, it should be understood that although the present specification is described according to embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that those skilled in the art can understand.
Claims
1. A multi-stage dyeing method for cotton yarn, characterized in that: The following steps are involved: S1. Pretreatment: Thoroughly clean the cotton yarn to remove grease, impurities or additives in the preparation process to ensure that the yarn is suitable for receiving dyes; S2. Dyeing: Place the cleaned cotton yarn in a dyeing device, pour the dyeing liquid into the dyeing device to ensure that the cotton yarn is completely immersed in the dye, and then start the dyeing device intermittently to dye; S3, repeat the operation: After completing the first dyeing, rinse the cotton yarn thoroughly with clean water to remove excess dye, and then change the dyeing solution and repeat step S2, using a different color dye for the second dyeing to produce a layered dyeing effect; S4, subsequent dyeing: repeat step S2 for multiple dyeing as needed, and thoroughly wash the cotton yarn after each dyeing; S5. Post-treatment: After all dyeing steps are completed, the dyed cotton yarn is subjected to color fixing and softening treatments, and finally dried.
2. The multi-stage dyeing method for cotton yarn according to claim 1, wherein: The specific operation steps of S1 include: S11: mixing 0.5% to 1% of a nonionic surfactant and 0.2% of sodium carbonate in water controlled at a temperature of 30° C. to 40° C., and adjusting the pH value to 9 to 10; S12: Soak the cotton yarn in this cleaning solution for 15 to 20 minutes, stirring gently using a mechanical stirring device to promote uniform action of the cleaning agent and avoid fiber damage; S13: Wash the cotton yarn at least three times, each time for not less than 5 minutes, to ensure that all detergents and loose impurities are thoroughly removed, and use softened water for the final rinse to reduce the adverse effects that water hardness may have on the fiber.
3. The multi-stage dyeing method for cotton yarn according to claim 1, wherein: The dyeing device in S2 comprises a dyeing drum (1), a cover plate movably mounted on the top of the dyeing drum (1), a valve mounted on the bottom of the dyeing drum (1), a servo motor mounted on the cover plate, a stirring rod fixedly connected to the output end of the servo motor, and a limit block mounted on the bottom end of the stirring rod.
4. The multi-stage dyeing method for cotton yarn according to claim 3, wherein: The bottom end of the dyeing drum (1) is rotatably connected to a rotating disk, a plurality of evenly distributed elastic strips (3) are installed on the rotating disk, and a limiting groove matching the limiting block is opened in the middle of the top end of the rotating disk.
5. The multi-stage dyeing method for cotton yarn according to claim 4, characterized in that: The elastic strip (3) is surrounded by cotton yarn, and the elastic strip (3) is made of silicone material.
6. The multi-stage dyeing method for cotton yarn according to claim 1, characterized in that: In the S2, a reactive dye is used as a dyeing agent. The dyeing solution in the S2 is prepared by dissolving the reactive dye in water, adjusting the pH value to 9 to 11, and using sodium carbonate as a pH regulator.
7. The multi-stage dyeing method for cotton yarn according to claim 1, characterized in that: The stirring rod in S2 is started in an intermittent manner, and the rotation rate of the stirring rod is set to 60 to 120 revolutions per minute to generate appropriate centrifugal force and liquid dynamics.
8. The multi-stage dyeing method for cotton yarn according to claim 1, characterized in that: In the S2, the dyeing temperature is between 60° C. and 80° C. to promote the reaction between the dye molecules and the cotton fibers; the dyeing time is controlled between 30 and 60 minutes and is adjusted according to the required color depth and color fastness.
9. The multi-stage dyeing method for cotton yarn according to claim 1, characterized in that: The specific operation steps of S5 include: S51: Fixation treatment: Use a low-formaldehyde or formaldehyde-free fixing agent, add it to warm water at a mass ratio of 0.1% to 0.3%, soak the dyed cotton yarn in the fixing agent solution, control the temperature at 50℃ to 60℃, and last for 15 to 30 minutes to ensure the formation of a stable chemical bond between the dye and the fiber, soak the dyed cotton yarn in the fixing agent solution, control the temperature at 50℃ to 60℃, and last for 15 to 30 minutes; S52: Softening treatment: Add nonionic or cationic softener to the cleaned cotton yarn. The amount of softener is usually 1% to 2% of the fiber weight. The treatment temperature is maintained at 40℃ to 50℃ and the treatment time is 10 to 20 minutes. S53: Drying: Dry the treated cotton yarn in a temperature-controlled environment using a hot air circulation drying method with the drying temperature controlled at 70°C to 90°C for 1 to 3 hours.
10. The multi-stage dyeing method for cotton yarn according to claim 9, characterized in that: The softener in S51 is a silicon-based softener, and the color fixing agent is a cationic color fixing agent.