A process for preparing PET polyester biodegradable plastic sheets

Abstract

This invention relates to the field of biodegradable plastics technology, and more particularly to a process for preparing PET polyester biodegradable plastic sheets. The raw materials for the aforementioned PET polyester biodegradable plastic sheets, by weight, include: 80-140 parts PET resin, 10-30 parts PBAT resin, 5-15 parts polylactic acid, 5-15 parts degradation aid, 10-30 parts inorganic filler, 1-3 parts graphene oxide, 1-2 parts zinc nitrate, 0.1-1 parts 2-methylimidazole, 1-3 parts antioxidant, 10-20 parts flame retardant, 1-3 parts stabilizer, and 1-2 parts lubricant. This invention can significantly improve the flame retardant and anti-dripping effects of PET materials while maintaining good mechanical properties, and also exhibits significant biodegradability, thus possessing broad market and social benefits.

Description

Technical Field

[0001] This invention relates to the field of biodegradable plastics technology, and in particular to a PET polyester biodegradable plastic sheet and its preparation process. Background Technology

[0002] Polymer materials, as a crucial material foundation of modern industry and daily life, have propelled social development while simultaneously triggering a severe environmental crisis. Currently, polyethylene terephthalate (PET) is widely used due to its excellent mechanical strength, heat resistance, and processing properties. However, PET is difficult to degrade, taking hundreds of years to decompose in the natural environment. The millions of tons of PET waste generated globally each year have created a shocking "white pollution." Traditional landfill disposal results in land resource occupation and groundwater pollution, while incineration releases persistent pollutants such as dioxins.

[0003] Driven by the concept of sustainable development, biodegradable polymer materials have become a research focus. Although materials such as polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) possess microbial degradation properties, PLA's low melting point (approximately 180°C) limits its high-temperature applications, while PBAT's insufficient mechanical strength makes it difficult to meet packaging requirements. Although mechanical strength can be improved through blending modification, this often leads to increased crystallinity, which slows down the degradation rate. Conversely, improving degradation activity sacrifices material usability, making it difficult for existing biodegradable materials to balance environmental benefits and product lifespan requirements in practical applications.

[0004] It is worth noting that traditional PET materials pose significant safety hazards. When burned, they not only produce large amounts of asphyxiating gases such as CO and CO2, but also release energetic particles due to the rapid breakdown of molecular chains, triggering molten dripping. This chain reaction of "combustion-dripping-secondary ignition" greatly exacerbates the fire hazard. Especially in applications such as electronics, building decoration, and other fields, the safety risks of these materials have become a key obstacle restricting their industrial upgrading.

[0005] Therefore, improving the flame retardant properties of PET materials while also maintaining degradability and mechanical properties has excellent research prospects. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by proposing a process for preparing PET polyester biodegradable plastic sheets.

[0007] A biodegradable PET polyester plastic sheet, the raw materials of which include, by weight: 80-140 parts PET resin, 10-30 parts PBAT resin, 5-15 parts polylactic acid, 5-15 parts degradation aid, 10-30 parts inorganic filler, 1-3 parts graphene oxide, 1-2 parts zinc nitrate, 0.1-1 parts 2-methylimidazole, 1-3 parts antioxidant, 10-20 parts flame retardant, 1-3 parts stabilizer, and 1-2 parts lubricant.

[0008] Preferably, the weight-average molecular weight of polylactic acid is 100,000-200,000.

[0009] Preferably, the inorganic filler is at least one of light calcium carbonate, zeolite powder, and silica.

[0010] Preferably, the antioxidant is antioxidant 1010.

[0011] Preferably, the flame retardant includes zirconium phosphate and ammonium polyphosphate, wherein the mass ratio of zirconium phosphate to ammonium polyphosphate is 1-5:1-2.

[0012] Preferably, the lubricant is a stearic acid-based lubricant and / or liquid paraffin.

[0013] Preferably, the stabilizer is zinc acetylacetonate or calcium-zinc stabilizer.

[0014] Preferably, the degradation aid is prepared by the following steps: adding stearic acid and montmorillonite to an ethanol aqueous solution and stirring for 1-2 hours, adding nanocellulose whiskers and acetylated starch, stirring at 50-60°C for 1-2 hours, adjusting the pH of the system to 4.0-4.5, adding amyloglucosidase, stirring at 58-62°C for 1-2 hours, adding zinc borate while stirring, stirring for 1-2 hours, cooling to room temperature, and spray drying.

[0015] This invention utilizes montmorillonite layers to form an oleophilic interface through intercalation with stearic acid, and nanocellulose whiskers and acetylated starch to form a three-dimensional network. This not only improves the rigidity of the material in the early stage, but also enhances the degradation effect by allowing esterases secreted by microorganisms to penetrate through the defects between the montmorillonite layers during the degradation stage.

[0016] More preferably, the mass ratio of stearic acid, montmorillonite, nanocellulose whiskers, acetylated starch, amyloglucosidase, and zinc borate is 1-3:10-30:5-15:5-10:1-2:1-2.

[0017] The above-mentioned process for preparing biodegradable PET sheets includes the following steps:

[0018] S1. Dry PET resin and PBAT resin at 50-90℃ respectively, mix them evenly, and then add polylactic acid, degradation aid, antioxidant, flame retardant, inorganic filler, stabilizer and lubricant and mix evenly to obtain a premix.

[0019] S2. Add graphene oxide to water and stir until uniform. Add zinc nitrate and 2-methylimidazole and stir until uniform. Stir at 80-90℃ for 5-15 hours. Cool to room temperature, filter, wash, vacuum dry, and pulverize. Mix the product with the premixed material until uniform, and then extrude and inject into molds.

[0020] Preferably, a twin-screw extruder is used for extrusion injection molding. The temperature of the first stage of the twin-screw extruder is 120-190℃, the temperature of the second stage is 200-220℃, the temperature of the third stage is 230-250℃, the temperature of the fourth stage is 240-260℃, the screw speed is 200-400 rpm, and the injection temperature is 260-270℃. Beneficial effects

[0021] This invention utilizes zinc nitrate and 2-methylimidazole to form a ZIF-8 type MOF, which is then deposited on a graphene oxide sheet structure. When combined with PET resin, it not only forms a multi-level carbon skeleton during combustion, effectively adsorbing the molten material, preventing it from dripping and eliminating the risk of secondary ignition, but also works in conjunction with flame retardants to form a dual effect of physical barrier and chemical inhibition, resulting in a significant flame retardant effect.

[0022] This invention uses PET substrate combined with PBAT resin and polylactic acid as the substrate. It can not only be degraded by esterases secreted by microorganisms after disposal, but also, with the help of degradation aids, can promote the hydrolysis of the sheet in a humid and hot environment and provide a degradation channel for microorganisms in the later stage. It can effectively improve the microenvironment inside the PET degradable sheet, thereby making the PET degradable sheet more easily degraded by microorganisms and improving the biodegradability of the PET degradable sheet.

[0023] The degradation aid of this invention utilizes montmorillonite sheets intercalated with stearic acid to form an oleophilic interface, and nanocellulose whiskers and acetylated starch to form a three-dimensional network. ZIF-8 type MOF and graphene oxide synergistically enhance the interfacial effect, and when combined with PBAT and PLA, it balances strength and toughness, significantly improves mechanical properties, and helps to simultaneously improve the mechanical properties and biodegradability of PET degradable sheets.

[0024] This invention can significantly improve the flame retardant and anti-dripping effect of PET materials while maintaining good mechanical properties, and it also has significant biodegradability, thus having broad market and social benefits. Attached Figure Description

[0025] Figure 1 The image shows a comparison of the tensile strength and notched impact strength of the PET polyester biodegradable plastic sheets obtained in Example 5 and Comparative Examples 1-2.

[0026] Figure 2The graph shows a comparison of the heat distortion temperature and limiting oxygen index of the PET polyester biodegradable plastic sheets obtained in Example 5 and Comparative Examples 1-2.

[0027] Figure 3 The biodegradation rate curves are for the PET polyester biodegradable plastic sheets obtained in Example 5 and Comparative Examples 1-2. Detailed Implementation

[0028] The present invention will be further explained below with reference to specific embodiments.

[0029] The PET resin used below is from DuPont, USA, grade FR530CS WT597. The PBAT resin used below is from Lanshan Tunhe, grade TH801T. The polylactic acid used below is from Toray Industries, Japan, grade V554R10. The acetylated starch used below is from Guomin Starch, with a degree of acetyl substitution of 2. The nanocellulose whiskers used below are from Beijing Demoudao Jin Technology Co., Ltd., model CNWs-50, with a diameter of 10-50 nm and a length of 100-500 nm. The amyloglucosidase used below is from Yimoujiu (Lianyungang, Jiangsu) Biotechnology Co., Ltd. Example 1

[0030] A biodegradable PET polyester plastic sheet comprises the following raw materials: 80g PET resin, 10g PBAT resin, 5g polylactic acid, 5g degradation aid, 10g light calcium carbonate, 1g graphene oxide, 1g zinc nitrate, 0.1g 2-methylimidazole, 1g antioxidant 1010, 10g flame retardant, 1g zinc acetylacetone, and 1g calcium stearate. The flame retardant is composed of zirconium phosphate and ammonium polyphosphate in a 1:1 mass ratio.

[0031] The degradation aid is prepared by the following steps: 1g of stearic acid and 10g of montmorillonite are added to 40g of 40% ethanol aqueous solution and stirred for 1h at a stirring speed of 100r / min. 5g of nanocellulose whiskers and 5g of acetylated starch are added and stirred at 50℃ for 1h. The pH of the system is adjusted to 4.0-4.5. 1g of amylase is added and stirred at 58℃ for 1h. 1g of zinc borate is added while stirring and stirred for 1h. The mixture is then cooled to room temperature and spray-dried.

[0032] The above-mentioned process for preparing biodegradable PET sheets includes the following steps:

[0033] S1. Dry PET resin and PBAT resin separately at 50℃, mix them evenly, then add polylactic acid, degradation aid, antioxidant, flame retardant, light calcium carbonate, zinc acetylacetonate and calcium stearate and mix evenly at a mixing speed of 500r / min to obtain a premix.

[0034] S2. Add graphene oxide to 20g of water and stir until uniform. Add zinc nitrate and 2-methylimidazole and stir until uniform. Stir at 80℃ for 5 hours, cool to room temperature, filter, wash, vacuum dry, and pulverize. Mix the product with the premix and feed it into a twin-screw extruder for injection molding. The temperature of the first section of the twin-screw extruder is 120℃, the temperature of the second section is 200℃, the temperature of the third section is 230℃, the temperature of the fourth section is 240℃, the screw speed is 200rpm, and the injection molding temperature is 260℃. Example 2

[0035] A biodegradable PET polyester plastic sheet comprises the following raw materials: 140g PET resin, 30g PBAT resin, 15g polylactic acid, 15g degradation aid, 30g light calcium carbonate, 3g graphene oxide, 2g zinc nitrate, 1g 2-methylimidazole, 3g antioxidant 1010, 20g flame retardant, 3g zinc acetylacetone, and 2g calcium stearate. The flame retardant is composed of zirconium phosphate and ammonium polyphosphate in a mass ratio of 5:2.

[0036] The degradation aid is prepared by the following steps: 3g of stearic acid and 30g of montmorillonite are added to 60g of 60% ethanol aqueous solution and stirred for 2h at a stirring speed of 500r / min. 15g of nanocellulose whiskers and 10g of acetylated starch are added and stirred at 56℃ for 2h. The pH of the system is adjusted to 4.0-4.5. 2g of amylase is added and stirred at 62℃ for 2h. Under stirring, 2g of zinc borate is added and stirred for 2h. The mixture is then cooled to room temperature and spray-dried.

[0037] The above-mentioned process for preparing biodegradable PET sheets includes the following steps:

[0038] S1. Dry PET resin and PBAT resin separately at 90℃, mix them evenly, then add polylactic acid, degradation aid, antioxidant, flame retardant, light calcium carbonate, zinc acetylacetonate and calcium stearate and mix evenly at a mixing speed of 700r / min to obtain a premix.

[0039] S2. Add graphene oxide to 40g of water and stir until homogeneous. Add zinc nitrate and 2-methylimidazole and stir until homogeneous. Stir at 90℃ for 15h, cool to room temperature, filter, wash, vacuum dry, and pulverize. Mix the product with the premixed material and feed it into a twin-screw extruder for injection molding. The temperature of the first section of the twin-screw extruder is 190℃, the temperature of the second section is 220℃, the temperature of the third section is 250℃, the temperature of the fourth section is 260℃, the screw speed is 400rpm, and the injection molding temperature is 270℃. Example 3

[0040] A biodegradable PET polyester plastic sheet comprises the following raw materials: 90g PET resin, 25g PBAT resin, 8g polylactic acid, 13g degradation aid, 15g silica, 2.5g graphene oxide, 1.3g zinc nitrate, 0.8g 2-methylimidazole, 1.5g antioxidant 1010, 25g flame retardant, 1.5g zinc acetylacetonate, and 1.8g liquid paraffin. The flame retardant is composed of zirconium phosphate and ammonium polyphosphate in a mass ratio of 2:1.7.

[0041] The degradation aid was prepared using the following steps: 1.5g of stearic acid and 25g of montmorillonite were added to 45g of a 55% ethanol aqueous solution and stirred for 80min at a stirring speed of 400r / min. 8g of nanocellulose whiskers and 9g of acetylated starch were added, and the mixture was stirred at 52℃ for 100min. The pH of the system was adjusted to 4.0-4.5, and 1.2g of amylase was added. The mixture was stirred at 61℃ for 80min. Under stirring, 1.7g of zinc borate was added, and the mixture was stirred for another 80min. The mixture was then cooled to room temperature and spray-dried.

[0042] The above-mentioned process for preparing biodegradable PET sheets includes the following steps:

[0043] S1. Dry PET resin and PBAT resin at 80℃ respectively, mix them evenly, then add polylactic acid, degradation aid, antioxidant, flame retardant, fumed silica, zinc acetylacetonate, and liquid paraffin and mix evenly at a mixing speed of 550 r / min to obtain a premix.

[0044] S2. Add graphene oxide to 35g of water and stir until uniform. Add zinc nitrate and 2-methylimidazole and stir until uniform. Stir at 82℃ for 12h, cool to room temperature, filter, wash, vacuum dry, and pulverize. Mix the product with the premix and feed it into a twin-screw extruder for injection molding. The temperature of the first section of the twin-screw extruder is 140℃, the temperature of the second section is 215℃, the temperature of the third section is 235℃, the temperature of the fourth section is 255℃, the screw speed is 300rpm, and the injection molding temperature is 265℃. Example 4

[0045] A biodegradable PET polyester plastic sheet comprises the following raw materials: 100g PET resin, 20g PBAT resin, 10g polylactic acid, 10g degradation aid, 18g silica, 1.7g graphene oxide, 1.5g zinc nitrate, 0.6g 2-methylimidazole, 1.8g antioxidant 1010, 21g flame retardant, 2.2g zinc acetylacetonate, and 1.5g liquid paraffin. The flame retardant is composed of zirconium phosphate and ammonium polyphosphate in a mass ratio of 3:1.5.

[0046] The degradation aid was prepared using the following steps: 1.7g of stearic acid and 22g of montmorillonite were added to 51g of a 47% ethanol aqueous solution and stirred for 90min at a stirring speed of 300r / min. 11g of nanocellulose whiskers and 8g of acetylated starch were added, and the mixture was stirred at 52℃ for 90min. The pH of the system was adjusted to 4.0-4.5, and 1.6g of amylase was added. The mixture was stirred at 60℃ for 90min. Under stirring, 1.5g of zinc borate was added, and the mixture was stirred for 90min. The mixture was then cooled to room temperature and spray-dried.

[0047] The above-mentioned process for preparing biodegradable PET sheets includes the following steps:

[0048] S1. Dry PET resin and PBAT resin at 70℃ respectively, mix them evenly, then add polylactic acid, degradation aid, antioxidant, flame retardant, silica, zinc acetylacetonate and liquid paraffin and mix evenly at a mixing speed of 620r / min to obtain a premix.

[0049] S2. Add graphene oxide to 32g of water and stir until homogeneous. Add zinc nitrate and 2-methylimidazole and stir until homogeneous. Stir at 85℃ for 10h, cool to room temperature, filter, wash, vacuum dry, and pulverize. Mix the product with the premixed material and feed it into a twin-screw extruder for injection molding. The temperature of the first section of the twin-screw extruder is 152℃, the temperature of the second section is 207℃, the temperature of the third section is 242℃, the temperature of the fourth section is 247℃, the screw speed is 320rpm, and the injection molding temperature is 265℃. Example 5

[0050] A biodegradable PET polyester plastic sheet comprises the following raw materials: 100g PET resin, 20g PBAT resin, 10g polylactic acid, 10g degradation aid, 20g zeolite powder, 2g graphene oxide, 1.5g zinc nitrate, 0.6g 2-methylimidazole, 10102g antioxidant, 20g flame retardant, 2g zinc acetylacetonate, and 1.5g ethylene bis-stearamide. The flame retardant is composed of zirconium phosphate and ammonium polyphosphate in a mass ratio of 3:1.5.

[0051] The degradation aid is prepared by the following steps: 2g of stearic acid and 20g of montmorillonite are added to 50g of 50% ethanol aqueous solution and stirred for 90min at a stirring speed of 300r / min. 10g of nanocellulose whiskers and 8g of acetylated starch are added and stirred at 53℃ for 90min. The pH of the system is adjusted to 4.0-4.5. 1.5g of amylase is added and stirred at 60℃ for 90min. Under stirring, 1.5g of zinc borate is added and stirred for 90min. The mixture is then cooled to room temperature and spray-dried.

[0052] The above-mentioned process for preparing biodegradable PET sheets includes the following steps:

[0053] S1. Dry PET resin and PBAT resin at 70℃ respectively, mix them evenly, then add polylactic acid, degradation aid, antioxidant, flame retardant, zeolite powder, zinc acetylacetonate, and ethylene bis-stearamide and mix evenly at a mixing speed of 600r / min to obtain a premix.

[0054] S2. Add graphene oxide to 30g of water and stir until uniform. Add zinc nitrate and 2-methylimidazole and stir until uniform. Stir at 85℃ for 10h, cool to room temperature, filter, wash, vacuum dry, and pulverize. Mix the product with the premix and feed it into a twin-screw extruder for injection molding. The temperature of the first section of the twin-screw extruder is 160℃, the temperature of the second section is 210℃, the temperature of the third section is 240℃, the temperature of the fourth section is 250℃, the screw speed is 350rpm, and the injection molding temperature is 265℃. Comparative Example 1

[0055] A biodegradable PET polyester plastic sheet comprises the following raw materials: 100g PET resin, 20g PBAT resin, 10g polylactic acid, 10g degradation aid, 20g zeolite powder, 2g graphene oxide, 1.5g zinc nitrate, 0.6g 2-methylimidazole, 10102g antioxidant, 20g flame retardant, 2g zinc acetylacetonate, and 1.5g ethylene bis-stearamide. The flame retardant is composed of zirconium phosphate and ammonium polyphosphate in a mass ratio of 3:1.5.

[0056] The degradation aid is prepared by the following steps: 2g of stearic acid and 20g of montmorillonite are added to 50g of 50% ethanol aqueous solution and stirred for 90min at a stirring speed of 300r / min. 10g of nanocellulose whiskers and 8g of acetylated starch are added and stirred at 53℃ for 90min. The pH of the system is adjusted to 4.0-4.5. 1.5g of amylase is added and stirred at 60℃ for 90min. Under stirring, 1.5g of zinc borate is added and stirred for 90min. The mixture is then cooled to room temperature and spray-dried.

[0057] The above-mentioned process for preparing biodegradable PET sheets includes the following steps:

[0058] S1. Dry PET resin and PBAT resin at 70℃ respectively, mix them evenly, then add polylactic acid, degradation aid, antioxidant, flame retardant, zeolite powder, zinc acetylacetonate, and ethylene bis-stearamide and mix evenly at a mixing speed of 600r / min to obtain a premix.

[0059] S2. Add zinc nitrate and 2-methylimidazole to 30g of water and stir evenly. Stir at 85℃ for 10h, cool to room temperature, filter, wash, vacuum dry, pulverize, and then add graphene oxide and mix evenly. Next, add the premix and mix evenly, then feed it into a twin-screw extruder for injection molding. The temperature of the first section of the twin-screw extruder is 160℃, the temperature of the second section is 210℃, the temperature of the third section is 240℃, the temperature of the fourth section is 250℃, the screw speed is 350rpm, and the injection molding temperature is 265℃. Comparative Example 2

[0060] A biodegradable PET polyester plastic sheet comprises the following raw materials: 100g PET resin, 20g PBAT resin, 10g polylactic acid, 10g degradation aid, 20g zeolite powder, 2g graphene oxide, 1.5g zinc nitrate, 0.6g 2-methylimidazole, 10102g antioxidant, 20g flame retardant, 2g zinc acetylacetonate, and 1.5g ethylene bis-stearamide. The flame retardant is composed of zirconium phosphate and ammonium polyphosphate in a mass ratio of 3:1.5.

[0061] The degradation aid is prepared by the following steps: stir 2g stearic acid, 20g montmorillonite, 10g nanocellulose whiskers, 8g acetylated starch and 1.5g zinc borate for 90min.

[0062] The above-mentioned process for preparing biodegradable PET sheets includes the following steps:

[0063] S1. Dry PET resin and PBAT resin at 70℃ respectively, mix them evenly, then add polylactic acid, degradation aid, antioxidant, flame retardant, zeolite powder, zinc acetylacetonate, and ethylene bis-stearamide and mix evenly at a mixing speed of 600r / min to obtain a premix.

[0064] S2. Add graphene oxide to 30g of water and stir until uniform. Add zinc nitrate and 2-methylimidazole and stir until uniform. Stir at 85℃ for 10h, cool to room temperature, filter, wash, vacuum dry, and pulverize. Mix the product with the premix and feed it into a twin-screw extruder for injection molding. The temperature of the first section of the twin-screw extruder is 160℃, the temperature of the second section is 210℃, the temperature of the third section is 240℃, the temperature of the fourth section is 250℃, the screw speed is 350rpm, and the injection molding temperature is 265℃.

[0065] The tensile strength of the PET polyester biodegradable plastic sheets obtained in Example 5 and Comparative Examples 1-2 was determined according to GB / T 1040.1-2018 "Determination of tensile properties of plastics - Part 1: General". The notched impact strength of the PET polyester biodegradable plastic sheets obtained in Example 5 and Comparative Examples 1-2 was determined according to ASTM D256-2010E1.

[0066] like Figure 1 As shown, the PET polyester biodegradable plastic sheet obtained in Example 5 has the highest tensile strength and impact strength, which is better than that of Comparative Examples 1-2 (P<0.05).

[0067] The heat distortion temperature of the PET polyester biodegradable plastic sheets obtained in Example 5 and Comparative Examples 1-2 was determined according to ASTM D648-2018. The limiting oxygen index of the PET polyester biodegradable plastic sheets obtained in Example 5 and Comparative Examples 1-2 was determined according to GB / T 2406.1-2008 "Determination of flammability of plastics by oxygen index method - Part 1: Guidelines".

[0068] like Figure 2 As shown, the PET polyester biodegradable plastic sheet obtained in Example 5 had the highest heat distortion temperature and limiting oxygen index, which were better than those of Comparative Example 1 (P < 0.05), but there was no significant difference compared with Comparative Example 2.

[0069] The combustion performance of the PET polyester biodegradable plastic sheets obtained in Example 5 and Comparative Examples 1-2 was determined in accordance with GB / T 2408-2021 "Determination of the flammability of plastics - Horizontal and Vertical Methods". The results are shown in Table 1.

[0070] Table 1 shows the combustion performance results of the sheets obtained in Example 5 and Comparative Examples 1-2.

[0071]

[0072] As can be seen from Table 1, the PET polyester biodegradable plastic sheet obtained in Example 5 has the best flame retardant and anti-dripping properties.

[0073] The degradation performance of the PET polyester biodegradable plastic sheets obtained in Example 5 and Comparative Examples 1-2 was tested according to GB / T 19277.1-2011 "Determination of the final aerobic biodegradability of materials under controlled composting conditions by measuring the amount of carbon dioxide released - Part 1: General method". In a 2L test system, each group of sheets was used as the organic carbon source, and the test mixture was aerated with carbon dioxide-free air at a controlled rate. The degradation rate was determined by measuring the amount of carbon dioxide produced. 240g of culture soil was mixed with 40g of each group of sheets and 40g of microcrystalline cellulose, respectively, with 240g of culture soil serving as a blank control. Distilled water was added to adjust the humidity of the mixture to 50%. The compost container was placed in a test environment at (58±2)℃, and the test system was aerated with saturated air (carbon dioxide-free) at a flow rate of 0.05L / min. The test was conducted at (58±2)℃. The biodegradability rate of the test material was determined by the ratio of the actual amount of carbon dioxide produced by the test material during the test to the theoretical amount of carbon dioxide released by the test material.

[0074] like Figure 3 As shown, the degradation performance of the PET polyester biodegradable plastic sheets obtained in Example 5 and Comparative Example 1 is similar and better than that in Comparative Example 2.

[0075] The applicant believes that this invention utilizes zinc nitrate and 2-methylimidazole to form a ZIF-8 type MOF, which is then deposited on a graphene oxide sheet structure. Combined with PET resin, this not only forms a multi-level carbon skeleton during combustion, effectively adsorbing molten material, preventing dripping, and eliminating the risk of secondary ignition, but also works synergistically with flame retardants to achieve a dual effect of physical barrier and chemical inhibition, resulting in a significant flame-retardant effect. The degradation aid of this invention utilizes montmorillonite sheets intercalated with stearic acid to form an oleophilic interface, with nanocellulose whiskers and acetylated starch forming a three-dimensional network. The ZIF-8 type MOF and graphene oxide synergistically enhance the interfacial interaction, improving the crystallinity of PET through heterogeneous nucleation. Simultaneously, it balances strength and toughness when combined with PBAT and PLA, significantly improving mechanical properties and contributing to the simultaneous improvement of the mechanical properties and biodegradability of PET degradable sheets.

[0076] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A PET polyester-based degradable plastic sheet material, characterized by, The raw materials include, by mass fraction: PET resin 80-140 parts, PBAT resin 10-30 parts, polylactic acid 5-15 parts, degradation aid 5-15 parts, inorganic filler 10-30 parts, graphene oxide 1-3 parts, zinc nitrate 1-2 parts, 2-methylimidazole 0.1-1 part, antioxidant 1-3 parts, flame retardant 10-20 parts, stabilizer 1-3 parts, lubricant 1-2 parts; The degradation aid is prepared by the following steps: stearic acid and montmorillonite are added to an ethanol aqueous solution and stirred for 1-2 h, nano-cellulose whiskers and acetylated starch are added thereto, and stirring is performed at 50-60℃ for 1-2 h, the pH value of the system is adjusted to 4.0-4.5, starch glucosidase is added, and stirring is performed at 58-62℃ for 1-2 h, zinc borate is added thereto under stirring for 1-2 h, and then the system is cooled to room temperature and spray dried; The mass ratio of stearic acid, montmorillonite, nano-cellulose whiskers, acetylated starch, starch glucosidase and zinc borate is 1-3:10-30:5-15:5-10:1-2:1-2; The PET polyester degradable plastic sheet is prepared by the following steps: S1, the PET resin and PBAT resin are uniformly mixed, and then polylactic acid, degradation aid, antioxidant, flame retardant, inorganic filler, stabilizer and lubricant are uniformly mixed to obtain a premix; S2, the graphene oxide is added to water and stirred uniformly, zinc nitrate and 2-methylimidazole are added and stirred uniformly, stirring is performed at 80-90℃ for 5-15 h, the system is cooled to room temperature, filtered, washed, vacuum dried and pulverized; the product is uniformly mixed with the premix, and extrusion injection molding is performed.

2. The PET polyester-based degradable plastic sheet according to claim 1, characterized in that, The weight average molecular weight of the polylactic acid is 100000-200000.

3. The PET polyester-based degradable plastic sheet as claimed in claim 1, wherein, The inorganic filler is at least one of light calcium carbonate, zeolite powder and white carbon black.

4. The PET polyester-based degradable plastic sheet as claimed in claim 1, wherein, The antioxidant is antioxidant 1010.

5. The PET polyester-based degradable plastic sheet as claimed in claim 1, wherein, The flame retardant includes: The mass ratio of zirconium phosphate and ammonium polyphosphate is 1-5:1-2.

6. The PET polyester-based degradable plastic sheet as claimed in claim 1, wherein, The lubricant is a stearic acid lubricant and / or liquid paraffin.

7. The PET polyester-based degradable plastic sheet as claimed in claim 1, wherein, The stabilizer is zinc acetylacetone or calcium zinc stabilizer.

8. A process for the preparation of PET polyester-based degradable plastic sheeting as claimed in any one of claims 1 to 7, wherein, The PET polyester degradable plastic sheet is prepared by the following steps: S1, the PET resin and PBAT resin are uniformly mixed, and then polylactic acid, degradation aid, antioxidant, flame retardant, inorganic filler, stabilizer and lubricant are uniformly mixed to obtain a premix; S2, the graphene oxide is added to water and stirred uniformly, zinc nitrate and 2-methylimidazole are added and stirred uniformly, stirring is performed at 80-90℃ for 5-15 h, the system is cooled to room temperature, filtered, washed, vacuum dried and pulverized; the product is uniformly mixed with the premix, and extrusion injection molding is performed.

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