Dyeing method of meta-aramid yarn

Abstract

The invention belongs to the technical field of textile printing and dyeing, and particularly relates to a dyeing method of meta-aramid yarn. The dyeing method of the meta-aramid yarn comprises the following steps: dissolving an S-type or SE-type disperse dye and a dispersing agent in water to prepare a dye solution; in the meta-aramid yarn winding process, a single yarn is completely immersed in the dye liquor for contact, saturated adsorption is performed, and the meta-aramid yarn is wound into a loose cone yarn; carrying out high-temperature steaming fixation; the color-fixed cone yarn is put into a cone yarn dyeing machine to be subjected to reduction cleaning and normal-temperature water washing, the water-washed cone yarn is dehydrated and dried, dyed meta-aramid yarn is obtained, the dark color variety is subjected to redyeing through the dried yarn, and then the dyed meta-aramid yarn is obtained through steaming color fixing and aftertreatment. A disperse dye adopted for redyeing is an E-type disperse dye. The dyeing method of the meta-aramid yarn provided by the invention is low in cost, simple to operate, environment-friendly and high in production efficiency under the condition of normal temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of textile printing and dyeing, and particularly relates to a dyeing method for meta-aramid yarn. Background Art

[0002] Meta-aramid fiber (aramid 1313) is polyisophthalamide (m-phenylene isophthalamide) fiber, which is a kind of aromatic polyamide fiber. Meta-aramid has excellent physical and mechanical properties. Its strength is 5 to 6 times that of steel wire, its modulus is 2 to 3 times that of steel wire, and its weight is only about 1 / 5 of that of steel wire. Its limiting oxygen index is 28% to 32%. It is a permanent flame retardant fiber. It does not burn or drip when it encounters fire. When the temperature is higher than 400°C, the fiber will decompose and carbonize, forming a unique thermal insulation barrier. In addition, meta-aramid has good stability in acids, alkalis, bleaching agents, reducing agents, and organic solvents, and also has excellent radiation resistance and electrical insulation. Based on the above characteristics, meta-aramid is often used to make protective equipment such as aerospace suits, fire suits, heat-resistant gloves, fire curtains, antistatic work clothes, and protective clothing for corrosive places. However, due to the strong inter-chain interaction, high crystallinity and high glass transition temperature of meta-aramid polymer, it is difficult for dye molecules to enter the interior of the fiber, resulting in difficulty in dyeing, which greatly limits its application in the clothing field.

[0003] Through the research on the manufacturing process and structural characteristics of meta-aramid fiber, the main dyeing methods of meta-aramid fiber at present include ultra-high temperature dyeing, carrier dyeing, solvent dyeing, supercritical CO2 dyeing, ionic liquid dyeing, stock solution dyeing, plasma pretreatment dyeing, surface treatment dyeing, etc. The supercritical CO2 dyeing method requires the meta-aramid fiber to be dyed under heating and pressurized conditions. This method can improve the dyeing depth and dye penetration of meta-aramid fiber and obtain good color fastness, but the dyeing temperature is high and the pressurized pressure is large. After dyeing, the disperse dye and carbon dioxide need to be recovered, which increases the production process.

[0004] In the prior art, meta-aramid is dyed under normal pressure. Although this method avoids the fiber strength problem caused by high pressure, the yarn needs to be roughened before dyeing, which destroys the fiber surface to a certain extent and still damages the strength of the yarn.

[0005] Patent publication CN118326688A proposes a meta-aramid carrier dyeing process, including modification of meta-aramid fabric and dyeing of the modified meta-aramid fabric. This method enables meta-aramid to have good color fastness, but the carrier method still has some problems at this stage, such as the irritating odor and toxicity of the carrier used, and the residual carrier on the fabric is difficult to remove. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a dyeing method for meta-aramid yarn, which has low cost, room temperature conditions, simple operation, environmental protection and high production efficiency.

[0007] The dyeing method of the meta-aramid yarn of the present invention comprises the following steps: (1) Yarn dyeing: dissolving S-type or SE-type disperse dye and dispersant in water to prepare dye liquor; using a high-speed single yarn dyeing machine (GA398 model) to completely immerse a single yarn in the dye liquor during the winding process of meta-aramid yarn, saturate it with dye liquor, and wind it into loose cone yarn; (2) Steaming color fixation: The loose yarn is steamed at high temperature with saturated steam to fix the color; (3) Post-treatment: The color-fixed bobbin yarn is placed in a bobbin dyeing machine for reduction cleaning and washing at room temperature. The washed bobbin yarn is dehydrated and dried to obtain dyed meta-aramid yarn.

[0008] The invention also includes the following steps: (4) re-dyeing the yarn: when the color of the yarn still needs to be deepened after dyeing, the meta-aramid yarn obtained in step (3) is re-dyeing with a dyeing solution made of an E-type disperse dye and a dispersant, so that the single yarn is completely immersed in the dyeing solution, saturated with the dyeing solution, and wound into a loose bobbin yarn; (5) Steaming and color fixing: The loose yarn in step (4) is subjected to high-temperature steaming and color fixing using saturated steam; (6) Post-treatment: The color-fixed bobbin yarn in step (5) is placed in a bobbin yarn dyeing machine for reduction cleaning and washing at room temperature. The washed bobbin yarn is dehydrated and dried to obtain the final dyed meta-aramid yarn.

[0009] In the dye liquor of step (1), the concentration of S-type or SE-type disperse dye is 2-50 g / L, and the concentration of dispersant is 1-2 g / L.

[0010] In step (1), the liquid carrying rate of the meta-aramid yarn on the loose yarn is 30% to 50%, and the water density of the loose yarn is 0.40 to 0.55 g / cm 3 .

[0011] The high temperature steaming temperature of step (2) is 130-140° C. and the time is 30-50 min.

[0012] The reduction cleaning in step (3) uses NaOH and hydrosulfite, with the amount of NaOH being 1-2 g / L and the amount of hydrosulfite being 2-4 g / L.

[0013] The reduction cleaning in step (3) is carried out at a temperature of 80 to 90° C. and for a time of 15 to 20 minutes.

[0014] The time of washing with water at room temperature in step (3) is 5 to 10 minutes; and the drying is carried out by radio frequency drying, and the drying time is 2 to 3 hours.

[0015] In the dyeing solution of step (4), the concentration of E-type disperse dye is 5-20 g / L, the concentration of dispersant is 1-1.5 g / L, and the dyeing solution is also prepared using water as solvent.

[0016] In step (4), the liquid carrying rate of the re-dyed meta-aramid yarn on the loose yarn is 30% to 50%, and the water density of the loose yarn is 0.40 to 0.55 g / cm 3 .

[0017] Specifically, the meta-aramid yarn dyeing method comprises the following steps: (1) Yarn dyeing: Dissolve SE type disperse dye or S type disperse dye and dispersant in water, mix well, and prepare dye solution (SE type disperse dye or S type disperse dye 2-50 g / L, dispersant 1-2 g / L); use a high-speed single yarn dyeing machine (GA398 model) to make a single yarn fully contact with the dye solution during the winding process of meta-aramid yarn, so that the meta-aramid yarn is saturated with the dye solution and wound into loose cone yarn; the liquid carrying rate of the meta-aramid yarn on the loose cone yarn is 30%-50%, and the water density of the loose cone yarn is 0.40-0.55 g / cm 3 ; (2) Steaming and color fixing: Put the loose yarn into the steamer and use saturated steam to fix the color at high temperature. The temperature is 130-140℃ and the time is 30-50min. (3) Post-treatment: The color-fixed bobbin yarn is placed in a bobbin dyeing machine. After entering water, 1-2 g / L of NaOH solution and 2-4 g / L of hydrosulfite are added to perform reduction cleaning at 80-90°C for 15-20 min, then the yarn is drained. The bobbin yarn is re-entered into water for 5-10 min of normal temperature washing, then the yarn is drained. The washed bobbin yarn is dehydrated and radio frequency dried for 2-3 h to obtain dyed meta-aramid yarn.

[0018] The method further comprises the following steps: (4) re-dyeing the yarn: re-dyeing the yarn obtained in step (3) with an E-type disperse dye; dissolving the E-type disperse dye and a dispersant in water to prepare a dye solution (5 to 20 g / L of the E-type disperse dye and 1 to 1.5 g / L of the dispersant); completely immersing a single yarn in the dye solution for saturated adsorption, and winding the yarn into a loose bobbin; (5) Steaming and color fixing: The loose yarn in step (4) is subjected to high-temperature steaming and color fixing using saturated steam; (6) Post-treatment: The color-fixed bobbin yarn in step (5) is placed in a bobbin yarn dyeing machine for reduction cleaning and washing at room temperature. The washed bobbin yarn is dehydrated and dried to obtain the final dyed meta-aramid yarn.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The meta-aramid yarn dyeing method of the present invention does not require yarn pretreatment, and does not use a carrier or other solvents during the dyeing process to achieve room-temperature dyeing of the aramid yarn. The production process is short and does not cause additional burden on the environment. (2) The dyeing method of the meta-aramid yarn of the present invention is carried out at room temperature, has low requirements on production equipment, simple production operation, high production efficiency and low production cost; (3) In the dyeing method of the meta-aramid yarn of the present invention, small molecule E-type disperse dyes are used in the re-dyeing, and secondary high-temperature steaming can further enhance the fixation of the dye to the fiber, thereby improving the dyeing depth and fastness. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with specific embodiments.

[0021] The raw materials and additives used in the following examples and comparative examples were all purchased from the market.

[0022] SE type disperse dye Sumikaron Blue SE-RPD (B) was purchased from Sumitomo Chemical (Shanghai) Co., Ltd.; S-type disperse dye Foron Navy S-WF was purchased from Archroma Chemicals (China) Co., Ltd.; E-type disperse dye Sumikaron Blue E-RPD (EA) was purchased from Sumitomo Chemical (Shanghai) Co., Ltd.; S-type disperse dye Foron Rubine S-WF was purchased from Archroma Chemicals (China) Co., Ltd.; E-type disperse dye Sumikaron Red E-RPD (EA) was purchased from Sumitomo Chemical (Shanghai) Co., Ltd.; S-type disperse dye Sumikaron Blue S-3RF (A) was purchased from Sumitomo Chemical (Shanghai) Co., Ltd.; Dispersant YS-28 was purchased from Yantai Yuanming Textile Technology Co., Ltd.; Dispersant RDT-35 was purchased from Shanghai Xintian Economic and Trade Co., Ltd.; The GA398 high-speed single yarn dyeing machine was purchased from Jiangyin Tongyuan Textile Machinery Co., Ltd.

[0023] Example 1 The dyeing method of meta-aramid yarn comprises the following steps: (1) Yarn dyeing: SE type disperse dye Sumikaron Blue SE-RPD(B) and dispersant YS-28 were dissolved in water and mixed evenly to prepare dye solution (SE type disperse dye Sumikaron Blue SE-RPD(B) 2 g / L, dispersant YS-28 1 g / L); a high-speed single yarn dyeing machine (GA398) was used to fully contact the dye solution during the winding process of the meta-aramid yarn, so that the meta-aramid yarn was saturated with the dye solution and wound into a loose cone yarn; the liquid carrying rate of the meta-aramid yarn on the loose cone yarn was 30%, and the water content density of the loose cone yarn was 0.55 g / cm 3 ; (2) Steaming fixation: Put the loose yarn into the steamer and use saturated steam to fix the color at high temperature. The temperature is 130℃ and the time is 30 minutes. (3) Post-treatment: The color-fixed bobbin yarn is placed in a bobbin dyeing machine. After entering water, 1 g / L concentrated NaOH solution and 2 g / L hydrosulfite are added to perform reduction cleaning at 80°C for 15 min, then the yarn is drained. The bobbin yarn is re-entered into water for 5 min at room temperature, then the yarn is drained. The washed bobbin yarn is dehydrated and radio-frequency dried for 2.5 h to obtain dyed meta-aramid yarn.

[0024] Example 2 The dyeing method of meta-aramid yarn comprises the following steps: (1) Yarn dyeing: S-type disperse dye Foron Navy S-WF and dispersant YS-28 were dissolved in water and mixed evenly to prepare dye solution (S-type disperse dye Foron Navy S-WF 20g / L, dispersant YS-28 1g / L). A high-speed single yarn dyeing machine (GA398) was used to fully contact the single yarn with the dye solution during the winding process of the meta-aramid yarn. The meta-aramid yarn was saturated with the dye solution and wound into a loose cone yarn. The liquid content of the meta-aramid yarn on the loose cone yarn was 40%, and the water content density of the loose cone yarn was 0.45g / cm 3 ; (2) Steaming fixation: Put the loose yarn into the steamer and use saturated steam to fix the color at high temperature. The temperature is 135℃ and the time is 35min. (3) Post-treatment: The color-fixed bobbin yarn is placed in a bobbin dyeing machine. After entering water, 1 g / L NaOH solution and 3 g / L hydrosulfite are added to perform reduction cleaning at 80°C for 15 min, then the yarn is drained. The bobbin yarn is re-entered into water for 10 min at room temperature, then the yarn is drained. The washed bobbin yarn is dehydrated and radio-frequency dried for 2.5 h to obtain dyed meta-aramid yarn.

[0025] Example 3 The dyeing method of meta-aramid yarn comprises the following steps: (1) Yarn dyeing: SE type disperse dye Sumikaron Blue SE-RPD (B) and dispersant RDT-35 were dissolved in water and mixed evenly to prepare dye solution (SE type disperse dye Sumikaron Blue SE-RPD (B) 50 g / L, dispersant RDT-35 2 g / L); a high-speed single yarn dyeing machine (GA398) was used to fully contact the dye solution during the winding process of the meta-aramid yarn, so that the meta-aramid yarn was saturated with the dye solution and wound into a loose cone yarn; the liquid content of the meta-aramid yarn on the loose cone yarn was 50%, and the water content density of the loose cone yarn was 0.40 g / cm 3 ; (2) Steaming fixation: Put the loose bobbin yarn into the steamer and use saturated steam for high-temperature steam fixation at 140°C for 50 minutes; (3) Post-treatment: Put the color-fixed bobbin yarn into the bobbin yarn dyeing machine, add 2g / L NaOH solution and 4g / L hydrosulfite into water, perform reduction cleaning at 90℃ for 20min, drain the water, re-enter water for 10min at room temperature, drain the water, dehydrate the washed bobbin yarn and perform radio frequency drying for 3h; (4) Yarn re-dyeing: The color of the yarn obtained in step (3) is further deepened and re-dyeing is performed using an E-type disperse dye; the E-type disperse dye Sumikaron Blue E-RPD (EA) and the dispersant RDT-35 are dissolved in water and mixed evenly to prepare a dye solution (E-type disperse dye Sumikaron Blue E-RPD (EA) 20 g / L, dispersant RDT-35 1.5 g / L); a high-speed single yarn dyeing machine is used to fully contact a single yarn with the dye solution during the winding process of the meta-aramid yarn, and the yarn is wound into a loose cone yarn; the liquid carrying rate of the meta-aramid yarn on the loose cone yarn is 50%, and the water content density of the loose cone yarn is 0.50 g / cm 3 ; (5) Steaming and color fixing: the loose bobbin yarn of step (4) is placed in a steamer and steamed and fixed with saturated steam at a temperature of 140°C for 50 minutes; (6) Post-treatment: The yarn after color fixation in step (5) is placed in a yarn dyeing machine. After entering water, 2 g / L NaOH solution and 4 g / L hydrosulfite are added to perform reduction cleaning at 90°C for 20 min, then the yarn is drained. The yarn is re-entered into water for 10 min at room temperature, then the yarn is drained. The washed yarn is dehydrated and radio-frequency dried for 3 h to obtain dark-dyed meta-aramid yarn.

[0026] Example 4 The dyeing method of meta-aramid yarn comprises the following steps: (1) Yarn dyeing: SE type disperse dye Foron Rubine S-WF and dispersant RDT-35 were dissolved in water and mixed evenly to prepare dye solution (SE type disperse dye Foron Rubine S-WF 50g / L, dispersant RDT-35 2g / L); a high-speed single yarn dyeing machine (GA398 model) was used to fully contact the single yarn with the dye solution during the winding process of the meta-aramid yarn, and the meta-aramid yarn was saturated with the dye solution and wound into a loose cone yarn; the liquid carrying rate of the meta-aramid yarn on the loose cone yarn was 50%, and the water content density of the loose cone yarn was 0.50g / cm 3 ; (2) Steaming fixation: Put the loose bobbin yarn into the steamer and use saturated steam for high-temperature steam fixation at a temperature of 135°C for 45 minutes; (3) Post-treatment: Put the color-fixed bobbin yarn into the bobbin yarn dyeing machine, add 2g / L NaOH solution and 3g / L hydrosulfite into water, perform reduction cleaning at 85°C for 20min, drain the water, re-enter the water for 10min at room temperature, drain the water, dehydrate the washed bobbin yarn and perform radio frequency drying for 3h; (4) Yarn re-dyeing: The color of the yarn obtained in step (3) is further deepened by re-dyeing with an E-type disperse dye; the E-type disperse dye Sumikaron Red E-RPD (EA) and the dispersant RDT-35 are dissolved in water and mixed evenly to prepare a dye solution (E-type disperse dye Sumikaron Red E-RPD (EA) 5 g / L, dispersant RDT-35 1 g / L); a high-speed single yarn dyeing machine is used to fully contact the single yarn with the dye solution during the winding process of the meta-aramid yarn, saturate the dye solution, and wind it into a loose cone yarn; the liquid carrying rate of the meta-aramid yarn on the loose cone yarn is 30%, and the water content density of the loose cone yarn is 0.45 g / cm 3 ; (5) Steaming and color fixing: the loose bobbin yarn of step (4) is placed in a steamer and steamed and fixed with saturated steam at a temperature of 135°C for 45 minutes; (6) Post-treatment: The yarn after color fixation in step (5) is placed in a yarn dyeing machine. After entering water, 2 g / L NaOH solution and 3 g / L hydrosulfite are added to perform reduction cleaning at 80°C for 15 min, then the yarn is drained. The yarn is re-entered into water for 10 min at room temperature, then the yarn is drained. The washed yarn is dehydrated and radio frequency dried for 3 h to obtain dark-dyed meta-aramid yarn.

[0027] Comparative Example 1 A method for dyeing meta-aramid yarn comprises the following steps: (1) Yarn dyeing: SE type disperse dye Sumikaron Blue SE-RPD(B) and dispersant YS-28 were dissolved in water and mixed evenly to prepare dye solution (SE type disperse dye Sumikaron Blue SE-RPD(B) 2 g / L, dispersant YS-28 1 g / L); a high-speed single yarn dyeing machine (GA398) was used to fully contact the dye solution during the winding process of meta-aramid yarn, saturate the dye solution, and wind it into loose cone yarn; the liquid content of the meta-aramid yarn on the loose cone yarn was 30%, and the water content density of the loose cone yarn was 0.55 g / cm 3 ; (2) Steaming fixation: Put the loose bobbin yarn into the steamer and use saturated steam for high-temperature steam fixation at 120°C for 30 minutes; (3) Post-treatment: The color-fixed bobbin yarn is placed in a bobbin yarn dyeing machine. After entering water, 1 g / L NaOH solution and 1 g / L hydrosulfite are added to perform reduction cleaning at 80°C for 15 min, then the yarn is drained. The bobbin yarn is re-entered into water for 5 min at room temperature, then the yarn is drained. The washed bobbin yarn is dehydrated and radio-frequency dried for 2.5 h to obtain dyed meta-aramid yarn.

[0028] Comparative Example 2 A method for dyeing meta-aramid yarn comprises the following steps: (1) Yarn dyeing: Dissolve S-type disperse dye Foron Navy S-WF and dispersant YS-28 in water and mix them evenly to prepare dye solution (S-type disperse dye Foron Navy S-WF 20g / L, dispersant YS-28 1g / L). Use a high-speed single yarn dyeing machine (GA398) to fully contact the dye solution during the winding process of meta-aramid yarn, saturate the dye solution, and wind it into loose cone yarn. The liquid content of the meta-aramid yarn on the loose cone yarn is 40%, and the water content density of the loose cone yarn is 0.45g / cm 3 ; (2) Steaming fixation: Put the loose yarn into the steamer and use saturated steam to fix the color at high temperature. The temperature is 135℃ and the time is 20min. (3) Post-treatment: The color-fixed bobbin yarn is placed in a bobbin dyeing machine. After entering water, 1 g / L NaOH solution and 3 g / L hydrosulfite are added to perform reduction cleaning at 80°C for 15 min, then the yarn is drained. The bobbin yarn is re-entered into water for 10 min at room temperature, then the yarn is drained. The washed bobbin yarn is dehydrated and radio-frequency dried for 2.5 h to obtain dyed meta-aramid yarn.

[0029] Comparative Example 3 A method for dyeing meta-aramid yarn comprises the following steps: (1) Yarn dyeing: SE type disperse dye Sumikaron Blue SE-RPD (B) and dispersant RDT-35 were dissolved in water and mixed evenly to prepare dye solution (SE type disperse dye Sumikaron Blue SE-RPD (B) 50 g / L, dispersant RDT-35 2 g / L); a high-speed single yarn dyeing machine (GA398) was used to fully contact the dye solution during the winding process of meta-aramid yarn, saturate the dye solution, and wind it into loose cone yarn; the liquid carrying rate of meta-aramid yarn on the loose cone yarn was 50%, and the water content density of the loose cone yarn was 0.40 g / cm 3 ; (2) Steaming fixation: Put the loose bobbin yarn into the steamer and use saturated steam for high-temperature steam fixation at 140°C for 50 minutes; (3) Post-treatment: Put the color-fixed bobbin yarn into the bobbin yarn dyeing machine, add 2g / L NaOH solution and 4g / L hydrosulfite into water, perform reduction cleaning at 90℃ for 20min, drain the water, re-enter water for 10min at room temperature, drain the water, dehydrate the washed bobbin yarn and perform radio frequency drying for 3h; (4) Yarn re-dyeing: The color of the yarn obtained in step (3) is further deepened and re-dyeing is performed using an S-type disperse dye; the S-type disperse dye Sumikaron Blue S-3RF (A) and the dispersant RDT-35 are dissolved in water and mixed evenly to prepare a dye solution (S-type disperse dye Sumikaron Blue S-3RF (A) 20 g / L, dispersant RDT-35 1.5 g / L); a high-speed single yarn dyeing machine is used to fully contact a single yarn with the dye solution during the winding process of the meta-aramid yarn, saturate the yarn with the dye solution, and wind the yarn into a loose cone; the liquid carrying rate of the meta-aramid yarn on the loose cone is 50%, and the water content density of the loose cone is 0.50 g / cm 3 ; (5) Steaming and color fixing: the loose bobbin yarn of step (4) is placed in a steamer and steamed and fixed with saturated steam at a temperature of 140°C for 50 minutes; (6) Post-treatment: The yarn after color fixation in step (5) is placed in a yarn dyeing machine. After entering water, 2 g / L NaOH solution and 4 g / L hydrosulfite are added to perform reduction cleaning at 90°C for 20 min, then the yarn is drained. The yarn is re-entered into water for 10 min at room temperature, then the yarn is drained. The washed yarn is dehydrated and radio-frequency dried for 3 h to obtain dark-dyed meta-aramid yarn.

[0030] The meta-aramid yarns dyed in the above examples and comparative examples were tested according to the following standards: the color fastness to rubbing test standard is GB / T 3920-2008 "Textiles - Tests for Color Fastness - Color Fastness to Rubbing", and the color fastness to washing test standard is GB / T 3921-2008 "Textiles - Tests for Color Fastness - Color Fastness to Washing". The K / S value of the dyed yarn was measured using a Datacolor 600 computer colorimeter. The test results are shown in Table 1.

[0031] Table 1 Test results

[0032] It can be seen from the test results in Table 1 that in Comparative Example 1, lowering the steaming temperature affects the color fixing effect of the meta-aramid yarn, and the dry and wet friction color fastness, soap color fastness, and dyeing depth of the meta-aramid dyed yarn are not as good as those in Example 1; in Comparative Example 2, the steaming time is reduced, and the dry and wet friction color fastness, soap color fastness, and dyeing depth of the meta-aramid dyed yarn are not as good as those in Example 2; in Comparative Example 3, the yarn is re-dyed with S-type disperse dyes, and the dry and wet friction color fastness and soap color fastness of the re-dyed meta-aramid yarn are not as good as those in Example 3.

Claims

1. A method for dyeing meta-aramid yarn, characterized in that: The following steps are involved: (1) Yarn dyeing: S-type or SE-type disperse dye and dispersant are dissolved in water to prepare dye solution; during the winding process of meta-aramid yarn, a single yarn is completely immersed in the dye solution, saturated with adsorption, and wound into loose cone yarn; (2) Steaming color fixation: The loose yarn is steamed at high temperature with saturated steam to fix the color; (3) Post-treatment: The color-fixed bobbin yarn is placed in a bobbin dyeing machine for reduction cleaning and washing at room temperature. The washed bobbin yarn is dehydrated and dried to obtain dyed meta-aramid yarn.

2. The method for dyeing meta-aramid yarn according to claim 1, characterized in that: The following steps are also included: (4) Yarn re-dyeing: the dyed meta-aramid yarn obtained in step (3) is re-dyed with a dye solution made of an E-type disperse dye and a dispersant to form a loose cone yarn; (5) Steaming and color fixing: The loose yarn in step (4) is subjected to high-temperature steaming and color fixing using saturated steam; (6) Post-treatment: The color-fixed bobbin yarn in step (5) is placed in a bobbin yarn dyeing machine for reduction cleaning and washing at room temperature. The washed bobbin yarn is dehydrated and dried to obtain the final dyed meta-aramid yarn.

3. The method for dyeing meta-aramid yarn according to claim 1, characterized in that: In the dye liquor of step (1), the concentration of S-type or SE-type disperse dye is 2-50 g / L, and the concentration of dispersant is 1-2 g / L.

4. The method for dyeing meta-aramid yarn according to claim 1, characterized in that: In step (1), the liquid carrying rate of the meta-aramid yarn on the loose yarn is 30% to 50%, and the water density of the loose yarn is 0.40 to 0.55 g / cm 3 .

5. The method for dyeing meta-aramid yarn according to claim 1, characterized in that: The high temperature steaming temperature of step (2) is 130-140° C. and the time is 30-50 min.

6. The method for dyeing meta-aramid yarn according to claim 1, characterized in that: The reduction cleaning in step (3) uses NaOH and hydrosulfite, with the amount of NaOH being 1-2 g / L and the amount of hydrosulfite being 2-4 g / L.

7. The method for dyeing meta-aramid yarn according to claim 1, characterized in that: The reduction cleaning in step (3) is carried out at a temperature of 80 to 90° C. and for a time of 15 to 20 minutes.

8. The method for dyeing meta-aramid yarn according to claim 1, characterized in that: The time of washing with water at room temperature in step (3) is 5 to 10 minutes; and the drying is carried out by radio frequency drying, and the drying time is 2 to 3 hours.

9. The method for dyeing meta-aramid yarn according to claim 2, characterized in that: In the dye solution of step (4), the concentration of the E-type disperse dye is 5-20 g / L, and the concentration of the dispersant is 1-1.5 g / L.

10. The method for dyeing meta-aramid yarn according to claim 2, characterized in that: In step (4), the liquid carrying rate of the re-dyed meta-aramid yarn on the loose yarn is 30% to 50%, and the water density of the loose yarn is 0.40 to 0.55 g / cm 3 .

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