Method for polyester regeneration to produce high-elasticity polyester fiber fabric

Abstract

This invention discloses a method for preparing high-elasticity polyester fiber fabric from recycled polyester, belonging to the field of fiber fabric preparation technology. It addresses the technical problem that the toughness and strength of polyester fiber fabrics in existing technologies need further improvement. Specifically, the method includes the following steps: adding modified polyester, a modified toughening agent, and auxiliary additives to a twin-screw extruder, followed by melt spinning to obtain modified polyester fibers. This invention effectively improves the toughness and elasticity of polyester through catalytic recycling, copolymerization modification, and toughening enhancement. Further, through melt spinning and weaving processes, polyester fiber fabric is obtained, which not only improves the toughness and strength of the fiber fabric but also enhances its abrasion resistance.

Description

Technical Field

[0001] This invention relates to the field of fiber fabric preparation technology, and specifically to a method for preparing high-elasticity polyester fiber fabric by polyester recycling. Background Technology

[0002] With the development of sustainable textile industry, the recycling and reuse of waste polyester (PET) has become an important direction for the polyester fiber industry. Recycled polyester fiber (rPET) fabric has excellent dimensional stability and heat resistance, but its toughness, breaking strength and abrasion resistance are generally lower than those of virgin polyester fiber. In order to improve the mechanical properties and performance of recycled polyester, researchers have proposed a variety of modification technologies, including copolymerization modification, blending toughening, filler reinforcement and grafting chain extension reaction. These technologies can improve the molecular weight and mechanical strength of recycled polyester to a certain extent, so that it exhibits better processability and stability in spinning and weaving.

[0003] In existing technologies, there are still shortcomings in the modification of recycled polyester. Reinforcing polyester systems through copolymerization or fillers often leads to a decrease in the regularity of polyester chains and a slower crystallization rate, which in turn affects fiber orientation and crystallinity, resulting in limited strength improvement. Furthermore, the interfacial compatibility between different phases in the blending toughening method is poor, and phase separation interfaces are easily formed, resulting in large dispersion of mechanical properties. In addition, recycled PET itself has problems with molecular chain breakage and end group oxidation, resulting in a wide molecular weight distribution and poor chain segment integrity, making it difficult for traditional modification systems to simultaneously achieve high strength, high elasticity, and wear resistance.

[0004] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing high-elasticity polyester fiber fabrics by polyester recycling, which solves the technical problem that the toughness and strength of polyester fiber fabrics need to be further improved in the prior art.

[0006] The objective of this invention can be achieved through the following technical solution: a method for preparing high-elasticity polyester fiber fabric by polyester recycling, comprising the following steps:

[0007] S1. Place waste polyester fiber, deionized water and modified catalyst in a high-pressure reactor at a temperature of 195-205℃ and keep it at the temperature for 2-3 hours. Then, after processing, regenerated terephthalic acid is obtained.

[0008] The reaction principle for the preparation of regenerated terephthalic acid is as follows:

[0009] During the reaction, under high pressure conditions of 195-205℃, polyethylene terephthalate, the main component of waste polyester fiber, reacts with water, and the ester bonds break to generate terephthalic acid and ethylene glycol. The added modified catalyst is sulfonated cross-linked polystyrene-type strong acid resin, whose surface-fixed -SO3H groups can provide a large number of protons to catalyze the nucleophilic addition-elimination reaction of the ester bonds. The protonated carbonyl carbon promotes the breaking of ester bonds. During the reaction, water acts as both a reactant and a dispersion medium, continuously precipitating the generated terephthalic acid and driving the equilibrium towards hydrolysis. Finally, high-purity recycled terephthalic acid can be obtained after cooling, filtration, and washing.

[0010] S2. Recycled terephthalic acid, 2,2-dimethyl-1,3-propanediol, 2,6-naphthalenedicarboxylic acid, ethylene glycol, antimony glycolate, triphenyl phosphite, and tetrabutyl titanate are placed in a high-pressure reactor under nitrogen atmosphere. The reaction system is evacuated to a vacuum pressure of -0.1 MPa. The high-pressure reactor is heated to 230-250℃ and kept at this temperature for 2-4 hours. Then, the high-pressure reactor is heated to 265-285℃ and kept at this temperature for 0.5-1 hour to obtain modified polyester.

[0011] The reaction principle for the preparation of modified polyester is as follows:

[0012] During the reaction, at a temperature of 230-250℃, regenerated terephthalic acid, ethylene glycol, 2,2-dimethyl-1,3-propanediol, and 2,6-naphthalenedicarboxylic acid undergo esterification to generate oligomeric intermediates. Tetrabutyl titanate provides strong Lewis acid sites, accelerating the early esterification and exchange reactions. Subsequently, the autoclave is heated to 265-285℃ to enter the melt polycondensation stage. The terminal hydroxyl and terminal carboxyl groups of the intermediates condense and ethylene glycol is continuously removed, causing the molecular weight to increase rapidly. At this time, antimony glycol is used as the main catalyst to promote ester exchange and polycondensation. Triphenyl phosphite acts as a phosphate ester stabilizer, complexing and modulating the activity of titanium, inhibiting thermo-oxidative discoloration and excessive end-group growth. Nitrogen is used throughout the process to remove oxygen and avoid ethylene glycol oxidation, ultimately yielding modified polyester.

[0013] S3. Modified polyester, modified toughening agent and auxiliary additives are added to a twin-screw extruder and melt-spun to obtain modified polyester fiber;

[0014] S4. The modified polyester fiber is spun to obtain polyester fiber fabric.

[0015] Further, in step S1, the ratio of waste polyester fiber, deionized water and modified catalyst is 8-10g:80-100mL:0.05-0.1g. The post-treatment step includes: after the reaction is completed, wait for the reaction system to cool to room temperature, add 10-15mL of 0.5-1mol / L sodium hydroxide aqueous solution to the reaction solution, stir for 0.5-1h, filter, add 0.5-1mol / L hydrochloric acid aqueous solution to the filtrate until no more precipitate is precipitated, filter, transfer the filter cake to an oven at 50-60℃, dry to constant weight, and obtain regenerated terephthalic acid;

[0016] Further, in step S2, the weight ratio of the regenerated terephthalic acid, 2,2-dimethyl-1,3-propanediol, 2,6-naphthalenedicarboxylic acid, ethylene glycol, antimony glycolate, triphenyl phosphite, and tetrabutyl titanate is 7-10:2-4:4-6:6-8:0.004-0.006:0.002-0.004:0.01-0.03;

[0017] Further, in step S3, the weight ratio of the modified polyester, the modified toughening agent, and the auxiliary additives is 60-80:10-12:1-3. The auxiliary additives are composed of plasticizer, antistatic agent, and lubricant in a mass ratio of 4:1:3. The plasticizer is one or more of dioctyl phthalate, dibutyl phthalate, and diisononyl phthalate. The antistatic agent is one or more of polyvinyl alcohol, amide phosphate, and tricresyl phosphate. The lubricant is one or more of stearic acid, oleic acid, and fatty acid amide.

[0018] The melt spinning process includes: filtering and homogenizing the melt at the spinning assembly, extruding it through a spinneret, and then cooling and solidifying it in a side-blowing chamber to obtain modified polyester fibers, wherein the spinneret is one or more of the Y-shaped and cross-shaped types.

[0019] The temperatures of the eight temperature zones of the twin-screw extruder from the feed inlet to the discharge outlet are 240℃, 240℃, 250℃, 250℃, 265℃, 265℃, 280℃, and 280℃ respectively. The main engine speed of the twin-screw extruder is 120-160 rpm, and the pressure is 80-120 bar.

[0020] Furthermore, in step S4, the preparation method of the polyester fiber fabric is as follows: after the modified polyester fiber is dried, it is oiled, stretched, and wound into a yarn bobbin at high speed. Finally, it is graded, inspected, and packaged to obtain the modified polyester yarn. After the modified polyester yarn is warped and sized, it is woven into a greige fabric using a machine weaving process. The greige fabric is then boiled, dyed, set, and finished to obtain the modified polyester fiber fabric.

[0021] Furthermore, the modified catalyst is prepared by the following steps:

[0022] A1. Place polyvinyl alcohol and deionized water in a reaction vessel, heat the reaction vessel to 50-60℃, stir for 15-30 min, add styrene, divinylbenzene and benzoyl peroxide, heat the reaction vessel to 65-75℃, keep the reaction for 4-6 h, and then process to obtain the modified catalyst precursor.

[0023] A2. Place the modified catalyst precursor and 1,2-dichloroethane in a reaction vessel, stir at room temperature for 5-10 min, add sulfuric acid solution, heat the reaction vessel to 75-85℃, keep the temperature for 4-6 h, and then perform post-treatment to obtain the modified catalyst.

[0024] The reaction principle for preparing the modified catalyst is as follows:

[0025] During the reaction, polyvinyl alcohol acts as a protective colloid to disperse styrene and divinylbenzene into oil-phase droplets. At 65-75℃, benzoyl peroxide thermally decomposes to generate free radicals, which then undergo free radical suspension polymerization within the droplets. Divinylbenzene provides crosslinking sites, forming a mechanically stable and swellable modified catalyst precursor. Further, the modified catalyst precursor microspheres are fully swollen with 1,2-dichloroethane. Subsequently, sulfuric acid is added at 75-85℃ for electrophilic aromatic substitution sulfonation, with -SO3H anchored on the benzene ring. The crosslinking network prevents swelling and disintegration and limits the degree of sulfonation, resulting in a supported strong acid resin catalyst with controllable pore structure and acid site distribution. The swelling medium 1,2-dichloroethane reduces mass transfer resistance and avoids unsulfonated cores caused by surface shell formation, ultimately yielding the modified catalyst.

[0026] Further, in step A1, the ratio of polyvinyl alcohol, deionized water, styrene, divinylbenzene, and benzoyl peroxide is 0.5-1g:150-200mL:15-20g:3-5g:0.1-0.2g. The post-processing steps include: after the reaction is completed, the reaction vessel is heated to 85-95℃ and aged for 2 hours. After the reaction system is cooled to room temperature, it is filtered. The filter cake is washed 2-4 times with deionized water and ethanol, transferred to an oven at 50-60℃, and dried to constant weight to obtain the modified catalyst precursor.

[0027] Further, in step A2, the ratio of the modified catalyst precursor, 1,2-dichloroethane, and sulfuric acid solution is 2-4 g: 4-6 mL: 20-40 mL, and the concentration of the sulfuric acid solution is 95-98 wt%. The post-treatment steps include: after the reaction is completed, the reaction system is cooled to a higher temperature, filtered, the filter cake is washed 2-4 times with deionized water and ethanol, transferred to an oven at 50-60°C, and dried to constant weight to obtain the modified catalyst.

[0028] Furthermore, the modified toughening agent is prepared by the following steps:

[0029] B1. Methyl methacrylate, styrene, glycidyl methacrylate, fatty acid soap and deionized water are placed in a reaction vessel and mixed evenly to obtain the shell monomer.

[0030] B2. Place the seed latex in a reaction vessel and stir. Heat the reaction vessel to 55-65℃, add shell monomer and cumene hydroperoxide dropwise, heat to 65-75℃, and keep the reaction at this temperature for 2-4 hours. The modified toughening agent is then obtained through post-treatment.

[0031] The preparation reaction principle of the modified toughening agent is as follows:

[0032] In the reaction process, methyl methacrylate, styrene, glycidyl methacrylate, and fatty acid soap are pre-dispersed into a shell monomer emulsion. Further, at 55-65℃, the shell monomer and cumene hydroperoxide are added dropwise to the system containing seed particles. The cumene hydroperoxide generates free radicals on the particle surface and initiates the reaction in situ at the seed particle interface at a temperature of 65-75℃. Methyl methacrylate, styrene, and glycidyl methacrylate are grafted and epitaxially grown at the core-shell interface to form a dense shell. The epoxy groups on the glycidyl methacrylate are retained during the polymerization process, providing active sites for subsequent chemical crosslinking with the matrix or core phase, ultimately yielding a modified toughening agent.

[0033] Further, in step B1, the ratio of methyl methacrylate, styrene, glycidyl methacrylate, fatty acid soap, and deionized water is 10-12g:2-4g:1.5-2.5g:0.1-0.2g:15-20mL; in step B2, the ratio of seed latex, shell monomer, and cumene hydroperoxide is 15-20g:5-10mL:0.2-0.4g. The post-treatment step includes: after the reaction is completed, wait for the reaction system to cool to room temperature, add 5wt% ammonium bicarbonate aqueous solution to the reaction solution to adjust the pH of the system to 8, transfer the reaction solution to a rotary evaporator at a temperature of 60-70℃, and evaporate under reduced pressure until no liquid is collected to obtain the modified toughening agent.

[0034] Furthermore, the seed latex is prepared by the following steps:

[0035] C1. Place the mixed monomers, fatty acid soaps and cumene hydroperoxide in a reaction vessel and mix them evenly to obtain a pre-emulsion;

[0036] C2. Place deionized water, sodium pyrophosphate and fatty acid soap in a reaction vessel and stir. Heat the reaction vessel to 55-65℃, add glucose and ferrous sulfite solution, keep warm and stir for 5-10 minutes, add pre-emulsion dropwise, and then process to obtain seed latex.

[0037] The reaction principle for preparing seed latex is as follows:

[0038] During the reaction, fatty acid soaps uniformly disperse the mixed monomers and cumene hydroperoxide into a pre-emulsion, allowing cumene hydroperoxide to preferentially distribute within the oil phase micelles. Further, at 55-65°C, a glucose and ferrous sulfate system is added to the aqueous phase. Glucose continuously maintains the activity of ferrous ions. After a short period of heat preservation, the pre-emulsion is added dropwise. Ferrous ions react with cumene hydroperoxide via a red oxygen reaction to generate free radicals, which initiate the polymerization of the mixed monomers at the micelle interface, forming primitive nucleated particles. Sodium pyrophosphate complexes the metal ions and buffers the activity of ferrous ions, inhibiting ineffective decomposition. The fatty acid soaps further reduce interfacial tension, providing electrostatic and steric stability to prevent particle aggregation. The mixed monomers grow heterogeneously on the existing seed surface, ultimately yielding a seed latex with narrow particle size and good stability.

[0039] Further, in step C1, the weight ratio of the mixed monomers, fatty acid soap, and cumene hydroperoxide is 8-10:0.15-0.2:0.01-0.02, and the mixed monomers are composed of butyl acrylate, methyl methacrylate, 1,4-butanediol diacrylate, and allyl methacrylate in a mass ratio of 8:1:0.1:0.05; in step C2, the ratio of deionized water, sodium pyrophosphate, fatty acid soap, glucose, ferrous sulfite solution, and preemulsion is 50-7. 0 mL: 0.5-1 g: 0.1-0.2 g: 0.1-0.2 g: 0.5-1 mL: 120-140 mL, the concentration of ferrous sulfite solution is 0.5-1 wt%, the post-treatment steps include: after the reaction is completed, wait for the reaction system to cool to room temperature, add 5 wt% ammonium bicarbonate aqueous solution to the reaction solution to adjust the pH of the system to 8, transfer the reaction solution to a rotary evaporator at a temperature of 60-70℃, and remove unreacted monomers by rotary evaporation under reduced pressure to obtain seed latex.

[0040] The present invention has the following beneficial effects:

[0041] 1. The modified toughening agent prepared in this invention uses butyl acrylate, methyl methacrylate, 1,4-butanediol diacrylate, and allyl methacrylate as main monomers. It forms elastic polymer particles with a core-shell structure through a seed emulsion polymerization method. The core layer of this modified toughening agent is a flexible acrylate rubber phase, and the shell layer is a rigid glassy phase containing a copolymer of glycidyl methacrylate and styrene-methyl methacrylate. The active epoxy groups in the shell layer can react with the terminal carboxyl or hydroxyl groups of the polyester molecules, achieving chemical grafting and interfacial crosslinking during melt blending, thereby forming a chemically bonded microphase within the polyester matrix. The dispersed structure improves the compatibility and dispersibility of the modified toughening agent in the polyester matrix, significantly improves interfacial stress transmission, and further enhances the toughness and strength of the fiber fabric. At the same time, the flexible rubber core of the modified toughening agent can absorb impact energy and generate reversible deformation under external force, preventing rapid crack propagation and delaying the breakage of polyester molecular chains. This significantly improves the toughness and elongation at break of the modified polyester fiber. Furthermore, the modified toughening agent also improves the excellent elastic recovery performance and soft touch of the polyester fiber, allowing the fiber fabric to quickly recover its original shape after repeated stretching or bending, thus improving the elasticity of recycled polyester fabric.

[0042] 2. The modified catalyst prepared in this invention uses styrene and divinylbenzene as backbone monomers. A cross-linked porous resin support is formed through suspension polymerization in a polyvinyl alcohol stable system, followed by sulfonation with concentrated sulfuric acid to obtain a solid acidic catalyst containing a large number of -SO3H functional groups. This catalyst possesses high specific surface area, good mechanical strength, and abundant acidic active sites. Its internal porous structure enhances the diffusion and mass transfer efficiency of reactants, and the -SO3H groups provide strong acidic sites to promote ester bond cleavage, accelerating the decomposition of polyester chains into monomers, thereby significantly improving the hydrolysis rate and monomer yield. The regenerated p-phenylene obtained through this catalyst... Diformic acid is characterized by high purity, low impurities, and low color, providing a high-quality raw material for subsequent copolymerization reactions. The pure monomer can reduce the influence of metal ions or degradation products during polycondensation, resulting in a more uniform molecular weight distribution and complete chain structure in the modified polyester. High-quality modified polyester, as a spinning raw material, can significantly improve the rheological properties of the melt and the formability of the fiber, making the fiber breaking strength, elongation, and orientation all superior to the unmodified system. The resulting modified polyester fiber has high crystallinity and good thermal stability, and is not easily degraded or discolored during spinning. The fiber surface is smooth and the structure is dense, improving the excellent strength and abrasion resistance of the finished fiber fabric.

[0043] 3. This invention also involves copolymerizing 2,2-dimethyl-1,3-propanediol and 2,6-naphthalenedicarboxylic acid during the preparation of recycled polyester to obtain modified polyester. The segments of 2,2-dimethyl-1,3-propanediol increase the freedom and flexibility of the polyester molecular chain, improving the elongation at break and elastic recovery performance of the polyester fiber. The rigid aromatic ring structure of 2,6-naphthalenedicarboxylic acid enhances the orientation and crystallinity of the molecular chain, improving the tensile strength and thermal stability of the fiber, making the fiber structure more stable during stretching and heat treatment. Furthermore, the core-shell structured acrylate-based toughening agent forms a fine and uniformly dispersed elastic phase in the polyester matrix. The rubber core can absorb and alleviate local stress concentration under frictional stress, and the shell layer and polyester chain... The chemical bonding of segments enhances interfacial bonding, thereby preventing the early propagation of microcracks and improving the structural integrity of the fiber fabric under repeated friction. Secondly, the introduction of modified catalysts enables waste polyester to be efficiently depolymerized into high-purity terephthalic acid, significantly reducing impurity content and molecular chain breakage defects, increasing the molecular weight and regularity of recycled polyester, enhancing fiber orientation and crystallinity, and providing a stable structural basis for wear resistance. The rigid naphthalene ring structure in the copolymerized modified polyester enhances interchain forces and surface density, while the flexible segments improve the fiber's deformation recovery ability during abrasion, making the fiber less prone to breakage or pilling due to friction. The synergistic effect of these three factors enables the resulting fiber fabric to maintain low mass loss and surface damage during long-term friction cycles. Detailed Implementation

[0044] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] The waste polyester fibers used in this invention were purchased from Jiangsu Shenghong Technology Co., Ltd.

[0046] The p-toluenesulfonic acid used in this invention was purchased from Langfang Qianyao Technology Co., Ltd. It is in the form of flaky crystals, grade one, and branded by Qianyao Technology.

[0047] Example 1

[0048] This embodiment provides a method for preparing a modified toughening agent for producing high-elasticity polyester fiber fabrics from recycled polyester, comprising the following steps:

[0049] Step ①: Preparation of pre-emulsion

[0050] Butyl acrylate, methyl methacrylate, 1,4-butanediol diacrylate and allyl methacrylate are mixed evenly in a mass ratio of 8:1:0.1:0.05 and set aside.

[0051] Weigh out 80g of mixed monomers, 1.5g of fatty acid soap and 0.1g of cumene hydroperoxide and place them in a reaction vessel. Mix them evenly to obtain a pre-emulsion.

[0052] Step 2: Prepare seed latex

[0053] Weigh out 500 mL of deionized water, 5 g of sodium pyrophosphate, and 1 g of fatty acid soap and place them in a reaction vessel. Stir the reaction vessel and heat it to 55°C. Add 1 g of glucose and 5 mL of 0.5 wt% ferrous sulfite solution. Keep the mixture warm and stir for 5 min. Add 1200 mL of pre-emulsion dropwise. After the reaction is complete, wait for the reaction system to cool to room temperature. Add 5 wt% ammonium bicarbonate aqueous solution to the reaction solution to adjust the pH of the system to 8. Transfer the reaction solution to a rotary evaporator at 60°C and remove unreacted monomers by rotary evaporation under reduced pressure to obtain seed latex.

[0054] Step ③: Preparation of shell monomers

[0055] Weigh out 100g of methyl methacrylate, 20g of styrene, 15g of glycidyl methacrylate, 1g of fatty acid soap, and 150mL of deionized water and place them in a reaction vessel. Mix them evenly to obtain the shell monomer.

[0056] Step 4: Preparation of modified toughening agent

[0057] Weigh 150g of seed latex and place it in a reaction vessel and stir. Heat the reaction vessel to 55℃, add 50mL of shell monomer and 2g of cumene hydroperoxide, heat to 65℃, and keep the reaction at this temperature for 2 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, add 5wt% ammonium bicarbonate aqueous solution to the reaction solution to adjust the pH of the system to 8, transfer the reaction solution to a rotary evaporator at 60℃, and evaporate under reduced pressure until no liquid is collected to obtain the modified toughening agent.

[0058] Example 2

[0059] This embodiment provides a method for preparing a modified toughening agent for producing high-elasticity polyester fiber fabrics from recycled polyester, comprising the following steps:

[0060] Step ①: Preparation of pre-emulsion

[0061] Butyl acrylate, methyl methacrylate, 1,4-butanediol diacrylate and allyl methacrylate are mixed evenly in a mass ratio of 8:1:0.1:0.05 and set aside.

[0062] Weigh out 90g of mixed monomers, 1.7g of fatty acid soap and 0.15g of cumene hydroperoxide and place them in a reaction vessel. Mix them evenly to obtain a pre-emulsion.

[0063] Step 2: Prepare seed latex

[0064] Weigh out 600 mL of deionized water, 7 g of sodium pyrophosphate, and 1.5 g of fatty acid soap and place them in a reaction vessel. Stir the reaction vessel and heat it to 60°C. Add 1.5 g of glucose and 7 mL of 0.7 wt% ferrous sulfite solution. Keep the mixture warm and stir for 7 min. Add 1300 mL of pre-emulsion dropwise. After the reaction is complete, wait for the reaction system to cool to room temperature. Add 5 wt% ammonium bicarbonate aqueous solution to the reaction solution to adjust the pH of the system to 8. Transfer the reaction solution to a rotary evaporator at 65°C and remove unreacted monomers by rotary evaporation under reduced pressure to obtain seed latex.

[0065] Step ③: Preparation of shell monomers

[0066] Weigh out 110g of methyl methacrylate, 30g of styrene, 20g of glycidyl methacrylate, 1.5g of fatty acid soap, and 175mL of deionized water and place them in a reaction vessel. Mix them thoroughly to obtain the shell monomer.

[0067] Step 4: Preparation of modified toughening agent

[0068] Weigh 175g of seed latex and place it in a reaction vessel and stir. Heat the reaction vessel to 60℃, add 70mL of shell monomer and 3g of cumene hydroperoxide, heat to 70℃, and keep the temperature for 3h. After the reaction is complete, wait for the reaction system to cool to room temperature, add 5wt% ammonium bicarbonate aqueous solution to the reaction solution to adjust the pH of the system to 8, transfer the reaction solution to a rotary evaporator at 65℃, and evaporate under reduced pressure until no liquid is collected to obtain the modified toughening agent.

[0069] Example 3

[0070] This embodiment provides a method for preparing a modified toughening agent for producing high-elasticity polyester fiber fabrics from recycled polyester, comprising the following steps:

[0071] Step ①: Preparation of pre-emulsion

[0072] Butyl acrylate, methyl methacrylate, 1,4-butanediol diacrylate and allyl methacrylate are mixed evenly in a mass ratio of 8:1:0.1:0.05 and set aside.

[0073] Weigh out 100g of mixed monomers, 2g of fatty acid soap and 0.2g of cumene hydroperoxide and place them in a reaction vessel. Mix them evenly to obtain a pre-emulsion.

[0074] Step 2: Prepare seed latex

[0075] Weigh out 700 mL of deionized water, 10 g of sodium pyrophosphate, and 2 g of fatty acid soap and place them in a reaction vessel. Stir the reaction vessel and heat it to 65°C. Add 2 g of glucose and 10 mL of 1 wt% ferrous sulfite solution. Keep the mixture warm and stir for 10 min. Add 1400 mL of pre-emulsion dropwise. After the reaction is complete, wait for the reaction system to cool to room temperature. Add 5 wt% ammonium bicarbonate aqueous solution to the reaction solution to adjust the pH of the system to 8. Transfer the reaction solution to a rotary evaporator at 70°C and remove unreacted monomers by rotary evaporation under reduced pressure to obtain seed latex.

[0076] Step ③: Preparation of shell monomers

[0077] Weigh out 120g of methyl methacrylate, 40g of styrene, 25g of glycidyl methacrylate, 2g of fatty acid soap, and 200mL of deionized water and place them in a reaction vessel. Mix them evenly to obtain the shell monomer.

[0078] Step 4: Preparation of modified toughening agent

[0079] Weigh 200g of seed latex and place it in a reaction vessel and stir. Heat the reaction vessel to 65℃, add 100mL of shell monomer and 4g of cumene hydroperoxide, heat to 75℃, and keep the temperature for 4 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, add 5wt% ammonium bicarbonate aqueous solution to the reaction solution to adjust the pH of the system to 8, transfer the reaction solution to a rotary evaporator at 70℃, and evaporate under reduced pressure until no liquid is collected to obtain the modified toughening agent.

[0080] Example 4

[0081] This embodiment provides a method for preparing a modified catalyst for producing high-elasticity polyester fiber fabric from recycled polyester, comprising the following steps:

[0082] Step I: Preparation of modified catalyst precursor

[0083] Weigh out 5g of polyvinyl alcohol and 1500mL of deionized water and place them in a reaction vessel. Heat the reaction vessel to 50℃ and stir for 15min. Add 150g of styrene, 30g of divinylbenzene and 1g of benzoyl peroxide. Heat the reaction vessel to 65℃ and keep it at that temperature for 4h. After the reaction is complete, heat the reaction vessel to 85℃ and mature for 2h. After the reaction system cools to room temperature, filter it. Wash the filter cake twice with deionized water and ethanol, transfer it to an oven at 50℃, and dry it to constant weight to obtain the modified catalyst precursor.

[0084] Step II: Preparation of modified catalyst

[0085] Weigh 20g of the modified catalyst precursor and 40mL of 1,2-dichloroethane and place them in a reaction vessel. Stir at room temperature for 5min, add 200mL of 95wt% sulfuric acid solution, heat the reaction vessel to 75℃, and keep the temperature for 4h. After the reaction is complete, wait for the reaction system to cool down, filter, wash the filter cake twice with deionized water and ethanol, transfer it to an oven at 50℃, and dry it to constant weight to obtain the modified catalyst.

[0086] Example 5

[0087] This embodiment provides a method for preparing a modified catalyst for producing high-elasticity polyester fiber fabric from recycled polyester, comprising the following steps:

[0088] Step I: Preparation of modified catalyst precursor

[0089] Weigh 7.5g of polyvinyl alcohol and 1750mL of deionized water into a reaction vessel. Heat the reaction vessel to 55℃ and stir for 20min. Add 175g of styrene, 40g of divinylbenzene and 1.5g of benzoyl peroxide. Heat the reaction vessel to 70℃ and react for 5h. After the reaction is complete, heat the reaction vessel to 90℃ and mature for 2h. After the reaction system cools to room temperature, filter the mixture. Wash the filter cake three times with deionized water and ethanol. Transfer the cake to an oven at 55℃ and dry it to constant weight to obtain the modified catalyst precursor.

[0090] Step II: Preparation of modified catalyst

[0091] Weigh 30g of the modified catalyst precursor and 50mL of 1,2-dichloroethane and place them in a reaction vessel. Stir at room temperature for 7min, add 300mL of 96wt% sulfuric acid solution, heat the reaction vessel to 80℃, and keep the temperature for 5h. After the reaction is complete, wait for the reaction system to cool down, filter, wash the filter cake three times with deionized water and ethanol, transfer it to an oven at 55℃, and dry it to constant weight to obtain the modified catalyst.

[0092] Example 6

[0093] This embodiment provides a method for preparing a modified catalyst for producing high-elasticity polyester fiber fabric from recycled polyester, comprising the following steps:

[0094] Step I: Preparation of modified catalyst precursor

[0095] Weigh 10g of polyvinyl alcohol and 2000mL of deionized water and place them in a reaction vessel. Heat the reaction vessel to 60℃ and stir for 30min. Add 200g of styrene, 50g of divinylbenzene and 2g of benzoyl peroxide. Heat the reaction vessel to 75℃ and keep it at that temperature for 6h. After the reaction is complete, heat the reaction vessel to 95℃ and mature for 2h. After the reaction system cools to room temperature, filter it. Wash the filter cake four times with deionized water and ethanol. Transfer it to an oven at 60℃ and dry it to constant weight to obtain the modified catalyst precursor.

[0096] Step II: Preparation of modified catalyst

[0097] Weigh 40g of the modified catalyst precursor and 60mL of 1,2-dichloroethane and place them in a reaction vessel. Stir at room temperature for 10min, add 400mL of 98wt% sulfuric acid solution, heat the reaction vessel to 85℃, and keep the temperature for 6h. After the reaction is complete, wait for the reaction system to cool down, filter, wash the filter cake 4 times with deionized water and ethanol, transfer it to an oven at 60℃, and dry it to constant weight to obtain the modified catalyst.

[0098] Example 7

[0099] This embodiment provides a method for preparing high-elasticity polyester fiber fabric by polyester recycling, including the following steps:

[0100] Step 1: Preparation of Regenerated Terephthalic Acid

[0101] Weigh out 80g of waste polyester fiber, 800mL of deionized water, and 0.5g of the modified catalyst prepared in Example 4 and place them in a high-pressure reactor at 195℃. Keep the reactor at this temperature for 2 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, add 100mL of 0.5mol / L sodium hydroxide aqueous solution to the reaction solution, stir for 0.5 hours, filter, add 0.5mol / L hydrochloric acid aqueous solution to the filtrate until no more precipitate is formed, filter again, transfer the filter cake to an oven at 50℃, and dry to constant weight to obtain regenerated terephthalic acid.

[0102] Step 2: Preparation of modified polyester

[0103] Weigh out 70g of recycled terephthalic acid, 20g of 2,2-dimethyl-1,3-propanediol, 40g of 2,6-naphthalenedicarboxylic acid, 60g of ethylene glycol, 0.04g of antimony glycolate, 0.024g of triphenyl phosphite, and 0.1g of tetrabutyl titanate and place them in a high-pressure reactor under nitrogen atmosphere. Evacuate the reaction system to a vacuum pressure of -0.1MPa. Heat the high-pressure reactor to 230℃ and maintain the temperature for 2 hours. Then heat the high-pressure reactor to 265℃ and maintain the temperature for 0.5 hours to obtain modified polyester.

[0104] Step 3: Preparation of modified polyester fibers

[0105] Dioctyl phthalate, polyvinyl alcohol and stearic acid were mixed evenly in a mass ratio of 4:1:3 to obtain an auxiliary additive, which was then set aside.

[0106] 600g of modified polyester, 100g of the modified toughening agent prepared in Example 1 and 10g of auxiliary additives were added to a twin-screw extruder. After melting, the melt was filtered and homogenized at the spinning assembly and then extruded through the spinneret. After entering the side blowing chamber and being cooled and solidified by the side blowing air, modified polyester fiber was obtained.

[0107] The twin-screw extruder has eight temperature zones from the feed inlet to the discharge outlet, with temperatures of 240℃, 240℃, 250℃, 250℃, 265℃, 265℃, 280℃, and 280℃ respectively. The main motor speed of the twin-screw extruder is 120 rpm, and the pressure is 80 bar.

[0108] Step 4: Preparation of polyester fiber fabric

[0109] After drying, the modified polyester fibers are oiled, stretched, and wound into yarn bobbins at high speed. Finally, they are graded, inspected, and packaged to obtain modified polyester yarn. After warping and sizing, the modified polyester yarn is woven into greige fabric. The greige fabric is then boiled, dyed, set, and finished to obtain modified polyester fiber fabric.

[0110] Example 8

[0111] This embodiment provides a method for preparing high-elasticity polyester fiber fabric by polyester recycling, including the following steps:

[0112] Step 1: Preparation of Regenerated Terephthalic Acid

[0113] Weigh 90g of waste polyester fiber, 900mL of deionized water, and 0.75g of the modified catalyst prepared in Example 5 and place them in a high-pressure reactor at 200℃. Keep the reactor at this temperature for 2.5h. After the reaction is complete, wait for the reaction system to cool to room temperature, add 125mL of 0.75mol / L sodium hydroxide aqueous solution to the reaction solution, stir for 1h, filter, add 0.7mol / L hydrochloric acid aqueous solution to the filtrate until no more precipitate is formed, filter again, transfer the filter cake to an oven at 55℃, and dry to constant weight to obtain regenerated terephthalic acid.

[0114] Step 2: Preparation of modified polyester

[0115] Weigh out 80g of recycled terephthalic acid, 30g of 2,2-dimethyl-1,3-propanediol, 50g of 2,6-naphthalenedicarboxylic acid, 70g of ethylene glycol, 0.05g of antimony glycolate, 0.03g of triphenyl phosphite, and 0.15g of tetrabutyl titanate and place them in a high-pressure reactor under nitrogen atmosphere. Evacuate the reaction system to a vacuum pressure of -0.1MPa. Heat the high-pressure reactor to 240℃ and maintain the temperature for 3 hours. Then heat the high-pressure reactor to 275℃ and maintain the temperature for 1 hour to obtain modified polyester.

[0116] Step 3: Preparation of modified polyester fibers

[0117] Dioctyl phthalate, polyvinyl alcohol and stearic acid were mixed evenly in a mass ratio of 4:1:3 to obtain an auxiliary additive, which was then set aside.

[0118] 700g of modified polyester, 110g of the modified toughening agent prepared in Example 2 and 20g of auxiliary additives were added to a twin-screw extruder. After melting, the melt was filtered and homogenized at the spinning assembly and then extruded through the spinneret. After entering the side blowing chamber and being cooled and solidified by the side blowing, modified polyester fiber was obtained.

[0119] The twin-screw extruder has eight temperature zones from the feed inlet to the discharge outlet, with temperatures of 240℃, 240℃, 250℃, 250℃, 265℃, 265℃, 280℃, and 280℃ respectively. The main motor speed of the twin-screw extruder is 140 rpm, and the pressure is 100 bar.

[0120] Step 4: Preparation of polyester fiber fabric

[0121] After drying, the modified polyester fibers are oiled, stretched, and wound into yarn bobbins at high speed. Finally, they are graded, inspected, and packaged to obtain modified polyester yarn. After warping and sizing, the modified polyester yarn is woven into greige fabric. The greige fabric is then boiled, dyed, set, and finished to obtain modified polyester fiber fabric.

[0122] Example 9

[0123] This embodiment provides a method for preparing high-elasticity polyester fiber fabric by polyester recycling, including the following steps:

[0124] Step 1: Preparation of Regenerated Terephthalic Acid

[0125] Weigh 100g of waste polyester fiber, 1000mL of deionized water, and 1g of the modified catalyst prepared in Example 6 and place them in a high-pressure reactor at 205℃. Keep the reactor at this temperature for 3 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, add 150mL of 1mol / L sodium hydroxide aqueous solution to the reaction solution, stir for 1 hour, filter, add 1mol / L hydrochloric acid aqueous solution to the filtrate until no more precipitate is formed, filter again, transfer the filter cake to an oven at 60℃, and dry to constant weight to obtain regenerated terephthalic acid.

[0126] Step 2: Preparation of modified polyester

[0127] Weigh out 100g of recycled terephthalic acid, 40g of 2,2-dimethyl-1,3-propanediol, 60g of 2,6-naphthalenedicarboxylic acid, 80g of ethylene glycol, 0.06g of antimony glycolate, 0.04g of triphenyl phosphite, and 0.3g of tetrabutyl titanate and place them in a high-pressure reactor under nitrogen atmosphere. Evacuate the reaction system to a vacuum pressure of -0.1MPa. Heat the high-pressure reactor to 250℃ and maintain the temperature for 4 hours. Then heat the high-pressure reactor to 285℃ and maintain the temperature for 1 hour to obtain modified polyester.

[0128] Step 3: Preparation of modified polyester fibers

[0129] Dioctyl phthalate, polyvinyl alcohol and stearic acid were mixed evenly in a mass ratio of 4:1:3 to obtain an auxiliary additive, which was then set aside.

[0130] 800g of modified polyester, 120g of the modified toughening agent prepared in Example 3 and 30g of auxiliary additives were added to a twin-screw extruder. After melting, the melt was filtered and homogenized at the spinning assembly and then extruded through the spinneret. After entering the side blowing chamber and being cooled and solidified by the side blowing, modified polyester fiber was obtained.

[0131] The twin-screw extruder has eight temperature zones from the feed inlet to the discharge outlet, with temperatures of 240℃, 240℃, 250℃, 250℃, 265℃, 265℃, 280℃, and 280℃ respectively. The main motor speed of the twin-screw extruder is 160 rpm, and the pressure is 120 bar.

[0132] Step 4: Preparation of polyester fiber fabric

[0133] After drying, the modified polyester fibers are oiled, stretched, and wound into yarn bobbins at high speed. Finally, they are graded, inspected, and packaged to obtain modified polyester yarn. After warping and sizing, the modified polyester yarn is woven into greige fabric. The greige fabric is then boiled, dyed, set, and finished to obtain modified polyester fiber fabric.

[0134] Comparative Example 1

[0135] The difference between this comparative example and Example 9 is that the toughening agent was omitted in step three when preparing the modified polyester fiber.

[0136] Comparative Example 2

[0137] The difference between this comparative example and Example 9 is that, in step one, when preparing regenerated terephthalic acid, commercially available p-toluenesulfonic acid is used in an equal amount to replace the modified catalyst.

[0138] Comparative Example 3

[0139] The difference between this comparative example and Example 9 is that, in step two, when preparing the modified polyester, the use of 2,2-dimethyl-1,3-propanediol and 2,6-naphthalenedicarboxylic acid was omitted.

[0140] Performance testing:

[0141] The tensile strength and elongation at break of the polyester fiber fabrics prepared in Examples 7-9 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 3923.1-2013 "Textiles - Tensile Properties of Fabrics - Part 1: Determination of Breaking Strength and Elongation at Break (Strip Method)".

[0142] The elastic recovery rate of the polyester fiber fabrics prepared in Examples 7-9 and Comparative Examples 1-3 under a constant force of 25 N was tested in accordance with the standard FZ / T 01034-2008 "Textiles - Test Method for Tensile Elasticity of Woven Fabrics".

[0143] The abrasion resistance index of the polyester fiber fabrics prepared in Examples 7-9 and Comparative Examples 1-3 was tested according to the standard GB / T 21196.3-2007 "Textiles - Martindale Method - Determination of Abrasion Resistance of Fabrics - Part 3: Determination of Mass Loss". The specific data are shown in Table 1.

[0144] Table 1 - Performance test data of each sample

[0145]

[0146] Data Analysis:

[0147] Comparative analysis of the data in Table 1 shows that the polyester fiber fabric prepared by this invention has a breaking strength of 452.3 N, a breaking elongation of 56.9%, an elastic recovery rate of 92.6%, and an abrasion resistance index of 2995 cycles / mg. -1This invention demonstrates that waste polyester fibers are recycled through catalytic recovery, copolymerization modification, and toughening enhancement. By preparing a modified catalyst with a porous structure and sulfonic acid functional groups, polyester is efficiently depolymerized into high-purity terephthalic acid under mild conditions. The recycled terephthalic acid is then copolymerized with 2,6-naphthalenedicarboxylic acid and 2,2-dimethyl-1,3-propanediol, giving the polyester molecular chain higher rigidity and thermal stability. At the same time, a core-shell structured acrylate-based toughening agent is introduced to effectively improve the toughness and elasticity of the polyester. Furthermore, through melt spinning and weaving processes, polyester fiber fabric is produced, which not only improves the toughness and strength of the fiber fabric but also enhances its abrasion resistance.

[0148] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing high-elasticity polyester fiber fabric by polyester recycling, characterized in that, Includes the following steps: S1. Place waste polyester fiber, deionized water and modified catalyst in a high-pressure reactor at a temperature of 195-205℃ and keep it at the temperature for 2-3 hours. Then, after processing, regenerated terephthalic acid is obtained. S2. Recycled terephthalic acid, 2,2-dimethyl-1,3-propanediol, 2,6-naphthalenedicarboxylic acid, ethylene glycol, antimony glycolate, triphenyl phosphite, and tetrabutyl titanate are placed in a high-pressure reactor under nitrogen atmosphere. The reaction system is evacuated to a vacuum pressure of -0.1 MPa. The high-pressure reactor is heated to 230-250℃ and kept at this temperature for 2-4 hours. Then, the high-pressure reactor is heated to 265-285℃ and kept at this temperature for 0.5-1 hour to obtain modified polyester. S3. Modified polyester, modified toughening agent and auxiliary additives are added to a twin-screw extruder and melt-spun to obtain modified polyester fiber; S4. The modified polyester fiber is spun to obtain polyester fiber fabric. The modified catalyst was prepared by the following steps: A1. Place polyvinyl alcohol and deionized water in a reaction vessel, heat the reaction vessel to 50-60℃, stir for 15-30 min, add styrene, divinylbenzene and benzoyl peroxide, heat the reaction vessel to 65-75℃, keep the reaction for 4-6 h, and then process to obtain the modified catalyst precursor. A2. Place the modified catalyst precursor and 1,2-dichloroethane in a reaction vessel, stir at room temperature for 5-10 min, add sulfuric acid solution, heat the reaction vessel to 75-85℃, keep the temperature for 4-6 h, and then process to obtain the modified catalyst. The modified toughening agent is prepared by the following steps: B1. Methyl methacrylate, styrene, glycidyl methacrylate, fatty acid soap and deionized water are placed in a reaction vessel and mixed evenly to obtain the shell monomer. B2. Place the seed latex in a reaction vessel and stir. Heat the reaction vessel to 55-65℃, add shell monomer and cumene hydroperoxide dropwise, heat to 65-75℃, and keep the reaction at this temperature for 2-4 hours. The modified toughening agent is then obtained through post-treatment.

2. The method for preparing high-elasticity polyester fiber fabric by polyester recycling according to claim 1, characterized in that, In step S1, the ratio of waste polyester fiber, deionized water, and modified catalyst is 8-10g:80-100mL:0.05-0.1g; in step S2, the weight ratio of regenerated terephthalic acid, 2,2-dimethyl-1,3-propanediol, 2,6-naphthalenedicarboxylic acid, ethylene glycol, antimony glycolate, triphenyl phosphite, and tetrabutyl titanate is 7-10:2-4:4-6:6-8:0.004-0.006:0.002-0.004:0.01-0.03; in step S3, the weight ratio of modified polyester, modified toughening agent, and auxiliary additives is 60-80:10-12:1-3.

3. The method for preparing high-elasticity polyester fiber fabric by polyester recycling according to claim 1, characterized in that, In step A1, the ratio of polyvinyl alcohol, deionized water, styrene, divinylbenzene, and benzoyl peroxide is 0.5-1g:150-200mL:15-20g:3-5g:0.1-0.2g; in step A2, the ratio of the modified catalyst precursor, 1,2-dichloroethane, and sulfuric acid solution is 2-4g:4-6mL:20-40mL, and the concentration of the sulfuric acid solution is 95-98wt%.

4. The method for preparing high-elasticity polyester fiber fabric by polyester recycling according to claim 1, characterized in that, In step B1, the ratio of methyl methacrylate, styrene, glycidyl methacrylate, fatty acid soap, and deionized water is 10-12g:2-4g:1.5-2.5g:0.1-0.2g:15-20mL; in step B2, the ratio of seed latex, shell monomer, and cumene hydroperoxide is 15-20g:5-10mL:0.2-0.4g.

5. The method for preparing high-elasticity polyester fiber fabric by polyester recycling according to claim 1, characterized in that, The seed latex is prepared by the following steps: C1. Place the mixed monomers, fatty acid soaps and cumene hydroperoxide in a reaction vessel and mix them evenly to obtain a pre-emulsion; C2. Place deionized water, sodium pyrophosphate and fatty acid soap in a reaction vessel and stir. Heat the reaction vessel to 55-65℃, add glucose and ferrous sulfite solution, keep warm and stir for 5-10 minutes, add pre-emulsion dropwise, and then process to obtain seed latex.

6. The method for preparing high-elasticity polyester fiber fabric by polyester recycling according to claim 5, characterized in that, In step C1, the weight ratio of the mixed monomers, fatty acid soap, and cumene hydroperoxide is 8-10:0.15-0.2:0.01-0.02, and the mixed monomers are composed of butyl acrylate, methyl methacrylate, 1,4-butanediol diacrylate, and allyl methacrylate in a mass ratio of 8:1:0.1:0.05; in step C2, the volume ratio of deionized water, sodium pyrophosphate, glucose, ferrous sulfite solution, and preemulsion is 50-70 mL:0.5-1 g:0.1-0.2 g:0.5-1 mL:120-140 mL, and the concentration of the ferrous sulfite solution is 0.5-1 wt%.

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