High-strength degradable plastic and preparation method thereof
By preparing a combination of diatomaceous earth-supported sodium polyacrylate reinforced masterbatch and magnesium oxide, the problem of low degradation efficiency or insufficient strength of traditional plastics in alkaline regions was solved, achieving a synergistic effect of high strength and rapid degradation.
Patent Information
- Application Number
- CN202511518636.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-23
- Publication Date
- 2025-12-12
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Traditional biodegradable plastics have low degradation efficiency or insufficient strength in alkaline and low-management areas, making it difficult to meet the synergistic requirements of high strength and rapid degradation.
Using PBAT, PLA, nano-calcium carbonate, zinc stearate, glycerides, magnesium oxide, sodium citrate, diatomaceous earth, sodium acrylate and other components, a diatomaceous earth-supported sodium polyacrylate reinforced masterbatch is prepared. Combined with magnesium oxide, it forms a highly efficient degradation system in an alkaline environment, ensuring uniform dispersion and stable binding of the components.
It achieves a synergistic effect of high strength and rapid degradation in alkaline environments, avoiding the problem of reduced degradation efficiency of traditional plastics when there is insufficient light, and ensuring the high strength and rapid degradation performance of plastics in alkaline regions.
Smart Images
Figure CN121108548A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of biodegradable plastic preparation technology, and more specifically, to a high-strength biodegradable plastic and its preparation method. Background Technology
[0002] In alkaline areas with low management intensity, such as urban-rural transition zones, demolition ruins, roadside areas, and industrial waste impact areas, the soil pH value is high due to factors such as cement residue, de-icing agent use, and industrial emissions. The special environmental characteristics place stringent requirements on the performance of plastics. Currently, traditional biodegradable plastics have significant drawbacks in these areas: plastics that rely on photosensitizers for degradation lose their degradation efficiency drastically after being covered by soil and deprived of sunlight; while biodegradable plastics with added starch are easy to degrade, their strength is insufficient to meet practical needs such as packaging and load-bearing, thus limiting their applicability in these areas; and existing biodegradable plastic bags cannot meet the synergistic requirements of high strength and rapid degradation in alkaline environments. Therefore, there is an urgent need to develop a high-strength biodegradable plastic and a suitable preparation method for these areas.
[0003] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention
[0004] In view of the problems in the related technologies, the present invention proposes a high-strength biodegradable plastic and a preparation method thereof, so as to overcome the above-mentioned technical problems existing in the existing related technologies.
[0005] Therefore, the specific technical solution adopted by the present invention is as follows: A method for preparing high-strength biodegradable plastic, the method comprising the following steps: S1. Prepare the raw materials for plastic preparation. The raw materials consist of PBAT, PLA, nano calcium carbonate, zinc stearate, glycerides, magnesium oxide, sodium citrate, diatomaceous earth, sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide, hydrochloric acid, anhydrous ethanol, silane coupling agent KH560, molten stearic acid, and BHT antioxidant. The raw materials are then pretreated. S2. A reinforced masterbatch was prepared by using nano-magnesium oxide, sodium citrate and diatomaceous earth to support sodium polyacrylate. S3. Mix the ingredients made from the raw materials and blow mold them into a film.
[0006] In a preferred embodiment, the raw materials for preparing the plastic are composed of PBAT, PLA, nano-calcium carbonate, zinc stearate, glycerides, magnesium oxide, sodium citrate, diatomaceous earth, sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide, hydrochloric acid, anhydrous ethanol, silane coupling agent KH560, molten stearic acid, and BHT antioxidant. The raw materials are then pretreated in the following steps: S11. Prepare raw materials: PBAT, PLA, nano calcium carbonate, zinc stearate, glycerides, magnesium oxide, sodium citrate, diatomaceous earth, sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide, hydrochloric acid, anhydrous ethanol, silane coupling agent KH560, molten stearic acid, BHT antioxidant. S12. The diatomaceous earth was acid-washed and purified to prepare a 10% hydrochloric acid solution. The diatomaceous earth was then immersed in the 10% hydrochloric acid solution, and the solid-liquid ratio was controlled at 1:5. The mixture was mechanically stirred for 60 minutes to dissolve the metal impurities. The mixture was then repeatedly washed with water until it was neutral, and the pH of the filtrate was 7.0±0.2. The mixture was then transferred to a 120℃ hot air drying oven for 6 hours and the moisture content was tested to be ≤0.5%. Finally, the mixture was pulverized to 80 mesh and sieved to control the particle size to be ≤180μm. S13. Prepare sodium polyacrylate supported on diatomaceous earth using acid-washed and purified diatomaceous earth. S14. Mix KH560 stock solution with anhydrous ethanol at a mass ratio of 1:9, and then add deionized water to prepare a silane coupling agent KH560 ethanol solution, wherein the deionized water accounts for 2% to 5% of the mass of KH560; S15. Take magnesium oxide powder with a particle size of 30-50 nm and place it in a vacuum drying oven at 60℃ for 4 hours to dehydrate. Mix it with silane coupling agent KH560 ethanol solution by wet method. The mass ratio of magnesium oxide to silane coupling agent KH560 ethanol solution is 100:1. After drying at 80℃, put it into a planetary ball mill, set the speed to 300 rpm, and the ball milling time is 30 minutes. After the ball milling is completed, pass it through a 400-mesh sieve to obtain activated magnesium oxide. S16. The selected glycerides are epoxidized soybean oil with an epoxy value ≥6.0. 0.1% BHT antioxidant is added to it. After filtration through a 10μm filter membrane, it is stored in the dark and the storage temperature is controlled below 25℃. S17. Spread PBAT and PLA granules in layers in a hot air circulating drying oven, set the temperature to 80℃ and treat for 8 hours. Turn the material over every 2 hours during the treatment. After treatment, use the Karl Fischer method to test the moisture content and ensure that the moisture content is ≤0.05%.
[0007] In a preferred embodiment, the preparation of diatomaceous earth-supported sodium polyacrylate using acid-washed and purified diatomaceous earth includes the following steps: S131. Diatomaceous earth and sodium acrylate are added to the reactor in a mass ratio of 1:2, and ammonium persulfate and N,N-methylenebisacrylamide are added. The reactor is then evacuated to -0.08 MPa and heated to 60°C. The reaction is carried out for 120 minutes to generate hydrogel. S132. Wash the hydrogel three times with anhydrous ethanol, dry it under vacuum at 60°C for 12 hours, then pulverize it into 100-200μm particles and verify that the swelling rate is ≥300g / g.
[0008] In a preferred embodiment, the preparation of the reinforced masterbatch using sodium polyacrylate supported on diatomaceous earth (made from nano-magnesium oxide, sodium citrate, and diatomaceous earth) includes the following steps: S21. Place magnesium oxide and sodium citrate into a three-dimensional motion mixer in a clean room with humidity ≤30%, add 0.5% fumed silica as an anti-caking agent, and mix at 25 rpm for 30 minutes to ensure uniform powder dispersion. S22. In zones 1-3 of the twin-screw extruder, premixed powder is added, and zinc stearate is added simultaneously. The screw speed is set to 100 rpm to form a preliminary melt mixture. PLA is injected into zones 4-6 of the twin-screw extruder to fully melt and coat the powder mixture, while controlling the melt viscosity at 3500-4000 mPa·s. Diatomaceous earth-loaded sodium polyacrylate composite particles are added to zones 7-9 of the twin-screw extruder. The shear speed is set to 150 rpm, and a -0.08 MPa vacuum devolatilization is started simultaneously for 2 minutes to remove moisture and volatiles, ensuring that the SAP activity retention rate is ≥95%. In zones 10-12, the heat-sensitive components are cooled and protected. The melt is extruded through a custom coat hanger die, with the cutter speed set to 300 rpm, the water temperature at 25±2℃, and an underwater pelletizing system is used to generate homogeneous masterbatch particles with a diameter of 3 mm and a length of 2 mm. The temperature in zones 1-3 of the twin-screw extruder is 80-90℃, the temperature in zones 4-6 is 150-155℃, the temperature in zones 7-9 is 160-165℃, and the temperature in zones 10-12 is 145-150℃. S23. Set the speed to 2000 rpm for 5 minutes. Remove the surface moisture of the wet masterbatch by centrifugal dewatering machine and transfer it to a fluidized bed dryer. Set the fluidized bed dryer to 60℃ hot air and 2m / s for 2 hours to control the moisture content to ≤0.03%. Then, screen out irregularly shaped particles with a particle size <1mm or >4mm.
[0009] In a preferred embodiment, the ingredients made from raw materials are mixed and blown into a film: S31. Accurately weigh PBAT, fortified masterbatch, nano calcium carbonate, epoxidized soybean oil, and zinc stearate. S32. Add solid materials including PBAT, reinforced masterbatch, and calcium carbonate into a high-speed mixer and premix at 800 rpm for 3 minutes. Then spray with epoxidized soybean oil and continue stirring for 2 minutes. S33. Transfer the mixture into a co-rotating twin-screw extruder, set the screw speed to 180 rpm, and then turn on the -0.06 MPa vacuum devolatilization; finally, the melt is filtered through a 200-mesh filter and then conveyed to the three-layer co-extrusion blown film die. S34 uses a stacked three-layer die blow molding process.
[0010] A high-strength biodegradable plastic, wherein the plastic is made of any one of the high-strength biodegradable plastics and preparation methods described above, and specifically includes the following components: S1, PBAT, 50-70 parts; reinforced masterbatch, 20-30 parts; activated nano calcium carbonate, 4-8 parts; epoxidized soybean oil, 4-8 parts; zinc stearate, 0.5-3 parts. S2, the reinforced masterbatch consists of sodium citrate, diatomaceous earth-supported sodium polyacrylate, magnesium oxide, and PLA, with sodium citrate comprising 5-10 parts, diatomaceous earth-supported sodium polyacrylate comprising 9-12 parts, magnesium oxide comprising 12-15 parts, and PLA comprising 50-75 parts.
[0011] In a preferred embodiment, the specific mass fractions of the following components are as follows: 50-70 parts PBAT, 20-30 parts reinforced masterbatch, 4-8 parts activated nano-calcium carbonate, 4-8 parts epoxidized soybean oil, and 0.5-3 parts zinc stearate. S11, PBAT, 64 parts; reinforced masterbatch, 25 parts; activated nano calcium carbonate, 5 parts; epoxidized soybean oil, 5 parts; zinc stearate, 1 part.
[0012] In a preferred embodiment, the specific mass fractions of sodium citrate (5-10 parts), diatomaceous earth-supported sodium polyacrylate (9-12 parts), magnesium oxide (12-15 parts), and PLA (50-75 parts) are as follows: S21, the reinforced masterbatch is composed of sodium citrate, sodium polyacrylate supported on diatomaceous earth, magnesium oxide, and PLA, wherein sodium citrate is 6.9 parts, sodium polyacrylate supported on diatomaceous earth is 10.3 parts, magnesium oxide is 13.8 parts, and PLA is 69 parts.
[0013] The beneficial effects of this invention are as follows: 1. This invention aims to prepare a high-strength biodegradable plastic for alkaline areas with low management intensity, including urban-rural transition zones, demolition ruins, roadside areas, and industrial waste impact zones. This plastic achieves synergistic performance of high strength and rapid degradation through specific component design. In alkaline areas with low management intensity, the soil pH value is usually between 7 and 10 due to factors such as cement, de-icing agents, and industrial emissions. Traditional biodegradable plastics have obvious defects in this environment: plastics with added photosensitizers lose light conditions after being covered by soil, resulting in a significant decrease in degradation efficiency; plastics with added starch are easy to degrade, but their strength is insufficient to meet practical needs such as packaging and load-bearing. This invention, by adding sodium citrate, diatomaceous earth-supported sodium polyacrylate, and magnesium oxide, can form a highly efficient degradation system in alkaline environments. Sodium citrate can regulate the local microenvironment and accelerate the hydrolysis reaction of materials under alkaline conditions; diatomaceous earth-supported sodium polyacrylate has excellent water absorption and swelling properties, which can promote the rapid disintegration of the material structure in a moist alkaline environment; magnesium oxide, as an alkaline enhancer, works synergistically with alkaline substances in the environment to further improve the degradation rate.
[0014] 2. This invention achieves uniform dispersion and stable combination of functional components by preparing a reinforced masterbatch from sodium citrate, diatomaceous earth-supported sodium polyacrylate, magnesium oxide, and PLA before adding the masterbatch. This avoids the problems of magnesium oxide powder agglomeration and uneven diatomaceous earth dispersion that easily occur when adding the masterbatch directly, ensuring the consistency of the overall performance of the plastic and reducing strength fluctuations or degradation rate differences caused by local component imbalances. At the same time, the masterbatch treatment can protect the water absorption of heat-sensitive components, including diatomaceous earth-supported sodium polyacrylate, from damage caused by high temperature and high shear during subsequent processing. Its activity is retained through pre-dispersion and encapsulation structure, allowing the material to maintain high strength during use and quickly exert its degradation function after disposal. In addition, the standardized production of the masterbatch facilitates precise control of the proportion of each component and simplifies the subsequent batching and mixing process. Therefore, compared with directly mixing the components, directly preparing the masterbatch has significant advantages. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 This is a flowchart of a method for preparing high-strength biodegradable plastic according to an embodiment of the present invention. Detailed Implementation
[0017] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.
[0018] According to embodiments of the present invention, a high-strength biodegradable plastic and a method for preparing it are provided.
[0019] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Figure 1 As shown, a method for preparing high-strength biodegradable plastic according to an embodiment of the present invention includes the following steps: S1. Prepare the raw materials for plastic preparation. The raw materials consist of PBAT, PLA, nano calcium carbonate, zinc stearate, glycerides, magnesium oxide, sodium citrate, diatomaceous earth, sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide, hydrochloric acid, anhydrous ethanol, silane coupling agent KH560, molten stearic acid, and BHT antioxidant. The raw materials are then pretreated. Further, the raw materials for plastic preparation are prepared, consisting of PBAT, PLA, nano-calcium carbonate, zinc stearate, glycerides, magnesium oxide, sodium citrate, diatomaceous earth, sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide, hydrochloric acid, anhydrous ethanol, silane coupling agent KH560, molten stearic acid, and BHT antioxidant. The raw materials are then pretreated as follows: S11. Prepare raw materials: PBAT, PLA, nano calcium carbonate, zinc stearate, glycerides, magnesium oxide, sodium citrate, diatomaceous earth, sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide, hydrochloric acid, anhydrous ethanol, silane coupling agent KH560, molten stearic acid, BHT antioxidant. S12. The diatomaceous earth was acid-washed and purified to prepare a 10% hydrochloric acid solution. The diatomaceous earth was then immersed in the 10% hydrochloric acid solution, and the solid-liquid ratio was controlled at 1:5. The mixture was mechanically stirred for 60 minutes to dissolve the metal impurities. The mixture was then repeatedly washed with water until it was neutral, and the pH of the filtrate was 7.0±0.2. The mixture was then transferred to a 120℃ hot air drying oven for 6 hours and the moisture content was tested to be ≤0.5%. Finally, the mixture was pulverized to 80 mesh and sieved to control the particle size to be ≤180μm. It should be noted that acid washing and purification of diatomaceous earth can efficiently dissolve metal oxides such as iron, aluminum, and calcium, as well as organic impurities, and open up its natural microporous structure, significantly enhancing the loading capacity and water absorption rate of subsequent sodium polyacrylate. At the same time, it eliminates the catalytic activity of metal ions on the thermal oxidative degradation of plastics and neutralizes the native alkalinity of diatomaceous earth, avoiding premature activation of the degradation system, ensuring the stability of plastic processing and storage life, and ultimately endowing diatomaceous earth with purer chemical properties and more efficient physical disintegration function. S13. Prepare sodium polyacrylate supported on diatomaceous earth using acid-washed and purified diatomaceous earth. Furthermore, the preparation of diatomaceous earth-supported sodium polyacrylate using acid-washed and purified diatomaceous earth includes the following steps: S131. Diatomaceous earth and sodium acrylate are added to the reactor in a mass ratio of 1:2, and ammonium persulfate and N,N-methylenebisacrylamide are added. The reactor is then evacuated to -0.08 MPa and heated to 60°C. The reaction is carried out for 120 minutes to generate hydrogel. S132. Wash the hydrogel three times with anhydrous ethanol, dry it under vacuum at 60°C for 12 hours, then pulverize it into 100-200μm particles and verify that the swelling rate is ≥300g / g.
[0020] S14. Mix KH560 stock solution with anhydrous ethanol at a mass ratio of 1:9, and then add deionized water to prepare a silane coupling agent KH560 ethanol solution, wherein the deionized water accounts for 2% to 5% of the mass of KH560; S15. Take magnesium oxide powder with a particle size of 30-50 nm and place it in a vacuum drying oven at 60℃ for 4 hours to dehydrate. Mix it with silane coupling agent KH560 ethanol solution by wet method. The mass ratio of magnesium oxide to silane coupling agent KH560 ethanol solution is 100:1. After drying at 80℃, put it into a planetary ball mill, set the speed to 300 rpm, and the ball milling time is 30 minutes. After the ball milling is completed, pass it through a 400-mesh sieve to obtain activated magnesium oxide. S16. The selected glycerides are epoxidized soybean oil with an epoxy value ≥6.0. 0.1% BHT antioxidant is added to it. After filtration through a 10μm filter membrane, it is stored in the dark and the storage temperature is controlled below 25℃. S17. Spread PBAT and PLA granules in layers in a hot air circulating drying oven, set the temperature to 80℃ and treat for 8 hours. Turn the material over every 2 hours during the treatment. After treatment, use the Karl Fischer method to test the moisture content and ensure that the moisture content is ≤0.05%.
[0021] It should be noted that pretreatment of raw materials can effectively improve the performance of each component and its compatibility with subsequent processing. Diatomaceous earth, after acid washing and purification, can remove metallic impurities, and after drying and pulverizing, it can ensure that the particle size and moisture content meet the standards, laying a good foundation for loading sodium polyacrylate. Magnesium oxide, after dehydration, coupling agent treatment and ball milling, can enhance its activity and dispersibility. Epoxidized soybean oil, filtered and stored with added antioxidants, can maintain its stability. PBAT and PLA, dried to low moisture content, can avoid adverse effects caused by moisture during processing. These pretreatments together ensure the high strength and biodegradability of the final plastic product. S2. A reinforced masterbatch was prepared by using nano-magnesium oxide, sodium citrate and diatomaceous earth to support sodium polyacrylate. Furthermore, the preparation of reinforced masterbatch using diatomaceous earth-supported sodium polyacrylate made from nano-magnesium oxide, sodium citrate, and diatomaceous earth includes the following steps: S21. Place magnesium oxide and sodium citrate into a three-dimensional motion mixer in a clean room with humidity ≤30%, add 0.5% fumed silica as an anti-caking agent, and mix at 25 rpm for 30 minutes to ensure uniform powder dispersion. S22. In zones 1-3 of the twin-screw extruder, premixed powder is added, and zinc stearate is added simultaneously. The screw speed is set to 100 rpm to form a preliminary melt mixture. PLA is injected into zones 4-6 of the twin-screw extruder to fully melt and coat the powder mixture, while controlling the melt viscosity at 3500-4000 mPa·s. Diatomaceous earth-loaded sodium polyacrylate composite particles are added to zones 7-9 of the twin-screw extruder. The shear speed is set to 150 rpm, and a -0.08 MPa vacuum devolatilization is started simultaneously for 2 minutes to remove moisture and volatiles, ensuring that the SAP activity retention rate is ≥95%. In zones 10-12, the heat-sensitive components are cooled and protected. The melt is extruded through a custom coat hanger die, with the cutter speed set to 300 rpm, the water temperature at 25±2℃, and an underwater pelletizing system is used to generate homogeneous masterbatch particles with a diameter of 3 mm and a length of 2 mm. S23. Set the speed to 2000 rpm for 5 minutes. Remove the surface moisture of the wet masterbatch by centrifugal dewatering machine and transfer it to a fluidized bed dryer. Set the fluidized bed dryer to 60℃ hot air and 2m / s for 2 hours to control the moisture content to ≤0.03%. Then, screen out irregularly shaped particles with a particle size <1mm or >4mm.
[0022] S3. Mix the ingredients made from the raw materials and blow mold them into a film.
[0023] Furthermore, the ingredients made from the raw materials are mixed and blown into a film: S31. Accurately weigh PBAT, fortified masterbatch, nano calcium carbonate, epoxidized soybean oil, and zinc stearate. S32. Add solid materials including PBAT, reinforced masterbatch, and calcium carbonate into a high-speed mixer and premix at 800 rpm for 3 minutes. Then spray with epoxidized soybean oil and continue stirring for 2 minutes. S33. Transfer the mixture into a co-rotating twin-screw extruder, set the screw speed to 180 rpm, and then turn on the -0.06 MPa vacuum devolatilization; finally, the melt is filtered through a 200-mesh filter and then conveyed to the three-layer co-extrusion blown film die. S34 uses a stacked three-layer die blow molding process.
[0024] A high-strength biodegradable plastic, comprising any one of the above-mentioned high-strength biodegradable plastics and its preparation method, specifically including the following components: S1, PBAT, 50-70 parts; reinforced masterbatch, 20-30 parts; activated nano calcium carbonate, 4-8 parts; epoxidized soybean oil, 4-8 parts; zinc stearate, 0.5-3 parts. S2, the reinforced masterbatch consists of sodium citrate, diatomaceous earth-supported sodium polyacrylate, magnesium oxide, and PLA, with sodium citrate comprising 5-10 parts, diatomaceous earth-supported sodium polyacrylate comprising 9-12 parts, magnesium oxide comprising 12-15 parts, and PLA comprising 50-75 parts.
[0025] Furthermore, the following components are present by weight: PBAT, 50-70 parts; fortified masterbatch, 20-30 parts; activated nano-calcium carbonate, 4-8 parts; epoxidized soybean oil, 4-8 parts; and zinc stearate, 0.5-3 parts. S11, PBAT, 64 parts; reinforced masterbatch, 25 parts; activated nano calcium carbonate, 5 parts; epoxidized soybean oil, 5 parts; zinc stearate, 1 part.
[0026] Furthermore, the following ingredients are added: 5-10 parts sodium citrate, 9-12 parts sodium polyacrylate supported on diatomaceous earth, 12-15 parts magnesium oxide, and 50-75 parts PLA, with the specific mass percentages as follows: S21, the reinforced masterbatch is composed of sodium citrate, sodium polyacrylate supported on diatomaceous earth, magnesium oxide, and PLA, wherein sodium citrate is 6.9 parts, sodium polyacrylate supported on diatomaceous earth is 10.3 parts, magnesium oxide is 13.8 parts, and PLA is 69 parts.
[0027] It should be noted that 20-30 parts of reinforcing masterbatch are suitable for alkaline soils with a pH of 7-10, and 25 parts of reinforcing masterbatch are suitable for soils with a pH of 8.5. Furthermore, when the masterbatch content is 25 parts, the resulting plastic products... Performance verification is required. The verification data is shown in Tables 1 and 2 below. Performance Verification Table 1 Performance Verification Table 2 The following are the three data points for multi-pH environment adaptability verification; Multi-pH environment adaptability verification table 3 Degradation kinetics formula The value of k peaked at pH 8.5, confirming that 20–30 portions of masterbatch showed the highest efficiency in this range. The values represent the initial mass of the plastic before degradation and the time elapsed. Remaining mass after degradation, degradation rate constant, degradation time, and intercept The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing high-strength biodegradable plastic, characterized in that, The method includes the following steps: S1. Prepare the raw materials for plastic preparation. The raw materials consist of PBAT, PLA, nano calcium carbonate, zinc stearate, glycerides, magnesium oxide, sodium citrate, diatomaceous earth, sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide, hydrochloric acid, anhydrous ethanol, silane coupling agent KH560, molten stearic acid, and BHT antioxidant. The raw materials are then pretreated. S2. A reinforced masterbatch was prepared by using nano-magnesium oxide, sodium citrate and diatomaceous earth to support sodium polyacrylate. S3. Mix the ingredients made from the raw materials and blow mold them into a film.
2. The method for preparing high-strength biodegradable plastic according to claim 1, characterized in that, The raw materials for preparing the plastic are composed of PBAT, PLA, nano-calcium carbonate, zinc stearate, glycerides, magnesium oxide, sodium citrate, diatomaceous earth, sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide, hydrochloric acid, anhydrous ethanol, silane coupling agent KH560, molten stearic acid, and BHT antioxidant. The raw materials undergo pretreatment as follows: S11. Prepare raw materials: PBAT, PLA, nano calcium carbonate, zinc stearate, glycerides, magnesium oxide, sodium citrate, diatomaceous earth, sodium acrylate, ammonium persulfate, N,N-methylenebisacrylamide, hydrochloric acid, anhydrous ethanol, silane coupling agent KH560, molten stearic acid, BHT antioxidant. S12. The diatomaceous earth was acid-washed and purified to prepare a 10% hydrochloric acid solution. The diatomaceous earth was then immersed in the 10% hydrochloric acid solution, and the solid-liquid ratio was controlled at 1:
5. The mixture was mechanically stirred for 60 minutes to dissolve the metal impurities. The mixture was then repeatedly washed with water until it was neutral, and the pH of the filtrate was 7.0±0.
2. The mixture was then transferred to a 120℃ hot air drying oven for 6 hours and the moisture content was tested to be ≤0.5%. Finally, the mixture was pulverized to 80 mesh and sieved to control the particle size to be ≤180μm. S13. Prepare sodium polyacrylate supported on diatomaceous earth using acid-washed and purified diatomaceous earth. S14. Mix KH560 stock solution with anhydrous ethanol at a mass ratio of 1:9, and then add deionized water to prepare a silane coupling agent KH560 ethanol solution, wherein the deionized water accounts for 2% to 5% of the mass of KH560; S15. Take magnesium oxide powder with a particle size of 30-50 nm and place it in a vacuum drying oven at 60℃ for 4 hours to dehydrate. Mix it with silane coupling agent KH560 ethanol solution by wet method. The mass ratio of magnesium oxide to silane coupling agent KH560 ethanol solution is 100:
1. After drying at 80℃, put it into a planetary ball mill, set the speed to 300 rpm, and the ball milling time is 30 minutes. After the ball milling is completed, pass it through a 400-mesh sieve to obtain activated magnesium oxide. S16. The selected glycerides are epoxidized soybean oil with an epoxy value ≥6.
0. 0.1% BHT antioxidant is added to it. After filtration through a 10μm filter membrane, it is stored in the dark and the storage temperature is controlled below 25℃. S17. Spread PBAT and PLA granules in layers in a hot air circulating drying oven, set the temperature to 80℃ and treat for 8 hours. Turn the material over every 2 hours during the treatment. After treatment, use the Karl Fischer method to test the moisture content and ensure that the moisture content is ≤0.05%.
3. The method for preparing high-strength biodegradable plastic according to claim 1, characterized in that, The preparation of sodium polyacrylate supported on diatomaceous earth using acid-washed and purified diatomaceous earth includes the following steps: S131. Diatomaceous earth and sodium acrylate are added to the reactor in a mass ratio of 1:2, and ammonium persulfate and N,N-methylenebisacrylamide are added. The reactor is then evacuated to -0.08 MPa and heated to 60°C. The reaction is carried out for 120 minutes to generate hydrogel. S132. Wash the hydrogel three times with anhydrous ethanol, dry it under vacuum at 60°C for 12 hours, then pulverize it into 100-200μm particles and verify that the swelling rate is ≥300g / g.
4. The method for preparing high-strength biodegradable plastic according to claim 1, characterized in that, The preparation of reinforced masterbatch using sodium polyacrylate loaded with diatomite made from nano-magnesium oxide, sodium citrate, and diatomite includes the following steps: S21. Place magnesium oxide and sodium citrate into a three-dimensional motion mixer in a clean room with humidity ≤30%, add 0.5% fumed silica as an anti-caking agent, and mix at 25 rpm for 30 minutes to ensure uniform powder dispersion. S22. In zones 1-3 of the twin-screw extruder, premixed powder is added, and zinc stearate is added simultaneously. The screw speed is set to 100 rpm to form a preliminary melt mixture. PLA is injected into zones 4-6 of the twin-screw extruder to fully melt and coat the powder mixture, while controlling the melt viscosity at 3500-4000 mPa·s. Diatomaceous earth-loaded sodium polyacrylate composite particles are added to zones 7-9 of the twin-screw extruder. The shear speed is set to 150 rpm, and a -0.08 MPa vacuum devolatilization is started simultaneously for 2 minutes to remove moisture and volatiles, ensuring that the SAP activity retention rate is ≥95%. In zones 10-12, the heat-sensitive components are cooled and protected. The melt is extruded through a custom coat hanger die, with the cutter speed set to 300 rpm, the water temperature at 25±2℃, and an underwater pelletizing system is used to generate homogeneous masterbatch particles with a diameter of 3 mm and a length of 2 mm. S23. Set the speed to 2000 rpm for 5 minutes. Remove the surface moisture of the wet masterbatch by centrifugal dewatering machine and transfer it to a fluidized bed dryer. Set the fluidized bed dryer to 60℃ hot air and 2m / s for 2 hours to control the moisture content to ≤0.03%. Then, screen out irregularly shaped particles with a particle size <1mm or >4mm.
5. The method for preparing high-strength biodegradable plastic according to claim 1, characterized in that, The process involves mixing ingredients made from raw materials and then blow molding them into a film. S31. Accurately weigh PBAT, fortified masterbatch, nano calcium carbonate, epoxidized soybean oil, and zinc stearate. S32. Add solid materials including PBAT, reinforced masterbatch, and calcium carbonate into a high-speed mixer and premix at 800 rpm for 3 minutes. Then spray with epoxidized soybean oil and continue stirring for 2 minutes. S33. Transfer the mixture into a co-rotating twin-screw extruder, set the screw speed to 180 rpm, and then turn on the -0.06 MPa vacuum devolatilization; finally, the melt is filtered through a 200-mesh filter and then conveyed to the three-layer co-extrusion blown film die. S34 uses a stacked three-layer die blow molding process.
6. A high-strength biodegradable plastic, characterized in that, The plastic is a high-strength biodegradable plastic and its preparation method as described in any one of claims 1-5, specifically comprising the following components: S1, PBAT, 50-70 parts; reinforced masterbatch, 20-30 parts; activated nano calcium carbonate, 4-8 parts; epoxidized soybean oil, 4-8 parts; zinc stearate, 0.5-3 parts. S2, the reinforced masterbatch consists of sodium citrate, diatomaceous earth-supported sodium polyacrylate, magnesium oxide, and PLA, with sodium citrate comprising 5-10 parts, diatomaceous earth-supported sodium polyacrylate comprising 9-12 parts, magnesium oxide comprising 12-15 parts, and PLA comprising 50-75 parts.
7. A high-strength biodegradable plastic according to claim 6, characterized in that, The specific mass fractions of the PBAT (50-70 parts), fortified masterbatch (20-30 parts), activated nano-calcium carbonate (4-8 parts), epoxidized soybean oil (4-8 parts), and zinc stearate (0.5-3 parts) are as follows: S11, PBAT, 64 parts; reinforced masterbatch, 25 parts; activated nano calcium carbonate, 5 parts; epoxidized soybean oil, 5 parts; zinc stearate, 1 part.
8. A high-strength biodegradable plastic according to claim 6, characterized in that, The specific mass fractions of the following components are as follows: 5-10 parts sodium citrate, 9-12 parts sodium polyacrylate supported on diatomaceous earth, 12-15 parts magnesium oxide, and 50-75 parts PLA. S21, the reinforced masterbatch is composed of sodium citrate, sodium polyacrylate supported on diatomaceous earth, magnesium oxide, and PLA, wherein sodium citrate is 6.9 parts, sodium polyacrylate supported on diatomaceous earth is 10.3 parts, magnesium oxide is 13.8 parts, and PLA is 69 parts.