Method for preparing flame-retardant and wear-resistant fibers for fireproof clothing using recycled polyester fibers

Abstract

The present invention discloses a method for preparing flame-retardant and wear-resistant fibers for fireproof clothing using recycled polyester fibers, belonging to the technical field of fiber processing, and specifically comprising the following steps: mixing a polyester alcoholysis product, a siloxane-based modifier, a catalyst, and an additive assistant, and carrying out a polycondensation reaction for 3-5 h. After the polyester alcoholysis product is modified by the siloxane-based modifier, it is reinforced and modified with an epoxy-modified filler, and a recycled polyester fiber with a "rigid skeleton + flexible network" is prepared through melt spinning and then hot drawing. Then, surface enhancement protection is carried out with polypyrrole, which not only effectively improves the mechanical strength of the wear-resistant and flame-retardant fibers, but also improves the wear resistance and flame retardancy of the wear-resistant and flame-retardant fibers, making it easier to be applied in special fields such as fireproof clothing.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber processing, and particularly to a method for preparing flame-retardant and wear-resistant fibers for fire-proof clothing using recycled polyester fibers. Background Art

[0002] With the continuous progress of industrial technology and the increasing awareness of safety among people, as an important personal protective equipment, the performance requirements for fire-proof clothing are becoming increasingly strict. Especially in working environments with high temperatures, flammability or potential fire risks, fire-proof clothing not only needs to have excellent flame-retardant performance, but also sufficient wear resistance and comfort to ensure the life safety and working efficiency of the wearer.

[0003] However, the existing recycled polyester fibers are mainly prepared by recycling waste polyester products and reprocessing them into usable fiber materials through a series of treatment processes. Such fibers not only help reduce environmental pollution caused by waste, but also effectively save resources. However, pure recycled polyester fibers still have difficulty meeting the requirements of high-performance fire-proof clothing in terms of flame retardancy and wear resistance. To improve the flame-retardant performance of recycled polyester fibers, flame retardants are usually added during the fiber preparation process, enabling the fibers to quickly play a role when encountering a fire source, forming a protective film to prevent the spread of flames. However, traditional flame retardants have problems such as poor compatibility with the polyester matrix and low flame-retardant efficiency. The large amount of addition and use of flame retardants will cause a decrease in the mechanical strength of recycled polyester fibers. Moreover, polyester fibers are prone to wear under high-temperature and high-friction environments, which also limits their application in special fields such as fire-proof clothing. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing flame-retardant and wear-resistant fibers for fire-proof clothing using recycled polyester fibers, so as to solve the technical problems that the mechanical strength, wear resistance and flame-retardant performance of polyester fibers in the prior art need to be further improved.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing flame-retardant and wear-resistant fibers for fire-proof clothing using recycled polyester fibers, comprising the following steps:

[0006] S1. Mix a polyester alcoholysis product, a siloxane-based modifier, a catalyst I and an additive assistant, and carry out a polycondensation reaction at a temperature of 220 - 230 °C and a negative pressure of 10 - 100 Pa for 3 - 5 h, and discharge the material while it is hot to obtain a composite polyester;

[0007] The synthesis reaction mechanism of the composite polyester is:

[0008] During the reaction, the 1,2-ethylene glycol monoacetate modified on the polyester alcoholysis product and the siloxane-based modifier molecules promotes the transesterification and condensation reactions through Catalyst I, accelerates the formation of the polyester chain, introduces a polysiloxane chain segment into the composite polyester molecular chain, and obtains a composite polyester chain.

[0009] S2. Mix the composite polyester and the epoxy-modified filler, and perform hot drawing after melt spinning to obtain regenerated polyester fibers;

[0010] S3. Deposit and coat polypyrrole on the outside of the regenerated polyester fibers through chemical deposition to obtain flame-retardant and wear-resistant fibers.

[0011] Furthermore, in step S1, the weight ratio of the polyester alcoholysis product, the siloxane-based modifier, Catalyst I, and the additive is 90-100:20-30:2-3:3-5. Catalyst I is antimony trioxide. The additive is composed of a heat stabilizer, a delustering agent, and a lubricant in a weight ratio of 1:3:2. The heat stabilizer is one of phosphite and trimethyl phosphate. The delustering agent is one of magnesium silicate, aluminum silicate, and titanium dioxide. The lubricant is a stearate.

[0012] Furthermore, in step S2, the weight ratio of the composite polyester to the epoxy-modified filler is 100:17-21. The melt spinning temperature is 245-255 °C, the pore diameter of the spinneret is 0.3-0.5 mm, the hot drawing temperature is 160-180 °C, and the hot drawing ratio is 5-6 times.

[0013] Furthermore, the preparation method of the polyester alcoholysis product is as follows: Under an inert gas atmosphere, mix waste polyester powder, ethylene glycol, and Catalyst III. Raise the temperature of the reaction system to 190-195 °C, keep the temperature for reaction for 3-5 h, add activated carbon to the reaction system, keep the temperature for reaction for 80-100 min, and perform post-treatment to obtain the polyester alcoholysis product.

[0014] The synthesis reaction mechanism of the polyester alcoholysis product is as follows:

[0015] The main component of the waste polyester powder is polyethylene terephthalate. When preparing the polyester alcoholysis product, ethylene glycol is used as the alcoholysis agent. Under the action of high temperature and Catalyst III, the ester bonds in the polyester chain are broken to generate bis(2-hydroxyethyl) terephthalate monomers or oligomers. Activated carbon is added during the reaction, which can adsorb impurities and improve the product purity. The reaction system is mixed with water and then cooled to crystallize the alcoholysis product at low temperature, and the polyester alcoholysis product is prepared.

[0016] Further, the dosage ratio of the waste polyester powder, ethylene glycol, catalyst III and activated carbon is 100 g: 200 mL: 1 g: 5 g. The catalyst III is zinc acetate. The post-treatment includes: after the reaction is completed, the temperature of the reaction system is reduced to 150 - 160 °C, and hot filtration is carried out while it is hot. The filtrate and deionized water are mixed at a volume ratio of 1:2, the temperature of the reaction system is reduced to 3 - 8 °C, and it is kept warm and stirred for 60 - 80 min, then filtration is carried out. The filter cake is washed three times with deionized water and then dried by suction. The filter cake is transferred to a drying oven at a temperature of 60 - 70 °C and vacuum dried to constant weight to obtain the polyester alcoholysis product.

[0017] Further, the preparation method of the flame-retardant and wear-resistant fiber is as follows: Mix pyrrole, recycled polyester fiber and deionized water, stir and disperse at room temperature for 30 - 50 min, dropwise add the catalyst solution to the reaction system, keep the temperature and react for 3 - 5 h, and then carry out post-treatment to obtain the flame-retardant and wear-resistant fiber.

[0018] The synthesis reaction mechanism of the flame-retardant and wear-resistant fiber is as follows:

[0019] During the reaction process, ferric ions in the ferric chloride solution catalyze the oxidation of pyrrole monomers to generate pyrrole radical cations. The pyrrole radical cations and other pyrrole monomers undergo a chain polymerization reaction on the surface of the recycled polyester fiber to form polypyrrole coating, and the flame-retardant and wear-resistant fiber is prepared.

[0020] Further, the dosage ratio of the pyrrole, recycled polyester fiber, deionized water and catalyst solution is 1 g: 3 g: 10 mL: 0.5 mL. The catalyst solution is composed of ferric chloride and deionized water at a ratio of 1 g: 10 mL. The post-treatment includes: after the reaction is completed, filtration is carried out. The filter cake is washed 3 times with deionized water and then dried by suction. The filter cake is placed in a drying oven at a temperature of 50 - 60 °C and vacuum dried to constant weight to obtain the flame-retardant and wear-resistant fiber.

[0021] Further, the siloxane-based modifier is processed by the following steps:

[0022] A1. Under an inert gas atmosphere, mix modified DOPO, D4, toluene and catalyst II, raise the temperature of the reaction system to 85 - 95 °C, keep the temperature and react for 2 - 3 h, add a capping agent to the reaction system, keep the temperature and react for 60 - 80 min, and then carry out post-treatment to obtain DOPO-modified polysiloxane;

[0023] A2. Under an inert gas atmosphere, mix DOPO-modified polysiloxane, 2-hydroxyethyl acrylate, toluene and initiator I, raise the temperature of the reaction system to 70 - 80 °C, keep the temperature and react for 4 - 6 h, and then carry out post-treatment to obtain the siloxane-based modifier.

[0024] The synthesis reaction formula of the siloxane-based modifier is as follows:

[0025]

[0026] In the formula

[0027] The synthesis reaction mechanism of the siloxane-based modifier is as follows:

[0028] During the reaction process, under the catalysis of formic acid, octamethylcyclotetrasiloxane (D4) undergoes ring-opening polymerization to generate linear siloxane. At the same time, the siloxane-ethyl bond on the modified DOPO molecule hydrolyzes to form silanol groups, and the silanol groups undergo dehydration condensation with the linear siloxane to generate Si-O-Si, thereby modifying DOPO onto the polysiloxane chain. 1,1,3,3-Tetramethyldisiloxane is used as a capping agent, and after hydrolysis, it reacts with the silanol groups at the end of the polysiloxane chain to generate a hydrosilyl-terminated modification, and the DOPO-modified polysiloxane is prepared;

[0029] The acrylic acid 2-hydroxyethyl ester radical undergoes a radical addition reaction with the silicon hydride on the DOPO-modified polysiloxane chain under the action of initiator I, and a 1,2-ethylene glycol monoacetate modification is formed at the end of the DOPO-modified polysiloxane, and the siloxane-based modifier is prepared.

[0030] Furthermore, in step A1, the dosage ratio of the modified DOPO, D4, toluene, catalyst II, and capping agent is 2 g: 7 g: 30 mL: 1.5 mL: 1 g. The catalyst II is a 30-35 wt% aqueous formic acid solution, and the capping agent is 1,1,3,3-tetramethyldisiloxane. The post-treatment includes: after the reaction is completed, the reaction system is kept at 85-95 °C, and the low-boiling substances are removed by reduced pressure distillation to obtain the DOPO-modified polysiloxane; in step A2, the dosage ratio of the DOPO-modified polysiloxane, acrylic acid 2-hydroxyethyl ester, toluene, and initiator I is 2 g: 1 g: 20 mL: 0.05 g. The initiator I is azobisisobutyronitrile, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is raised to 90 °C, and the low-boiling substances are removed by reduced pressure distillation to obtain the siloxane-based modifier.

[0031] Furthermore, the preparation method of the modified DOPO is as follows: under an inert gas atmosphere, DOPO, diethoxymethylvinylsilane, toluene, and initiator II are mixed, the temperature of the reaction system is raised to 70-80 °C, and the reaction is kept for 4-6 h, followed by post-treatment to obtain the modified DOPO.

[0032] The synthesis reaction formula of the modified DOPO is:

[0033]

[0034] The synthesis reaction mechanism of the modified DOPO is:

[0035] During the reaction process, under the action of initiator II, the vinyl double bond on the diethoxymethylvinylsilane molecule undergoes an addition reaction with the P-H bond in the DOPO molecule, introducing diethoxymethylsilane onto the DOPO molecule to prepare modified DOPO;

[0036] The mass spectrometry analysis data of the modified DOPO are as follows: m / z: 390.14162 (100.0%), 391.14498 (21.6%), 391.14119 (5.1%), 392.13847 (3.3%), 392.14833 (2.2%), 392.14455 (1.1%).

[0037] Furthermore, the dosage ratio of DOPO to diethoxymethylvinylsilane is 1 mol: 1.01 mol, the dosage ratio of DOPO, toluene and initiator II is 1 g: 6 mL: 0.02 g, the initiator II is azobisisobutyronitrile, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is raised to 90 °C, and the low-boiling substances are removed by reduced pressure distillation to obtain modified DOPO.

[0038] Furthermore, the preparation method of the epoxy-modified filler is: mixing nano-aluminum oxide, graphene, KH-560 and ethanol, ultrasonically dispersing for 30 - 50 min, raising the temperature of the reaction system to 50 - 60 °C, adding sodium hydroxide solution to the reaction system, keeping the temperature for reaction for 60 - 80 min, and performing post-treatment to obtain the epoxy-modified filler.

[0039] The synthesis reaction mechanism of the epoxy-modified filler is:

[0040] During the reaction process, the trimethoxysilyl group of KH-560 hydrolyzes under alkaline conditions to generate silanol, and the silanol reacts with the surface active groups of nano-aluminum oxide or graphene particles to form siloxane bonds, forming KH-560 modification on the nano-aluminum oxide and graphene particles to prepare the epoxy-modified filler.

[0041] Furthermore, the dosage ratio of the nano-aluminum oxide, graphene, KH-560, ethanol and sodium hydroxide solution is 5 g: 1 g: 2 g: 50 mL: 8 mL, the concentration of the sodium hydroxide solution is 0.3 - 0.5 mol / L, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, suction filtration is performed, the filter cake is washed with purified water until neutral and then dried by suction, the filter cake is transferred to an oven at 60 - 70 °C, and vacuum dried to constant weight to obtain the epoxy-modified filler.

[0042] The present invention has the following beneficial effects:

[0043] 1. The flame-retardant and wear-resistant fiber for fireproof clothing of the present invention is prepared by modifying the polyester alcoholysis product with a siloxane-based modifier to prepare a composite polyester modified with polysiloxane, and then enhancing and modifying the composite polyester with an epoxy-modified filler. After melt spinning, hot drawing is carried out to increase the orientation degree of the polyester molecular chain, improve the crystallinity and axial strength, and prepare a regenerated polyester fiber with a "rigid skeleton + flexible network" structure. By coating and modifying polypyrrole on the outside of the regenerated polyester fiber, a "surface enhancement + matrix protection" structure is formed, thereby improving the breaking strength and wear resistance of the wear-resistant and flame-retardant fiber. Moreover, polypyrrole carbonizes at high temperature to form a dense carbon layer, blocking the diffusion of heat and oxygen and enhancing the flame-retardant effect in the condensed phase. Its cooperation with the regenerated polyester fiber further improves its flame-retardant performance.

[0044] 2. The flame-retardant and wear-resistant fiber for fireproof clothing of the present invention epoxidizes and modifies the inorganic filler with KH-560, making the inorganic filler more easily and uniformly dispersed in the composite polyester. Under high-temperature action, the epoxy groups on the epoxy-modified filler molecules undergo ring-opening condensation with the active functional groups on the composite polyester molecules, increasing the crosslinking degree of the molecules and improving the hardness and wear resistance of the regenerated polyester fiber. By introducing a polysilane block into the regenerated polyester fiber, flexibility is imparted to the polyester chain segments, avoiding brittle fracture of the fiber caused by the crosslinking and bonding of the inorganic filler, and improving the mechanical strength of the material. Moreover, DOPO in the siloxane modifier is chemically bonded with the siloxane to form a dense silicon-phosphorus synergistic carbon layer during combustion, blocking oxygen and heat, and improving the thermal stability and flame-retardant performance of the regenerated polyester fiber. Nano-aluminum oxide and graphene with a two-dimensional sheet structure form a dense physical barrier layer at high temperature, delaying the diffusion of heat and oxygen, inhibiting the thermal decomposition of the matrix by physically blocking the heat transfer, and further improving the heat resistance and flame-retardant performance of the regenerated polyester fiber. The polypyrrole coating can further block heat and oxygen, prevent the fiber matrix from being directly exposed to a high-temperature environment, enhance the flame-retardant and high-temperature resistance performance of the fiber material, and reduce fiber damage during friction, further improving the anti-wear ability of the regenerated polyester fiber. Detailed implementation manners

[0045] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0046] In this application, the waste polyester powder is waste PET powder with a particle size of 100 - 300 μm;

[0047] In this application, DOPO is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and its CAS number is 35948-25-5;

[0048] In this application, D4 is octamethylcyclotetrasiloxane, and its CAS number is 556-67-2;

[0049] In this application, the particle size of graphene is 0.8 - 80 nm;

[0050] In this application, the particle size of nano-aluminum oxide is 10 - 15 nm;

[0051] In this application, KH-560 is γ-glycidoxypropyltrimethoxysilane, and its CAS number is 2530-83-8.

[0052] Example 1

[0053] This example provides a method for preparing flame-retardant and wear-resistant fibers for fireproof clothing using recycled polyester fibers, including the following steps:

[0054] Step 1: Prepare polyester alcoholysis product

[0055] Weigh: 500 g of waste polyester powder, 1000 mL of ethylene glycol, and 5 g of zinc acetate, add them to a reaction kettle under nitrogen protection and stir. After the reaction kettle is sealed, the temperature is raised to 190 °C, and the reaction is carried out for 3 h. Add 25 g of activated carbon to the reaction system, keep the temperature for 80 min, then lower the temperature of the reaction kettle to 150 °C, and filter while it is hot. The filtrate and deionized water are mixed in another reaction kettle at a volume ratio of 1:2. Lower the temperature of the reaction kettle to 3 °C, keep stirring for 60 min, filter, wash the filter cake three times with deionized water and then drain it. Transfer the filter cake to a drying oven at 60 °C and vacuum dry it to constant weight to obtain the polyester alcoholysis product.

[0056] Step 2: Prepare silane-based modifier

[0057] Weigh: 43.2 g of DOPO, 32.4 g of diethoxymethylvinylsilane, 259.2 mL of toluene, and 1.3 g of azobisisobutyronitrile, add them to a three-necked flask under nitrogen protection and stir. Raise the temperature of the three-necked flask to 70 °C and keep the reaction for 4 h. Then raise the temperature of the three-necked flask to 90 °C and distill off the low-boiling substances under reduced pressure to obtain modified DOPO;

[0058] Weigh: 40 g of modified DOPO, 140 g of D4, 600 mL of toluene, and 30 mL of 30 wt% formic acid aqueous solution, add them to a three-necked flask under nitrogen protection and stir. Raise the temperature of the three-necked flask to 85 °C and keep the reaction for 2 h. Add 20 g of 1,1,3,3-tetramethyldisiloxane to the three-necked flask and keep the reaction for 60 min. Keep the temperature of the three-necked flask at 85 °C and distill off the low-boiling substances under reduced pressure to obtain DOPO-modified polysiloxane;

[0059] Weigh: 160 g of DOPO-modified polysiloxane, 80 g of hydroxyethyl acrylate, 1600 mL of toluene and 4 g of azobisisobutyronitrile are added to a three-necked flask protected by nitrogen and stirred. The temperature of the three-necked flask is raised to 70 °C, and the reaction is carried out under insulation for 4 h. Then the temperature of the three-necked flask is raised to 90 °C, and the low-boiling substances are removed by vacuum distillation to obtain a siloxane-based modifier.

[0060] Step 3: Prepare composite polyester

[0061] Mix phosphite, magnesium silicate and calcium stearate in a weight ratio of 1:3:2 to obtain an additive assistant for standby.

[0062] Weigh by weight: 90 parts of polyester alcoholysis product, 20 parts of siloxane-based modifier, 2 parts of antimony trioxide and 3 parts of additive assistant are added to a polycondensation reactor and stirred. The temperature of the polycondensation reactor is raised to 220 °C, and the negative pressure is pumped to 10 Pa. The polycondensation reaction is carried out for 3 h, and the product is discharged while it is hot to obtain composite polyester.

[0063] Step 4: Prepare recycled polyester fibers

[0064] Weigh: 50 g of nano-aluminum oxide, 10 g of graphene, 20 g of KH-560 and 500 mL of absolute ethanol are added to a three-necked flask and ultrasonically dispersed at room temperature for 30 min. The three-necked flask is fixed on an iron stand with mechanical stirring. The temperature of the three-necked flask is raised to 50 °C, and 80 mL of 0.3 mol / L sodium hydroxide solution is added to the three-necked flask. The reaction is carried out under insulation for 60 min. Then the temperature of the three-necked flask is lowered to room temperature, and filtration is carried out. The filter cake is washed with purified water until neutral and then dried by suction. The filter cake is transferred to a drying oven at 60 °C and vacuum dried to constant weight to obtain epoxy-modified filler.

[0065] Weigh by weight: 100 parts of composite polyester and 17 parts of epoxy-modified filler are mixed and then added to a melt spinning machine at 245 °C with a spinneret hole diameter of 0.3 mm for melt spinning. Then the spun fiber is subjected to hot drawing at 5 times the length in an environment at 160 °C to obtain recycled polyester fibers.

[0066] Step 5: Prepare wear-resistant and flame-retardant fibers

[0067] Mix ferric chloride and deionized water in a ratio of 1 g:10 mL and stir until the system is dissolved to obtain a catalyst solution for standby.

[0068] Weigh: 50 g of pyrrole, 150 g of recycled polyester fibers and 500 mL of deionized water are added to a beaker and stirred. Stir and disperse at room temperature for 30 min. Then 25 mL of the catalyst solution is added dropwise to the beaker. The reaction is carried out under insulation for 3 h. Then filtration is carried out. The filter cake is washed 3 times with deionized water and then dried by suction. The filter cake is placed in a drying oven at 50 °C and vacuum dried to constant weight to obtain flame-retardant and wear-resistant fibers.

[0069] Example 2

[0070] This example provides a method for preparing flame-retardant and wear-resistant fibers for fire-proof clothing using recycled polyester fibers, including the following steps:

[0071] Step 1: Prepare polyester alcoholysis product

[0072] Weigh: 500 g of waste polyester powder, 1000 mL of ethylene glycol, and 5 g of zinc acetate, add them to a reaction kettle protected by nitrogen and stir. After the reaction kettle is sealed, the temperature is raised to 193 °C, and the reaction is carried out for 4 h while maintaining the temperature. Add 25 g of activated carbon to the reaction system, and keep the reaction for 90 min. Then, lower the temperature of the reaction kettle to 155 °C, and filter while it is hot. Mix the filtrate and deionized water in a volume ratio of 1:2 in another reaction kettle, lower the temperature of the reaction kettle to 5 °C, keep stirring for 70 min, filter, wash the filter cake three times with deionized water and then drain it. Transfer the filter cake to a drying oven at 65 °C and vacuum dry it to constant weight to obtain the polyester alcoholysis product.

[0073] Step 2: Prepare silane-based modifier

[0074] Weigh: 43.2 g of DOPO, 32.4 g of diethoxymethylvinylsilane, 259.2 mL of toluene, and 1.3 g of azobisisobutyronitrile, add them to a three-necked flask protected by nitrogen and stir. Raise the temperature of the three-necked flask to 75 °C and keep the reaction for 5 h. Then, raise the temperature of the three-necked flask to 90 °C and distill off the low-boiling substances under reduced pressure to obtain modified DOPO;

[0075] Weigh: 40 g of modified DOPO, 140 g of D4, 600 mL of toluene, and 30 mL of 33 wt% formic acid aqueous solution, add them to a three-necked flask protected by nitrogen and stir. Raise the temperature of the three-necked flask to 90 °C and keep the reaction for 2.5 h. Add 20 g of 1,1,3,3-tetramethyldisiloxane to the three-necked flask and keep the reaction for 70 min. Keep the temperature of the three-necked flask at 90 °C and distill off the low-boiling substances under reduced pressure to obtain DOPO-modified polysiloxane;

[0076] Weigh: 160 g of DOPO-modified polysiloxane, 80 g of hydroxyethyl acrylate, 1600 mL of toluene, and 4 g of azobisisobutyronitrile, add them to a three-necked flask protected by nitrogen and stir. Raise the temperature of the three-necked flask to 75 °C and keep the reaction for 5 h. Then, raise the temperature of the three-necked flask to 90 °C and distill off the low-boiling substances under reduced pressure to obtain the siloxane-based modifier.

[0077] Step 3: Prepare composite polyester

[0078] Mix trimethyl phosphate, aluminum silicate, and magnesium stearate in a weight ratio of 1:3:2 to obtain an additive assistant for standby;

[0079] Weigh by parts by weight: 95 parts of polyol alcoholysis product, 25 parts of silicone - alkane - based modifier, 2.5 parts of antimony trioxide, and 4 parts of additive assistant, add them to a polycondensation reactor and stir. Raise the temperature of the polycondensation reactor to 225 °C, evacuate to a negative pressure of 50 Pa, carry out polycondensation reaction for 4 h, and discharge the material while it is hot to obtain composite polyester.

[0080] Step Four: Prepare recycled polyester fibers

[0081] Weigh: 50 g of nano - alumina, 10 g of graphene, 20 g of KH - 560, and 500 mL of absolute ethanol, add them to a three - necked flask, ultrasonically disperse at room temperature for 40 min. Fix the three - necked flask on an iron stand with mechanical stirring, raise the temperature of the three - necked flask to 55 °C, add 80 mL of 0.4 mol / L sodium hydroxide solution to the three - necked flask, keep the temperature for reaction for 70 min, lower the temperature of the three - necked flask to room temperature, carry out suction filtration, wash the filter cake with purified water until neutral and then drain it, transfer the filter cake to a drying oven at 65 °C, and vacuum - dry to constant weight to obtain epoxy - modified filler.

[0082] Weigh by parts by weight: 100 parts of composite polyester and 19 parts of epoxy - modified filler, mix them and add them to a melt - spinning machine with a temperature of 250 °C and a spinneret hole diameter of 0.4 mm for melt - spinning, and then carry out hot drawing with a draw ratio of 5.5 times the length in an environment at 170 °C to obtain recycled polyester fibers.

[0083] Step Five: Prepare wear - resistant and flame - retardant fibers

[0084] Mix ferric chloride and deionized water at a ratio of 1 g:10 mL, stir until the system is dissolved to obtain a catalyst solution for standby.

[0085] Weigh: 50 g of pyrrole, 150 g of recycled polyester fibers, and 500 mL of deionized water, add them to a beaker and stir, stir and disperse at room temperature for 40 min, drop 25 mL of the catalyst solution into the beaker, keep the temperature for reaction for 4 h, filter, wash the filter cake with deionized water 3 times and then drain it, place the filter cake in a drying oven at 55 °C, and vacuum - dry to constant weight to obtain flame - retardant and wear - resistant fibers.

[0086] Example 3

[0087] This example provides a method for preparing flame - retardant and wear - resistant fibers for fire - proof clothing using recycled polyester fibers, including the following steps:

[0088] Step One: Prepare polyol alcoholysis product

[0089] Weigh: 500 g of waste polyester powder, 1000 mL of ethylene glycol, and 5 g of zinc acetate, add them to a reaction kettle under nitrogen protection and stir. After the reaction kettle is sealed, the temperature is raised to 195 °C, and keep the temperature for 5 h. Add 25 g of activated carbon to the reaction system, keep the temperature for 100 min, then lower the temperature of the reaction kettle to 160 °C, and filter while it is hot. Mix the filtrate and deionized water in a volume ratio of 1:2 in another reaction kettle, lower the temperature of the reaction kettle to 8 °C, keep the temperature and stir for 80 min, then filter. Wash the filter cake three times with deionized water and then drain it. Transfer the filter cake to a drying oven at 70 °C and vacuum dry it to constant weight to obtain the polyester alcoholysis product.

[0090] Step 2: Prepare the silyl modifier

[0091] Weigh: 43.2 g of DOPO, 32.4 g of diethoxymethylvinylsilane, 259.2 mL of toluene, and 1.3 g of azobisisobutyronitrile, add them to a three-necked flask under nitrogen protection and stir. Raise the temperature of the three-necked flask to 80 °C, keep the temperature for 6 h, then raise the temperature of the three-necked flask to 90 °C, and distill off the low-boiling substances under reduced pressure to obtain the modified DOPO.

[0092] Weigh: 40 g of modified DOPO, 140 g of D4, 600 mL of toluene, and 30 mL of 35 wt% formic acid aqueous solution, add them to a three-necked flask under nitrogen protection and stir. Raise the temperature of the three-necked flask to 95 °C, keep the temperature for 3 h, add 20 g of 1,1,3,3-tetramethyldisiloxane to the three-necked flask, keep the temperature for 80 min, keep the temperature of the three-necked flask at 95 °C, and distill off the low-boiling substances under reduced pressure to obtain the DOPO-modified polysiloxane.

[0093] Weigh: 160 g of DOPO-modified polysiloxane, 80 g of hydroxyethyl acrylate, 1600 mL of toluene, and 4 g of azobisisobutyronitrile, add them to a three-necked flask under nitrogen protection and stir. Raise the temperature of the three-necked flask to 80 °C, keep the temperature for 6 h, then raise the temperature of the three-necked flask to 90 °C, and distill off the low-boiling substances under reduced pressure to obtain the silyl group modifier.

[0094] Step 3: Prepare the composite polyester

[0095] Mix phosphite, nano-titanium dioxide, and zinc stearate in a weight ratio of 1:3:2 to obtain the additive, and set it aside.

[0096] Weigh by weight: 100 parts of polyester alcoholysis product, 30 parts of silyl group modifier, 3 parts of antimony trioxide, and 5 parts of additive, add them to a polycondensation reaction kettle and stir. Raise the temperature of the polycondensation reaction kettle to 230 °C, draw a negative pressure until the negative pressure is 100 Pa, and carry out polycondensation reaction for 5 h, then discharge while it is hot to obtain the composite polyester.

[0097] Step 4: Prepare the recycled polyester fiber

[0098] Weigh: Add 50 g of nano-aluminum oxide, 10 g of graphene, 20 g of KH-560, and 500 mL of absolute ethanol into a three-necked flask, and ultrasonically disperse for 50 min at room temperature. Fix the three-necked flask on an iron stand with mechanical stirring, raise the temperature of the three-necked flask to 60 °C, add 80 mL of 0.5 mol / L sodium hydroxide solution to the three-necked flask, keep the temperature for reaction for 80 min, lower the temperature of the three-necked flask to room temperature, filter by suction, wash the filter cake with purified water until neutral and then drain it by suction. Transfer the filter cake to a drying oven at 70 °C and vacuum dry to constant weight to obtain epoxy-modified filler;

[0099] Weigh by weight: Take 100 parts of composite polyester and 21 parts of epoxy-modified filler, mix them and add them to a melt spinning machine at a temperature of 255 °C and a spinneret hole diameter of 0.5 mm for melt spinning. Then, perform hot drawing with a 6-fold length on the spun yarn in an environment at a temperature of 180 °C to obtain regenerated polyester fibers.

[0100] Step Five: Prepare wear-resistant and flame-retardant fibers

[0101] Mix ferric chloride and deionized water at a ratio of 1 g:10 mL, stir until the system dissolves to obtain a catalyst solution for standby;

[0102] Weigh: Add 50 g of pyrrole, 150 g of regenerated polyester fibers, and 500 mL of deionized water to a beaker and stir. Stir and disperse at room temperature for 50 min. Drop 25 mL of the catalyst solution into the beaker, keep the temperature for reaction for 5 h, filter, wash the filter cake with deionized water 3 times and then drain it by suction. Place the filter cake in a drying oven at 60 °C and vacuum dry to constant weight to obtain flame-retardant and wear-resistant fibers.

[0103] Comparative Example 1

[0104] The difference between this comparative example and Example 3 is that modified DOPO is not added to the DOPO-modified polysiloxane in Step Two.

[0105] Comparative Example 2

[0106] The difference between this comparative example and Example 3 is that graphene is not added in Step Four.

[0107] Comparative Example 3

[0108] The difference between this comparative example and Example 3 is that in Step Four, a mixture composed of nano-aluminum oxide and graphene at a weight ratio of 5:1 is used to replace the epoxy-modified filler in the regenerated polyester fibers.

[0109] Comparative Example 4

[0110] The difference between this comparative example and Example 3 is that Step Five is cancelled, and the regenerated polyester fibers in Step Four are used to replace the flame-retardant and wear-resistant fibers in Step Five.

[0111] Performance Test:

[0112] The flame-retardant and wear-resistant fibers prepared in Examples 1-3 and Comparative Examples 1-4 were made into test specimens by plain weave method;

[0113] Referring to the standard GB / T 21196.3-2007 "Textiles - Determination of Martindale abrasion resistance of fabrics - Part 3: Determination of mass loss", the mass loss rate of the test specimens prepared in Examples 1-3 and Comparative Examples 1-4 was determined;

[0114] Referring to the standard FZ / T 52026-2012 "Recycled flame-retardant polyester staple fiber", the breaking strength, breaking elongation and oxygen index of the wear-resistant and flame-retardant fibers prepared in Examples 1-3 and Comparative Examples 1-4 were determined. The specific test results are shown in Table 1 below.

[0115] Table 1 - Performance test data table of specimens

[0116]

[0117] Data Analysis:

[0118] By comparing and analyzing the data in Table 1 above, the breaking strength of the flame-retardant and wear-resistant fibers prepared by the present invention reaches 8.6 cN / dtex, the breaking elongation reaches 24.3%, the oxygen index reaches 32%, and the wear resistance index reaches 2.425×10 4 times / mg. All the performance test data are better than those of the comparative examples. The present invention modifies the polyester alcoholysis product with a siloxane-based modifier to prepare a composite polyester, and then enhances and modifies the composite polyester with an epoxy-modified filler. After melt spinning, hot drawing is carried out to prepare recycled polyester fibers, and then polypyrrole coating is carried out, which not only effectively improves the mechanical strength of the wear-resistant and flame-retardant fibers, but also improves the wear resistance and flame retardancy of the wear-resistant and flame-retardant fibers.

[0119] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A method for preparing flame retardant and wear-resistant fibers for fireproof clothing using regenerated polyester fibers, characterized in that: The following steps are involved: S1, mixing the polyester alcoholysis product, the siloxane modifier, the catalyst I and the additive, carrying out polycondensation reaction for 3-5 hours at a temperature of 220-230° C. and a negative pressure of 10-100 Pa, and discharging the material while hot to obtain a composite polyester; S2, mixing the composite polyester and the epoxy modified filler, melt spinning and then heat drawing to obtain the regenerated polyester fiber; S3, depositing and coating polypyrrole on the outside of the regenerated polyester fiber through chemical deposition to obtain a flame retardant and wear-resistant fiber; The siloxane-based modifier is processed by the following steps: A1. In an inert gas atmosphere, the modified DOPO, D4, toluene and catalyst II are mixed, the temperature of the reaction system is raised to 85-95°C, and the reaction is kept warm for 2-3 hours. A capping agent is added to the reaction system, and the reaction is kept warm for 60-80 minutes. After post-treatment, DOPO-modified polysiloxane is obtained; A2. In an inert gas atmosphere, DOPO-modified polysiloxane, hydroxyethyl acrylate, toluene and initiator I are mixed, the temperature of the reaction system is raised to 70-80° C., the reaction is kept warm for 4-6 hours, and post-processed to obtain a siloxane-based modifier.

2. The method for preparing flame retardant and wear resistant fiber for fire retardant clothing using regenerated polyester fiber according to claim 1, characterized in that: In step S1, the weight ratio of the polyester alcoholysis product, the siloxane modifier, the catalyst I and the additive is 90-100:20-30:2-3:3-5, the catalyst I is antimony trioxide, the additive is composed of a heat stabilizer, a matting agent and a lubricant in a weight ratio of 1:3:2, the heat stabilizer is one of phosphite and trimethyl phosphate, the matting agent is one of magnesium silicate, aluminum silicate and titanium dioxide, and the lubricant is stearate; in step S2, the weight ratio of the composite polyester and the epoxy modified filler is 100:17-21, the melt spinning temperature is 245-255°C, the pore size of the spinneret hole is 0.3-0.5mm, the hot drawing temperature is 160-180°C, and the hot drawing ratio is 5-6 times.

3. The method for preparing flame retardant and wear resistant fiber for fire retardant clothing by using regenerated polyester fiber according to claim 1, characterized in that: The preparation method of the flame retardant and wear resistant fiber comprises: mixing pyrrole, regenerated polyester fiber and deionized water, stirring and dispersing for 30-50 minutes at room temperature, dropping a catalyst solution into the reaction system, keeping the temperature for reaction for 3-5 hours, and post-treating to obtain the flame retardant and wear resistant fiber.

4. The method for preparing flame retardant and wear resistant fiber for fireproof clothing using regenerated polyester fiber according to claim 3, characterized in that: The dosage ratio of the pyrrole, the regenerated polyester fiber, the deionized water and the catalyst solution is 1g:3g:10mL:0.5mL, and the catalyst solution is composed of ferric chloride and deionized water in a ratio of 1g:10mL.

5. The method for preparing flame retardant and wear resistant fiber for fireproof clothing using regenerated polyester fiber according to claim 1, characterized in that: In step A1, the amount ratio of the modified DOPO, D4, toluene, catalyst II and capping agent is 2g:7g:30mL:1.5mL:1g, the catalyst II is a 30-35wt% formic acid aqueous solution, and the capping agent is 1,1,3,3-tetramethyldisiloxane; in step A2, the amount ratio of the DOPO modified polysiloxane, hydroxyethyl acrylate, toluene and initiator I is 2g:1g:20mL:0.05g, and the initiator I is azobisisobutyronitrile.

6. The method for preparing flame retardant and wear resistant fiber for fireproof clothing using regenerated polyester fiber according to claim 1, characterized in that: The preparation method of modified DOPO is as follows: under an inert gas atmosphere, DOPO, diethoxymethylvinylsilane, toluene and initiator II are mixed, the temperature of the reaction system is increased to 70-80° C., the reaction is kept warm for 4-6 hours, and post-processed to obtain modified DOPO.

7. The method for preparing flame retardant and wear resistant fiber for fireproof clothing using regenerated polyester fiber according to claim 6, characterized in that: The usage ratio of DOPO and diethoxymethylvinylsilane is 1 mol: 1.01 mol, the usage ratio of DOPO, toluene and initiator II is 1 g:6 mL:0.02 g, and the initiator II is azobisisobutyronitrile.

8. The method for preparing flame retardant and wear resistant fiber for fireproof clothing using regenerated polyester fiber according to claim 1, characterized in that: The preparation method of the epoxy modified filler is as follows: nano-alumina, graphene, KH-560 and ethanol are mixed, ultrasonically dispersed for 30-50 minutes, the temperature of the reaction system is increased to 50-60°C, sodium hydroxide solution is added to the reaction system, the reaction is kept warm for 60-80 minutes, and post-processed to obtain the epoxy modified filler.

9. The method for preparing flame retardant and wear resistant fiber for fireproof clothing using regenerated polyester fiber according to claim 8, characterized in that: The dosage ratio of the nano-alumina, graphene, KH-560, ethanol and sodium hydroxide solution is 5g:1g:2g:50mL:8mL, and the concentration of the sodium hydroxide solution is 0.3-0.5mol / L.

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