Highly transparent cold-resistant toughening agent for polyester material and preparation method thereof

Abstract

This invention relates to the field of toughening agent technology, specifically a high-transparency, cold-resistant toughening agent for polyester materials and its preparation method. By weight, it comprises 50-90 parts PET, 10-40 parts PETG, 1-10 parts high-transparency TPEE, 1-5 parts TPEE-g-MAH, 0.3-6 parts composite plasticizer, 0.1-0.5 parts nucleating agent, and 0.1-0.5 parts antioxidant. The preparation method includes: raw material drying, additive premixing, mixing the base material and additives, melt extrusion, and cooling pelletizing. This invention, through the synergistic effect of high-transparency TPEE and the specific compatibilizer TPEE-g-MAH, achieves nanoscale dispersion and strong interfacial bonding while solving the technical problem of "toughening inevitably reducing transparency" in traditional toughening materials. This results in a material with a low-temperature impact strength of 110-150 kJ / m² at -30°C, while maintaining a light transmittance ≥90% and a haze ≤2%. It is particularly suitable for PET products requiring high transparency and low-temperature impact resistance.

Description

Technical Field

[0001] This invention relates to the field of toughening agent technology, and in particular to a high-permeability, cold-resistant toughening agent for polyester materials and its preparation method. Background Technology

[0002] PET (polyethylene terephthalate) has become the mainstream material for existing plastic cups (including ice cups) due to its excellent light transmittance, high gloss, good food safety and easy processing and molding. It is widely used in the scenarios of cold drink serving, supermarket sales and home use.

[0003] However, PET material has a significant shortcoming in cold resistance. Its glass transition temperature is about 78℃. When the usage temperature drops below 0℃, especially in low-temperature environments of -10℃ to -20℃, it is prone to cracking when handled or squeezed, and breakage when holding cold drinks or dry ice. It cannot meet the needs of extreme low-temperature use, which has become the core pain point restricting the expansion of PET plastic cups in various applications.

[0004] The cracking and breakage of PET at -20℃ is mainly due to the deterioration of its mechanical properties at low temperatures caused by its molecular structure. PET is a semi-crystalline polyester with a certain degree of rigidity in its molecular chains. When the operating temperature drops to -20℃, which is far below the Tg temperature, the thermal motion of the molecular chain segments is greatly suppressed, the chain segment slippage is hindered, and the molecular chain changes from a "flexible state" to a "rigid glassy state". The flexibility decreases sharply and the brittleness increases significantly.

[0005] Some existing modified cold-resistant materials improve their low-temperature toughness by adding elastomers and compatibilizers to lower the glass transition temperature and brittle temperature. However, traditional elastomers (such as EPDM rubber, styrene-butadiene rubber, and ordinary EVA) are mostly opaque or semi-transparent materials. Adding them will significantly reduce the light transmittance of the blend system, and the haze often rises to more than 5%, which cannot meet the requirements of high-transparency ice cups.

[0006] Therefore, developing a toughening agent that can simultaneously impart excellent low-temperature toughness and high light transmittance to PET materials has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The primary objective of this invention is to overcome the shortcomings of existing technologies and provide a high-transparency, cold-resistant toughening agent for polyester materials. This toughening agent, when blended with a PET substrate, can significantly reduce the material's glass transition temperature and substantially improve its low-temperature impact strength while maintaining a high light transmittance of over 90% and a low haze of less than 2%, achieving a synergistic optimization of cold resistance and high transparency.

[0008] Another objective of this invention is to provide a method for preparing the aforementioned high-permeability, cold-resistant toughening agent. This method is simple, continuous, and easy to industrialize, effectively ensuring uniform dispersion and interfacial compatibility of the components, thereby ensuring the stability of the final product's performance.

[0009] The objective of this invention is achieved through the following technical solution: a high-permeability, cold-resistant, toughening agent for polyester materials, comprising the following components by weight: 50-90 parts of polyethylene terephthalate (PET); 10-40 parts of polyethylene terephthalate-1,4-cyclohexanediol ester (PETG); 1-10 parts of thermoplastic polyester elastomer (TPEE); 1-5 parts of maleic anhydride-grafted thermoplastic polyester elastomer (TPEE-g-MAH); The plasticizer comprises 0.3-6 parts, wherein the plasticizer is a compound of pentaerythritol tetrastearate (PETS), tristearate citrate (CTS), and polyglycerol fatty acid ester (PGFE), wherein the weight parts of pentaerythritol tetrastearate (PETS), tristearate citrate (CTS), and polyglycerol fatty acid ester (PGFE) are 0.1-2 parts, 0.1-2 parts, and 0.1-2 parts, respectively, and the compounding ratio of PETS:CTS:PGFE is 2:1:1; Nucleating agent 0.1-0.5 parts; Antioxidant 0.1-0.5 parts.

[0010] Another objective of this invention is achieved through the following technical solution: a method for preparing a high-permeability, cold-resistant toughening agent, comprising the following steps: S1. Drying: The raw materials are fed into a dryer and dried at 80-120℃ for 4-6 hours, controlling the moisture content to ≤0.05%; S2. Additive premixing: Plasticizer, nucleating agent and antioxidant are mixed in a high-speed mixer at a speed of 500-800 r / min for 3-5 minutes to obtain premixed additives; S3. Mixing the substrate and additives: Mix the premixed additives obtained in step S2 with the dried substrate in step S1 in a mixer at a speed of 800-1200 r / min for 8-10 minutes to obtain a mixture; S4. Melt extrusion: Add the mixture obtained in step S3 into a twin-screw extruder, control the barrel temperature at 200-285℃, control the die temperature at 220-270℃, and the vacuum degree ≤-0.5MPa for melt extrusion. S5. Cooling and pelletizing: The extruded filaments are cooled in a water bath at 25-35℃, and then cut into pellets with a diameter of 2-3mm by a pelletizer.

[0011] The present invention has the following advantages: 1. The high-transparency, cold-resistant toughening agent for polyester materials and its preparation method, by selecting optical-grade high-transparency TPEE as the core toughening component, which has a similar refractive index to PET / PETG substrate, and through the dual effects of structural homology and chemical bonding of the specially formulated compatibilizer TPEE-g-MAH, achieves nanoscale uniform dispersion of TPEE in the substrate, greatly reducing light scattering at the phase interface, so that the blended material can achieve an impact strength of 110-150kJ / m² at -30℃ while maintaining a light transmittance of over 90% and a haze of ≤2%.

[0012] 2. The high-permeability cold-resistant toughening agent for polyester materials and its preparation method possess extreme low-temperature cold resistance. The glass transition temperature of high-permeability TPEE is ≤-65℃ and the embrittlement temperature is ≤-75℃, which provides an excellent low-temperature toughness basis for this toughening agent. When combined with PETG, which has excellent low-temperature performance, and with compatibilizers and plasticizers, the glass transition temperature of the blend system is significantly reduced, allowing the material to maintain flexibility even in extreme environments of -40℃.

[0013] 3. The high-transparency cold-resistant toughening agent for polyester materials and its preparation method have excellent interfacial compatibility and stable mechanical properties. The TPEE-g-MAH compatibilizer not only has high light transmittance, but its TPEE skeleton is similar to the TPEE structure of the toughening agent. The MAH active groups can react with the PET end groups to form a strong interfacial bond, effectively preventing phase separation and ensuring the mechanical stability and durability of the material under low-temperature impact.

[0014] 4. This high-transparency, cold-resistant, and toughening agent for polyester materials and its preparation method, through the optimized compounding of composite plasticizers, improves the melt flowability of the blended system while ensuring high light transmittance. The entire preparation method has clear process parameters, continuous operation, and high production efficiency, making it very suitable for large-scale industrial applications. The main components selected, including PET, PETG, TPEE, plasticizers, nucleating agents, and antioxidants, all meet international food contact material standards such as FDA, are safe and non-toxic, and are suitable for the food packaging field. Detailed Implementation

[0015] The present invention will be further described below, but the scope of protection of the present invention is not limited to the following description.

[0016] Example 1: This embodiment provides a high-permeability, cold-resistant toughening agent for polyester materials, the raw materials of which, by weight, comprise: PET (intrinsic viscosity 0.80 dl / g): 80 parts; PETG (intrinsic viscosity 0.80 dl / g): 10 parts; High-transparency TPEE (Shore hardness D58): 8 parts; TPEE-g-MAH (grafting rate 1.0%): 2.5 parts; Pentaerythritol tetrastearate (PETS): 1 part; Tristearate citrate (CTS): 0.5 parts; Polyglycerol fatty acid ester (PGFE): 0.5 parts; Nucleating agent (aluminum salt of 2,2'-methylene-bis(4,6-di-tert-butylphenyl phosphate): 0.15 parts; Antioxidant 1010: 0.2 parts; Antioxidant 168: 0.1 parts.

[0017] Its preparation method includes the following steps: 1) Feed the raw materials into a dryer and dry them at 100℃ for 5 hours until the moisture content is ≤0.05%; 2) Put PETS, CTS, PGFE, nucleating agent, antioxidant 1010 and antioxidant 168 into a high-speed mixer and mix for 4 minutes at 600 r / min to obtain premixed additives; 3) The dried substrate from step 1 and the premixed additives obtained in step 2 are put into a high-speed mixer and mixed at 1000 r / min for 9 minutes to obtain a mixture; 4) The mixture is fed into a twin-screw extruder for melt extrusion. The extruder temperatures are set as follows: feeding section 160℃, melting section 240℃, reaction section 260℃, homogenization section 255℃, and die head 250℃; screw speed 250 r / min; vacuum degree in the vacuum devolatilization section -0.09 MPa. 5) The extruded melt filaments are cooled in a 30°C water bath and then pelletized to obtain toughening agent granules with uniform particle size.

[0018] Example 2: This embodiment provides a high-permeability, cold-resistant toughening agent for polyester materials, the raw materials of which, by weight, comprise: PET (intrinsic viscosity 0.80 dl / g): 80 parts; PETG (intrinsic viscosity 0.80 dl / g): 13 parts; High-transparency TPEE (Shore hardness D58): 5 parts; TPEE-g-MAH (grafting rate 1.0%): 2.5 parts; Pentaerythritol tetrastearate (PETS): 1 part; Tristearate citrate (CTS): 0.5 parts; Polyglycerol fatty acid ester (PGFE): 0.5 parts; Nucleating agent (aluminum salt of 2,2'-methylene-bis(4,6-di-tert-butylphenyl phosphate): 0.15 parts; Antioxidant 1010: 0.2 parts; Antioxidant 168: 0.1 parts; The preparation method is the same as in Example 1.

[0019] Example 3: This embodiment provides a high-permeability, cold-resistant toughening agent for polyester materials, the raw materials of which, by weight, comprise: PET (intrinsic viscosity 0.80 dl / g): 80 parts; PETG (intrinsic viscosity 0.80 dl / g): 8 parts; High-transparency TPEE (Shore hardness D58): 10 parts; TPEE-g-MAH (grafting rate 1.0%): 2.5 parts; Pentaerythritol tetrastearate (PETS): 1 part; Tristearate citrate (CTS): 0.5 parts; Polyglycerol fatty acid ester (PGFE): 0.5 parts; Nucleating agent (aluminum salt of 2,2'-methylene-bis(4,6-di-tert-butylphenyl phosphate): 0.15 parts; Antioxidant 1010: 0.2 parts; Antioxidant 168: 0.1 parts; The preparation method is the same as in Example 1.

[0020] Comparative Example 1: This comparative example provides a comparative material, the raw materials of which, by weight, comprise: PET (intrinsic viscosity 0.80 dl / g): 80 parts; PETG (intrinsic viscosity 0.80 dl / g): 20 parts; High-transparency TPEE (Shore hardness D58): 0 parts; TPEE-g-MAH (grafting rate 1.0%): 0 copies; Pentaerythritol tetrastearate (PETS): 1 part; Tristearate citrate (CTS): 0.5 parts; Polyglycerol fatty acid ester (PGFE): 0.5 parts; Nucleating agent (aluminum salt of 2,2'-methylene-bis(4,6-di-tert-butylphenyl phosphate): 0.15 parts; Antioxidant 1010: 0.2 parts; Antioxidant 168: 0.1 parts; The preparation method is the same as in Example 1.

[0021] Comparative Example 2: This comparative example provides a comparative material, the raw materials of which, by weight, comprise: PET (intrinsic viscosity 0.80 dl / g): 80 parts; PETG (intrinsic viscosity 0.80 dl / g): 13 parts; EVA (alternative to high-transparency TPEE): 5 parts; TPEE-g-MAH (grafting rate 1.0%): 2.5 parts; Pentaerythritol tetrastearate (PETS): 1 part; Tristearate citrate (CTS): 0.5 parts; Polyglycerol fatty acid ester (PGFE): 0.5 parts; Nucleating agent (aluminum salt of 2,2'-methylene-bis(4,6-di-tert-butylphenyl phosphate): 0.15 parts; Antioxidant 1010: 0.2 parts; Antioxidant 168: 0.1 parts; The preparation method is the same as in Example 1.

[0022] Comparative Example 3: This comparative example provides a comparative material, the raw materials of which, by weight, comprise: PET (intrinsic viscosity 0.80 dl / g): 80 parts; PETG (intrinsic viscosity 0.80 dl / g): 13 parts; SBR (an alternative to high-transparency TPEE): 5 parts; TPEE-g-MAH (grafting rate 1.0%): 2.5 parts; Pentaerythritol tetrastearate (PETS): 1 part; Tristearate citrate (CTS): 0.5 parts; Polyglycerol fatty acid ester (PGFE): 0.5 parts; Nucleating agent (aluminum salt of 2,2'-methylene-bis(4,6-di-tert-butylphenyl phosphate): 0.15 parts; Antioxidant 1010: 0.2 parts; Antioxidant 168: 0.1 parts; The preparation method is the same as in Example 1.

[0023] Comparative Example 4: This comparative example provides a comparative material, the raw materials of which, by weight, comprise: PET (intrinsic viscosity 0.80 dl / g): 80 parts; PETG (intrinsic viscosity 0.80 dl / g): 13 parts; EPDM (alternative to high-transparency TPEE): 5 parts; TPEE-g-MAH (grafting rate 1.0%): 2.5 parts; Pentaerythritol tetrastearate (PETS): 1 part; Tristearate citrate (CTS): 0.5 parts; Polyglycerol fatty acid ester (PGFE): 0.5 parts; Nucleating agent (aluminum salt of 2,2'-methylene-bis(4,6-di-tert-butylphenyl phosphate): 0.15 parts; Antioxidant 1010: 0.2 parts; Antioxidant 168: 0.1 parts; The preparation method is the same as in Example 1.

[0024] Comparative Example 5: This comparative example provides a comparative material, the raw materials of which, by weight, comprise: PET (intrinsic viscosity 0.80 dl / g): 80 parts; PETG (intrinsic viscosity 0.80 dl / g): 10 parts; High-transparency TPEE (Shore hardness D58): 8 parts; EMA-g-GMA (replaces TPEE-g-MAH): 2.5 parts; Pentaerythritol tetrastearate (PETS): 1 part; Tristearate citrate (CTS): 0.5 parts; Polyglycerol fatty acid ester (PGFE): 0.5 parts; Nucleating agent (aluminum salt of 2,2'-methylene-bis(4,6-di-tert-butylphenyl phosphate): 0.15 parts; Antioxidant 1010: 0.2 parts; Antioxidant 168: 0.1 parts; The preparation method is the same as in Example 1.

[0025] The test results of the implementation plan are shown in the table below: parameter Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Melting point / °C 232 233 231 243 240 241 238 235 Glass transition temperature / °C 64 66 63 75 73 74 71 68 <![CDATA[-30 °C low temperature impact strength KJ / m 2 > 140 135 150 35 65 50 100 125 transmittance / % 90.2 90.5 90 91 73 61 49 83 Haze / % 1.9 1.6 2.3 0.5 42 56 62 6 As shown in the table above, Examples 1, 2, and 3 exhibit excellent low-temperature resistance. Increasing the elastomer content improves the cold resistance of the materials to some extent, but it slightly reduces transparency and increases haze. Considering both low-temperature resistance and transparency, Example 1 achieves good light transmittance while maintaining good low-temperature resistance, resulting in a better overall effect. The proportions in Example 1 are more suitable. In Comparative Example 1, the low-temperature resistance dropped sharply after the elastomer and compatibilizer components were removed. This indicates that although ordinary PET / PETG materials have certain low-temperature toughness, they cannot adapt to storage and transportation environments at -20°C or even -30°C, which is consistent with the current problem of PET materials being intolerant to low temperatures. After modification, Example 1 has better low-temperature resistance and higher transparency. In Comparative Example 2, TPEE in Example 2 was replaced with EVA; in Comparative Example 3, TPEE in Example 2 was replaced with SBR; and in Comparative Example 4, TPEE in Example 2 was replaced with EPDM. Other components remained the same as in Example 2. As shown in the table above, the low-temperature resistance of the elastomer-modified material was improved to some extent, with the low-temperature resistance ranking as follows: EPDM modification > EVA modification > SBR modification. However, when adding the same 5 components, the transparency decreased sharply, and the haze increased significantly, failing to achieve a high-transparency appearance. Furthermore, compared to Example 2, the low-temperature resistance was far lower than that of the TPEE-modified material, indicating that the addition of traditional elastomers significantly reduces the light transmittance of the blend system, and the improvement in low-temperature resistance is far less than that of modified TPEE. Therefore, this high-transparency modified TPEE is more suitable. In Comparative Example 5, the compatibilizer in Example 1 was replaced with EMA-g-GMA, while other components remained the same as in Example 1. As shown in the table above, the compatibilizer EMA-g-GMA also showed good low-temperature resistance, which was slightly weaker than that of Example 1 using TPEE-g-MAH compatibilizer. However, at the same addition amount, the GMA-grafted compatibilizer would significantly reduce the light transmittance of the system and cause the haze to soar to over 5%. This result indicates that TPEE-g-MAH is a more suitable compatibilizer. The above comparison results show that the modified high-permeability TPEE is selected as the cold-resistant and high-permeability material, TPEE-g-MAH is selected as the compatibilizer, and the proportion of each component is selected as the proportion of Example 1. This can ensure cold resistance and toughness while retaining the high permeability characteristics.

[0026] In summary, this invention, by selecting optical-grade high-transmittance TPEE as the core toughening component, whose refractive index is similar to that of PET / PETG substrates, and through the dual effects of structural homology and chemical bonding of the specially formulated compatibilizer TPEE-g-MAH, achieves nanoscale uniform dispersion of TPEE in the substrate, greatly reducing light scattering at the phase interface. This allows the blended material to achieve an impact strength of 110-150 kJ / m² at -30℃ while maintaining a transmittance of over 90% and a haze of ≤2%, exhibiting exceptional low-temperature resistance. The high-transmittance TPEE has a glass transition temperature ≤-65℃ and a brittleness temperature ≤-75℃, providing a foundation for the excellent low-temperature toughness of this toughening agent. Synergistically combining it with PETG, which has excellent low-temperature performance, and working in conjunction with compatibilizers and plasticizers, significantly reduces the glass transition temperature of the blended system, enabling the material to achieve... It maintains flexibility even in extreme environments of -40℃, exhibits excellent interfacial compatibility, and stable mechanical properties. The TPEE-g-MAH compatibilizer not only possesses high light transmittance, but its TPEE skeleton is also structurally similar to that of the toughening agent TPEE. The MAH active groups can react with the PET end groups to form a strong interfacial bond, effectively preventing phase separation and ensuring the mechanical stability and durability of the material under low-temperature impact. Through optimized compounding of the composite plasticizer, while ensuring high light transmittance, the melt flowability of the blend system is improved. The entire preparation method has clear process parameters, continuous operation, and high production efficiency, making it very suitable for large-scale industrial applications. The main components selected—PET, PETG, TPEE, plasticizer, nucleating agent, and antioxidant—all comply with international food contact material standards such as the FDA, are safe and non-toxic, and are suitable for the food packaging field.

[0027] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-permeability, cold-resistant toughening agent for polyester materials, characterized in that: By weight, it includes the following components: 50-90 parts of polyethylene terephthalate (PET); 10-40 parts of polyethylene terephthalate-1,4-cyclohexanediol ester (PETG); 1-10 parts of thermoplastic polyester elastomer (TPEE); 1-5 parts of maleic anhydride-grafted thermoplastic polyester elastomer (TPEE-g-MAH); The plasticizer comprises 0.3-6 parts, wherein the plasticizer is a compound of pentaerythritol tetrastearate (PETS), tristearate citrate (CTS), and polyglycerol fatty acid ester (PGFE), wherein the weight parts of pentaerythritol tetrastearate (PETS), tristearate citrate (CTS), and polyglycerol fatty acid ester (PGFE) are 0.1-2 parts, 0.1-2 parts, and 0.1-2 parts, respectively, and the compounding ratio of PETS:CTS:PGFE is 2:1:1; Nucleating agent 0.1-0.5 parts; Antioxidant 0.1-0.5 parts.

2. The high-permeability, cold-resistant toughening agent for polyester materials according to claim 1, characterized in that: The intrinsic viscosity of the PET is 0.80±0.02 dl / g, the melting point is 243-248℃, the acetaldehyde content is ≤1ppm, and the light transmittance is ≥90%; the intrinsic viscosity of the PETG is 0.78-0.82 dl / g, the glass transition temperature is 80-85℃, the light transmittance is ≥91%, and the haze is ≤1.0%.

3. The high-permeability, cold-resistant toughening agent for polyester materials according to claim 1, characterized in that: The nucleating agent is 2,2'-methylene-bis(4,6-di-tert-butylphenyl phosphate) aluminum salt, with an effective content ≥99.8% and a melting point >210℃; the antioxidant is a compound of antioxidant 1010 and antioxidant 168, with a compounding ratio of 2:

1.

4. The high-permeability, cold-resistant toughening agent for polyester materials according to claim 1, characterized in that: The plasticizer has a light transmittance of ≥91%, a haze of ≤0.5%, a migration rate of ≤0.3%, and meets FDA food contact standards.

5. A method for preparing the high-permeability, cold-resistant toughening agent according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Drying: The raw materials are fed into a dryer and dried at 80-120℃ for 4-6 hours, controlling the moisture content to ≤0.05%; S2. Additive premixing: Plasticizer, nucleating agent and antioxidant are mixed in a high-speed mixer at a speed of 500-800 r / min for 3-5 minutes to obtain premixed additives; S3. Mixing the substrate and additives: Mix the premixed additives obtained in step S2 with the dried substrate in step S1 in a mixer at a speed of 800-1200 r / min for 8-10 minutes to obtain a mixture; S4. Melt extrusion: Add the mixture obtained in step S3 into a twin-screw extruder, control the barrel temperature at 200-285℃, control the die temperature at 220-270℃, and the vacuum degree ≤-0.5MPa for melt extrusion. S5. Cooling and pelletizing: The extruded filaments are cooled in a water bath at 25-35℃, and then cut into pellets with a diameter of 2-3mm by a pelletizer.

6. The method for preparing a high-permeability, cold-resistant toughening agent according to claim 5, characterized in that: In step S4, the screw speed of the twin-screw extruder is 200-300 r / min, and the material residence time is 3-5 minutes. The melt extrusion process in step S4 includes a vacuum devolatilization step, with the vacuum level controlled at -0.08 to -0.1 MPa to remove unreacted monomers and byproducts; In step S5, the water temperature in the cooling water tank is 25-35℃, the pelletizer speed is 800-1200 r / min, and the particle length deviation is ≤±0.2mm. The plasticizer contains PETS, CTS and PGFE in a compound ratio of 2:1:

1. The antioxidant is a compound of antioxidant 1010 and antioxidant 168 in a 2:1 ratio, and the total amount added is 0.2-0.4 parts.

7. The method for preparing a high-permeability, cold-resistant toughening agent according to claim 5, characterized in that: The synthesis of the TPEE includes the following steps: S1. Prepolymerization reaction: Terephthalic acid (PTA), ethylene glycol (EG) and polytetrahydrofuran ether glycol (PTMG) are added to an esterification reactor in proportion, a composite catalyst is added, and the esterification reaction is carried out at 220℃ and 0.1-0.3MPa pressure until the esterification rate is ≥95% to obtain the prepolymer. The composite catalyst includes tetrabutyl titanate (TBOT) added at an amount of 0.01%-0.03% of the total mass of the monomers, and antimony glycolate as an auxiliary catalyst; S2. Polycondensation reaction: The prepolymer is transferred to a polycondensation reactor and polycondensation reaction is carried out under a vacuum of ≤100Pa and a temperature of 250-265℃. The reaction is carried out in stages, first at 250℃ for 1 hour, and then at 265℃ until the melt viscosity reaches 1.2-1.5dL / g. S3. Post-processing: The polycondensation product is subjected to devolatilization at a temperature of 240-250℃ and a vacuum of 50-80Pa. Then, antioxidants are added for stabilization. Finally, the product is granulated underwater with the cooling water temperature controlled at 40-50℃.

8. The method for preparing a high-permeability, cold-resistant toughening agent according to claim 7, characterized in that: The TPEE has a glass transition temperature ≤ -65℃, a embrittlement temperature ≤ -75℃, a low-temperature impact strength ≥ 130kJ / m² at -30℃, an elongation at break ≥ 550%, a light transmittance ≥ 91%, and a haze ≤ 0.8%.

9. The method for preparing a high-permeability, cold-resistant toughening agent according to claim 5, characterized in that: The grafting of TPEE-g-MAH includes the following steps: S1. Raw material pretreatment and mixing: Dry the TPEE substrate particles at 80-100℃ for 2-3 hours, and then mix them with maleic anhydride, initiator dicumyl peroxide (DCP) and antioxidant compound for 3-5 minutes to obtain a premix. The amount of maleic anhydride added is 2-4 parts by weight of TPEE, the amount of DCP added is 0.1-0.3 parts, and the antioxidant compound includes antioxidant 1010 and antioxidant 168 in a 2:1 ratio, with a total addition amount of 0.1-0.2 parts. S2. Melt Extrusion Grafting Reaction: The premixed material is melt-grafted using a twin-screw extruder. The extruder temperature is controlled in stages: feeding section 160-180℃, melting section 190-200℃, reaction section 210-230℃, homogenization section 200-210℃, and die head 190-200℃; screw speed 200-300 r / min, material residence time 3-5 minutes, and vacuum devolatilization is initiated after the reaction section, with a vacuum degree of -0.08 to -0.1 MPa. S3. Post-processing: The extruded melt is granulated underwater, cooled in water at 40-50℃, and then screened to obtain TPEE-g-MAH particles.

10. The method for preparing a high-permeability, cold-resistant toughening agent according to claim 9, characterized in that: The grafting rate of the TPEE-g-MAH is 0.8%-1.2%, the light transmittance is ≥90%, the haze is ≤0.6%, the melting point is 165-175℃, and the thermal decomposition temperature is ≥300℃.