Modified polyester fiber for canvas fabric and preparation method thereof

Abstract

This invention discloses a modified polyester fiber for canvas fabric and its preparation method, belonging to the field of polymer materials technology. It mainly addresses the technical problem of how to further improve the flame retardant, abrasion resistance, and flexibility of modified polyester fiber. Specifically, it includes the following components by weight: 100 parts composite polyester, 1-2 parts nanospheres, 5-10 parts modified basalt, and 1-2 parts auxiliary additives. This invention further improves the flame retardant, abrasion resistance, and flexibility of a modified polyester fiber for canvas fabric prepared by using the prepared composite polyester, nanospheres, and modified basalt.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a modified polyester fiber for canvas fabric and its preparation method. Background Technology

[0002] Polyester fiber has advantages such as high strength, good stiffness, dimensional stability and easy processing, and is widely used in the production of canvas fabrics. However, conventional polyester fiber has certain defects. It is difficult to meet the needs of canvas fabrics in outdoor, industrial and other scenarios in terms of flame retardancy, wear resistance and flexibility, which greatly limits its application range.

[0003] Currently, most polyester fibers use ordinary polyester matrix, which has a simple molecular chain structure. When burning, it is easy to melt and drip, and has low char formation efficiency, making it difficult to form a stable flame-retardant barrier and resulting in insufficient safety performance. At the same time, conventional polyester fibers have poor surface abrasion resistance, and are prone to problems such as pilling and damage during long-term friction and bending, affecting the service life of canvas fabrics. In addition, ordinary polyester fibers have high molecular chain regularity and weak chain segment movement ability, and poor fiber crimp recovery and elasticity. The resulting canvas fabrics are stiff and lack comfort, failing to balance strength and softness.

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

[0005] The purpose of this invention is to provide a modified polyester fiber for canvas fabric and its preparation method, which solves the technical problems of insufficient flame retardancy, abrasion resistance and flexibility of modified polyester fibers in the prior art.

[0006] The objective of this invention can be achieved through the following technical solution: a modified polyester fiber for canvas fabric, comprising the following components by weight: 100 parts of composite polyester, 1-2 parts of nanospheres, 5-10 parts of modified basalt and 1-2 parts of auxiliary additives.

[0007] The auxiliary additives comprise the following components by weight: 0.3-0.5 parts antioxidant 1010, 0.5-0.7 parts calcium stearate, and 0.4-0.7 parts ethylene bis-stearamide;

[0008] The preparation method of the composite polyester is as follows: under a nitrogen atmosphere, dimethyl terephthalate and ethylene glycol are added to a reaction vessel, and the temperature is raised to 170-180°C at a rate of 10°C / min. Zinc acetate is then added, and the mixture is stirred at 170-180°C for 2-3 hours. Then, a sodium salt of 5-sulfonyl-1,3-diphthalate di(2-hydroxyethyl) ester is added, and the mixture is stirred for 20-30 minutes. Antimony trioxide is then added, the pressure is reduced to 10 Pa, and the temperature is raised to 270-280°C. The mixture is stirred for another 2-3 hours. After the reaction is completed, the mixture is discharged and dried at 120°C for 5-6 hours to obtain the composite polyester.

[0009]

[0010] Furthermore, the ratio of the amount of dimethyl terephthalate, ethylene glycol, zinc acetate, monosodium salt of 5-sulfo-1,3-diphthalate di(2-hydroxyethyl) ester and antimony trioxide is 100g:68-72g:0.045g:10-12g:0.035g.

[0011] Furthermore, the preparation method of the nanospheres is as follows: branched polyethyleneimine is added to a reaction vessel containing acetonitrile, stirred until completely dissolved, then triethylamine is added, and stirring is continued for 5-10 minutes. The temperature is then raised to 30-40°C, and an acetonitrile solution of hexachlorocyclotriphosphazene is added. The reaction is carried out for 3-4 hours. After the reaction is completed, the product is separated by centrifugation. The product is first washed with deionized water 2-3 times, then washed with acetone 2-3 times, and then placed in a vacuum drying oven and dried at 50°C to constant weight to obtain nanospheres.

[0012]

[0013] In the formula:

[0014]

[0015] Furthermore, the ratio of the branched polyethyleneimine, acetonitrile, triethylamine and hexachlorocyclotriphosphazene acetonitrile solution is 0.2g:40-50mL:2mL:10mL, wherein the mass fraction of the hexachlorocyclotriphosphazene acetonitrile solution is 1.3%.

[0016] Furthermore, the modified basalt is prepared as follows: KH550 is added to a reaction vessel containing anhydrous ethanol and deionized water, and dilute hydrochloric acid is added dropwise to adjust the pH of the solution to 4-5. The mixture is stirred at 300-500 rpm for 30-60 min at 20-30℃. Then, basalt powder is added, and the temperature is raised to 60-70℃ and stirred for 2-4 h. After the reaction is completed, the mixture is centrifuged, and the solid product is washed 3-4 times with anhydrous ethanol. Finally, it is placed in a vacuum drying oven and dried to constant weight at 60-80℃ to obtain modified basalt.

[0017] Furthermore, the ratio of KH550, anhydrous ethanol, deionized water and basalt powder is 1-2g:250-300mL:20-30mL:100g.

[0018] The present invention also proposes a method for preparing modified polyester fibers for canvas fabric, comprising the following steps:

[0019] S1. Add composite polyester, nanospheres, modified basalt and auxiliary additives to a high-speed mixer and mix for 20-30 minutes at 60-70℃ and 400-500rpm. Then add the blend to a twin-screw extruder for melt blending and extrusion. After water cooling, the mixture is drawn into strands and granulated to obtain modified polyester masterbatch.

[0020] S2. Add the modified polyester masterbatch to a melt spinning machine, and after extrusion molding through a spinneret at 275-285℃ and 15-25rpm, cool and solidify it at 20-25℃ with side blowing air at 0.4-0.6m / s, and then wind it at a speed of 800-1200m / min to obtain nascent fibers.

[0021] S3. After the nascent fiber is preheated by rollers at 80-90℃, it is stretched by 3.0-3.8 times by stretching rollers at 100-110℃, then heat-set by setting rollers at 130-140℃, and finally wound into shape at a speed of 3000-3800m / min to obtain a modified polyester fiber for canvas fabric.

[0022] Furthermore, in step S1, the temperatures of the six temperature zones of the twin-screw extruder, set from the feed end toward the die head, are sequentially set to 265°C, 270°C, 270°C, 275°C, 275°C, and 280°C, and the spindle speed of the twin-screw extruder is 200 rpm.

[0023] The present invention has the following beneficial effects:

[0024] 1. The sulfonate structure introduced into the composite polyester of the present invention can promote char formation during combustion and block the transfer of heat and oxygen. The nanospheres are three-dimensional cross-linked polyphosphazene structures with phosphorus-nitrogen synergy. They decompose upon heating to release inert gases and form a dense char layer, exerting a dual flame-retardant effect in both the gas phase and condensed phase. The modified basalt realizes the organicification of inorganic powder through silicon-oxygen covalent bonds, forming a continuous and stable inorganic heat insulation barrier at high temperatures. The three work together to construct a multi-layer protection system of gas phase flame suppression, condensed phase char formation and inorganic heat insulation, which greatly improves the limiting oxygen index of the fiber and gives the canvas fabric excellent flame retardancy.

[0025] 2. The composite polyester of the present invention optimizes the molecular chain arrangement and crystallinity through sulfonate modification, thereby improving the strength and abrasion resistance of the matrix itself. The three-dimensional cross-linked network structure of nanospheres is uniformly dispersed in the polyester matrix, forming rigid abrasion-resistant points and reducing friction loss. After being treated with KH550 silane coupling agent, the modified basalt is tightly bonded to the polyester matrix interface. The inorganic rigid particles uniformly bear external forces and reduce fiber surface wear. The three work together to achieve matrix reinforcement, interface strengthening, and abrasion-resistant point support, significantly improving the fiber abrasion resistance index and making the canvas fabric more wear-resistant and with a longer service life.

[0026] 3. The composite polyester of the present invention, due to the introduction of sulfonate groups, moderately reduces the regularity of the molecular chain, improves the chain segment mobility and flexibility. The nanospheres are nanoscale three-dimensional cross-linked structures, which do not destroy the fiber continuity and provide elastic support. The modified basalt surface grafted with amino organic layer has excellent compatibility with the polyester matrix and avoids stress concentration caused by the agglomeration of inorganic particles. The three work together to achieve molecular chain flexibility, nanoelastic enhancement and interface defect-free, significantly improving the fiber crimp recovery rate and crimp elasticity, so that the canvas fabric has both strength and good soft hand feel. Detailed Implementation

[0027] 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.

[0028] In this application, the sodium salt of 5-sulfonyl-1,3-phthalic acid di(2-hydroxyethyl) ester, CAS No.: 24019-46-3;

[0029] In this application, the basalt powder is selected from Lingshou County Yiran Mineral Products Processing Plant, and the particle size is 1250 mesh.

[0030] In this application, branched polyethyleneimine, CAS No.: 12162002.

[0031] Example 1

[0032] This embodiment provides a method for preparing modified polyester fibers for canvas fabric, including the following steps:

[0033] S1. Preparation of composite polyester

[0034] Under a nitrogen atmosphere, 100g of dimethyl terephthalate and 68g of ethylene glycol were weighed and added to a reaction vessel. The temperature was raised to 170°C at a rate of 10°C / min. Then, 0.045g of zinc acetate was added, and the mixture was stirred at 170°C for 2 hours. Next, 10g of monosodium salt of 5-sulfonyl-1,3-phthalate di(2-hydroxyethyl) ester was added, and the mixture was stirred for 20 minutes. Then, 0.035g of antimony trioxide was added, the pressure was reduced to 10 Pa, and the temperature was raised to 270°C. The mixture was stirred for another 2 hours. After the reaction was completed, the mixture was discharged and dried at 120°C for 5 hours to obtain the composite polyester.

[0035] Under zinc acetate catalysis, dimethyl terephthalate and ethylene glycol undergo transesterification, with the methyl group of dimethyl terephthalate being replaced by the hydroxyl group of ethylene glycol to generate dihydroxyethyl terephthalate. Then, a monosodium salt of 5-sulfon-1,3-diphthalate di(2-hydroxyethyl) ester is added. Under higher temperature and high vacuum conditions and catalysis by antimony trioxide, the monosodium salt of 5-sulfon-1,3-diphthalate di(2-hydroxyethyl) ester and dihydroxyethyl terephthalate undergo polycondensation reaction, forming a long-chain polymer through ester bonds, and finally obtaining polyester polyethylene terephthalate with sulfonate-modified units.

[0036] S2, Preparation of nanospheres

[0037] Weigh 20g of branched polyethyleneimine and add it to a reaction vessel containing 4000mL of acetonitrile. Stir until completely dissolved, then add 200mL of triethylamine and continue stirring for 5min. Heat to 30℃ and add 1000mL of 1.3wt% acetonitrile solution of hexachlorocyclotriphosphazene. React for 3h. After the reaction is complete, centrifuge and separate the product. Wash the product twice with deionized water and twice with acetone. Place it in a vacuum drying oven and dry at 50℃ to constant weight to obtain nanospheres.

[0038] The primary and secondary amines in the branched polyethyleneimine molecule act as nucleophilic sites, attacking the active P-Cl bonds of the P atoms on the six-membered ring of hexachlorocyclotriphosphazene, resulting in a nucleophilic substitution reaction. The HCl generated by the breaking of the P-Cl bonds is neutralized by triethylamine to form triethylamine hydrochloride. At the same time, the P atoms form stable PN covalent bonds with the N atoms of the branched polyethyleneimine. As the PN bonds continue to form, cross-linking polymerization occurs between the multifunctional monomers, forming nanospheres with a three-dimensional cross-linked polyphosphazene network structure.

[0039] S3, Preparation of modified basalt

[0040] Weigh 1g of KH550 and add it to a reaction vessel containing 250mL of anhydrous ethanol and 20mL of deionized water. Add dilute hydrochloric acid dropwise to adjust the pH of the solution to 4. Stir at 300rpm for 30min at 20℃. Then add 100g of basalt powder and heat to 60℃ and stir for 2h. After the reaction is complete, centrifuge and wash the solid product three times with anhydrous ethanol. Finally, place it in a vacuum drying oven and dry it at 60℃ to constant weight to obtain modified basalt.

[0041] In a weakly acidic aqueous solution, the silane coupling agent KH550 undergoes hydrolysis, and its ethoxy groups hydrolyze into highly active silanol groups. Under heating conditions, these silanol groups undergo a dehydration condensation reaction with the silanol groups on the surface of basalt powder to form strong Si-O-Si covalent bonds. This successfully grafts an organic molecular layer with amino functional groups onto the surface of basalt, achieving organic modification of the inorganic powder surface and obtaining modified basalt.

[0042] S4. Preparation of modified polyester masterbatch

[0043] Weigh out 0.3 parts by weight of antioxidant 1010, 0.5 parts by weight of calcium stearate and 0.4 parts by weight of ethylene bis-stearamide and mix them evenly to obtain the auxiliary additive;

[0044] Weigh out 100 parts of composite polyester, 1 part of nanospheres, 5 parts of modified basalt, and 1 part of auxiliary additives by weight and add them to a high-speed mixer. Mix for 20 minutes at 60℃ and 400rpm. Then add the blend to a twin-screw extruder. Set the temperatures of the six temperature zones in the twin-screw extruder from the feed end toward the die head to 265℃, 270℃, 270℃, 275℃, 275℃, and 280℃ respectively. Set the spindle speed to 200rpm. Perform melt blending and extrusion, and obtain modified polyester masterbatch by water cooling, stretching, and pelletizing.

[0045] S5. Prepare a modified polyester fiber for canvas fabric.

[0046] Modified polyester masterbatch is added to a melt spinning machine, and after being extruded through a spinneret at 275°C and 15 rpm, it is cooled and solidified at 20°C with a side blowing air of 0.4 m / s, and then wound at a speed of 800 m / min to obtain nascent fibers.

[0047] The nascent fibers are preheated on an 80°C roller, stretched 3.0 times on a 100°C stretching roller, then heat-set on a 130°C setting roller, and finally wound at a speed of 3000 m / min to obtain a modified polyester fiber for canvas fabric.

[0048] Example 2

[0049] This embodiment provides a method for preparing modified polyester fibers for canvas fabrics, including the following steps:

[0050] S1. Preparation of composite polyester

[0051] Under a nitrogen atmosphere, 100g of dimethyl terephthalate and 70g of ethylene glycol were weighed and added to a reaction vessel. The temperature was increased to 175°C at a rate of 10°C / min. Then, 0.045g of zinc acetate was added, and the mixture was stirred at 175°C for 2.5h. Next, 11g of monosodium salt of 5-sulfonyl-1,3-phthalate di(2-hydroxyethyl) ester was added, and the mixture was stirred for 25min. Then, 0.035g of antimony trioxide was added, the pressure was reduced to 10Pa, and the temperature was increased to 275°C. The mixture was stirred for another 2.5h. After the reaction was completed, the mixture was discharged and dried at 120°C for 5.5h to obtain the composite polyester.

[0052] S2, Preparation of nanospheres

[0053] Weigh 20g of branched polyethyleneimine and add it to a reaction vessel containing 4500mL of acetonitrile. Stir until completely dissolved, then add 200mL of triethylamine and continue stirring for 8min. Heat to 35℃ and add 1000mL of 1.3wt% acetonitrile solution of hexachlorocyclotriphosphazene. React for 3.5h. After the reaction is complete, centrifuge and wash the product twice with deionized water and twice with acetone. Place it in a vacuum drying oven and dry at 50℃ to constant weight to obtain nanospheres.

[0054] S3, Preparation of modified basalt

[0055] Weigh 1.5g of KH550 and add it to a reaction vessel containing 275mL of anhydrous ethanol and 25mL of deionized water. Add dilute hydrochloric acid dropwise to adjust the pH of the solution to 4.5. Stir at 400rpm for 45min at 25℃. Then add 100g of basalt powder and heat to 65℃ and stir for 3h. After the reaction is complete, centrifuge and wash the solid product three times with anhydrous ethanol. Finally, place it in a vacuum drying oven and dry it at 70℃ to constant weight to obtain modified basalt.

[0056] S4. Preparation of modified polyester masterbatch

[0057] Weigh out 0.4 parts by weight of antioxidant 1010, 0.6 parts by weight of calcium stearate and 0.5 parts by weight of ethylene bis-stearamide and mix them evenly to obtain the auxiliary additive;

[0058] Weigh out 100 parts of composite polyester, 1.5 parts of nanospheres, 7 parts of modified basalt, and 1.5 parts of auxiliary additives by weight and add them to a high-speed mixer. Mix for 25 minutes at 65°C and 450 rpm. Then add the blend to a twin-screw extruder. The twin-screw extruder has six temperature zones set from the feed end toward the die head, with temperatures of 265°C, 270°C, 270°C, 275°C, 275°C, and 280°C respectively. The spindle speed is 200 rpm. Melt-blend extrusion is performed, followed by water cooling, stretching, and pelletizing to obtain modified polyester masterbatch.

[0059] S5. Prepare a modified polyester fiber for canvas fabric.

[0060] Modified polyester masterbatch is added to a melt spinning machine, and after being extruded through a spinneret at 280°C and 20 rpm, it is cooled and solidified at 20°C with a side blowing air of 0.5 m / s, and then wound at a speed of 1000 m / min to obtain nascent fibers.

[0061] The nascent fibers are preheated on an 85°C roller, stretched 3.4 times on a 105°C stretching roller, then heat-set on a 135°C setting roller, and finally wound at a speed of 3400 m / min to obtain a modified polyester fiber for canvas fabric.

[0062] Example 3

[0063] This embodiment provides a method for preparing modified polyester fibers for canvas fabrics, including the following steps:

[0064] S1. Preparation of composite polyester

[0065] Under a nitrogen atmosphere, 100g of dimethyl terephthalate and 72g of ethylene glycol were weighed and added to a reaction vessel. The temperature was raised to 180°C at a rate of 10°C / min. Then, 0.045g of zinc acetate was added. After stirring at 180°C for 3 hours, 12g of monosodium salt of 5-sulfonyl-1,3-phthalate di(2-hydroxyethyl) ester was added. After stirring for 30 minutes, 0.035g of antimony trioxide was added. The pressure was reduced to 10 Pa, and the temperature was raised to 280°C. Stirring was continued for 3 hours. After the reaction was completed, the product was discharged and dried at 120°C for 6 hours to obtain the composite polyester.

[0066] S2, Preparation of nanospheres

[0067] Weigh 20g of branched polyethyleneimine and add it to a reaction vessel containing 5000mL of acetonitrile. Stir until completely dissolved, then add 200mL of triethylamine and continue stirring for 10min. Heat to 40℃ and add 1000mL of 1.3wt% acetonitrile solution of hexachlorocyclotriphosphazene. React for 4h. After the reaction is complete, centrifuge and separate the product. Wash the product three times with deionized water and then three times with acetone. Place it in a vacuum drying oven and dry it at 50℃ to constant weight to obtain nanospheres.

[0068] S3, Preparation of modified basalt

[0069] Weigh 2g of KH550 and add it to a reaction vessel containing 300mL of anhydrous ethanol and 30mL of deionized water. Add dilute hydrochloric acid dropwise to adjust the pH of the solution to 5. Stir at 500rpm for 60min at 30℃. Then add 100g of basalt powder and heat to 70℃ and stir for 4h. After the reaction is complete, centrifuge and wash the solid product 4 times with anhydrous ethanol. Finally, place it in a vacuum drying oven and dry it at 80℃ to constant weight to obtain modified basalt.

[0070] S4. Preparation of modified polyester masterbatch

[0071] Weigh out 0.5 parts of antioxidant 1010, 0.7 parts of calcium stearate and 0.7 parts of ethylene bis-stearamide by weight and mix them evenly to obtain the auxiliary additive;

[0072] Weigh out 100 parts of composite polyester, 2 parts of nanospheres, 10 parts of modified basalt, and 2 parts of auxiliary additives by weight and add them to a high-speed mixer. Mix at 70℃ and 500rpm for 30 minutes. Then add the blend to a twin-screw extruder. The twin-screw extruder has 6 temperature zones set from the feed end to the die head, with the temperatures set sequentially to 265℃, 270℃, 270℃, 275℃, 275℃, and 280℃. The spindle speed is 200rpm. Melt blend extrusion is performed, followed by water cooling, stretching, and pelletizing to obtain modified polyester masterbatch.

[0073] S5. Prepare a modified polyester fiber for canvas fabric.

[0074] Modified polyester masterbatch is added to a melt spinning machine, and after being extruded through a spinneret at 285°C and 25 rpm, it is cooled and solidified at 25°C with a side blowing air of 0.6 m / s, and then wound at a speed of 1200 m / min to obtain nascent fibers.

[0075] The nascent fibers are preheated on a 90°C roller, stretched 3.8 times on a 110°C stretching roller, then heat-set on a 140°C setting roller, and finally wound at a speed of 3800 m / min to obtain a modified polyester fiber for canvas fabric.

[0076] Comparative Example 1

[0077] The difference between this comparative example and Example 3 is that step S1 is omitted, and commercially available polyethylene terephthalate is used instead of the composite polyester in step S4.

[0078] Comparative Example 2

[0079] The difference between this comparative example and Example 3 is that step S2 is omitted, and nanospheres are not added in step S4.

[0080] Comparative Example 3

[0081] The difference between this comparative example and Example 3 is that step S3 is omitted, and the modified basalt in step S4 is replaced with the basalt in step S3.

[0082] Performance testing:

[0083] The limiting oxygen index of a canvas fabric woven from modified polyester fibers prepared in Examples 1-3 and Comparative Examples 1-3 was determined according to standard GB / T 5454-1997 "Test for flammability of textiles - oxygen index method".

[0084] Referring to standard GB / T 21196.3-2007 "Textiles - Martindale Method - Determination of Abrasion Resistance of Fabrics - Part 3: Determination of Mass Loss", the abrasion resistance index of a canvas fabric woven from modified polyester fibers prepared in Examples 1-3 and Comparative Examples 1-3 was determined.

[0085] Referring to standard GB / T 14338-2022 "Test Method for Crimping Properties of Short Chemical Fibers", the crimp recovery rate and crimp elasticity of canvas fabric woven from modified polyester fibers prepared in Examples 1-3 and Comparative Examples 1-3 were determined. The specific test results are shown in Table 1 below:

[0086] Table 1 - Performance Test Data of Samples

[0087] Group Project Limiting oxygen index (%) Abrasion resistance index (cycles / mg) Curl recovery rate (%) Curvature elasticity (%) Example 1 29.5 183 91.4 93.7 Example 2 29.8 187 91.5 93.8 Example 3 30.3 192 91.8 94.0 Comparative Example 1 23.4 134 80.1 76.2 Comparative Example 2 18.2 151 72.4 77.7 Comparative Example 3 25.7 108 68.6 72.4

[0088] Data Analysis:

[0089] Comparative analysis of the data in Table 1 above shows that the canvas fabric woven from modified polyester fibers prepared by this invention has a limiting oxygen index of 30.3%, an abrasion resistance index of 192 cycles / mg, a crimp recovery rate of 91.8%, and a crimp elasticity of 94.0%.

[0090] Comparative Example 1 used ordinary polyester instead of the composite polyester of this invention. Lacking the char-forming, reinforcing, and softening effects of the sulfonate structure, the overall performance of the fiber significantly decreased. Its limiting oxygen index was only 23.4%, failing to form a highly efficient flame-retardant char layer; its abrasion resistance index was 134 cycles / mg, indicating insufficient abrasion resistance of the fiber matrix; the crimp recovery rate was 80.1%, and the crimp elasticity was 76.2%, indicating a significant reduction in molecular chain flexibility and resilience. This demonstrates that the composite polyester is the core matrix for improving the flame retardancy, abrasion resistance, and flexibility of the fiber. Its absence prevents it from synergistically interacting with the nanospheres and modified basalt, resulting in overall fiber performance far inferior to the product of this invention.

[0091] Comparative Example 2, without the addition of the phosphorus-nitrogen three-dimensional cross-linked nanospheres of the present invention, lost its gas-phase flame retardant, wear-resistant support, and elastic reinforcement functions, resulting in a significant deterioration of the key properties of the fiber. Its limiting oxygen index was only 18.2%, and the flame retardant effect was greatly reduced; the wear resistance index was 151 cycles / mg, and the lack of rigid wear-resistant points led to an increase in friction loss; the crimp recovery rate was 72.4%, and the crimp elasticity rate was 77.7%, indicating insufficient elastic support for the fiber. This shows that the nanospheres simultaneously undertake the functions of flame retardancy, wear resistance, and elasticity enhancement in the synergistic system. Without them, the multi-layer protection and reinforcement structure fails, and the various properties of the fiber deteriorate significantly.

[0092] Comparative Example 3 used unmodified basalt, resulting in poor interfacial bonding between inorganic particles and the polyester matrix, and easy agglomeration, leading to the most significant decline in fiber performance. Its limiting oxygen index was 25.7%, failing to form a continuous inorganic insulation layer; the abrasion resistance index was only 108 cycles / mg, with particle shedding exacerbating fiber surface wear; the crimp recovery rate was 68.6%, and the crimp elasticity was 72.4%, with stress concentration severely damaging fiber flexibility. This proves that modified basalt is the key to interfacial strengthening and performance enhancement, while unmodified treatment completely destroys the synergistic system, causing the fiber's flame retardancy, abrasion resistance, and flexibility to fail to meet the application requirements.

[0093] 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 modified polyester fiber for canvas fabric, characterized in that, It includes the following components by weight: 100 parts composite polyester, 1-2 parts nanospheres, 5-10 parts modified basalt and 1-2 parts auxiliary additives; The preparation method of the composite polyester is as follows: under a nitrogen atmosphere, dimethyl terephthalate and ethylene glycol are added to a reaction vessel, and the temperature is raised to 170-180°C at a rate of 10°C / min. Zinc acetate is then added, and the mixture is stirred at 170-180°C for 2-3 hours. Then, a sodium salt of 5-sulfonyl-1,3-diphthalate di(2-hydroxyethyl) ester is added, and the mixture is stirred for 20-30 minutes. Antimony trioxide is then added, the pressure is reduced to 10 Pa, and the temperature is raised to 270-280°C. The mixture is stirred for another 2-3 hours. After the reaction is completed, the mixture is discharged and dried at 120°C for 5-6 hours to obtain the composite polyester.

2. The modified polyester fiber for canvas fabric according to claim 1, characterized in that, The ratio of dimethyl terephthalate, ethylene glycol, zinc acetate, monosodium salt of 5-sulfo-1,3-diphthalate di(2-hydroxyethyl) ester and antimony trioxide is 100g:68-72g:0.045g:10-12g:0.035g.

3. The modified polyester fiber for canvas fabric according to claim 1, characterized in that, The preparation method of the nanospheres is as follows: branched polyethyleneimine is added to a reaction vessel containing acetonitrile and stirred until completely dissolved. Then, triethylamine is added and stirred for 5-10 minutes. The temperature is raised to 30-40°C, and an acetonitrile solution of hexachlorocyclotriphosphazene is added. The reaction is carried out for 3-4 hours. After the reaction is completed, the product is separated by centrifugation. The product is washed 2-3 times with deionized water and then 2-3 times with acetone. It is then placed in a vacuum drying oven and dried at 50°C to constant weight to obtain nanospheres.

4. The modified polyester fiber for canvas fabric according to claim 3, characterized in that, The ratio of the branched polyethyleneimine, acetonitrile, triethylamine and hexachlorocyclotriphosphazene acetonitrile solution is 0.2g:40-50mL:2mL:10mL, wherein the mass fraction of the hexachlorocyclotriphosphazene acetonitrile solution is 1.3%.

5. The modified polyester fiber for canvas fabric according to claim 1, characterized in that, The modified basalt is prepared as follows: KH550 is added to a reaction vessel containing anhydrous ethanol and deionized water, and dilute hydrochloric acid is added dropwise to adjust the pH of the solution to 4-5. The mixture is stirred at 300-500 rpm for 30-60 minutes at 20-30℃. Basalt powder is then added, and the temperature is raised to 60-70℃ and stirred for 2-4 hours. After the reaction is completed, the mixture is centrifuged, and the solid product is washed 3-4 times with anhydrous ethanol. Finally, it is placed in a vacuum drying oven and dried to constant weight at 60-80℃ to obtain modified basalt.

6. The modified polyester fiber for canvas fabric according to claim 5, characterized in that, The ratio of KH550, anhydrous ethanol, deionized water and basalt powder is 1-2g:250-300mL:20-30mL:100g.

7. A method for preparing modified polyester fiber for canvas fabric according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Add composite polyester, nanospheres, modified basalt and auxiliary additives to a high-speed mixer and mix for 20-30 minutes at 60-70℃ and 400-500rpm. Then add the blend to a twin-screw extruder for melt blending and extrusion. After water cooling, the mixture is drawn into strands and granulated to obtain modified polyester masterbatch. S2. Add the modified polyester masterbatch to a melt spinning machine, and after extrusion molding through a spinneret at 275-285℃ and 15-25rpm, cool and solidify it at 20-25℃ with side blowing air at 0.4-0.6m / s, and then wind it at a speed of 800-1200m / min to obtain nascent fibers. S3. After the nascent fiber is preheated by rollers at 80-90℃, it is stretched by 3.0-3.8 times by stretching rollers at 100-110℃, then heat-set by setting rollers at 130-140℃, and finally wound into shape at a speed of 3000-3800m / min to obtain a modified polyester fiber for canvas fabric.

8. The method for preparing modified polyester fiber for canvas fabric according to claim 7, characterized in that, In step S1, the temperatures of the six temperature zones of the twin-screw extruder, set from the feed end toward the die head, are sequentially set to 265°C, 270°C, 270°C, 275°C, 275°C, and 280°C, and the spindle speed of the twin-screw extruder is 200 rpm.

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