Flame-retardant modified wear-resistant polyester fiber and preparation method thereof

Abstract

This invention discloses a flame-retardant modified abrasion-resistant polyester fiber and its preparation method, belonging to the field of polyester fiber technology. It addresses the technical problem that the flame retardancy and abrasion resistance of polyester fibers in existing technologies need further improvement. Specifically, the method includes the following steps: reacting DDP, nitrogen-modified carbon dot dispersant, terephthalic acid, ethylene glycol, and additives to obtain modified polyethylene terephthalate; melt-extruding and spinning the modified polyethylene terephthalate, ethylene glycol, and modified filler to obtain abrasion-resistant polyester fiber. This invention modifies polyethylene terephthalate and adds modified filler. Through the molecular-level chemical flame retardancy of the modified polyethylene terephthalate and the physical barrier effect of the filler, a combustion-inhibiting and propagation-preventing effect is achieved. Furthermore, the combined effect of the lamellar and granular structures of the filler improves the abrasion resistance of the material.

Description

Technical Field

[0001] This invention relates to the field of polyester fiber technology, specifically to a flame-retardant modified abrasion-resistant polyester fiber and its preparation method. Background Technology

[0002] Polyethylene terephthalate (PET) polyester fiber has become a core raw material in the textile industry, filter materials, and packaging materials due to its excellent properties such as high strength, good wrinkle resistance, and chemical corrosion resistance, and occupies an important position in the national economy. However, polyester fiber has a low limiting oxygen index of only 20% to 22%, making it a flammable fiber. At the same time, it easily produces a large amount of flammable substances when heated and decomposed, which can easily cause fires. Furthermore, the molten droplets produced after combustion can easily cause secondary combustion, which limits its widespread application.

[0003] Traditional polyester fiber manufacturing processes mainly use inorganic flame retardants as additives. Inorganic flame retardants are inorganic substances with large polarity differences from polymer materials, resulting in poor compatibility. Large addition amounts can easily lead to agglomeration and a decrease in fiber mechanical properties. Halogenated flame retardants, while having significant flame retardant effects, release corrosive gases during combustion, which does not meet environmental protection requirements.

[0004] Traditional phosphorus-based flame retardants can volatilize or decompose during polyester melt processing, leading to a decrease in flame retardant efficiency and even the generation of corrosive gases. Although polyester fibers have better abrasion resistance than natural fibers, they are still prone to strength reduction due to surface wear in high-frequency friction scenarios. Conventional abrasion-resistant modification techniques mainly involve introducing silica fillers to fill the tiny defects in the material. However, conventional single nano-silica has low chemical affinity with the polyester matrix. During friction, the aggregates formed by silica and the polyethylene terephthalate molecular chains become stress concentration areas due to the incoordination of stress deformation, resulting in poor abrasion resistance. Summary of the Invention

[0005] The purpose of this invention is to provide a flame-retardant modified abrasion-resistant polyester fiber and its preparation method, in order to solve the technical problem that the flame retardancy and abrasion resistance of polyester fibers in the prior art need to be further improved.

[0006] The objective of this invention can be achieved through the following technical solution: a method for preparing flame-retardant modified abrasion-resistant polyester fiber, comprising the following steps:

[0007] S1. Add DDP, nitrogen-modified carbon dot dispersant, terephthalic acid and antimony trioxide to a nitrogen-protected reactor and stir. Raise the temperature to 260-280℃ and the pressure to 320-340kPa to remove water from the system. When no excess water is removed, reduce the pressure to atmospheric pressure and add triphenyl phosphite, anti-hydrolysis agent and ethylene glycol. React for 30-50 minutes to obtain the modified polyethylene terephthalate precursor.

[0008] S2. Raise the temperature of the reaction system to 270-290℃, evacuate to a negative pressure of 0.1MPa, react for 1 hour, and then fill the reaction vessel with nitrogen gas until the melt inside the vessel is squeezed into cold water for quenching to obtain modified polyethylene terephthalate.

[0009] S3. Modified polyethylene terephthalate, ethylene glycol and modified filler are added to a twin-screw extruder for co-extrusion, and then melt-spun on a spinning machine. After winding and stretching, wear-resistant polyester fiber is obtained.

[0010] The synthesis mechanism of modified polyethylene terephthalate is as follows:

[0011]

[0012] In the formula, R: The asterisk (*) indicates the connection site of R.

[0013] After nitrogen-modified carbon dot dispersant is added to the reactor, the hydroxyl and carboxyl groups on its surface can combine with the carboxyl groups of terephthalic acid and the hydroxyl functional groups of ethylene glycol through hydrogen bonding to form a stable EG / gCDs / DDP dispersion system. Terephthalic acid and ethylene glycol undergo a reversible esterification reaction under high temperature and high pressure to generate diethyl terephthalate. In the final polycondensation stage, a high vacuum is drawn to reduce the partial pressure of ethylene glycol and drive the equilibrium towards high molecular weight polyethylene terephthalate. The phosphorus-containing heterocyclic oligomer intermediate of DDP undergoes transesterification and polycondensation reaction with diethyl terephthalate, incorporating the phosphorus-containing heterocyclic structure into the polyethylene terephthalate backbone.

[0014] Further, in step S1, the mass ratio of DDP, nitrogen-modified carbon dispersant, terephthalic acid, antimony trioxide, triphenyl phosphite, antihydrolysis agent, and ethylene glycol is 8:1:700:0.7:1.4:2.1:314; the antihydrolysis agent is antihydrolysis agent 5500; in step S3, the mass ratio of modified polyethylene terephthalate, ethylene glycol, and modified filler is 80-90:5-15:1-3; the temperatures of each section of the twin-screw extruder from the feed section to the die head are 240℃, 260℃, 270℃, 280℃, and 265℃ respectively; the screw speed is 70-90 r / min; the spinning temperature of the spinning machine is 265-280℃, and the spinning speed is 800-1000 m / min.

[0015] In step S1, the preparation method of the nitrogen-modified carbon dot dispersant is as follows:

[0016] A1. Add gelatin and deionized water to a beaker, raise the temperature to 60-80℃, add tetrazolium, stir for 30-60 minutes to obtain a mixed solution;

[0017] A2. Transfer the mixed solution to a high-pressure reactor, raise the temperature to 160-200℃, react for 8-12 hours, and then perform post-treatment to obtain nitrogen-modified carbon dot dispersant.

[0018] Preparation mechanism of nitrogen-modified carbon dot dispersants:

[0019] High temperatures cause the peptide bonds and carbon chains of gelatin to break, generating small molecular fragments. These fragments condense through reactions such as dehydration and decarboxylation, subsequently undergoing cyclization. The cyclization products then polymerize to form sp. 2 The conjugated aromatic skeleton composed of hybrid carbons eventually forms nano-carbon cores as the carbon chains are gradually carbonized. Tetraazole undergoes heterocyclic cleavage under high temperature and pressure, releasing nitrogen-containing active intermediates. These intermediates combine with unsaturated carbon sites of the carbon core, further introducing nitrogen atoms. Some incompletely carbonized polar groups are retained on the surface of the carbon dots. These groups form hydrogen bonds with water molecules, enabling the carbon dots to be stably dispersed in water, thus obtaining nitrogen-modified carbon dot dispersants.

[0020] Further, in step A1, the ratio of gelatin, deionized water and tetrazolium is 1g:1g:20mL; in step A2, the post-processing steps include: after the reaction is completed, the reaction solution is transferred to a round-bottom flask of a rotary evaporator, the temperature is 40-50℃, the negative pressure is drawn to 0.1MPa, and low-boiling substances are evaporated to obtain nitrogen-modified carbon dot dispersant.

[0021] Furthermore, the modified filler preparation method is as follows: pretreated glass flakes and silica dispersion are added to a three-necked flask, ultrasonically dispersed for 20-30 min, KH-560 solution is added dropwise to the system, the temperature is raised to 60-70℃, the reaction is carried out for 3-4 h, and then post-processed to obtain the modified filler.

[0022] Preparation mechanism of modified fillers:

[0023] Silane coupling agents hydrolyze into silanol groups in solution. Both glass flakes and silica surfaces have a large number of hydroxyl groups. These hydroxyl groups undergo dehydration condensation reactions with silanol groups to form stable covalent bonds, anchoring the silane coupling agent molecules to the surfaces of the two fillers and forming a unified epoxy active layer, thus obtaining the modified filler.

[0024] Furthermore, the pretreated glass flakes are processed as follows: glass flakes and 5wt% hydrochloric acid solution are added to a beaker at a solid-liquid ratio of 1:10, the temperature is raised to 60-80℃, and the mixture is stirred for 2-3 hours. Then, the mixture is washed with deionized water until neutral and dried in a vacuum drying oven at 60-80℃ until constant weight to obtain pretreated glass flakes.

[0025] The synthesis mechanism of pretreated glass flakes is as follows:

[0026] The acidic environment of hydrochloric acid promotes the partial hydrolysis of silica on the surface of glass flakes. The silicon-oxygen bonds in the silicate framework break under acidic conditions, generating more active hydroxyl groups.

[0027] Furthermore, the ratio of the pretreated glass flakes, silica dispersion, and KH-560 solution is 2.5g:20mL:2.5mL; the KH-560 solution is composed of γ-glycidyl etheroxypropyltrimethoxysilane and anhydrous ethanol in a ratio of 1g:45mL:5mL; the silica dispersion is composed of nano-silica and anhydrous ethanol in a ratio of 1g:20mL; the post-treatment method includes: after the reaction is completed, the reaction solution is cooled to room temperature, centrifuged, the precipitate is ultrasonically washed 2-3 times with anhydrous ethanol, the filter cake is dried in a vacuum drying oven at 60-80℃ to constant weight, and ground through a 300-mesh sieve to obtain the modified filler.

[0028] This invention also proposes a flame-retardant modified abrasion-resistant polyester fiber, which is prepared using the above-mentioned method for preparing a flame-retardant modified abrasion-resistant polyester fiber.

[0029] The present invention has the following beneficial effects:

[0030] 1. In this invention, during combustion, the phosphorus element in DDP catalyzes the dehydration and cyclization reaction of the polyethylene terephthalate (PET) molecular chain, promoting the formation of a dense char layer. This char layer provides heat and oxygen insulation, preventing further combustion of the matrix and reducing molten dripping. At high temperatures, the phosphorus-oxygen free radicals generated by the decomposition of DDP can capture active free radicals in the combustion reaction, interrupting the combustion chain reaction and inhibiting flame spread. The carboxyl groups of the succinic acid segment combine with the unreacted hydroxyl groups in the PET polycondensation reaction, allowing DDP to be chemically bonded to the PET molecular chain, preventing the flame retardant from migrating and being lost during processing or use, thus improving flame retardant durability. Simultaneously, the phosphorus element in DDP forms a phosphorus-nitrogen synergistic effect with the nitrogen element on the char surface. The nitrogen element promotes the formation of a more stable char layer from the oxidation products of phosphorus, while the inert gases such as ammonia generated by nitrogen decomposition further dilute the combustible gas, significantly improving the flame retardant efficiency.

[0031] 2. The modified filler of this invention is a multi-level flame-retardant system formed by combining glass flakes and silica. The glass flakes are sheet-like structures with a high aspect ratio, which can be oriented axially or radially in the fiber to form a multi-layered physical barrier that blocks the diffusion of oxygen and combustible gases and inhibits direct contact between the flame and the matrix. The nano-silica is a nano-sized particle dispersed in the matrix. At high temperatures, it can act as a carbon nucleus to promote the formation of a finer carbon layer from the modified polyethylene terephthalate, reduce the porosity of the carbon layer, and improve the mechanical strength and wear resistance of the carbon layer. The sheet-like structure of the glass flakes can undergo slight sliding, which transforms sliding friction into rolling friction and reduces the coefficient of friction. The particulate nature of the silica enhances the strength of the matrix and strengthens its wear resistance. The combined effect of both improves the wear resistance of the material.

[0032] 3. This invention utilizes glass flakes and nano-silica modified with silane coupling agents, introducing epoxy groups on the surface. These groups can form chemical bonds or strong interactions with the polyethylene terephthalate (PET) molecular chains, improving the interfacial bonding between the filler and the matrix. This provides physical support at high temperatures, delaying thermal shrinkage and decomposition of the matrix. Furthermore, the inorganic filler itself is heat-resistant, thus improving the overall thermal stability of the material. The succinic acid segments and methylene linkages possess good rotational freedom. When DDP is introduced into the PET molecular chain, the flexible segments can break the dense packing of the original rigid aromatic rings of PET, moderately weakening the interaction forces between molecular chains. This makes the segments more prone to rotation and extension during stretching, providing space for increased elongation at break. Simultaneously, the carboxyl groups can form hydrogen bonds with the amino and hydroxyl groups of the nitrogen-modified gelatin carbon dots, further strengthening the interfacial bonding between the carbon dots and the PET matrix. This allows the nano-dispersed phase to participate more effectively in stress dispersion, reducing localized fracture during stretching. Detailed Implementation

[0033] 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.

[0034] In this application, the gelatin is from Guangzhou Yuanda New Materials Co., Ltd., CAS number 9000-70-8;

[0035] In this application, KH-560 is γ-glycidoxypropyltrimethoxysilane, which is from Shanghai Yihe Biotechnology Co., Ltd., with CAS number 2530-83-8;

[0036] In this application, the glass flakes are from Dacheng County Hengze Anticorrosion Materials Factory, and the item number is 06;

[0037] In this application, DDP is [(6-oxo-6H-dibenzo[c,e][1,2]oxophosphoroxane-6-yl)methyl]succinic acid, which is from Hubei Jianchu Biomedical Co., Ltd., with CAS number 63562-33-4 and purity of 99%.

[0038] Example 1

[0039] This embodiment provides a flame-retardant modified abrasion-resistant polyester fiber and its preparation method, including the following steps:

[0040] S1. Preparation of nitrogen-modified carbon dot dispersant

[0041] Weigh out 10g of gelatin and 20mL of deionized water and add them to a beaker. Raise the temperature to 60℃, add 10g of tetrazolium, and stir for 30min to obtain a mixed solution.

[0042] 20 mL of the mixed solution was transferred to a high-pressure reactor, the temperature was raised to 160 °C, and the reaction was carried out for 8 h. After the reaction was completed, the solution was cooled to room temperature, centrifuged, and filtered through a 0.22 μm needle filter membrane to obtain nitrogen-modified carbon dot dispersant.

[0043] S2. Preparation of modified fillers

[0044] The silica dispersion was prepared by mixing nano silica and anhydrous ethanol at a ratio of 1g:20mL; the KH-560 solution was prepared by mixing γ-glycidoxypropyltrimethoxysilane and anhydrous ethanol at a ratio of 1g:45mL:5mL, and set aside.

[0045] Weigh 10g of glass flakes and 100mL of 5wt% hydrochloric acid solution into a beaker, raise the temperature to 60℃, stir for 2h, then wash with deionized water until neutral, and dry in a vacuum drying oven at 60℃ to constant weight to obtain pretreated glass flakes.

[0046] Weigh 25g of pretreated glass flakes and 200mL of silica dispersion and add them to a three-necked flask. Disperse the mixture by sonication for 20min. Add 25mL of KH-560 solution to the system dropwise. Heat the mixture to 60℃ and react for 3h. After the reaction is complete, cool the reaction solution to room temperature and centrifuge. Wash the precipitate twice with anhydrous ethanol by sonication. Place the filter cake in a vacuum drying oven at 60℃ and dry it to constant weight. Grind the filter cake through a 300-mesh sieve to obtain the modified filler.

[0047] S3, Preparation of modified polyethylene terephthalate

[0048] Weigh out: Add 8g DDP, 1g nitrogen-modified carbon dot dispersant, 700g terephthalic acid and 0.7g antimony trioxide into a nitrogen-protected reactor and stir. Raise the temperature to 260℃ and the pressure to 320kPa to remove water from the system. When no excess water is removed, reduce the pressure to atmospheric pressure and add 1.4g triphenyl phosphite, 2.1g anti-hydrolysis agent and 314g ethylene glycol. React for 30min to obtain the modified polyethylene terephthalate precursor.

[0049] The reaction system temperature was raised to 270℃, the vacuum was drawn to a negative pressure of 0.1MPa, the reaction was carried out for 1 hour, and nitrogen gas was introduced into the reactor to expel the melt into cold water for quenching, thus obtaining modified polyethylene terephthalate.

[0050] S4, abrasion-resistant polyester fiber

[0051] 80g of modified polyethylene terephthalate, 5g of ethylene glycol, and 1g of modified filler were added to a twin-screw extruder for co-extrusion. The temperatures of each section from the feed section to the die head of the twin-screw extruder were 240℃, 260℃, 270℃, 280℃, and 265℃, respectively, and the screw speed was 70r / min. Then, the mixture was melt-spun on a spinning machine at a spinning temperature of 265℃ and a spinning speed of 800m / min. After winding and stretching, abrasion-resistant polyester fibers were obtained.

[0052] Example 2

[0053] This embodiment provides a flame-retardant modified abrasion-resistant polyester fiber and its preparation method, including the following steps:

[0054] S1. Preparation of nitrogen-modified carbon dot dispersant

[0055] Weigh out 10g of gelatin and 20mL of deionized water and add them to a beaker. Raise the temperature to 70℃, add 10g of tetrazolium, and stir for 45min to obtain a mixed solution.

[0056] 20 mL of the mixed solution was transferred to a high-pressure reactor, the temperature was raised to 180 °C, and the reaction was carried out for 10 h. After the reaction was completed, the solution was cooled to room temperature, centrifuged, and filtered through a 0.22 μm needle filter membrane to obtain nitrogen-modified carbon dot dispersant.

[0057] S2. Preparation of modified fillers

[0058] The silica dispersion was prepared by mixing nano silica and anhydrous ethanol at a ratio of 1g:20mL; the KH-560 solution was prepared by mixing γ-glycidoxypropyltrimethoxysilane and anhydrous ethanol at a ratio of 1g:45mL:5mL, and set aside.

[0059] Weigh 10g of glass flakes and 100mL of 5wt% hydrochloric acid solution into a beaker, raise the temperature to 70℃, stir for 2.5h, then wash with deionized water until neutral, and dry in a vacuum drying oven at 70℃ to constant weight to obtain pretreated glass flakes.

[0060] Weigh 25g of pretreated glass flakes and 200mL of silica dispersion and add them to a three-necked flask. Disperse the mixture by sonication for 25min. Add 25mL of KH-560 solution to the system dropwise. Heat the mixture to 65℃ and react for 3.5h. After the reaction is complete, cool the reaction solution to room temperature and centrifuge. Wash the precipitate twice with anhydrous ethanol by sonication. Place the filter cake in a vacuum drying oven at 70℃ and dry it to constant weight. Grind the filter cake through a 300-mesh sieve to obtain the modified filler.

[0061] S3, Preparation of modified polyethylene terephthalate

[0062] Weigh out: 8g DDP, 1g nitrogen-modified carbon dot dispersant, 700g terephthalic acid and 0.7g antimony trioxide into a nitrogen-protected reactor and stir. Raise the temperature to 270℃ and the pressure to 330kPa to remove water from the system. When no excess water is removed, reduce the pressure to atmospheric pressure and add 1.4g triphenyl phosphite, 2.1g anti-hydrolysis agent and 314g ethylene glycol. React for 40min to obtain the modified polyethylene terephthalate precursor.

[0063] The reaction system temperature was raised to 280℃, the vacuum was drawn to a negative pressure of 0.1MPa, the reaction was carried out for 1 hour, and nitrogen gas was introduced into the reaction vessel to expel the melt into cold water for quenching, thereby obtaining modified polyethylene terephthalate.

[0064] S4, abrasion-resistant polyester fiber

[0065] 85g of modified polyethylene terephthalate, 10g of ethylene glycol, and 2g of modified filler were added to a twin-screw extruder for co-extrusion. The temperatures of each section from the feed section to the die head of the twin-screw extruder were 240℃, 260℃, 270℃, 280℃, and 265℃, respectively, and the screw speed was 80r / min. Then, the mixture was melt-spun on a spinning machine at a spinning temperature of 270℃ and a spinning speed of 900m / min. After winding and stretching, abrasion-resistant polyester fibers were obtained.

[0066] Example 3

[0067] This embodiment provides a flame-retardant modified abrasion-resistant polyester fiber and its preparation method, including the following steps:

[0068] S1. Preparation of nitrogen-modified carbon dot dispersant

[0069] Weigh out 10g of gelatin and 20mL of deionized water and add them to a beaker. Raise the temperature to 80℃, add 10g of tetrazolium, and stir for 60min to obtain a mixed solution.

[0070] 20 mL of the mixed solution was transferred to a high-pressure reactor, the temperature was raised to 200 °C, and the reaction was carried out for 12 h. After the reaction was completed, the solution was cooled to room temperature, centrifuged, and filtered through a 0.22 μm needle filter membrane to obtain nitrogen-modified carbon dot dispersant.

[0071] S2. Preparation of modified fillers

[0072] The silica dispersion was prepared by mixing nano silica and anhydrous ethanol at a ratio of 1g:20mL; the KH-560 solution was prepared by mixing γ-glycidoxypropyltrimethoxysilane and anhydrous ethanol at a ratio of 1g:45mL:5mL, and set aside.

[0073] Weigh 10g of glass flakes and 100mL of 5wt% hydrochloric acid solution into a beaker, raise the temperature to 80℃, stir for 3h, then wash with deionized water until neutral, and dry in an 80℃ vacuum drying oven to constant weight to obtain pretreated glass flakes.

[0074] Weigh 25g of pretreated glass flakes and 200mL of silica dispersion and add them to a three-necked flask. Disperse the mixture by sonication for 30min. Add 25mL of KH-560 solution dropwise to the system. Heat the mixture to 70℃ and react for 4h. After the reaction is complete, cool the reaction solution to room temperature and centrifuge. Wash the precipitate three times with anhydrous ethanol by sonication. Place the filter cake in an 80℃ vacuum drying oven and dry it to constant weight. Grind the filter cake through a 300-mesh sieve to obtain the modified filler.

[0075] S3, Preparation of modified polyethylene terephthalate

[0076] Weigh out: 8g DDP, 1g nitrogen-modified carbon dot dispersant, 700g terephthalic acid and 0.7g antimony trioxide into a nitrogen-protected reactor and stir. Raise the temperature to 280℃ and the pressure to 340kPa to remove water from the system. When no excess water is removed, reduce the pressure to atmospheric pressure and add 1.4g triphenyl phosphite, 2.1g anti-hydrolysis agent and 314g ethylene glycol. React for 50min to obtain the modified polyethylene terephthalate precursor.

[0077] The reaction system temperature was raised to 290℃, the vacuum was drawn to a negative pressure of 0.1MPa, the reaction was carried out for 1 hour, and nitrogen gas was introduced into the reactor to expel the melt into cold water for quenching, thus obtaining modified polyethylene terephthalate.

[0078] S4, abrasion-resistant polyester fiber

[0079] 90g of modified polyethylene terephthalate, 15g of ethylene glycol, and 3g of modified filler were added to a twin-screw extruder for co-extrusion. The temperatures of each section from the feed section to the die head of the twin-screw extruder were 240℃, 260℃, 270℃, 280℃, and 265℃, respectively, with a screw speed of 90 r / min. Then, the mixture was melt-spun on a spinning machine at a spinning temperature of 280℃ and a spinning speed of 1000 m / min. After winding and stretching, abrasion-resistant polyester fibers were obtained.

[0080] Comparative Example 1

[0081] The difference between this comparative example and Example 3 is that tetrazolium was not added in step S1.

[0082] Comparative Example 2

[0083] The difference between this comparative example and Example 3 is that step S2 is omitted and silica is used instead of the modified filler.

[0084] Comparative Example 3

[0085] The difference between this comparative example and Example 3 is that DDP was not added in step S3.

[0086] Comparative Example 4

[0087] The difference between this comparative example and Example 3 is that nitrogen-modified carbon dot dispersant was not added in step S3.

[0088] Performance testing:

[0089] The flame retardant properties of the polyester fibers prepared in Examples 1-3 and Comparative Examples 1-4 were determined according to the standard FZ / T 50029-2015 "Test Method for Flame Retardant Properties of Synthetic Fiber Raw Material Chips - Oxygen Index Method".

[0090] The elongation at break of the polyester fibers prepared in Examples 1-3 and Comparative Examples 1-4 was determined in accordance with the standard GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments".

[0091] The abrasion resistance of the polyester fibers prepared in Examples 1-3 and Comparative Examples 1-4 was determined according to the standard GB / T 19089-2012 "Determination of abrasion resistance of rubber or plastic coated fabrics - Martindale method".

[0092] The mass loss rate of the thermal stability of the polyester fibers prepared in Examples 1-3 and Comparative Examples 1-4 was determined according to the standard GB / T 33047.1-2016 "Plastic Polymers Thermogravimetric Method (TG) Part 1: General Rules". The specific test results are shown in Table 1.

[0093] Table 1 - Performance Test Data of Samples

[0094] Group Project Oxygen Index / OI Elongation at break / % Quality loss rate / % Abrasion resistance / damage level Example 1 27 35 25 0 Example 2 28 36 23 0 Example 3 28 35 24 0 Comparative Example 1 23 23 33 2 Comparative Example 2 24 26 32 3 Comparative Example 3 21 25 31 2 Comparative Example 4 22 22 30 2

[0095] Data Analysis:

[0096] Comparative analysis of the data in the table above shows that the polyester fiber prepared by this invention has an oxygen index of 28, an elongation at break of 36%, and a mass loss rate of 23%. The abrasion resistance was found to be undamaged in all cases. The examples are superior to the comparative examples, indicating that the modification of polyethylene terephthalate (PET) and the addition of modified fillers in this invention, through the molecular-level chemical flame retardancy of the modified PET and the physical barrier effect of the fillers, achieves the effect of inhibiting combustion and preventing its spread. Furthermore, the combined effect of the lamellar and granular structures of the fillers improves the abrasion resistance of the material.

[0097] Compared with the example, the phosphorus element of DDP forms a phosphorus-nitrogen synergistic effect with the nitrogen element on the carbon dot surface. The nitrogen element can promote the formation of a more stable carbon layer by the oxidation products of phosphorus. At the same time, the inert gases such as ammonia generated by nitrogen decomposition further dilute the combustible gas, which greatly improves the flame retardant efficiency.

[0098] Compared with the examples, Comparative Example 2 has a sheet-like structure with a high aspect ratio. It can be oriented axially or radially in the fiber to form a multi-layered physical barrier that blocks the diffusion of oxygen and combustible gases, inhibits the direct contact between the flame and the matrix, and works together with the granular form of silica to improve the wear resistance of the material.

[0099] Compared with the examples, in Comparative Example 3, the phosphorus element in DDP catalyzes the dehydration and cyclization reaction of the polyethylene terephthalate molecular chain, promoting the formation of a dense carbon layer. This carbon layer provides thermal and oxygen insulation, preventing further combustion of the matrix and improving the flame retardant properties of the material.

[0100] Compared with the examples, in Comparative Example 4, the phosphorus element of DDP forms a phosphorus-nitrogen synergistic effect with the nitrogen element on the carbon dot surface. The nitrogen element can promote the formation of a more stable carbon layer by the oxidation products of phosphorus. At the same time, the inert gases such as ammonia generated by nitrogen decomposition further dilute the combustible gas, which greatly improves the flame retardant efficiency.

[0101] 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 flame-retardant modified abrasion-resistant polyester fiber, characterized in that, Includes the following steps: S1. Add DDP, nitrogen-modified carbon dot dispersant, terephthalic acid and antimony trioxide to a nitrogen-protected reactor and stir. Raise the temperature to 260-280℃ and the pressure to 320-340kPa to remove water from the system. When no excess water is removed, reduce the pressure to atmospheric pressure and add triphenyl phosphite, anti-hydrolysis agent and ethylene glycol. React for 30-50 minutes to obtain the modified polyethylene terephthalate precursor. S2. Raise the temperature of the reaction system to 270-290℃, evacuate to a negative pressure of 0.1MPa, react for 1 hour, and then fill the reaction vessel with nitrogen gas until the melt inside the vessel is squeezed into cold water for quenching to obtain modified polyethylene terephthalate. S3. Modified polyethylene terephthalate, ethylene glycol and modified filler are added to a twin-screw extruder for co-extrusion, and then melt-spun on a spinning machine. After winding and stretching, wear-resistant polyester fiber is obtained. The preparation method of the nitrogen-modified carbon dot dispersant is as follows: A1. Add gelatin and deionized water to a beaker, raise the temperature to 60-80℃, add tetrazolium, stir for 30-60 minutes to obtain a mixed solution; A2. Transfer the mixed solution to a high-pressure reactor, raise the temperature to 160-200℃, react for 8-12 hours, and then perform post-treatment to obtain nitrogen-modified carbon dot dispersant; The modified filler is prepared by adding pretreated glass flakes and silica dispersion into a three-necked flask, ultrasonically dispersing for 20-30 min, adding KH-560 solution dropwise to the system, heating to 60-70℃, reacting for 3-4 h, and then post-processing to obtain the modified filler.

2. The method for preparing flame-retardant modified abrasion-resistant polyester fiber according to claim 1, characterized in that, In step S1, the mass ratio of DDP, nitrogen-modified carbon dot dispersant, terephthalic acid, antimony trioxide, triphenyl phosphite, antihydrolysis agent, and ethylene glycol is 8:1:700:0.7:1.4:2.1:314; the antihydrolysis agent is antihydrolysis agent 5500. In step S3, the mass ratio of modified polyethylene terephthalate, ethylene glycol, and modified filler is 80-90:5-15:1-3; the temperatures of the twin-screw extruder from the feed section to the die head are 240℃, 260℃, 270℃, 280℃, and 265℃ respectively; the screw speed is 70-90 r / min; the spinning temperature of the spinning machine is 265-280℃, and the spinning speed is 800-1000 m / min.

3. The method for preparing flame-retardant modified abrasion-resistant polyester fiber according to claim 1, characterized in that, In step A1, the ratio of gelatin, tetrazolium, and deionized water is 1g:1g:20mL; in step A2, the post-processing steps include: after the reaction is completed, the reaction solution is transferred to a round-bottom flask of a rotary evaporator, the temperature is 40-50℃, the negative pressure is drawn to 0.1MPa, and low-boiling substances are evaporated to obtain nitrogen-modified carbon dot dispersant.

4. The method for preparing flame-retardant modified abrasion-resistant polyester fiber according to claim 1, characterized in that, The pretreated glass flakes are processed as follows: glass flakes and 5wt% hydrochloric acid solution are added to a beaker at a solid-liquid ratio of 1:10, the temperature is raised to 60-80℃, and the mixture is stirred for 2-3 hours. Then, the mixture is washed with deionized water until neutral and dried in a vacuum drying oven at 60-80℃ until constant weight to obtain pretreated glass flakes.

5. The method for preparing flame-retardant modified abrasion-resistant polyester fiber according to claim 4, characterized in that, The ratio of the pretreated glass flakes, silica dispersion, and KH-560 solution is 2.5g:20mL:2.5mL; the KH-560 solution is composed of γ-glycidyl etheroxypropyltrimethoxysilane, anhydrous ethanol, and deionized water in a ratio of 1g:45mL:5mL; the silica dispersion is composed of nano-silica and anhydrous ethanol in a ratio of 1g:20mL; the post-treatment method includes: after the reaction is completed, the reaction solution is cooled to room temperature, centrifuged, the precipitate is ultrasonically washed 2-3 times with anhydrous ethanol, the filter cake is dried in a vacuum drying oven at 60-80℃ to constant weight, and ground through a 300-mesh sieve to obtain the modified filler.

6. A flame-retardant modified abrasion-resistant polyester fiber, characterized in that, The flame-retardant modified abrasion-resistant polyester fiber is prepared by the method for preparing flame-retardant modified abrasion-resistant polyester fiber as described in any one of claims 1-5.

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