CN118792752A - A method for recycling waste polyester to prepare skin-friendly antibacterial fiber - Google Patents

Abstract

The invention discloses a method for preparing skin-friendly antibacterial fiber by recycling and regenerating waste polyester, and relates to the field of fiber. When preparing skin-friendly antibacterial fiber, the present invention performs alcohol-alkali combined depolymerization on waste polyester fabric to obtain terephthalic acid; reacts trimethylphosphine and 7-bromoheptanal to obtain quaternary phosphonium salt; then reacts chitosan with quaternary phosphonium salt and propylene chloride in sequence to obtain modified chitosan; hydrolyzes and acidifies di-acid precursor monomer after reacting allylphosphine dichloride and ethyl para-aminobenzoate; finally, the recovered terephthalic acid, diacid precursor monomer and ethylene glycol are polymerized and mixed with modified chitosan for spinning, and then immersed in sodium hypochlorite solution to obtain skin-friendly antibacterial fiber. The skin-friendly antibacterial fiber prepared by the present invention has excellent flame retardant properties, antibacterial properties and water washability.

Description

A method for recycling waste polyester to prepare skin-friendly antibacterial fiber

Technical Field

The invention relates to the field of fibers, and in particular to a method for preparing skin-friendly and antibacterial fibers by recycling and regenerating waste polyester.

Background Art

The textile and light industry is closely related to human life. With the advancement of science and technology and economic development, the status of the textile industry has not decreased but increased, and its application areas have been continuously expanded. Modern people have a higher pursuit of life taste, which shortens the use cycle of textiles. Coupled with the rapid growth of population, the number of discarded textile products has increased year by year, but only less than 5% of them can be returned to the market. Most discarded textile products are disposed of or recycled by landfill or incineration. Incineration not only generates harmful and non-degradable substances that cause secondary pollution, but also wastes a lot of resources.

Polyester is the most widely used synthetic fiber due to its excellent physical properties, but it is also the most discarded fiber. It is currently mainly used in the fields of clothing and food packaging. On the one hand, it promotes economic development and optimizes people's daily lives; on the other hand, due to its excellent chemical stability, it can remain in nature for a long time, causing white pollution, ecological damage and other problems, leading to a series of social problems and having a negative impact on people's lives. Therefore, the present invention prepares a skin-friendly antibacterial fiber with excellent flame retardant properties, antibacterial properties and water washability.

Summary of the invention

The purpose of the present invention is to provide a method for recycling waste polyester to prepare skin-friendly antibacterial fibers, so as to solve the problems existing in the prior art.

In order to solve the above technical problems, the present invention provides the following technical solutions:

A method for preparing skin-friendly antibacterial fiber by recycling and regenerating waste polyester, characterized in that the skin-friendly antibacterial fiber is prepared by reacting recycled terephthalic acid, diacid precursor monomer, ethylene glycol and modified chitosan, spinning the reactants, and then soaking them in a sodium hypochlorite solution.

As an optimization, the terephthalic acid is obtained by alcohol-alkali combined depolymerization of waste polyester fabric.

As an optimization, the diacid precursor monomer is obtained by hydrolyzing and acidifying allyl phosphine dichloride and ethyl p-aminobenzoate.

As an optimization, the modified chitosan is obtained by first reacting trimethylphosphine with 7-bromoheptanal to obtain a quaternary phosphonium salt, and then reacting the chitosan with the quaternary phosphonium salt and allyl chloride in sequence.

A method for preparing skin-friendly antibacterial fiber by recycling waste polyester, comprising the following preparation steps:

(1) After the waste polyester fabric is crushed, it is washed with deionized water for 3 to 5 times, and dried at 75 to 85° C. for 3 to 4 hours to obtain polyester fragments; the polyester fragments, sodium bicarbonate, sodium hydroxide, ethylene glycol and titanium dioxide are mixed in a mass ratio of 1: (2.1 to 2.3): (1.4 to 1.6): (7 to 9): (0.01 to 0.03), stirred at 155 to 165° C. and 100 to 200 rpm for 0.5 to 1.5 hours under a nitrogen environment, cooled to 135 to 145° C., filtered, the filtrate is vacuum distilled at 170 to 180° C., dried at 65 to 75° C. for 3 to 4 hours, deionized water is added and stirred until dissolved, the pH is adjusted to 3 to 5 with a hydrochloric acid solution with a mass fraction of 36 to 38%, vacuum filtered, washed with deionized water for 3 to 5 times, and dried at 90 to 110° C. for 4 to 6 hours to obtain terephthalic acid;

(2) trimethylphosphine, acetone and sodium iodide are mixed in a mass ratio of 1:(2-3):(0.01-0.02), stirred at 100-300 rpm in a nitrogen atmosphere and heated to 35-45° C., 7-bromoheptanal (0.3-0.5 times the mass of trimethylphosphine) is added, stirred for 1.5-2.5 hours, filtered, washed with ethyl acetate 3-5 times, ventilated for 30-60 minutes, and dried at 35-45° C. for 5-7 hours to obtain a quaternary phosphine salt; Chitosan, glacial acetic acid and deionized water were mixed in a mass ratio of 1: (0.5-1.5): (20-22), and stirred at 20-30°C and 100-200rpm for 11-13h to obtain an aqueous solution; sorbitan oleate and liquid paraffin were mixed in a mass ratio of 1: (3.7-3.9), and stirred at 9000-11000rpm for 2-4min, and sorbitan oleate (mass 13.6-1 3.8 times of aqueous phase solution, stirring at 20-30°C and 100-200rpm for 2-4h, adding 1-2 times of quaternary phosphonium salt of sorbitan oleate at a uniform speed within 20-30, stirring at 35-45°C for 3-5h, cooling naturally to room temperature and centrifuging, washing with anhydrous ethanol and deionized water for 3-5 times respectively, drying at 55-65°C for 23-25h, and obtaining pre-modified chitosan; pre-modified chitosan, dimethyl sulfoxide and 3 mass fraction of oleic acid are added. 5-45% sodium hydroxide solution is mixed in a mass ratio of 1:(7-9):(18-22), stirred at 35-45°C and 150-250 rpm for 20-30 min, 2-3 times the mass of pre-modified chitosan propylene chloride is added at a uniform speed within 30-40 min, stirring is continued for 0.5-1.5 h and then centrifuged, washed alternately with anhydrous ethanol and deionized water for 3-5 times, and dried at 55-65°C for 12-14 h to obtain modified chitosan;

(3) Allyl phosphine dichloride, ethyl p-aminobenzoate and 1,4-dioxane are mixed in a mass ratio of 1:(4-4.1):(5-6), stirred at 84-86° C. and 200-300 rpm for 11-13 h under a nitrogen environment, and a mass fraction of 45-55% ethanol solution of 4-5 times the mass of allyl phosphine dichloride and a molar amount of sodium hydroxide of 2.1-2.3 times the molar amount of allyl phosphine dichloride are added, the temperature is lowered to 79-81° C. and stirring is continued for 2-4 h, a hydrochloric acid solution of pH 1.5-2.5 is added dropwise to adjust the solution pH to 2.5-3.5, and distilled under reduced pressure, washed 3-5 times with a hydrochloric acid solution of pH 1.5-2.5 and deionized water, respectively, and dried at 60-70° C. for 3-5 h, cooled to room temperature and filtered to obtain a diacid precursor monomer;

(4) the terephthalic acid, diacid precursor monomer, antimony trioxide and ethylene glycol obtained in step (1) are mixed in a mass ratio of 1: (0.4-0.6): (0.01-0.02): (0.6-0.8), stirred at 130-140° C., 0.01-0.03 MPa, and 100-200 rpm for 40-50 min in a nitrogen environment, heated to 175-185° C. and continued to stir for 1-2 h, then heated to 240-250° C., 80-90 Pa, and continued to stir until the viscosity remains unchanged to obtain a modified polyester; the modified polyester is heated at 215-225° C. Heat until melted, add modified chitosan in an amount of 0.2 to 0.3 times the mass of the modified polyester, stir at 200 to 300 rpm for 1 to 2 hours, add potassium persulfate in an amount of 0.01 to 0.03 times the mass of the modified polyester, continue stirring for 20 to 30 minutes, extrude and spin with a twin-screw extruder, stand at 70 to 80° C. for 6 to 8 hours after spinning, cool naturally to room temperature, and obtain spun fibers; soak the spun fibers in a sodium hypochlorite solution with a pH of 7 to 8 for 15 to 25 minutes, wash with deionized water for 3 to 5 times, and dry at 40 to 50° C. for 1 to 3 hours to obtain regenerated skin-friendly antibacterial fibers.

As an optimization, the reaction equation of the quaternary phosphonium salt in step (2) is:

As an optimization, the reaction equation of the pre-modified chitosan in step (2) is:

As an optimization, the reaction equation of the modified chitosan in step (2) is:

As an optimization, the reaction equation of the diacid precursor monomer in step (3) is:

Compared with the prior art, the beneficial effects achieved by the present invention are:

When preparing the skin-friendly antibacterial fiber, the present invention comprises the following steps: performing alcohol-alkali combined depolymerization on waste polyester fabric to obtain terephthalic acid; reacting trimethylphosphine with 7-bromoheptanal to obtain quaternary phosphonium salt; sequentially reacting chitosan with quaternary phosphonium salt and allyl chloride to obtain modified chitosan; reacting allylphosphine dichloride with ethyl p-aminobenzoate, hydrolyzing and acidifying to obtain a diacid precursor monomer; finally, polymerizing the recovered terephthalic acid, the diacid precursor monomer and ethylene glycol, mixing with the modified chitosan for spinning, and then soaking in a sodium hypochlorite solution to obtain the skin-friendly antibacterial fiber.

Firstly, waste polyester fabric is subjected to alcohol-alkali combined depolymerization to obtain terephthalic acid; trimethyl phosphine and 7-bromoheptanal are reacted to obtain quaternary phosphonium salt; chitosan is then reacted with quaternary phosphonium salt and allyl chloride in sequence to obtain modified chitosan; chitosan with good biocompatibility with human tissue is selected as a modified substance to give the skin-friendly antibacterial fiber a good skin-friendly effect, and a quaternary phosphonium salt structure is grafted onto chitosan, and the cationic part in the structure can interact with the negatively charged part in the cell membrane of microorganisms, destroy the cell membrane, and improve the antibacterial property of the skin-friendly antibacterial fiber; the introduced phosphorus element can effectively promote carbonization at high temperature, and improve the flame retardant property of the skin-friendly antibacterial fiber; at the same time, 7-bromoheptanal containing a hydrophobic carbon long chain is selected to synthesize quaternary phosphonium salt, and the water washing resistance of the skin-friendly antibacterial fiber is improved; allyl chloride is grafted onto chitosan, and a double bond structure that can be polymerized with the polyester main chain is introduced, so as to improve the binding force between the modified chitosan and the polyester main chain, and further improve the water washing resistance of the skin-friendly antibacterial fiber.

Secondly, allyl phosphine dichloride and ethyl p-aminobenzoate are reacted and then hydrolyzed and acidified to obtain a diacid precursor monomer; finally, the recovered terephthalic acid, the diacid precursor monomer and ethylene glycol are polymerized and mixed with modified chitosan for spinning, and then immersed in a sodium hypochlorite solution to obtain a skin-friendly antibacterial fiber; allyl phosphine dichloride is used to synthesize a diacid precursor monomer with a double bond, which is polymerized together with the recovered terephthalic acid, and a double bond structure and phosphorus element are introduced into the polyester main chain, and the double bond improves the binding force between the polyester main chain and the modified chitosan, thereby enhancing the water washability of the skin-friendly antibacterial fiber; the phosphorus element can react with the burning gas phase to generate oxidation products of phosphorus compounds, form a gas phase barrier layer, and improve the flame retardant properties of the skin-friendly antibacterial fiber; at the same time, a halamine precursor is introduced into the main chain, and a halamine structure is formed after being immersed in a sodium hypochlorite solution, which can destroy the cell membrane structure, interfere with the metabolism in the cell, and further improve the antibacterial properties of the skin-friendly antibacterial fiber.

DETAILED DESCRIPTION

The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

In order to more clearly illustrate the method provided by the present invention, the following examples are used to describe in detail the test methods for the various indicators of the skin-friendly antibacterial fibers prepared in the following examples:

Flame retardant properties: The skin-friendly antibacterial fibers obtained in the examples and the comparative examples were tested for limiting oxygen index (LOI ₀ ) according to GB/T5454.

Antibacterial performance: The skin-friendly antibacterial fibers obtained in each example and the comparative example were tested for the antibacterial rate (R ₀ ) against Escherichia coli according to the oscillation method in Part 3 of GB/T20944.

Washing resistance: The skin-friendly antibacterial fiber obtained in each embodiment and the comparative example were washed and dried with MD100V33WY, respectively, and the cycle was repeated 50 times; the limiting oxygen index (LOI ₁ ) was tested again according to GB/T5454, and the flame retardant performance retention rate (LOI ₁ /LOI ₀ *100%) was calculated; the antibacterial rate (R ₁ ) was tested again, and the antibacterial performance retention rate (R ₁ /R ₀ *100%) was calculated.

Example 1

A method for preparing skin-friendly antibacterial fiber by recycling waste polyester, the skin-friendly antibacterial fiber comprising the following preparation steps:

(1) After the waste polyester fabric is crushed, it is washed with deionized water for 3 times, and dried at 75° C. for 4 hours to obtain polyester fragments; the polyester fragments, sodium bicarbonate, sodium hydroxide, ethylene glycol and titanium dioxide are mixed in a mass ratio of 1:2.1:1.4:7:0.01, stirred at 155° C. and 100 rpm for 1.5 hours under a nitrogen environment, cooled to 135° C. and filtered, the filtrate is vacuum distilled at 170° C., dried at 65° C. for 4 hours, deionized water is added and stirred until dissolved, the pH is adjusted to 3 with a hydrochloric acid solution having a mass fraction of 36%, vacuum filtered, washed with deionized water for 3 times, and dried at 90° C. for 6 hours to obtain terephthalic acid;

(2) trimethylphosphine, acetone and sodium iodide were mixed in a mass ratio of 1:2:0.01, stirred at 100 rpm in a nitrogen atmosphere and heated to 35°C, 7-bromoheptanal (0.3 times the mass of trimethylphosphine) was added, stirring was continued for 2.5 hours, and then filtered, washed with ethyl acetate three times, ventilated for 30 minutes, and dried at 35°C for 7 hours to obtain a quaternary phosphine salt; chitosan, glacial acetic acid and deionized water were mixed in a mass ratio of 1:0.5:20, stirred at 20°C and 100 rpm for 13 hours to obtain an aqueous phase solution; sorbitan oleate and liquid paraffin were mixed in a mass ratio of 1:3.7, stirred at 9000 rpm for 4 minutes, and water (13.6 times the mass of sorbitan oleate) was added at a uniform rate within 10 minutes. The pre-modified chitosan was prepared by mixing the pre-modified chitosan, dimethyl sulfoxide and a sodium hydroxide solution with a mass fraction of 35% in a mass ratio of 1:7:18, stirring at 35°C and 150rpm for 30min, adding 2 times of allyl chloride in a mass ratio of 2 times of the pre-modified chitosan in a mass ratio of 1:7:18, stirring at 35°C and 150rpm for 30min, adding 2 times of allyl chloride in a mass ratio of 2 times of the pre-modified chitosan in a mass ratio of 1:7:18, stirring at 35°C and 150rpm for 30min, and centrifuging after stirring for 1.5h, washing with anhydrous ethanol and deionized water alternately for 3 times, and drying at 55°C for 14h to obtain the modified chitosan.

(3) Allyl phosphine dichloride, ethyl p-aminobenzoate and 1,4-dioxane were mixed in a mass ratio of 1:4:5, stirred at 84°C and 200 rpm for 13 h under a nitrogen environment, and a 45% ethanol solution of 4 times the mass of allyl phosphine dichloride and a sodium hydroxide solution of 2.1 times the molar amount of allyl phosphine dichloride were added, the temperature was lowered to 79°C and stirring was continued for 4 h, a hydrochloric acid solution of pH 1.5 was added dropwise to adjust the solution pH to 2.5, and the solution was distilled under reduced pressure, washed with a hydrochloric acid solution of pH 1.5 and deionized water for 3 times respectively, dried at 60°C for 5 h, cooled to room temperature and filtered to obtain a diacid precursor monomer;

(4) The terephthalic acid, diacid precursor monomer, antimony trioxide and ethylene glycol obtained in step (1) are mixed in a mass ratio of 1:0.4:0.01:0.6, stirred at 130°C, 0.01 MPa and 100 rpm for 50 min in a nitrogen environment, heated to 175°C and continued to stir for 2 h, then heated to 240°C and continued to stir at 80 Pa until the viscosity remains unchanged to obtain a modified polyester; the modified polyester is heated at 215°C until it is melted, 0.2 times the mass of the modified polyester is added with modified chitosan and stirred at 200 rpm for 2 h, then 0.01 times the mass of the modified polyester is added with potassium persulfate, and continued to stir for 30 min, and extruded and spun by a twin-screw extruder. After the spinning is completed, it is allowed to stand at 70°C for 8 h, and naturally cooled to room temperature to obtain a spun fiber; the spun fiber is immersed in a sodium hypochlorite solution with a pH of 7 for 25 min, washed with deionized water 3 times, and dried at 40°C for 3 h to obtain a regenerated skin-friendly antibacterial fiber.

Example 2

A method for preparing skin-friendly antibacterial fiber by recycling waste polyester, the skin-friendly antibacterial fiber comprising the following preparation steps:

(1) After the waste polyester fabric is crushed, it is washed with deionized water for 4 times, and dried at 80° C. for 3.5 hours to obtain polyester fragments; the polyester fragments, sodium bicarbonate, sodium hydroxide, ethylene glycol and titanium dioxide are mixed in a mass ratio of 1:2.2:1.5:8:0.02, stirred at 160° C. and 150 rpm for 1 hour under a nitrogen environment, cooled to 140° C. and filtered, the filtrate is vacuum distilled at 175° C., dried at 70° C. for 3.5 hours, deionized water is added and stirred until dissolved, the pH is adjusted to 4 with a hydrochloric acid solution with a mass fraction of 37%, vacuum filtered, washed with deionized water for 4 times, and dried at 100° C. for 5 hours to obtain terephthalic acid;

(2) Trimethylphosphine, acetone and sodium iodide were mixed in a mass ratio of 1:2.5:0.015, stirred at 200 rpm in a nitrogen atmosphere and heated to 40°C, 7-bromoheptanal (0.4 times the mass of trimethylphosphine) was added, the mixture was stirred for 2 hours, filtered, washed with ethyl acetate 4 times, ventilated for 45 minutes, and dried at 40°C for 6 hours to obtain a quaternary phosphine salt; chitosan, glacial acetic acid and deionized water were mixed in a mass ratio of 1:1:21, stirred at 25°C and 150 rpm for 12 hours to obtain an aqueous solution; sorbitan oleate and liquid paraffin were mixed in a mass ratio of 1:3.8, stirred at 10000 rpm for 3 minutes, and an aqueous solution (13.7 times the mass of sorbitan oleate) was added at a uniform rate within 15 minutes. The solution was stirred at 25°C and 150rpm for 3h, and a quaternary phosphonium salt with a mass of 1.5 times that of sorbitan oleate was uniformly added within 25, and the stirring was continued at 40°C for 4h. After natural cooling to room temperature, the mixture was centrifuged, washed with anhydrous ethanol and deionized water for 4 times respectively, and dried at 60°C for 24h to obtain pre-modified chitosan; the pre-modified chitosan, dimethyl sulfoxide and a sodium hydroxide solution with a mass fraction of 40% were mixed in a mass ratio of 1:8:20, and stirred at 40°C and 200rpm for 25min. Allyl chloride with a mass of 2.5 times that of the pre-modified chitosan was uniformly added within 35min, and the stirring was continued for 1h. After the mixture was centrifuged, the mixture was washed with anhydrous ethanol and deionized water alternately for 4 times, and dried at 60°C for 13h to obtain modified chitosan;

(3) Allyl phosphine dichloride, ethyl p-aminobenzoate and 1,4-dioxane were mixed in a mass ratio of 1:4.05:5.5, stirred at 85°C and 250rpm for 12h under a nitrogen environment, and a 50% ethanol solution with a mass fraction of 4.5 times the mass of allyl phosphine dichloride and sodium hydroxide with a molar amount of 2.2 times that of allyl phosphine dichloride were added, the temperature was cooled to 80°C and the stirring was continued for 3h, a hydrochloric acid solution with a pH of 2 was added dropwise to adjust the pH of the solution to 3, and the solution was distilled under reduced pressure, washed with a hydrochloric acid solution with a pH of 2 and deionized water for 4 times respectively, dried at 65°C for 4h, cooled to room temperature and filtered to obtain a diacid precursor monomer;

(4) the terephthalic acid, diacid precursor monomer, antimony trioxide and ethylene glycol obtained in step (1) are mixed in a mass ratio of 1:0.5:0.015:0.7, stirred at 135°C, 0.02MPa and 150rpm for 45min under a nitrogen environment, heated to 180°C and continued to stir for 1.5h, then heated to 245°C and continued to stir at 85Pa until the viscosity remains unchanged, to obtain a modified polyester; the modified polyester is heated at 220°C until it is melted, and the modified polyester is added The modified chitosan with a mass of 0.25 times that of the ester was stirred at 250 rpm for 1.5 h, and then potassium persulfate with a mass of 0.02 times that of the modified polyester was added and stirred for 25 min. The fibers were extruded and spun using a twin-screw extruder. After the spinning was completed, the fibers were allowed to stand at 75 ° C for 7 h and naturally cooled to room temperature to obtain spun fibers. The spun fibers were immersed in a sodium hypochlorite solution with a pH of 7.5 for 20 min, washed 4 times with deionized water, and dried at 45 ° C for 2 h to obtain regenerated skin-friendly antibacterial fibers.

Example 3

A method for preparing skin-friendly antibacterial fiber by recycling waste polyester, the skin-friendly antibacterial fiber comprising the following preparation steps:

(1) After the waste polyester fabric is crushed, it is washed with deionized water for 5 times, and dried at 85° C. for 3 h to obtain polyester fragments; the polyester fragments, sodium bicarbonate, sodium hydroxide, ethylene glycol and titanium dioxide are mixed in a mass ratio of 1:2.3:1.6:9:0.03, stirred at 165° C. and 200 rpm for 0.5 h under a nitrogen environment, cooled to 145° C. and filtered, the filtrate is vacuum distilled at 180° C., dried at 75° C. for 3 h, deionized water is added and stirred until dissolved, the pH is adjusted to 5 with a hydrochloric acid solution having a mass fraction of 38%, vacuum filtered, washed with deionized water for 5 times, and dried at 110° C. for 4 h to obtain terephthalic acid;

(2) trimethylphosphine, acetone and sodium iodide were mixed in a mass ratio of 1:3:0.02, stirred at 300 rpm in a nitrogen atmosphere and heated to 45°C, 7-bromoheptanal (0.5 times the mass of trimethylphosphine) was added, stirring was continued for 1.5 hours, and then filtered, washed with ethyl acetate 5 times, ventilated for 60 minutes, and dried at 45°C for 5 hours to obtain a quaternary phosphine salt; chitosan, glacial acetic acid and deionized water were mixed in a mass ratio of 1:1.5:22, stirred at 30°C and 200 rpm for 11 hours to obtain an aqueous phase solution; sorbitan oleate and liquid paraffin were mixed in a mass ratio of 1:3.9, stirred at 11000 rpm for 2 minutes, and water (13.8 times the mass of sorbitan oleate) was added at a uniform rate within 20 minutes. The pre-modified chitosan was prepared by mixing the pre-modified chitosan, dimethyl sulfoxide and a sodium hydroxide solution with a mass fraction of 45% in a mass ratio of 1:9:22, stirring at 45°C and 250rpm for 20min, adding 3 times of the mass of propylene chloride to the pre-modified chitosan at a uniform speed within 40min, continuing to stir for 0.5h, centrifuging, washing with anhydrous ethanol and deionized water for 5 times, and drying at 65°C for 12h to obtain the modified chitosan.

(3) Allyl phosphine dichloride, ethyl p-aminobenzoate and 1,4-dioxane were mixed in a mass ratio of 1:4.1:6, stirred at 86° C. and 300 rpm for 11 h under a nitrogen environment, and a mass fraction of 55% ethanol solution of 5 times the mass of allyl phosphine dichloride and a molar amount of sodium hydroxide of 2.3 times the molar amount of allyl phosphine dichloride were added, the temperature was cooled to 81° C. and stirring was continued for 2 h, a hydrochloric acid solution of pH 2.5 was added dropwise to adjust the solution pH to 3.5, and the solution was distilled under reduced pressure, washed 5 times with a hydrochloric acid solution of pH 2.5 and deionized water respectively, dried at 70° C. for 3 h, cooled to room temperature and filtered to obtain a diacid precursor monomer;

(4) The terephthalic acid, diacid precursor monomer, antimony trioxide and ethylene glycol obtained in step (1) were mixed in a mass ratio of 1:0.6:0.02:0.8, stirred at 140°C, 0.03 MPa and 200 rpm for 40 min in a nitrogen environment, heated to 185°C and continued to stir for 1 h, then heated to 250°C and continued to stir at 90 Pa until the viscosity remained unchanged, stirred at 130-140°C, 0.01-0.03 MPa and 100-200 rpm for 40-50 min in a nitrogen environment, heated to 175-185°C and continued to stir for 1-2 h, then heated to 240 The modified polyester was heated at 225°C and 80-90Pa until the viscosity remained unchanged to obtain a modified polyester; the modified polyester was heated at 225°C until it was melted, 0.3 times the mass of the modified polyester was added with modified chitosan and stirred at 300rpm for 1h, and then 0.03 times the mass of the modified polyester was added with potassium persulfate, and the stirring was continued for 20min, and the fibers were extruded and spun using a twin-screw extruder. After the spinning was completed, the fibers were allowed to stand at 80°C for 6h, and naturally cooled to room temperature to obtain spun fibers; the spun fibers were immersed in a sodium hypochlorite solution with a pH of 8 for 25min, washed with deionized water 5 times, and dried at 50°C for 1h to obtain regenerated skin-friendly and antibacterial fibers.

Comparative Example 1

A method for preparing skin-friendly antibacterial fiber by recycling waste polyester, the skin-friendly antibacterial fiber comprising the following preparation steps:

(1) After the waste polyester fabric is crushed, it is washed with deionized water for 4 times, and dried at 80° C. for 3.5 hours to obtain polyester fragments; the polyester fragments, sodium bicarbonate, sodium hydroxide, ethylene glycol and titanium dioxide are mixed in a mass ratio of 1:2.2:1.5:8:0.02, stirred at 160° C. and 150 rpm for 1 hour under a nitrogen environment, cooled to 140° C. and filtered, the filtrate is vacuum distilled at 175° C., dried at 70° C. for 3.5 hours, deionized water is added and stirred until dissolved, the pH is adjusted to 4 with a hydrochloric acid solution with a mass fraction of 37%, vacuum filtered, washed with deionized water for 4 times, and dried at 100° C. for 5 hours to obtain terephthalic acid;

(2) Trimethylphosphine, acetone and sodium iodide were mixed in a mass ratio of 1:2.5:0.015, stirred at 200 rpm in a nitrogen atmosphere and heated to 40°C, 7-bromoheptanal (0.4 times the mass of trimethylphosphine) was added, the mixture was stirred for 2 hours, filtered, washed with ethyl acetate 4 times, ventilated for 45 minutes, and dried at 40°C for 6 hours to obtain a quaternary phosphine salt; chitosan, glacial acetic acid and deionized water were mixed in a mass ratio of 1:1:21, stirred at 25°C and 150 rpm for 12 hours to obtain an aqueous solution; sorbitan oleate and liquid paraffin were mixed in a mass ratio of 1:3.8, stirred at 10000 rpm for 3 minutes, and an aqueous solution (13.7 times the mass of sorbitan oleate) was added at a uniform rate within 15 minutes. The solution was stirred at 25°C and 150rpm for 3h, and a quaternary phosphonium salt with a mass of 1.5 times that of sorbitan oleate was uniformly added within 25, and the stirring was continued at 40°C for 4h. After natural cooling to room temperature, the mixture was centrifuged, washed with anhydrous ethanol and deionized water for 4 times respectively, and dried at 60°C for 24h to obtain pre-modified chitosan; the pre-modified chitosan, dimethyl sulfoxide and a sodium hydroxide solution with a mass fraction of 40% were mixed in a mass ratio of 1:8:20, and stirred at 40°C and 200rpm for 25min. Allyl chloride with a mass of 2.5 times that of the pre-modified chitosan was uniformly added within 35min, and the stirring was continued for 1h. After the mixture was centrifuged, the mixture was washed with anhydrous ethanol and deionized water alternately for 4 times, and dried at 60°C for 13h to obtain modified chitosan;

(3) Allyl phosphine dichloride, ethyl p-aminobenzoate and 1,4-dioxane were mixed in a mass ratio of 1:4.05:5.5, stirred at 85°C and 250rpm for 12h under a nitrogen environment, and a 50% ethanol solution with a mass fraction of 4.5 times the mass of allyl phosphine dichloride and sodium hydroxide with a molar amount of 2.2 times that of allyl phosphine dichloride were added, the temperature was cooled to 80°C and the stirring was continued for 3h, a hydrochloric acid solution with a pH of 2 was added dropwise to adjust the pH of the solution to 3, and the solution was distilled under reduced pressure, washed with a hydrochloric acid solution with a pH of 2 and deionized water for 4 times respectively, dried at 65°C for 4h, cooled to room temperature and filtered to obtain a diacid precursor monomer;

(4) The terephthalic acid, diacid precursor monomer, antimony trioxide and ethylene glycol obtained in step (1) are mixed in a mass ratio of 1:0.5:0.015:0.7, stirred at 135°C, 0.02MPa and 150rpm for 45min in a nitrogen environment, heated to 180°C and continued to stir for 1.5h, then heated to 245°C and continued to stir at 85Pa until the viscosity remains unchanged to obtain a modified polyester; the modified polyester is heated at 220°C until it is melted, 0.25 times the mass of the modified polyester is added with modified chitosan, stirred at 250rpm for 1.5h, then 0.02 times the mass of the modified polyester is added with potassium persulfate, stirred for 25min, extruded and spun using a twin-screw extruder, and allowed to stand at 75°C for 7h after spinning, and naturally cooled to room temperature to obtain a regenerated skin-friendly antibacterial fiber.

Comparative Example 2

A method for preparing skin-friendly antibacterial fiber by recycling waste polyester, the skin-friendly antibacterial fiber comprising the following preparation steps:

(1) After the waste polyester fabric is crushed, it is washed with deionized water for 4 times, and dried at 80° C. for 3.5 hours to obtain polyester fragments; the polyester fragments, sodium bicarbonate, sodium hydroxide, ethylene glycol and titanium dioxide are mixed in a mass ratio of 1:2.2:1.5:8:0.02, stirred at 160° C. and 150 rpm for 1 hour under a nitrogen environment, cooled to 140° C. and filtered, the filtrate is vacuum distilled at 175° C., dried at 70° C. for 3.5 hours, deionized water is added and stirred until dissolved, the pH is adjusted to 4 with a hydrochloric acid solution with a mass fraction of 37%, vacuum filtered, washed with deionized water for 4 times, and dried at 100° C. for 5 hours to obtain terephthalic acid;

(2) Trimethylphosphine, acetone and sodium iodide were mixed in a mass ratio of 1:2.5:0.015, stirred at 200 rpm in a nitrogen atmosphere and heated to 40°C, 7-bromoheptanal (0.4 times the mass of trimethylphosphine) was added, the mixture was stirred for 2 hours, filtered, washed with ethyl acetate 4 times, ventilated for 45 minutes, and dried at 40°C for 6 hours to obtain a quaternary phosphine salt; chitosan, glacial acetic acid and deionized water were mixed in a mass ratio of 1:1:21, stirred at 25°C and 150 rpm for 12 hours to obtain an aqueous solution; sorbitan oleate and liquid paraffin were mixed in a mass ratio of 1:3.8, stirred at 10000 rpm for 3 minutes, and an aqueous solution (13.7 times the mass of sorbitan oleate) was added at a uniform rate within 15 minutes. The solution was stirred at 25°C and 150rpm for 3h, and a quaternary phosphonium salt with a mass of 1.5 times that of sorbitan oleate was uniformly added within 25, and the stirring was continued at 40°C for 4h. After natural cooling to room temperature, the mixture was centrifuged, washed with anhydrous ethanol and deionized water for 4 times respectively, and dried at 60°C for 24h to obtain pre-modified chitosan; the pre-modified chitosan, dimethyl sulfoxide and a sodium hydroxide solution with a mass fraction of 40% were mixed in a mass ratio of 1:8:20, and stirred at 40°C and 200rpm for 25min. Allyl chloride with a mass of 2.5 times that of the pre-modified chitosan was uniformly added within 35min, and the stirring was continued for 1h. After the mixture was centrifuged, the mixture was washed with anhydrous ethanol and deionized water alternately for 4 times, and dried at 60°C for 13h to obtain modified chitosan;

(3) The terephthalic acid, antimony trioxide and ethylene glycol obtained in step (1) are mixed in a mass ratio of 1:0.015:0.7, stirred at 135°C, 0.02MPa and 150rpm for 45min under a nitrogen environment, heated to 180°C and continued to stir for 1.5h, then heated to 245°C and continued to stir until the viscosity remains unchanged to obtain a modified polyester; the modified polyester is heated at 220°C until it is melted, 0.25 times the mass of the modified polyester modified chitosan is added and stirred at 250rpm for 1.5h, then 0.02 times the mass of the modified polyester potassium persulfate is added and continued to stir for 25min, extruded and spun by a twin-screw extruder, and after spinning is completed, the fiber is allowed to stand at 75°C for 7h, and naturally cooled to room temperature to obtain a spun fiber; the spun fiber is soaked in a sodium hypochlorite solution with a pH of 7.5 for 20min, washed 4 times with deionized water, and dried at 45°C for 2h to obtain a regenerated skin-friendly antibacterial fiber.

Comparative Example 3

A method for preparing skin-friendly antibacterial fiber by recycling waste polyester, the skin-friendly antibacterial fiber comprising the following preparation steps:

(1) After the waste polyester fabric is crushed, it is washed with deionized water for 4 times, and dried at 80° C. for 3.5 hours to obtain polyester fragments; the polyester fragments, sodium bicarbonate, sodium hydroxide, ethylene glycol and titanium dioxide are mixed in a mass ratio of 1:2.2:1.5:8:0.02, stirred at 160° C. and 150 rpm for 1 hour under a nitrogen environment, cooled to 140° C. and filtered, the filtrate is vacuum distilled at 175° C., dried at 70° C. for 3.5 hours, deionized water is added and stirred until dissolved, the pH is adjusted to 4 with a hydrochloric acid solution with a mass fraction of 37%, vacuum filtered, washed with deionized water for 4 times, and dried at 100° C. for 5 hours to obtain terephthalic acid;

(2) Trimethylphosphine, acetone and sodium iodide were mixed in a mass ratio of 1:2.5:0.015, stirred at 200 rpm in a nitrogen atmosphere and heated to 40°C, 7-bromoheptanal (0.4 times the mass of trimethylphosphine) was added, and the mixture was stirred for 2 hours and then filtered, washed with ethyl acetate 4 times, ventilated for 45 minutes, and dried at 40°C for 6 hours to obtain a quaternary phosphine salt; chitosan, glacial acetic acid and deionized water were mixed in a mass ratio of 1:1:21, stirred at 25°C and 150 rpm for 12 hours to obtain an aqueous solution ; Sorbitan oleate and liquid paraffin were mixed in a mass ratio of 1:3.8, stirred at 10000rpm for 3min, an aqueous solution of 13.7 times the mass of sorbitan oleate was added at a uniform rate within 15min, stirred at 25°C and 150rpm for 3h, a quaternary phosphate solution of 1.5 times the mass of sorbitan oleate was added at a uniform rate within 25, and stirring was continued at 40°C for 4h, cooled naturally to room temperature and centrifuged, washed with anhydrous ethanol and deionized water for 4 times respectively, and dried at 60°C for 24h to obtain modified chitosan;

(3) Allyl phosphine dichloride, ethyl p-aminobenzoate and 1,4-dioxane were mixed in a mass ratio of 1:4.05:5.5, stirred at 85°C and 250rpm for 12h under a nitrogen environment, and a 50% ethanol solution with a mass fraction of 4.5 times the mass of allyl phosphine dichloride and sodium hydroxide with a molar amount of 2.2 times that of allyl phosphine dichloride were added, the temperature was cooled to 80°C and the stirring was continued for 3h, a hydrochloric acid solution with a pH of 2 was added dropwise to adjust the pH of the solution to 3, and the solution was distilled under reduced pressure, washed with a hydrochloric acid solution with a pH of 2 and deionized water for 4 times respectively, dried at 65°C for 4h, cooled to room temperature and filtered to obtain a diacid precursor monomer;

(4) the terephthalic acid, diacid precursor monomer, antimony trioxide and ethylene glycol obtained in step (1) are mixed in a mass ratio of 1:0.5:0.015:0.7, stirred at 135°C, 0.02MPa and 150rpm for 45min under a nitrogen environment, heated to 180°C and continued to stir for 1.5h, then heated to 245°C and continued to stir at 85Pa until the viscosity remains unchanged, to obtain a modified polyester; the modified polyester is heated at 220°C until it is melted, and the modified polyester is added The modified chitosan with a mass of 0.25 times that of the ester was stirred at 250 rpm for 1.5 h, and then potassium persulfate with a mass of 0.02 times that of the modified polyester was added and stirred for 25 min. The fibers were extruded and spun using a twin-screw extruder. After the spinning was completed, the fibers were allowed to stand at 75 ° C for 7 h and naturally cooled to room temperature to obtain spun fibers. The spun fibers were immersed in a sodium hypochlorite solution with a pH of 7.5 for 20 min, washed 4 times with deionized water, and dried at 45 ° C for 2 h to obtain regenerated skin-friendly antibacterial fibers.

Comparative Example 4

A method for preparing skin-friendly antibacterial fiber by recycling waste polyester, the skin-friendly antibacterial fiber comprising the following preparation steps:

(1) After the waste polyester fabric is crushed, it is washed with deionized water for 4 times, and dried at 80° C. for 3.5 hours to obtain polyester fragments; the polyester fragments, sodium bicarbonate, sodium hydroxide, ethylene glycol and titanium dioxide are mixed in a mass ratio of 1:2.2:1.5:8:0.02, stirred at 160° C. and 150 rpm for 1 hour under a nitrogen environment, cooled to 140° C. and filtered, the filtrate is vacuum distilled at 175° C., dried at 70° C. for 3.5 hours, deionized water is added and stirred until dissolved, the pH is adjusted to 4 with a hydrochloric acid solution with a mass fraction of 37%, vacuum filtered, washed with deionized water for 4 times, and dried at 100° C. for 5 hours to obtain terephthalic acid;

(2) Allyl phosphine dichloride, ethyl p-aminobenzoate and 1,4-dioxane were mixed in a mass ratio of 1:4.05:5.5, stirred at 85°C and 250 rpm for 12 h under a nitrogen environment, and a 50% ethanol solution with a mass fraction of 4.5 times the mass of allyl phosphine dichloride and sodium hydroxide with a molar amount of 2.2 times that of allyl phosphine dichloride were added, the temperature was cooled to 80°C and the stirring was continued for 3 h, a hydrochloric acid solution with a pH of 2 was added dropwise to adjust the pH of the solution to 3, and the solution was distilled under reduced pressure, washed with a hydrochloric acid solution with a pH of 2 and deionized water for 4 times respectively, dried at 65°C for 4 h, cooled to room temperature and filtered to obtain a diacid precursor monomer;

(3) The terephthalic acid, diacid precursor monomer, antimony trioxide and ethylene glycol obtained in step (1) are mixed in a mass ratio of 1:0.5:0.015:0.7, stirred at 135°C, 0.02MPa and 150rpm for 45min under a nitrogen environment, heated to 180°C and continued to stir for 1.5h, then heated to 245°C and continued to stir at 85Pa until the viscosity remains unchanged to obtain a modified polyester; the modified polyester is heated at 220°C until it is melted, extruded and spun by a twin-screw extruder, and naturally cooled to room temperature to obtain a spun fiber; the spun fiber is immersed in a sodium hypochlorite solution with a pH of 7.5 for 20min, washed with deionized water 4 times, and dried at 45°C for 2h to obtain a regenerated skin-friendly antibacterial fiber.

Effect example

Table 1 below shows the analysis results of the flame retardant properties, antibacterial properties and water wash resistance of the skin-friendly antibacterial fibers of Examples 1 to 3 of the present invention and Comparative Examples 1 to 4.

Table 1

From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 1, it can be found that the skin-friendly antibacterial fiber prepared in the present invention has good flame retardant properties, antibacterial properties and water washability.

By comparison, the antibacterial rates of Examples 1, 2, and 3 are higher than those of Comparative Example 1, which indicates that the introduction of halamine precursors on the main chain to form halamine structures after immersion in sodium hypochlorite solution can destroy the cell membrane structure, interfere with the metabolism in the cells, and improve the antibacterial properties of the skin-friendly antibacterial fiber.

By comparison, the limiting oxygen index, antibacterial rate, flame retardant performance retention rate and antibacterial performance retention rate of Examples 1, 2 and 3 are higher than that of Comparative Example 2, which shows that the diacid precursor monomer with a double bond synthesized by allyl phosphine dichloride participates in the polymerization together with the recovered terephthalic acid, and the double bond structure and phosphorus element are introduced into the polyester main chain. The double bond improves the binding force between the polyester main chain and the modified chitosan, and enhances the water washability of the skin-friendly antibacterial fiber; the phosphorus element can react with the burning gas phase to generate oxidation products of phosphorus compounds, form a gas phase barrier layer, and improve the flame retardant properties of the skin-friendly antibacterial fiber.

By comparison, the flame retardant performance retention rate and antibacterial performance retention rate of Examples 1, 2, and 3 are higher than that of Comparative Example 3, which shows that grafting allyl chloride on chitosan introduces a double bond structure that can be polymerized with the polyester main chain, thereby improving the binding force between the modified chitosan and the polyester main chain and improving the water washability of the skin-friendly antibacterial fiber.

By comparison, the limiting oxygen index, antibacterial rate, flame retardant retention rate and antibacterial retention rate of Examples 1, 2 and 3 are higher than those of Comparative Example 4, which shows that the quaternary phosphonium salt structure is grafted on chitosan, and the cationic part in the structure can interact with the negatively charged part in the cell membrane of the microorganism, destroy the cell membrane, and improve the antibacterial property of the skin-friendly antibacterial fiber; the introduced phosphorus element can effectively promote carbonization at high temperature, and improve the flame retardant property of the skin-friendly antibacterial fiber; at the same time, the quaternary phosphonium salt synthesized by 7-bromoheptanal containing a long hydrophobic carbon chain is used to improve the water wash resistance of the skin-friendly antibacterial fiber.

It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims (9)

1. A method for recycling and regenerating waste polyester to prepare skin-friendly antibacterial fiber, characterized in that the waste polyester is recycled and regenerated to prepare skin-friendly antibacterial fiber by spinning after reacting the recovered terephthalic acid, diacid precursor monomer, ethylene glycol and modified chitosan, and then soaking in a sodium hypochlorite solution to obtain it. 2. The method for preparing skin-friendly and antibacterial fiber by recycling and regenerating waste polyester according to claim 1 is characterized in that the terephthalic acid is obtained by alcohol-alkali combined depolymerization of waste polyester fabric. 3. The method for preparing skin-friendly and antibacterial fiber by recycling and regenerating waste polyester according to claim 1 is characterized in that the diacid precursor monomer is obtained by hydrolyzing and acidifying the reaction of allyl phosphine dichloride and ethyl p-aminobenzoate. 4. The method for preparing skin-friendly and antibacterial fiber by recycling and regenerating waste polyester according to claim 1, characterized in that the modified chitosan is obtained by first reacting trimethyl phosphine and 7-bromoheptanal to obtain a quaternary phosphonium salt, and then reacting the chitosan with the quaternary phosphonium salt and allyl chloride in sequence. 5. A method for preparing skin-friendly antibacterial fiber by recycling waste polyester, characterized in that it comprises the following preparation steps: (1) After the waste polyester fabric is crushed, it is washed with deionized water for 3 to 5 times, and dried at 75 to 85° C. for 3 to 4 hours to obtain polyester fragments; the polyester fragments, sodium bicarbonate, sodium hydroxide, ethylene glycol and titanium dioxide are mixed in a mass ratio of 1: (2.1 to 2.3): (1.4 to 1.6): (7 to 9): (0.01 to 0.03), stirred at 155 to 165° C. and 100 to 200 rpm for 0.5 to 1.5 hours under a nitrogen environment, cooled to 135 to 145° C., filtered, the filtrate is vacuum distilled at 170 to 180° C., dried at 65 to 75° C. for 3 to 4 hours, deionized water is added and stirred until dissolved, the pH is adjusted to 3 to 5 with a hydrochloric acid solution with a mass fraction of 36 to 38%, vacuum filtered, washed with deionized water for 3 to 5 times, and dried at 90 to 110° C. for 4 to 6 hours to obtain terephthalic acid; (2) trimethylphosphine, acetone and sodium iodide are mixed in a mass ratio of 1:(2-3):(0.01-0.02), stirred at 100-300 rpm in a nitrogen atmosphere and heated to 35-45° C., 7-bromoheptanal (0.3-0.5 times the mass of trimethylphosphine) is added, stirred for 1.5-2.5 hours, filtered, washed with ethyl acetate 3-5 times, ventilated for 30-60 minutes, and dried at 35-45° C. for 5-7 hours to obtain a quaternary phosphine salt; Chitosan, glacial acetic acid and deionized water were mixed in a mass ratio of 1: (0.5-1.5): (20-22), and stirred at 20-30°C and 100-200rpm for 11-13h to obtain an aqueous solution; sorbitan oleate and liquid paraffin were mixed in a mass ratio of 1: (3.7-3.9), and stirred at 9000-11000rpm for 2-4min, and sorbitan oleate (mass 13.6-1 3.8 times of aqueous phase solution, stirring at 20-30°C and 100-200rpm for 2-4h, adding 1-2 times of quaternary phosphonium salt of sorbitan oleate at a uniform speed within 20-30, stirring at 35-45°C for 3-5h, cooling naturally to room temperature and centrifuging, washing with anhydrous ethanol and deionized water for 3-5 times respectively, drying at 55-65°C for 23-25h, and obtaining pre-modified chitosan; pre-modified chitosan, dimethyl sulfoxide and 3 mass fraction of oleic acid are added. 5-45% sodium hydroxide solution is mixed in a mass ratio of 1:(7-9):(18-22), stirred at 35-45°C and 150-250 rpm for 20-30 min, 2-3 times the mass of pre-modified chitosan propylene chloride is added at a uniform speed within 30-40 min, stirring is continued for 0.5-1.5 h and then centrifuged, washed alternately with anhydrous ethanol and deionized water for 3-5 times, and dried at 55-65°C for 12-14 h to obtain modified chitosan; (3) Allyl phosphine dichloride, ethyl p-aminobenzoate and 1,4-dioxane are mixed in a mass ratio of 1:(4-4.1):(5-6), stirred at 84-86° C. and 200-300 rpm for 11-13 h under a nitrogen environment, and a mass fraction of 45-55% ethanol solution of 4-5 times the mass of allyl phosphine dichloride and a molar amount of sodium hydroxide of 2.1-2.3 times the molar amount of allyl phosphine dichloride are added, the temperature is lowered to 79-81° C. and stirring is continued for 2-4 h, a hydrochloric acid solution of pH 1.5-2.5 is added dropwise to adjust the solution pH to 2.5-3.5, and distilled under reduced pressure, washed 3-5 times with a hydrochloric acid solution of pH 1.5-2.5 and deionized water, respectively, and dried at 60-70° C. for 3-5 h, cooled to room temperature and filtered to obtain a diacid precursor monomer; (4) the terephthalic acid, diacid precursor monomer, antimony trioxide and ethylene glycol obtained in step (1) are mixed in a mass ratio of 1: (0.4-0.6): (0.01-0.02): (0.6-0.8), stirred at 130-140° C., 0.01-0.03 MPa, and 100-200 rpm for 40-50 min in a nitrogen environment, heated to 175-185° C. and continued to stir for 1-2 h, then heated to 240-250° C., 80-90 Pa, and continued to stir until the viscosity remains unchanged to obtain a modified polyester; the modified polyester is heated at 215-225° C. Heat until melted, add modified chitosan in an amount of 0.2 to 0.3 times the mass of the modified polyester, stir at 200 to 300 rpm for 1 to 2 hours, add potassium persulfate in an amount of 0.01 to 0.03 times the mass of the modified polyester, continue stirring for 20 to 30 minutes, extrude and spin with a twin-screw extruder, stand at 70 to 80° C. for 6 to 8 hours after spinning, cool naturally to room temperature, and obtain spun fibers; soak the spun fibers in a sodium hypochlorite solution with a pH of 7 to 8 for 15 to 25 minutes, wash with deionized water for 3 to 5 times, and dry at 40 to 50° C. for 1 to 3 hours to obtain regenerated skin-friendly antibacterial fibers. 6. The method for preparing skin-friendly antibacterial fiber by recycling waste polyester according to claim 5, characterized in that the reaction equation of the quaternary phosphite in step (2) is: 7. The method for preparing skin-friendly antibacterial fiber by recycling waste polyester according to claim 5, characterized in that the reaction equation of the pre-modified chitosan in step (2) is: 8. The method for preparing skin-friendly antibacterial fiber by recycling waste polyester according to claim 5, characterized in that the reaction equation of the modified chitosan in step (2) is: 9. The method for preparing skin-friendly antibacterial fiber by recycling waste polyester according to claim 5, characterized in that the reaction equation of the diacid precursor monomer in step (3) is: