High-strength PET bottle preform and preparation method thereof

Abstract

The invention discloses a high-strength PET bottle preform and a preparation method thereof, and relates to the technical field of PET bottle preforms. The high-strength PET bottle blank is prepared from the following components in parts by mass: 80 to 100 parts of PET particles, 10 to 20 parts of toughened PET-based copolyester, 10 to 20 parts of flame-retardant PET-based copolyester, 0.5 to 1 part of chain extender and 4 to 8 parts of compatilizer. The toughened PET-based copolyester is prepared by copolymerizing an elastomer and polyethylene terephthalate, wherein the elastomer is prepared from bisphenol A diglycidyl ether and sebacic acid; the flame-retardant PET-based copolyester is prepared by copolymerization of a benzimidazole monomer and dimethyl terephthalate; the chain extender is any one of triglycidyl isocyanurate or 2, 2 '-(1, 3-phenylene)-dioxazoline, and the chain extender is any one of triglycidyl isocyanurate and 2, 2'-(1, 3-phenylene)-dioxazoline; the compatilizer is prepared from p-phenylenediamine, 4-hydroxybenzaldehyde and DOPO (9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) through

Description

Technical Field

[0001] The invention relates to the technical field of PET bottle preforms, in particular to a high-strength PET bottle preform and a preparation method thereof. Background Art

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

[0003] In the prior art, the method of directly adding organic or inorganic flame retardants to the PET matrix is ​​usually adopted. However, due to the poor compatibility of such flame retardants with PET, they are likely to cause a significant decrease in the mechanical properties of the material, especially in the degradation of tensile strength and impact strength. In addition, the addition of flame retardants may destroy the molecular chain structure or crystal morphology of PET, further reducing the comprehensive performance of the material and limiting its applicability in high-strength application scenarios.

[0004] On the other hand, PET materials have poor inherent toughness and low elongation at break. Especially under high-strength and complex molding processing conditions, their brittle characteristics are more obvious, causing the products to crack or break easily. Although the prior art attempts to improve the toughness of PET by blending toughening agents or modifiers, there is often a performance trade-off between flame retardant modification and toughness improvement, and it is difficult to take into account high strength, high toughness and flame retardant properties at the same time.

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

[0006] The object of the present invention is to provide a high-strength PET bottle embryo and a preparation method thereof, so as to solve the problems raised in the prior art.

[0007] To achieve the above object, the present invention provides the following technical solutions: A high-strength PET bottle blank, comprising the following components: PET particles, toughened PET-based copolyester, flame-retardant PET-based copolyester, chain extender, and compatibilizer; Furthermore, the toughened PET-based copolyester is prepared by copolymerizing an elastomer prepared from bisphenol A diglycidyl ether and sebacic acid with polyethylene terephthalate; Furthermore, the flame retardant PET-based copolyester is prepared by copolymerization of benzimidazole monomer and dimethyl terephthalate; Further, the chain extender is any one of triglycidyl isocyanurate or 2,2'-(1,3-phenylene)-bisoxazoline; Furthermore, the compatibilizer is prepared by reacting p-phenylenediamine, 4-hydroxybenzaldehyde and DOPO.

[0008] Furthermore, the proportions of the components in the high-strength PET bottle blank include, by mass, 80-100 parts of PET particles, 10-20 parts of toughened PET-based copolyester, 20-30 parts of flame-retardant PET-based copolyester, 0.5-1 parts of chain extender, and 4-8 parts of compatibilizer.

[0009] Furthermore, the preparation method of the toughened PET-based copolyester comprises the following steps: Add sebacic acid to a reaction container, heat to 130-132°C to dissolve, cool to 124-125°C, add the dissolved sebacic acid to bisphenol A diglycidyl ether, keep warm and stir evenly, add 1,5,7-triazabicyclo[4.4.0]decene-5-ene, stir evenly, keep warm and react for 3-3.5h, heat to 160-162°C and react for 6-6.5h to obtain an elastomer; The elastomer is added to ethylene glycol, heated to 180-182°C to dissolve, and a mixed solution is obtained; terephthalic acid, ethylene glycol, and tetrabutyl titanate are added to a reaction container, heated to 260-265°C under a nitrogen atmosphere, and reacted until the amount of water collected reaches 90% of the theoretical amount required for producing the prepolymer, the mixed solution is added, heated to 280-285°C, and vacuum polycondensed, the product is poured into ice water, filtered, the precipitate is collected, and vacuum dried to obtain a toughened PET-based copolyester.

[0010] Furthermore, during 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 5-10wt% of the total mass of sebacic acid and bisphenol A diglycidyl ether.

[0011] Furthermore, the proportions of the components in the preparation process of the toughened PET-based copolyester include, by mass, 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.

[0012] Furthermore, the method for preparing the flame retardant PET-based copolyester comprises the following steps: Add sodium metabisulfite to a mixture of methyl 4-formylbenzoate, methyl 3,4-diaminobenzoate and N,N-dimethylformamide, stir evenly, heat to 130-135°C for reaction for 6-7h, pour the product into ice water, keep warm and stir for 2-3h, filter, collect the precipitate, wash with deionized water and ethyl acetate, and vacuum dry to obtain a benzimidazole monomer; Dimethyl terephthalate, ethylene glycol and benzimidazole monomers are added into a reaction container, heated to 180-182° C. under a nitrogen atmosphere, and tetrabutyl titanate is added to perform a temperature-programmed reaction to obtain a flame-retardant PET-based copolyester.

[0013] Furthermore, in the preparation process of the benzimidazole, the molar ratio of sodium pyrosulfite: methyl 4-formylbenzoate: methyl 3,4-diaminobenzoate is 1:1:1.

[0014] 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°C for 2.5-3h, reacting at 240-245°C for 1h, reducing the atmospheric pressure of the reaction system to 30Pa, heating to 260-265°C and reacting for 2.5h.

[0015] Furthermore, the preparation method of the compatibilizer comprises the following steps: Add p-phenylenediamine and 4-hydroxybenzaldehyde to anhydrous ethanol, heat to 40-42°C for reaction for 4-5h, add anhydrous ethanol solution of DOPO, heat to 65-66°C for reaction for 8-9h, filter, collect the precipitate, wash with anhydrous ethanol, and vacuum dry to obtain a compatibilizer; Furthermore, during the preparation of the compatibilizer, the molar ratio of p-phenylenediamine:4-hydroxybenzaldehyde:DOPO is 0.5:1:1.

[0016] A method for preparing a high-strength PET bottle blank comprises the following steps: adding PET particles, toughened PET-based copolyester, flame-retardant PET-based copolyester, chain extender and compatibilizer into a mixer in sequence according to a predetermined ratio, melt-extruding and injection molding to obtain a high-strength PET bottle blank.

[0017] Further, the melt extrusion temperature is 10 stages, namely 200°C, 240°C, 250°C, 260°C, 265°C, 265°C, 265°C, 265°C, 265°C, 265°C; Furthermore, the injection pressure is 7 Psi, the injection temperature is 270-300° C., the injection time is 2-10 s, the holding time is 2-5 s, and the cooling time is 3-4 s.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses a two-step melt polymerization strategy to copolymerize an elastomer prepared from bisphenol A diglycidyl ether and sebacic acid with polyethylene terephthalate to prepare a toughened PET-based copolyester. Due to the destruction of the regularity and partial cross-linking of the molecular chain, the introduction of the elastomeric polymer slightly reduces the crystallinity, but does not cause changes in the PET crystal structure. After the introduction of the elastomeric polymer, the toughness of the copolymer is significantly improved, and as the content of the elastomeric polymer increases, the mechanical properties of the polymer are further increased. These results are attributed to the long chain segments and partially cross-linked structures induced by the elastomeric polymer, thereby achieving the technical effect of toughening.

[0019] 2. The present invention prepares a flame-retardant PET-based copolymer by introducing benzimidazole groups into the molecular chains of thermoplastic polymers, constructs a physical cross-linked network through hydrogen bonds and π-π stacking interactions, and can maintain this network structure even in a molten state. The formation of a physical cross-linked network can effectively limit the movement of the molecular chains, resulting in a significant increase in melt strength, thereby delaying melt dripping, allowing the polymer to have enough time to carbonize, helping to improve the droplet behavior of the thermoplastic polymer, giving the copolymer excellent flame retardant properties, expanding the application field of PET preforms, and further improving the cross-linked network structure of the copolymer matrix to a certain extent, thereby improving the strength of the PET preform.

[0020] 3. The present invention adopts a one-step method to synthesize a P / N-based compatibilizer. On the basis of introducing toughened PET-based copolyesters and flame-retardant PET-based copolyesters, by adjusting the ratio of a chain extender and a homemade compatibilizer, the compatibilizer is used to have a strong interface interaction with the toughened PET-based copolyester and the flame-retardant PET-based copolyester in the PET matrix, so that the dispersibility of the toughened PET-based copolyester and the flame-retardant PET-based copolyester in the PET matrix is ​​enhanced, so as to achieve the purpose of improving the mechanical properties and flame retardant properties of the copolymer on the basis of the same proportion of the toughened PET-based copolyester and the flame-retardant PET-based copolyester, and at the same time further improve the flame retardant efficiency of the copolymer. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the following examples, the PET particles have a viscosity of 0.8 dL / g, a model of BG80, purchased from Sinopec Shanghai Petrochemical Co., Ltd., and the remaining raw materials are commercially available.

[0023] The preparation method of toughened PET-based copolyester comprises the following steps: 0.1 mol of sebacic acid was added to a reaction container, heated to 130°C to dissolve, cooled to 124°C, the dissolved sebacic acid was added to 0.1 mol of bisphenol A diglycidyl ether, stirred evenly at the temperature, 5 wt% of 1,5,7-triazabicyclo[4.4.0]decene-5-ene was added, stirred evenly, the reaction was kept at the temperature for 3 hours, and heated to 160°C for 6 hours to obtain an elastomer; 1.25 parts of elastomer are added to ethylene glycol, heated to 180°C to dissolve, and a mixed solution is obtained; 400 parts of phthalic acid, 190 parts of ethylene glycol, and 0.25 parts of tetrabutyl titanate are added to a reaction container, heated to 260°C under a nitrogen atmosphere, and reacted until the amount of water collected reaches 90% of the theoretical amount required for producing the prepolymer, the mixed solution is added, heated to 280°C, and vacuum polycondensed, the product is poured into ice water, filtered, the precipitate is collected, and vacuum dried to obtain a toughened PET-based copolyester.

[0024] The preparation method of flame retardant PET-based copolyester comprises the following steps: Add 0.2 mol of sodium metabisulfite to a mixture of 0.2 mol of methyl 4-formylbenzoate and 0.2 mol of methyl 3,4-diaminobenzoate in 250 mL of N,N-dimethylformamide, stir evenly, heat to 130° C. to react for 6 h, pour the product into ice water, keep warm and stir for 2 h, filter, collect the precipitate, wash with deionized water and ethyl acetate, and vacuum dry to obtain a benzimidazole monomer; 0.4 mol of dimethyl terephthalate, 1 mol of ethylene glycol and 0.04 mol of benzimidazole monomer were added into a reaction container, heated to 180°C under a nitrogen atmosphere, 0.027 g of tetrabutyl titanate was added, and the mixture was reacted at 210°C for 2.5 h and 240°C for 1 h, then the atmospheric pressure of the reaction system was reduced to 30 Pa, and the mixture was further heated to 260°C for 2.5 h to obtain a flame-retardant PET-based copolyester.

[0025] The preparation method of the compatibilizer comprises the following steps: 0.5 mol of p-phenylenediamine and 1 mol of 4-hydroxybenzaldehyde were added to anhydrous ethanol, heated to 40°C for reaction for 4 hours, 1 mol of DOPO anhydrous ethanol solution was added, heated to 65°C for reaction for 8 hours, filtered, the precipitate was collected, washed with anhydrous ethanol, and vacuum dried to obtain a compatibilizer.

[0026] Embodiment 1: A method for preparing a high-strength PET preform, comprising the following steps: adding 100 parts of PET particles, 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 a compatibilizer into a blender in sequence, melt-extruding, and injection molding to obtain a high-strength PET preform; Among them, the melt extrusion temperature is 10 stages, namely 200℃, 240℃, 250℃, 260℃, 265℃, 265℃, 265℃, 265℃, 265℃, 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.

[0027] Example 2: A method for preparing a high-strength PET bottle blank, comprising the following steps: 100 parts of PET particles, 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 a compatibilizer are sequentially added into a blender, melt-extruded, and injection molded to obtain a high-strength PET bottle blank.

[0028] Example 3: A method for preparing a high-strength PET bottle blank, comprising the following steps: 100 parts of PET particles, 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 a compatibilizer are sequentially added into a blender, melt-extruded, and injection molded to obtain a high-strength PET bottle blank.

[0029] Example 4: A method for preparing a high-strength PET bottle embryo, comprising the following steps: A method for preparing a toughened PET-based copolyester, comprising the following steps: 0.1 mol of sebacic acid was added to a reaction container, heated to 130°C to dissolve, cooled to 124°C, the dissolved sebacic acid was added to 0.1 mol of bisphenol A diglycidyl ether, stirred evenly at the temperature, 5 wt% of 1,5,7-triazabicyclo[4.4.0]decene-5-ene was added, stirred evenly, the reaction was kept at the temperature for 3 hours, and heated to 160°C for 6 hours to obtain an elastomer; 1.25 parts of elastomer are added to ethylene glycol, heated to 180°C to dissolve, and a mixed solution is obtained; 400 parts of phthalic acid, 190 parts of ethylene glycol, and 0.25 parts of tetrabutyl titanate are added to a reaction container, heated to 260°C under a nitrogen atmosphere, and reacted until the amount of water collected reaches 90% of the theoretical amount required for producing the prepolymer, the mixed solution is added, heated to 280°C, and vacuum polycondensed, the product is poured into ice water, filtered, the precipitate is collected, and vacuum dried to obtain a toughened PET-based copolyester.

[0030] The remaining steps are the same as those in Example 1.

[0031] Example 5: A method for preparing a high-strength PET bottle blank, comprising the following steps: 100 parts of PET particles, 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 a compatibilizer are sequentially added into a blender, melt-extruded, and injection molded to obtain a high-strength PET bottle blank.

[0032] Example 6: A method for preparing a high-strength PET bottle blank, comprising the following steps: 100 parts of PET particles, 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 a compatibilizer are sequentially added into a blender, melt-extruded, and injection molded to obtain a high-strength PET bottle blank.

[0033] Comparative Example 1: A method for preparing a high-strength PET bottle blank, comprising the following steps: 100 parts of PET particles, 10 parts of toughened PET-based copolyester, 20 parts of DOPO, 0.8 parts of triglycidyl isocyanurate, and 4 parts of a compatibilizer are sequentially added into a blender, melt-extruded, and injection molded to obtain a high-strength PET bottle blank.

[0034] Comparative Example 2: A method for preparing a high-strength PET bottle blank, comprising the following steps: 110 parts of PET particles, 20 parts of flame-retardant PET-based copolyester, 0.8 parts of triglycidyl isocyanurate, and 4 parts of a compatibilizer are sequentially added into a blender, melt-extruded, and injection molded to obtain a high-strength PET bottle blank.

[0035] Comparative Example 3: A method for preparing a high-strength PET bottle blank, comprising the following steps: adding 120 parts of PET particles, 10 parts of toughened PET-based copolyester, 0.8 parts of triglycidyl isocyanurate, and 4 parts of a compatibilizer into a blender in sequence, melt-extruding, and injection molding to obtain a high-strength PET bottle blank.

[0036] Comparative Example 4: A method for preparing a high-strength PET bottle blank, comprising the following steps: 100 parts of PET particles, 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 a compatibilizer are sequentially added into a blender, melt-extruded, and injection molded to obtain a high-strength PET bottle blank.

[0037] Comparative Example 5: A method for preparing a high-strength PET bottle blank, comprising the following steps: adding 100 parts of PET particles, 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 a compatibilizer into a blender in sequence, melt-extruding, and injection molding to obtain a high-strength PET bottle blank.

[0038] Comparative Example 6: A method for preparing a high-strength PET bottle blank, comprising the following steps: adding 100 parts of PET particles, 10 parts of toughened PET-based copolyester, 20 parts of flame-retardant PET-based copolyester, and 0.8 parts of triglycidyl isocyanurate into a blender in sequence, melt-extruding, and injection molding to obtain a high-strength PET bottle blank.

[0039] Comparative Example 7: A method for preparing a high-strength PET bottle blank, comprising the following steps: adding 100 parts of PET particles, 10 parts of toughened PET-based copolyester, 30 parts of flame-retardant PET-based copolyester, and 0.8 parts of triglycidyl isocyanurate into a blender in sequence, melt-extruding, and injection molding to obtain a high-strength PET bottle blank.

[0040] Comparative Example 8: A method for preparing a high-strength PET bottle blank, comprising the following steps: adding 100 parts of PET particles, 20 parts of toughened PET-based copolyester, 20 parts of flame-retardant PET-based copolyester, and 0.8 parts of triglycidyl isocyanurate into a blender in sequence, melt-extruding, and injection molding to obtain a high-strength PET bottle blank.

[0041] Experiment: Determination of mechanical properties: According to GB / T 1040.3-2006, the polyester particles prepared by melt extrusion in the above embodiments and comparative examples were pressed into thin sheets with a thickness of 1 mm and a length and width of 150 mm×10 mm. The prepared samples were tested at a tensile speed of 100 mm / min using an electronic universal tensile testing machine. The experiment was repeated three times for each thin sheet sample, and the final result was expressed as an average value.

[0042] Determination of flame retardant properties: According to ASTM D2863-97, the polyester particles 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, and the limiting oxygen index (LOI) was measured. Each sheet sample was tested three times, and the final result was expressed as an average value. The polyester particles 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 130 mm×13 mm. The UL-94 test was performed using a CZF-2 instrument. The experiment was repeated three times for each sheet sample, and the final result was expressed as an average value.

[0043] The specific experimental results are shown in Table 1 below.

[0044] Table 1 Performance test data of high-strength PET bottle raw material polyester particles

[0045] Conclusion: The PET preform prepared by the present invention has excellent mechanical properties and flame retardant properties.

[0046] In Comparative Example 1, the flame-retardant PET-based copolyester was directly replaced with commercially available DOPO, resulting in reduced mechanical properties.

[0047] In Comparative Example 2, no toughening PET-based copolyester was added, resulting in reduced mechanical properties.

[0048] In Comparative Example 3, no flame retardant PET-based copolyester was added, resulting in reduced flame retardancy.

[0049] In Comparative Example 4, excessive toughening PET-based copolyester was added, resulting in reduced mechanical properties.

[0050] In Comparative Example 5, excessive amount of flame-retardant PET-based copolyester was added, resulting in reduced mechanical properties.

[0051] In Comparative Example 6, no compatibilizer was added, resulting in reduced mechanical properties and flame retardant properties.

[0052] In Comparative Example 7, the amount of flame-retardant PET-based copolyester added was increased without adding a compatibilizer, and the improvement effect was poorer than that of Example 2.

[0053] In Comparative Example 8, the amount of toughened PET-based copolyester added was increased without adding a compatibilizer, and the improvement effect was poorer than that of Example 3.

[0054] 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 present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A high-strength PET preform, characterized in that: The high-strength PET preform comprises the following components: PET particles, toughened PET-based copolyester, flame-retardant PET-based copolyester, chain extender, and compatibilizer; The toughened PET-based copolyester is prepared by copolymerizing an elastomer prepared from bisphenol A diglycidyl ether and sebacic acid with polyethylene terephthalate; The flame retardant PET-based copolyester is prepared by copolymerization of benzimidazole monomer and dimethyl terephthalate; The chain extender is any one of triglycidyl isocyanurate or 2,2'-(1,3-phenylene)-dioxazoline; The compatibilizer is prepared by reacting p-phenylenediamine, 4-hydroxybenzaldehyde and DOPO.

2. The high-strength PET preform according to claim 1, characterized in that: The proportions of the components in the high-strength PET bottle blank, by weight, include: 80-100 parts of PET particles, 10-20 parts of toughened PET-based copolyester, 20-30 parts of flame-retardant PET-based copolyester, 0.5-1 parts of chain extender, and 4-8 parts of compatibilizer.

3. The high-strength PET preform according to claim 2, characterized in that: The preparation method of the toughened PET-based copolyester comprises the following steps: Add sebacic acid to a reaction container, heat to 130-132°C to dissolve, cool to 124-125°C, add the dissolved sebacic acid to bisphenol A diglycidyl ether, keep warm and stir evenly, add 1,5,7-triazabicyclo[4.4.0]decene-5-ene, stir evenly, keep warm and react for 3-3.5h, heat to 160-162°C and react for 6-6.5h to obtain an elastomer; The elastomer is added to ethylene glycol, heated to 180-182°C to dissolve, and a mixed solution is obtained; terephthalic acid, ethylene glycol, and tetrabutyl titanate are added to a reaction container, heated to 260-265°C under a nitrogen atmosphere, and reacted until the amount of water collected reaches 90% of the theoretical amount required for producing the prepolymer, the mixed solution is added, heated to 280-285°C, and vacuum polycondensed, the product is poured into ice water, filtered, the precipitate is collected, and vacuum dried to obtain a toughened PET-based copolyester.

4. The high-strength PET preform according to claim 3, characterized in that: During 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 5-10wt% of the total mass of sebacic acid and bisphenol A diglycidyl ether.

5. The high-strength PET preform according to claim 3, characterized in that: The proportions of the various components in the preparation process of the toughened PET-based copolyester include, by mass, 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.

6. The high-strength PET preform according to claim 1, characterized in that: The preparation method of the flame-retardant PET-based copolyester comprises the following steps: Add sodium metabisulfite to a mixture of methyl 4-formylbenzoate, methyl 3,4-diaminobenzoate and N,N-dimethylformamide, stir evenly, heat to 130-135°C for reaction for 6-7h, pour the product into ice water, keep warm and stir for 2-3h, filter, collect the precipitate, wash with deionized water and ethyl acetate, and vacuum dry to obtain a benzimidazole monomer; Dimethyl terephthalate, ethylene glycol and benzimidazole monomers are added into a reaction container, heated to 180-182° C. under a nitrogen atmosphere, and tetrabutyl titanate is added to perform a temperature-programmed reaction to obtain a flame-retardant PET-based copolyester.

7. The high-strength PET preform according to claim 6, characterized in that: In the preparation process of benzimidazole, the molar ratio of sodium pyrosulfite: methyl 4-formylbenzoate: methyl 3,4-diaminobenzoate is 1:1:

1.

8. The high-strength PET preform according to claim 6, characterized in that: In the preparation process 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°C for 2.5-3h, reacting at 240-245°C for 1h, reducing the atmospheric pressure of the reaction system to 30Pa, heating to 260-265°C and reacting for 2.5h.

9. The high-strength PET preform according to claim 1, characterized in that: The preparation method of the compatibilizer comprises the following steps: Add p-phenylenediamine and 4-hydroxybenzaldehyde to anhydrous ethanol, heat to 40-42°C for reaction for 4-5h, add anhydrous ethanol solution of DOPO, heat to 65-66°C for reaction for 8-9h, filter, collect the precipitate, wash with anhydrous ethanol, and vacuum dry to obtain a compatibilizer; During the preparation of the compatibilizer, the molar ratio of p-phenylenediamine:4-hydroxybenzaldehyde:DOPO is 0.5:1:

1.

10. A method for preparing a high-strength PET bottle embryo, characterized in that: The method comprises the following steps: adding PET particles, toughened PET-based copolyester, flame-retardant PET-based copolyester, chain extender and compatibilizer into a mixer in sequence according to a predetermined ratio, melt-extruding and injection molding to obtain a high-strength PET preform.

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