Flame-retardant antibacterial chenille yarn and production process thereof

Abstract

The invention relates to the technical field of yarns, and discloses a flame-retardant antibacterial chenille yarn and a production process thereof. The chenille yarn is prepared by twisting flame-retardant polyester fibers serving as core yarns and modified polyimide serving as camlet. The flame-retardant polyester fiber is used as the core wire, so that the yarn has higher strength, toughness and antibacterial property; the modified polyimide is used as the camlet, and a phosphate group and a quaternary ammonium salt antibacterial agent are introduced into a branched chain of the camlet, so that the flame retardant property and the antibacterial property of the yarn are further improved. Therefore, the chenille yarn prepared by the invention can be used for producing textiles such as bedding articles, carpets, wall ornaments, curtains and the like through spinning, and has excellent antibacterial property and flame retardant property.

Description

Technical Field

[0001] The invention relates to the technical field of yarns, and in particular to a flame-retardant and antibacterial chenille yarn and a production process thereof. Background Art

[0002] Chenille yarn is made by twisting the core yarn and mixing the feather yarn in the middle of the core yarn. Chenille yarn is made into fabrics and can be used for bedding, interior decoration accessories, such as bed blankets, carpets, sofa covers, curtains, etc. However, with the increase in actual demand, the requirements for some properties of chenille yarn, such as flame retardant properties and antibacterial properties, are gradually increasing. Therefore, the yarn needs to be modified to improve its related properties.

[0003] At present, most chenille yarns on the market are made of acrylic and polyester. For example, using polyester (polyester fiber) as the core can make the yarn have the advantages of polyester fiber, but polyester fiber has certain flammability. Considering the actual use needs, it needs to be treated to improve its flame retardant properties. The choice of feather yarn generally includes polyimide fiber, polyetheretherketone fiber, polyphenylene sulfide fiber, etc. This application selects polyimide fiber with certain antibacterial and flame retardant properties as feather yarn, and at the same time modifies it, such as: introducing antibacterial structure and flame retardant phosphate ester on the side chain, so as to further improve the antibacterial and flame retardant properties of polyimide fiber. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a flame retardant and antibacterial chenille yarn and a production process thereof.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A flame-retardant and antibacterial chenille yarn comprises a core yarn and a feather yarn, wherein the core yarn is a flame-retardant polyester fiber and the feather yarn is a modified polyimide fiber; The flame retardant polyester fiber is prepared by the following steps: Weigh the raw materials by weight, blend 35-45 parts of polyester and 10-15 parts of flame retardant masterbatch at 40°C for 60 minutes, vacuum dry, add 1-2 parts of cross-linking agent, blend at 70-80°C for 1-2 hours to obtain a mixture, and then melt-extrude the obtained mixture through a screw extruder, and then spin and heat-set the obtained melt to obtain a flame-retardant polyester fiber; The modified polyimide fiber is prepared by the following steps: Step A1, tris(hydroxymethyl)aminomethane and triethylamine are stirred evenly in dichloromethane, diphenyl chlorophosphonate is added dropwise at 0-5°C and stirred for 1 hour, and then stirred at room temperature for 12 hours. After the reaction is completed, the mixture is filtered, washed and dried to obtain a phosphorus-containing monomer; Furthermore, the usage ratio of trishydroxymethylaminomethane, triethylamine, dichloromethane and diphenyl chlorophosphonate is 0.1-0.2 mol: 0.1-0.3 mol: 500 mL: 0.1-0.2 mol.

[0006] Step A2, slowly heating the phosphorus-containing monomer, terminal ester quaternary ammonium salt, dibutyltin dilaurate and p-hydroxyanisole to 120° C. under stirring conditions, and maintaining the top temperature of the fractionation column at 55-65° C., keeping the reaction for 2-5 hours, and after the reaction is completed, performing reduced pressure distillation to obtain a terminal hydroxyl functional monomer; Furthermore, the usage ratio of the phosphorus-containing monomer, the terminal ester quaternary ammonium salt, dibutyltin dilaurate and p-hydroxyanisole is 0.01-0.02 mol: 0.01-0.06 mol: 0.08-0.16 g: 0.001 g.

[0007] Step A3, adding p-chloronitrobenzene to DMF and stirring to mix evenly, recorded as solution A; under nitrogen conditions, adding terminal hydroxyl functional monomer, DMF and potassium carbonate into a flask and stirring for 10 minutes, then slowly adding solution A dropwise, and raising the system temperature to 100° C. to react for 5-6 hours. After the reaction is completed, slowly adding the reaction solution into ice water to precipitate solids, filtering and drying, and then performing column chromatography separation, collecting the chromatographic solution and performing vacuum rotary evaporation to obtain intermediate product 1; Furthermore, the usage ratio of the terminal hydroxyl functional monomer, DMF, potassium carbonate and solution A is 0.01-0.02 mol: 200 mL: 1.5-3 g: 100 mL, and the usage ratio of p-chloronitrobenzene and DMF in solution A is 0.02-0.04 mol: 100 mL.

[0008] Step A4, add the intermediate product 1, 1,4-dioxane and Raney nickel into a reactor and stir evenly, introduce nitrogen and hydrogen in sequence, and raise the system temperature to 80°C to react for 7 hours. After the reaction is completed, filter, add ice water to the filtrate to precipitate solids, filter and vacuum dry to obtain the intermediate product 2; Furthermore, the usage ratio of the intermediate product 1, 1,4-dioxane and Raney nickel is 8-12 g:100 mL:0.7-1.1 g.

[0009] Step A5, under nitrogen conditions, add the intermediate product 2 and dimethylacetamide to a reactor and stir for 15-25 minutes, add pyromellitic anhydride in batches, and control the system temperature to react for 2 hours at 0°C, and then react at room temperature for 6-10 hours. After the reaction is completed, vacuum rotary evaporation is performed, and then a mixed solution of DMF and 1-methyl-2-pyrrolidone is added and stirred for 15-25 minutes, and then the pressure is reduced and filtered to obtain a spinning solution. The spinning solution is passed through a spinneret for wet spinning, and the obtained fiber is washed with water, and then placed in a tubular furnace for hot drawing, and finally the fiber is collected to obtain a modified polyimide fiber; Further, the usage ratio of the intermediate product 2, dimethylacetamide, pyromellitic dianhydride, DMF and 1-methyl-2-pyrrolidone is 8-12 g: 100 mL: 4.5-5.5 g: 90 mL: 30 mL; Furthermore, during the hot stretching process, the first stretching temperature is 180-200°C, the stretching ratio is 3, the second stretching temperature is 240-280°C, the stretching ratio is 3, and the third stretching temperature is 320-360°C, the stretching ratio is 1.

[0010] The terminal ester group quaternary ammonium salt is prepared by the following steps: Add methyl 3-chloropropionate and N, N-dimethylpropylamine into a reactor, add dichloromethane as a solvent, reflux at 90-100°C for 5-8h, and after the reaction is completed, a terminal ester quaternary ammonium salt is obtained; Furthermore, the usage ratio of methyl 3-chloropropionate, N,N-dimethylpropylamine and dichloromethane is 0.1 mol:0.11 mol:20 mL.

[0011] A method for preparing flame-retardant and antibacterial chenille yarn comprises the following steps: Two flame-retardant polyester fibers are used as core threads and twisted at a twist of 200-600 twists / meter, and modified polyimide fiber is sandwiched between the two core threads as feather yarn, and the axial density of the feather yarn is 600-1200 yarns / cm, so as to obtain flame-retardant and antibacterial chenille yarn.

[0012] Beneficial effects of the present invention: The chenille yarn of the present invention is prepared by twisting flame-retardant polyester fiber as a core wire and modified polyimide as a feather yarn; the flame-retardant polyester fiber as a core wire gives the yarn higher strength, toughness and antibacterial properties; the modified polyimide as a feather yarn, by introducing phosphate groups and quaternary ammonium salt antibacterial agents into its side chains, further improves the flame retardant and antibacterial properties of the yarn. Therefore, the chenille yarn prepared by the present invention can be spun to produce textiles such as bedding, carpets, wall decorations, curtains, etc., and has excellent antibacterial and flame retardant properties.

[0013] In the modified polyimide fiber, firstly, the reaction between the amino group in trishydroxymethylaminomethane and the chlorine atom in diphenyl chlorophosphonate is used to generate a phosphorus-containing monomer; secondly, the hydroxyl group in the phosphorus-containing monomer is used to react with the ester group in the terminal ester quaternary ammonium salt to generate a terminal hydroxyl functional monomer; thirdly, the hydroxyl group in the terminal hydroxyl functional monomer is used to react with the chlorine atom in p-chloronitrobenzene to generate an intermediate product 1 containing an ether bond; thirdly, Raney nickel is used as a catalyst to convert the nitro group into an amino group by catalytic hydrogenation to generate an intermediate product 2; finally, the intermediate product 2 and pyromellitic anhydride are used as raw materials, and the two are subjected to a condensation reaction to generate polyimide. Modified polyimide is used as feather yarn to improve the flame retardant and antibacterial properties of the yarn; phosphate groups are introduced into the side chains of polyimide. Phosphate will undergo thermal decomposition at high temperatures, and the generated water molecules and acidic substances can dilute combustibles. The released gases can isolate oxygen and dilute combustible gases, thereby producing a flame retardant effect. At the same time, phosphate can also form a dense carbon layer when burning, effectively preventing combustibles from contacting the outside air, further reducing the possibility of combustion; quaternary ammonium salt structure is introduced into polyimide by chemical bonding, giving polyimide better antibacterial properties. This is because chemical bonding grafting avoids the problem of reduced antibacterial properties of traditional antibacterial yarns after repeated washing. At the same time, the terminal ester quaternary ammonium salt antibacterial agent can use quaternary ammonium salt cations to adsorb negatively charged bacteria and aggregate on the cell wall, producing a chamber resistance effect, resulting in bacterial growth inhibition and death, thereby improving the antibacterial properties of polyimide; in addition, flexible ether bonds are introduced into the main chain of the polyimide molecule to improve the processing properties of polyimide fibers. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0015] (1) The ester-terminated quaternary ammonium salt is prepared by the following steps: 0.1 mol of methyl 3-chloropropionate and 0.11 mol of N,N-dimethylpropylamine were added into the reactor, and then 20 mL of dichloromethane was added as solvent. The mixture was refluxed at 90° C. for 7 h. After the reaction was completed, a terminal ester quaternary ammonium salt was obtained.

[0016] (2) The flame retardant polyester fiber is prepared by the following steps: The raw materials were weighed by weight, 35 parts of polyester and 10 parts of flame retardant masterbatch (Flame retardant masterbatch 51443 of Shenzhen Jinzhicheng Plastic Technology Co., Ltd.) were blended at 40°C for 60 minutes, and then vacuum dried. 1 part of triallyl isocyanurate was added and blended at 70°C for 1 hour to obtain a mixture. The mixture was then melt-extruded through a screw extruder, and the melt was spun and heat-set to obtain flame-retardant polyester fiber.

[0017] (3) The modified polyimide fiber is prepared by the following steps: Step A1, 0.1 mol of tris(hydroxymethyl)aminomethane and 0.1 mol of triethylamine are stirred evenly in 500 mL of dichloromethane, 0.1 mol of diphenyl chlorophosphonate is added dropwise at 0°C and stirred for 1 hour, and then stirred at room temperature for 12 hours. After the reaction is completed, the mixture is filtered, washed and dried to obtain a phosphorus-containing monomer; Step A2, slowly heating 0.01 mol of phosphorus-containing monomer, 0.01 mol of terminal ester quaternary ammonium salt, 0.08 g of dibutyltin dilaurate and 0.001 g of p-hydroxyanisole to 120° C. under stirring conditions, maintaining the top temperature of the fractionation column at 55° C., and keeping the reaction for 2 hours. After the reaction is completed, vacuum distillation is performed to obtain a terminal hydroxyl functional monomer; Step A3, adding 0.02 mol of p-chloronitrobenzene to 100 mL of DMF and stirring to mix evenly, recorded as solution A; under nitrogen conditions, adding 0.01 mol of terminal hydroxyl functional monomer, 200 mL of DMF and 1.5 g of potassium carbonate into a flask and stirring for 10 min, then slowly adding 100 mL of solution A dropwise, and raising the system temperature to 100 ° C. to react for 5 h. After the reaction is completed, the reaction solution is slowly added to ice water to precipitate solids, filtered and dried, and then separated by column chromatography, and the chromatographic liquid is collected and evaporated under reduced pressure to obtain intermediate 1; Step A4, 8 g of intermediate product 1, 100 mL of 1,4-dioxane and 0.7 g of Raney nickel were added to a reactor and stirred evenly, nitrogen and hydrogen were introduced in sequence, and the system temperature was raised to 80 ° C. for 7 h. After the reaction was completed, the mixture was filtered, and the filtrate was added to ice water to precipitate solids, which were filtered and vacuum dried to obtain intermediate product 2; Step A5, under nitrogen conditions, 8g of intermediate product 2 and 100mL of dimethylacetamide were added to the reactor and stirred for 15min, 4.5g of pyromellitic dianhydride was added in batches, and the system temperature was controlled to react at 0°C for 2h, and then reacted at room temperature for 6h. After the reaction was completed, vacuum rotary evaporation was performed, and then 90mL of DMF and 30mL of 1-methyl-2-pyrrolidone were added and stirred for 15min, and then the spinning solution was obtained by decompression and filtration. The spinning solution was passed through a spinneret for wet spinning, and the obtained fiber was washed with water, and then placed in a tubular furnace for hot drawing, and finally the fiber was collected to obtain a modified polyimide fiber. During the hot drawing process, the first stretching temperature was 180°C, the stretching ratio was 3, the second stretching temperature was 240°C, the stretching ratio was 3, and the third stretching temperature was 320°C, and the stretching ratio was 1. Example 2

[0018] (1) The flame retardant polyester fiber is prepared by the following steps: The raw materials were weighed by weight, 40 parts of polyester and 12 parts of flame retardant masterbatch (Flame retardant masterbatch 51443 of Shenzhen Jinzhicheng Plastic Technology Co., Ltd.) were blended at 40°C for 60 minutes, and then vacuum dried. 1.5 parts of triallyl isocyanurate were added and blended at 75°C for 1.5 hours to obtain a mixture. The mixture was then melt-extruded through a screw extruder, and the melt was spun and heat-set to obtain flame-retardant polyester fiber.

[0019] (2) The modified polyimide fiber is prepared by the following steps: Step A1, 0.15 mol of tris(hydroxymethyl)aminomethane and 0.2 mol of triethylamine were stirred evenly in 500 mL of dichloromethane, 0.15 mol of diphenyl chlorophosphonate was added dropwise at 0° C. and stirred for 1 hour, and then stirred at room temperature for 12 hours. After the reaction was completed, the mixture was filtered, washed and dried to obtain a phosphorus-containing monomer; Step A2, slowly heating 0.015 mol of phosphorus-containing monomer, 0.03 mol of terminal ester quaternary ammonium salt prepared in Example 1, 0.12 g of dibutyltin dilaurate and 0.001 g of p-hydroxyanisole to 120° C. under stirring, maintaining the top temperature of the fractionation column at 60° C., and keeping the reaction for 3 h. After the reaction is completed, distilling under reduced pressure to obtain a terminal hydroxyl functional monomer; Step A3, add 0.03 mol of p-chloronitrobenzene to 100 mL of DMF and stir to mix evenly, which is recorded as solution A; under nitrogen conditions, add 0.015 mol of terminal hydroxyl functional monomer, 200 mL of DMF and 2.5 g of potassium carbonate into a flask and stir for 10 min, then slowly dropwise add 100 mL of solution A, and increase the system temperature to 100 ° C to react for 5.5 h. After the reaction is completed, slowly add the reaction solution to ice water to precipitate solids, filter and dry, and then perform column chromatography separation, collect the chromatographic liquid and evaporate it under reduced pressure to obtain intermediate 1; Step A4, 10 g of intermediate product 1, 100 mL of 1,4-dioxane and 0.9 g of Raney nickel were added to a reactor and stirred evenly, nitrogen and hydrogen were introduced in sequence, and the system temperature was raised to 80 ° C. for 7 h. After the reaction was completed, the mixture was filtered, and the filtrate was added to ice water to precipitate solids, which were filtered and vacuum dried to obtain intermediate product 2; Step A5, under nitrogen conditions, 10g of intermediate product 2 and 100mL of dimethylacetamide were added to the reactor and stirred for 20min, 5g of pyromellitic anhydride was added in batches, and the system temperature was controlled to react at 0°C for 2h, and then reacted at room temperature for 8h. After the reaction was completed, vacuum rotary evaporation was performed, and then 90mL of DMF and 30mL of 1-methyl-2-pyrrolidone were added and stirred for 20min, and then the decompression and filtration were performed to obtain a spinning solution, and the spinning solution was passed through a spinneret for wet spinning. The obtained fiber was then washed with water and then placed in a tubular furnace for hot drawing. Finally, the fiber was collected to obtain a modified polyimide fiber. During the hot drawing process, the first drawing temperature was 190°C and the drawing ratio was 3, the second drawing temperature was 260°C, the drawing ratio was 3, and the third drawing temperature was 340°C, and the drawing ratio was 1. Example 3

[0020] (1) The flame retardant polyester fiber is prepared by the following steps: The raw materials were weighed by weight, 45 parts of polyester and 15 parts of flame retardant masterbatch (Flame retardant masterbatch 51443 of Shenzhen Jinzhicheng Plastic Technology Co., Ltd.) were blended at 40°C for 60 minutes, and then vacuum dried. Then, 2 parts of triallyl isocyanurate were added and blended at 80°C for 2 hours to obtain a mixture. The mixture was then melt-extruded through a screw extruder, and the melt was spun and heat-set to obtain flame-retardant polyester fiber.

[0021] (2) The modified polyimide fiber is prepared by the following steps: Step A1, 0.2 mol of tris(hydroxymethyl)aminomethane and 0.3 mol of triethylamine are stirred evenly in 500 mL of dichloromethane, 0.2 mol of diphenyl chlorophosphonate is added dropwise at 0-5° C. and stirred for 1 hour, and then stirred at room temperature for 12 hours. After the reaction is completed, the mixture is filtered, washed and dried to obtain a phosphorus-containing monomer; Step A2, slowly heating 0.02 mol of phosphorus-containing monomer, 0.06 mol of terminal ester quaternary ammonium salt prepared in Example 1, 0.16 g of dibutyltin dilaurate and 0.001 g of p-hydroxyanisole to 120° C. under stirring, maintaining the top temperature of the fractionation column at 65° C., and keeping the reaction for 5 h. After the reaction is completed, vacuum distillation is performed to obtain a terminal hydroxyl functional monomer; Step A3, adding 0.04 mol of p-chloronitrobenzene to 100 mL of DMF and stirring to mix evenly, recorded as solution A; under nitrogen conditions, adding 0.02 mol of terminal hydroxyl functional monomer, 200 mL of DMF and 3 g of potassium carbonate into a flask and stirring for 10 min, then slowly adding 100 mL of solution A dropwise, and raising the system temperature to 100 ° C. to react for 6 h. After the reaction is completed, the reaction solution is slowly added to ice water to precipitate solids, filtered and dried, and then separated by column chromatography, and the chromatographic liquid is collected and evaporated under reduced pressure to obtain intermediate 1; Step A4, 12 g of intermediate product 1, 100 mL of 1,4-dioxane and 1.1 g of Raney nickel were added to a reactor and stirred evenly, nitrogen and hydrogen were introduced in sequence, and the system temperature was raised to 80 ° C. for 7 h. After the reaction was completed, the filtrate was filtered, and the filtrate was added to ice water to precipitate solids, which were filtered and vacuum dried to obtain intermediate product 2; Step A5, under nitrogen conditions, 12g of intermediate product 2 and 100mL of dimethylacetamide were added to the reactor and stirred for 25min, 5.5g of pyromellitic dianhydride was added in batches, and the system temperature was controlled to react at 0°C for 2h, and then reacted at room temperature for 10h. After the reaction was completed, vacuum rotary evaporation was performed, and then 90mL of DMF and 30mL of 1-methyl-2-pyrrolidone were added and stirred for 25min, and then the decompression and filtration were performed to obtain a spinning solution, and the spinning solution was passed through a spinneret for wet spinning. The obtained fiber was then washed with water and then placed in a tubular furnace for hot drawing. Finally, the fiber was collected to obtain a modified polyimide fiber. During the hot drawing process, the first drawing temperature was 200°C and the drawing ratio was 3, the second drawing temperature was 280°C, the drawing ratio was 3, and the third drawing temperature was 360°C, and the drawing ratio was 1. Example 4

[0022] A method for preparing flame-retardant and antibacterial chenille yarn comprises the following steps: Two flame-retardant polyester fibers prepared in Example 1 are used as core wires and twisted with a twist of 200 twists / m. The modified polyimide fiber prepared in Example 1 is sandwiched between the two core wires as feather yarn, and the axial density of the feather yarn is 600 yarns / cm, thereby obtaining flame-retardant and antibacterial chenille yarn. Example 5

[0023] A method for preparing flame-retardant and antibacterial chenille yarn comprises the following steps: Two flame-retardant polyester fibers prepared in Example 2 are used as core wires and twisted with a twist of 400 twists / m. The modified polyimide fiber prepared in Example 2 is sandwiched between the two core wires as feather yarn, and the axial density of the feather yarn is 800 yarns / cm, thereby obtaining flame-retardant and antibacterial chenille yarn. Example 6

[0024] A method for preparing flame-retardant and antibacterial chenille yarn comprises the following steps: Two flame-retardant polyester fibers prepared in Example 3 are used as core threads and twisted at a twist of 600 twists / m. The modified polyimide fiber prepared in Example 3 is sandwiched between the two core threads as feather yarn, and the axial density of the feather yarn is 1200 yarns / cm, thereby obtaining flame-retardant and antibacterial chenille yarn.

[0025] Comparative Example 1 This comparative example is a chenille yarn, which is different from Example 6 in that polyester fiber is used instead of the flame-retardant polyester fiber prepared in Example 3, and the rest is the same.

[0026] Comparative Example 2 This comparative example is a chenille yarn, which is different from Example 6 in that polyimide is used instead of the modified polyimide fiber prepared in Example 3, and the rest is the same.

[0027] The chenille yarns prepared in Examples 4-6 and Comparative Examples 1-2 were subjected to performance tests: Flame retardant performance test: Test the limiting oxygen index according to GB / T 2406 standard; Antibacterial performance test: Antibacterial performance was tested according to GB / T 20944.3-2008 standard; the test results are shown in the following table:

[0028] It can be seen from the above table that after the flame retardancy test, the limiting oxygen index of the chenille yarn prepared by the present invention is in the range of 31.2%-32.4%; after the antibacterial performance test, the antibacterial rate of Staphylococcus aureus is in the range of 99.8%-99.9%, and the antibacterial rate of Escherichia coli is in the range of 99.6%-99.7%; the above data show that it has excellent antibacterial and flame retardant properties and can be widely used in textiles such as bedding, carpets, curtains, etc.

[0029] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the scope defined by the concept of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A flame retardant and antibacterial chenille yarn, characterized in that: It comprises a core thread and feather yarn, wherein the core thread is flame-retardant polyester fiber and the feather yarn is modified polyimide fiber; The flame retardant polyester fiber is prepared by the following steps: The raw materials are weighed by weight, 35-45 parts of polyester and 10-15 parts of flame retardant masterbatch are blended at 40°C for 60 minutes, and then vacuum dried. 1-2 parts of cross-linking agent are added and blended at 70-80°C for 1-2 hours to obtain a mixture. The mixture is then melt-extruded through a screw extruder, and the obtained melt is spun and heat-set to obtain flame-retardant polyester fiber.

2. The flame retardant and antibacterial chenille yarn according to claim 1, characterized in that: The modified polyimide fiber is prepared by the following steps: Step A1, tris(hydroxymethyl)aminomethane and triethylamine are stirred evenly in dichloromethane, diphenyl chlorophosphonate is added dropwise at 0-5°C and stirred for 1 hour, and then stirred at room temperature for 12 hours. After the reaction is completed, the mixture is filtered, washed and dried to obtain a phosphorus-containing monomer; Step A2, slowly heating the phosphorus-containing monomer, terminal ester quaternary ammonium salt, dibutyltin dilaurate and p-hydroxyanisole to 120° C. under stirring conditions, and maintaining the top temperature of the fractionation column at 55-65° C., keeping the reaction for 2-5 hours, and after the reaction is completed, performing reduced pressure distillation to obtain a terminal hydroxyl functional monomer; Step A3, adding p-chloronitrobenzene to DMF and stirring to mix evenly, recorded as solution A; under nitrogen conditions, adding terminal hydroxyl functional monomer, DMF and potassium carbonate into a flask and stirring for 10 minutes, then slowly adding solution A dropwise, and raising the system temperature to 100° C. to react for 5-6 hours. After the reaction is completed, slowly adding the reaction solution into ice water to precipitate solids, filtering and drying, and then performing column chromatography separation, collecting the chromatographic solution and performing vacuum rotary evaporation to obtain intermediate product 1; Step A4, add the intermediate product 1, 1,4-dioxane and Raney nickel into a reactor and stir evenly, introduce nitrogen and hydrogen in sequence, and raise the system temperature to 80°C to react for 7 hours. After the reaction is completed, filter, add ice water to the filtrate to precipitate solids, filter and vacuum dry to obtain the intermediate product 2; Step A5, under nitrogen conditions, add the intermediate product 2 and dimethylacetamide to the reactor and stir for 15-25 minutes, add pyromellitic anhydride in batches, and control the system temperature to react at 0°C for 2 hours, and then react at room temperature for 6-10 hours. After the reaction is completed, vacuum evaporation is performed, and then a mixed solution of DMF and 1-methyl-2-pyrrolidone is added and stirred for 15-25 minutes, and then the decompression and filtration are performed to obtain a spinning solution. The spinning solution is passed through a spinneret for wet spinning, and the obtained fiber is washed with water, and then placed in a tubular furnace for hot drawing, and finally the yarn is collected to obtain a modified polyimide fiber.

3. The flame retardant and antibacterial chenille yarn according to claim 2, characterized in that: In step A1, the usage ratio of tris(hydroxymethyl)aminomethane, triethylamine, dichloromethane and diphenyl chlorophosphonate is 0.1-0.2 mol: 0.1-0.3 mol: 500 mL: 0.1-0.2 mol.

4. The flame retardant and antibacterial chenille yarn according to claim 2, characterized in that: In step A2, the usage ratio of the phosphorus-containing monomer, the terminal ester quaternary ammonium salt, dibutyltin dilaurate and p-hydroxyanisole is 0.01-0.02 mol: 0.01-0.06 mol: 0.08-0.16 g: 0.001 g.

5. The flame retardant and antibacterial chenille yarn according to claim 2, characterized in that: In step A3, the usage ratio of terminal hydroxyl functional monomer, DMF, potassium carbonate and solution A is 0.01-0.02 mol: 200 mL: 1.5-3 g: 100 mL, and the usage ratio of p-chloronitrobenzene and DMF in solution A is 0.02-0.04 mol: 100 mL.

6. The flame retardant and antibacterial chenille yarn according to claim 1, characterized in that: In step A4, the usage ratio of the intermediate product 1, 1,4-dioxane and Raney nickel is 8-12 g:100 mL:0.7-1.1 g.

7. The flame retardant and antibacterial chenille yarn according to claim 2, characterized in that: In step A5, the usage ratio of intermediate product 2, dimethylacetamide, pyromellitic anhydride, DMF and 1-methyl-2-pyrrolidone is 8-12 g:100 mL:4.5-5.5 g:90 mL:30 mL.

8. The flame retardant and antibacterial chenille yarn according to claim 2, characterized in that: In the hot stretching process in step A5, the first stretching temperature is 180-200°C, the stretching ratio is 3, the second stretching temperature is 240-280°C, the stretching ratio is 3, and the third stretching temperature is 320-360°C, the stretching ratio is 1.

9. The flame retardant and antibacterial chenille yarn according to claim 2, characterized in that: The terminal ester group quaternary ammonium salt described in step A2 is prepared by the following steps: Add methyl 3-chloropropionate and N, N-dimethylpropylamine into a reactor, then add dichloromethane as solvent, and reflux at 90-100°C for 5-8h. After the reaction is completed, a terminal ester quaternary ammonium salt is obtained. The dosage ratio of methyl 3-chloropropionate, N, N-dimethylpropylamine and dichloromethane is 0.1 mol: 0.11 mol: 20 mL.

10. The method for preparing a flame retardant and antibacterial chenille yarn according to claim 1, characterized in that: The following steps are involved: Two flame-retardant polyester fibers are used as core threads and twisted at a twist of 200-600 twists / meter, and modified polyimide fiber is sandwiched between the two core threads as feather yarn, and the axial density of the feather yarn is 600-1200 yarns / cm, so as to obtain flame-retardant and antibacterial chenille yarn.

Images