A dyeing and preshrinking method

Abstract

This application discloses a dyeing pre-shrinking method, relating to the field of dyeing technology. The pre-shrinking method includes the following steps: S1: Based on the material type and characteristics of the textile fabric to be treated, a corresponding dedicated pre-shrinking process is selected for pre-shrinking treatment before dyeing, fully eliminating residual internal stress and potential shrinkage within the fibers; S2: After the pre-shrinking treatment is completed, the textile fabric is dyed within a preset time limit to stabilize the dimensional state of the pre-shrinked fabric and maintain the dimensional stability effect of the pre-shrinked fabric. This pre-shrinking method can completely eliminate internal stress in the fibers before dyeing, avoiding uneven dyeing and color difference problems caused by uneven subsequent shrinkage, and reducing the color difference rate of the fabric. At the same time, it fully releases the potential shrinkage of the fibers, reduces the shrinkage rate, and significantly improves dimensional stability and finished product qualification rate. Furthermore, this technology enables continuous operation of pre-shrinking and dyeing, eliminating subsequent mechanical shrinkage processes, reducing production energy consumption, and eliminating the need for chemical setting, making it more environmentally friendly and ensuring the fabric's hand feel.

Description

Technical Field

[0001] This application relates to the field of dyeing technology, and in particular to a dyeing pre-shrinking method. Background Technology

[0002] In textile dyeing processes, yarns or fabrics inevitably accumulate internal stress and potential shrinkage during the preceding spinning and weaving stages. Traditional dyeing processes generally adopt a "dye first, shrink later" approach, where the fabric absorbs dye before undergoing shrinkage treatment. This method easily leads to uneven fabric shrinkage and unsatisfactory shrinkage results, which in turn cause problems such as uneven dyeing, color differences, and discrepancies in finished product dimensions, directly increasing the fabric scrap rate and affecting production efficiency.

[0003] Traditional dyeing post-treatment processes have many limitations, mainly including three methods: First, mechanical shrinkage after dyeing, which uses rollers and tenter frames to mechanically compress the dyed fabric, but the cured dye will hinder fiber shrinkage, resulting in limited shrinkage rate; Second, chemical setting treatment, which uses resins and cross-linking agents to set the fabric, but may damage the original feel of the fabric and pose environmental risks; Third, stepwise wet heat treatment, which involves steam treatment and drying in stages after dyeing, which not only has high energy consumption but also reduces production efficiency.

[0004] Post-dyeing shrinkage hinders fiber shrinkage due to dye adsorption, making it difficult to guarantee fabric dimensional stability. Chemical setting treatments can introduce harmful substances, failing to meet environmentally friendly production requirements. Stepwise wet heat treatment processes are complex, cumbersome, and result in high energy consumption and production costs. While the industry has recognized the importance of pre-shrinking before dyeing, related technologies largely focus on post-dyeing treatments, with a lack of systematic research on pre-shrinking before dyeing, making it difficult to meet the demands for efficient, environmentally friendly, and high-quality production. Summary of the Invention

[0005] The purpose of this application is to solve the problems mentioned in the background art, such as uneven dyeing, color difference, and mismatch of finished product size caused by fabric shrinkage after dyeing, which directly increases the fabric scrap rate and affects production efficiency. This application provides a dyeing pre-shrinking method.

[0006] To achieve the above objectives, this application specifically adopts the following technical solution:

[0007] A staining pre-shrinking method, the pre-shrinking method comprising the following steps:

[0008] S1: Based on the material type and characteristics of the textile fabric to be treated, select the corresponding special pre-shrinking process for pre-shrinking treatment before dyeing to fully eliminate residual internal stress and potential shrinkage in the fiber.

[0009] S2: After the pre-shrinking treatment is completed, the textile fabric is dyed within a preset time limit to stabilize the size of the pre-shrinked fabric and maintain the stability of the pre-shrinked size.

[0010] By adopting the above technical solution, pre-shrinking is performed according to the material before dyeing, which solves the problems of uneven shrinkage, uneven dyeing, and dimensional deviation caused by traditional fabric shrinkage after dyeing. It can effectively eliminate internal stress in fibers, stabilize fabric dimensions, and ensure dyeing effect.

[0011] Furthermore, in step S1, when the textile to be processed is a polyester / viscose blended yarn, a vacuum-controlled humidification setting process is used for pre-shrinking treatment.

[0012] By adopting the above technical solution, the pre-shrinking process is limited to a vacuum-cooled humidification setting process, which enables targeted treatment of yarn-type textiles, adapts to the structural form of packaged yarns, and solves the problems of color difference between inner and outer layers and incomplete shrinkage caused by the difference in shrinkage rate of different fibers in blended yarns.

[0013] Furthermore, the vacuum humidification setting process specifically involves placing the yarn bobbin inside the vacuum humidification setting equipment. The equipment is first evacuated to a vacuum degree of ≤10Pa, and then 85%RH humidification steam is injected into the chamber. The yarn is then kept at a constant temperature of 40-60℃ for 30 minutes to allow the steam to fully penetrate the yarn.

[0014] By adopting the above technical solution, key process parameters such as vacuum degree, humidity, temperature, and heat preservation time of vacuum conditioning and humidification setting are limited to ensure that the humidification steam fully penetrates the yarn interior, accurately and thoroughly eliminates the internal stress accumulated during spinning and weaving, ensures uniform and stable pre-shrinking effect, and provides a dimensionally stable yarn substrate for subsequent dyeing.

[0015] Furthermore, in step S1, when the textile fabric to be processed is a knitted elastic fabric or a general fabric, it is processed using an integrated pre-shrinking system for an airflow dyeing machine. The pre-shrinking system includes a humidification unit, a fabric tension regulating roller, and a condensate recovery unit.

[0016] By adopting the above technical solution, the pre-shrinking system of the limited airflow dyeing machine is integrated to realize the integrated connection between the pre-shrinking and dyeing equipment, simplify the process flow, and improve production efficiency and reduce process connection costs by integrating humidification, tension adjustment and condensate recovery functions.

[0017] Furthermore, the humidification unit is a steam injection device, which is equipped with a tungsten carbide nozzle with a nozzle orifice diameter of 0.5 mm, injects saturated steam at a pressure of 0.2-0.4 MPa, and the steam injection angle is set to 30°.

[0018] By adopting the above technical solutions, the structural and process parameters of the steam jet device, such as nozzle material, orifice diameter, jet pressure, and angle, are limited to ensure that steam acts uniformly and stably on the fabric surface, thereby improving steam penetration efficiency and pre-shrinking uniformity. The use of tungsten carbide material improves the wear resistance of the nozzle, extends the service life of the equipment, and ensures long-term production stability.

[0019] Furthermore, the humidification unit is an ultrasonic atomizing humidifier.

[0020] By adopting the above technical solution, an ultrasonic atomizing humidifier is provided as an alternative humidification solution. It uses ultrasonic atomization to generate finer moist steam, making the fabric absorb moisture more evenly. It is suitable for moisture-sensitive knitted elastic fabrics, further improving the adaptability and uniformity of pre-shrinking treatment and enriching the application scenarios of this technology.

[0021] Furthermore, the fabric is conveyed to the steam treatment zone at a constant speed of 20m / min, and the pre-shrinkage rate of the fabric is controlled within the range of 3%-5% by the precise control of the fabric tension regulating roller.

[0022] By adopting the above technical solution, the control parameters of fabric conveying speed and shrinkage rate are limited, the pre-shrinkage amount of the fabric is precisely controlled, and the shrinkage rate deviation is controlled within a very small range, thereby improving the finished product qualification rate.

[0023] Furthermore, the condensate formed after steam condensation is used to wet the gaps between fabric fibers, improve dyeing uniformity, and the condensate is recycled by the condensate recovery unit.

[0024] By adopting the above technical solutions, the condensate can be recovered and recycled, and the condensate can be used to wet the gaps between fabric fibers, thereby improving the uniformity of subsequent dye adsorption and reducing color difference. It can also realize the recycling of water resources, reduce production energy consumption and costs, and take into account both process effect and environmental protection and energy conservation requirements.

[0025] In summary, this application includes at least one of the following beneficial effects;

[0026] 1. According to this application, the pre-shrinking method can improve dyeing uniformity and reduce color difference. Pre-shrinking before dyeing can completely eliminate internal stress in fibers, avoid uneven dyeing and color difference caused by uneven shrinkage after dyeing, reduce the color difference rate of the fabric to below 0.5%, and solve the problem of color difference between the inner and outer layers of the yarn package.

[0027] 2. According to this application, the pre-shrinking method can improve dimensional stability and increase the yield. By pre-shrinking, the potential shrinkage of the fibers is fully released, and the fabric shrinkage rate deviation is controlled within ±1%, eliminating the problem of inconsistent finished product size. The fabric yield is increased by more than 15%, and the scrap rate is significantly reduced.

[0028] 3. According to this application, the pre-shrinking method can simplify the process and reduce energy consumption. By making the pre-shrinking and dyeing continuous, it eliminates complex processes such as mechanical shrinking after dyeing and step-by-step wet heat treatment, reducing production energy consumption by 30% and avoiding environmental and hand feel problems caused by chemical setting.

[0029] 4. This application, through the transition chamber unit, allows for a gradual transition process to the pre-shrinked yarn. This prevents the pre-shrinked yarn from directly contacting the ambient, dry air. It also avoids the yarn being suddenly exposed to a low-temperature, low-humidity environment after pre-shrinking, which could cause the fibers to shrink or spring back due to a rapid drop in temperature and rapid moisture loss. The transition chamber achieves a smooth transition in temperature and humidity, effectively maintaining the stable state of the fibers after pre-shrinking, thus ensuring that the dimensions and performance of the yarn and fabric maintain the expected results.

[0030] 5. In this application, during the humidification process in the transition chamber, a servo motor is started to drive the first reciprocating screw to rotate, thereby driving the distribution pipe to oscillate back and forth inside the transition chamber. This causes the nozzle to move evenly along the axial direction of the transition chamber, allowing the humidifying steam to diffuse evenly to all areas inside the transition chamber. This avoids situations where the humidity is too high or too low in certain areas, ensuring that the temperature and humidity in each area of ​​the chamber can change evenly and smoothly. This allows all yarns to obtain a consistent transition treatment effect, avoiding localized abnormal shrinkage caused by uneven temperature gradients, and further ensuring the stability of the overall pre-shrinking treatment.

[0031] 6. In this application, during the swinging process of the first reciprocating screw driving the diverter tube, the second reciprocating screw is rotated under the action of the transmission wheel and transmission belt, thereby driving the baffle to move back and forth inside the transition chamber, stirring the humidifying steam in the transition chamber, avoiding the accumulation of steam in local areas of the chamber, improving the uniformity of temperature and humidity in the chamber, ensuring the uniformity of the smooth transition of temperature and humidity, and further improving the stability of the yarn state after pre-shrinking. Attached Figure Description

[0032] Figure 1 This is a flowchart illustrating the pre-shrinking method in this application;

[0033] Figure 2 This is a three-dimensional structural diagram of the vacuum humidification shaping equipment in this application;

[0034] Figure 3 This is a schematic diagram of the first internal structure of the transition compartment in this application;

[0035] Figure 4 This is a schematic diagram of the second internal structure of the transition compartment in this application;

[0036] Figure 5 This is a partial disassembly diagram of the transition compartment in this application;

[0037] Figure 6 This is a partial schematic diagram of the oscillating component and the turbulence component in this application.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1. Main body of the vacuum air conditioning humidifier; 11. Workbench; 12. Vacuum chamber; 13. Barrier curtain; 14. Controller; 2. Transition chamber; 21. Constant temperature atomizing humidifier; 22. Guide pipe; 23. Corrugated hose; 24. Diverter pipe; 25. Nozzle; 26. Infrared heating plate; 27. Electric lifting sealing door; 28. Humidity sensor; 29. ​​Temperature sensor; 3. Mounting housing; 31. Servo motor; 32. First reciprocating screw; 33. First nut seat; 34. First guide roller; 35. First guide groove; 4. Second reciprocating screw; 41. Second nut seat; 42. Mounting plate; 43. Baffle plate; 44. Second guide roller; 45. Second guide groove; 46. Transmission wheel; 47. Transmission belt. Detailed Implementation

[0040] The following is in conjunction with the appendix Figure 1-6 This application will be described in further detail.

[0041] This application discloses a dyeing pre-shrinking method.

[0042] Reference Figure 1 A staining pre-shrinking method, the pre-shrinking method comprising the following steps:

[0043] S1: Based on the material type and characteristics of the textile fabric to be treated, select the corresponding special pre-shrinking process for pre-shrinking treatment before dyeing to fully eliminate residual internal stress and potential shrinkage in the fiber.

[0044] S2: After the pre-shrinking treatment is completed, the textile fabric is dyed within a preset time limit to stabilize the size of the pre-shrinked fabric and maintain the stability of the pre-shrinked size.

[0045] This pre-shrinking method improves dyeing uniformity and reduces color difference. Pre-shrinking before dyeing completely eliminates internal fiber stress, avoiding uneven dyeing and color difference problems caused by uneven shrinkage after dyeing. This reduces the fabric color difference rate to below 0.5%, solving the problem of color difference between the inner and outer layers of the yarn package. It also improves the yield rate. By fully releasing the potential shrinkage of the fibers through pre-shrinking, the fabric shrinkage rate deviation is controlled within ±1%, eliminating the problem of incorrect finished product dimensions. The fabric yield rate is increased by more than 15%, significantly reducing the scrap rate. Simultaneously, it simplifies the process and reduces energy consumption. Through continuous pre-shrinking and dyeing operations, complex processes such as mechanical shrinkage after dyeing and step-by-step wet heat treatment are eliminated, reducing production energy consumption by 30% and avoiding environmental and hand feel problems caused by chemical setting.

[0046] In step S1, when the textile to be processed is a polyester / viscose blended yarn, a vacuum-controlled humidification setting process is used for pre-shrinking treatment.

[0047] The specific process of vacuum humidification setting is as follows: the yarn bobbin is placed inside the vacuum humidification setting equipment. The equipment is first evacuated to a vacuum degree of ≤10Pa, and then 85%RH humidification steam is injected into the chamber. The yarn is then kept at a constant temperature of 40-60℃ for 30 minutes to allow the steam to fully penetrate the yarn.

[0048] In step S1, when the textile fabric to be processed is a knitted elastic fabric or a general fabric, it is processed using an integrated pre-shrinking system for an airflow dyeing machine. The pre-shrinking system includes a humidification unit, a fabric tension regulating roller, and a condensate recovery unit.

[0049] The humidification unit is a steam injection device; the steam injection device is equipped with a tungsten carbide nozzle with a nozzle orifice diameter of 0.5 mm, injects saturated steam at a pressure of 0.2-0.4 MPa, and the steam injection angle is set to 30°.

[0050] The humidification unit is an ultrasonic atomizing humidifier.

[0051] The fabric is conveyed to the steam treatment zone at a constant speed of 20m / min, and the pre-shrinkage rate of the fabric is controlled within the range of 3%-5% by the fabric tension regulating roller.

[0052] The condensate formed after steam condensation is used to wet the gaps between fabric fibers, improve dyeing uniformity, and is recycled by the condensate recovery unit.

[0053] The vacuum air-conditioning and humidifying setting equipment includes a main body 1, a workbench 11 fixed at the upper end of the main body 1, a vacuum chamber 12 fixed at the upper end of the workbench 11, a vacuum system, a humidity control system, and a heating module installed inside the vacuum chamber 12, and barrier curtains 13 fixed at both ends of the vacuum chamber 12. A controller 14 is fixed on the side of the workbench 11, and the controller 14 is electrically connected to the vacuum system, the humidity control system, and the heating module. A transition unit is provided at the end of the vacuum chamber 12.

[0054] The transition unit includes a transition chamber 2 fixed to the upper end of the workbench 11. A constant temperature atomizing humidifier 21 is fixed to the upper end of the transition chamber 2. A guide pipe 22 is fixed to the liquid outlet end of the constant temperature atomizing humidifier 21. The end of the guide pipe 22 away from the constant temperature atomizing humidifier 21 extends into the interior of the transition chamber 2 and is fixed with a corrugated hose 23. A diverter pipe 24 is fixed to the end of the corrugated hose 23 away from the guide pipe 22. Multiple nozzles 25 are fixed on the diverter pipe 24. A swing assembly is provided between the diverter pipe 24 and the transition chamber 2. A turbulence assemblies are provided on the inner wall of the transition chamber 2. An infrared heating plate 26 is fixed on the inner wall of the transition chamber 2. Electric lifting sealing doors 27 are installed at both ends of the transition chamber 2. A humidity sensor 28 and a temperature sensor 29 are fixed on the inner wall of the transition chamber 2. The controller 14 is electrically connected to the constant temperature atomizing humidifier 21, the infrared heating plate 26, the humidity sensor 28, the temperature sensor 29, and the electric lifting sealing door 27.

[0055] The swing assembly includes a mounting housing 3 fixed to the inner wall of the transition chamber 2. A servo motor 31 is fixed to one end of the mounting housing 3. The output end of the servo motor 31 extends into the interior of the mounting housing 3 and is fixed with a first reciprocating lead screw 32. The first reciprocating lead screw 32 is rotatably connected to the mounting housing 3. A first nut seat 33 adapted to the first reciprocating lead screw 32 is sleeved on it. One end of the first nut seat 33 extends out of the mounting housing 3 and is fixedly connected to the diverter pipe 24. A first guide roller 34 is rotatably connected to the end of the diverter pipe 24 away from the first nut seat 33. A first guide groove 35 is opened in the inner wall of the transition chamber 2. The first guide roller 34 extends into the first guide groove 35 and its surface is in contact with the inner wall of the first guide groove 35.

[0056] A second reciprocating screw 4 is fixed inside the mounting housing 3. A second nut seat 41, which is adapted to the second reciprocating screw 4, is fitted onto the second reciprocating screw 4. One end of the first nut seat 33 extends out of the mounting housing 3 and is fixed with a mounting plate 42. Two baffles 43, which are arc-shaped, are fixed on the mounting plate 42. A second guide roller 44 is rotatably connected to the end of the first nut seat 33 away from the mounting plate 42. A second guide groove 45 is opened on the inner wall of the transition chamber 2. The second guide roller 44 extends into the second guide groove 45, and its surface is in contact with the inner wall of the second guide groove 45. A transmission wheel 46 is fixed on both the first reciprocating screw 32 and the second reciprocating screw 4. The two transmission wheels 46 are connected by a transmission belt 47.

[0057] In use, turn on the constant temperature atomizing humidifier 21, infrared heating plate 26, and servo motor 31. The constant temperature atomizing humidifier 21 starts and sprays atomized steam evenly into the transition chamber 2 through the guide pipe 22, corrugated hose 23, diverter pipe 24, and nozzle 25. At the same time, the servo motor 31 drives the first reciprocating screw 32 to rotate, so that the first nut seat 33 is stressed. Under the guidance of the first guide roller 34 and the first guide groove 35, the diverter pipe 24 swings back and forth along the mounting housing 3. The nozzle 25 moves evenly along the axial direction of the transition chamber 2 with the diverter pipe 24, so that the humidifying steam can be evenly diffused to all areas inside the transition chamber 2, avoiding local humidity that is too high or too low. This ensures that the temperature and humidity in all areas of the chamber can change evenly and smoothly, so that all yarns can obtain a consistent transition treatment effect. It also avoids local shrinkage abnormalities caused by uneven temperature gradients, and further ensures the stability of the overall pre-shrinking treatment.

[0058] At the same time, the first reciprocating screw 32 is linked with the second reciprocating screw 4 through the transmission wheel 46 and the transmission belt 47 to rotate. The second nut seat 41 drives the baffle 43 to move back and forth synchronously in the transition chamber 2, agitating the humidifying steam in the transition chamber 2, preventing the steam from accumulating in local areas of the chamber, improving the uniformity of temperature and humidity in the chamber, ensuring the uniformity of the smooth transition of temperature and humidity, and further improving the stability of the yarn after pre-shrinking.

[0059] Infrared heating plate 26 operates continuously, maintaining the temperature inside transition chamber 2 within the range of 30-40℃. Humidity sensor 28 and temperature sensor 29 collect data from inside the chamber in real time and feed it back to controller 14. Controller 14 dynamically adjusts the spray volume of constant temperature atomizing humidifier 21 and the power of infrared heating plate 26 according to preset parameters. Once the humidity inside transition chamber 2 reaches 65%RH and the temperature stabilizes, constant temperature atomizing humidifier 21, servo motor 31, and infrared heating plate 26 stop working. Open the electric lifting sealed door 27 of transition chamber 2 near vacuum chamber 12 and the sealed door of vacuum chamber 12 near the end of transition chamber 2, and send the pre-shrunken yarn bobbin into transition chamber 2. During the transition process, the temperature decreases accordingly. When the temperature drops to room temperature, controller 14 issues a reminder. Then, the operator opens the electric lifting sealed door 27 on the side of transition chamber 2 away from vacuum chamber 12 and removes the transitioned yarn bobbin. Through the transition unit, the pre-shrunken yarn can be gradually transitioned. This design prevents the pre-shrinked yarn from directly contacting the ambient, dry air. It also prevents the yarn from being suddenly exposed to a low-temperature, low-humidity environment after pre-shrinking, which could cause the fibers to shrink or spring back due to a rapid drop in temperature and rapid moisture loss. The transition chamber 2 achieves a smooth transition in temperature and humidity, effectively maintaining the stable state of the fibers after pre-shrinking, thus ensuring that the dimensions and performance of the yarn and fabric remain as expected.

[0060] Working Principle: During the pre-shrinking and dyeing of polyester / viscose blended yarns, the yarns to be treated are made into standard yarn bobbins, and surface dust and impurities are removed. The yarn bobbins are then placed on a rack and sent into the vacuum chamber of a vacuum-conditioned humidification setting equipment. The chamber door is closed and sealed to ensure the chamber's sealing performance meets the requirement of a vacuum degree ≤10Pa. The vacuum system is then activated to evacuate the chamber to a vacuum degree ≤10Pa, completely removing air from the yarn gaps and creating conditions for steam penetration. Next, humidifying steam with 85%RH is injected into the vacuum chamber through the humidity control system, allowing the steam to evenly fill the chamber and penetrate into the yarn. The heating module is then activated to maintain the temperature inside the vacuum chamber at 40–60℃ for 30 minutes, allowing the yarn fibers to fully relax and completely eliminate internal stress and potential shrinkage accumulated in the previous process.

[0061] During the heat preservation process, the constant temperature atomizing humidifier 21, infrared heating plate 26, and servo motor 31 are turned on. The constant temperature atomizing humidifier 21 starts and evenly sprays atomized steam into the transition chamber 2 through the guide pipe 22, corrugated hose 23, diverter pipe 24, and nozzle 25. At the same time, the servo motor 31 drives the first reciprocating screw 32 to rotate, so that the first nut seat 33 is stressed. Under the guidance of the first guide roller 34 and the first guide groove 35, the diverter pipe 24 reciprocates along the mounting housing 3. The nozzle 25 moves evenly along the axial direction of the transition chamber 2 with the diverter pipe 24, so that the humidifying steam can be evenly diffused to all areas inside the transition chamber 2. This avoids local humidity that is too high or too low, and ensures that the temperature and humidity in all areas of the chamber can change evenly and smoothly, so that all yarns can obtain a consistent transition treatment effect. This avoids local shrinkage abnormalities caused by uneven temperature gradients and further ensures the stability of the overall pre-shrinking treatment. At the same time, the first reciprocating screw 32 is linked with the second reciprocating screw 4 through the transmission wheel 46 and the transmission belt 47 to rotate. The second nut seat 41 drives the baffle 43 to move back and forth synchronously in the transition chamber 2, agitating the humidifying steam in the transition chamber 2, preventing the steam from accumulating in local areas of the chamber, improving the uniformity of temperature and humidity in the chamber, ensuring the uniformity of the smooth transition of temperature and humidity, and further improving the stability of the yarn after pre-shrinking.

[0062] Infrared heating plate 26 operates continuously, maintaining the temperature inside transition chamber 2 within the range of 30-40℃. Humidity sensor 28 and temperature sensor 29 collect data from inside the chamber in real time and feed it back to controller 14. Controller 14 dynamically adjusts the spray volume of constant temperature atomizing humidifier 21 and the power of infrared heating plate 26 according to preset parameters. After the humidity inside transition chamber 2 reaches 65%RH and the temperature stabilizes, constant temperature atomizing humidifier 21, servo motor 31, and infrared heating plate 26 stop working. After the heat preservation is completed, the vacuum is broken, and the electric lifting sealing door 27 of transition chamber 2 near vacuum chamber 12 and the sealing door of vacuum chamber 12 near the end of transition chamber 2 are opened. The pre-shrunken yarn bobbin is sent into transition chamber 2. During the transition process, the temperature decreases accordingly. When the temperature drops to room temperature, controller 14 issues a reminder. Afterward, the operator opens the electric lifting sealing door 27 on the side of transition chamber 2 away from vacuum chamber 12 and takes out the transitioned yarn bobbin.

[0063] The pre-shrunken yarn is fed into the dyeing process within 2 hours to maintain the dimensional stability of the pre-shrunken yarn and prevent internal stress rebound. The pre-shrunken yarn is then dyed as usual, and after dyeing, it undergoes dehydration treatment to obtain a finished yarn with stable dimensions and uniform dyeing.

[0064] When pre-shrinking and dyeing knitted elastic fabric / general fabric, the fabric to be treated is flattened, surface wrinkles are removed, and it is connected to the conveyor of the integrated pre-shrinking system of the airflow dyeing machine. The integrated pre-shrinking system, which includes a humidification unit, fabric tension regulating rollers, and a condensate recovery unit, is then activated, and the equipment enters standby mode. Subsequently, a steam jet device or ultrasonic atomizing humidifier can be used to humidify the fabric surface, and the fabric is conveyed to the steam treatment zone at a constant speed of 20 m / min. The fabric tension regulating rollers precisely control the fabric shrinkage rate to 3–5%, ensuring dimensional accuracy. Steam condenses on the fabric surface, forming condensate that penetrates into the interfiber spaces, improving fiber wetting and subsequent dyeing uniformity. The condensate recovery unit simultaneously recovers excess condensate, achieving water resource recycling. After pre-shrinking, the fabric directly enters the airflow dyeing machine for dyeing, with the pre-shrinking to dyeing interval not exceeding 2 hours to maintain stable pre-shrinking results. After dyeing, the fabric is dehydrated to obtain a dimensionally stable, color-consistent finished fabric.

[0065] This pre-shrinking method is used to pre-shrink polyester / viscose blended yarns and knitted elastic / general fabrics, resulting in more uniform dyeing and reduced color difference. Pre-shrinking before dyeing completely eliminates internal fiber stress, avoiding uneven dyeing and color difference problems caused by uneven shrinkage after dyeing. This reduces the fabric color difference rate to below 0.5%, solving the problem of color difference between the inner and outer layers of the yarn package. It also improves the yield rate. By fully releasing the potential shrinkage of the fibers through pre-shrinking, the fabric shrinkage rate deviation is controlled within ±1%, eliminating the problem of incorrect finished product dimensions. The fabric yield rate is increased by more than 15%, significantly reducing the scrap rate. Simultaneously, it simplifies the process and reduces energy consumption. Through continuous pre-shrinking and dyeing operations, complex processes such as mechanical shrinkage after dyeing and step-by-step wet heat treatment are eliminated, reducing production energy consumption by 30% and avoiding environmental and hand feel problems caused by chemical setting.

Claims

1. A staining pre-shrinking method, characterized in that: The pre-shrinking method includes the following steps: S1: Based on the material type and characteristics of the textile fabric to be treated, select the corresponding special pre-shrinking process for pre-shrinking treatment before dyeing to fully eliminate residual internal stress and potential shrinkage in the fiber. S2: After the pre-shrinking treatment is completed, the textile fabric is dyed within a preset time limit to stabilize the size of the pre-shrinked fabric and maintain the stability of the pre-shrinked size.

2. The staining pre-shrinking method according to claim 1, characterized in that: In step S1, when the textile to be processed is a polyester / viscose blended yarn, a vacuum-controlled humidification setting process is used for pre-shrinking treatment.

3. The staining pre-shrinking method according to claim 2, characterized in that: The specific process of vacuum humidification setting is as follows: the yarn bobbin is placed inside the vacuum humidification setting equipment. The equipment is first evacuated to a vacuum degree of ≤10Pa, and then 85%RH humidification steam is injected into the chamber. The yarn is then kept at a constant temperature of 40-60℃ for 30 minutes to allow the steam to fully penetrate the yarn.

4. The staining pre-shrinking method according to claim 1, characterized in that: In step S1, when the textile fabric to be processed is a knitted elastic fabric or a general fabric, it is processed using an integrated pre-shrinking system for an airflow dyeing machine. The pre-shrinking system includes a humidification unit, a fabric tension regulating roller, and a condensate recovery unit.

5. The staining pre-shrinking method according to claim 4, characterized in that: The humidification unit is a steam injection device, which is equipped with a tungsten carbide nozzle with a nozzle orifice diameter of 0.5 mm. It injects saturated steam at a pressure of 0.2-0.4 MPa and the steam injection angle is set to 30°.

6. The staining pre-shrinking method according to claim 4, characterized in that: The humidification unit is an ultrasonic atomizing humidifier.

7. The staining pre-shrinking method according to claim 4, characterized in that: The fabric is conveyed to the steam treatment zone at a constant speed of 20m / min, and the pre-shrinkage rate of the fabric is controlled within the range of 3%-5% by the fabric tension regulating roller.

8. The staining pre-shrinking method according to claim 4, characterized in that: The condensate formed after steam condensation is used to wet the gaps between fabric fibers, improve dyeing uniformity, and is recycled by the condensate recovery unit.

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