Modified PET (Polyethylene Terephthalate) material and application thereof in preparation of catering supplies

Abstract

The invention discloses a modified PET material and application thereof in preparation of catering supplies, the modified PET material comprises the following raw materials by mass: 80-90% of PET, 10-20% of a PPS-boron nitride conjugate, and 0.3-0.5% of an antioxidant; the PPS-boron nitride conjugate is prepared by the following method: (1) introducing an azide group on boron nitride to obtain BN-N3; (2) introducing alkynyl on a benzene ring of PPS to obtain PPS-C = CH; and (3) carrying out a click chemical reaction on BN-N3 and PPS-C = CH under the catalysis of copper ions, so as to obtain the PPS-boron nitride conjugate. According to the invention, the PPS-boron nitride conjugate is adopted to modify PET, and the conjugate is beneficial to improving the crystallization capacity of PET, accelerating the crystallization rate of PET and improving the heat conduction efficiency of the PET material, so that the modified PET material is easier to process and form.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a modified PET material and its application in the preparation of catering utensils. Background Art

[0002] In recent years, with the continuous improvement of environmental protection laws in various countries, people's attention to health has been increasing. Due to the characteristics of melamine materials such as releasing melamine after contacting high temperatures, insufficient toughness and being prone to cracking when dropped, being prone to discoloration after long-term use, not being able to enter the microwave oven, and being non-recyclable, more and more users have criticized them. Therefore, the GB 4806 national standard implemented in China in September 2024 clearly prohibits the production and sale of melamine tableware containing plant fibers. Melamine materials have gradually become a material that urgently needs to be replaced.

[0003] There are rigid groups in the molecular main chain of polyethylene terephthalate (abbreviation: PET), so it has high heat resistance, and its use temperature can reach above 120 °C. Coupled with its strong chemical stability, it has great application potential in the tableware market; however, PET materials also have defects such as slow crystallization rate, difficult forming and processing, and low impact strength, and need to be modified.

[0004] For example, the Chinese invention patent application with the publication number of CN116731485A discloses a polyethylene terephthalate modified material that can be resistant to high-temperature yellowing for a long time. The raw material composition of this PET modified material is: 100 parts of PET, 10 - 50 parts of filled mineral powder, 1 - 20 parts of reinforcing fiber, 0.5 - 2 parts of antioxidant, 0.5 - 2 parts of nucleating agent, and 0.5 - 2 parts of lubricant.

[0005] Although filled mineral powder and reinforcing fiber can improve the mechanical properties of PET to a certain extent, there is a non-negligible poor interfacial bonding between these inorganic materials and PET, resulting in the modification not achieving the expected effect. Summary of the Invention

[0006] The invention purpose of the present invention is to provide a modified PET material and its application in the preparation of catering utensils. This modified PET material has a fast crystallization rate, is easy to form, and has a lower processing temperature.

[0007] To achieve the above invention purpose, the technical solution of the present invention is as follows: A modified PET material, calculated by mass percentage, this modified PET material includes the following raw materials: 80 - 90% of PET, 10 - 20% of PPS-boron nitride conjugate, and 0.3 - 0.5% of antioxidant; The described PPS-boron nitride conjugate is prepared by the following method: (1) Introduce azide groups onto boron nitride to obtain BN-N3; (2) Introduce an alkynyl group onto the benzene ring of PPS to obtain PPS-C≡CH; (3) Under the catalysis of cuprous ions, carry out a click chemical reaction between BN-N3 and PPS-C≡CH to obtain the PPS-boron nitride conjugate.

[0008] In the present invention, PET is modified with the PPS-boron nitride conjugate. The PPS-boron nitride conjugate is formed by coupling boron nitride and PPS through a click chemical reaction between azide and alkynyl groups. This conjugate has a nucleating effect on PET. Among them, the boron nitride part in the conjugate can not only serve as the nucleation center of PET but also construct a heat conduction path, increasing the thermal diffusivity of the material by more than 40%; while the PPS part can not only promote the uniform dispersion of the conjugate in PET, effectively improving the nucleation efficiency, but also reduce the melt viscosity of the system, lowering the processing temperature of the system from 340 °C to 310 °C; therefore, the PPS-boron nitride conjugate is beneficial to improving the crystallization ability of PET, accelerating the PET crystallization rate, beneficial to improving the heat conduction efficiency of PET materials, and making the modified PET materials easier to process and form.

[0009] In addition, both boron nitride and PPS have excellent thermal stability, wear resistance, and chemical stability, which also endow the modified PET materials with corresponding properties.

[0010] Preferably, the above step (1) includes: 1) Place boron nitride powder in a strong acid solution for reflux oxidation to obtain BN-OH; 2) React BN-OH with a sulfonylation reagent in a solvent to obtain BN-OTs; 3) React BN-OTs with an azidation reagent in a solvent to obtain BN-N3.

[0011] More preferably, in the above step 1), the strong acid solution is composed of concentrated sulfuric acid and concentrated nitric acid mixed at a volume ratio of (2 - 4):1, and the mass-volume ratio of boron nitride powder to the strong acid solution is 1 g:(30 - 40) mL; The reflux oxidation temperature is 100 - 120 °C, and the reflux oxidation time is 6 - 12 h.

[0012] More preferably, in the above step 2), the sulfonylation reagent includes p-toluenesulfonyl chloride, and the equivalent ratio of BN-OH to the sulfonylation reagent is 1:(1.0 - 1.2); The solvent is pyridine, the reaction temperature is room temperature, and the reaction time is 2 - 6 h.

[0013] More preferably, in the above step 3), the azidation reagent includes sodium azide, and the equivalent ratio of BN-OTs to the azidation reagent is 1:(1.2 - 2.0); The solvent described is dimethylformamide, the reaction temperature is room temperature or 60 - 80 °C, and the reaction time is 4 - 24 h.

[0014] Among them, when reacting at room temperature, the reaction time is longer (12 - 24 h); when reacting at 60 - 80 °C, the reaction time is shorter (4 - 8 h).

[0015] Preferably, the above step (2) includes: a) Under the protection of an inert atmosphere, reacting PPS with a brominating reagent in a solvent to obtain brominated PPS; b) Under the protection of an inert atmosphere and in the presence of a palladium / copper catalyst, carrying out a Sonogashira coupling reaction between brominated PPS and a terminal alkyne in a solvent to obtain PPS-C≡CH.

[0016] Preferably, the average molecular weight of PPS used in the present invention is between 4000 - 5000 Da, and the average molecular weight of PET is 30000 - 40000 Da.

[0017] More preferably, in the above step a), PPS is first dispersed in anhydrous chloroform, then a radical initiator is added under the protection of an inert atmosphere, heated to 65 - 70 °C, and then N-bromosuccinimide is added, and stirred for reaction for 8 - 10 h; the molar ratio of PPS, radical initiator and N-bromosuccinimide is 1:(0.01 - 0.05):(0.8 - 1.5); In step b), under the protection of an inert atmosphere, brominated PPS, palladium / copper catalyst, ligand and solvent are first mixed, then a base and a terminal alkyne are added, and reacted at room temperature or heated to 60 - 80 °C for 12 - 24 h; The dosage of the terminal alkyne is 1.2 - 2 equivalents / 1 equivalent of bromine, and the dosage of the base is 2 - 5 equivalents / 1 equivalent of bromine.

[0018] Preferably, in the above step (3), BN-N3 and PPS-C≡CH are first dissolved in a solvent according to the equivalent ratio of azide / alkyne group of (1.0 - 1.2):1.0, then a ligand and a copper catalyst are added, stirred in the dark for 10 - 15 min, and then reacted in the dark at room temperature or heated to 40 - 60 °C for 6 - 24 h under the protection of an inert atmosphere.

[0019] The present invention also provides a preparation method of the above modified PET material, and the preparation method includes: first mixing PET and an antioxidant according to a preset mass percentage to obtain a premix; then mixing the premix and a PPS-boron nitride conjugate according to a preset mass percentage, and finally melt-extruding.

[0020] The present invention also provides the application of the above-mentioned modified PET material in the preparation of food and beverage utensils. The food and beverage utensils made of the modified PET material not only have the characteristics of easy molding, good hand feeling, high temperature resistance, wear resistance, drop resistance, steam resistance, no deformation, no color change, no cracking, recyclability, easy cleaning, etc., but also can be safely used in a microwave oven, and also exhibit extremely strong acid and alkali resistance.

[0021] The food and beverage utensils referred to in the present invention include but are not limited to: food packaging containers (such as food storage boxes, beverage bottles or cans, seasoning bottles, etc.), food processing utensils (such as food production molds, mixer accessories for food processing, food conveying pipelines or conveyor belts, etc.), tableware (such as dinner plates, bowls, spoons, chopsticks, etc.), takeout packaging (such as takeout food boxes, takeout bags, etc.).

[0022] Compared with the prior art, the technical effects of the present invention are reflected in: (1) In the present invention, PET is modified with a PPS-boron nitride conjugate. The PPS-boron nitride conjugate is formed by coupling boron nitride and PPS through a click chemical reaction between azide and alkyne groups. The conjugate has a nucleating effect on PET. Among them, the boron nitride part in the conjugate can not only serve as a nucleating center for PET, but also build a heat conduction path, increasing the thermal diffusivity of the material by more than 40%; while the PPS part can not only promote the uniform dispersion of the conjugate in PET, effectively improving the nucleation efficiency, but also reducing the melt viscosity of the system, reducing the processing temperature of the system from 340 °C to 310 °C; therefore, the PPS-boron nitride conjugate is beneficial to improving the crystallization ability of PET, accelerating the PET crystallization rate, and is beneficial to improving the heat conduction efficiency of the PET material, making the modified PET material easier to process and form.

[0023] (2) In the present invention, both boron nitride and PPS have excellent thermal stability, wear resistance and chemical stability, which also endow the modified PET material with corresponding properties.

[0024] (3) The food and beverage utensils made of the modified PET material of the present invention not only have the characteristics of easy molding, good hand feeling, high temperature resistance, wear resistance, drop resistance, steam resistance, no deformation, no color change, no cracking, recyclability, easy cleaning, etc., but also can be safely used in a microwave oven, and also exhibit extremely strong acid and alkali resistance. Specific Embodiments

[0025] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments.

[0026] Example 1 A modified PET material in this example, by mass percentage, the modified PET material includes the following raw materials: 90% PET, 9.7% PPS-boron nitride conjugate, 0.3% antioxidant; Among them, the molecular weight of PET is 34,000 Da, and the antioxidant is antioxidant 1098; The PPS-boron nitride conjugate is prepared by the following method: (1) Introduce an azide group onto boron nitride to obtain BN-N3; Step (1) further includes: 1) Place boron nitride powder in a strong acid solution and reflux for oxidation to obtain BN-OH; Specifically, first take boron nitride powder with a particle size of 5 μm, and mix 98% concentrated sulfuric acid and 65% concentrated nitric acid in a volume ratio of 2:1 to obtain a strong acid solution; then mix the boron nitride powder and the strong acid solution at a mass-volume ratio of 1 g:40 mL, ultrasonically disperse for 20 min, reflux and oxidize at 100 °C for 12 h; then slowly pour 10 times the volume of ice water into the reaction solution to cool and dilute, and adjust the pH to neutral with an alkali solution; centrifuge at 10,000 rpm for 15 min and then filter, collect the precipitate, wash it repeatedly with deionized water until neutral, and then wash it with acetone; finally, dry it under vacuum to obtain BN-OH; 2) React BN-OH with a sulfonylation reagent in a solvent to obtain BN-OTs; Specifically, first dissolve BN-OH (1 equivalent) in anhydrous pyridine (2 equivalents) in a dry reaction flask, add a catalyst DMAP (0.1 equivalent), and cool to 0 °C in an ice bath; then slowly dropwise add anhydrous p-toluenesulfonyl chloride (1 equivalent), keeping the temperature at 0 °C; after the addition is complete, remove the ice bath, gradually warm to room temperature, and continue stirring and reacting for 2 h; after the reaction is completed, slowly pour the reactant into ice water to quench, then extract the organic phase with ethyl acetate, wash it with saturated sodium bicarbonate solution, and dry it with anhydrous sodium sulfate; then concentrate the organic phase under reduced pressure and purify it by column chromatography to obtain BN-OTs; 3) React BN-OTs with an azidating reagent in a solvent to obtain BN-N3; Specifically, under the protection of an inert atmosphere (nitrogen), dissolve BN-OTs (1 equivalent) in 5 mL of anhydrous dimethylformamide, continue to add sodium azide (1.5 equivalents), and stir until completely dissolved; then slowly heat to 60 °C and react for 8 h; after the reaction is completed, pour the reaction solution into ice water to quench; then extract with dichloromethane, wash, dry with anhydrous sodium sulfate, concentrate under reduced pressure to remove the solvent, and finally purify and dry to obtain BN-N3; (2) Introduce an alkynyl group onto the benzene ring of PPS to obtain PPS-C≡CH; Step (2) further includes: a) Under the protection of an inert atmosphere and catalyzed by a Lewis acid, react PPS with a brominating reagent in a solvent to obtain brominated PPS; Specifically, add PPS powder (10 g, Fortron 1140L6) into a dry three-necked flask, add 150 mL of chloroform, and stir to disperse PPS; pass nitrogen for 15 min to remove air; add a radical initiator (AIBN, 0.3 g), heat to 65 °C, and then add 12 g of N-bromosuccinimide in three portions at intervals of 30 min each; maintain the nitrogen atmosphere and continue stirring and reacting for 8 h; after the reaction solution gradually turns from colorless to light yellow, cool to room temperature, and add 50 mL of 10% sodium sulfite solution, stir for 30 min to quench the reaction; filter to collect the solid product, and after washing and vacuum drying, obtain brominated PPS (as determined, the bromination positions are basically all on the benzene ring, and the bromine content is 20%); b) Under the protection of an inert atmosphere and in the presence of a palladium / copper catalyst, carry out a Sonogashira coupling reaction between brominated PPS and a terminal alkyne in a solvent to obtain PPS-C≡CH; Specifically, first add 1.0 g of brominated PPS, 0.02 mol of Pd(PPh3)2Cl2, 0.04 mol of CuI, and 0.04 mol of PPh3 into a Schlenk tube, and then evacuate and refill with nitrogen three times to ensure an oxygen-free environment; add 20 mL of anhydrous DMF, stir until the brominated PPS is basically dissolved (it can be heated to 60 °C to promote the dissolution of brominated PPS); then successively add 1.2 equivalents / 1 equivalent of bromine of trimethylsilylacetylene and 3 equivalents / 1 equivalent of bromine of triethylamine, raise the temperature to 80 °C, and reflux and react for 24 h; after the reaction is completed, cool to room temperature, add 10 mL of methanol to quench, and then drop the reaction solution into 200 mL of methanol / water (9:1) to precipitate the polymer; after filtration, washing, and drying, obtain PPS-C≡C-TMS; further treat with 1M TBAF (dissolved in THF) for deprotection to obtain PPS-C≡CH; (3) Under the catalysis of copper ions, carry out a click chemical reaction between BN-N3 and PPS-C≡CH to obtain the PPS-boron nitride conjugate of this example; Specifically, under the protection of an inert atmosphere, first dissolve BN-N3 (0.16 g, containing 1.2 mmol of azide groups) and PPS-C≡CH (1.0 g, containing 1.0 mmol of alkyne groups) in 15 mL of deoxygenated DMF (ultrasonic assistance for dissolution is necessary if needed), then add a ligand (TBTA, 0.01 g) and a copper catalyst (CuBr(PPh3)3, 0.02 g), stir in the dark for 10 min, and then heat to 50 °C and react in the dark for 12 h; add an aqueous solution of EDTA to quench, and drop the reaction solution into 200 mL of methanol / water (9:1) to precipitate the polymer; after filtration, washing, and drying, obtain the PPS-boron nitride conjugate.

[0027] The preparation method of the modified PET material includes: first, mixing PET and an antioxidant in a twin-screw granulator according to a preset mass percentage to obtain a premix; then mixing the premix and a PPS-boron nitride conjugate according to a preset mass percentage, and finally melt-extruding, granulating or cutting.

[0028] Example 2 In this example, a modified PET material, by mass percentage, the modified PET material includes the following raw materials: 80% PET, 19.5% PPS-boron nitride conjugate, 0.5% antioxidant; Among them, the molecular weight of PET is 34000 Da, and the antioxidant is antioxidant 1098; The PPS-boron nitride conjugate is prepared by the following method: (1) Introducing an azide group onto boron nitride to obtain BN-N3; Step (1) further includes: 1) Placing boron nitride powder in a strong acid solution for reflux oxidation to obtain BN-OH; Specifically, first take boron nitride powder with a particle size of 5 μm, and mix 98% concentrated sulfuric acid and 65% concentrated nitric acid in a volume ratio of 3:1 to obtain a strong acid solution; then mix the boron nitride powder and the strong acid solution in a mass-volume ratio of 1 g:30 mL, ultrasonically disperse for 20 min, and reflux oxidize at 120 °C for 8 h; then slowly pour 10 times the volume of ice water into the reaction solution to cool and dilute, and adjust the pH to neutral with an alkali solution; centrifuge at 10000 rpm for 15 min and then filter, collect the precipitate, wash it repeatedly with deionized water until neutral, and then wash it with acetone; finally, dry it under vacuum to obtain BN-OH; 2) Reacting BN-OH with a sulfonylation reagent in a solvent to obtain BN-OTs; Specifically, first dissolve BN-OH (1 equivalent) in anhydrous pyridine (2 equivalents) in a dry reaction flask, add a catalyst DMAP (0.1 equivalent), and cool it to 0 °C in an ice bath; then slowly dropwise add anhydrous p-toluenesulfonyl chloride (1.2 equivalents), keeping the temperature at 0 °C; after dropping, remove the ice bath, gradually warm up to room temperature, and continue stirring and reacting for 2 h; after the reaction is completed, slowly pour the reactant into ice water to quench, then extract the organic phase with ethyl acetate, wash it with saturated sodium bicarbonate solution, and dry it with anhydrous sodium sulfate; then concentrate the organic phase under reduced pressure and purify it by column chromatography to obtain BN-OTs; 3) Reacting BN-OTs with an azidating reagent in a solvent to obtain BN-N3; Specifically, under the protection of an inert atmosphere (nitrogen), BN-OTs (1 equivalent) was dissolved in 5 mL of anhydrous dimethylformamide, and then sodium azide (1.2 equivalents) was added and stirred until completely dissolved; then, it was slowly heated to 80 °C and reacted for 4 h; after the reaction was completed, the reaction solution was poured into ice water for quenching; then, it was extracted with dichloromethane, washed, dried over anhydrous sodium sulfate, concentrated under reduced pressure to remove the solvent, and finally purified and dried to obtain BN-N3; (2) Introduce an alkynyl group onto the benzene ring of PPS to obtain PPS-C≡CH; Step (2) further includes: a) Under the protection of an inert atmosphere, react PPS with a brominating reagent in a solvent to obtain brominated PPS; Specifically, add PPS powder (10 g, Fortron 1140L6) to a dry three-necked flask, add 150 mL of chloroform, and stir to disperse PPS; pass nitrogen for 15 min to remove air; add a radical initiator (AIBN, 0.2 g), heat to 70 °C, and then add 10 g of N-bromosuccinimide in three portions at 30-min intervals; maintain the nitrogen atmosphere and continue to stir and react for 10 h; after the reaction solution gradually turns from colorless to light yellow, cool to room temperature, and add 50 mL of 10% sodium sulfite solution and stir for 30 min to quench the reaction; filter to collect the solid product, wash and dry in vacuo to obtain brominated PPS (as determined, the bromination position is basically on the benzene ring and the bromine content is 20%); b) Under the protection of an inert atmosphere and a palladium / copper catalyst, carry out a Sonogashira coupling reaction between brominated PPS and a terminal alkyne in a solvent to obtain PPS-C≡CH; Specifically, first add 1.0 g of brominated PPS, 0.02 mol of Pd(PPh3)2Cl2, 0.04 mol of CuI, and 0.04 mol of PPh3 to a Schlenk tube, and then evacuate and fill with nitrogen three times to ensure an oxygen-free environment; add 20 mL of anhydrous DMF and stir until brominated PPS is basically dissolved (it can be heated to 60 °C to promote the dissolution of brominated PPS); then add 2 equivalents / 1 equivalent of bromine of trimethylsilylacetylene and 4 equivalents / 1 equivalent of bromine of triethylamine in sequence, raise the temperature to 80 °C, and reflux and react for 24 h; after the reaction is completed, cool to room temperature, add 10 mL of methanol for quenching, and then drop the reaction solution into 200 mL of methanol / water (9:1) to precipitate the polymer; after filtration, washing, and drying, obtain PPS-C≡C-TMS; further treat with 1M TBAF (dissolved in THF) for deprotection to obtain PPS-C≡CH; (3) Under the catalysis of copper ions, carry out a click chemical reaction between BN-N3 and PPS-C≡CH to obtain the PPS-boron nitride conjugate of this example; Specifically, under the protection of an inert atmosphere, first dissolve BN-N3 (0.16 g, containing 1.2 mmol of azide groups) and PPS-C≡CH (1.0 g, containing 1.0 mmol of alkynyl groups) in 15 mL of deoxygenated DMF (ultrasonic assistance for dissolution if necessary), then add the ligand (TBTA, 0.01 g) and the copper catalyst (CuBr(PPh3)3, 0.02 g). After stirring in the dark for 10 min, heat to 50 °C and react in the dark for 12 h; quench with an aqueous EDTA solution, and drop the reaction solution into 200 mL of methanol / water (9:1) to precipitate the polymer; after filtration, washing, and drying, obtain the PPS-boron nitride conjugate.

[0029] The preparation method of the modified PET material includes: first mixing PET and an antioxidant in a twin-screw granulator according to a preset mass percentage to obtain a premix; then mixing the premix and the PPS-boron nitride conjugate according to a preset mass percentage, and finally melt-extruding, granulating or cutting.

[0030] Comparative Example 1 A modified PET material in this comparative example, by mass percentage, includes the following raw materials: 80% PET, 15% PPS (Fortron 1140L6), 3% boron nitride (particle size 5 μm), 1.5% titanate coupling agent (KR-38S), and 0.5% antioxidant 1098.

[0031] The preparation method of the modified PET material includes: mixing all raw materials in a twin-screw granulator according to a preset mass percentage, then melt-extruding, granulating or cutting.

[0032] Take the modified PET materials prepared in Examples 1-2 and Comparative Example 1, and test the various properties of each material. The results are shown in Table 1.

[0033] Table 1 Performance tests of each modified PET material Test Items Standard Method Example 1 Example 2 Comparative Example 1 Heat Deflection Temperature (HDT) ISO 75-2 343℃ 357℃ 265℃ Wear Rate ASTM G99 0.02 mm³ / N·m 0.01mm³ / N·m 0.04 mm³ / N·m Thermal Conductivity ASTM D5470 3.6 W / (m·K) 4.5W / (m·K) 3.2 W / (m·K) Tensile Strength ISO 527-2 146MPa 195MPa 132 MPa Lead Migration Amount GB 31604.9 0.002mg / kg 0.001mg / kg 0.002 mg / kg Thermal Diffusivity (mm² / s ) ASTM E1952 0.14 0.16 0.12 Crystallization Rate Constant ISO 16725 3.43 4.47 1.20 Crystallization Peak Temperature (Tc,℃) ISO 11357-3 135-145 145-155 125-135℃ Cold Crystallinity (Xc,%) ISO 11357-7 15-20 10-15 25-30 ΔTHc (J / g) ISO 11357 20-25 15-20 30-35 Full Width at Half Maximum (ΔT,℃) ISO 11357 5-8 5-7 8-12 t1 / 2(min,120℃) ISO 14889 2-3 1-2 3-5 K(min⁻ⁿ) ISO 17742 0.03 0.05 0.02 Avramin Index (n) ISO 11357 3 3 2.5 As can be seen from Table 1, compared with directly physically blending PPS and boron nitride with PET, the modified material obtained by first coupling PPS and boron nitride and then mixing it into PET has higher heat distortion temperature, thermal conductivity, tensile strength, thermal diffusivity, and lower wear rate, indicating that the modified PET material of the present invention has high temperature resistance, wear resistance, high strength, high heat conduction efficiency, and strong heat storage capacity; the made food utensils can not only be washed by a dishwasher for a long time, but also facilitate the rapid heating and insulation of the contained food.

[0034] Each crystallization parameter indicates that, since the PPS and boron nitride are coupled in the present invention, it is beneficial to improve the crystallization ability of PET, accelerate the PET crystallization rate, and make the modified PET material of the present invention easier to process and form.

Claims

1. A modified PET material, characterized in that, By mass percentage, it includes the following raw materials: 80 - 90% of PET, 10 - 20% of PPS-boron nitride conjugate, and 0.3 - 0.5% of antioxidant; The described PPS-boron nitride conjugate is prepared by the following method: (1) Introduce an azide group onto boron nitride to obtain BN-N3; (2) Introduce an alkynyl group onto the benzene ring of PPS to obtain PPS-C≡CH; (3) Under the catalysis of copper ions, carry out a click chemical reaction between BN-N3 and PPS-C≡CH to obtain the described PPS-boron nitride conjugate.

2. The modified PET material according to claim 1, characterized in that, Step (1) includes: 1) Place boron nitride powder in a strong acid solution for reflux oxidation to obtain BN-OH; 2) React BN-OH with a sulfonylation reagent in a solvent to obtain BN-OTs; 3) React BN-OTs with an azidation reagent in a solvent to obtain BN-N3.

3. The modified PET material according to claim 2, wherein In step 1), the strong acid solution is composed of concentrated sulfuric acid and concentrated nitric acid mixed at a volume ratio of (2 - 4):1, and the mass-volume ratio of boron nitride powder to the strong acid solution is 1 g:(30 - 40) mL; The reflux oxidation temperature is 100 - 120 °C, and the reflux oxidation time is 6 - 12 h.

4. The modified PET material according to claim 2, wherein In step 2), the sulfonylation reagent includes p-toluenesulfonyl chloride, and the equivalent ratio of BN-OH to the sulfonylation reagent is 1:(1.0 - 1.2); The solvent is pyridine, the reaction temperature is room temperature, and the reaction time is 2 - 6 h.

5. The modified PET material according to claim 2, wherein In step 3), the azidation reagent includes sodium azide, and the equivalent ratio of BN-OTs to the azidation reagent is 1:(1.2 - 2.0); The solvent is dimethylformamide, the reaction temperature is room temperature or 60 - 80 °C, and the reaction time is 4 - 24 h.

6. The modified PET material according to claim 1, characterized in that, Step (2) includes: a) Under the protection of an inert atmosphere, react PPS with a bromination reagent in a solvent to obtain brominated PPS; b) Under the protection of an inert atmosphere and in the presence of a palladium / copper catalyst, carry out a Sonogashira coupling reaction between brominated PPS and a terminal alkyne in a solvent to obtain PPS-C≡CH.

7. The modified PET material according to claim 6, characterized in that, In step a), first disperse PPS in anhydrous chloroform, then add a radical initiator under the protection of an inert atmosphere, heat to 65 - 70 °C, and then add N-bromosuccinimide and stir for reaction for 8 - 10 h; the molar ratio of PPS, radical initiator, and N-bromosuccinimide is 1:(0.01 - 0.05):(0.8 - 1.5); In step b), under the protection of an inert atmosphere, first mix brominated PPS, palladium / copper catalyst, ligand, and solvent, and then add a base and a terminal alkyne, and react at room temperature or heat to 60 - 80 °C for 12 - 24 h; The dosage of the terminal alkyne is 1.2 - 2 equivalents / 1 equivalent of bromine, and the dosage of the base is 2 - 5 equivalents / 1 equivalent of bromine.

8. The modified PET material according to claim 6, characterized in that, In step (3), first dissolve BN-N3 and PPS-C≡CH in a solvent at an equivalent ratio of azide group / alkynyl group of (1.0 - 1.2):1.0, then add a ligand and a copper catalyst, stir in the dark for 10 - 15 min, and then react in the dark at room temperature or heat to 40 - 60 °C under the protection of an inert atmosphere for 6 - 24 h.

9. The preparation method of the modified PET material according to any one of claims 1-8, characterized in that, It includes: First, PET and an antioxidant are mixed evenly according to a preset mass percentage to obtain a premix; Then, the premix and a PPS-boron nitride conjugate are mixed evenly according to a preset mass percentage, and finally melt extrusion is carried out.

10. Use of the modified PET material according to any one of claims 1-8 in the preparation of food and beverage utensils.