Low-viscosity high-transparency PET composite material and preparation method thereof

Abstract

The present application belongs to the technical field of polymer materials, and particularly relates to a low-viscosity high-transparency PET composite material and a preparation method thereof. The present application aims at the problem that high transparency and high fluidity of PET materials in the prior art are difficult to be considered simultaneously, and provides a low-viscosity high-transparency PET composite material and a preparation method thereof, which comprises 80-100 parts of PET resin, 10-20 parts of PCTG resin, 0.2-0.6 parts of a modified nucleating agent, 5-10 parts of a toughening compatilizer, 0.3-0.5 parts of a lubricant and 0.3-0.5 parts of an antioxidant. The present application constructs a composite material with PET resin and PCTG resin as base resins, and by adding auxiliary agents such as a modified nucleating agent, a toughening compatilizer and a lubricant, the composite material has high transparency and low viscosity, and also has high brightness, high toughness and other characteristics.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a low-viscosity, high-permeability PET composite material and its preparation method. Background Technology

[0002] Polyethylene terephthalate (PET) is widely used in fibers, packaging containers, and engineering plastics due to its excellent mechanical properties, chemical resistance, and good light transmittance. Especially in the beverage, food, and cosmetics packaging industries, high transparency directly showcases the purity of the contents, enhancing consumer confidence and representing one of PET's core commercial value attributes. However, in injection molding, particularly in the production of thin-walled, precision, and complex structures, the melt flowability, or viscosity, directly determines molding accuracy, production efficiency, and finished product yield. Under current technological systems, it is often difficult to simultaneously achieve high transparency and high flowability (low viscosity) in PET materials.

[0003] For example, a Chinese invention patent application discloses a high heat-resistant and high light-transmitting PET film [application number: 202111677140.9]. This invention application includes: 20-28 parts of polyethylene terephthalate, 8-10 parts of polyethylene naphthalate, 8-16 parts of polyethylene, 6-10 parts of polyurethane dispersion, 2-6 parts of sodium tripolyphosphate, 2-4 parts of antioxidant, 2-4 parts of polyacrylate resin, 2-5 parts of heat stabilizer, 2-4 parts of curing agent, 2-4 parts of coupling agent, 3-5 parts of polypropylene, 2-5 parts of polyethylene glycol, and 3-30 parts of inorganic nanoparticles.

[0004] This invention application improves the transparency of PET resin by adding high-viscosity polyacrylate resin. Although the viscosity is adjusted by adding polyethylene and polyethylene glycol, the effect is still limited and cannot achieve the expected effect of having high transparency and low viscosity at the same time. Summary of the Invention

[0005] The purpose of this invention is to address the above-mentioned problems by providing a low-viscosity, high-permeability PET composite material.

[0006] Another objective of this invention is to provide a method for preparing a low-viscosity, high-permeability PET composite material to address the aforementioned problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solutions: A low-viscosity, high-permeability PET composite material comprises 80-100 parts by weight of PET resin, 10-20 parts by weight of PCTG resin, 0.2-0.6 parts by weight of a modifying nucleating agent, 5-10 parts by weight of a toughening compatibilizer, 0.3-0.5 parts by weight of a lubricant, and 0.3-0.5 parts by weight of an antioxidant.

[0008] In the aforementioned low-viscosity, high-permeability PET composite material, the modified nucleating agent is an HFE-ZnNa nucleating agent, which is prepared by the following method: Step 1: Add NA-50 and tetrahydrofuran to the reactor and stir to form a suspension. Under the condition of cooling in an ice-water bath, add hydrochloric acid solution dropwise. After the addition is complete, remove the ice-water bath and stir the mixture at 20-30℃ for 8-12 hours. After the reaction is complete, remove the tetrahydrofuran by vacuum distillation to obtain a white solid. Wash with deionized water to completely remove water-soluble impurities such as aluminum chloride. After drying, obtain the activated hydroxyphosphate intermediate (H-NA) for later use. Step 2: Under a nitrogen atmosphere, the prepared activated hydroxyphosphate intermediate is dissolved in tetrahydrofuran, and then 2,2,2-trifluoroethanol, anhydrous triethylamine and N,N'-dicyclohexylcarbodiimide are added sequentially. The reaction is carried out at 0-10℃ for 40-80 min, and then the temperature is raised to 20-30℃ and stirred for 8-12 h. After the reaction is completed, the mixture is filtered to remove byproducts. The filtrate is poured into ice water under stirring to precipitate. The solid is collected by vacuum filtration. The filter cake is then washed sequentially with ice water, dilute hydrochloric acid and ice water to remove residual alkali and condensing agent. The product is dried to obtain the monofluorinated nucleating agent precursor (F-NA) for later use. Step 3: Disperse the monofluorinated nucleating agent precursor obtained in Step 2 in an aqueous solution of tetrahydrofuran, heat to 40-60℃, and then add an aqueous solution of zinc acetate monohydrate and anhydrous sodium acetate dropwise under stirring. After the addition is complete, maintain the reaction at 50-60℃ for 6-10 hours. During the reaction, the solid color can be observed to gradually change from white to light yellow. After the reaction is complete, filter while hot, and wash the filter cake with deionized water at 40-50℃ until the washing liquid is neutral. Dry the light yellow solid to obtain HFE-ZnNa nucleating agent (hydroxyfluorinated ester zinc phosphate sodium sodium).

[0009] NA-50 nucleating agent, namely 2,2'-methylene-bis(4,6-di-tert-butylphenylphosphine) basic aluminum, is prone to agglomeration during processing when used as a nucleating agent. At the same time, as an inert filler, it is prone to slow migration and re-agglomeration during long-term use or heating, resulting in a decrease in transparency over time.

[0010] Therefore, this invention further modifies the NA-50 nucleating agent. After exposing its phosphate hydroxyl groups through acid hydrolysis, it is coupled with a small amount of 2,2,2-trifluoroethanol, causing some of the phosphate hydroxyl groups to dehydrate and condense, attaching a fluorinated group (-OCH2CF3) to reduce surface energy. Then, ion exchange is performed to construct a zinc-sodium dual ion center. Since the amount of 2,2,2-trifluoroethanol is insufficient, some of the phosphate hydroxyl groups can be used for esterification fixation with the end groups of PET or PCTG, avoiding the problem of nucleating agent molecule migration and aggregation during long-term use.

[0011] In the aforementioned low-viscosity, high-permeability PET composite material, the hydrochloric acid solution in step one is 0.5 mol / L, and the dropping time is 30 min.

[0012] In the aforementioned low-viscosity, high-permeability PET composite material, the molar ratio of the activated hydroxyphosphate intermediate, 2,2,2-trifluoroethanol, anhydrous triethylamine, and N,N'-dicyclohexylcarbodiimide added in step two is 1:1.1:1.5:1.2.

[0013] In the aforementioned low-viscosity, high-permeability PET composite material, the molar ratio of zinc acetate monohydrate and anhydrous sodium acetate added in step three is 1:2.

[0014] In the aforementioned low-viscosity, high-permeability PET composite material, the toughening compatibilizer is maleic anhydride-grafted POE.

[0015] In the aforementioned low-viscosity, high-permeability PET composite material, the grafting rate of maleic anhydride-grafted POE is 0.6%-1.0%.

[0016] In the aforementioned low-viscosity, high-permeability PET composite material, the lubricant is pentaerythritol tetrastearate. Pentaerythritol tetrastearate effectively reduces friction between the melt and the mold during processing, resulting in a smooth and glossy surface on the finished product.

[0017] In the aforementioned low-viscosity, high-permeability PET composite material, the antioxidant is antioxidant 1010.

[0018] A method for preparing the above-mentioned low-viscosity, high-permeability PET composite material includes the following steps: Step 1: Dry the PET resin and PCTG resin in an oven at 120-140℃ for 4-6 hours to obtain dried PET resin and dried PCTG resin. Step 2: Add the modified nucleating agent, toughening compatibilizer, lubricant, antioxidant, and the dried PET resin obtained in Step 1 to a high-speed mixer. After thorough mixing, add the mixture to a twin-screw extruder for heating and melting. Then, add the dried PCTG resin obtained in Step 1 to the twin-screw extruder via side feeding. After the molten material is extruded through the die head, it is granulated using water-cooled stringing or underwater pelletizing to obtain a low-viscosity, high-permeability PET composite material.

[0019] Preferably, the temperature from the main feed to the compression section of the twin-screw extruder is maintained at 250℃-260℃, and the temperature from the side feed to the die head section is maintained at 220℃-230℃.

[0020] Compared with existing technologies, the advantages of this invention are: 1. This invention constructs a composite material with PET resin and PCTG resin as the matrix resin, and by adding modifiers, nucleating agents, toughening compatibilizers, lubricants and other additives, the composite material has the characteristics of high transparency and low viscosity, as well as high gloss and toughness.

[0021] 2. The nucleating agent used in this invention is HFE-ZnNa nucleating agent, which is obtained by further modification of NA-50 nucleating agent. By introducing asymmetric fluorinated ethoxy groups, the molecular surface energy is significantly reduced, avoiding the problem of nucleating agent agglomeration in the melt. At the same time, the metal center is designed as a zinc-sodium bimetallic center. Sodium ions can form stable ion clusters at high temperatures, which can efficiently adsorb and orderly arrange PET molecular chains to form extremely high-density pre-nucleation sites. Zinc ions have a strong coordination ability with carbonyl groups in PET chain segments and can be used as a molecular template to directly guide PET chain segments to fold and fuse rapidly and orderly around them. Because it is a crystal, HFE-ZnNa nucleating agent, compared to the single aluminum ion metal center used in NA-50 nucleating agent, can effectively increase the nucleation density, thereby improving the transparency of the composite material. In addition, HFE-ZnNa nucleating agent also retains active hydroxyl groups, which can undergo in-situ transesterification reaction with the end groups of PET or PCTG at high processing temperatures. This anchors the nucleating agent molecules to the polymer backbone through chemical bonds, thus completely eliminating the migration and secondary aggregation of the nucleating agent in the later stages. It achieves permanent stable dispersion at the molecular level and avoids the problem that NA-50 nucleating agent will slowly migrate and re-aggregate when the product is used for a long time or heated, resulting in a decrease in transparency over time.

[0022] 3. The present invention uses maleic anhydride grafted with POE to toughen the composite material. Compared with the existing technology of adding glass fiber, it can avoid the problem of glass fiber damaging the transparency of the composite material and increasing the melt viscosity of the composite material. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to specific embodiments.

[0024] Example 1

[0025] This embodiment provides a low-viscosity, high-permeability PET composite material and its preparation method. The low-viscosity, high-permeability PET composite material comprises 80 parts by weight of PET resin, 20 parts by weight of PCTG resin, 0.6 parts by weight of HFE-ZnNa nucleating agent, 10 parts by weight of maleic anhydride-grafted POE with a grafting rate of 1.0%, 0.5 parts by weight of pentaerythritol tetrastearate, and 0.5 parts by weight of antioxidant 1010.

[0026] The HFE-ZnNa nucleating agent is prepared by the following method: Step 1: Add 10g of NA-50 and 150ml of tetrahydrofuran to the reactor and stir to form a suspension. Under the condition of cooling in an ice-water bath, add 80ml of 0.5mol / L hydrochloric acid solution dropwise. The addition is completed in 30min. Then remove the ice-water bath and stir the mixture at 30℃ for 12h. After the reaction is completed, remove the tetrahydrofuran by vacuum distillation to obtain a white solid. Wash with deionized water and dry to obtain the activated hydroxyphosphate intermediate for later use. Step 2: Under a nitrogen atmosphere, 8.5 g of the prepared activated hydroxyphosphate intermediate was dissolved in tetrahydrofuran, and then 2,2,2-trifluoroethanol, anhydrous triethylamine, and N,N'-dicyclohexylcarbodiimide were added sequentially. The molar ratio of the activated hydroxyphosphate intermediate, 2,2,2-trifluoroethanol, anhydrous triethylamine, and N,N'-dicyclohexylcarbodiimide was 1:1.1:1.5:1.2. The reaction was carried out at 10 °C for 80 min, and then the temperature was raised to 30 °C and stirred for 12 h. After the reaction was completed, the mixture was filtered, and the filtrate was poured into ice water under stirring to precipitate. The precipitated solid was collected by vacuum filtration, and the filter cake was washed sequentially with ice water, dilute hydrochloric acid, and ice water. The product was then dried to obtain the monofluorinated nucleating agent precursor for later use. Step 3: Disperse 8.0g of the monofluorinated nucleating agent precursor obtained in Step 2 in 80ml of tetrahydrofuran aqueous solution (tetrahydrofuran to water volume ratio 3:1). Heat to 60℃, then add dropwise 20ml of aqueous solution containing 0.23g of zinc acetate monohydrate and 0.17g of anhydrous sodium acetate under stirring. After the addition is complete, maintain the reaction at 60℃ for 10h. After the reaction is complete, filter while hot, wash the filter cake with 50℃ deionized water until the washing liquid is neutral, and dry the light yellow solid to obtain HFE-ZnNa nucleating agent.

[0027] Low-viscosity, high-transparency PET composite materials are prepared by the following methods: Step 1: Dry the PET resin and PCTG resin in an oven at 140℃ for 6 hours to obtain the dried PET resin and the dried PCTG resin. Step 2: Add the modified nucleating agent, toughening compatibilizer, lubricant, antioxidant, and the dried PET resin obtained in Step 1 to a high-speed mixer. After thorough mixing, add the mixture to a twin-screw extruder for heating and melting. Then, add the dried PCTG resin obtained in Step 1 to the twin-screw extruder via side feeding. After the molten material is extruded through the die head, it is granulated using water-cooled stringing or underwater pelletizing to obtain a low-viscosity, high-permeability PET composite material.

[0028] Example 2

[0029] This embodiment provides a low-viscosity, high-permeability PET composite material and its preparation method. The low-viscosity, high-permeability PET composite material comprises 100 parts by weight of PET resin, 10 parts by weight of PCTG resin, 0.2 parts by weight of HFE-ZnNa nucleating agent, 5 parts by weight of maleic anhydride-grafted POE with a grafting rate of 0.6%, 0.3 parts by weight of pentaerythritol tetrastearate, and 0.3 parts by weight of antioxidant 1010.

[0030] The HFE-ZnNa nucleating agent is prepared by the following method: Step 1: Add 10g of NA-50 and 150ml of tetrahydrofuran to the reactor and stir to form a suspension. Under the condition of cooling in an ice-water bath, add 80ml of 0.5mol / L hydrochloric acid solution dropwise. The addition is completed in 30min. Then remove the ice-water bath and stir the mixture at 20℃ for 8h. After the reaction is completed, remove the tetrahydrofuran by vacuum distillation to obtain a white solid. Wash with deionized water and dry to obtain the activated hydroxyphosphate intermediate for later use. Step 2: Under a nitrogen atmosphere, 8.5 g of the prepared activated hydroxyphosphate intermediate was dissolved in tetrahydrofuran, and then 2,2,2-trifluoroethanol, anhydrous triethylamine, and N,N'-dicyclohexylcarbodiimide were added sequentially. The molar ratio of the activated hydroxyphosphate intermediate, 2,2,2-trifluoroethanol, anhydrous triethylamine, and N,N'-dicyclohexylcarbodiimide was 1:1.1:1.5:1.2. The reaction was carried out at 0°C for 40 min, and then the temperature was raised to 20°C and stirred for 8 h. After the reaction was completed, the mixture was filtered, and the filtrate was poured into ice water under stirring to precipitate. The precipitated solid was collected by vacuum filtration, and the filter cake was washed sequentially with ice water, dilute hydrochloric acid, and ice water. The product was then dried to obtain the monofluorinated nucleating agent precursor for later use. Step 3: Disperse 8.0g of the monofluorinated nucleating agent precursor obtained in Step 2 in 80ml of tetrahydrofuran aqueous solution (tetrahydrofuran to water volume ratio 3:1). Heat to 40℃, then add dropwise 20ml of aqueous solution containing 0.23g of zinc acetate monohydrate and 0.17g of anhydrous sodium acetate under stirring. After the addition is complete, maintain the reaction at 50℃ for 6h. After the reaction is complete, filter while hot, wash the filter cake with deionized water at 40℃ until the washing liquid is neutral, and dry the light yellow solid to obtain HFE-ZnNa nucleating agent.

[0031] Low-viscosity, high-transparency PET composite materials are prepared by the following methods: Step 1: Dry the PET resin and PCTG resin in an oven at 120℃ for 4 hours to obtain the dried PET resin and the dried PCTG resin. Step 2: Add the modified nucleating agent, toughening compatibilizer, lubricant, antioxidant, and the dried PET resin obtained in Step 1 to a high-speed mixer. After thorough mixing, add the mixture to a twin-screw extruder for heating and melting. Then, add the dried PCTG resin obtained in Step 1 to the twin-screw extruder via side feeding. After the molten material is extruded through the die head, it is granulated using water-cooled stringing or underwater pelletizing to obtain a low-viscosity, high-permeability PET composite material.

[0032] Example 3

[0033] This embodiment provides a low-viscosity, high-permeability PET composite material and its preparation method. The low-viscosity, high-permeability PET composite material comprises 90 parts by weight of PET resin, 15 parts by weight of PCTG resin, 0.4 parts by weight of HFE-ZnNa nucleating agent, 8 parts by weight of maleic anhydride-grafted POE with a grafting rate of 0.8%, 0.4 parts by weight of pentaerythritol tetrastearate, and 0.4 parts by weight of antioxidant 1010.

[0034] The HFE-ZnNa nucleating agent is prepared by the following method: Step 1: Add 10g of NA-50 and 150ml of tetrahydrofuran to the reactor and stir to form a suspension. Under the condition of cooling in an ice-water bath, add 80ml of 0.5mol / L hydrochloric acid solution dropwise. The addition is completed in 30min. Then remove the ice-water bath and stir the mixture at 25℃ for 10h. After the reaction is completed, remove the tetrahydrofuran by vacuum distillation to obtain a white solid. Wash with deionized water and dry to obtain the activated hydroxyphosphate intermediate for later use. Step 2: Under a nitrogen atmosphere, 8.5 g of the prepared activated hydroxyphosphate intermediate was dissolved in tetrahydrofuran, and then 2,2,2-trifluoroethanol, anhydrous triethylamine, and N,N'-dicyclohexylcarbodiimide were added sequentially. The molar ratio of the activated hydroxyphosphate intermediate, 2,2,2-trifluoroethanol, anhydrous triethylamine, and N,N'-dicyclohexylcarbodiimide was 1:1.1:1.5:1.2. The reaction was carried out at 5°C for 60 min, and then the temperature was raised to 25°C and stirred for 10 h. After the reaction was completed, the mixture was filtered, and the filtrate was poured into ice water under stirring to precipitate. The precipitated solid was collected by vacuum filtration, and the filter cake was washed sequentially with ice water, dilute hydrochloric acid, and ice water. The product was then dried to obtain the monofluorinated nucleating agent precursor for later use. Step 3: Disperse 8.0g of the monofluorinated nucleating agent precursor obtained in Step 2 in 80ml of tetrahydrofuran aqueous solution (tetrahydrofuran to water volume ratio 3:1). Heat to 50℃, then add dropwise 20ml of aqueous solution containing 0.23g of zinc acetate monohydrate and 0.17g of anhydrous sodium acetate under stirring. After the addition is complete, maintain the reaction at 55℃ for 8h. After the reaction is complete, filter while hot, wash the filter cake with deionized water at 45℃ until the washing liquid is neutral, and dry the light yellow solid to obtain HFE-ZnNa nucleating agent.

[0035] Low-viscosity, high-transparency PET composite materials are prepared by the following methods: Step 1: Dry the PET resin and PCTG resin in an oven at 130℃ for 5 hours to obtain the dried PET resin and the dried PCTG resin. Step 2: Add the modified nucleating agent, toughening compatibilizer, lubricant, antioxidant, and the dried PET resin obtained in Step 1 to a high-speed mixer. After thorough mixing, add the mixture to a twin-screw extruder for heating and melting. Then, add the dried PCTG resin obtained in Step 1 to the twin-screw extruder via side feeding. After the molten material is extruded through the die head, it is granulated using water-cooled stringing or underwater pelletizing to obtain a low-viscosity, high-permeability PET composite material.

[0036] Comparative Example 1 This comparative example provides a PET composite material and its preparation method. The low-viscosity, high-permeability PET composite material comprises 90 parts by weight of PET resin, 15 parts by weight of PCTG resin, 8 parts by weight of maleic anhydride-grafted POE with a grafting rate of 0.8%, 0.4 parts by weight of pentaerythritol tetrastearate, and 0.4 parts by weight of antioxidant 1010.

[0037] PET composite materials are prepared by the following methods: Step 1: Dry the PET resin and PCTG resin in an oven at 130℃ for 5 hours to obtain the dried PET resin and the dried PCTG resin. Step 2: Add the toughening compatibilizer, lubricant, antioxidant, and the dried PET resin obtained in Step 1 to a high-speed mixer. After thorough mixing, add the mixture to a twin-screw extruder for heating and melting. Then, add the dried PCTG resin obtained in Step 1 to the twin-screw extruder via side feeding. After the molten material is extruded through the die head, it is granulated using water-cooled stringing or underwater pelletizing to obtain the PET composite material.

[0038] Comparative Example 2 This comparative example provides a PET composite material and its preparation method. The low-viscosity, high-permeability PET composite material comprises 90 parts by weight of PET resin, 15 parts by weight of PCTG resin, 0.4 parts by weight of NA-50 nucleating agent, 8 parts by weight of maleic anhydride-grafted POE with a grafting rate of 0.8%, 0.4 parts by weight of pentaerythritol tetrastearate, and 0.4 parts by weight of antioxidant 1010.

[0039] PET composite materials are prepared by the following methods: Step 1: Dry the PET resin and PCTG resin in an oven at 130℃ for 5 hours to obtain the dried PET resin and the dried PCTG resin. Step 2: Add NA-50 nucleating agent, toughening compatibilizer, lubricant, antioxidant, and the dried PET resin obtained in Step 1 to a high-speed mixer. After thorough mixing, add the mixture to a twin-screw extruder for heating and melting. Then, add the dried PCTG resin obtained in Step 1 to the twin-screw extruder via side feeding. After the molten material is extruded through the die head, it is granulated using water-cooled stringing or underwater pelletizing to obtain the PET composite material.

[0040] Application Example 1 GB / T 14190-2017 measured the viscosity and color values ​​of the PET composite materials prepared in Example 3, Comparative Example 1, and Comparative Example 2, respectively. Viscosity was measured using the method described in GB / T 17931-2018 "Polyethylene terephthalate (PET) resin for bottles," and color values ​​were measured using the method described in GB / T 14190-2017 "Test methods for fiber-grade polyester (PET) chips." The results are shown in the table below:

[0041] Results Analysis: Comparison of the above experimental results shows that the HFE-ZnNa nucleating agent provided by this invention has better performance than the traditional NA-50 nucleating agent, and the resulting composite material has the characteristics of high permeability and low viscosity, thus achieving the invention objective.

[0042] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A low-viscosity, high-permeability PET composite material, characterized in that: It includes 80-100 parts by weight of PET resin, 10-20 parts of PCTG resin, 0.2-0.6 parts of modified nucleating agent, 5-10 parts of toughening compatibilizer, 0.3-0.5 parts of lubricant and 0.3-0.5 parts of antioxidant.

2. The low-viscosity, high-permeability PET composite material as described in claim 1, characterized in that: The modified nucleating agent is an HFE-ZnNa nucleating agent, which is prepared by the following method: Step 1: Add NA-50 and tetrahydrofuran to the reactor and stir to form a suspension. Under the condition of cooling in an ice-water bath, add hydrochloric acid solution dropwise. After the addition is complete, remove the ice-water bath and stir the mixture at 20-30℃ for 8-12 hours. After the reaction is complete, remove the tetrahydrofuran by vacuum distillation to obtain a white solid. Wash with deionized water and dry to obtain the activated hydroxyphosphate intermediate for later use. Step 2: Under a nitrogen atmosphere, the prepared activated hydroxyphosphate intermediate is dissolved in tetrahydrofuran, and then 2,2,2-trifluoroethanol, anhydrous triethylamine and N,N'-dicyclohexylcarbodiimide are added sequentially. The reaction is carried out at 0-10℃ for 40-80 min, and then the temperature is raised to 20-30℃ and stirred for 8-12 h. After the reaction is completed, the mixture is filtered, and the filtrate is poured into ice water under stirring to precipitate. The precipitated solid is collected by vacuum filtration, and the filter cake is washed sequentially with ice water, dilute hydrochloric acid and ice water. The product is then dried to obtain the monofluorinated nucleating agent precursor for later use. Step 3: Disperse the monofluorinated nucleating agent precursor obtained in Step 2 in an aqueous solution of tetrahydrofuran, heat to 40-60℃, and then add an aqueous solution of zinc acetate monohydrate and anhydrous sodium acetate dropwise under stirring. After the addition is complete, maintain the reaction at 50-60℃ for 6-10 hours. After the reaction is complete, filter while hot, wash the filter cake with deionized water at 40-50℃ until the washing liquid is neutral, and dry the light yellow solid to obtain the HFE-ZnNa nucleating agent.

3. The low-viscosity, high-permeability PET composite material as described in claim 2, characterized in that: In step one, the hydrochloric acid solution is 0.5 mol / L, and the addition time is 30 min.

4. The low-viscosity, high-permeability PET composite material as described in claim 2, characterized in that: The molar ratio of the activated hydroxyphosphate intermediate, 2,2,2-trifluoroethanol, anhydrous triethylamine, and N,N'-dicyclohexylcarbodiimide added in step two is 1:1.1:1.5:1.

2.

5. The low-viscosity, high-permeability PET composite material as described in claim 2, characterized in that: The molar ratio of zinc acetate monohydrate and anhydrous sodium acetate added in step three is 1:

2.

6. The low-viscosity, high-permeability PET composite material as described in claim 1, characterized in that: The toughening compatibilizer is maleic anhydride-grafted POE.

7. The low-viscosity, high-permeability PET composite material as described in claim 6, characterized in that: The grafting rate of maleic anhydride-grafted POE is 0.6%-1.0%.

8. The low-viscosity, high-permeability PET composite material as described in claim 1, characterized in that: The lubricant is pentaerythritol tetrastearate.

9. The low-viscosity, high-permeability PET composite material as described in claim 1, characterized in that: The antioxidant is antioxidant 1010.

10. A method for preparing a low-viscosity, high-permeability PET composite material as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Dry the PET resin and PCTG resin in an oven at 120-140℃ for 4-6 hours to obtain dried PET resin and dried PCTG resin. Step 2: Add the modified nucleating agent, toughening compatibilizer, lubricant, antioxidant, and the dried PET resin obtained in Step 1 to a high-speed mixer. After thorough mixing, add the mixture to a twin-screw extruder for heating and melting. Then, add the dried PCTG resin obtained in Step 1 to the twin-screw extruder via side feeding. After the molten material is extruded through the die head, it is granulated using water-cooled stringing or underwater pelletizing to obtain a low-viscosity, high-permeability PET composite material.

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