A high flame-retardant polyester composite material and its preparation method

Abstract

This invention relates to the field of polymer composite materials technology, and discloses a highly flame-retardant polyester composite material and its preparation method. The invention introduces dual phosphorus flame-retardant groups through copolymerization of phosphate flame-retardant monomers with terephthalic acid, isophthalic acid, and ethylene glycol, and simultaneously introduces dual antibacterial groups of guanidine and pyridinium salts through copolymerization of guanidine-pyridinium salts with the polyester matrix, thus preparing a polyester composite material with both high flame-retardant and antibacterial properties.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, specifically to a high flame-retardant polyester composite material and its preparation method. Background Technology

[0002] Polyethylene terephthalate (PET), a widely used thermoplastic polyester resin, is extensively used in textiles, packaging materials, electronics, automotive interiors, and building materials due to its excellent mechanical properties, good processability, chemical resistance, and dimensional stability. However, ordinary PET is a flammable material, and during combustion, it exhibits severe dripping, easily igniting surrounding combustibles and causing fires to spread. To address the flame retardancy issue of PET, current technologies mainly employ blending with flame retardants. However, blending methods suffer from poor compatibility between the flame retardant and the matrix, easy migration and precipitation, and high addition amounts can degrade the material's mechanical properties. On the other hand, with increasing health awareness and frequent public health emergencies, the antibacterial functionalization of polyester materials has become a research hotspot. PET materials have poor surface hydrophilicity, making them easy for bacteria to adhere and multiply, posing a risk of cross-contamination in medical equipment, public facilities, food contact materials, and textiles. In existing technologies, antibacterial modification typically involves adding inorganic antibacterial agents such as silver-based and zinc-based agents. However, inorganic antibacterial agents have poor compatibility with the polyester matrix, are prone to aggregation, and negatively impact mechanical properties and transparency. Furthermore, existing technologies often only target a single property for modification or employ simple physical blending to simultaneously add flame retardants and antibacterial agents, making it difficult to achieve uniform dispersion and synergistic effects of the two functional groups within the polyester matrix. Therefore, developing a polyester composite material that combines highly efficient flame retardant and antibacterial properties, with stable bonding between the functional groups and the polyester matrix, has significant application value and market potential. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a highly flame-retardant polyester composite material and its preparation method. The polyester composite material prepared by this invention possesses both excellent flame-retardant and antibacterial properties.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a high flame-retardant polyester composite material, comprising the following steps: Step 1: Add 15-15.8g of terephthalic acid, 0.83-1.67g of isophthalic acid, 6.2-6.8g of ethylene glycol, and 3-3.3g of phosphate flame retardant monomer to the polymerization reactor. Under nitrogen protection, heat to 230-240℃ and react at atmospheric pressure for 2-3 hours. When the amount of water distilled reaches 90%-95% of the theoretical value, the esterification reaction is complete. Step 2: Add tetrabutyl titanate catalyst and 1.5-1.7g of guanidinopyridinium salt to the polymerization reactor, along with trimethyl phosphate heat stabilizer. Turn on the vacuum system and reduce the pressure to 2000-4000Pa within 25-35 minutes. Raise the temperature to 250-260℃ and react for 0.5-1 hour. Continue to reduce the pressure to 50-100Pa and continue the reaction for 2-4 hours. Once the polycondensation reaction is complete, turn off the vacuum system and introduce nitrogen to break the vacuum. Extrude the melt through a template, cool it with water, pelletize it, and vacuum dry it to obtain a high flame-retardant polyester composite material.

[0005] Preferably, the amount of the tetrabutyl titanate catalyst is 0.005%-0.01% of the mass of terephthalic acid, and the amount of the trimethyl phosphate heat stabilizer is 0.001%-0.003% of the mass of terephthalic acid.

[0006] Preferably, the phosphate flame retardant monomer is prepared by the following steps: (1) Add 1.6-2g of pentaerythritol phosphate to 15-25mL of anhydrous dichloromethane solvent, stir to dissolve, add 1.08-1.34g of triethylamine acid binder, purge with nitrogen for protection, cool to 0-4℃ in an ice-water bath, add a mixed solution of 1.91-2.39g of 4-formylbenzenesulfonyl chloride and 10-15mL of anhydrous dichloromethane dropwise, after the addition is complete, react for 1-1.5h, raise the temperature to 20-25℃ and continue the reaction for 2.5-3.5h, after the reaction is complete, extract with deionized water, remove the solvent by rotary evaporation of the organic phase, and dry under vacuum to obtain intermediate 1; (2) Under a nitrogen atmosphere, add 3.26-3.7 g of intermediate 1 to 20-30 mL of anhydrous methanol solvent, stir to dissolve, and then add dropwise a mixed solution of 1.51-1.71 g of 3,5-di(hydroxymethyl)aniline and 8-12 mL of anhydrous methanol. After the addition is complete, react at 25-35 °C for 2-4 h. After the reaction is complete, remove the solvent by rotary evaporation to obtain intermediate 2; (3) Under a nitrogen atmosphere, add 4.66-5g of intermediate 2 and 0.05-0.1g of triethylamine catalyst to 20-30mL of anhydrous tetrahydrofuran solvent, stir and mix, and add dropwise 1.4-1.5g of diethyl phosphite and 10-12mL of anhydrous tetrahydrofuran solution. After the addition is complete, react at 22-28℃ for 6-8h. After the reaction is complete, remove the solvent by rotary evaporation, wash and vacuum dry to obtain the phosphate flame retardant monomer.

[0007] Preferably, the dropping time of the mixed solution of 4-formylbenzenesulfonyl chloride and anhydrous dichloromethane in step (1) is 10-15 min.

[0008] Preferably, the dropping time of the mixed solution of 3,5-di(hydroxymethyl)aniline and anhydrous methanol in step (2) is 5-10 min.

[0009] Preferably, the guanidinopyridinium salt is prepared by the following steps: S1. Under a nitrogen atmosphere, add 6-9 mL of deionized water and 18-27 mL of anhydrous ethanol to a reaction flask as solvents, add 0.8-1.2 g of polyhexamethylene guanidine, stir to dissolve, adjust the pH value with triethylamine to obtain a polyhexamethylene guanidine solution, dissolve 0.6-0.9 g of 4-(4-chlorobutyl)pyridine in a mixed solvent of 6-8 mL of anhydrous ethanol and 2-4 mL of deionized water to obtain a 4-(4-chlorobutyl)pyridine solution, add the 4-(4-chlorobutyl)pyridine solution dropwise to the polyhexamethylene guanidine solution over a period of 8-14 min, and after the addition is complete, heat to 50-70 °C and react for 8-10 h. After the reaction is complete, remove the solvent by rotary evaporation, precipitate by adding anhydrous diethyl ether, filter, wash, dialyze in deionized water, and freeze-dry to obtain a guanidine pyridine intermediate. S2. Add 1-1.5 g of guanidinopyridine intermediate to 15-20 mL of anhydrous acetonitrile solvent, stir to dissolve, and add dropwise a mixed solution of 0.59-0.89 g of 2-(2-bromoethoxy)ethanol and 6-8 mL of anhydrous acetonitrile. After the addition is complete, heat to 55-65℃ and react for 10-12 h. After the reaction is complete, remove the solvent by rotary evaporation, pour in anhydrous diethyl ether to precipitate, filter, wash, dialyze in deionized water, and freeze-dry to obtain guanidinopyridine onium salt.

[0010] Preferably, the pH value in S1 is 8-9.

[0011] This invention provides a high flame-retardant polyester composite material prepared by the method described above.

[0012] In summary, this application includes at least one of the following beneficial technical effects: This invention introduces a dual phosphorus flame-retardant group by copolymerizing a phosphate flame-retardant monomer with terephthalic acid, isophthalic acid, and ethylene glycol, and simultaneously introduces dual antibacterial groups of guanidine and pyridinium salts by copolymerizing a guanidine pyridinium salt with a polyester matrix, thus preparing a polyester composite material with both high flame-retardant and antibacterial properties.

[0013] The phosphate groups in the phosphate ester flame-retardant monomer decompose upon heating to generate polyphosphoric acid, which catalyzes the dehydration of the polyester matrix into char, forming a dense, expanded char layer on the material surface. This char layer provides heat insulation, oxygen barrier, and prevents the escape of combustible gases, acting as a condensed-phase flame retardant. Simultaneously, the decomposition of the phosphate ester releases phosphorus-containing free radicals, which capture free radicals in the combustion chain reaction, interrupting the chain reaction and exerting a gas-phase flame-retardant effect. The nitrogen-containing portion decomposes to release non-combustible gases such as ammonia, diluting the concentration of combustible gases and causing the char layer to expand, further enhancing the heat insulation and oxygen barrier effects. Both components are covalently embedded in the polyester side groups, facilitating combustion. It exerts a synergistic flame-retardant effect; both the guanidinium group and the pyridinium salt in guanidinopyridinium salt are positively charged, while the bacterial cell membrane surface is negatively charged. When the material surface comes into contact with bacteria, the positively charged guanidinium group and pyridinium salt bind to the negatively charged bacterial cell membrane through electrostatic adsorption, insert into the cell membrane, destroy the integrity and permeability of the cell membrane, and cause leakage of intracellular substances, thereby killing the bacteria; guanidinopyridinium salt is covalently embedded in the polyester backbone through copolymerization reaction, and the antibacterial group is fixed in the polymer matrix and will not migrate or precipitate, thus exhibiting excellent antibacterial durability. Attached Figure Description

[0014] Figure 1 It is the synthetic reaction formula for phosphate ester flame retardant monomers.

[0015] Figure 2 It is the synthetic reaction formula for guanidinopyridinium salt. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0017] To better understand the above technical solutions, the following will provide a detailed description of the technical solutions in conjunction with the accompanying drawings and specific embodiments.

[0018] Example 1 (1) Add 1.6 g of pentaerythritol phosphate to 15 mL of anhydrous dichloromethane solvent, stir to dissolve, add 1.08 g of triethylamine acid binder, purge with nitrogen for protection, cool to 0 °C in an ice-water bath, add a mixed solution of 1.91 g of 4-formylbenzenesulfonyl chloride and 10 mL of anhydrous dichloromethane dropwise over 10 min, after which react for 1 h, raise the temperature to 20 °C and continue the reaction for 2.5 h, after which extract with deionized water, remove the solvent by rotary evaporation of the organic phase, and dry under vacuum to obtain intermediate 1; (2) Under a nitrogen atmosphere, 3.26 g of intermediate 1 was added to 20 mL of anhydrous methanol solvent and stirred to dissolve. A mixed solution of 1.51 g of 3,5-di(hydroxymethyl)aniline and 8 mL of anhydrous methanol was added dropwise over a period of 5 min. After the addition was complete, the reaction was carried out at 25 °C for 2 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain intermediate 2. (3) Under a nitrogen atmosphere, 4.66 g of intermediate 2 and 0.05 g of triethylamine catalyst were added to 20 mL of anhydrous tetrahydrofuran solvent and stirred. A mixed solution of 1.4 g of diethyl phosphite and 10 mL of anhydrous tetrahydrofuran was then added dropwise. After the addition was complete, the reaction was carried out at 22 °C for 6 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed and dried under vacuum to obtain the phosphate flame-retardant monomer. The synthesis reaction formula is as follows: Figure 1 As shown; (4) Under a nitrogen atmosphere, 6 mL of deionized water and 18 mL of anhydrous ethanol were added to the reaction flask as solvents. 0.8 g of polyhexamethylene guanidine was added and stirred to dissolve. The pH was adjusted to 8 with triethylamine to obtain a polyhexamethylene guanidine solution. 0.6 g of 4-(4-chlorobutyl)pyridine was dissolved in a mixed solvent of 6 mL of anhydrous ethanol and 2 mL of deionized water to obtain a 4-(4-chlorobutyl)pyridine solution. The 4-(4-chlorobutyl)pyridine solution was added dropwise to the polyhexamethylene guanidine solution over a period of 8 min. After the addition was complete, the temperature was raised to 50 °C and the reaction was carried out for 8 h. After the reaction was completed, the solvent was removed by rotary evaporation, and anhydrous diethyl ether was added to precipitate the product. The product was filtered, washed, dialyzed in deionized water, and then freeze-dried to obtain a guanidine pyridine intermediate. (5) Add 1 g of guanidinopyridine intermediate to 15 mL of anhydrous acetonitrile solvent, stir to dissolve, and add dropwise a mixed solution of 0.59 g of 2-(2-bromoethoxy)ethanol and 6 mL of anhydrous acetonitrile. After the addition is complete, heat to 55 °C and react for 10 h. After the reaction is complete, remove the solvent by rotary evaporation, pour in anhydrous diethyl ether to precipitate, filter, wash, dialyze in deionized water, and freeze-dry to obtain guanidinopyridine onium salt; the synthesis reaction formula is as follows. Figure 2 As shown; (6) Add 15g of terephthalic acid, 0.83g of isophthalic acid, 6.2g of ethylene glycol and 3g of phosphate flame retardant monomer to the polymerization reactor. Under nitrogen protection, heat to 230℃ and react at normal pressure for 2 hours. When the amount of water distilled reaches 90% of the theoretical value, the esterification reaction ends. (7) Add tetrabutyl titanate catalyst and 1.5g of guanidinopyridinium salt to the polymerization reactor, and add trimethyl phosphate heat stabilizer at the same time. The amount of tetrabutyl titanate catalyst is 0.005% of the mass of terephthalic acid, and the amount of trimethyl phosphate heat stabilizer is 0.001% of the mass of terephthalic acid. Turn on the vacuum system, reduce the pressure to 2000Pa within 25min, raise the temperature to 250℃ and react for 0.5h. Continue to reduce the pressure to 50Pa and continue to react for 2h. When the polycondensation reaction is over, turn off the vacuum system, introduce nitrogen to break the vacuum, and extrude the melt through the template, water cool, pelletize and vacuum dry to obtain a high flame retardant polyester composite material.

[0019] Example 2 (1) Add 2g of pentaerythritol phosphate to 25mL of anhydrous dichloromethane solvent, stir to dissolve, add 1.34g of triethylamine acid binder, purge with nitrogen for protection, cool to 4℃ in an ice-water bath, add 2.39g of a mixed solution of 4-formylbenzenesulfonyl chloride and 15mL of anhydrous dichloromethane dropwise over 15min, after which the reaction is completed, and continue to react for 1.5h. Then raise the temperature to 25℃ and continue to react for 3.5h. After the reaction is completed, extract with deionized water, remove the solvent by rotary evaporation of the organic phase, and dry under vacuum to obtain intermediate 1. (2) Under a nitrogen atmosphere, 3.7 g of intermediate 1 was added to 30 mL of anhydrous methanol solvent and stirred to dissolve. A mixed solution of 1.71 g of 3,5-di(hydroxymethyl)aniline and 12 mL of anhydrous methanol was added dropwise over a period of 10 min. After the addition was complete, the reaction was carried out at 35 °C for 4 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain intermediate 2. (3) Under a nitrogen atmosphere, 5 g of intermediate 2 and 0.1 g of triethylamine catalyst were added to 30 mL of anhydrous tetrahydrofuran solvent and stirred. Then, a mixed solution of 1.5 g of diethyl phosphite and 12 mL of anhydrous tetrahydrofuran was added dropwise. After the addition was complete, the reaction was carried out at 28 °C for 8 h. After the reaction was completed, the solvent was removed by rotary evaporation, washed and vacuum dried to obtain the phosphate flame retardant monomer. The synthesis reaction formula is as follows: Figure 1 As shown; (4) Under a nitrogen atmosphere, 9 mL of deionized water and 27 mL of anhydrous ethanol were added to the reaction flask as solvents. 1.2 g of polyhexamethylene guanidine was added and stirred to dissolve. The pH was adjusted to 9 with triethylamine to obtain a polyhexamethylene guanidine solution. 0.9 g of 4-(4-chlorobutyl)pyridine was dissolved in a mixed solvent of 8 mL of anhydrous ethanol and 4 mL of deionized water to obtain a 4-(4-chlorobutyl)pyridine solution. The 4-(4-chlorobutyl)pyridine solution was added dropwise to the polyhexamethylene guanidine solution over a period of 14 min. After the addition was complete, the temperature was raised to 70 °C and the reaction was carried out for 10 h. After the reaction was completed, the solvent was removed by rotary evaporation, and anhydrous diethyl ether was added to precipitate the product. The product was filtered, washed, dialyzed in deionized water, and then freeze-dried to obtain a guanidine pyridine intermediate. (5) Add 1.5 g of guanidinopyridine intermediate to 20 mL of anhydrous acetonitrile solvent, stir to dissolve, and add dropwise a mixed solution of 0.89 g of 2-(2-bromoethoxy)ethanol and 8 mL of anhydrous acetonitrile. After the addition is complete, heat to 65 °C and react for 12 h. After the reaction is complete, remove the solvent by rotary evaporation, pour in anhydrous diethyl ether to precipitate, filter, wash, dialyze in deionized water, and freeze-dry to obtain guanidinopyridine onium salt; the synthesis reaction formula is as follows. Figure 2 As shown; (6) Add 15.8g of terephthalic acid, 1.67g of isophthalic acid, 6.8g of ethylene glycol and 3.3g of phosphate flame retardant monomer to the polymerization reactor. Under nitrogen protection, heat to 240℃ and react at normal pressure for 3 hours. When the amount of water distilled reaches 95% of the theoretical value, the esterification reaction ends. (7) Add tetrabutyl titanate catalyst and 1.7g of guanidinopyridinium salt to the polymerization reactor, and add trimethyl phosphate heat stabilizer at the same time. The amount of tetrabutyl titanate catalyst is 0.01% of the mass of terephthalic acid, and the amount of trimethyl phosphate heat stabilizer is 0.003% of the mass of terephthalic acid. Turn on the vacuum system, reduce the pressure to 4000Pa within 35min, raise the temperature to 260℃ and react for 1h. Continue to reduce the pressure to 100Pa and continue to react for 4h. When the polycondensation reaction is over, turn off the vacuum system, introduce nitrogen to break the vacuum, and extrude the melt through the template, water cool, pelletize and vacuum dry to obtain a high flame retardant polyester composite material.

[0020] Example 3 (1) Add 1.8 g of pentaerythritol phosphate to 20 mL of anhydrous dichloromethane solvent, stir to dissolve, add 1.21 g of triethylamine acid binder, purge with nitrogen for protection, cool to 2 °C in an ice-water bath, add 2.15 g of a mixed solution of 4-formylbenzenesulfonyl chloride and 12 mL of anhydrous dichloromethane dropwise over 12 min, after which the reaction is completed, and continue to react for 1.2 h. Then raise the temperature to 22 °C and continue to react for 3 h. After the reaction is completed, extract with deionized water, remove the solvent by rotary evaporation of the organic phase, and dry under vacuum to obtain intermediate 1. (2) Under a nitrogen atmosphere, 3.48 g of intermediate 1 was added to 25 mL of anhydrous methanol solvent and stirred to dissolve. A mixed solution of 1.61 g of 3,5-di(hydroxymethyl)aniline and 10 mL of anhydrous methanol was added dropwise over 8 min. After the addition was complete, the reaction was carried out at 30 °C for 3 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain intermediate 2. (3) Under a nitrogen atmosphere, 4.83 g of intermediate 2 and 0.08 g of triethylamine catalyst were added to 25 mL of anhydrous tetrahydrofuran solvent and stirred. A mixed solution of 1.45 g of diethyl phosphite and 11 mL of anhydrous tetrahydrofuran was then added dropwise. After the addition was complete, the reaction was carried out at 25 °C for 7 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed and dried under vacuum to obtain the phosphate flame-retardant monomer. The synthesis reaction formula is as follows: Figure 1 As shown; (4) Under a nitrogen atmosphere, add 8 mL of deionized water and 24 mL of anhydrous ethanol to the reaction flask as solvents, add 1 g of polyhexamethylene guanidine, stir to dissolve, adjust the pH to 8.5 with triethylamine to obtain a polyhexamethylene guanidine solution, dissolve 0.75 g of 4-(4-chlorobutyl)pyridine in a mixed solvent of 7 mL of anhydrous ethanol and 3 mL of deionized water to obtain a 4-(4-chlorobutyl)pyridine solution, add the 4-(4-chlorobutyl)pyridine solution dropwise to the polyhexamethylene guanidine solution, the dropwise addition time is 11 min, after the dropwise addition is completed, heat to 60 °C and react for 9 h, after the reaction is completed, remove the solvent by rotary evaporation, pour in anhydrous diethyl ether to precipitate, filter, wash, dialyze in deionized water and freeze dry to obtain guanidine pyridine intermediate; (5) Add 1.25 g of guanidinopyridine intermediate to 18 mL of anhydrous acetonitrile solvent, stir to dissolve, and add dropwise a mixed solution of 0.74 g of 2-(2-bromoethoxy)ethanol and 7 mL of anhydrous acetonitrile. After the addition is complete, heat to 60 °C and react for 11 h. After the reaction is complete, remove the solvent by rotary evaporation, pour in anhydrous diethyl ether to precipitate, filter, wash, dialyze in deionized water, and freeze-dry to obtain guanidinopyridine onium salt; the synthesis reaction formula is as follows. Figure 2 As shown; (6) Add 15.4g of terephthalic acid, 1.25g of isophthalic acid, 6.5g of ethylene glycol and 3.15g of phosphate flame retardant monomer to the polymerization reactor. Under nitrogen protection, heat to 235℃ and react at normal pressure for 2.5h. When the amount of water distilled reaches 92% of the theoretical value, the esterification reaction ends. (7) Add tetrabutyl titanate catalyst and 1.6g of guanidinopyridinium salt to the polymerization reactor, and add trimethyl phosphate heat stabilizer at the same time. The amount of tetrabutyl titanate catalyst is 0.008% of the mass of terephthalic acid, and the amount of trimethyl phosphate heat stabilizer is 0.002% of the mass of terephthalic acid. Turn on the vacuum system, reduce the pressure to 3000Pa within 30min, raise the temperature to 255℃ and react for 0.8h. Continue to reduce the pressure to 80Pa and continue to react for 3h. The polycondensation reaction ends. Turn off the vacuum system, introduce nitrogen to break the vacuum, extrude the melt through the template, water cool, pelletize and vacuum dry to obtain a high flame retardant polyester composite material.

[0021] Example 4 (1) Add 1.6 g of pentaerythritol phosphate to 15 mL of anhydrous dichloromethane solvent, stir to dissolve, add 1.08 g of triethylamine acid binder, purge with nitrogen for protection, cool to 0 °C in an ice-water bath, add a mixed solution of 1.91 g of 4-formylbenzenesulfonyl chloride and 10 mL of anhydrous dichloromethane dropwise over 10 min, after which react for 1 h, raise the temperature to 20 °C and continue the reaction for 2.5 h, after which extract with deionized water, remove the solvent by rotary evaporation of the organic phase, and dry under vacuum to obtain intermediate 1; (2) Under a nitrogen atmosphere, 3.26 g of intermediate 1 was added to 20 mL of anhydrous methanol solvent and stirred to dissolve. A mixed solution of 1.51 g of 3,5-di(hydroxymethyl)aniline and 8 mL of anhydrous methanol was added dropwise over a period of 5 min. After the addition was complete, the reaction was carried out at 25 °C for 2 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain intermediate 2. (3) Under a nitrogen atmosphere, 4.66 g of intermediate 2 and 0.05 g of triethylamine catalyst were added to 20 mL of anhydrous tetrahydrofuran solvent and stirred. A mixed solution of 1.4 g of diethyl phosphite and 10 mL of anhydrous tetrahydrofuran was then added dropwise. After the addition was complete, the reaction was carried out at 22 °C for 6 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed and dried under vacuum to obtain the phosphate flame-retardant monomer. The synthesis reaction formula is as follows: Figure 1 As shown; (4) Under a nitrogen atmosphere, 9 mL of deionized water and 27 mL of anhydrous ethanol were added to the reaction flask as solvents. 1.2 g of polyhexamethylene guanidine was added and stirred to dissolve. The pH was adjusted to 9 with triethylamine to obtain a polyhexamethylene guanidine solution. 0.9 g of 4-(4-chlorobutyl)pyridine was dissolved in a mixed solvent of 8 mL of anhydrous ethanol and 4 mL of deionized water to obtain a 4-(4-chlorobutyl)pyridine solution. The 4-(4-chlorobutyl)pyridine solution was added dropwise to the polyhexamethylene guanidine solution over a period of 14 min. After the addition was complete, the temperature was raised to 70 °C and the reaction was carried out for 10 h. After the reaction was completed, the solvent was removed by rotary evaporation, and anhydrous diethyl ether was added to precipitate the product. The product was filtered, washed, dialyzed in deionized water, and then freeze-dried to obtain a guanidine pyridine intermediate. (5) Add 1.5 g of guanidinopyridine intermediate to 20 mL of anhydrous acetonitrile solvent, stir to dissolve, and add dropwise a mixed solution of 0.89 g of 2-(2-bromoethoxy)ethanol and 8 mL of anhydrous acetonitrile. After the addition is complete, heat to 65 °C and react for 12 h. After the reaction is complete, remove the solvent by rotary evaporation, pour in anhydrous diethyl ether to precipitate, filter, wash, dialyze in deionized water, and freeze-dry to obtain guanidinopyridine onium salt; the synthesis reaction formula is as follows. Figure 2 As shown; (6) Add 15.4g of terephthalic acid, 1.25g of isophthalic acid, 6.5g of ethylene glycol and 3.15g of phosphate flame retardant monomer to the polymerization reactor. Under nitrogen protection, heat to 235℃ and react at normal pressure for 2.5h. When the amount of water distilled reaches 92% of the theoretical value, the esterification reaction ends. (7) Add tetrabutyl titanate catalyst and 1.6g of guanidinopyridinium salt to the polymerization reactor, and add trimethyl phosphate heat stabilizer at the same time. The amount of tetrabutyl titanate catalyst is 0.008% of the mass of terephthalic acid, and the amount of trimethyl phosphate heat stabilizer is 0.002% of the mass of terephthalic acid. Turn on the vacuum system, reduce the pressure to 3000Pa within 30min, raise the temperature to 255℃ and react for 0.8h. Continue to reduce the pressure to 80Pa and continue to react for 3h. The polycondensation reaction ends. Turn off the vacuum system, introduce nitrogen to break the vacuum, extrude the melt through the template, water cool, pelletize and vacuum dry to obtain a high flame retardant polyester composite material.

[0022] Comparative Example 1 The difference between this comparative example and Example 4 is that it does not include steps (1), (2), and (3), and step (6) does not contain phosphate flame retardant monomers.

[0023] Comparative Example 2 The difference between this comparative example and Example 4 is that it does not include steps (4) and (5), and does not contain guanidinium pyridinium salt in step (7).

[0024] The limiting oxygen index of the polyester composite materials in Examples 1-4 and Comparative Examples 1-2 was tested according to GB / T 2406.2-2009; the vertical flammability rating of the polyester composite materials in Examples 1-4 and Comparative Examples 1-2 was tested according to UL94 standard. The test results are shown in Table 1.

[0025] Table 1: Flame retardant performance test.

[0026]

[0027] As shown in Table 1, the polyester composite materials in Examples 1-4 and Comparative Example 2 of the present invention have better flame retardant properties than the polyester composite material in Comparative Example 1.

[0028] According to GB / T 31402-2023, Escherichia coli and Staphylococcus aureus were used as test bacteria to test the antibacterial rate of the polyester composite materials in Examples 1-4 and Comparative Examples 1-2. The test results are shown in Table 2.

[0029] Table 2: Antibacterial performance test.

[0030]

[0031] As shown in Table 2, the polyester composite materials in Examples 1-4 and Comparative Example 1 have better antibacterial properties than the polyester composite material in Comparative Example 2.

[0032] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0033] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0034] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.

Claims

1. A method for preparing a high flame-retardant polyester composite material, characterized in that, Includes the following steps: Step 1: Add 15-15.8g of terephthalic acid, 0.83-1.67g of isophthalic acid, 6.2-6.8g of ethylene glycol, and 3-3.3g of phosphate flame retardant monomer to the polymerization reactor. Under nitrogen protection, heat to 230-240℃ and react at atmospheric pressure for 2-3 hours. When the amount of water distilled reaches 90%-95% of the theoretical value, the esterification reaction is complete. Step 2: Add tetrabutyl titanate catalyst and 1.5-1.7g of guanidinopyridinium salt to the polymerization reactor, along with trimethyl phosphate heat stabilizer. Turn on the vacuum system and reduce the pressure to 2000-4000Pa within 25-35 minutes. Raise the temperature to 250-260℃ and react for 0.5-1 hour. Continue to reduce the pressure to 50-100Pa and continue the reaction for 2-4 hours. Once the polycondensation reaction is complete, turn off the vacuum system and introduce nitrogen to break the vacuum. Extrude the melt through a template, cool it with water, pelletize it, and vacuum dry it to obtain a high flame-retardant polyester composite material.

2. The method for preparing the high flame-retardant polyester composite material according to claim 1, characterized in that, The amount of the tetrabutyl titanate catalyst is 0.005%-0.01% of the mass of terephthalic acid, and the amount of the trimethyl phosphate heat stabilizer is 0.001%-0.003% of the mass of terephthalic acid.

3. The method for preparing the high flame-retardant polyester composite material according to claim 1, characterized in that, The phosphate flame-retardant monomer is prepared by the following steps: (1) Add 1.6-2g of pentaerythritol phosphate to 15-25mL of anhydrous dichloromethane solvent, stir to dissolve, add 1.08-1.34g of triethylamine acid binder, purge with nitrogen for protection, cool to 0-4℃ in an ice-water bath, add a mixed solution of 1.91-2.39g of 4-formylbenzenesulfonyl chloride and 10-15mL of anhydrous dichloromethane dropwise, after the addition is complete, react for 1-1.5h, raise the temperature to 20-25℃ and continue the reaction for 2.5-3.5h, after the reaction is complete, extract with deionized water, remove the solvent by rotary evaporation of the organic phase, and dry under vacuum to obtain intermediate 1; (2) Under a nitrogen atmosphere, add 3.26-3.7 g of intermediate 1 to 20-30 mL of anhydrous methanol solvent, stir to dissolve, and then add dropwise a mixed solution of 1.51-1.71 g of 3,5-di(hydroxymethyl)aniline and 8-12 mL of anhydrous methanol. After the addition is complete, react at 25-35 °C for 2-4 h. After the reaction is complete, remove the solvent by rotary evaporation to obtain intermediate 2; (3) Under a nitrogen atmosphere, add 4.66-5g of intermediate 2 and 0.05-0.1g of triethylamine catalyst to 20-30mL of anhydrous tetrahydrofuran solvent, stir and mix, and add dropwise 1.4-1.5g of diethyl phosphite and 10-12mL of anhydrous tetrahydrofuran solution. After the addition is complete, react at 22-28℃ for 6-8h. After the reaction is complete, remove the solvent by rotary evaporation, wash and vacuum dry to obtain the phosphate flame retardant monomer.

4. The method for preparing the high flame-retardant polyester composite material according to claim 3, characterized in that, In step (1), the mixture of 4-formylbenzenesulfonyl chloride and anhydrous dichloromethane is added dropwise over a time of 10-15 minutes.

5. The method for preparing the high flame-retardant polyester composite material according to claim 3, characterized in that, In step (2), the dropping time of the mixed solution of 3,5-di(hydroxymethyl)aniline and anhydrous methanol is 5-10 min.

6. The method for preparing the high flame-retardant polyester composite material according to claim 1, characterized in that, The guanidinopyridinium salt is prepared by the following steps: S1. Under a nitrogen atmosphere, add 6-9 mL of deionized water and 18-27 mL of anhydrous ethanol to a reaction flask as solvents, add 0.8-1.2 g of polyhexamethylene guanidine, stir to dissolve, adjust the pH value with triethylamine to obtain a polyhexamethylene guanidine solution, dissolve 0.6-0.9 g of 4-(4-chlorobutyl)pyridine in a mixed solvent of 6-8 mL of anhydrous ethanol and 2-4 mL of deionized water to obtain a 4-(4-chlorobutyl)pyridine solution, add the 4-(4-chlorobutyl)pyridine solution dropwise to the polyhexamethylene guanidine solution over a period of 8-14 min, and after the addition is complete, heat to 50-70 °C and react for 8-10 h. After the reaction is complete, remove the solvent by rotary evaporation, precipitate by adding anhydrous diethyl ether, filter, wash, dialyze in deionized water, and freeze-dry to obtain a guanidine pyridine intermediate. S2. Add 1-1.5 g of guanidinopyridine intermediate to 15-20 mL of anhydrous acetonitrile solvent, stir to dissolve, and add dropwise a mixed solution of 0.59-0.89 g of 2-(2-bromoethoxy)ethanol and 6-8 mL of anhydrous acetonitrile. After the addition is complete, heat to 55-65℃ and react for 10-12 h. After the reaction is complete, remove the solvent by rotary evaporation, pour in anhydrous diethyl ether to precipitate, filter, wash, dialyze in deionized water, and freeze-dry to obtain guanidinopyridine onium salt.

7. The method for preparing the high flame-retardant polyester composite material according to claim 6, characterized in that, The pH value of S1 is 8-9.

8. A high flame-retardant polyester composite material prepared by the preparation method of the high flame-retardant polyester composite material as described in any one of claims 1-7.

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