CN116876105A - Method for preparing hydrophilic regenerated fibers by in-situ reaction by taking waste polyester-nylon fabrics as raw materials - Google Patents

Abstract

The invention discloses a method for preparing hydrophilic regenerated fibers by taking waste polyester-nylon fabrics as raw materials through in-situ reaction, wherein waste polyester foam materials are subjected to in-situ tackifying through a micro-alcoholysis-self-polycondensation process to obtain polyester regenerated particles; mixing the obtained polyester regenerated particles and nylon particles, and putting the mixture into a double-screw extruder for premixing to obtain regenerated polyester-nylon particles; putting the dried regenerated polyester-nylon particles into a melt spinning machine for traction to obtain regenerated polyester-nylon fibers; the linear density of the polyester-nylon regenerated fiber is 30-300 dtex, the breaking strength can reach 2.0-8.0 cN/dtex, the breaking elongation is 10.0-100.0%, and all mechanical properties reach the chemical fiber filament stretching standard. The contact angle of the regenerated polyester-nylon fiber is reduced from 91.2 degrees to 71+/-5 degrees according to the different addition amounts of nylon, and the hydrophilicity is obviously improved; according to the invention, the terylene regenerated particles and the chinlon particles are premixed in a double-screw extruder, and the terylene-chinlon regenerated fiber with good performance is obtained through traction, and the contact angle of the regenerated fiber is obviously reduced, so that hydrophilic modification of the regenerated terylene-chinlon fiber is realized.

Description

A method of preparing hydrophilic regenerated fibers by in-situ reaction using waste polyester and nylon fabrics as raw materials method

Technical field

The invention relates to the field of high-value utilization of waste textiles, and specifically relates to a method for preparing hydrophilic regenerated fibers by in-situ reaction using waste polyester fabrics as raw materials and blending with hydrophilic regenerated nylon particles.

Background technique

With the rapid development of society, people's living standards continue to improve, the demand for textiles continues to increase, and the output of fiber is also increasing. Among them, polyester is widely used in clothing fabrics, decorative materials and industrial fabrics because of its stable performance and good mechanical properties. As a hydrophobic fabric, pure polyester fabrics are not comfortable enough when used as clothing fabrics. It is often necessary to prepare polyester-cotton blended fabrics with certain hygroscopic properties by blending them with natural fibers with certain hygroscopic properties. Due to the special structure of the mixed fabric, the polyester and cotton components cannot be separated by simple sorting means. However, when polyester-cotton blended fabrics are melted and recycled, the structural differences between natural fibers and chemical fibers make it difficult to recycle such blended fabrics. On this basis, it is urgent to find a suitable way to hydrophilically modify polyester fabrics to improve its hydrophilic properties and facilitate subsequent recycling and reuse. The invention uses waste polyester fabrics and regenerated nylon particles as raw materials, and reacts in situ to prepare polyester and nylon regenerated fibers, thereby realizing high-value utilization of waste polyester textile waste. Compared with pure polyester fabrics, the presence of a small amount of regenerated nylon significantly improves the hydrophilic properties of regenerated fibers.

Scholars at home and abroad have also developed some methods to recycle polyester and nylon blended fabrics. Publication number CN110845723 A announced a method for depolymerizing waste polyester and adding nylon online to prepare copolyester amide. The patent uses waste polyester particles as raw materials , mixed with ethylene glycol for depolymerization to obtain a high-purity waste polyester depolymerization liquid. The depolymerization liquid and nylon are mixed and polycondensed to obtain polyester amide copolymer. This method uses a large amount of ethylene glycol solvent to completely depolymerize waste polyester foam and polyester bottle flakes under the action of a catalyst to obtain a depolymerization solution, which is then mixed with nylon and polycondensed multiple times at different temperatures to obtain a polyester amide copolymer. This process consumes high energy and has a long reaction cycle. Publication No. CN 109535478 A discloses a recycling method for PA6 copolymer-modified PET polyester waste. This patent utilizes the different solubilities of polyamide alcoholysis products and bishydroxyethyl terephthalate at low temperatures to crystallize and precipitate high-purity crude bishydroxyethyl terephthalate, which can be directly used to prepare unsaturated polyesters and coatings. This method uses a large amount of ethylene glycol and zinc acetate catalyst to crystallize PA6 modified copolyester waste particles at low temperature to precipitate crude BHET for powder coatings, without reusing it for the production of new fibers.

On this basis, the present invention uses waste polyester fabric as raw material, and uses the "micro-alcohololysis-self-condensation polymerization" process to improve the quality and increase the viscosity to obtain polyester recycled particles, so that the intrinsic viscosity is significantly improved and can reach the spinning standard. And by adding a small amount of regenerated nylon particles during the spinning process, the hydrophilic properties of polyester and nylon regenerated fibers are significantly improved compared to pure polyester fabrics.

Contents of the invention

The first purpose of the present invention is to provide a high-value recycling method for waste polyester fabrics in view of the increasing amount of textile waste and low recycling rate, resulting in great waste of energy; the second purpose is to address the large amount of polyester-cotton hydrophilic fabrics that exist It is a difficult problem in recycling. A method for hydrophilic modification of polyester fabrics that improves hydrophilic properties and facilitates subsequent recycling is provided. In this method, waste polyester fabrics are first put into a grinding disc granulator and subjected to densification treatment to obtain waste polyester foam; after the waste polyester foam is evenly mixed with a certain amount of glycol alcoholysis agent, it is put into a twin-screw extruder at a certain temperature. Alcoholysis extrusion under temperature and shear conditions, and then the alcoholysis pellets and catalyst are mixed and put into a high-temperature and high-pressure reactor, so that the alcoholysis sample is polycondensed in the melt state, significantly increasing the molecular weight and intrinsic viscosity of the recycled polyester. Compared with polyester, nylon has better hydrophilic properties, and the hydrophilic properties of the blended fiber can be improved by blending with nylon. During the blending process, polyester and nylon are prone to ester-amide exchange reactions, resulting in self-compatible block copolymers that significantly improve the mechanical properties of the blended regenerated fibers. Since polyester and nylon melts are prone to degradation under conditions such as high temperature and shearing, the premixing of polyester and nylon needs to be carried out at a lower temperature to reduce degradation caused by high temperatures. Finally, the premixed regenerated polyester and nylon particles are put into a spinning machine and pulled into filaments to obtain hydrophilic polyester and nylon regenerated fibers with certain mechanical properties. This method provides an efficient and high-value recycling method and a hydrophilic modification method for the recycling of polyester fabrics.

Specifically, the first object of the present invention is to provide a method for obtaining polyester and nylon regenerated fibers by blending waste polyester fabrics as raw materials with regenerated nylon. The physical and mechanical properties of the regenerated fibers meet the fiber usage standards (GB/T14344- 2008).

The second object of the present invention is to provide a method for preparing hydrophilic regenerated fiber by in-situ reaction of waste polyester fabric as raw material and blended with nylon. The small amount of nylon present in the raw material of this method can significantly improve the regenerated fiber after in-situ compatibilization. hydrophilic properties.

The object of the present invention is achieved in this way, a method for preparing hydrophilic regenerated fibers by in-situ reaction using waste polyester and nylon fabrics as raw materials, the steps include:

Step 1: The collected waste polyester fabric is granulated with a grinding disc to obtain waste polyester foam, which is then improved in quality and viscosity through a "micro-alcohololysis-self-polycondensation" process to obtain polyester recycled particles with significantly improved intrinsic viscosity;

Step 2: Simply dry and mix the polyester recycled particles and recycled nylon particles obtained in step one, put them into a twin-screw extruder, and premix them under a certain plasticizing temperature and shearing conditions to obtain polyester and nylon recycled particles;

Step 3: After drying the polyester and nylon regenerated particles obtained in step 2, put them into a melt spinning machine and pull them into filaments at a certain temperature, host screw speed, and traction speed to obtain polyester and nylon regenerated fibers.

In the "micro alcoholysis-autocondensation polymerization" process conditions described in the above step one, the amount of ethylene glycol alcoholysis agent used is 0.5 to 10 phr based on the mass of the waste polyester fabric. The catalyst in the autocondensation polymerization process is an antimony-based catalyst. The addition amount is 50~500ppm, the polycondensation temperature in the high-temperature and high-pressure reactor is 230~280°C, the polycondensation time is 1-4h, the polycondensation vacuum degree is ≤0.02Mpa, and the intrinsic viscosity of the polyester recycled particles is 0.6~1.0 dL/g.

The moisture content of the dried polyester nylon regenerated particles described in step two above is required to be ≤50ppm; in the twin-screw extruder premixing process conditions described in step two, the host screw speed is 100~500 rpm, and the twin-screw extruder The temperature in zone 1 to zone 10 of the machine feed inlet is 50~300 ℃.

In the process conditions of the melt spinning machine described in the above step three, the temperature of the screw main engine of the melt spinning machine is 100~280°C, the main screw speed is 10~50 rpm, the heat drawing temperature is 60~120°C, and the traction The speed is 1.0~5.0.

The linear density of the polyester and nylon regenerated fiber obtained in the above step three is 20~300 dtex, the breaking strength is 2.0~6.0cN/dtex, and the breaking elongation is 10.0~100.0%; the contact angle of the polyester and nylon regenerated fiber is reduced to 71±5 °

Specifically, in order to achieve the purpose of the present invention, the present invention adopts the following technical solutions:

As mentioned above, the specific steps of a method for preparing hydrophilic regenerated fibers by in-situ reaction using waste polyester fabrics as raw materials are:

(1) Mix the waste polyester foam and 0.2~10 phr glycol alcoholysis agent evenly, then put it into a twin-screw extruder for alcoholysis extrusion. After alcoholysis, the melt is mixed with 100~300 ppm antimony catalyst and put into a high-temperature and high-pressure reactor, and polycondensed at a temperature of 230~280°C for 1-4 hours. The polycondensation vacuum degree is ≤0.02Mpa. The intrinsic viscosity of the obtained polyester recycled particles is 0.6~1.0dL/g. It is necessary to control the intrinsic viscosity of polyester recycled particles after polycondensation by controlling the amount of alcoholysis agent and conditions such as polycondensation temperature, vacuum degree, and polycondensation time;

(2) Dry the polyester obtained in step (1) in a blast drying oven at 110±20°C for more than 10 hours, and vacuum-dry the recycled nylon particles at 100±20°C for more than 10 hours until the moisture content is lower than 50 ppm. ;

(3) Preliminarily mix the dried polyester recycled particles and recycled nylon particles in step (2) and then put them into a twin-screw extruder for premixing. The main screw temperature of the twin-screw extruder is 50~300°C and the main screw speed is It is 100~500rpm to obtain polyester regenerated particles. In order to enable the small amount of recycled nylon particles to be well dispersed in the polyester melt, premixing is required in the twin-screw. However, it should be noted that polyester is prone to degradation under conditions such as high temperature and shearing. The melt is required to be blended and plasticized at a lower temperature to reduce the degradation of polyester caused by high temperature conditions. In addition, the twin-screw premixing process is required to initially carry out the ester-amide exchange reaction of the polyester and nylon melts to ensure the stability of the regenerated fiber in the subsequent spinning process.

(4) Drum dry the polyester regenerated particles obtained in step (3) so that the moisture content is less than 50ppm;

The dried polyester and nylon regenerated particles obtained in step (4) are put into a melt spinning machine for melt draft spinning. Among them, the main machine screw temperature is 100~280℃, the main machine screw speed is 10~50rpm, the heat drawing temperature is 60~120℃, and the traction speed is 1.0~5.0. The linear density of polyester and nylon regenerated fiber is 20~300 dtex, the breaking strength can reach 2.0~8.0 cN/dtex, the elongation at break is 10.0~100.0%, and the contact angle of regenerated polyester and nylon fiber is ≤80°. It is necessary to control the linear density of polyester and nylon regenerated fibers by controlling the drafting speed during the melt spinning process.

As the preferred technical solution:

A method of preparing hydrophilic regenerated fibers by in-situ reaction using waste polyester fabrics as raw materials. The intrinsic viscosity of the polyester regenerated particles after thickening through the "micro-alcohololysis-autocondensation polymerization" process can be stabilized at 0.6~1.0dL/g. Preferably 0.6-0.8dL/g, linear density of polyester and nylon regenerated fiber is 20~300 dtex, preferably 50~200 dtex, breaking strength is 2.0~8.0 cN/dtex, preferably 3.0~5.0 cN/dtex, and elongation at break is 10.0~ 100.0%, preferably 10.0~30.0% (according to national standard GB/T 14344-2008).

The beneficial effects of the present invention are: providing a method for preparing hydrophilic regenerated fibers using waste polyester fabrics. The linear density of the prepared regenerated fibers is 20 to 300 dtex, the breaking strength can reach 2.0 to 8.0 cN/dtex, and the elongation at break 10.0~100.0%. The method of the present invention uses waste polyester fabrics as raw materials, and uses a "micro-alcohololysis-self-condensation polymerization" viscosity-increasing process to improve the quality and viscosity of waste polyester fabrics to obtain polyester regenerated particles with significantly increased molecular weight and intrinsic viscosity. By blending and plasticizing nylon particles with higher hydrophilic properties, the hydrophilic properties of the regenerated fibers are improved, and the wearing comfort of clothes made from the regenerated fibers is improved.

Description of the drawings

Figure 1 shows the DSC cooling and heating curves of polyester and nylon regenerated fibers obtained in Example 1 of the present invention.

Figure 2 shows the water contact angles of pure polyester fabric (left) and polyester/nylon regenerated fiber (right) in Example 1.

Figure 3 shows the water contact angles of pure polyester fabric (left) and polyester/nylon regenerated fiber (right) in Example 2.

Figure 4 shows the water contact angles of pure polyester fabric (left) and polyester/nylon regenerated fiber (right) in Example 3.

Detailed ways

The waste polyester fabrics and recycled nylon particles used in the following examples of the present invention (purchased from Fujian Baichuan Resources Recycling Technology Co., Ltd.). The present invention will be further described below in conjunction with specific embodiments. It should be understood that the following examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

Example 1

A method for preparing hydrophilic regenerated fibers using waste polyester fabrics as raw materials through in-situ reaction. The steps are as follows:

(1) Preliminarily mix the waste polyester foam with 1.2phr (phr is the abbreviation of Parts per hundred parts of resin, which represents the amount of ethylene glycol added per 100 parts of waste polyester foam) and put it in Alcoholysis and extrusion are performed in a twin-screw extruder. The resulting alcoholysis particles are mixed with 200 ppm catalyst antimony glycol and then enter the high-temperature and high-pressure reactor for polycondensation. Control the polycondensation temperature at 270±5°C, the vacuum degree in the kettle ≤0.03 Mpa, the stirring paddle speed in the kettle 750rpm, and the polycondensation time 3 h to obtain polyester recycled particles with an intrinsic viscosity stable at 0.73±0.02dL/g.

(2) Preliminarily mix the polyester recycled particles obtained in step (1) and 6wt% recycled nylon particles, then put them into a twin-screw extruder for premixing to obtain polyester and nylon recycled particles.

(3) Put the polyester and nylon regenerated particles in step (2) into the melt spinning machine, control the screw plasticizing temperature to 230~280°C, and control the drafting ratio to 3.0 to obtain polyester and nylon regeneration with a linear density of 115±3 dtex. fiber.

In the above step (1), the waste polyester foam needs to be dried in a blast drying oven at 100 ℃ ± 10 ℃ for more than 10 hours to make the moisture content less than 50 ppm. During the alcoholysis extrusion process, the main screw of the twin-screw extruder The temperature settings from the first zone of the feeding port to the tenth zone of the machine head are 120 ℃, 150 ℃, 170 ℃, 200 ℃, 228 ℃, 240 ℃, 250 ℃, 253 ℃, 255 ℃, 245 ℃; in step (2) The recycled nylon particles need to be dried in a vacuum drying oven for more than 10 hours under vacuum degree ≦ 0.01 Mpa and temperature (100 ℃ ± 10 ℃) to make the moisture content less than 50 ppm; melt spinning machine in step (3) The temperature settings of the main machine screw temperature from the feeding port to the machine head are 150 ℃, 220 ℃, 245 ℃, 260 ℃, 258 ℃, the hot drawing temperature is 85±2 ℃, and the main screw speed of the spinning machine is 40±10 rpm. .

According to the process conditions described in Example 1, three groups of polyester and nylon regenerated fibers were obtained, with sample numbers 1, 2, and 3.

Mechanical property test: Refer to GB/T 14344-2008 "Chemical Fibers - Test Method for Tensile Properties of Filament" to test the mechanical properties of polyester regenerated fiber. The tensile strength and elongation at break of regenerated fiber are shown in the table below;

.

Thermal performance test: The heating and cooling curves of polyester and nylon regenerated fibers are shown in Figure 1.

Hydrophilic performance test: The change diagram of water contact angle of pure polyester fabric (left) and polyester/nylon regenerated fiber (right) is shown in Figure 2.

Example 2

A method for preparing hydrophilic regenerated fibers using waste polyester fabrics as raw materials through in-situ reaction. The steps are as follows:

(1) Preliminarily mix the waste polyester foam with 1.1phr (phr is the abbreviation of Parts per hundred parts of resin, which represents the amount of ethylene glycol added per 100 parts of waste polyester foam) and put it in Alcoholysis and extrusion are performed in a twin-screw extruder. The resulting alcoholysis particles are mixed with 200 ppm catalyst antimony glycol and then enter the high-temperature and high-pressure reactor for polycondensation. Control the polycondensation temperature at 268±5°C, the vacuum degree in the kettle ≤0.02 Mpa, the stirring paddle speed in the kettle 750rpm, and the polycondensation time 3 h to obtain polyester recycled particles with an intrinsic viscosity stable at 0.75±0.02dL/g.

(2) Preliminarily mix the polyester recycled particles obtained in step (1) and 8wt% recycled nylon particles, then put them into a twin-screw extruder for premixing to obtain polyester and nylon recycled particles.

(3) Put the polyester and nylon regenerated particles in step (2) into the melt spinning machine, control the screw plasticizing temperature to 240~270°C, and control the draft ratio to 3.2 to obtain polyester and nylon regeneration with a linear density of 110±3 dtex. fiber.

In the above step (1), the waste polyester foam needs to be dried in a blast drying oven at 100 ℃ ± 10 ℃ for more than 10 hours to make the moisture content less than 50 ppm. During the alcoholysis extrusion process, the main screw of the twin-screw extruder The temperature settings from the first zone of the feeding port to the tenth zone of the machine head are 120 ℃, 150 ℃, 180 ℃, 210 ℃, 238 ℃, 252 ℃, 252 ℃, 253 ℃, 255 ℃, 248 ℃; in step (2) The recycled nylon particles need to be dried in a vacuum drying oven for more than 10 hours under vacuum degree ≦ 0.01 Mpa and temperature (100 ℃ ± 10 ℃) to make the moisture content less than 50 ppm; melt spinning machine in step (3) The temperature settings of the main machine screw temperature from the feeding port to the machine head are 170 ℃, 210 ℃, 245 ℃, 260 ℃, 258 ℃, the hot drawing temperature is 90±2 ℃, and the main screw speed of the spinning machine is 45±5 rpm. .

According to the process conditions described in Example 2, three groups of polyester and nylon regenerated fibers were obtained, with sample numbers 1, 2, and 3.

Mechanical property test: Refer to GB/T 14344-2008 "Chemical Fibers - Test Method for Tensile Properties of Filament" to test the mechanical properties of polyester regenerated fiber. The tensile strength and elongation at break of regenerated fiber are shown in the table below;

.

Hydrophilic performance test: The change diagram of water contact angle of pure polyester fabric (left) and polyester/nylon regenerated fiber (right) is shown in Figure 3.

Example 3

A method for preparing hydrophilic regenerated fibers using waste polyester fabrics as raw materials through in-situ reaction. The steps are as follows:

(1) Preliminarily mix the waste polyester foam with 0.8phr (phr is the abbreviation of Parts per hundred parts of resin, which represents the amount of triethylene glycol added per 100 parts of waste polyester foam) and then put it in After alcoholysis extrusion in a twin-screw extruder, the resulting alcoholysis particles are mixed with 215 ppm catalyst antimony glycol and then entered into a high-temperature and high-pressure reactor for polycondensation. Control the polycondensation temperature at 265±4°C, the vacuum degree in the kettle ≤0.02 Mpa, the stirring paddle speed in the kettle 700rpm, and the polycondensation time 3 h to obtain polyester recycled particles with an intrinsic viscosity stable at 0.71±0.02dL/g.

(2) Preliminarily mix the polyester recycled particles obtained in step (1) and 5.0wt% recycled nylon particles, then put them into a twin-screw extruder for premixing to obtain polyester and nylon recycled particles.

(3) Put the polyester and nylon regenerated particles in step (2) into the melt spinning machine, control the screw plasticizing temperature to 240~270°C, and control the drafting ratio to 3.3 to obtain polyester and nylon regeneration with a linear density of 110±3 dtex. fiber.

In the above step (1), the waste polyester foam needs to be dried in a blast drying oven at 100 ℃ ± 10 ℃ for more than 10 hours to make the moisture content less than 50 ppm. During the alcoholysis extrusion process, the main screw of the twin-screw extruder The temperature settings from the first zone of the feeding port to the tenth zone of the machine head are 120 ℃, 150 ℃, 170 ℃, 190 ℃, 218 ℃, 240 ℃, 253 ℃, 253 ℃, 255 ℃, 245 ℃; in step (2) The recycled nylon particles need to be dried in a vacuum drying oven for more than 10 hours under vacuum degree ≦ 0.01 Mpa and temperature (100 ℃ ± 10 ℃) to make the moisture content less than 50 ppm; melt spinning machine in step (3) The temperature settings of the main machine screw temperature from the feeding port to the machine head are 180 ℃, 220 ℃, 245 ℃, 262 ℃, 260 ℃, the hot drawing temperature is 90±2 ℃, and the main screw speed of the spinning machine is 45±5 rpm. .

According to the process conditions described in Example 3, three groups of polyester and nylon regenerated fibers were obtained, with sample numbers 1, 2, and 3.

Mechanical property test: Refer to GB/T 14344-2008 "Chemical Fibers - Test Method for Tensile Properties of Filament" to test the mechanical properties of polyester regenerated fiber. The tensile strength and elongation at break of regenerated fiber are shown in the table below;

.

Hydrophilic performance test: The change diagram of water contact angle of pure polyester fabric (left) and polyester-nylon regenerated fiber (right) is shown in Figure 4.

Claims (5)

1. A method for preparing hydrophilic regenerated fibers by in-situ reaction using waste polyester and nylon fabrics as raw materials. The steps include: Step 1: The collected waste polyester fabric is granulated with a grinding disc to obtain waste polyester foam, which is then improved in quality and viscosity through a "micro-alcohololysis-self-polycondensation" process to obtain polyester recycled particles with significantly improved intrinsic viscosity; Step 2: Simply dry and mix the polyester recycled particles and recycled nylon particles obtained in step one, put them into a twin-screw extruder, and premix them under a certain plasticizing temperature and shearing conditions to obtain polyester and nylon recycled particles; Step 3: After drying the polyester and nylon regenerated particles obtained in step 2, put them into a melt spinning machine and pull them into filaments at a certain temperature, host screw speed, and traction speed to obtain polyester and nylon regenerated fibers. 2. A method for preparing hydrophilic regenerated fibers by in-situ reaction using waste polyester and nylon fabrics as raw materials according to claim 1, characterized in that in the "slight alcoholysis-self-polycondensation" process conditions described in step one, The added amount of glycol glycolysis agent used is 0.5~10 phr based on the mass of waste polyester fabric. The catalyst in the self-condensation polymerization process is an antimony catalyst with an added amount of 50~500 ppm. The polycondensation temperature in the high-temperature and high-pressure reactor is 230°C. ~280 ℃, the polycondensation time is 1-4h, the polycondensation vacuum degree is ≤0.02 Mpa, and the intrinsic viscosity of polyester recycled particles is 0.6~1.0 dL/g. 3. A method for preparing hydrophilic regenerated fibers by in-situ reaction using waste polyester and brocade fabrics as raw materials according to claim 1, characterized in that the moisture content of the polyester and brocade regenerated particles after drying described in step two is required to be ≤ 50ppm; in the twin-screw extruder premixing process conditions described in step 2, the host screw speed is 100~500 rpm, and the temperature of the twin-screw extruder inlet zone 1 to zone 10 is 50~300 ℃. 4. A method for preparing hydrophilic regenerated fibers by in-situ reaction using waste polyester fabric as raw material according to claim 1, characterized in that, in the process conditions of the melt spinning machine described in step three, melt spinning The temperature of the screw main engine of the machine is 100~280 ℃, the main screw speed is 10~50 rpm, the heat drawing temperature is 60~120 ℃, and the traction speed is 1.0~5.0. 5. A method for preparing hydrophilic regenerated fibers using waste polyester fabrics as raw materials through in-situ reaction according to claim 1, characterized in that the linear density of the polyester and nylon regenerated fibers obtained in step three is 20 to 300 dtex, and the linear density is 20 to 300 dtex. The strength is 2.0~6.0cN/dtex, the elongation at break is 10.0~100.0%; the contact angle of polyester and nylon regenerated fiber is reduced to 71±5°.