A high-strength PET preform and its preparation method

Abstract

This invention discloses a high-strength PET preform and its preparation method, relating to the field of PET preform technology. The high-strength PET preform comprises, by mass parts: 80-100 parts PET granules, 10-20 parts toughening PET-based copolyester, 10-20 parts flame-retardant PET-based copolyester, 0.5-1 parts chain extender, and 4-8 parts compatibilizer. The toughening PET-based copolyester is prepared by copolymerizing an elastomer obtained from bisphenol A diglycidyl ether and sebacic acid with polyethylene terephthalate; the flame-retardant PET-based copolyester is prepared by copolymerizing benzimidazole monomer with dimethyl terephthalate; the chain extender is any one of triglycidyl isocyanurate or 2,2'-(1,3-phenylene)-dioxazoline; and the compatibilizer is prepared by reacting p-phenylenediamine, 4-hydroxybenzaldehyde, and DOPO.

Description

Technical Field

[0001] This invention relates to the field of PET preform technology, specifically a high-strength PET preform and its preparation method. Background Technology

[0002] Polyethylene terephthalate (PET) is widely used in bottle preforms, packaging materials, and other fields due to its excellent mechanical properties, chemical resistance, and transparency. However, with the diversification of applications, especially in areas requiring high-temperature resistance or flame retardancy, the performance of ordinary PET materials is insufficient. Therefore, introducing flame retardants into PET to improve its flame retardant properties has become a research hotspot.

[0003] In existing technologies, organic or inorganic flame retardants are typically added directly to the PET matrix. However, these flame retardants have poor compatibility with PET, which can lead to a significant decrease in the material's mechanical properties, particularly in tensile and impact strength. Furthermore, the addition of flame retardants may disrupt the molecular chain structure or crystal morphology of PET, further reducing the material's overall performance and limiting its applicability in high-strength applications.

[0004] On the other hand, PET material inherently has poor toughness and low elongation at break. Especially under high-strength and complex molding conditions, its brittleness is more pronounced, making the products prone to cracking or breakage. Although existing technologies attempt to improve the toughness of PET through blending toughening agents or modifiers, there is often a performance trade-off between flame retardant modification and toughness improvement, making it difficult to simultaneously achieve high strength, high toughness, and flame retardant properties.

[0005] Therefore, how to significantly improve the flame retardancy and elongation at break of PET preforms while ensuring their high strength, and how to develop a PET preform material and its preparation method with a comprehensive balance of performance, is a key technical problem that urgently needs to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide a high-strength PET preform and its preparation method to solve the problems raised in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A high-strength PET preform, comprising the following components: PET granules, toughened PET-based copolyester, flame-retardant PET-based copolyester, chain extender, and compatibilizer;

[0009] Furthermore, the toughened PET-based copolyester is prepared by copolymerizing an elastomer obtained from bisphenol A diglycidyl ether and sebacic acid with polyethylene terephthalate.

[0010] Furthermore, the flame-retardant PET-based copolyester is prepared by copolymerization of benzimidazole monomer and dimethyl terephthalate;

[0011] Furthermore, the chain extender is either triglycidyl isocyanurate or 2,2'-(1,3-phenylene)-dioxazoline;

[0012] Furthermore, the compatibilizer is prepared by reacting p-phenylenediamine, 4-hydroxybenzaldehyde, and DOPO.

[0013] Furthermore, the proportions of each component in the high-strength PET preform, by mass parts, include: 80-100 parts PET granules, 10-20 parts toughened PET-based copolyester, 20-30 parts flame-retardant PET-based copolyester, 0.5-1 parts chain extender, and 4-8 parts compatibilizer.

[0014] Furthermore, the method for preparing the toughened PET-based copolyester includes the following steps:

[0015] Sebacic acid was added to a reaction vessel and heated to 130-132℃ to dissolve. The mixture was then cooled to 124-125℃. The dissolved sebacic acid was added to bisphenol A diglycidyl ether and kept warm while stirring until homogeneous. 1,5,7-triazabicyclo[4.4.0]decene-5-ene was added and stirred until homogeneous. The mixture was kept warm for 3-3.5 hours and then heated to 160-162℃ for 6-6.5 hours to obtain the elastomer.

[0016] Elastomer is added to ethylene glycol and heated to 180-182℃ to dissolve, obtaining a mixed solution. Terephthalic acid, ethylene glycol, and tetrabutyl titanate are added to a reaction vessel and heated to 260-265℃ under a nitrogen atmosphere until the collected water reaches 90% of the theoretical amount required to produce the prepolymer. The mixed solution is then added and heated to 280-285℃ for vacuum polycondensation. The product is poured into ice water, filtered, and the precipitate is collected and vacuum dried to obtain toughened PET-based copolyester.

[0017] Furthermore, in the preparation process of the elastomer, the molar ratio of sebacic acid to bisphenol A diglycidyl ether is 1:1, and the amount of 1,5,7-triazabicyclo[4.4.0]decene-5-ene added is 5-10 wt% of the total mass of sebacic acid and bisphenol A diglycidyl ether.

[0018] Furthermore, the proportions of each component in the preparation process of the toughened PET-based copolyester, by mass parts, include: 400-450 parts of terephthalic acid, 190-200 parts of ethylene glycol, 1.25-5 parts of elastomer, and 0.25-0.3 parts of tetrabutyl titanate.

[0019] Furthermore, the preparation method of the flame-retardant PET-based copolyester includes the following steps:

[0020] Sodium metabisulfite was added to a mixture of methyl 4-formylbenzoate, methyl 3,4-diaminobenzoate, and N,N-dimethylformamide, stirred until homogeneous, and heated to 130-135℃ for 6-7 hours. The product was then poured into ice water, kept warm and stirred for 2-3 hours, filtered, and the precipitate was collected. The precipitate was washed with deionized water and ethyl acetate, and dried under vacuum to obtain benzimidazole monomer.

[0021] Dimethyl terephthalate, ethylene glycol, and benzimidazole monomer were added to a reaction vessel and heated to 180-182°C under a nitrogen atmosphere. Tetrabutyl titanate was then added, and a temperature-programmed reaction was carried out to obtain a flame-retardant PET-based copolyester.

[0022] Furthermore, in the preparation process of the benzimidazole, the molar ratio of sodium metabisulfite: methyl 4-formylbenzoate: methyl 3,4-diaminobenzoate is 1:1:1.

[0023] Furthermore, in the preparation process of the PET-based copolyester, the molar ratio of dimethyl terephthalate: ethylene glycol: benzimidazole monomer is (0.4-0.5):(1-1.25):(0.04-0.05); the temperature program includes: reacting at 210-215℃ for 2.5-3 hours, reacting at 240-245℃ for 1 hour, reducing the atmospheric pressure of the reaction system to 30 Pa, and heating to 260-265℃ for 2.5 hours.

[0024] Furthermore, the method for preparing the compatibilizer includes the following steps:

[0025] p-phenylenediamine and 4-hydroxybenzaldehyde were added to anhydrous ethanol and heated to 40-42℃ for 4-5 hours. Then, anhydrous ethanol solution of DOPO was added and heated to 65-66℃ for 8-9 hours. The mixture was filtered, the precipitate was collected, washed with anhydrous ethanol, and dried under vacuum to obtain the compatibilizer.

[0026] Furthermore, in the preparation process of the compatibilizer, the molar ratio of p-phenylenediamine: 4-hydroxybenzaldehyde: DOPO is 0.5:1:1.

[0027] A method for preparing a high-strength PET preform includes the following steps: adding PET granules, toughened PET-based copolyester, flame-retardant PET-based copolyester, chain extender, and compatibilizer sequentially into a mixer according to a predetermined ratio, then melting and extruding, and injection molding to obtain a high-strength PET preform.

[0028] Furthermore, the melt extrusion temperature is divided into 10 ranges: 200℃, 240℃, 250℃, 260℃, 265℃, 265℃, 265℃, 265℃, 265℃, and 265℃.

[0029] Furthermore, the injection pressure is 7Psi, the injection temperature is 270-300℃, the injection time is 2-10s, the holding time is 2-5s, and the cooling time is 3-4s.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] 1. This invention employs a two-step melt polymerization strategy to copolymerize an elastomer prepared from bisphenol A diglycidyl ether and sebacic acid with polyethylene terephthalate (PET) to obtain a toughened PET-based copolyester. Due to the disruption of the molecular chain regularity and partial cross-linking, the introduction of the elastomer polymer slightly reduces crystallinity but does not alter the PET crystal structure. After introducing the elastomer polymer, the copolymer's toughness is significantly improved, and the mechanical properties of the polymer further increase with increasing elastomer polymer content. These results are attributed to the long-chain segments and partially cross-linked structure induced by the elastomer polymer, thereby achieving the toughening effect.

[0032] 2. This invention prepares a flame-retardant PET-based copolymer by introducing benzimidazole groups into the molecular chain of a thermoplastic polymer. A physical cross-linking network is constructed through hydrogen bonding and π-π stacking interactions, maintaining this network structure even in the molten state. The formation of this physical cross-linking network effectively restricts molecular chain movement, leading to a significant increase in melt strength. This delays melt dripping, allowing sufficient time for polymer charring, which helps improve the droplet behavior of the thermoplastic polymer, endows the copolymer with excellent flame-retardant properties, expands the application fields of PET preforms, and further improves the cross-linking network structure of the copolymer matrix to a certain extent, thereby increasing the strength of the PET preform.

[0033] 3. This invention employs a one-step method to synthesize a P / N-based compatibilizer. Based on the introduction of toughened PET-based copolyester and flame-retardant PET-based copolyester, the proportion of chain extender and self-made compatibilizer is adjusted. By utilizing the strong interfacial interaction between the compatibilizer and the toughened PET-based copolyester and flame-retardant PET-based copolyester in the PET matrix, the dispersion of the toughened PET-based copolyester and flame-retardant PET-based copolyester in the PET matrix is ​​enhanced. This achieves the goal of improving the mechanical properties and flame-retardant properties of the copolymer while maintaining the same proportion of toughened PET-based copolyester and flame-retardant PET-based copolyester, and further improving the flame-retardant efficiency of the copolymer. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0035] In the following examples, the PET granules were of the following specifications: viscosity of 0.8 dL / g, type BG80, purchased from Sinopec Shanghai Petrochemical Co., Ltd., and the remaining raw materials were commercially available.

[0036] A method for preparing toughened PET-based copolyester includes the following steps:

[0037] 0.1 mol sebacic acid was added to a reaction vessel and heated to 130°C to dissolve. The mixture was then cooled to 124°C. The dissolved sebacic acid was added to 0.1 mol bisphenol A diglycidyl ether and kept warm while stirring until homogeneous. 5 wt% 1,5,7-triazabicyclo[4.4.0]decene-5-ene was added and stirred until homogeneous. The mixture was kept warm for 3 hours and then heated to 160°C for 6 hours to obtain the elastomer.

[0038] 1.25 parts of elastomer were added to ethylene glycol and heated to 180°C to dissolve, resulting in a mixed solution. 400 parts of phthalic acid, 190 parts of ethylene glycol, and 0.25 parts of tetrabutyl titanate were added to a reaction vessel and heated to 260°C under a nitrogen atmosphere until the collected water reached 90% of the theoretical amount required for producing the prepolymer. The mixed solution was then added, and the mixture was heated to 280°C for vacuum polycondensation. The product was poured into ice water, filtered, and the precipitate was collected and vacuum dried to obtain a toughened PET-based copolyester.

[0039] A method for preparing flame-retardant PET-based copolyester includes the following steps:

[0040] 0.2 mol sodium metabisulfite was added to 250 mL of a mixture containing 0.2 mol methyl 4-formylbenzoate and 0.2 mol methyl 3,4-diaminobenzoate, stirred until homogeneous, heated to 130 °C and reacted for 6 h. The product was poured into ice water, kept warm and stirred for 2 h, filtered, the precipitate was collected, washed with deionized water and ethyl acetate, and dried under vacuum to obtain benzimidazole monomer.

[0041] 0.4 mol of dimethyl terephthalate, 1 mol of ethylene glycol, and 0.04 mol of benzimidazole monomer were added to a reaction vessel and heated to 180°C under a nitrogen atmosphere. Then, 0.027 g of tetrabutyl titanate was added, and the reaction was carried out at 210°C for 2.5 h and at 240°C for 1 h. The atmospheric pressure of the reaction system was reduced to 30 Pa, and the system was further heated to 260°C for 2.5 h to obtain a flame-retardant PET-based copolyester.

[0042] The method for preparing a compatibilizer includes the following steps:

[0043] 0.5 mol p-phenylenediamine and 1 mol 4-hydroxybenzaldehyde were added to anhydrous ethanol and heated to 40 °C for 4 h. Then, 1 mol DOPO in anhydrous ethanol solution was added and heated to 65 °C for 8 h. The mixture was filtered, the precipitate was collected, washed with anhydrous ethanol, and dried under vacuum to obtain the compatibilizer.

[0044] Example 1: A method for preparing a high-strength PET preform, comprising the following steps: 100 parts of PET granules, 10 parts of toughened PET-based copolyester, 20 parts of flame-retardant PET-based copolyester, 0.8 parts of triglycidyl isocyanurate, and 4 parts of compatibilizer are sequentially added to a mixer, melt-extruded, and injection molded to obtain a high-strength PET preform.

[0045] The melt extrusion temperature is divided into 10 stages: 200℃, 240℃, 250℃, 260℃, 265℃, 265℃, 265℃, 265℃, 265℃, and 265℃. The injection pressure is 7Psi, the injection temperature is 285℃, the injection time is 5s, the holding time is 3s, and the cooling time is 3s.

[0046] Example 2: A method for preparing a high-strength PET preform, comprising the following steps: 100 parts of PET granules, 10 parts of toughened PET-based copolyester, 30 parts of flame-retardant PET-based copolyester, 0.8 parts of triglycidyl isocyanurate, and 4 parts of compatibilizer are sequentially added to a mixer, melt-extruded, and injection molded to obtain a high-strength PET preform.

[0047] Example 3: A method for preparing a high-strength PET preform, comprising the following steps: 100 parts of PET granules, 20 parts of toughened PET-based copolyester, 20 parts of flame-retardant PET-based copolyester, 0.8 parts of triglycidyl isocyanurate, and 4 parts of compatibilizer are sequentially added to a mixer, melt-extruded, and injection molded to obtain a high-strength PET preform.

[0048] Example 4: A method for preparing a high-strength PET preform, comprising the following steps: A method for preparing a toughened PET-based copolyester, comprising the following steps:

[0049] 0.1 mol sebacic acid was added to a reaction vessel and heated to 130°C to dissolve. The mixture was then cooled to 124°C. The dissolved sebacic acid was added to 0.1 mol bisphenol A diglycidyl ether and kept warm while stirring until homogeneous. 5 wt% 1,5,7-triazabicyclo[4.4.0]decene-5-ene was added and stirred until homogeneous. The mixture was kept warm for 3 hours and then heated to 160°C for 6 hours to obtain the elastomer.

[0050] 1.25 parts of elastomer were added to ethylene glycol and heated to 180°C to dissolve, resulting in a mixed solution. 400 parts of phthalic acid, 190 parts of ethylene glycol, and 0.25 parts of tetrabutyl titanate were added to a reaction vessel and heated to 260°C under a nitrogen atmosphere until the collected water reached 90% of the theoretical amount required for producing the prepolymer. The mixed solution was then added, and the mixture was heated to 280°C for vacuum polycondensation. The product was poured into ice water, filtered, and the precipitate was collected and vacuum dried to obtain a toughened PET-based copolyester.

[0051] The remaining steps are the same as in Example 1.

[0052] Example 5: A method for preparing a high-strength PET preform, comprising the following steps: 100 parts of PET granules, 20 parts of toughened PET-based copolyester, 20 parts of flame-retardant PET-based copolyester, 0.8 parts of triglycidyl isocyanurate, and 6 parts of compatibilizer are sequentially added to a mixer, melt-extruded, and injection molded to obtain a high-strength PET preform.

[0053] Example 6: A method for preparing a high-strength PET preform, comprising the following steps: 100 parts of PET granules, 20 parts of toughened PET-based copolyester, 20 parts of flame-retardant PET-based copolyester, 0.8 parts of triglycidyl isocyanurate, and 8 parts of compatibilizer are sequentially added to a mixer, melt-extruded, and injection molded to obtain a high-strength PET preform.

[0054] Comparative Example 1: A method for preparing a high-strength PET preform, comprising the following steps: adding 100 parts of PET granules, 10 parts of toughened PET-based copolyester, 20 parts of DOPO, 0.8 parts of triglycidyl isocyanurate, and 4 parts of compatibilizer sequentially into a mixer, melting and extruding, and injection molding to obtain a high-strength PET preform.

[0055] Comparative Example 2: A method for preparing a high-strength PET preform, comprising the following steps: adding 110 parts of PET granules, 20 parts of flame-retardant PET-based copolyester, 0.8 parts of triglycidyl isocyanurate, and 4 parts of compatibilizer sequentially into a mixer, melting and extruding, and injection molding to obtain a high-strength PET preform.

[0056] Comparative Example 3: A method for preparing a high-strength PET preform, comprising the following steps: adding 120 parts of PET granules, 10 parts of toughened PET-based copolyester, 0.8 parts of triglycidyl isocyanurate, and 4 parts of compatibilizer sequentially into a mixer, melting and extruding, and injection molding to obtain a high-strength PET preform.

[0057] Comparative Example 4: A method for preparing a high-strength PET preform, comprising the following steps: adding 100 parts of PET granules, 30 parts of toughened PET-based copolyester, 20 parts of flame-retardant PET-based copolyester, 0.8 parts of triglycidyl isocyanurate, and 4 parts of compatibilizer sequentially into a mixer, melting and extruding, and injection molding to obtain a high-strength PET preform.

[0058] Comparative Example 5: A method for preparing a high-strength PET preform, comprising the following steps: adding 100 parts of PET granules, 10 parts of toughened PET-based copolyester, 40 parts of flame-retardant PET-based copolyester, 0.8 parts of triglycidyl isocyanurate, and 4 parts of compatibilizer sequentially into a mixer, melting and extruding, and injection molding to obtain a high-strength PET preform.

[0059] Comparative Example 6: A method for preparing a high-strength PET preform, comprising the following steps: adding 100 parts of PET granules, 10 parts of toughened PET-based copolyester, 20 parts of flame-retardant PET-based copolyester, and 0.8 parts of triglycidyl isocyanurate sequentially into a mixer, melting and extruding, and injection molding to obtain a high-strength PET preform.

[0060] Comparative Example 7: A method for preparing a high-strength PET preform, comprising the following steps: adding 100 parts of PET granules, 10 parts of toughened PET-based copolyester, 30 parts of flame-retardant PET-based copolyester, and 0.8 parts of triglycidyl isocyanurate sequentially into a mixer, melting and extruding, and injection molding to obtain a high-strength PET preform.

[0061] Comparative Example 8: A method for preparing a high-strength PET preform, comprising the following steps: adding 100 parts of PET granules, 20 parts of toughened PET-based copolyester, 20 parts of flame-retardant PET-based copolyester, and 0.8 parts of triglycidyl isocyanurate sequentially into a mixer, melting and extruding, and injection molding to obtain a high-strength PET preform.

[0062] Experiment: Determination of mechanical properties: Tests were conducted according to GB / T 1040.3-2006. The polyester granules prepared by melt extrusion in the above examples and comparative examples were pressed into sheets with a thickness of 1 mm and a length and width of 150 mm × 10 mm. The prepared samples were tested using an electronic universal tensile testing machine at a tensile speed of 100 mm / min. Each sheet sample was tested three times, and the final result was expressed as the average value.

[0063] Flame retardant performance determination: The test was conducted according to ASTM D2863-97. The polyester granules prepared by melt extrusion in the above examples and comparative examples were pressed into sheets with a thickness of 3.2 mm and a length and width of 120 mm × 6.5 mm. The limiting oxygen index (LOI) was determined. Each sheet sample was tested three times. The final result is expressed as the average value.

[0064] The polyester granules obtained by melt extrusion in the above examples and comparative examples were pressed into sheets with a thickness of 3.2 mm and a length and width of 130 mm × 13 mm. The UL-94 was measured using a CZF-2 instrument. The experiment was repeated three times for each sheet sample, and the final result was expressed as the average value.

[0065] The specific experimental results are shown in Table 1 below.

[0066] Table 1. Performance Test Data of High-Strength PET Preform Raw Material Polyester Particles

[0067]

[0068] Conclusion: The PET preforms prepared by this invention have excellent mechanical properties and flame retardant properties.

[0069] In Comparative Example 1, the flame-retardant PET-based copolyester was directly replaced with commercially available DOPO, resulting in a reduction in mechanical properties.

[0070] In Comparative Example 2, the absence of toughened PET-based copolyester resulted in reduced mechanical properties.

[0071] In Comparative Example 3, no flame-retardant PET-based copolyester was added, resulting in a reduction in flame-retardant performance.

[0072] The addition of excessive toughened PET-based copolyester in Comparative Example 4 resulted in a decrease in mechanical properties.

[0073] The addition of excessive flame-retardant PET-based copolyester in Comparative Example 5 resulted in a decrease in mechanical properties.

[0074] No compatibilizer was added in Comparative Example 6, which resulted in a decrease in mechanical and flame retardant properties.

[0075] In Comparative Example 7, the amount of flame-retardant PET-based copolyester added was increased without the addition of compatibilizer, but the improvement effect was worse than that in Example 2.

[0076] In Comparative Example 8, the amount of toughened PET-based copolyester added was increased without the addition of compatibilizer, but the improvement effect was worse than that in Example 3.

[0077] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A high-strength PET preform, characterized in that: The high-strength PET preform comprises the following components, by weight: 80-100 parts PET granules, 10-20 parts toughened PET-based copolyester, 20-30 parts flame-retardant PET-based copolyester, 0.5-1 part chain extender, and 4-8 parts compatibilizer. The chain extender is either triglycidyl isocyanurate or 2,2'-(1,3-phenylene)-dioxazoline; The method for preparing the toughened PET-based copolyester includes the following steps: Sebacic acid was added to a reaction vessel and heated to 130-132℃ to dissolve. The mixture was then cooled to 124-125℃. The dissolved sebacic acid was added to bisphenol A diglycidyl ether and kept warm while stirring until homogeneous. 1,5,7-triazabicyclo[4.4.0]decene-5-ene was added and stirred until homogeneous. The mixture was kept warm for 3-3.5 hours and then heated to 160-162℃ for 6-6.5 hours to obtain the elastomer. Elastomer is added to ethylene glycol and heated to 180-182℃ to dissolve, obtaining a mixed solution. Terephthalic acid, ethylene glycol, and tetrabutyl titanate are added to a reaction vessel and heated to 260-265℃ under a nitrogen atmosphere until the collected water reaches 90% of the theoretical amount required to produce the prepolymer. The mixed solution is then added and heated to 280-285℃ for vacuum polycondensation. The product is poured into ice water, filtered, the precipitate is collected, and vacuum dried to obtain toughened PET-based copolyester. The preparation method of the flame-retardant PET-based copolyester includes the following steps: Sodium metabisulfite was added to a mixture of methyl 4-formylbenzoate, methyl 3,4-diaminobenzoate, and N,N-dimethylformamide, stirred until homogeneous, and heated to 130-135℃ for 6-7 hours. The product was then poured into ice water, kept warm and stirred for 2-3 hours, filtered, and the precipitate was collected. The precipitate was washed with deionized water and ethyl acetate, and dried under vacuum to obtain benzimidazole monomer. Dimethyl terephthalate, ethylene glycol and benzimidazole monomer were added to a reaction vessel and heated to 180-182°C under a nitrogen atmosphere. Tetrabutyl titanate was then added, and a temperature-programmed reaction was carried out to obtain a flame-retardant PET-based copolyester. The method for preparing the compatibilizer includes the following steps: p-phenylenediamine and 4-hydroxybenzaldehyde were added to anhydrous ethanol and heated to 40-42℃ for 4-5 hours. Then, anhydrous ethanol solution of DOPO was added and heated to 65-66℃ for 8-9 hours. The mixture was filtered, the precipitate was collected, washed with anhydrous ethanol, and dried under vacuum to obtain the compatibilizer. In the preparation of the compatibilizer, the molar ratio of p-phenylenediamine: 4-hydroxybenzaldehyde: DOPO is 0.5:1:

1.

2. The high-strength PET preform according to claim 1, characterized in that: In the preparation of the elastomer, the molar ratio of sebacic acid to bisphenol A diglycidyl ether is 1:1, and the amount of 1,5,7-triazabicyclo[4.4.0]decene-5-ene added is 5-10 wt% of the total mass of sebacic acid and bisphenol A diglycidyl ether.

3. The high-strength PET preform according to claim 1, characterized in that: The proportions of each component in the preparation process of toughened PET-based copolyester, by mass parts, include: 400-450 parts of terephthalic acid, 190-200 parts of ethylene glycol, 1.25-5 parts of elastomer, and 0.25-0.3 parts of tetrabutyl titanate.

4. The high-strength PET preform according to claim 1, characterized in that: In the preparation of benzimidazole, the molar ratio of sodium metabisulfite: methyl 4-formylbenzoate: methyl 3,4-diaminobenzoate is 1:1:

1.

5. A high-strength PET preform according to claim 1, characterized in that: In the preparation of flame-retardant PET-based copolyester, the molar ratio of dimethyl terephthalate: ethylene glycol: benzimidazole monomer is (0.4-0.5):(1-1.25):(0.04-0.05); the temperature program includes: reacting at 210-215℃ for 2.5-3 hours, reacting at 240-245℃ for 1 hour, reducing the atmospheric pressure of the reaction system to 30 Pa, and heating to 260-265℃ for 2.5 hours.

6. A method for preparing a high-strength PET preform according to any one of claims 1-5, characterized in that: The process includes the following steps: adding PET granules, toughened PET-based copolyester, flame-retardant PET-based copolyester, chain extender, and compatibilizer to a mixer in a predetermined ratio, followed by melt extrusion and injection molding to obtain a high-strength PET preform.

Images