A method for regenerating polyester waste yarn and obtained regenerated fiber

Abstract

The present application relates to the field of waste silk regeneration, and specifically discloses a polyester waste silk regeneration method and the obtained regenerated fiber, the regeneration method comprising the following steps: S1, washing, drying and crushing the polyester waste silk to obtain polyester waste; S2, mixing the polyester waste silk with modified polyacrylonitrile fiber in a mass ratio of 1: (0.2-0.5), then adding a viscosity enhancer and an anti-thermal decomposition auxiliary agent to mix, and melt spinning; S3, cooling and oiling, winding and bundling, drawing, curling and cutting to obtain regenerated fiber; wherein, in step S2, the modified polyacrylonitrile fiber is obtained by immersing the polyacrylonitrile fiber in a modifying solution and then heat-treating it, and the modifying solution is obtained by mixing a cross-linking agent, aminopyridine-modified porous carbon powder and a solvent; the present application also discloses the regenerated fiber obtained by the above method, and the present application has the characteristics of improving the quality and performance of the fiber prepared by regenerating waste silk.

Description

Technical Field

[0001] The present application relates to the field of waste silk regeneration, and more specifically, to a method for regenerating polyester waste silk and the resulting regenerated fiber. Background Art

[0002] Recycled polyester fiber is made from recycled polyester bottle flakes, polyester blocks, and polyester yarn waste. The flakes are crushed and cleaned, and the resulting mixture is dried, melt-extruded, spun, wound, bundled, drawn, crimped, relaxed, heat-set, and cut into polyester fibers of varying lengths. Recycled polyester fully utilizes renewable resources and has a broad market due to its low cost and excellent performance.

[0003] Recycled polyester production methods are primarily categorized by physical and chemical methods, depending on the principle of regeneration. The physical method involves directly melt-spinning recycled polyester waste materials after sorting, cleaning, and drying. The chemical method involves depolymerizing recycled polyester into monomers or intermediates through chemical reactions, followed by purification and separation, followed by regeneration, polymerization, and melt spinning. The physical method is currently the dominant method for polyester regeneration due to its simple production technology, straightforward process, and low production costs.

[0004] However, physical regeneration belongs to downgraded regeneration, so it is impossible to prepare qualified regenerated polyester by simply melt extrusion of polyester waste. One of the reasons is that polyester waste yarn will undergo thermal decomposition during the melt extrusion process, resulting in a decrease in the strength and other properties of the final regenerated polyester fiber, which cannot meet the requirements. In addition, thermal decomposition in the process leads to a decrease in viscosity, and problems such as broken ends and hairy yarns are prone to occur during spinning, affecting the spinning efficiency. Therefore, improving the quality of recycled polyester melt is the core link in the physical regeneration process. How to improve the performance of the final regenerated polyester fiber to meet the requirements is a problem that needs to be solved urgently in the regeneration of polyester waste yarn. Summary of the Invention

[0005] In order to improve the quality and performance of fibers produced by regenerating waste silk, the present application provides a method for regenerating polyester waste silk and the resulting regenerated fibers.

[0006] In a first aspect, the present application provides a method for regenerating polyester waste yarn, which adopts the following technical solution:

[0007] A method for regenerating polyester waste yarn comprises the following steps:

[0008] S1. Washing, drying, and crushing polyester waste to obtain polyester waste;

[0009] S2, mixing polyester waste and modified polyacrylonitrile fiber in a mass ratio of 1: (0.2-0.5), then adding a tackifier and an anti-thermal decomposition additive, mixing, and melt spinning;

[0010] S3, cooling and oiling, winding and bundling, drawing, crimping and cutting to obtain regenerated fiber;

[0011] Wherein, in step S2, the modified polyacrylonitrile fiber is prepared by immersing the polyacrylonitrile fiber in a modifying solution and then heat-treating it. The modifying solution is prepared by mixing a cross-linking agent, aminopyridine-modified porous carbon powder and a solvent.

[0012] By adopting the above technical solution, in this application, the polyester waste is first cleaned, dried and crushed, and then modified polyacrylonitrile fiber, tackifier and anti-thermal decomposition auxiliary agent are added during the melt spinning process. The modified polyacrylonitrile fiber and polyester waste are mixed and spun to significantly improve the strength and wear resistance of the regenerated polyester, thereby expanding the application range of the regenerated polyester fiber in the fields of textiles, industrial cloths, etc., and more importantly, the polyacrylonitrile fiber has good thermal stability. It is co-spun with polyester waste to increase the heat-resistant temperature of the overall fiber and alleviate the viscosity reduction and performance degradation caused by high-temperature degradation during the melt spinning of polyester waste. A small amount of tackifier and anti-thermal decomposition auxiliary agent are added to adjust the viscosity to improve the spinning efficiency and quality, and alleviate the performance degradation caused by degradation during the melt spinning process.

[0013] In the present application, the modified polyacrylonitrile fiber is prepared by impregnating the polyacrylonitrile fiber in a mixed solution of a crosslinking agent and aminopyridine-modified porous carbon powder. The amino group in the aminopyridine reacts with the cyano group on the polyacrylonitrile fiber to form an amide bond, thereby realizing crosslinking modification of the porous carbon powder and the polyacrylonitrile fiber. The introduction of the porous carbon powder further improves the heat resistance and strength of the polyacrylonitrile fiber, thereby improving the heat resistance and strength mechanical properties of the composite fiber of the polyacrylonitrile fiber and polyester waste yarn, and improving the performance of the regenerated fiber. Moreover, the modified polyacrylonitrile fiber forms an amide functional group, which can react with the polyester end group in the polyester waste yarn to form a new chemical bond, and thus it is found that it can also have a thickening effect. When a small amount of thickener is added, the thickening process during the melt extrusion process can be significantly achieved, and there are no problems such as broken ends and hairy yarns during the spinning process, which significantly improves the spinning efficiency and the performance of the spinning product, and finally produces a regenerated fiber with better performance, broadening its application field.

[0014] Optionally, the aminopyridine-modified porous carbon powder is prepared by the following method:

[0015] 1) The coffee grounds are cleaned, dried, crushed and ground to obtain coffee powder, which is then immersed in a nitric acid solution and then carbonized at high temperature under an inert gas atmosphere. The porous carbon powder is then screened, crushed, washed and dried.

[0016] 2) The porous carbon powder prepared in step 1) is immersed in a solution containing aminopyridine for reaction, and then filtered, washed and dried to obtain aminopyridine-modified porous carbon powder.

[0017] By adopting the above-mentioned technical scheme, in this application, coffee grounds are ground to obtain a carbon source, which is then immersed in a hydrochloric acid solution to etch the carbon source. Then, during the high-temperature carbonization and activation process, the nitric acid activator on the carbon source reacts with the surface of the porous carbon powder to introduce oxygen-containing functional groups such as hydroxyl groups. In addition, non-carbon elements are removed during the high-temperature carbonization process to form a porous carbon powder with a porous structure, and hydroxyl functional groups are introduced. Then, it is immersed in an aminopyridine-containing solution, and the amino group reacts with the hydroxyl group to achieve cross-linking of aminopyridine and hydroxyl porous carbon powder. Amino groups and pyridine rings are introduced into the porous carbon powder. The introduction of pyridine rings further enhances the high-temperature resistance and strength of polyacrylonitrile fibers, and an amide bond is formed between the amino group and the polyacrylonitrile fiber, which then reacts with the polyester end group in the polyester waste yarn to form a macromolecular structure, thereby increasing the viscosity while improving its heat resistance and mechanical strength.

[0018] Optionally, when preparing aminopyridine-modified porous carbon powder, the aminopyridine in step 2) is selected from one or both of 2,6-diaminopyridine and 3,5-diaminopyridine.

[0019] By adopting the above technical solution, when aminopyridine is selected from the above substances, it contains two amino groups, and the porous carbon powder is introduced and grafted onto the polyacrylonitrile fiber through the amino groups, thereby achieving the purpose of modifying the polyacrylonitrile fiber to improve the heat resistance and mechanical properties.

[0020] Optionally, when preparing aminopyridine-modified porous carbon powder, the carbonization temperature in step 1) is 720-800° C., and the carbonization time is 2-4 h.

[0021] By adopting the above technical solution, the coffee grounds are soaked and then carbonized at high temperature, and impurities are removed during the carbonization process to form porous carbon powder.

[0022] Optionally, when preparing aminopyridine-modified porous carbon powder, the aminopyridine-containing solution in step 2) is prepared by mixing aminopyridine and water in a mass ratio of 1:(6-8), and the porous carbon powder and the aminopyridine-containing solution are added in a mass ratio of 1:(5-6).

[0023] Optionally, when preparing aminopyridine-modified porous carbon powder, the immersion temperature in step 2) is 35-45° C., and the immersion time is 2-3 h.

[0024] By adopting the above technical solution and using the above temperature, time and ratio for impregnation, the aminopyridine-modified porous starch has a better modification effect on polyacrylonitrile fibers.

[0025] Optionally, the modified polyacrylonitrile fiber is prepared by the following method:

[0026] A cross-linking agent is mixed with dimethylformamide, and then aminopyridine-modified porous carbon powder is added to obtain a modified solution. Then, polyacrylonitrile fiber is added to the modified solution, immersed at 65-70°C for 1-2 hours, heat-treated at 80-100°C for 2-3 hours, and then washed and dried to obtain modified polyacrylonitrile fiber.

[0027] The cross-linking agent is glutaraldehyde and organic peroxide in a mass ratio of 1: (1.5-2);

[0028] The amount of crosslinking agent added is 3-5wt% of the amount of polyacrylonitrile fiber added, the amount of aminopyridine modified porous carbon powder added is 15-20wt% of the amount of polyacrylonitrile fiber added, and the amount of dimethylformamide added is 6-8 times by weight of the amount of polyacrylonitrile fiber added.

[0029] By adopting the above technical solution, a crosslinking agent is mixed with a dimethylformamide solvent, and then aminopyridine-modified porous carbon powder is added to prepare a modified solution. Polyacrylonitrile fiber is immersed in the above modified solution, and glutaraldehyde forms chemical crosslinks with amino groups in the polyacrylonitrile fiber and the aminopyridine-modified porous carbon powder. The modification of the polyacrylonitrile fiber by the aminopyridine-modified porous carbon powder is achieved through glutaraldehyde and an organic peroxide crosslinking agent.

[0030] Optionally, in step S2, the tackifier is 1,4-butanediol diglycidyl ether, and the amount of the tackifier added is 0.1-0.5 wt % of the polyester waste.

[0031] By adopting the above technical solution, 1,4-butanediol diglycidyl ether is selected as a thickener. The molecular structure contains two epoxy groups and a longer methylene chain, which realizes an addition reaction with the polyester end group, thereby achieving the purpose of thickening. It can also improve the flexibility and fluidity of the polyester chain, which is more conducive to the spinning process. Moreover, adding a small amount of thickener in this application can play a good viscosity regulating role, alleviating the problem of reduced spinning efficiency and quality due to reduced viscosity due to high-temperature degradation of the melt.

[0032] Optionally, in step S2, the anti-thermal decomposition auxiliary agent is selected from di-n-butyltin dilaurate and triphenyl phosphite in a mass ratio of 1: (1.8-2.2), and the added amount of the anti-thermal decomposition auxiliary agent is 1-3wt% of the polyester waste.

[0033] By adopting the above technical solution, triphenyl phosphite is used as an organic phosphate stabilizer to effectively inhibit the degradation and oxidation of the polyester chain and improve thermal stability. Di-n-butyltin dilaurate not only acts as a thermal stabilizer but also plays a certain catalytic role, promoting the addition of the thickener to the end group of the polyester chain, thereby reducing the degradation of polyester waste during the melting process, alleviating the reduction in viscosity and mechanical properties, and improving the final spinning efficiency and product performance.

[0034] In a second aspect, the present application provides a regenerated fiber, which adopts the following technical solution:

[0035] A regenerated fiber is prepared by the polyester waste yarn regeneration method.

[0036] By adopting the above technical solution, the regenerated fiber prepared by the polyester waste yarn regeneration method of the present application has excellent properties such as strength, thermal stability and wear resistance, and realizes the recycling of polyester waste yarn and the reuse of resources.

[0037] In summary, this application has the following beneficial effects:

[0038] 1. In this application, the mixed spinning of modified polyacrylonitrile fiber and polyester waste yarn significantly improves the strength and wear resistance of regenerated polyester, thereby expanding the application range of regenerated polyester fiber in textiles, industrial fabrics and other fields. More importantly, polyacrylonitrile fiber has good thermal stability. Co-spinning it with polyester waste yarn can improve the heat resistance temperature of the overall fiber and alleviate the viscosity reduction and performance degradation caused by high-temperature degradation of polyester waste yarn during melt spinning. A small amount of thickener and anti-thermal decomposition additive is then added to adjust the viscosity to improve spinning efficiency and quality, and alleviate the performance degradation caused by degradation during the melt spinning process;

[0039] 2. In the present application, the modified polyacrylonitrile fiber is prepared by impregnating the polyacrylonitrile fiber in a mixed solution of a crosslinking agent and aminopyridine-modified porous carbon powder. The amino group in the aminopyridine reacts with the cyano group on the polyacrylonitrile fiber to form an amide bond, thereby realizing the crosslinking modification of the porous carbon powder and the polyacrylonitrile fiber. The introduction of the porous carbon powder further improves the heat resistance and strength of the polyacrylonitrile fiber, thereby improving the heat resistance and strength mechanical properties of the composite fiber of the polyacrylonitrile fiber and polyester waste yarn, and improving the performance of the regenerated fiber. Moreover, the modified polyacrylonitrile fiber forms an amide functional group, which can react with the polyester end group in the polyester waste yarn to form a new chemical bond, and thus it is found that it can also have a thickening effect. When a small amount of thickener is added, the thickening process in the melt extrusion process can be significantly realized, and there are no problems such as broken ends and hairy yarns during the spinning process, which significantly improves the spinning efficiency and the performance of the spinning product, and finally produces a regenerated fiber with better performance, broadening its application field. DETAILED DESCRIPTION

[0040] The present application is further described in detail below with reference to the examples. It is particularly noted that if no specific conditions are specified in the following examples, the reactions are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following examples can be obtained from common commercial sources.

[0041] The following preparation example is a preparation example of modified polyacrylonitrile fiber

[0042] Preparation Example 1

[0043] A method for preparing modified polyacrylonitrile fiber comprises the following steps:

[0044] Step 1: preparing aminopyridine-modified porous carbon powder, specifically comprising the following steps:

[0045] 1) Clean the coffee grounds to remove impurities such as plastic and paper scraps, then dry them at 80°C for 2.5 hours, and grind them to obtain coffee powder with a particle size of 800-1000 mesh;

[0046] Then, the coffee powder was immersed in a nitric acid solution with a mass concentration of 45% for 1.5 hours, and the amount of nitric acid solution added was 9 times the mass of the coffee powder;

[0047] The soaked coffee powder is then carbonized at a high temperature of 760°C for 3 hours under an inert gas atmosphere. The powder is then screened to remove large particles of impurities, crushed, washed, and dried to produce porous carbon powder.

[0048] 2) The porous carbon powder prepared in step 1) is immersed in a solution containing aminopyridine for reaction at a temperature of 40° C. for 2.5 h, and then filtered, washed and dried to obtain aminopyridine-modified porous carbon powder;

[0049] The aminopyridine-containing solution is prepared by mixing 2,6-diaminopyridine and water in a mass ratio of 1:7, and the porous carbon powder and the aminopyridine-containing solution are added in a mass ratio of 1:5.5;

[0050] Step 2: preparing modified polyacrylonitrile fiber, the specific operation includes the following steps:

[0051] Taking 1 kg of polyacrylonitrile fiber as the treatment basis, a crosslinking agent and dimethylformamide are mixed, and then the aminopyridine-modified porous carbon powder prepared in step 1 is added, and the mixture is mixed to obtain a modified solution, wherein the crosslinking agent is selected from glutaraldehyde and dicumyl peroxide in a mass ratio of 1:1.8, the amount of the crosslinking agent added is 4wt% of the amount of the polyacrylonitrile fiber added, the amount of the aminopyridine-modified porous carbon powder added is 18wt% of the amount of the polyacrylonitrile fiber added, and the amount of dimethylformamide added is 7 times the mass of the amount of the polyacrylonitrile fiber added;

[0052] The polyacrylonitrile fiber was added into the modification solution, immersed at 65°C for 2 hours, heat-treated at 90°C for 2.5 hours, and then washed and dried to obtain the modified polyacrylonitrile fiber.

[0053] Preparation Example 2

[0054] A method for preparing modified polyacrylonitrile fiber comprises the following steps:

[0055] Step 1: preparing aminopyridine-modified porous carbon powder, specifically comprising the following steps:

[0056] 1) Clean the coffee grounds to remove impurities such as plastic and paper scraps, then dry them at 75°C for 3 hours, and grind them to obtain coffee powder with a particle size of 800-1000 mesh;

[0057] Then, the coffee powder was immersed in a 40% nitric acid solution for 1 hour, and the amount of nitric acid solution added was 8 times the mass of the coffee powder;

[0058] The soaked coffee powder is then carbonized at 720°C for 4 hours under an inert gas atmosphere. The powder is then screened to remove large particles of impurities, crushed, washed, and dried to produce porous carbon powder.

[0059] 2) The porous carbon powder prepared in step 1) is immersed in a solution containing aminopyridine for reaction at a temperature of 35° C. for 3 h, and then filtered, washed and dried to obtain aminopyridine-modified porous carbon powder;

[0060] The aminopyridine-containing solution is prepared by mixing 2,6-diaminopyridine and water in a mass ratio of 1:6, and the porous carbon powder and the aminopyridine-containing solution are added in a mass ratio of 1:5;

[0061] Step 2: preparing modified polyacrylonitrile fiber, the specific operation includes the following steps:

[0062] Taking 1 kg of polyacrylonitrile fiber as the treatment basis, a crosslinking agent and dimethylformamide are mixed, and then the aminopyridine-modified porous carbon powder prepared in step 1 is added, and the mixture is mixed to obtain a modified solution, wherein the crosslinking agent is selected from glutaraldehyde and dicumyl peroxide in a mass ratio of 1:1.5, the amount of the crosslinking agent added is 3wt% of the amount of the polyacrylonitrile fiber added, the amount of the aminopyridine-modified porous carbon powder added is 15wt% of the amount of the polyacrylonitrile fiber added, and the amount of dimethylformamide added is 6 times the mass of the amount of the polyacrylonitrile fiber added;

[0063] The polyacrylonitrile fiber was added into the modification solution, immersed at 65°C for 2 hours, heat-treated at 80°C for 3 hours, and then washed and dried to obtain the modified polyacrylonitrile fiber.

[0064] Preparation Example 3

[0065] A method for preparing modified polyacrylonitrile fiber comprises the following steps:

[0066] Step 1: preparing aminopyridine-modified porous carbon powder, specifically comprising the following steps:

[0067] 1) Clean the coffee grounds to remove impurities such as plastic and paper scraps, then dry them at 85°C for 2 hours, and grind them to obtain coffee powder with a particle size of 800-1000 mesh;

[0068] Then, the coffee powder was immersed in a 50% nitric acid solution for 2 hours, and the amount of nitric acid solution added was 10 times the mass of the coffee powder;

[0069] The soaked coffee powder is then carbonized at a high temperature of 800°C for 2 hours under an inert gas atmosphere. The powder is then screened to remove large particles of impurities, crushed, washed, and dried to produce porous carbon powder.

[0070] 2) The porous carbon powder prepared in step 1) is immersed in a solution containing aminopyridine for reaction at a temperature of 45° C. for 2 h, and then filtered, washed and dried to obtain aminopyridine-modified porous carbon powder;

[0071] The aminopyridine-containing solution is prepared by mixing 2,6-diaminopyridine and water in a mass ratio of 1:8, and the porous carbon powder and the aminopyridine-containing solution are added in a mass ratio of 1:6;

[0072] Step 2: preparing modified polyacrylonitrile fiber, the specific operation includes the following steps:

[0073] Taking 1 kg of polyacrylonitrile fiber as the treatment basis, a crosslinking agent and dimethylformamide are mixed, and then the aminopyridine-modified porous carbon powder prepared in step 1 is added, and the mixture is mixed to obtain a modified solution, wherein the crosslinking agent is selected from glutaraldehyde and dicumyl peroxide in a mass ratio of 1:2, the amount of the crosslinking agent added is 5wt% of the amount of the polyacrylonitrile fiber added, the amount of the aminopyridine-modified porous carbon powder added is 20wt% of the amount of the polyacrylonitrile fiber added, and the amount of dimethylformamide added is 8 times the mass of the amount of the polyacrylonitrile fiber added;

[0074] The polyacrylonitrile fiber was added into the modification solution, immersed at 70°C for 1 hour, heat-treated at 100°C for 2 hours, and then washed and dried to obtain the modified polyacrylonitrile fiber.

[0075] Preparation Example 4

[0076] A method for preparing modified polyacrylonitrile fiber is carried out according to the method in Preparation Example 1, except that an equal amount of 2,6-diaminopyridine is replaced by 2-aminopyridine.

[0077] Comparative Preparation Example 1

[0078] A method for preparing modified polyacrylonitrile fiber is carried out according to the method in Preparation Example 1, except that when preparing the modified polyacrylonitrile fiber, the aminopyridine-modified porous carbon powder is directly replaced with an equal amount of the porous carbon powder prepared in step 1).

[0079] Comparative Preparation Example 2

[0080] A method for preparing modified polyacrylonitrile fiber is carried out according to the method in Preparation Example 1, except that when preparing the modified polyacrylonitrile fiber, the aminopyridine-modified porous carbon powder is directly replaced with an equal amount of 2,6-diaminopyridine.

[0081] The polyester waste yarns in the following embodiments are polyester spinning waste yarns, more specifically, the discharge yarns from the spinning room, and the drawn waste yarns from the winding and post-processing sections.

[0082] Example 1

[0083] A method for regenerating polyester waste yarn comprises the following steps:

[0084] S1. Washing, drying, and crushing polyester waste to obtain polyester waste;

[0085] S2. Using 1 kg of polyester waste as the treatment basis, the polyester waste was mixed with the modified polyacrylonitrile fiber prepared in Preparation Example 1 at a mass ratio of 1:0.3, and the mixture was placed in a reactor. The temperature was raised to 320° C., and then a tackifier and an anti-thermal decomposition aid were added and mixed. The mixture was stirred at 320° C. for 100 minutes to melt, and then the molten polyester material was extruded through a spinneret for spinning;

[0086] The tackifier is 1,4-butanediol diglycidyl ether, and the amount of the tackifier added is 0.3wt% of the polyester waste; the anti-thermal decomposition auxiliary agent is di-n-butyltin dilaurate and triphenyl phosphite in a mass ratio of 1:2, and the amount of the anti-thermal decomposition auxiliary agent added is 2wt% of the polyester waste;

[0087] S3. The fibers melt-spun in step S2 are cooled and formed, and then immersed in an oil tank for 1.5 hours for oiling. The polyester oil in the oil tank is prepared by mixing 35 kg of polydimethylsiloxane, 12 kg of hexadecyltrimethylammonium chloride, 15 kg of polyvinyl alcohol, and 35 kg of octadecylamine polyoxyethylene ether. The amount of polyester oil used is 0.6 wt% of the cooled and formed fibers (i.e., 0.6 kg of polyester oil is used per 100 kg of fibers).

[0088] Then the fibers are wound, bundled, drawn, crimped and cut in sequence to produce regenerated fibers.

[0089] Example 2

[0090] A method for regenerating polyester waste yarn comprises the following steps:

[0091] S1. Washing, drying, and crushing polyester waste to obtain polyester waste;

[0092] S2. Using 1 kg of polyester waste as the treatment basis, the polyester waste was mixed with the modified polyacrylonitrile fiber prepared in Preparation Example 2 at a mass ratio of 1:0.2, and the mixture was put into a reactor. The temperature was raised to 300° C., and then a tackifier and an anti-thermal decomposition aid were added and mixed. The mixture was stirred at 300° C. for 2 h to melt, and then the molten polyester material was extruded through a spinneret for spinning;

[0093] Among them, the tackifier is 1,4-butanediol diglycidyl ether, and the addition amount of the tackifier is 0.1wt% of the polyester waste; the anti-thermal decomposition auxiliary agent is di-n-butyltin dilaurate and triphenyl phosphite with a mass ratio of 1:1.8, and the addition amount of the anti-thermal decomposition auxiliary agent is 1wt% of the polyester waste;

[0094] S3, cooling the melt-spun fibers from step S2 into shape and then soaking them in an oil tank for 1 hour for oiling. The polyester oil in the oil tank is prepared by mixing 30 kg of polydimethylsiloxane, 8 kg of hexadecyltrimethylammonium chloride, 10 kg of polyvinyl alcohol, and 30 kg of octadecylamine polyoxyethylene ether. The amount of polyester oil used is 0.6 wt% of the cooled and formed fibers (i.e., 0.6 kg of polyester oil is used per 100 kg of fibers).

[0095] Then the fibers are wound, bundled, drawn, crimped and cut in sequence to produce regenerated fibers.

[0096] Example 3

[0097] A method for regenerating polyester waste yarn comprises the following steps:

[0098] S1. Washing, drying, and crushing polyester waste to obtain polyester waste;

[0099] S2. Using 1 kg of polyester waste as the treatment basis, the polyester waste was mixed with the modified polyacrylonitrile fiber prepared in Preparation Example 3 at a mass ratio of 1:0.5, and the mixture was put into a reactor. The temperature was raised to 330° C., and then a tackifier and an anti-thermal decomposition aid were added and mixed. The mixture was stirred at 330° C. for 1.5 hours to melt, and then the molten polyester material was extruded through a spinneret for spinning;

[0100] Among them, the tackifier is 1,4-butanediol diglycidyl ether, and the addition amount of the tackifier is 0.5wt% of the polyester waste; the anti-thermal decomposition auxiliary agent is di-n-butyltin dilaurate and triphenyl phosphite with a mass ratio of 1:2.2, and the addition amount of the anti-thermal decomposition auxiliary agent is 3wt% of the polyester waste;

[0101] S3, cooling the melt-spun fibers from step S2 into shape and then soaking them in an oil tank for 2 hours for oiling. The polyester oil in the oil tank is prepared by mixing 40 kg of polydimethylsiloxane, 15 kg of hexadecyltrimethylammonium chloride, 20 kg of polyvinyl alcohol, and 40 kg of octadecylamine polyoxyethylene ether. The amount of polyester oil used is 0.7 wt% of the cooled and formed fibers (i.e., 0.7 kg of polyester oil is used per 100 kg of fibers).

[0102] Then the fibers are wound, bundled, drawn, crimped and cut in sequence to produce regenerated fibers.

[0103] Example 4

[0104] A method for regenerating polyester waste yarn is carried out according to the method in Example 1, except that the modified polyacrylonitrile fiber in step S2 is the modified polyacrylonitrile fiber prepared in Preparation Example 4.

[0105] Example 5

[0106] A method for regenerating polyester waste yarn is carried out according to the method in Example 1, except that in step S2, di-n-butyltin dilaurate is used as an anti-thermal decomposition auxiliary agent.

[0107] Example 6

[0108] A polyester waste regeneration method is carried out according to the method in Example 1, except that the amount of tackifier added in step S2 is 1 wt% of the polyester waste.

[0109] Comparative Example 1-2

[0110] A method for regenerating polyester waste yarn is carried out according to the method in Example 1, except that the modified polyacrylonitrile fiber in step S2 is the modified polyacrylonitrile fiber in Comparative Preparation Example 1 and Comparative Preparation Example 2, respectively.

[0111] Comparative Example 3

[0112] A method for regenerating polyester waste yarn is carried out according to the method in Example 1, except that no modified polyacrylonitrile fiber is added in step S2.

[0113] Comparative Example 4

[0114] A method for regenerating polyester waste is carried out according to the method in Example 1, except that no modified polyacrylonitrile fiber is added in step S2, and the amount of thickener added is 1 wt% of the polyester waste.

[0115] Comparative Example 5

[0116] A method for regenerating polyester waste yarn is carried out according to the method in Example 1, except that in step S2, the modified polyacrylonitrile fiber is replaced by polyacrylonitrile fiber in equal amounts.

[0117] Comparative Example 6

[0118] A method for regenerating polyester waste yarn is carried out according to the method in Example 1, except that no anti-thermal decomposition auxiliary agent is added in step S2.

[0119] Performance testing

[0120] The spinning conditions during the regeneration process of the above-mentioned embodiments and comparative examples were statistically analyzed. In addition, the mechanical properties of the regenerated fibers produced in the above-mentioned embodiments and comparative examples were tested with reference to GB / T 14337-2008 "Determination of breaking strength and breaking elongation of chemical fibers". The test results are shown in Table 1 below.

[0121] Table 1:

[0122]

[0123] Referring to the test results in Table 1 above, the regenerated fibers obtained in Examples 1-3 of the present application have high breaking strength, and no problems such as broken ends and hairy fibers occur during the production process. Referring to the test results of Examples 1 and 4, the aminopyridine in the modified polyacrylonitrile fiber in Example 4 is monoaminopyridine, and it can be seen that the strength is reduced; referring to Example 5, when the anti-thermal decomposition auxiliary agent is only added with di-n-butyltin dilaurate and no triphenyl phosphite is added, its strength is also significantly reduced. Triphenyl phosphite also acts as a catalyst to achieve the addition of the thickener and polyester, and also plays a cross-linking role in the cross-linking of the modified polyacrylonitrile fiber and polyester, forming a macromolecular network structure, and improving the mechanical properties of the regenerated fiber; referring to the test results of Example 6, when the amount of thickener added in Example 6 is large, its mechanical properties are not improved, and the viscosity of the molten material is large during the waste silk regeneration process, and it is difficult to flow during the spinning process, the efficiency is reduced, and it can be clearly observed that the surface of the obtained fiber is not smooth and flat, and the quality is reduced.

[0124] Referring to the test results of Example 1 and Comparative Examples 1 and 2, it can be seen that when the modified polyacrylonitrile fiber is modified by only porous carbon powder or only aminopyridine, the strength of the regenerated fiber is significantly reduced; referring to the test results in Comparative Example 3, when the modified polyacrylonitrile fiber is not added, the strength is significantly reduced, and a large number of fiber breakages and fuzziness occur during production due to the low viscosity. Combined with the test results of Comparative Example 4, when the modified polyacrylonitrile fiber is not added and the amount of thickener added is increased, it can be seen that the strength and mechanical properties of the regenerated fiber are reduced, and a small amount of breakage and fuzziness occur during the regeneration process, but it is slightly improved compared to Example 3; referring to the test results of Comparative Example 5, the modified polyacrylonitrile fiber is not added. When the polyacrylonitrile fiber is replaced by polyacrylonitrile fiber in equal amounts, the strength of the regenerated fiber is improved compared with that of Comparative Examples 3 and 4, but it is still far lower than that of Example 1, and more broken ends and fuzzy fibers occur during the regeneration of the waste silk. The broken ends and fuzzy fibers are more serious than those of Comparative Example 4, and are improved compared with Comparative Example 3. Although the thickener can make up for the viscosity loss during the melting process, the final strength and mechanical properties are still poor, and adding too much will also cause extrusion difficulties. In this application, partially modified polyacrylonitrile fiber is used to make up for the strength and viscosity, and the final regenerated fiber has better mechanical properties and can meet high-strength requirements. When no anti-thermal decomposition additive is added in Comparative Example 6, its mechanical properties are poor, and slight broken ends and fuzzy fibers also occur.

[0125] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for regenerating polyester waste yarn, characterized in that: The following steps are involved: S1. Washing, drying, and crushing polyester waste to obtain polyester waste; S2, mixing polyester waste and modified polyacrylonitrile fiber in a mass ratio of 1: (0.2-0.5), then adding a tackifier and an anti-thermal decomposition additive, mixing, and melt spinning; S3, cooling and oiling, winding and bundling, drawing, crimping and cutting to obtain regenerated fiber; Wherein, in step S2, the modified polyacrylonitrile fiber is prepared by immersing the polyacrylonitrile fiber in a modifying solution and then heat-treating it. The modifying solution is prepared by mixing a cross-linking agent, aminopyridine-modified porous carbon powder and a solvent.

2. The method for regenerating polyester waste according to claim 1, wherein: The aminopyridine-modified porous carbon powder is prepared by the following method: 1) The coffee grounds are cleaned, dried, crushed and ground to obtain coffee powder, which is then immersed in a nitric acid solution and then carbonized at high temperature under an inert gas atmosphere. The porous carbon powder is then screened, crushed, washed and dried. 2) The porous carbon powder prepared in step 1) is immersed in a solution containing aminopyridine for reaction, and then filtered, washed and dried to obtain aminopyridine-modified porous carbon powder.

3. The method for regenerating polyester waste according to claim 2, wherein: When preparing aminopyridine-modified porous carbon powder, the aminopyridine in step 2) is selected from one or both of 2,6-diaminopyridine and 3,5-diaminopyridine.

4. The method for regenerating polyester waste according to claim 2, wherein: When preparing aminopyridine-modified porous carbon powder, the carbonization temperature in step 1) is 720-800° C. and the carbonization time is 2-4 hours.

5. The method for regenerating polyester waste according to claim 2, wherein: When preparing aminopyridine-modified porous carbon powder, the aminopyridine-containing solution in step 2) is prepared by mixing aminopyridine and water in a mass ratio of 1:(6-8), and the porous carbon powder and the aminopyridine-containing solution are added in a mass ratio of 1:(5-6).

6. The method for regenerating polyester waste according to claim 2, wherein: When preparing aminopyridine-modified porous carbon powder, the immersion temperature in step 2) is 35-45° C. and the immersion time is 2-3 h.

7. The method for regenerating polyester waste according to claim 1, wherein: Modacrylic fiber is produced by the following method: A cross-linking agent is mixed with dimethylformamide, and then aminopyridine-modified porous carbon powder is added to obtain a modified solution. Then, polyacrylonitrile fiber is added to the modified solution, immersed at 65-70°C for 1-2 hours, heat-treated at 80-100°C for 2-3 hours, and then washed and dried to obtain modified polyacrylonitrile fiber. The cross-linking agent is glutaraldehyde and organic peroxide in a mass ratio of 1: (1.5-2); The amount of cross-linking agent added is 3-5wt% of the amount of polyacrylonitrile fiber added, the amount of aminopyridine modified porous carbon powder added is 15-20wt% of the amount of polyacrylonitrile fiber added, and the amount of dimethylformamide added is 6-8 times the mass of the amount of polyacrylonitrile fiber added.

8. The method for regenerating polyester waste according to claim 1, wherein: In step S2, 1,4-butanediol diglycidyl ether is selected as the tackifier, and the amount of the tackifier added is 0.1-0.5 wt % of the polyester waste.

9. The method for regenerating polyester waste according to claim 1, wherein: In step S2, the anti-thermal decomposition auxiliary agent is selected from di-n-butyltin dilaurate and triphenyl phosphite in a mass ratio of 1: (1.8-2.2), and the added amount of the anti-thermal decomposition auxiliary agent is 1-3wt% of the polyester waste.

10. Regenerated fiber prepared by the polyester waste regeneration method according to any one of claims 1 to 9.

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