High-strength pet bottle preform and method for producing the same

Abstract

The application relates to the field of packaging materials, in particular to a high-strength PET bottle blank and a preparation method thereof. The high-strength PET bottle blank comprises, in mass parts, at least: PET resin 90-130 parts, auxiliary polymer composition 5-12 parts, nano reinforcing phase 2-6 parts, crystallization regulator 0.5-1 part, thermal stabilizer 0.3-0.6 part and dispersant 0.2-0.5 part. The PET bottle blank material prepared by the application can not only significantly improve the mechanical strength and mechanical strength, but also can consider the long-term performance stability of the bottle blank material under complex environmental conditions, such as high-temperature storage, low-temperature impact, waterproof and moisture resistance or content corrosion and the like, so as to meet the comprehensive performance demand of the PET bottle blank under complex environment and ensure the application environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of packaging materials, and more particularly to a high-strength PET preform and a preparation method thereof. BACKGROUND

[0002] In recent years, with the increasing demand for lightweight, high-strength and sustainability of packaging containers in the food, beverage and daily chemical industries, polyethylene terephthalate (PET) material has become one of the mainstream materials for packaging liquid products due to its excellent mechanical properties, transparency and recyclability. Among them, the performance of PET preform, as an intermediate product for blow molding bottle, directly determines the mechanical strength, barrier property and shape stability of the final packaging bottle. At present, the high-strength PET preforms commonly seen in the market are mostly realized by material modification, structure design and process optimization, but there are still many technical limitations.

[0003] In order to improve the mechanical properties of PET preform, various means are usually adopted in the prior art for optimization. On the one hand, by adjusting the molecular weight and its distribution of PET resin, the inherent viscosity is improved, so as to enhance the intrinsic strength of the material. High-viscosity PET resin can form a more compact molecular chain structure during molding, which helps to improve the overall rigidity and deformation resistance of the preform. On the other hand, specific comonomers or additives, such as cyclohexane dimethanol or nano fillers, are introduced to improve the crystallization behavior and toughness of PET. In addition, optimizing injection molding process parameters, including mold temperature, cooling rate, injection pressure and holding time, etc., are also widely used to control the residual stress distribution and crystallinity inside the preform, thereby reducing defects and improving structural uniformity. Some technical solutions also attempt to give the preform additional barrier properties and mechanical support through multi-layer co-injection or surface coating technology.

[0004] Although the prior art has made certain progress in improving the strength of PET preform, there are still many technical problems to be solved in actual application. First of all, simply relying on increasing the viscosity of the resin often leads to increased material processing difficulty, prolonged injection molding cycle, and thus affects production efficiency and increases manufacturing cost. Secondly, the optimization space of process parameters is limited, and excessive pursuit of high strength may lead to stress concentration in the preform, which in turn may cause cracks or even breakage during subsequent blow molding or use. Furthermore, the existing technology still lacks systematic solutions for the long-term performance stability of the preform under complex environmental conditions, such as high-temperature storage, low-temperature impact, waterproof and moisture resistance, or content corrosion, etc. SUMMARY

[0005] In summary, achieving a significant improvement in the comprehensive mechanical properties of PET preforms while ensuring good processing performance remains a major challenge in current technological development. High-strength PET preforms have become a key research topic for those skilled in the art. Through in-depth research in this product field, the inventors have ultimately proposed a high-strength PET preform and its preparation method in this application. The PET preform material obtained in this application not only significantly improves its mechanical strength but also maintains long-term performance stability under complex environmental conditions, such as high-temperature storage, low-temperature impact, water and moisture resistance, and resistance to corrosion from contents. This meets the comprehensive performance requirements of PET preforms in complex environments, ensuring optimal application performance.

[0006] A high-strength PET preform, by weight, comprises at least the following raw materials: 90-130 parts PET resin, 5-12 parts auxiliary polymerization composition, 2-6 parts nano-reinforcing phase, 0.5-1 part crystallization regulator, 0.3-0.6 parts heat stabilizer, and 0.2-0.5 parts dispersant.

[0007] Preferably, the mass ratio of the PET resin, the auxiliary polymerization composition and the nano-reinforcing phase is (100~120):(6~10):(3~5).

[0008] More preferably, the mass ratio of the PET resin, the auxiliary polymerization composition and the nano-reinforcing phase is (100~110):(7~8):(3.5~4.5).

[0009] Most preferably, the mass ratio of the PET resin, the auxiliary polymerization composition, and the nano-reinforcing phase is 100:7.5:4.

[0010] Preferably, the auxiliary polymerization composition is a combination of ethylene-methyl acrylate-glycidyl methacrylate terpolymer and polymethyl methacrylate.

[0011] Preferably, the mass ratio of the ethylene-methyl acrylate-glycidyl methacrylate terpolymer to polymethyl methacrylate is (2~2.5):(2~4).

[0012] More preferably, the mass ratio of the ethylene-methyl acrylate-glycidyl methacrylate terpolymer to polymethyl methacrylate is 2:3.

[0013] More preferably, the ethylene-methyl acrylate-glycidyl methacrylate terpolymer is AX8900, which is from Arkema, France.

[0014] More preferably, the polymethyl methacrylate is SHINKOLITE® M-207, sourced from Mitsubishi Resin Corporation, Japan.

[0015] The auxiliary polymerization composition added in this application effectively enhances the overall performance of PET preforms. During processing, the two specific types of polymethyl methacrylate and ethylene-methyl acrylate-glycidyl methacrylate terpolymer can fully bond with PET molecules, forming a strong and tough interfacial bond, thereby significantly enhancing the mechanical strength and impact toughness of the preform. The rigid components in the composition effectively improve the heat resistance and dimensional stability of the product, while the flexible segments improve its low-temperature brittleness resistance. At the same time, by forming a dense microstructure, the composition enhances the preform's barrier properties against moisture, oils, and other substances, as well as its corrosion resistance, extending the packaging life. Ultimately, without significantly altering the inherent properties of PET, a comprehensive optimization of strength, toughness, and durability is achieved.

[0016] Preferably, the nano-reinforcing phase is at least one of nano-silica, nano-kaolin, nano-calcium carbonate, and nano-titanium dioxide.

[0017] More preferably, the nano-reinforcing phase is nano-silica or nano-calcium carbonate.

[0018] Most preferably, the nano-reinforcing phase is nano-silica.

[0019] Preferably, the average particle size of the nano-reinforcing phase is 50~200 nm.

[0020] More preferably, the average particle size of the nano-reinforcing phase is 50~120 nm.

[0021] More preferably, the crystallization regulator is a combination of sorbitol derivative HPN-20E and di(p-methylbenzyl)sorbitol GEL ALL MD.

[0022] Preferably, the mass ratio of the sorbitol derivative HPN-20E to di(p-methylbenzyl)sorbitol GEL ALL MD is (3~6):(1.5~2.5).

[0023] More preferably, the mass ratio of the sorbitol derivative HPN-20E to di(p-methylbenzyl)sorbitol GEL ALL MD is (4.5~5):(1.8~2).

[0024] Preferably, the heat stabilizer is tris(2,4-di-tert-butylphenyl) phosphite or pentaerythritol bis(di(2,4-di-tert-butylphenyl) phosphate).

[0025] More preferably, the heat stabilizer is tris(2,4-di-tert-butylphenyl) phosphite.

[0026] Preferably, the dispersant is at least one of polyethylene wax, ethylene-vinyl acetate copolymer wax, polyol fatty acid ester, and stearic acid complex ester.

[0027] More preferably, the dispersant is polyethylene wax or stearic acid composite ester.

[0028] Most preferably, the dispersant is polyethylene wax.

[0029] Preferably, the high-strength PET preform, by weight, further comprises: 3-10 parts of composite additives, 0.1-0.3 parts of lubricant, 0.3-0.6 parts of anti-hydrolysis agent, and 0.1-0.3 parts of anti-UV agent.

[0030] Preferably, the mass ratio of the PET resin to the composite additive is (100~120):(5~10).

[0031] More preferably, the mass ratio of the PET resin to the composite additive is (100~110):(6~8).

[0032] Preferably, the composite additive is a composition of diglycidyl terephthalate, trimethylolpropane triacrylate, and dibutyltin dilaurate.

[0033] Preferably, the mass ratio of the diglycidyl terephthalate, trimethylolpropane triacrylate, and dibutyltin dilaurate is (8~9.5):(1~2):(0.05~0.12).

[0034] More preferably, the mass ratio of the diglycidyl terephthalate, trimethylolpropane triacrylate and dibutyltin dilaurate is (8.5~9):(1.2~1.8):(0.05~0.08).

[0035] Most preferably, the mass ratio of the diglycidyl terephthalate, trimethylolpropane triacrylate, and dibutyltin dilaurate is 8.5:1.5:0.05.

[0036] Further addition of the aforementioned composite additives can effectively improve the overall performance of the preform without affecting the inherent properties of the PET matrix. By constructing strengthened intermolecular connections to repair and extend the molecular chain structure, the molecular weight and melt strength of the material are increased, resulting in a significant improvement in the mechanical properties of the final product, such as pressure resistance and rigidity. On the other hand, the active components in this system can participate in the formation of a stable network structure, further enhancing the interaction forces between molecular chains, thereby improving the preform's creep resistance and dimensional stability. Since all reactions are completed at the molecular level and the additives are highly compatible with PET, the defects that may be caused by introducing foreign phases are avoided. Through this efficient molecular modification and network strengthening effect, the PET preform achieves superior overall strength and durability while maintaining excellent processing performance and transparency.

[0037] Preferably, the lubricant is at least one selected from calcium stearate, glyceryl monostearate, ethylene bis-stearamide, stearic acid, and zinc stearate.

[0038] More preferably, the lubricant is a combination of glyceryl monostearate and stearic acid.

[0039] Preferably, the mass ratio of glyceryl monostearate to stearic acid is (2.5~4):(0.8~1.6).

[0040] More preferably, the mass ratio of the glyceryl monostearate to stearic acid is (3~3.5):(1~1.2).

[0041] Preferably, the anti-hydrolysis agent is polycarbodiimide or an oxazoline compound.

[0042] More preferably, the anti-hydrolysis agent is polycarbodiimide.

[0043] Preferably, the UV stabilizer is at least one of UV-326, UV-327, UV-3346 and Chimasorb 944.

[0044] More preferably, the UV stabilizer is UV-326 or UV-3346.

[0045] Most preferably, the UV stabilizer is UV-3346.

[0046] A method for preparing a high-strength PET preform includes the following steps: S1: Dehumidifying and drying PET resin to a moisture content ≤0.1%, then mixing PET resin with all raw materials except composite additives in a high-speed mixer, followed by adding composite additives and mixing to obtain a premix; S2: Adding the premix to a twin-screw extruder for melt blending and granulation, then cooling and pelletizing to obtain masterbatch; S3: Dehumidifying and drying the masterbatch again to ensure a moisture content ≤0.1%, then injection molding using a precision injection molding machine, and after pressure holding and cooling, sealing and storing the preform to obtain the final product.

[0047] Preferably, the preparation method of the high-strength PET preform specifically includes the following steps: S1: Dehumidify and dry the PET resin to a moisture content ≤0.1%, then put the PET resin and all other raw materials except the composite additive into a high-speed mixer and mix at 500~600 rpm for 15~25 min, then add the composite additive and mix for 3~5 min to obtain a premix; S2: Add the premix to a twin-screw extruder for melt blending and granulation, using a five-zone temperature range of 250℃ / 265℃ / 275℃ / 280℃ / 275℃, a die temperature of 270℃, and a screw speed of 200~240 rpm, then cool and granulate to obtain masterbatch; S3: Dehumidify and dry the masterbatch again to ensure a moisture content ≤0.1%, then injection mold it using a precision injection molding machine. After holding pressure and cooling, seal and store the preform to obtain the final product.

[0048] The beneficial effects of this application are:

[0049] 1. The PET preform material obtained in this application can not only significantly improve its mechanical strength and mechanical strength, but also take into account the long-term performance stability of the preform material under complex environmental conditions, such as high temperature storage, low temperature impact, waterproof and moisture resistance or contents corrosion, etc., to meet the comprehensive performance requirements of PET preforms in complex environments and ensure the application environment.

[0050] 2. The auxiliary polymerization composition added to the PET preform material in this application can connect with PET molecules to form a strong and tough interfacial bond, thereby significantly enhancing the mechanical strength and impact toughness of the preform. The rigid components in the composition effectively improve the product's heat resistance and dimensional stability, while the flexible segments improve its low-temperature brittleness resistance. Simultaneously, by forming a dense microstructure, the composition enhances the preform's barrier properties against moisture, oils, and other substances, as well as its corrosion resistance, extending packaging life. Ultimately, without significantly altering the inherent properties of PET, a comprehensive optimization of strength, toughness, and durability is achieved.

[0051] 3. The composite additives further added to the PET preforms in this application repair and extend the molecular chain structure by constructing strengthened intermolecular connections, increasing the molecular weight and melt strength of the material, resulting in a significant improvement in the mechanical properties of the final product, such as pressure resistance and rigidity. On the other hand, the active components in this system can participate in the formation of a stable network structure, further enhancing the interaction force between molecular chains, thereby improving the creep resistance and dimensional stability of the preforms. Attached Figure Description

[0052] Figure 1 This is a photograph of the high-strength PET preform prepared in Example 1 of this application. Detailed Implementation

[0053] Example 1

[0054] A high-strength PET preform, by weight, comprises at least the following raw materials: 100 parts PET resin, 7.5 parts auxiliary polymerization composition, 4 parts nano-reinforcing phase, 0.8 parts crystallization regulator, 0.4 parts heat stabilizer, 0.4 parts dispersant, 7 parts composite additive, 0.3 parts lubricant, 0.3 parts anti-hydrolysis agent, and 0.2 parts UV stabilizer.

[0055] The PET resin is PET 10098, sourced from DuPont, USA.

[0056] The auxiliary polymerization composition is a combination of ethylene-methyl acrylate-glycidyl methacrylate terpolymer and polymethyl methacrylate in a mass ratio of 2:3.

[0057] The ethylene-methyl acrylate-glycidyl methacrylate terpolymer is AX8900, sourced from Arkema, France; the polymethyl methacrylate is SHINKOLITE® M-207, sourced from Mitsubishi Resin Corporation, Japan.

[0058] The nano-reinforcing phase is nano-silica with an average particle size of 75 nm.

[0059] The crystallization regulator is a combination of sorbitol derivative HPN-20E and di(p-methylbenzyl)sorbitol GEL ALL MD in a mass ratio of 5:2.

[0060] Sorbitol derivative HPN-20E is from Milliken, Inc., USA; di(p-methylbenzyl)sorbitol GEL ALLMD is from Shin Nippon Rikka Co., Ltd.

[0061] The heat stabilizer is tris(2,4-di-tert-butylphenyl) phosphite; the dispersant is polyethylene wax, industrial grade, sourced from Tangyi Chemical in Jining, China.

[0062] The composite additive is a combination of diglycidyl terephthalate, trimethylolpropane triacrylate and dibutyltin dilaurate, in a mass ratio of 8.5:1.5:0.05.

[0063] The lubricant is a composition of glyceryl monostearate and stearic acid in a mass ratio of 3.5:1.

[0064] The hydrolysis inhibitor is polycarbodiimide, industrial grade, sourced from Jiangsu Runfeng Synthetic Technology, China; the UV inhibitor is UV-3346.

[0065] A method for preparing a high-strength PET preform includes the following steps: S1: Dehumidifying and drying PET resin to a moisture content ≤0.1%, then adding PET resin and all other raw materials except for composite additives into a high-speed mixer and mixing at 600 rpm for 20 min, followed by adding composite additives and mixing for 4 min to obtain a premix; S2: Adding the premix to a twin-screw extruder for melt blending and granulation, using five temperature zones (250℃ / 265℃ / 275℃ / 280℃ / 275℃), a die temperature of 270℃, and a screw speed of 220 rpm, followed by cooling and pelletizing to obtain masterbatch; S3: Dehumidifying and drying the masterbatch again to ensure a moisture content ≤0.1%, then injection molding using a precision injection molding machine, and after pressure holding and cooling, sealing and storing the preform to obtain the final product.

[0066] The actual high-strength PET preform obtained in this embodiment is shown in the image. Figure 1 As shown.

[0067] Example 2

[0068] This embodiment differs from Embodiment 1 only in the following aspects: A high-strength PET preform, by weight, comprises at least the following raw materials: 120 parts PET resin, 6.5 parts auxiliary polymerization composition, 5 parts nano-reinforcing phase, 0.8 parts crystallization regulator, 0.4 parts heat stabilizer, 0.4 parts dispersant, 7 parts composite additive, 0.3 parts lubricant, 0.3 parts anti-hydrolysis agent, and 0.2 parts UV stabilizer.

[0069] The auxiliary polymerization composition is a combination of ethylene-methyl acrylate-glycidyl methacrylate terpolymer and polymethyl methacrylate in a mass ratio of 2.5:4.

[0070] The remaining implementation methods are the same.

[0071] Example 3

[0072] This embodiment differs from Embodiment 1 only in the following aspects: A high-strength PET preform, by weight, comprises at least the following raw materials: 110 parts PET resin, 9.5 parts auxiliary polymerization composition, 3 parts nano-reinforcing phase, 0.8 parts crystallization regulator, 0.4 parts heat stabilizer, 0.4 parts dispersant, 8.5 parts composite additive, 0.3 parts lubricant, 0.3 parts anti-hydrolysis agent, and 0.2 parts UV stabilizer.

[0073] The composite additive is a combination of diglycidyl terephthalate, trimethylolpropane triacrylate and dibutyltin dilaurate, in a mass ratio of 9:1.2:0.06.

[0074] The remaining implementation methods are the same.

[0075] Comparative Example 1

[0076] This comparative example differs from Example 1 only in the following aspects: a high-strength PET preform, by weight, comprising at least the following raw materials: 100 parts PET resin, 2 parts auxiliary polymerization composition, 4 parts nano-reinforcing phase, 0.8 parts crystallization regulator, 0.4 parts heat stabilizer, 0.4 parts dispersant, 12.5 parts composite additive, 0.3 parts lubricant, 0.3 parts anti-hydrolysis agent, and 0.2 parts UV stabilizer.

[0077] The remaining implementation methods are the same.

[0078] Comparative Example 2

[0079] This comparative example differs from Example 1 only in the following aspects: a high-strength PET preform, by weight, comprising at least the following raw materials: 100 parts PET resin, 10.5 parts auxiliary polymerization composition, 4 parts nano-reinforcing phase, 0.8 parts crystallization regulator, 0.4 parts heat stabilizer, 0.4 parts dispersant, 1.5 parts composite additive, 0.3 parts lubricant, 0.3 parts anti-hydrolysis agent, and 0.2 parts UV stabilizer.

[0080] The remaining implementation methods are the same.

[0081] Comparative Example 3

[0082] This comparative example differs from Example 1 only in the following aspects: a high-strength PET preform, by weight, comprising at least the following raw materials: 80 parts PET resin, 12.5 parts auxiliary polymerization composition, 4 parts nano-reinforcing phase, 0.8 parts crystallization regulator, 0.4 parts heat stabilizer, 0.4 parts dispersant, 12 parts composite additive, 0.3 parts lubricant, 0.3 parts anti-hydrolysis agent, and 0.2 parts UV stabilizer.

[0083] The crystallization regulator is a combination of sorbitol derivative HPN-20E and di(p-methylbenzyl)sorbitol GEL ALL MD in a mass ratio of 8:1.

[0084] The remaining implementation methods are the same.

[0085] Comparative Example 4

[0086] This comparative example differs from Example 1 only in the following way: the auxiliary polymerization composition is a combination of ethylene-methyl acrylate-glycidyl methacrylate terpolymer and polymethyl methacrylate in a mass ratio of 5:1.

[0087] The remaining implementation methods are the same.

[0088] Comparative Example 5

[0089] This comparative example differs from Example 1 only in the following way: the auxiliary polymerization composition is a combination of ethylene-methyl acrylate-glycidyl methacrylate terpolymer and polymethyl methacrylate in a mass ratio of 0.5:4.5.

[0090] The remaining implementation methods are the same.

[0091] Comparative Example 6

[0092] The only difference between this comparative example and Example 1 is that the composite additive is a composition of diglycidyl terephthalate, trimethylolpropane triacrylate and dibutyltin dilaurate in a mass ratio of 9.5:0.5:0.05.

[0093] The remaining implementation methods are the same.

[0094] Comparative Example 7

[0095] The only difference between this comparative example and Example 1 is that the composite additive is a composition of diglycidyl terephthalate, trimethylolpropane triacrylate and dibutyltin dilaurate in a mass ratio of 4.5:5:0.05.

[0096] The remaining implementation methods are the same.

[0097] Performance testing

[0098] 1. Internal pressure resistance: Referring to standard GB / T 4546-2008, the prepared bottle preform is placed in an explosion-proof box, and compressed air is injected into the bottle at a constant rate through a pressurizing device until the bottle bursts. The pressure value at the time of bursting is recorded. Ten samples are tested for each sample group, and the average value is recorded in Table 1.

[0099] 2. High-temperature storage and aging resistance: Referring to standard GB / T 7141-2008, the prepared bottle preforms were placed at a constant temperature of 70℃ for 28 days and then taken out. They were cooled and conditioned for 24 hours in a standard laboratory environment and internal pressure resistance test was carried out to obtain the retention rate of internal pressure resistance. Ten samples were tested in each sample group and the average value was recorded in Table 1.

[0100] 3. Low temperature impact resistance: Referring to the standard GB / T 1843-2008, the prepared bottle preforms were pretreated at -18℃ for 24 hours, and then impact tests were quickly carried out using a pendulum impact testing machine. The strength retention rate was obtained by comparing the impact strength with that before the test. Ten samples were tested in each sample group, and the average value was recorded in Table 1.

[0101] 4. Waterproof and moisture-resistant: Referring to standard GB / T 1034-2008, the standard sample made from the bottle body was weighed and then immersed in a constant temperature water bath at 80℃ for 30 days. Afterwards, it was taken out, dried, and weighed again to calculate the water absorption rate. Ten samples were tested for each sample group, and the average value was recorded in Table 1.

[0102] 5. Corrosion resistance of contents: Referring to standard GB / T 11547-2008, the standard sample was completely immersed in soybean edible oil at 60℃ for 14 days. After that, it was taken out, cleaned with ethanol and dried. The dimensional change rate was tested. Ten samples were tested for each sample group, and the average value was recorded in Table 1.

[0103] 6. Drop resistance: Refer to standard GB / T 4857.5-2019. After filling the bottle preform with soybean edible oil and sealing it tightly, drop it freely from a test height of 2.2m with the bottom down onto a rigid ground. Check whether the bottle is broken or leaking. If there is no breakage or leakage, it is considered a pass; otherwise, it is considered a fail. 50 samples are tested in each group, and the pass rate is recorded in Table 1.

[0104] Table 1 Performance Test Results

[0105]

[0106] Based on the final examples and comparative performance test results, Examples 1-3, due to the addition of appropriate amounts of auxiliary polymerization composition and composite additives as specified in this application, enhanced the connection strength with PET molecules, forming a stronger interfacial bond. The rigid components and flexible segments respectively improved the heat resistance, dimensional stability, and low-temperature brittleness resistance of the products, and effectively strengthened the intermolecular connections to repair and extend the molecular chain structure, increasing the molecular weight and melt strength of the material. As a result, the mechanical properties of the final product, such as pressure resistance and rigidity, were significantly improved.

[0107] Comparative Examples 1-3, due to the lack of specific technical solutions, resulted in an imbalance in the effects of the polymer composition and composite additives in the PET system, failing to achieve their optimal performance and leading to a significant decline in corresponding properties. Comparative Examples 4-7, on the other hand, did not employ suitable selection and proportioning schemes for the polymer composition and composite additives, resulting in an inability to achieve optimal synergistic effects and ultimately impacting the final properties of the produced PET preforms.

Claims

1. A high-strength PET preform, characterized in that: By weight, the raw materials include: 90-130 parts PET resin, 5-12 parts auxiliary polymerization composition, 2-6 parts nano-reinforcing phase, 0.5-1 part crystallization regulator, 0.3-0.6 parts heat stabilizer, 0.2-0.5 parts dispersant, 3-10 parts composite additive, 0.1-0.3 parts lubricant, 0.3-0.6 parts anti-hydrolysis agent, and 0.1-0.3 parts UV stabilizer; The auxiliary polymerization composition is a combination of ethylene-methyl acrylate-glycidyl methacrylate terpolymer and polymethyl methacrylate, with a mass ratio of (2~2.5):(2~4). The crystallization regulator is a composition of sorbitol derivative HPN-20E and di(p-methylbenzyl)sorbitol GEL ALL MD, in a mass ratio of (3~6):(1.5~2.5). The mass ratio of the PET resin to the composite additive is (100~120):(5~10). The composite additive is a composition of diglycidyl terephthalate, trimethylolpropane triacrylate and dibutyltin dilaurate, in a mass ratio of (8~9.5):(1~2):(0.05~0.12).

2. The high-strength PET preform according to claim 1, characterized in that: The PET resin has an auxiliary polymerization composition and a nano-reinforcing phase in a mass ratio of (100~120):(6~10):(3~5).

3. The high-strength PET preform according to claim 2, characterized in that: The nano-reinforcing phase is at least one of nano-silica, nano-kaolin, nano-calcium carbonate, and nano-titanium dioxide.

4. The high-strength PET preform according to claim 3, characterized in that: The dispersant is at least one of polyethylene wax, ethylene-vinyl acetate copolymer wax, polyol fatty acid ester, and stearic acid complex ester.

5. The high-strength PET preform according to claim 4, characterized in that: The ethylene-methyl acrylate-glycidyl methacrylate terpolymer is AX8900; the polymethyl methacrylate is SHINKOLITE® M-207.

6. The high-strength PET preform according to claim 5, characterized in that: The anti-hydrolysis agent is a polycarbodiimide or an oxazoline compound.

7. A method for preparing a high-strength PET preform according to any one of claims 1 to 6, characterized in that: Includes the following steps: S1: Dehumidify and dry the PET resin until the moisture content is ≤0.1%. Then, put the PET resin and all other raw materials except the composite additive into a high-speed mixer and mix them. Then, add the composite additive and mix to obtain a premix. S2: Add the premix to a twin-screw extruder for melt blending and granulation. After melt blending, cool and granulate to obtain masterbatch. S3: Dehumidify and dry the masterbatch again to ensure the moisture content is ≤0.1%. Inject and mold it using a precision injection molding machine. After holding pressure and cooling, seal and store the preform to obtain the final product.

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