A method for the production of flame-retardant polyester chip composites by ceppa

Abstract

The application relates to the technical field of high polymer materials and flame-retardant polyester modification, in particular to a method for preparing a flame-retardant polyester chip composite material by using CEPPA. The flame-retardant polyester chip composite material comprises a synergistically modified polyester matrix resin, CEPPA, an organic small-molecule functional regulator, a catalyst, an antioxidant and a stabilizer; the synergistically modified polyester matrix resin is a polyester resin obtained by synergistically modifying terephthalic acid and ethylene glycol in a polycondensation reaction process through formation of a dynamic borate ester bond structure by catechol and phenylboronic acid and hydrolytic condensation reaction of gamma-aminopropyl triethoxysilane. The application constructs a molecular network with synergistic action of a dynamic borate ester structure and an organic silicon structure in a polyester matrix, and introduces tannic acid to regulate the polyester molecular structure, so that the dispersion stability and flame-retardant synergistic efficiency of CEPPA in the polyester system are improved, and the thermal stability and mechanical properties of the material are enhanced, and the flame-retardant performance and comprehensive performance are excellent.

Description

Technical Field

[0001] This invention relates to the field of polymer materials and flame-retardant polyester modification technology, specifically to a method for preparing flame-retardant polyester chip composite materials using CEPPA. Background Technology

[0002] Polyethylene terephthalate (PET) polyester materials are widely used in fibers, engineering plastics, electronics, and packaging materials due to their good mechanical properties, chemical resistance, and excellent processing performance. However, the polyester molecule contains a large number of ester groups in its main chain, which easily undergoes thermal decomposition at high temperatures and releases flammable gases, giving it high flammability. This limits its application in fields requiring high flame retardancy.

[0003] Currently, common methods for improving the flame retardant properties of polyester materials mainly include two approaches: additive flame retardants and reactive flame retardants. Among them, reactive phosphorus-based flame retardants have attracted widespread attention because they can be introduced into the polyester molecular chain during polymerization, are not easily migrated, and have good flame retardant stability. CEPPA, or 2-carboxyethylphenylphosphine, is a commonly used reactive phosphorus-based flame retardant monomer. Its molecular structure contains both carboxyl and phosphine groups, allowing it to participate in copolymerization during polyester polycondensation, thereby introducing phosphorus into the polyester molecular chain and improving the flame retardant properties of the material.

[0004] However, in practical applications, simply using CEPPA for flame retardant modification still presents certain problems. For example, the introduction of CEPPA can easily affect the polycondensation reaction process of the polyester system, leading to a decrease in the molecular weight of the polyester and consequently affecting the mechanical properties of the material. Simultaneously, the limited dispersion stability of CEPPA in the polyester system can easily result in a decrease in the thermal stability of the material. Furthermore, the lack of effective structural control methods in flame retardant systems can also affect the formation of the flame-retardant char layer, thus limiting further improvements in flame retardant efficiency.

[0005] Therefore, developing a flame-retardant polyester chip composite material that can achieve synergistic structural regulation during the polyester structure formation process, improve the flame-retardant efficiency of CEPPA, and maintain stable overall material performance, as well as its preparation method, is of great significance for enhancing the application of polyester materials in the field of high-performance flame retardancy. Summary of the Invention

[0006] To overcome the problems of limited flame retardant efficiency improvement, decreased polyester molecular weight, and insufficient overall material stability in CEPPA flame-retardant polyester systems mentioned above, the present invention aims to provide a method for preparing flame-retardant polyester chip composite materials using CEPPA. This invention introduces catechol, phenylboronic acid, and γ-aminopropyltriethoxysilane during the polyester polycondensation reaction to construct a synergistically modified polyester matrix resin with dynamic borate ester bonds and an organosilicon interface structure. Combined with CEPPA as a reactive phosphorus-based flame-retardant monomer and ellagic acid as an organic small-molecule functional regulator, and further combined with catalysts, antioxidants, and stabilizers for composite regulation, a CEPPA flame-retardant polyester chip composite material is prepared. By constructing a polyester molecular network with synergistic dynamic borate ester structure and organosilicon interface structure and introducing ellagic acid for molecular structure regulation, this invention can significantly improve the dispersion stability of CEPPA in the polyester system and enhance the synergistic flame-retardant effect of the material, thereby effectively improving flame retardant performance while maintaining the mechanical and thermal stability of the polyester material.

[0007] The objective of this invention can be achieved through the following technical solutions: A CEPPA flame-retardant polyester chip composite material, comprising the following raw materials in parts by weight: 80-110 parts of synergistically modified polyester matrix resin; 3-15 parts of CEPPA; 0.1-3 parts of organic small molecule functional regulator; 0.01-0.5 parts of catalyst; 0.1-1.0 parts of antioxidant; and 0.05-0.8 parts of stabilizer. The synergistically modified polyester matrix resin is a polyester resin obtained by synergistic modification during the polycondensation reaction of terephthalic acid and ethylene glycol, through the formation of a dynamic borate ester bond structure between catechol and phenylboronic acid, and the subsequent hydrolysis and condensation reaction with γ-aminopropyltriethoxysilane. The organic small molecule functional regulator is ellagic acid.

[0008] Optionally, the synergistically modified polyester matrix resin comprises the following raw materials in parts by weight: 80-110 parts of terephthalic acid; 40-70 parts of ethylene glycol; 0.5-4 parts of catechol; 0.5-4 parts of phenylboronic acid; and 0.5-5 parts of γ-aminopropyltriethoxysilane.

[0009] Optionally, the method for preparing the synergistically modified polyester matrix resin includes the following steps: (1) Terephthalic acid and ethylene glycol are mixed and subjected to esterification reaction to obtain polyester oligomer melt; (2) Add catechol, phenylboronic acid and γ-aminopropyltriethoxysilane to the polyester oligomer melt to react and obtain a synergistic modification reaction system; (3) The synergistic modification reaction system is subjected to polycondensation reaction. After the reaction is completed, the melt is extruded and pelletized to obtain the synergistic modified polyester matrix resin.

[0010] Optionally, the reaction conditions in step (1) are as follows: esterification reaction is carried out at 220-260°C under nitrogen protection, with a stirring speed of 200-400 r / min and a reaction time of 1-3 h.

[0011] Optionally, the reaction conditions in step (2) are as follows: the reaction is carried out at 240-280°C, the stirring speed is 300-600 r / min, and the reaction time is 0.5-2 h.

[0012] Optionally, the reaction conditions for step (3) are as follows: polycondensation reaction is carried out under gradually reduced pressure, with a reaction pressure of 10-200 Pa, a reaction temperature of 250-280 °C, and a reaction time of 1-3 h.

[0013] Optionally, the catalyst is a mixture of antimony trioxide and tetrabutyltitanium in a mass ratio of 1 to 5:1; the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1 to 3:1; and the stabilizer is a mixture of calcium stearate and triphenyl phosphite in a mass ratio of 1 to 4:1.

[0014] Optionally, a method for preparing flame-retardant polyester chip composite material using CEPPA includes the following steps: S1, the synergistically modified polyester matrix resin is added to a melt mixing device and heated and melted to obtain a polyester melt; S2, CEPPA, organic small molecule functional regulators, catalysts, antioxidants and stabilizers are added to the polyester melt and mixed in the molten state to obtain flame-retardant modified polyester melt; S3 involves extruding, cooling, and pelletizing the flame-retardant modified polyester melt to obtain CEPPA flame-retardant polyester chip composite material.

[0015] Optionally, the reaction conditions for step S1 are: melting treatment at 240–270°C, stirring speed of 100–300 r / min, and melting time of 10–30 min; the reaction conditions for step S2 are: mixing reaction at 250–280°C, stirring speed of 200–500 r / min, and reaction time of 20–60 min.

[0016] Optionally, the reaction conditions in step S3 are melt extrusion at 250–280°C, extruder screw speed of 50–200 r / min, and pelletizing after water cooling to obtain flame-retardant polyester chip composite material.

[0017] The beneficial effects of this invention are: This invention introduces a dynamic borate ester bond structure formed by catechol and phenylboronic acid during polyester polycondensation, and utilizes γ-aminopropyltriethoxysilane for hydrolysis and condensation in the reaction system to form an organosilicon structure with interfacial anchoring effect between polyester molecular chains. This constructs a molecular network structure in the polyester matrix with synergistic effects of dynamic and interfacial bond structures. This structure effectively improves the dispersion uniformity of CEPPA in the polyester system and enhances the interaction forces between polyester molecular chains, reducing the adverse effects of CEPPA introduction on the polyester molecular weight and mechanical properties. Furthermore, this invention introduces ellagic acid with a polyphenolic structure as an organic small molecule functional regulator. Its abundant phenolic hydroxyl groups can form multiple hydrogen bonds with the polyester molecular chains and the phosphorus-oxygen structure in CEPPA, promoting the formation of a stable char layer under high-temperature conditions. This effectively inhibits thermal decomposition reactions and improves the charring ability of the material during combustion, thereby significantly improving flame retardant efficiency with lower CEPPA dosage, achieving a synergistic improvement in flame retardant performance, thermal stability, and mechanical properties. Attached Figure Description

[0018] The invention will now be further described with reference to the accompanying drawings.

[0019] Figure 1 The image shows a comparison of the infrared spectra of unmodified polyester matrix resin and synergistically modified polyester matrix resin. Figure 2 A comparison chart of limiting oxygen index test results for samples with different ratios. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the following embodiments. Equivalent adjustments made without departing from the spirit and essence of the present invention should also be considered to fall within the protection scope of the present invention.

[0021] Example 1: The purpose of this example is to verify that, under the limited conditions of each component and reaction condition, the system of the present invention can still form a stable synergistic modified polyester structure and obtain polyester chip material with flame retardant properties.

[0022] S1, Preparation of Synergistically Modified Polyester Matrix Resin 80 parts of terephthalic acid and 40 parts of ethylene glycol were added to a reactor and stirred at 200 r / min under nitrogen protection while the temperature was raised to 220℃ for 1 h to obtain a polyester oligomer melt. Subsequently, 0.5 parts of catechol, 0.5 parts of phenylboronic acid, and 0.5 parts of γ-aminopropyltriethoxysilane were added to the oligomer melt, and the reaction was continued at 240℃ and 300 r / min for 0.5 h to allow catechol and phenylboronic acid to form a dynamic borate ester structure, while γ-aminopropyltriethoxysilane underwent a hydrolysis-condensation reaction. Then, the reaction pressure was gradually reduced to 200 Pa at 250℃ and a polycondensation reaction was carried out for 1 h to obtain a synergistically modified polyester matrix resin. S2, Preparation of flame-retardant polyester melt 80 parts of the synergistically modified polyester matrix resin obtained in step S1 were added to a melt mixing device and stirred and melted at 100 r / min at 240℃ for 10 min; then 3 parts of CEPPA, 0.1 parts of ellagic acid, 0.01 parts of catalyst, 0.1 parts of antioxidant and 0.05 parts of stabilizer were added and stirred and mixed at 200 r / min at 250℃ for 20 min to obtain flame-retardant modified polyester melt; S3, Polyester Chip Preparation The flame-retardant modified polyester melt obtained in step S2 was melt extruded at 250°C with an extruder screw speed of 50 r / min. After water cooling, it was pelletized to obtain CEPPA flame-retardant polyester chip composite material.

[0023] Example 2: The purpose of this example is to verify that, under the recommended median range, the system of the present invention can form a structurally stable synergistic modified polyester network and obtain a flame-retardant polyester chip composite material in which the flame retardant properties and the overall material properties are in the best balance.

[0024] S1, Preparation of Synergistically Modified Polyester Matrix Resin 95 parts of terephthalic acid and 55 parts of ethylene glycol were added to a reactor and stirred at 300 r / min under nitrogen protection while the temperature was raised to 240℃ for esterification for 2 h to obtain a polyester oligomer melt. Subsequently, 2 parts of catechol, 2 parts of phenylboronic acid, and 2.5 parts of γ-aminopropyltriethoxysilane were added to the oligomer melt, and the reaction was continued at 260℃ and 450 r / min for 1 h to allow catechol and phenylboronic acid to form a dynamic borate ester structure, while γ-aminopropyltriethoxysilane underwent a hydrolysis-condensation reaction. Then, the reaction pressure was gradually reduced to 80 Pa at 265℃ and a polycondensation reaction was carried out for 2 h to obtain a synergistically modified polyester matrix resin. Figure 1The infrared spectrum comparison shows that the unmodified polyester matrix exhibits a distinct C=O stretching vibration absorption peak at approximately 1720 cm⁻¹, and typical C–O–C stretching vibration peaks near 1240 cm⁻¹ and 1100 cm⁻¹, indicating that the material possesses typical polyester structural characteristics. The modified material, while retaining the aforementioned polyester characteristic peaks, shows new absorption peaks near approximately 1390 cm⁻¹ and 1330 cm⁻¹, which can be attributed to B–O and B–O–C vibrations, indicating that catechol and phenylboronic acid form a borate ester structure. Simultaneously, the absorption peak near approximately 1100 cm⁻¹ is significantly enhanced, related to the Si–O–Si or Si–O–C structure, indicating that γ-aminopropyltriethoxysilane participates in the reaction and forms an organosilicon structure. These results demonstrate that the synergistic modified structure has been successfully introduced into the polyester matrix. S2, Preparation of flame-retardant polyester melt 95 parts of the synergistically modified polyester matrix resin obtained in step S1 were added to a melt mixing device and stirred and melted at 200 r / min at 255℃ for 20 min; then 8 parts of CEPPA, 1.5 parts of ellagic acid, 0.2 parts of catalyst, 0.5 parts of antioxidant and 0.4 parts of stabilizer were added and stirred and mixed at 350 r / min at 265℃ for 40 min to obtain flame-retardant modified polyester melt. S3, Polyester Chip Preparation The flame-retardant modified polyester melt obtained in step S2 was melt extruded at 265°C with an extruder screw speed of 120 r / min. After water cooling, it was pelletized to obtain CEPPA flame-retardant polyester chip composite material.

[0025] Example 3: The purpose of this example is to verify that, under the upper limits of each component and reaction conditions, the system of the present invention can still stably construct a synergistically modified polyester structure and further improve the flame retardant properties and thermal stability of the material.

[0026] S1, Preparation of Synergistically Modified Polyester Matrix Resin 110 parts of terephthalic acid and 70 parts of ethylene glycol were added to a reactor and esterified at 400 r / min for 3 h under nitrogen protection, with stirring and heating to 260 °C to obtain a polyester oligomer melt. Subsequently, 4 parts of catechol, 4 parts of phenylboronic acid, and 5 parts of γ-aminopropyltriethoxysilane were added to the oligomer melt, and the reaction was continued at 280 °C and 600 r / min for 2 h to form a dynamic borate ester structure between catechol and phenylboronic acid, while γ-aminopropyltriethoxysilane underwent a hydrolysis-condensation reaction. Then, the reaction pressure was gradually reduced to 10 Pa at 280 °C and polycondensation was carried out for 3 h to obtain a synergistically modified polyester matrix resin. S2, Preparation of flame-retardant polyester melt 110 parts of the synergistically modified polyester matrix resin obtained in step S1 were added to a melt mixing device and stirred and melted at 300 r / min at 270℃ for 30 min; then 15 parts of CEPPA, 3 parts of ellagic acid, 0.5 parts of catalyst, 1.0 part of antioxidant and 0.8 parts of stabilizer were added and stirred and mixed at 500 r / min at 280℃ for 60 min to obtain flame-retardant modified polyester melt; S3, Polyester Chip Preparation The flame-retardant modified polyester melt obtained in step S2 was melt extruded at 280°C with an extruder screw speed of 200 r / min. After water cooling, it was pelletized to obtain CEPPA flame-retardant polyester chip composite material.

[0027] Comparative Example 1: The purpose of this comparative example is to verify the effect of simply modifying the polyester matrix by forming dynamic borate ester bonds between catechol and phenylboronic acid on the overall performance and flame retardant synergistic effect of flame-retardant polyester chip composites.

[0028] S1, Preparation of Synergistically Modified Polyester Matrix Resin 95 parts of terephthalic acid and 55 parts of ethylene glycol were added to a reactor and stirred at 300 r / min under nitrogen protection and heated to 240℃ for 2 h to obtain a polyester oligomer melt. Then, 2 parts of catechol and 2 parts of phenylboronic acid were added to the oligomer melt and the reaction was continued at 260℃ and 450 r / min for 1 h to form a dynamic borate ester structure between catechol and phenylboronic acid. Subsequently, the reaction pressure was gradually reduced to 80 Pa at 265℃ and a polycondensation reaction was carried out for 2 h to obtain a single dynamic borate ester modified polyester matrix resin. S2, Preparation of flame-retardant polyester melt 95 parts of the single dynamic borate ester modified polyester matrix resin obtained in step S1 were added to a melt mixing device and stirred and melted at 200 r / min at 255℃ for 20 min; then 8 parts of CEPPA, 1.5 parts of ellagic acid, 0.2 parts of catalyst, 0.5 parts of antioxidant and 0.4 parts of stabilizer were added and stirred and mixed at 350 r / min at 265℃ for 40 min to obtain flame-retardant modified polyester melt; S3, Polyester Chip Preparation The flame-retardant modified polyester melt obtained in step S2 was melt extruded at 265°C with an extruder screw speed of 120 r / min. After water cooling, it was pelletized to obtain CEPPA flame-retardant polyester chip composite material.

[0029] Comparative Example 2: The purpose of this comparative example is to verify the effect of modifying the polyester matrix solely with γ-aminopropyltriethoxysilane on the overall performance and synergistic flame retardant effect of flame-retardant polyester chip composites.

[0030] S1, Preparation of Synergistically Modified Polyester Matrix Resin 95 parts of terephthalic acid and 55 parts of ethylene glycol were added to a reactor and stirred at 300 r / min under nitrogen protection and heated to 240℃ for esterification reaction for 2 h to obtain polyester oligomer melt. Then, 2.5 parts of γ-aminopropyltriethoxysilane were added to the oligomer melt and the reaction was continued at 450 r / min at 260℃ for 1 h to allow γ-aminopropyltriethoxysilane to undergo hydrolysis and condensation reaction and participate in polyester chain end reaction. Subsequently, the reaction pressure was gradually reduced to 80 Pa at 265℃ and polycondensation reaction was carried out for 2 h to obtain a single organosilicon modified polyester matrix resin. S2, Preparation of flame-retardant polyester melt 95 parts of the single organosilicon modified polyester matrix resin obtained in step S1 were added to a melt mixing device and stirred and melted at 200 r / min at 255℃ for 20 min; then 8 parts of CEPPA, 1.5 parts of ellagic acid, 0.2 parts of catalyst, 0.5 parts of antioxidant and 0.4 parts of stabilizer were added and stirred and mixed at 350 r / min at 265℃ for 40 min to obtain flame-retardant modified polyester melt; S3, Polyester Chip Preparation The flame-retardant modified polyester melt obtained in step S2 was melt extruded at 265°C with an extruder screw speed of 120 r / min. After water cooling, it was pelletized to obtain CEPPA flame-retardant polyester chip composite material.

[0031] Comparative Example 3: The purpose of this comparative example is to verify the effect of removing ellagic acid on the balance between the flame-retardant synergistic effect and the overall performance of flame-retardant polyester chip composites while keeping the structure of the synergistically modified polyester matrix resin unchanged.

[0032] S1, Preparation of Synergistically Modified Polyester Matrix Resin 95 parts of terephthalic acid and 55 parts of ethylene glycol were added to a reactor and stirred at 300 r / min under nitrogen protection while the temperature was raised to 240℃ for esterification for 2 h to obtain a polyester oligomer melt. Subsequently, 2 parts of catechol, 2 parts of phenylboronic acid, and 2.5 parts of γ-aminopropyltriethoxysilane were added to the oligomer melt, and the reaction was continued at 260℃ and 450 r / min for 1 h to allow catechol and phenylboronic acid to form a dynamic borate ester structure, while γ-aminopropyltriethoxysilane underwent a hydrolysis-condensation reaction. Then, the reaction pressure was gradually reduced to 80 Pa at 265℃ and a polycondensation reaction was carried out for 2 h to obtain a synergistically modified polyester matrix resin. S2, Preparation of flame-retardant polyester melt 95 parts of the synergistically modified polyester matrix resin obtained in step S1 were added to a melt mixing device and stirred and melted at 200 r / min at 255℃ for 20 min; then 8 parts of CEPPA, 0.2 parts of catalyst, 0.5 parts of antioxidant and 0.4 parts of stabilizer were added and stirred and mixed at 350 r / min at 265℃ for 40 min to obtain flame-retardant modified polyester melt. S3, Polyester Chip Preparation The flame-retardant modified polyester melt obtained in step S2 was melt extruded at 265°C with an extruder screw speed of 120 r / min. After water cooling, it was pelletized to obtain CEPPA flame-retardant polyester chip composite material.

[0033] Performance testing: 1. Limiting Oxygen Index Test Method The CEPPA flame-retardant polyester chips obtained in the examples and comparative examples were prepared into standard samples with a thickness of 3 mm using a twin-screw extruder, and then cut into test strips with dimensions of 100 mm × 10 mm × 3 mm. The tests were conducted according to GB / T 2406.2—2009 "Determination of Burning Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test". The samples were vertically fixed in the combustion test apparatus, and ignited under controlled oxygen and nitrogen mixing ratios. The minimum oxygen concentration required to maintain continuous combustion of the sample, i.e., the limiting oxygen index value, was determined by adjusting the oxygen concentration. Each group of samples was tested 5 times, and the average value was taken as the final result.

[0034] 2. Vertical combustion performance test method The CEPPA flame-retardant polyester chips obtained in the examples and comparative examples were melt-extruded to prepare standard samples with a thickness of 3 mm, and then processed into test strips of 125 mm × 13 mm × 3 mm. The test was conducted according to the UL-94 vertical burning test standard. The sample was vertically fixed in a combustion device, and the bottom of the sample was ignited with a specified flame for 10 s. The self-extinguishing time and dripping after removal of the flame were recorded. The sample was then ignited again for 10 s, and the second burning time was recorded. The flame retardant rating was evaluated based on the sample's burning behavior.

[0035] 3. Thermogravimetric analysis test method Approximately 5–10 mg of CEPPA flame-retardant polyester chip samples obtained in the examples and comparative examples were placed in the sample crucible of a thermogravimetric analyzer and thermogravimetric analysis was performed under a nitrogen protective atmosphere. The heating range was 30–800 °C, and the heating rate was 10 °C / min. By recording the mass change curves of the samples during the heating process, the initial decomposition temperature, the maximum weight loss rate temperature, and the char residue at 800 °C were analyzed to evaluate the thermal stability and carbonization ability of the materials.

[0036] 4. Tensile property test methods The CEPPA flame-retardant polyester chips obtained in the examples and comparative examples were prepared into standard dumbbell-shaped specimens using an injection molding machine. The specimen dimensions were prepared according to GB / T 1040.2—2006 "Determination of tensile properties of plastics—Part 2: Test conditions for molded and extruded plastics". The specimens were mounted on an electronic universal testing machine and tested at 23°C with a tensile speed set to 50 mm / min. The tensile strength and elongation at break of the material were measured. Each group of specimens was tested 5 times, and the average value was taken as the final test result.

[0037] Table 1. Performance test results of flame-retardant polyester chip composite materials in the examples and comparative examples.

[0038] As shown in Table 1, the CEPPA flame-retardant polyester chip composite materials of Examples 1-3 and Comparative Examples 1-3 exhibit significant differences in limiting oxygen index, UL-94 flame retardancy rating, char residue, and tensile strength. Overall, the flame-retardant performance, thermal stability, and mechanical properties of the materials obtained in the embodiments of this invention are significantly better than those of the comparative examples. Example 2 shows the best overall performance, indicating that the synergistic modification structure constructed in this invention can effectively enhance the synergistic effect of the CEPPA flame-retardant system.

[0039] Based on the limiting oxygen index and UL-94 flame retardancy rating results... Figure 2 The limiting oxygen indices (LOIs) of Examples 1-3 reached 31.5%, 34.7%, and 32.8%, respectively, significantly higher than those of Comparative Examples 1-3 (28.6%, 29.1%, and 27.9%). Furthermore, Example 2 achieved a V-0 flame retardant rating, while the comparative examples only reached a V-2 rating. This indicates that constructing a modified network with a synergistic effect between dynamic borate ester and organosilicon structures within the polyester matrix, and introducing ellagic acid as a small organic molecule regulator, can significantly improve the flame retardant synergistic efficiency of CEPPA in the polyester system, thereby effectively suppressing the heat release behavior during material combustion.

[0040] Thermogravimetric analysis results show that the char residue rates of Examples 1-3 at 800℃ reached 16.8%, 20.6%, and 18.9%, respectively, which are significantly higher than the 12.8%-14.1% of the comparative materials. Among them, Example 2 had the highest char residue rate, indicating that the synergistic modified structure constructed in this invention can promote the formation of a stable char layer under high temperature conditions, thereby effectively improving the thermal stability of the material and enhancing the integrity of the flame-retardant protective layer.

[0041] From the mechanical property results, the tensile strengths of Examples 1-3 were 61.3 MPa, 67.5 MPa, and 64.2 MPa, respectively, all higher than the 55.4-57.2 MPa of the comparative materials. This indicates that with the introduction of CEPPA, the present invention can effectively enhance the interaction forces between polyester molecular chains through synergistic modification of the polyester matrix structure, thereby reducing the adverse effects of CEPPA on the polyester molecular weight and mechanical properties, enabling the material to maintain good mechanical properties while achieving excellent flame retardant properties.

[0042] In summary, this invention constructs a polyester matrix network with synergistic effects of dynamic borate ester structure and organosilicon structure, and introduces ellagic acid for molecular structure regulation, thereby significantly enhancing the flame retardant synergistic effect of CEPPA in the polyester system, thus achieving a synergistic improvement in flame retardant performance, thermal stability and mechanical properties. Among them, Example 2 shows the best performance in all performance indicators, indicating that the material's comprehensive performance reaches the optimal state under the recommended median range.

Claims

1. A CEPPA flame-retardant polyester chip composite material, characterized in that, The flame-retardant polyester chip composite material comprises the following raw materials in parts by weight: 80-110 parts of synergistically modified polyester matrix resin; 3-15 parts of CEPPA; 0.1-3 parts of organic small molecule functional regulator; 0.01-0.5 parts of catalyst; 0.1-1.0 parts of antioxidant; and 0.05-0.8 parts of stabilizer. The synergistically modified polyester matrix resin is a polyester resin obtained by synergistic modification during the polycondensation reaction of terephthalic acid and ethylene glycol, through the formation of dynamic borate ester bond structure between catechol and phenylboronic acid, and the hydrolysis and condensation reaction with γ-aminopropyltriethoxysilane. The organic small molecule functional regulator is ellagic acid.

2. The CEPPA-based flame-retardant polyester chip composite material according to claim 1, characterized in that, The synergistically modified polyester matrix resin comprises the following raw materials in parts by weight: 80-110 parts terephthalic acid; 40-70 parts ethylene glycol; 0.5-4 parts catechol; 0.5-4 parts phenylboronic acid; and 0.5-5 parts γ-aminopropyltriethoxysilane.

3. A CEPPA-based flame-retardant polyester chip composite material according to claim 1 or 2, characterized in that, The preparation method of the synergistically modified polyester matrix resin includes the following steps: (1) Terephthalic acid and ethylene glycol are mixed and subjected to esterification reaction to obtain polyester oligomer melt; (2) Add catechol, phenylboronic acid and γ-aminopropyltriethoxysilane to the polyester oligomer melt to react and obtain a synergistic modification reaction system; (3) The synergistic modification reaction system is subjected to polycondensation reaction. After the reaction is completed, the melt is extruded and pelletized to obtain the synergistic modified polyester matrix resin.

4. The CEPPA-based flame-retardant polyester chip composite material according to claim 3, characterized in that, The reaction conditions for step (1) are as follows: esterification reaction is carried out at 220-260°C under nitrogen protection, with a stirring speed of 200-400 r / min and a reaction time of 1-3 h.

5. The CEPPA-based flame-retardant polyester chip composite material according to claim 3, characterized in that, The reaction conditions for step (2) are as follows: the reaction is carried out at 240-280°C, the stirring speed is 300-600 r / min, and the reaction time is 0.5-2 h.

6. The CEPPA-based flame-retardant polyester chip composite material according to claim 3, characterized in that, The reaction conditions for step (3) are as follows: polycondensation reaction is carried out under gradually reduced pressure conditions, with a reaction pressure of 10-200 Pa, a reaction temperature of 250-280℃, and a reaction time of 1-3 h.

7. The CEPPA-based flame-retardant polyester chip composite material according to claim 1, characterized in that, The catalyst is a mixture of antimony trioxide and tetrabutyltitanium in a mass ratio of 1 to 5:1; the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1 to 3:1; and the stabilizer is a mixture of calcium stearate and triphenyl phosphite in a mass ratio of 1 to 4:

1.

8. A method for preparing flame-retardant polyester chip composite material using CEPPA, characterized in that, The preparation method includes the following steps: S1, the synergistically modified polyester matrix resin is added to a melt mixing device and heated and melted to obtain a polyester melt; S2, CEPPA, organic small molecule functional regulators, catalysts, antioxidants and stabilizers are added to the polyester melt and mixed in the molten state to obtain flame-retardant modified polyester melt; S3 involves extruding, cooling, and pelletizing the flame-retardant modified polyester melt to obtain CEPPA flame-retardant polyester chip composite material.

9. The method for preparing flame-retardant polyester chip composite material from CEPPA according to claim 8, characterized in that, The reaction conditions for step S1 are: melting treatment at 240–270°C, stirring speed of 100–300 r / min, and melting time of 10–30 min; the reaction conditions for step S2 are: mixing reaction at 250–280°C, stirring speed of 200–500 r / min, and reaction time of 20–60 min.

10. A method for preparing flame-retardant polyester chip composite material from CEPPA according to claim 8, characterized in that, The reaction conditions for step S3 are melt extrusion at 250-280°C, extruder screw speed of 50-200 r / min, and pelletizing after water cooling to obtain flame-retardant polyester chip composite material.

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