Dyeing process based on polyester yarns after enzyme recovery

Abstract

The invention belongs to the technical field of textile dyeing, and particularly relates to a dyeing process of polyester yarn after enzyme recovery, which sequentially comprises the following steps: preparing, loosening yarn, feeding into a vat, pre-treating to remove oil, washing for the first time, dyeing, draining at high temperature, post-treating to reduce and clean, oiling, washing for the second time, dehydrating and drying, the washed yarn is dyed in a dye vat according to disperse dye, 0.2-1 g / l glacial acetic acid and 1-3 g / l strong dispersing and leveling agent, the owf content of the disperse dye in the dye vat is 0.3-4%, and the bath ratio is 1: (5-10). The one-bath degreaser is used for performing fine pretreatment on the cone yarn, then the dye and various auxiliaries are added, temperature and time are controlled, the dyeing effect is enhanced, the color fastness is remarkably improved, more importantly, the anti-yellowing capacity of the yarn is effectively enhanced by introducing the anti-phenolic yellowing agent, and the dyed polyester yarn has the advantages that the anti-yellowing performance of the yarn is improved, so that the anti-yellowing performance of the polyester yarn is improved, and the anti-yellowing performance of the polyester yarn is improved. And the physical and chemical properties meet the strict requirements and use standards of textiles on yarns.

Description

Technical Field

[0001] The invention belongs to the technical field of textile dyeing, and particularly relates to a dyeing process for polyester yarn based on enzyme recovery. Background Art

[0002] In recent years, with the rapid increase in the production and sales of polyester, the problem of waste polyester treatment has become increasingly prominent. The difficulty and cost of waste polyester treatment have become a major challenge to the development of the industry. Although traditional physical and chemical recycling methods can achieve the reuse of waste polyester to a certain extent, they have many limitations, such as the need for high temperature and high pressure environment, serious equipment corrosion, and low recovery rate. These problems not only increase the recycling cost, but also limit the sustainable use of waste polyester. In this context, the technology of recycling polyester with bio-enzyme came into being, providing a new idea for the recycling of waste polyester. This technology uses the catalytic effect of bio-enzyme at room temperature and pressure to degrade waste bottles, plastics, clothing and other PET-containing products into PTA and MEG monomers, which are then condensed and polymerized to form PET particles, which are finally spun into yarn. This method not only has a high recovery rate (up to 96%), but is also environmentally friendly, has low equipment requirements and a long equipment life. It is an effective way to achieve sustainable development of polyester. However, although enzyme-recycled polyester yarn has significant advantages in environmental protection and economy, the existing dyeing process fails to fully meet its dyeing needs. Since the surface properties and internal structure of enzyme-recycled polyester yarn may change during the biological enzyme treatment process, its dyeing characteristics are significantly different from those of traditional polyester yarn. Therefore, when traditional dyeing processes are applied to enzyme-recycled polyester yarn, they often face problems such as insufficient color fastness, reduced anti-yellowing ability, environmental challenges, and insufficient adaptability. The color fastness problem is mainly reflected in the decrease in the ability of dyes to combine with yarns, which causes the dyed yarns to fade easily and cannot meet the strict requirements of textiles for color fastness. The reduction in anti-yellowing ability is because certain components or structural changes in the yarn make it more susceptible to external factors, causing the yarn to turn yellow during use. In addition, environmental challenges and lack of adaptability are also urgent issues to be addressed. During the dyeing process, if a large amount of chemical reagents continue to be used, wastewater discharge and environmental pollution will increase; and enzyme-recycled polyester yarns of different types and specifications have different surface properties and internal structures. Traditional dyeing processes may not be able to fully adapt to these differences, resulting in unstable or inconsistent dyeing effects. Summary of the invention

[0003] 1. Technical issues to be resolved In order to solve the problems existing in the traditional dyeing process in the dyeing process of enzyme-recovered polyester yarn, the present invention provides a dyeing process based on enzyme-recovered polyester yarn, which ensures that the dyed yarn has good color fastness, yellowing resistance, environmental protection and adaptability.

[0004] (II) Technical solution The present invention is implemented by the following technical scheme: The present invention proposes a dyeing process for polyester yarn after enzyme recovery, comprising the following steps in order: preparation, yarn loosening, cylinder feeding, pre-treatment degreasing, first water washing, dyeing, high-temperature drainage, post-treatment reduction cleaning, oiling, second water washing, dehydration and drying: in, In the pre-treatment degreasing process, the yarn after entering the cylinder is heated to 80-90°C at room temperature and maintained for 15-25 minutes, and treated with 25-35g of the same-bath degreasing agent at a bath ratio of 1:5-10; In the dyeing process, the yarn after washing is dyed in a dyeing vat according to disperse dyes, 0.2-1g / l glacial acetic acid and 1-3g / l strong dispersing leveling agent. The disperse dye owf (the percentage of owf dye relative to the weight of the fabric) content in the dyeing vat is 0.3-4%, and the bath ratio is 1:5-10. During the dyeing process, the temperature in the dyeing vat is heated from room temperature to 75-85°C and maintained for 5-15 minutes, then heated to 105-115°C at a rate of 0.5-1°C / min and maintained for 5-15 minutes, and then heated to 125-135°C at a rate of 0.5-2°C / min and maintained for 15-25 minutes to complete the dyeing; In the oiling process, the yarn after reduction cleaning is immersed in water, the temperature is controlled at 30-50°C, the speed of the oiling machine is adjusted to fix the oil on the yarn, and then naturally cooled; the oil is composed of 1-2 parts by mass of a hydrophilic softener, 1-2 parts by mass of silicone oil, 1-2 parts by mass of a strong antistatic agent and 1-2 parts by mass of an anti-phenol yellowing agent; The specific steps are as follows: a) Preparation: Prepare the enzyme-recovered polyester yarn to be dyed; b) Yarn loosening: placing the polyester yarn on a cone loosening machine for yarn loosening; c) Entering the dyeing vat: Put the loosened polyester yarn into the yarn loading frame of the dyeing vat to form a bobbin yarn; d) Pre-treatment degreasing: the bobbin yarn is treated in the above-mentioned pre-treatment degreasing process to obtain degreasing polyester yarn; e) First washing: The deoiled polyester yarn is thoroughly rinsed with clean water to remove the residual deoiling agent and emulsified oil stains in the same bath, thereby obtaining the polyester yarn after the first washing; f) dyeing: dyeing the polyester yarn after the first washing by the steps of the above dyeing process; g) High-temperature drainage: After dyeing is completed, drain the water in the dyeing tank and fish out the dyed polyester yarn; h) Post-treatment reduction cleaning: immerse the dyed polyester yarn in water, add a reducing agent, heat it to 80-90°C and keep it for 10-20 minutes, then rinse it with a large amount of clean water until the water is clear, to obtain a reduction-cleaned polyester yarn; the reducing agent is composed of 1-3g / l sodium hypochlorite, 1-3g / l caustic soda and 0.5-2g / l glacial acetic acid; i) Oiling: The yarn after post-treatment reduction cleaning is oiled using the steps in the above oiling process, and then naturally cooled; j) Second washing: After cooling, rinse the polyester yarn thoroughly with clean water to remove excess oil and floating matter; k) Dehydration: The polyester yarn after the second washing is placed in a centrifugal dehydrator for dehydration; l) Drying: The dehydrated polyester yarn is evenly heated and dried in an oven to finally obtain the desired polyester yarn.

[0005] Preferably, in the step a), the polyester yarn further comprises a petroleum-based polyester yarn or a chemically recycled polyester yarn.

[0006] The strong dispersing leveling agent is one of the leveling agent EDER or the Peregrine O dye series or the RDP-2000 dye or the WYR-1 dye or the β-cyclodextrin dye.

[0007] (III) Beneficial effects Compared with the prior art, the present invention has the following beneficial effects: In the present invention, the same-bath deoiling agent is used to perform fine pretreatment on the bobbin yarn, and then dyes and various auxiliaries are added as well as the temperature and time are controlled to enhance the dyeing effect and significantly improve the color fastness. More importantly, by introducing an anti-phenol yellowing agent, the anti-yellowing ability of the yarn is effectively enhanced, and the physical and chemical properties of the dyed polyester yarn meet the strict requirements and usage standards of textiles for yarn. DETAILED DESCRIPTION

[0008] In this technical solution: In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0009] Example 1: Preparation of light pink polyester yarn; Preparation: Select enzyme-recovered polyester yarn, the yarn specification is 150D / 36F DTY; Loose cone: Place the polyester yarn that has been wound on the loose cone machine, unwind the yarn from the original cone yarn, and loosely wind it on another cone through the loose cone machine. During this process, a certain tension will be applied to the yarn, but it is generally relaxed, forming a loose cone yarn with consistent density and good formation; Entering the dyeing vat: The loosened yarn is taken from the loosening machine and carefully placed on the yarn loading rack of the dyeing vat to ensure that the yarn can move evenly and absorb the dye in the dyeing vat; Pre-treatment degreasing: Pre-treatment degreasing is to pre-treat the bobbin yarn with 30g of degreasing agent in the same bath at a bath ratio of 1:8, and then the temperature is raised to 90°C at room temperature and maintained for 20 minutes to obtain degreased polyester yarn; First washing: Rinse the degreased polyester yarn thoroughly with clean water to remove the residual degreaser and emulsified oil; Dyeing: After washing, the yarn is dyed in a dye vat with disperse scarlet dye, 0.5g / l glacial acetic acid and 1.5g / l strong dispersing leveling agent, with the disperse dye content owf ≤ 0.3% in the dye vat and a bath ratio of 1:8. The temperature rise process in the dyeing process is that the temperature in the dye vat is directly raised from room temperature to 80°C and maintained for 10 minutes, then raised to 110°C at a rate of 0.8°C / min and maintained for 10 minutes, then raised to 130°C at a rate of 1°C / min and maintained for 20 minutes; High temperature drainage: After drainage, remove the dyed polyester fabric from the dyeing solution; Post-treatment reduction cleaning: immerse the dyed polyester yarn in water, then heat it to 80℃ and keep it for 10 minutes; rinse the polyester yarn with plenty of clean water until the water is clear; Oiling: immerse the polyester yarn after reduction cleaning in water, add 1.5 parts by mass of hydrophilic softener, 1.5 parts by mass of silicone oil, 1 part by mass of strong antistatic agent and 1.2 parts by mass of anti-phenol yellowing agent, then control the temperature at 50°C, adjust the speed of the oiling machine to fix the oil on the yarn, and then let the yarn cool naturally; Second wash: remove excess oil and floating color; Dehydration: Use a centrifugal dehydrator to remove moisture from the yarn; Drying: The yarn is evenly heated and dried in an oven, and finally a light pink enzyme-recovered polyester yarn is obtained.

[0010] Example 2: Preparation of green polyester yarn; Preparation, loosening of the tube, and entry into the dye vat are the same as in Example 1; Pre-treatment degreasing: Pre-treatment degreasing is to pre-treat the bobbin yarn with 30g of degreasing agent in the same bath at a bath ratio of 1:8, and then the temperature is raised to 90°C at room temperature and maintained for 20 minutes to obtain degreased polyester yarn; The first washing is the same as in Example 1; Dyeing: After washing, the yarn is dyed in a dye vat with disperse turquoise dye, 0.5g / l glacial acetic acid and 1.5g / l strong dispersing leveling agent, the disperse dye content in the dye vat is 2%, and the bath ratio is 1:8. The temperature rise process in the dyeing process is that the temperature in the dye vat is directly raised from room temperature to 80°C and maintained for 10 minutes, and then heated to 110°C at a rate of 0.8°C / min and maintained for 10 minutes, and then heated to 130°C at a rate of 1°C / min; and maintained for 20 minutes; High temperature drainage is the same as in Example 1; Post-treatment reduction cleaning: immerse the dyed polyester yarn in water, add 1.5g / l hydrosulfite, 1g / l caustic soda and 1g / l glacial acetic acid, then heat to 80°C and keep for 20 minutes; rinse the polyester yarn with plenty of clean water until the water is clear; Oiling: immerse the polyester yarn after reduction cleaning in water, add 1.5 parts by mass of hydrophilic softener, 1.5 parts by mass of silicone oil, 1 part by mass of strong antistatic agent and 1.2 parts by mass of anti-phenol yellowing agent, then control the temperature at 50°C, adjust the speed of the oiling machine to fix the oil on the yarn, and then let the yarn cool naturally; The second washing, dehydration and drying are the same as those in Example 1, and finally the green polyester yarn is obtained.

[0011] Example 3: Preparation of dark blue polyester yarn; Preparation, loosening of the tube, and entry into the dye vat are the same as in Example 1; Pre-treatment degreasing: Pre-treatment degreasing is to pre-treat the bobbin yarn with 30g of degreasing agent in the same bath at a bath ratio of 1:8, and then the temperature is raised to 90°C at room temperature and maintained for 20 minutes to obtain degreased polyester yarn; The first washing is the same as in Example 1; Dyeing: After washing, the yarn is dyed in a dye vat with dispersed navy dye, 0.5g / l glacial acetic acid and 1.5g / l strong dispersing leveling agent, the disperse dye content in the dye vat is 4%, and the bath ratio is 1:8. The temperature rise process in the dyeing process is that the temperature in the dye vat is directly raised from room temperature to 80°C and maintained for 10 minutes, then raised to 110°C at a rate of 0.8°C / min and maintained for 10 minutes, then raised to 130°C at a rate of 1°C / min; and maintained for 20 minutes; High temperature drainage is the same as in Example 1; Post-treatment reduction cleaning: immerse the dyed polyester yarn in water, add 3g / l hydrosulfite, 2g / l caustic soda and 1g / l glacial acetic acid, then heat to 80°C and keep for 20 minutes; rinse the polyester yarn with plenty of clean water until the water is clear; Oiling: immerse the polyester yarn after reduction cleaning in water, add 1.5 parts by mass of hydrophilic softener, 1.5 parts by mass of silicone oil, 1 part by mass of strong antistatic agent and 1 part by mass of anti-phenol yellowing agent, then control the temperature at 50°C, adjust the speed of the oiling machine to fix the oil on the yarn, and then let the yarn cool naturally; The second washing, dehydration and drying are the same as those in Example 1, and finally a dark blue polyester yarn is obtained.

[0012] Comparative Example 1 is basically the same as Example 1, and finally a light pink polyester yarn is obtained, except that in the preparation process, the yarn used is a petroleum-based polyester yarn; Comparative Example 2 is basically the same as Example 2, and finally obtains green polyester yarn, except that in the preparation process, the yarn used is petroleum-based polyester yarn; Comparative Example 3 is basically the same as Example 3, and finally obtains dark blue polyester yarn, except that in the preparation process, the yarn used is petroleum-based polyester yarn; Comparative Example 4 is basically the same as Example 1, and finally a light pink polyester yarn is obtained. The difference is that in the preparation process, the yarn used is chemically recycled polyester yarn; Comparative Example 5 is basically the same as Example 2, and finally obtains green polyester yarn, except that in the preparation process, the yarn used is chemically recycled polyester yarn; Comparative Example 6 is basically the same as Example 3, and finally obtains dark blue polyester yarn, except that in the preparation process, the yarn used is chemically recycled polyester yarn; According to GB / T 14343-2008 "Test method for linear density of chemical yarn filaments", GB / T 14344-2022 "Test method for tensile properties of chemical yarn filaments", GB / T 3920-2008 "Textiles - Tests for color fastness - Color fastness to rubbing", GB / T3921-2008 "Textiles - Tests for color fastness - Color fastness to soaping", GB / T 3922-2013 "Textiles - Tests for color fastness - Color fastness to perspiration", and ASTM D1148 "Textiles - Test Standard and Test Method for Yellowing Resistance", the physical properties and color fastness of the dyed yarn are tested. The physical properties of the dyed yarn are shown in Table 1, and the chemical properties of the corresponding polyester yarn after dyeing are shown in Table 2; Table 1:

[0013] Table 2:

[0014] It can be seen from the table that the breaking strength of the polyester yarn after chemical regeneration and enzyme recovery after dyeing of the present invention is lower than that of the petroleum-based polyester yarn. Under the same high temperature and high pressure conditions, the polyester yarn after enzyme recovery has almost no difference in physical and chemical properties with the petroleum-based polyester yarn and the chemically recycled polyester yarn, and meets the use standards of textiles for yarns; the dyeing process has high flexibility, and the type, concentration and dyeing conditions of the dye can be adjusted according to different needs to meet the production requirements of different textiles; After testing and comparison, it was found that the physical and chemical properties of the enzyme-recovered polyester yarn after dyeing using the dyeing process of the present invention were comparable to those of conventional petroleum-based polyester yarn and chemically recycled polyester yarn, meeting the yarn usage standards for textiles.

[0015] In the present invention: For insufficient color fastness: In the pre-treatment degreasing process, by using a specific heating temperature (80-90℃) for 15-25 minutes, and using 25-35g of the same-bath degreasing agent and a bath ratio of 1:5-10, the oil and impurities on the yarn can be completely removed, providing a clean surface for the subsequent penetration and combination of dyes. In the dyeing process, the amount of disperse dyes, 0.2-1g / l glacial acetic acid and 1-3g / l strong dispersing leveling agent is accurately controlled, and a bath ratio of 1:5-10 and a specific heating program are set (starting from room temperature to 75-85℃ and maintaining for 5-15 minutes, then heating to 105-115℃ at a rate of 0.5-1℃ / min and maintaining for 5-15 minutes, and then heating to 125-135℃ at a rate of 0.5-2℃ / min and maintaining for 15-20 minutes). 25 minutes), so that the dye can evenly and fully penetrate into the yarn and form a solid bond with the yarn fibers, thus significantly improving color fastness; To reduce the yellowing resistance: In the oiling process, 1-2 parts by mass of anti-phenol yellowing agent is introduced. The anti-phenol yellowing agent can form a stable protective film on the surface of the yarn, effectively blocking the erosion of the yarn by external factors such as oxygen and ultraviolet rays, thereby significantly enhancing the anti-yellowing ability of the yarn, extending the service life of the product and maintaining a good appearance; In response to environmental challenges: The entire dyeing process has been precisely optimized in terms of auxiliaries selection and dosage. For example, in the pre-treatment degreasing and dyeing processes, the types and dosages of auxiliaries are strictly controlled to reduce the use of unnecessary chemicals. At the same time, reasonable temperature and time control, such as precise heating rate and holding time, reduces energy consumption while ensuring the dyeing effect. These measures not only reduce the chemical pollution load of wastewater, but also reduce carbon emissions in the production process, which meets environmental protection requirements and the concept of sustainable development; Regarding the lack of adaptability: the parameter settings of each process in the present invention have great flexibility, such as the temperature and time range of pre-treatment degreasing, the dosage range of dyes in the dyeing process, the adjustability of the heating program, etc., which can be adjusted according to the characteristics of enzyme-recovered polyester yarns of different types and specifications. By flexibly adjusting the process parameters, it is possible to adapt to the differences in yarn surface properties and internal structures, ensuring that different types of yarns can obtain stable, consistent and high-quality dyeing effects.

[0016] The present invention has the following significant advantages: Environmental Protection and Sustainability: Focusing on enzyme recycling of polyester yarn, it significantly reduces textile waste, promotes resource recycling, and reduces dependence on virgin petroleum resources; High dyeing efficiency: In the pre-treatment degreasing stage, the same-bath degreasing agent is used, and the bath ratio is controlled at 1:5-10, which effectively reduces the water consumption. At the same time, the room temperature is raised to 80-90℃ and maintained for 15-25 minutes, completing the degreasing process quickly and efficiently. During the dyeing process, the temperature is gradually raised from room temperature to 125-135°C and maintained for 15-25 minutes. Compared with the traditional process, the dyeing time is shortened and the production efficiency is improved; Excellent dyeing effect and color fastness: The specific heating rate and temperature holding time ensure the uniform diffusion and penetration of the dye in the yarn, and the yarn is bright and uniform in color after dyeing; The use of strong dispersing and leveling agents helps to improve the bonding strength between dye and yarn. After testing, the color fastness is excellent and meets or exceeds industry standards; Enhanced anti-yellowing ability: A special anti-phenol yellowing agent is added to effectively prevent the yarn from yellowing under light or high temperature environment, extending the service life and appearance of the product; according to experimental data, after adding the anti-phenol yellowing agent, the anti-yellowing performance of the yarn is improved; Flexibility in process parameters: The temperature, time, bath ratio and other parameters in the dyeing process can be adjusted according to actual needs to adapt to different types and specifications of enzyme-recycled polyester yarns, which enhances the flexibility and adaptability of the process; Excellent physical and chemical properties: The physical and chemical properties of the enzyme-recycled polyester yarn after dyeing are comparable to those of the ordinary petroleum-based recycled polyester yarn and the chemically recycled polyester yarn after dyeing. Indicators such as tensile strength, abrasion resistance, and color fastness all meet the standards for textile use, ensuring the quality and stability of the product. Energy saving and emission reduction: Due to the refined design of the entire dyeing process in terms of temperature control, time optimization and use of auxiliaries, compared with traditional processes, it significantly reduces energy consumption and chemical consumption, reduces wastewater discharge, and meets the requirements of green production and energy conservation and emission reduction; In summary, the enzyme-recovered polyester yarn dyeing process involved in this application shows significant advantages in environmental protection, dyeing efficiency, dyeing effect, color fastness, anti-yellowing ability, process flexibility, energy saving and emission reduction, etc., providing strong support for the green development and transformation and upgrading of the textile industry.

[0017] Finally, it should be noted that the above examples are only some specific examples of the present invention. Obviously, the present invention is not limited to the above examples, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A dyeing process for polyester yarn based on enzyme recovery, characterized in that: The process includes the following steps: preparation, yarn loosening, feeding into the cylinder, pre-treatment degreasing, first water washing, dyeing, high temperature drainage, post-treatment reduction cleaning, oiling, second water washing, dehydration and drying: in, In the pre-treatment degreasing process, the yarn after entering the cylinder is heated to 80-90°C at room temperature and maintained for 15-25 minutes, and treated with 25-35g of degreasing agent in the same bath with a bath ratio of 1:5-10; In the dyeing process, the yarn after washing is dyed in a dyeing vat according to disperse dyes, 0.2-1g / l glacial acetic acid and 1-3g / l strong dispersing leveling agent. The disperse dye owf content in the dyeing vat is 0.3-4%, and the bath ratio is 1:5-10. During the dyeing process, the temperature in the dyeing vat is heated from room temperature to 75-85°C and maintained for 5-15 minutes, then heated to 105-115°C at a rate of 0.5-1°C / min and maintained for 5-15 minutes, and then heated to 125-135°C at a rate of 0.5-2°C / min and maintained for 15-25 minutes to complete the dyeing; In the oiling process, the yarn after reduction cleaning is immersed in water, the temperature is controlled at 30-50°C, the speed of the oiling machine is adjusted to fix the oil on the yarn, and then it is cooled naturally; the oil is composed of 1-2 parts by mass of a hydrophilic softener, 1-2 parts by mass of silicone oil, 1-2 parts by mass of a strong antistatic agent and 1-2 parts by mass of an anti-phenol yellowing agent.

2. A dyeing process for polyester yarn based on enzyme recovery according to claim 1, characterized in that: The specific steps are as follows: a) Preparation: Prepare the enzyme-recovered polyester yarn to be dyed; b) Yarn loosening: placing the polyester yarn on a cone loosening machine for yarn loosening; c) Entering the dyeing vat: Put the loosened polyester yarn into the yarn loading frame of the dyeing vat to form a bobbin yarn; d) Pre-treatment degreasing: The yarn is heated to 80-90°C at room temperature and maintained for 15-25 minutes, and treated with 25-35g of degreasing agent and a bath ratio of 1:5-10 to obtain degreased polyester yarn; e) First washing: The deoiled polyester yarn is thoroughly rinsed with clean water to remove the residual deoiling agent and emulsified oil stains in the same bath, thereby obtaining the polyester yarn after the first washing; f) Dyeing: Add disperse dye, 0.2-1g / l glacial acetic acid and 1-3g / l strong dispersing leveling agent into the dye vat, dye the polyester yarn after the first washing according to the disperse dye owf content of 0.3-4% and the bath ratio of 1:5-10. During the dyeing process, the temperature in the dye vat is heated from room temperature to 75-85°C and maintained for 5-15 minutes, then heated to 105-115°C at a rate of 0.5-1°C / min and maintained for 5-15 minutes, and then heated to 125-135°C at a rate of 0.5-2°C / min and maintained for 15-25 minutes to complete the dyeing; g) High-temperature drainage: After dyeing is completed, drain the water in the dyeing tank and fish out the dyed polyester yarn; h) Post-treatment reduction cleaning: immerse the dyed polyester yarn in water, add a reducing agent, heat it to 80-90°C and keep it for 10-20 minutes, then rinse it with a large amount of clean water until the water is clear, and obtain the polyester yarn after reduction cleaning; i) Oiling: immerse the polyester yarn after reduction cleaning in water, control the temperature at 30-50°C, adjust the speed of the oiling machine to fix the oil on the yarn, and then cool it naturally; the oil is composed of 1-2 parts by mass of a hydrophilic softener, 1-2 parts by mass of silicone oil, 1-2 parts by mass of a strong antistatic agent and 1-2 parts by mass of an anti-phenol yellowing agent; j) Second washing: After cooling, rinse the polyester yarn thoroughly with clean water to remove excess oil and floating matter; k) Dehydration: The polyester yarn after the second washing is placed in a centrifugal dehydrator for dehydration; l) Drying: The dehydrated polyester yarn is evenly heated and dried in an oven to finally obtain the desired polyester yarn.

3. A dyeing process for polyester yarn based on enzyme recovery according to claim 2, characterized in that: In the step a), the specification of the polyester yarn is 150D / 36F DTY.

4. The dyeing process of polyester yarn based on enzyme recovery according to claim 2, characterized in that: In the step a), the polyester yarn also includes petroleum-based polyester yarn or chemically recycled polyester yarn.

5. The dyeing process of polyester yarn based on enzyme recovery according to claim 2, characterized in that: In the step h), the reducing agent is composed of 1-3 g / l sodium hypochlorite, 1-3 g / l caustic soda and 0.5-2 g / l glacial acetic acid.

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