A kind of reinforced flame-retardant recycled polyester fiber and preparation method thereof

Abstract

The invention provides a reinforced flame-retardant recycled polyester fiber and a preparation method thereof, which relates to the technical field of recycled polyester fibers, and comprises the following raw materials in parts by weight: 100 parts of recycled polyester, 12-18 parts of functional copolymer, 1-3 parts of compatibilizer, 3-5 parts of coupling agent, 0.6-1.2 parts of antioxidant, 5-10 parts of nanofiber, and 1-3 parts of quinoline yellow; the functional copolymer is prepared by free radical copolymerization of allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine, and methyl methacrylate. The reinforced flame-retardant recycled polyester fiber has good mechanical properties and flame retardancy, and sufficient aging resistance.

Description

Technical Field

[0001] The invention relates to the technical field of regenerated polyester fibers, and in particular to a reinforced flame-retardant regenerated polyester fiber and a preparation method thereof. Background Art

[0002] Polyethylene terephthalate is a semi-crystalline thermoplastic polymer material with excellent performance, which is widely used in chemical fiber, packaging, medicine, electronic machinery and other fields. While the polyester industry is developing rapidly, the problem of handling waste polyester products has come one after another. The huge stock of waste polyester products in society has not only brought great pressure to the ecological environment, but also caused serious waste of resources. It is under this situation that recycled polyester materials came into being, and its appearance has attracted widespread attention.

[0003] Recycled polyester material is obtained by removing the bottle cap, label and additives from polyester bottle flakes and then processing them using physical or chemical methods. It has the defects of high impurity content, wide molecular weight distribution, large viscosity range and difficult spinning. Polyester fiber has the advantages of high strength and good decontamination performance. It is widely used in clothing fabrics and other fields. It is currently the most widely used polyester material in the world. It can be seen that how to make recycled polyester fiber with good comprehensive performance and performance stability is particularly important.

[0004] Existing recycled polyester fibers generally have technical problems of insufficient strength and flame retardancy. In order to improve the strength and flame retardancy of recycled polyester fibers, it is mainly achieved by adding reinforcing fillers and flame retardants. However, the combustion of existing flame retardants will cause great pollution to the environment, and due to the compatibility problem between reinforcing fillers and flame retardants and recycled polyester substrates, the recycled polyester fibers produced are prone to phase separation during long-term use, which affects the service life.

[0005] In order to solve the above problems, the Chinese invention patent with the authorization announcement number CN103409844B discloses a method for preparing a reinforced flame-retardant regenerated polyester fiber, comprising: stirring and mixing the dried regenerated polyester, phosphorus-based flame retardant and nanomaterial at 30-180°C, and then extruding and granulating at 240-300°C to obtain a reinforced flame-retardant regenerated polyester composite material slice; drying the reinforced flame-retardant regenerated polyester composite material slice, and then cooling it to 40-90°C, adding a dispersant to obtain a spinning raw material, spinning, and drawing to obtain. The reinforced flame-retardant regenerated polyester slice provided by the invention has good spinning and excellent fiber quality; the nanomaterial used can produce a synergistic effect with the phosphorus-based flame retardant, which can effectively reduce the amount of flame retardant, thereby reducing costs, and can also play a reinforcing role, which can effectively improve the mechanical properties of the fiber. However, due to the dispersibility problem of the nanomaterial and the compatibility problem between the flame retardant and the nanomaterial and the polyester material, the aging resistance and mechanical properties of the fiber material still need to be further improved.

[0006] Therefore, it is necessary to seek a more effective method to prepare a reinforced flame-retardant recycled polyester fiber with good mechanical properties, flame retardancy and aging resistance and a preparation method thereof. Summary of the invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a reinforced flame-retardant regenerated polyester fiber with good mechanical properties, flame retardancy and sufficient aging resistance and a preparation method thereof.

[0008] The present invention can be implemented by the following technical solutions:

[0009] The reinforced flame-retardant recycled polyester fiber according to the present invention comprises the following raw materials in parts by weight: 100 parts of recycled polyester, 12-18 parts of functional copolymer, 1-3 parts of compatibilizer, 3-5 parts of coupling agent, 0.6-1.2 parts of antioxidant, 5-10 parts of nanofiber and 1-3 parts of quinoline yellow; the functional copolymer is prepared by free radical copolymerization of allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine and methyl methacrylate.

[0010] Preferably, the recycled polyester is made from recycled polyester bottle flakes that are sequentially sorted, crushed, cleaned and dried.

[0011] Preferably, the preparation method of the functional copolymer comprises the following steps: adding allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine, methyl methacrylate and an initiator to a high boiling point solvent, stirring and reacting at 60-70°C in an inert gas atmosphere for 4-6 hours, then precipitating in water, and washing the precipitated polymer with ethanol for 3-6 times, and finally drying in a vacuum drying oven at 85-95°C to constant weight to obtain a functional copolymer.

[0012] Preferably, the mass ratio of allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine, methyl methacrylate, initiator and high boiling point solvent is 2:(0.8-1.2):(1-3):(0.04-0.07):(15-30).

[0013] Preferably, the initiator is azobisisobutyronitrile; the high boiling point solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone; and the inert gas is any one of nitrogen, helium, neon, and argon.

[0014] Preferably, the compatibilizer is at least one of PE-g-ST and PE-g-MAH.

[0015] Preferably, the coupling agent is at least one of silane coupling agent KH550, silane coupling agent KH560 and silane coupling agent KH570.

[0016] Preferably, the antioxidant is at least one of antioxidant 1010, antioxidant 168, and antioxidant 1076.

[0017] Preferably, the nanofiber is at least one of nano-boron fiber and nano-carbon fiber; the average diameter of the nanofiber is 60-100nm and the length is 1-5mm.

[0018] The present invention also provides a method for preparing the reinforced flame-retardant recycled polyester fiber, comprising the following steps:

[0019] Step S1, after uniformly mixing all the raw materials except quinoline yellow, blending and melting through a screw extruder, spinning the melt through a special-shaped hole spinneret, and obtaining functional filaments after drawing and shaping;

[0020] Step S2, soaking the functional filaments prepared in step S1 in a quinoline yellow solution with a mass percentage concentration of 10-20wt% at 50-60°C for 20-40 hours, taking them out and drying them to obtain reinforced flame-retardant regenerated polyester fibers.

[0021] Preferably, the spinning temperature of the spinning molding in step S1 is 240-290° C., and the spinning speed is 2200-2800 m / min.

[0022] Preferably, the temperature of the stretching and setting in step S1 is 60-66°C.

[0023] Preferably, the drying in step S2 is performed at 95-105° C. to a constant weight.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The method for preparing the reinforced flame-retardant recycled polyester fiber disclosed in the present invention has simple process, convenient operation and control, high preparation efficiency and finished product qualification rate, low dependence on equipment, and is suitable for continuous large-scale production.

[0026] (2) The flame retardant component introduced into the reinforced flame retardant recycled polyester fiber disclosed in the present invention is an organic component, which has good compatibility with polyester. The functional copolymer is made of allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine, and methyl methacrylate through free radical copolymerization, and phenylphosphine bromide, pyrimidine and ester structures are simultaneously introduced into the molecular chain. These structures cooperate with each other to give the polyester fiber excellent flame retardancy, aging resistance and mechanical properties; the added nanofibers can further enhance and synergize with the above functional copolymer to further improve the flame retardancy and mechanical properties. In addition, the introduced phosphine bromide cationic structure can also provide reaction sites for subsequent cross-linking and curing.

[0027] (3) The enhanced flame-retardant regenerated polyester fiber disclosed in the present invention is immersed in a quinoline yellow solution during the preparation process to achieve ion crosslinking, and introduces quinoline and indane dione structures on the surface of the fiber material. These structures interact with the phenylphosphine bromide, pyrimidine and ester structures in the fiber material to further improve the flame retardancy, mechanical properties and aging resistance of the fiber. Through ion exchange, the bromide ions in the fiber structure will be taken out by water in the form of sodium bromide, making it safe and non-toxic during use and combustion. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention, the product of the present invention is further described in detail below in conjunction with embodiments.

[0029] Example 1

[0030] A reinforced flame-retardant recycled polyester fiber is made of the following raw materials in parts by weight: 100 parts of recycled polyester, 12 parts of functional copolymer, 1 part of compatibilizer, 3 parts of coupling agent, 0.6 parts of antioxidant, 5 parts of nanofiber and 1 part of quinoline yellow; the functional copolymer is made of allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine and methyl methacrylate through free radical copolymerization.

[0031] The regenerated polyester is made from recycled polyester bottle flakes that are sorted, crushed, cleaned and dried in sequence.

[0032] The preparation method of the functional copolymer comprises the following steps: adding allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine, methyl methacrylate, and an initiator to a high boiling point solvent, stirring and reacting at 60°C in an inert gas atmosphere for 4 hours, then precipitating in water, washing the precipitated polymer with ethanol for 3 times, and finally drying it in a vacuum drying oven at 85°C to constant weight to obtain a functional copolymer; the mass ratio of allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine, methyl methacrylate, initiator, and high boiling point solvent is 2:0.8:1:0.04:15; the initiator is azobisisobutyronitrile; the high boiling point solvent is dimethyl sulfoxide; and the inert gas is nitrogen. Through GPC testing, the M of the copolymer n =13180 g / mol, M W / M n =1.281; quantitative element analysis confirmed that the mass ratio of the structural units introduced by allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine and methyl methacrylate in the copolymer was 1.98:0.79:0.98.

[0033] The compatibilizer is PE-g-ST; the coupling agent is silane coupling agent KH550; the antioxidant is antioxidant 1010; the nanofiber is nano-boron fiber; the average diameter of the nanofiber is 60nm and the length is 1mm.

[0034] A method for preparing the reinforced flame-retardant recycled polyester fiber comprises the following steps:

[0035] Step S1, after uniformly mixing all the raw materials except quinoline yellow, blending and melting through a screw extruder, spinning the melt through a special-shaped hole spinneret, and obtaining functional filaments after drawing and shaping;

[0036] Step S2, soaking the functional filaments prepared in step S1 in a 10 wt% quinoline yellow solution at 50° C. for 20 hours, taking them out and drying them to obtain a reinforced flame-retardant regenerated polyester fiber.

[0037] The spinning temperature of the spinning molding in step S1 is 240° C. and the spinning speed is 2200 m / min; the temperature of the drawing and shaping in step S1 is 60° C.; and the drying in step S2 is performed at 95° C. to constant weight.

[0038] Example 2

[0039] A reinforced flame-retardant recycled polyester fiber is made of the following raw materials in parts by weight: 100 parts of recycled polyester, 14 parts of functional copolymer, 1.5 parts of compatibilizer, 3.5 parts of coupling agent, 0.8 parts of antioxidant, 6 parts of nanofiber, and 1.5 parts of quinoline yellow; the functional copolymer is made of allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine, and methyl methacrylate through free radical copolymerization.

[0040] The regenerated polyester is made from recycled polyester bottle flakes that are sorted, crushed, cleaned and dried in sequence.

[0041] The preparation method of the functional copolymer comprises the following steps: adding allyl triphenylphosphine bromide, (9CI)-2-vinyl pyrimidine, methyl methacrylate and an initiator into a high boiling point solvent, stirring and reacting at 63°C in an inert gas atmosphere for 4.5 hours, then precipitating in water, washing the precipitated polymer with ethanol for 4 times, and finally drying in a vacuum drying oven at 88°C to constant weight to obtain the functional copolymer; the mass ratio of allyl triphenylphosphine bromide, (9CI)-2-vinyl pyrimidine, methyl methacrylate, initiator and high boiling point solvent is 2:0.9:1.5:0.05:17; the initiator is azobisisobutyronitrile; the high boiling point solvent is N,N-dimethylformamide; and the inert gas is helium.

[0042] The compatibilizer is PE-g-MAH; the coupling agent is silane coupling agent KH560; the antioxidant is antioxidant 168; the nanofiber is nanocarbon fiber; the average diameter of the nanofiber is 70nm and the length is 2mm.

[0043] A method for preparing the reinforced flame-retardant recycled polyester fiber comprises the following steps:

[0044] Step S1, after uniformly mixing all the raw materials except quinoline yellow, blending and melting through a screw extruder, spinning the melt through a special-shaped hole spinneret, and obtaining functional filaments after drawing and shaping;

[0045] Step S2, soaking the functional filaments prepared in step S1 in a quinoline yellow solution with a mass percentage concentration of 13 wt% at 53° C. for 25 hours, taking them out and drying them to obtain reinforced flame-retardant regenerated polyester fibers.

[0046] The spinning temperature of the spinning molding in step S1 is 260° C. and the spinning speed is 2400 m / min; the temperature of the drawing and shaping in step S1 is 62° C.; and the drying in step S2 is performed at 98° C. to constant weight.

[0047] Example 3

[0048] A reinforced flame-retardant recycled polyester fiber is made of the following raw materials in parts by weight: 100 parts of recycled polyester, 15 parts of functional copolymer, 2 parts of compatibilizer, 4 parts of coupling agent, 0.9 parts of antioxidant, 7.5 parts of nanofiber and 2 parts of quinoline yellow; the functional copolymer is made of allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine and methyl methacrylate through free radical copolymerization.

[0049] The regenerated polyester is made from recycled polyester bottle flakes that are sorted, crushed, cleaned and dried in sequence.

[0050] The preparation method of the functional copolymer comprises the following steps: adding allyl triphenylphosphine bromide, (9CI)-2-vinyl pyrimidine, methyl methacrylate and an initiator into a high boiling point solvent, stirring and reacting for 5 hours at 65°C in an inert gas atmosphere, then precipitating in water, washing the precipitated polymer with ethanol for 5 times, and finally drying in a vacuum drying oven at 90°C to constant weight to obtain the functional copolymer; the mass ratio of allyl triphenylphosphine bromide, (9CI)-2-vinyl pyrimidine, methyl methacrylate, initiator and high boiling point solvent is 2:1:2:0.055:23; the initiator is azobisisobutyronitrile; the high boiling point solvent is N-methylpyrrolidone; and the inert gas is neon.

[0051] The compatibilizer is PE-g-ST; the coupling agent is silane coupling agent KH570; the antioxidant is antioxidant 1076; the nanofiber is nano-boron fiber; the average diameter of the nanofiber is 80nm and the length is 3.5mm.

[0052] A method for preparing the reinforced flame-retardant recycled polyester fiber comprises the following steps:

[0053] Step S1, after uniformly mixing all the raw materials except quinoline yellow, blending and melting through a screw extruder, spinning the melt through a special-shaped hole spinneret, and obtaining functional filaments after drawing and shaping;

[0054] Step S2, soaking the functional filaments prepared in step S1 in a 15 wt% quinoline yellow solution at 55° C. for 30 hours, taking them out and drying them to obtain a reinforced flame-retardant regenerated polyester fiber.

[0055] The spinning temperature of the spinning molding in step S1 is 270° C. and the spinning speed is 2600 m / min; the temperature of the drawing and shaping in step S1 is 64° C.; the drying in step S2 is performed at 100° C. to constant weight.

[0056] Example 4

[0057] A reinforced flame-retardant recycled polyester fiber is made of the following raw materials in parts by weight: 100 parts of recycled polyester, 17 parts of functional copolymer, 2.5 parts of compatibilizer, 4.5 parts of coupling agent, 1.1 parts of antioxidant, 9 parts of nanofiber and 2.5 parts of quinoline yellow; the functional copolymer is made of allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine and methyl methacrylate through free radical copolymerization.

[0058] The regenerated polyester is made from recycled polyester bottle flakes that are sorted, crushed, cleaned and dried in sequence.

[0059] The preparation method of the functional copolymer comprises the following steps: adding allyl triphenylphosphine bromide, (9CI)-2-vinyl pyrimidine, methyl methacrylate and an initiator to a high boiling point solvent, stirring and reacting at 68°C in an inert gas atmosphere for 5.5 hours, then precipitating in water, washing the precipitated polymer with ethanol for 6 times, and finally drying in a vacuum drying oven at 93°C to constant weight to obtain the functional copolymer; the mass ratio of allyl triphenylphosphine bromide, (9CI)-2-vinyl pyrimidine, methyl methacrylate, initiator and high boiling point solvent is 2:1.1:2.5:0.065:28; the initiator is azobisisobutyronitrile; the high boiling point solvent is a mixture of dimethyl sulfoxide, N,N-dimethylformamide and N-methylpyrrolidone in a mass ratio of 1:3:2; and the inert gas is argon.

[0060] The compatibilizer is a mixture of PE-g-ST and PE-g-MAH in a mass ratio of 3:5; the coupling agent is a mixture of silane coupling agent KH550, silane coupling agent KH560 and silane coupling agent KH570 in a mass ratio of 1:3:5; the antioxidant is a mixture of antioxidant 1010, antioxidant 168 and antioxidant 1076 in a mass ratio of 1:2:3; the nanofiber is a mixture of nano-boron fiber and nano-carbon fiber in a mass ratio of 1:3; the average diameter of the nanofiber is 90nm and the length is 4mm.

[0061] A method for preparing the reinforced flame-retardant recycled polyester fiber comprises the following steps:

[0062] Step S1, after uniformly mixing all the raw materials except quinoline yellow, blending and melting through a screw extruder, spinning the melt through a special-shaped hole spinneret, and obtaining functional filaments after drawing and shaping;

[0063] Step S2, soaking the functional filaments prepared in step S1 in a quinoline yellow solution with a mass percentage concentration of 18 wt% at 58° C. for 35 hours, taking them out and drying them to obtain reinforced flame-retardant regenerated polyester fibers.

[0064] The spinning temperature of the spinning molding in step S1 is 280° C. and the spinning speed is 2700 m / min; the temperature of the drawing and shaping in step S1 is 65° C.; the drying in step S2 is performed at 103° C. to constant weight.

[0065] Example 5

[0066] A reinforced flame-retardant recycled polyester fiber is made of the following raw materials in parts by weight: 100 parts of recycled polyester, 18 parts of functional copolymer, 3 parts of compatibilizer, 5 parts of coupling agent, 1.2 parts of antioxidant, 10 parts of nanofiber and 3 parts of quinoline yellow; the functional copolymer is made of allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine and methyl methacrylate through free radical copolymerization.

[0067] The regenerated polyester is made from recycled polyester bottle flakes that are sorted, crushed, cleaned and dried in sequence.

[0068] The preparation method of the functional copolymer comprises the following steps: adding allyl triphenylphosphine bromide, (9CI)-2-vinyl pyrimidine, methyl methacrylate and an initiator into a high boiling point solvent, stirring and reacting for 6 hours at 70°C in an inert gas atmosphere, then precipitating in water, washing the precipitated polymer with ethanol for 6 times, and finally drying in a vacuum drying oven at 95°C to constant weight to obtain the functional copolymer; the mass ratio of allyl triphenylphosphine bromide, (9CI)-2-vinyl pyrimidine, methyl methacrylate, initiator and high boiling point solvent is 2:1.2:3:0.07:30; the initiator is azobisisobutyronitrile; the high boiling point solvent is dimethyl sulfoxide; and the inert gas is nitrogen.

[0069] The compatibilizer is PE-g-ST; the coupling agent is silane coupling agent KH550; the antioxidant is antioxidant 168; the nanofiber is nanocarbon fiber; the average diameter of the nanofiber is 100nm and the length is 5mm.

[0070] A method for preparing the reinforced flame-retardant recycled polyester fiber comprises the following steps:

[0071] Step S1, after uniformly mixing all the raw materials except quinoline yellow, blending and melting through a screw extruder, spinning the melt through a special-shaped hole spinneret, and obtaining functional filaments after drawing and shaping;

[0072] Step S2, soaking the functional filaments prepared in step S1 in a 20wt% quinoline yellow solution at 60°C for 40 hours, taking them out and drying them to obtain a reinforced flame-retardant regenerated polyester fiber.

[0073] The spinning temperature of the spinning molding in step S1 is 290° C. and the spinning speed is 2800 m / min; the temperature of the drawing and shaping in step S1 is 66° C.; the drying in step S2 is performed at 105° C. to constant weight.

[0074] Comparative Example 1

[0075] A reinforced flame-retardant regenerated polyester fiber and a preparation method thereof, which are substantially the same as those in Example 1, except that quinoline yellow is not added.

[0076] Comparative Example 2

[0077] A reinforced flame-retardant regenerated polyester fiber and a preparation method thereof, which are substantially the same as those in Example 1, except that (9CI)-2-vinylpyrimidine is not added.

[0078] At the same time, in order to evaluate the specific technical effect of the reinforced flame-retardant regenerated polyester fiber of the present invention, relevant performance tests were carried out on each example of reinforced flame-retardant regenerated polyester fiber. The test results are shown in Table 1, and the test method is as follows: the flame retardancy of each product is tested according to GB / T5454-1997 "Textile Combustion Performance Test Oxygen Index Method"; the mechanical properties are tested according to GB / T 14344-2022 "Chemical Fiber Filament Tensile Performance Test Method", and the specific test conditions are: the pre-tension value is set to 5cN, the clamping length is set to 250mm, and the stretching rate is set to 250mm / min. Each group of fiber samples is tested 10-20 times until stable data is obtained, and the CV value is required to be kept within 15%; the aging resistance is to place each product at 85°C for 100 hours, cool it to room temperature, and test the breaking strength again according to the above-mentioned mechanical property test method, and calculate the retention rate of the breaking strength after aging. The larger the value, the better the aging resistance.

[0079] Table 1

[0080] project Breaking strength (cN / dtex) Limiting oxygen index (%) Aging resistance (%) Example 1 3.9 32.6 99.0 Example 2 4.1 33.1 99.4 Example 3 4.4 33.8 99.6 Example 4 4.5 34.2 99.7 Example 5 4.7 34.8 99.9 Comparative Example 1 3.1 30.1 97.3 Comparative Example 2 3.4 29.7 96.8

[0081] It can be seen from Table 1 that the reinforced flame-retardant regenerated polyester fiber disclosed in the embodiment of the present invention has better breaking strength, aging resistance and flame retardancy than the comparative product, and the addition of quinoline yellow and (9CI)-2-vinylpyrimidine is beneficial to improving the above properties.

[0082] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as described above. However, any technician familiar with the profession can make some changes, modifications and evolutions of the technical content disclosed above without departing from the scope of the technical solution of the present invention, which are all equivalent embodiments of the present invention. At the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A reinforced flame-retardant recycled polyester fiber, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of recycled polyester, 12-18 parts of functional copolymer, 1-3 parts of compatibilizer, 3-5 parts of coupling agent, 0.6-1.2 parts of antioxidant, 5-10 parts of nanofiber and 1-3 parts of quinoline yellow; the functional copolymer is prepared by free radical copolymerization of allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine and methyl methacrylate; the preparation method of the functional copolymer comprises the following steps: mixing allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine and methyl methacrylate; Methyl olefinate and an initiator are added to a high boiling point solvent, stirred and reacted at 60-70° C. in an inert gas atmosphere for 4-6 hours, then precipitated in water, and the precipitated polymer is washed with ethanol for 3-6 times, and finally dried in a vacuum drying oven at 85-95° C. to constant weight to obtain a functional copolymer; the mass ratio of allyl triphenylphosphine bromide, (9CI)-2-vinylpyrimidine, methyl methacrylate, initiator, and high boiling point solvent is 2:(0.8-1.2):(1-3):(0.04-0.07):(15-30); The method for preparing the reinforced flame-retardant recycled polyester fiber comprises the following steps: Step S1, after uniformly mixing all the raw materials except quinoline yellow, blending and melting through a screw extruder, spinning the melt through a special-shaped hole spinneret, and obtaining functional filaments after drawing and shaping; Step S2, soaking the functional filaments prepared in step S1 in a quinoline yellow solution with a mass percentage concentration of 10-20wt% at 50-60°C for 20-40 hours, taking them out and drying them to obtain reinforced flame-retardant regenerated polyester fibers.

2. The reinforced flame-retardant regenerated polyester fiber according to claim 1, characterized in that: The regenerated polyester is made from recycled polyester bottle flakes that are sorted, crushed, cleaned and dried in sequence.

3. The reinforced flame-retardant regenerated polyester fiber according to claim 1, characterized in that: The initiator is azobisisobutyronitrile; the high boiling point solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, and N-methylpyrrolidone; and the inert gas is any one of nitrogen, helium, neon, and argon.

4. The reinforced flame-retardant regenerated polyester fiber according to claim 1, characterized in that: The compatibilizer is at least one of PE-g-ST and PE-g-MAH; the coupling agent is at least one of silane coupling agent KH550, silane coupling agent KH560 and silane coupling agent KH570.

5. The reinforced flame-retardant regenerated polyester fiber according to claim 1, characterized in that: The antioxidant is at least one of antioxidant 1010, antioxidant 168, and antioxidant 1076; the nanofiber is at least one of nano-boron fiber and nano-carbon fiber; the average diameter of the nanofiber is 60-100nm, and the length is 1-5mm.

6. The reinforced flame-retardant regenerated polyester fiber according to claim 1, characterized in that: The spinning temperature of the spinning molding in step S1 is 240-290°C, and the spinning speed is 2200-2800m / min; the temperature of the drawing and shaping in step S1 is 60-66°C.

7. The reinforced flame-retardant regenerated polyester fiber according to claim 1, characterized in that: The drying in step S2 is performed at 95-105° C. to a constant weight.