Bio-based degradable buffer composite material prepared on basis of waste gas column bag and preparation method of bio-based degradable buffer composite material

Abstract

The invention provides a bio-based degradable buffer composite material prepared on the basis of a waste gas column bag and a preparation method of the bio-based degradable buffer composite material. The composite material is prepared from the following raw materials in parts by weight: 35 to 45 parts of waste gas column bag reclaimed materials, 18 to 25 parts of polylactic acid, 12 to 18 parts of polymethyl ethylene carbonate, 8 to 12 parts of poly (butylene adipate-co-terephthalate), 2 to 4 parts of chitosan-based ternary grafting compatilizer, 3 to 6 parts of polycaprolactone coated modified hollow glass beads, 0.4 to 0.8 part of epoxy chain extender, 0.5 to 1.5 parts of polyolefin elastomer, 1 to 3 parts of epoxidized soybean oil, 0.5 to 1.2 parts of lubricant and 0.2 to 0.6 part of antioxidant. And 0.3 to 0.7 part of a heat stabilizer. According to the invention, resource utilization of the waste air column bag is realized, the cost is reduced, the material has excellent buffering, mechanical, barrier and processing properties, the toughness, rigidity and impact resistance are synergistically improved by all the components, and the material has good interfacial compatibility and excellent degradability.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, specifically to a bio-based biodegradable cushioning composite material prepared from waste air column bags and its preparation method. Background Technology

[0002] With the rapid development of the express delivery and logistics industry, air column bags have become widely used as a highly efficient cushioning packaging material. However, most of them are made of non-degradable materials such as polypropylene, resulting in a large number of discarded air column bags that are difficult to degrade naturally after use, creating "white pollution." Furthermore, the recycling rate of these discarded air column bags is low, leading to resource waste. Currently, the demand for biodegradable materials in the cushioning packaging field is increasingly urgent. Polyester biodegradable plastics, due to their good degradation properties, have become an important direction for replacing traditional non-degradable cushioning materials. However, single biodegradable resins suffer from problems such as an imbalance between rigidity and toughness, insufficient cushioning performance, and high raw material costs, making it difficult to meet the needs of actual packaging scenarios.

[0003] In existing technologies, although there have been attempts to prepare cushioning materials by combining waste plastic recycling materials with biodegradable resins to achieve waste resource utilization and reduce costs, the large polarity difference between waste air column bag recycling materials and biodegradable resins results in weak interfacial bonding and easy phase separation, leading to a significant reduction in the mechanical and cushioning properties of the composite materials. At the same time, most composite systems have not been synergistically optimized for cushioning and degradation performance, making it difficult to achieve excellent impact absorption performance, mechanical stability, and efficient biodegradability. Such composite systems are difficult to adapt to the actual industrial application requirements of cushioning packaging materials, limiting the recycling of waste air column bags and the industrial promotion of biodegradable cushioning materials. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a bio-based biodegradable cushioning composite material prepared from waste air column bags and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention discloses a bio-based biodegradable cushioning composite material prepared from waste air column bags. The raw materials for its preparation include: 35-45 parts of recycled waste air column bags, 18-25 parts of polylactic acid, 12-18 parts of polymethyl ethylene carbonate, 8-12 parts of polybutylene adipate-terephthalate, 2-4 parts of chitosan-based ternary graft compatibilizer, 3-6 parts of polycaprolactone-coated modified hollow glass microspheres, 0.4-0.8 parts of epoxy chain extender, 0.5-1.5 parts of polyolefin elastomer, 1-3 parts of epoxidized soybean oil, 0.5-1.2 parts of lubricant, 0.2-0.6 parts of antioxidant, and 0.3-0.7 parts of heat stabilizer.

[0007] Using the above technical solutions, the introduction of recycled waste gas column bags enables the resource-based recycling of waste gas column bags, reducing raw material costs and providing basic toughness and water resistance to the material. Polylactic acid provides rigid support for the material, while polymethyl ethylene carbonate possesses excellent toughness and gas barrier properties, and the carbonate bonds in its molecular chain are prone to hydrolysis. Polybutylene adipate-terephthalate can improve the material's flexibility and elongation at break. Chitosan-based ternary graft compatibilizers can effectively improve the interfacial bonding force between polar bio-based resins and non-polar recycled waste gas column bags, inhibiting phase separation in the system, and simultaneously possessing the dual effects of metal chelation and degradation promotion. Polycaprolactone-coated modified hollow glass microspheres can disperse stress and absorb impact energy through the synergistic effect of the hollow structure and polymer coating, improving the material's buffering performance and reducing its density. After the polycaprolactone coating undergoes biodegradation, the pores generated by its degradation are interconnected with the original pores of the hollow glass microspheres, providing a habitat for microorganisms. The adhesion and water penetration provide an effective mass transfer pathway, accelerating the overall biodegradation of the composite material; epoxy chain extenders can play a chain-extending role during the material's melt processing, coupling and lengthening polyester molecular chains, improving melt strength and material mechanical properties; polyolefin elastomers can compensate for matrix brittleness, improving the material's impact resistance and elongation at break; epoxidized soybean oil can improve the material's processing fluidity and flexibility, and the epoxy groups on its molecular chains can undergo ring-opening addition reactions with acidic catalytic small molecules generated by polyester degradation in the system, effectively quenching the acidic catalytic small molecules in the system, inhibiting their autocatalytic hydrolysis of polyester molecular chains, and thus maintaining the chemical stability of the system; lubricants can reduce the friction between the melt and equipment during processing, ensuring the smooth implementation of the molding process; antioxidants can inhibit the thermo-oxidative aging of materials during high-temperature processing; heat stabilizers can specifically inhibit the depolymerization and thermal degradation behavior of polymethyl ethylene carbonate during high-temperature processing, maintaining the performance stability of the melt and the final product.

[0008] Preferably, the lubricant is one of calcium stearate or erucamide; the antioxidant is a compound of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1 to 1:2; and the heat stabilizer is a compound of triphenyl phosphite and zinc stearate in a mass ratio of 1:1 to 2:1.

[0009] Using the above technical solutions, calcium stearate or erucamide can effectively reduce the frictional resistance between the melt and the metal wall of the processing equipment during the composite material melting process, ensuring the continuous and stable progress of the composite material molding process; the antioxidant 1010 and antioxidant 168 compounded in a mass ratio of 1:1 to 1:2 can inhibit the thermo-oxidative aging of the composite material during high-temperature processing, taking into account both the inhibitory effect on the oxidative breakage of polyester molecular chain segments and the decomposition effect of peroxides in the system; the heat stabilizer compounded in a mass ratio of 1:1 to 2:1 of triphenyl phosphite and zinc stearate can specifically inhibit the depolymerization and thermal degradation behavior of polymethyl ethylene carbonate during high-temperature processing, and simultaneously maintain the stability of melt performance and final product performance.

[0010] Preferably, the raw materials for preparing the chitosan-based ternary graft compatibilizer, by weight, include: 4-6 parts chitosan, 2-4 parts anhydrous citric acid, 1-2 parts dopamine derivative, 0.5-0.7 parts 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.2-0.4 parts N-hydroxysuccinimide, and 0.1-0.3 parts processing stabilizer; the dopamine derivative is prepared by transesterification of dopamine hydrochloride and glyceryl monostearate in a molar ratio of 1:1.2-1:1.5; the processing stabilizer is prepared by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1-1:2.

[0011] Using the above technical solution, the synergistic effect of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide can improve the grafting efficiency of anhydrous citric acid and chitosan. The dopamine derivative can effectively participate in the grafting reaction and improve the high-temperature stability of the compatibilizer. The dopamine derivative prepared by transesterification of dopamine hydrochloride and glyceryl monostearate in a molar ratio of 1:1.2 to 1:1.5 can meet the functional group matching requirements of the grafting reaction and synergistically optimize the interfacial compatibility and high-temperature stability of the compatibilizer. The processing stabilizer, which is a compound of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1 to 1:2, can effectively protect the dopamine derivative during the grafting reaction, prevent its oxidative degradation, and ensure the grafting rate and product performance stability of the chitosan-based ternary graft compatibilizer.

[0012] Preferably, the preparation method of the chitosan-based ternary graft compatibilizer includes the following steps:

[0013] 1) Disperse chitosan in an aqueous acetic acid solution with a volume fraction of 0.8-1.2%, the amount of which is 40-50 times the mass of the chitosan. Stir at 300-500 r / min at 20-30℃ for 30-60 min until completely dissolved.

[0014] 2) Add anhydrous citric acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide to the solution obtained in step 1). Stir the mixture at 200-400 r / min for 16-20 h at 25-30 °C. Pour the reaction solution into excess acetone to precipitate the precipitate. After filtration, wash the precipitate with ethanol 2-4 times and then vacuum dry it to constant weight at 38-42 °C and a gauge pressure of -0.08-0.09 MPa to obtain anhydrous citric acid grafted chitosan.

[0015] 3) Dissolve anhydrous citric acid-grafted chitosan in 2-morpholine ethanesulfonic acid buffer, the amount of 2-morpholine ethanesulfonic acid buffer being 35 to 45 times the mass of anhydrous citric acid-grafted chitosan. Then add a processing stabilizer and activate the mixture by stirring at 300 to 500 r / min at 20 to 30°C for 25 to 30 minutes. Subsequently, add a dopamine derivative and continue stirring for 18 to 24 hours.

[0016] 4) Centrifuge the reaction solution obtained in step 3) at a speed of 9000~10000 r / min for 10~20 min, discard the supernatant, redisperse the precipitate with deionized water and centrifuge again. Repeat this centrifugation and washing process 3~5 times, and then vacuum dry it to constant weight at 50~60℃ and gauge pressure of -0.08~-0.09 MPa to obtain chitosan-based ternary graft compatibilizer.

[0017] Using the above technical solution, the grafting of chitosan with anhydrous citric acid and dopamine derivatives is achieved through a stepwise reaction. Acetic acid aqueous solution fully dissolves chitosan, providing a homogeneous system for subsequent grafting reactions. The combination of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide promotes the smooth progress of the grafting reaction between anhydrous citric acid and chitosan. Acetone precipitation and ethanol washing purify the anhydrous citric acid-grafted chitosan. 2-morpholine ethanesulfonic acid buffer dissolves the anhydrous citric acid-grafted chitosan, and the processing stabilizer protects the dopamine derivative, ensuring the grafting reaction effect with the anhydrous citric acid-grafted chitosan. Centrifugal washing removes impurities and unreacted monomers from the reaction solution, and vacuum drying removes moisture from the product, ultimately yielding a chitosan-based ternary graft compatibilizer.

[0018] Preferably, the preparation method of the dopamine derivative is as follows: dopamine hydrochloride and glyceryl monostearate are added to anhydrous toluene at a molar ratio of 1:1.2 to 1:1.5, and 0.5 to 1.0% by mass of p-toluenesulfonic acid is added. The mixture is refluxed under vacuum at 80 to 90°C and a gauge pressure of -0.095 MPa for 4 to 5 hours. After the solvent is removed by vacuum distillation, the reaction solution is purified by recrystallization from ethanol to obtain a dopamine derivative with a purity ≥98%.

[0019] Using the above technical solution, anhydrous toluene is used as the reaction medium for the preparation of dopamine derivatives. Toluenesulfonic acid can promote the smooth reaction of dopamine hydrochloride and glyceryl monostearate. Vacuum reflux can remove the water generated in the reaction and promote the forward reaction. Vacuum distillation can remove the anhydrous toluene solvent in the reaction solution, and ethanol recrystallization can purify the product, finally obtaining a dopamine derivative with a purity of not less than 98%, ensuring the effectiveness of its subsequent grafting reaction with chitosan and anhydrous citric acid.

[0020] Preferably, the raw materials for preparing the polycaprolactone-coated modified hollow glass microspheres, by weight, include: 9-11 parts of hollow glass microspheres, 0.8-1.2 parts of 3-aminopropyltriethoxysilane, 0.4-0.6 parts of 3-hydroxypropyltrimethoxysilane, 18-22 parts of ε-caprolactone, 0.04-0.06 parts of stannous octoate, and 90-110 parts of toluene.

[0021] Using the above technical solution, hollow glass microspheres serve as the substrate, providing the basic framework for polycaprolactone-coated modified hollow glass microspheres. 3-Aminopropyltriethoxysilane and 3-hydroxypropyltrimethoxysilane synergistically couple and modify the surface of the hollow glass microspheres, introducing amino and hydroxyl bifunctional groups onto their surface. This facilitates subsequent chemical bonding with the end groups of polycaprolactone, thereby enhancing the interfacial bonding force between the microspheres and the polycaprolactone coating layer. ε-caprolactone, as the coating material, forms a polycaprolactone layer coating the surface of the microspheres after the reaction. Stannous octoate promotes the smooth polymerization reaction of ε-caprolactone. Toluene, as the reaction medium, provides a suitable system environment for the uniform dispersion of each raw material and subsequent reactions. The synergistic effect of each raw material ensures the successful preparation of polycaprolactone-coated modified hollow glass microspheres.

[0022] Preferably, the preparation method of the polycaprolactone-coated modified hollow glass microspheres includes the following steps:

[0023] (1) Vacuum dry the hollow glass microspheres at 118~122℃ and -0.08~-0.09MPa for 5~7h;

[0024] (2) Take 40-50% of the total weight of toluene and add dried hollow glass microspheres. Disperse them for 10-20 min under ultrasonic power of 200-400 W and frequency of 20-40 kHz. Add 3-aminopropyltriethoxysilane and 3-hydroxypropyltrimethoxysilane dropwise at a rate of 2-4 mL / min. After all the dropwise addition is completed, stir the reaction at 200-400 r / min for 3-5 h under conditions of 78-82 °C and gauge pressure of -0.02-0.03 MPa. After washing the product with toluene 2-3 times, vacuum dry it to constant weight under conditions of 98-102 °C and gauge pressure of -0.08-0.09 MPa to obtain amino-hydroxy bifunctional modified hollow glass microspheres.

[0025] (3) Add the amino-hydroxy bifunctional modified hollow glass microspheres to the remaining toluene, disperse them under ultrasonic power of 200~400W and frequency of 20~40kHz for 25~35min, add ε-caprolactone and stannous octoate, and react for 8~12h under nitrogen protection, reflux at 110~120℃ and 200~400r / min.

[0026] (4) Cool the reaction solution obtained in step (3) to 20~30℃, filter it, wash it with n-hexane 2~4 times, and vacuum dry it at 48~52℃ and gauge pressure -0.08~-0.09MPa for 20~28h to obtain polycaprolactone-coated modified hollow glass microspheres.

[0027] Using the above technical solution, the hollow glass microspheres are first vacuum dried to remove adsorbed water and avoid moisture affecting subsequent reactions. Then, the hollow glass microspheres are uniformly dispersed in toluene by ultrasonic dispersion. Silane reagents are added dropwise, and the mixture is stirred, washed, and dried to achieve amino-hydroxyl bifunctional modification of the microsphere surface. Subsequently, the modified microspheres are dispersed in the remaining toluene, and ε-caprolactone and stannous octoate are added. The mixture is then refluxed under nitrogen protection to polymerize ε-caprolactone to form a polycaprolactone layer coating the microsphere surface. Finally, after cooling, filtration, washing, and vacuum drying, polycaprolactone-coated modified hollow glass microspheres are obtained.

[0028] Preferably, the polylactic acid has a weight-average molecular weight of 9 × 10⁻⁶. 4 ~11×10 4 Da, the weight-average molecular weight of the polymethyl ethylene carbonate is 8 × 10⁻⁶. 4 ~12×10 4 Da, the weight-average molecular weight of the polybutylene adipate terephthalate is 15 × 10⁻⁶. 4 ~20×10 4 Da, the weight-average molecular weight of the polyolefin elastomer is 20 × 10⁻⁶. 4 ~30×10 4 Da.

[0029] By adopting the above technical solution, the weight-average molecular weights of polylactic acid, polymethyl ethylene carbonate, polybutylene adipate terephthalate, and polyolefin elastomer are controlled within the corresponding ranges. This ensures the stability of the molecular structure of each resin component, allowing the rigid support of polylactic acid, the toughness and gas barrier properties of polymethyl ethylene carbonate, and the flexibility of polybutylene adipate terephthalate to be fully utilized. Simultaneously, it enhances the melt blendability between components, ensuring uniform dispersion during high-temperature processing, inhibiting phase separation, and balancing the mechanical properties and processing flowability of the composite material. The aforementioned molecular weight range of the polyolefin elastomer effectively compensates for the brittleness of the composite matrix, working synergistically with other components to maintain the stability of the composite material's overall performance.

[0030] This invention also discloses a method for preparing a bio-based biodegradable cushioning composite material based on waste air column bags, comprising the following steps:

[0031] S1. Raw material pretreatment: Weigh polylactic acid, polymethyl ethylene carbonate, polybutylene adipate terephthalate, polyolefin elastomer, and recycled waste air column bags according to the proportions, and vacuum dry them at 78~82℃ and -0.08~-0.09MPa for 4~6 hours until the moisture content is ≤0.05%;

[0032] S2. Premixing: The raw materials pretreated in step S1, chitosan-based ternary graft compatibilizer, polycaprolactone-coated modified hollow glass microspheres, epoxy chain extender, epoxidized soybean oil, lubricant, antioxidant and heat stabilizer are added to a high-speed mixer and stirred at 600-800 r / min at 20-30℃ for 8-12 minutes to obtain a premix.

[0033] S3. Melt extrusion granulation: The premix obtained in step S2 is added to a co-rotating twin-screw extruder. The temperature of each zone is controlled as follows: feeding section 165~170℃, conveying section 180~185℃, melting section 170~175℃, homogenization section 170~175℃, and die head section 165~170℃. The screw speed is 250~350 r / min, and the vacuum degree of the vacuum exhaust port is -0.08~-0.09 MPa. After melt blending, extrusion, cooling, water cooling, and pelletizing, composite material masterbatch is obtained.

[0034] S4. Molding: The composite material masterbatch obtained in step S3 is vacuum dried at 75~85℃ and gauge pressure of -0.08~-0.09MPa for 3~5h, then added to an injection molding machine and molded under the conditions of barrel temperature of 175~190℃, mold temperature of 25~40℃, injection pressure of 60~85MPa, holding pressure of 40~60MPa, holding time of 15~30s, and cooling time of 25~40s to obtain a bio-based biodegradable cushioning composite material.

[0035] Using the above technical solutions, raw material pretreatment can remove moisture from each component, preventing moisture from affecting the structural integrity and performance stability of the composite material in subsequent processing; premixing can ensure that all raw materials are uniformly dispersed, reducing phase separation between components and laying the foundation for subsequent melt blending; melt extrusion granulation, by controlling the appropriate temperature and screw speed in each zone, achieves full melt blending of each component, improves melt processing performance, and ensures the quality uniformity of the obtained masterbatch; matching the process parameters of the molding step with the characteristics of the masterbatch can ensure good molding effect of the composite material, ensuring that it ultimately possesses excellent mechanical properties, cushioning properties, and biodegradability. The synergistic effect of each step ensures the stability of the preparation process and the uniformity of product quality.

[0036] Preferably, the waste gas column bag recycled material is sorted, crushed, alkali washed, water washed, and dried, and then melt-extruded and granulated by a single screw extruder. The alkali washing uses a sodium hydroxide solution with a mass fraction of 0.8~1.2% and is carried out at 55~65℃ for 10~20 minutes.

[0037] Using the above technical solutions, sorting and crushing can remove impurities and process them into a form suitable for subsequent processing; alkaline washing can effectively remove oil, stains and residual impurities from the surface of the recycled material, while the water washing process can thoroughly remove the residual sodium hydroxide solution on the surface of the particles, avoiding the adverse effects of residual alkali and impurities on the subsequent melting process and the performance of the final composite material; drying can remove moisture from the recycled material, and after melt extrusion granulation, the recycled material from the waste air column bag can be formed into granules with uniform particle size, which facilitates the subsequent mixing operation with other raw materials, thereby ensuring that the components of the composite material are uniformly dispersed during the melt blending process, while improving processing convenience and stability.

[0038] The beneficial effects of this invention are as follows:

[0039] The introduction of recycled waste gas column bags enables the resource-based recycling of these bags, reducing raw material costs and providing basic toughness and water resistance. Polylactic acid provides rigid support, while polymethyl ethylene carbonate possesses excellent toughness and gas barrier properties, and its carbonate bonds are prone to hydrolysis. Polybutylene adipate-terephthalate (PAT) enhances the material's flexibility and elongation at break. Chitosan-based ternary graft compatibilizers effectively improve the interfacial bonding between polar bio-based resins and non-polar recycled waste gas column bags, inhibiting phase separation and exhibiting both metal chelation and degradation-promoting effects. Polycaprolactone-coated modified hollow glass microspheres can disperse stress and absorb impact energy through the synergistic effect of the hollow structure and polymer coating, improving the material's buffering performance and reducing its density. After the polycaprolactone coating undergoes biodegradation, the resulting pores connect with the original pores of the hollow glass microspheres, facilitating microbial attachment and water absorption. The penetration of components provides an effective mass transfer pathway, accelerating the overall biodegradation of the composite material; epoxy chain extenders can play a chain-extending role during the material's melt processing, coupling and lengthening polyester molecular chains, improving melt strength and material mechanical properties; polyolefin elastomers can compensate for matrix brittleness, improving the material's impact resistance and elongation at break; epoxidized soybean oil can improve the material's processing fluidity and flexibility, and the epoxy groups on its molecular chains can undergo ring-opening addition reactions with acidic catalytic small molecules generated by polyester degradation in the system, effectively quenching the acidic catalytic small molecules in the system, inhibiting their autocatalytic hydrolysis of polyester molecular chains, and thus maintaining the chemical stability of the system; lubricants can reduce friction between the melt and equipment during processing, ensuring smooth implementation of the molding process; antioxidants can inhibit thermo-oxidative aging during high-temperature processing of the material; heat stabilizers can specifically inhibit the depolymerization and thermal degradation behavior of polymethyl ethylene carbonate during high-temperature processing, maintaining the performance stability of the melt and the final product. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] The specific information on the raw materials used in the embodiments of the present invention is shown in Table 1.

[0042] Table 1

[0043] Components Specification source Waste air column bag recycling material / discarded polypropylene air column bags from e-commerce logistics Polylactic acid <![CDATA[The weight-average molecular weight is 9×10 4 ~11×10 4 Da]]> Zhejiang Hisun Biomaterials Co., Ltd. polymethyl ethylene carbonate <![CDATA[The weight-average molecular weight is 8×10 4 ~12×10 4 Da]]> Dongguan Haopinfa Plastic Raw Materials Co., Ltd. Poly(butylene adipate) terephthalate <![CDATA[The weight-average molecular weight is 15×10 4 ~20×10 4 Da]]> Dongguan Kadar Plastic Raw Materials Co., Ltd. Chitosan Deacetylation degree ≥90%, viscosity 100-200 mPa·s Shanghai Aladdin Biochemical Technology Co., Ltd. Anhydrous citric acid 99% purity, CAS: 77-92-9 Wuhan Jiyesheng Chemical Co., Ltd. Dopamine hydrochloride 99% purity, CAS: 62-31-7 Shanghai Yuyuan Biochemical Co., Ltd. Glyceryl monostearate 99% purity, CAS: 123-94-4 Nantong Chenrun Chemical Co., Ltd. 1-Ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride 99% purity, CAS: 25952-53-8 Shanghai Covalent Chemical Technology Co., Ltd. N-hydroxysuccinimide 99% purity, CAS: 6066-82-6 Shanghai Kanglang Biotechnology Co., Ltd. Antioxidant 1010 99% purity BASF (China) Co., Ltd. Antioxidant 168 99% purity BASF (China) Co., Ltd. Hollow glass microspheres <![CDATA[Average particle size 30μm, true density 0.3g / cm 3 > 3M China Co., Ltd. 3-Aminopropyltriethoxysilane 99% purity Nanjing Shuguang Chemical Group 3-Hydroxypropyltrimethoxysilane 99% purity Nanjing Shuguang Chemical Group ε-caprolactone 99% purity, CAS: 502-44-3 Shanghai Baishun Biotechnology Co., Ltd. Stannous octoate Purity 99%, CAS: 301-10-0 Wuhan Jushun Chemical Co., Ltd. Toluene Analytical Pure Sinopharm Chemical Reagent Co., Ltd. Epoxy chain extender Joncryl® ADR-4468 BASF (China) Co., Ltd. Polyolefin elastomers <![CDATA[The weight-average molecular weight is 20×10 4 ~30×10 4 Da]]> Dow Chemical Engage™ 8150 Epoxidized soybean oil Epoxy value ≥6.0%, CAS: 8013-07-8 Shandong Xinheng Chemical Co., Ltd. Calcium stearate food grade Hangzhou Oil & Chemical Co., Ltd. Erucamide 99% purity, CAS: 112-84-5 Hubei Chengfeng Chemical Co., Ltd. Triphenyl phosphite Purity 99%, CAS: 101-02-0 Nantong Runfeng Petrochemical Co., Ltd. Zinc stearate 99% purity Hubei Chengfeng Chemical Co., Ltd. 2-Morpholine ethanesulfonic acid buffer 0.1M, pH 5.5 Hubei Weishi Chemical Reagent Co., Ltd.

[0044] Example 1:

[0045] This embodiment discloses a bio-based biodegradable cushioning composite material prepared from waste air column bags. The raw materials for its preparation include: 35 parts of recycled waste air column bag material with a weight-average molecular weight of 9 × 10⁻⁶. 4 18 parts of polylactic acid (D) with a weight-average molecular weight of 8 × 10⁻⁶ 4 12 parts of Da's polymethyl ethylene carbonate, with a weight-average molecular weight of 15 × 10⁻⁶. 4 The composition of Da consists of 8 parts poly(butylene adipate-terephthalate), 2 parts chitosan-based ternary graft compatibilizer, 3 parts polycaprolactone-coated modified hollow glass microspheres, and 0.4 parts epoxy chain extender, with a weight-average molecular weight of 20 × 10⁻⁶. 4 The composition includes 0.5 parts of polyolefin elastomer, 1 part of epoxidized soybean oil, 0.5 parts of calcium stearate, 0.2 parts of antioxidant, and 0.3 parts of heat stabilizer. Waste gas column bag recycled material is sorted, crushed, alkali-washed, water-washed, and dried, then melt-extruded and granulated using a single-screw extruder. The alkali washing uses a 0.8% sodium hydroxide solution at 55°C for 10 minutes. The antioxidant is a 1:1 mass ratio blend of antioxidant 1010 and antioxidant 168; the heat stabilizer is a 1:1 mass ratio blend of triphenyl phosphite and zinc stearate.

[0046] The raw materials for preparing the chitosan-based ternary graft compatibilizer, by weight, include: 4 parts chitosan, 2 parts anhydrous citric acid, 1 part dopamine derivative, 0.5 parts 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.2 parts N-hydroxysuccinimide, and 0.1 parts processing stabilizer; the dopamine derivative is prepared by transesterification of dopamine hydrochloride and glyceryl monostearate in a molar ratio of 1:1.2; the processing stabilizer is prepared by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.

[0047] The preparation method of dopamine derivative is as follows: dopamine hydrochloride and glyceryl monostearate are added to anhydrous toluene at a molar ratio of 1:1.2, and 0.5% p-toluenesulfonic acid is added. The mixture is refluxed under vacuum at 80℃ and a gauge pressure of -0.095MPa for 4 hours. After removing the solvent by vacuum distillation, the reaction solution is purified by recrystallization from ethanol to obtain dopamine derivative with a purity ≥98%.

[0048] The preparation method of chitosan-based ternary graft compatibilizer includes the following steps:

[0049] 1) Disperse chitosan in an aqueous solution of acetic acid with a volume fraction of 0.8%, the amount of acetic acid being 40 times the mass of chitosan, and stir at 300 r / min at 20℃ for 30 min until completely dissolved;

[0050] 2) Add anhydrous citric acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide to the solution obtained in step 1). Stir the mixture at 200 r / min for 16 h at 25 °C. Pour the reaction solution into excess acetone to precipitate the precipitate. After filtration, wash the precipitate twice with ethanol and then vacuum dry it to constant weight at 38 °C and a gauge pressure of -0.08 MPa to obtain anhydrous citric acid grafted chitosan.

[0051] 3) Dissolve anhydrous citric acid-grafted chitosan in 2-morpholine ethanesulfonic acid buffer, the amount of 2-morpholine ethanesulfonic acid buffer being 35 times the mass of anhydrous citric acid-grafted chitosan. Then add a processing stabilizer and activate the mixture by stirring at 300 r / min at 20°C for 25 min. Subsequently, add a dopamine derivative and continue stirring for 18 h.

[0052] 4) Centrifuge the reaction solution obtained in step 3) at 9000 r / min for 10 min, discard the supernatant, redisperse the precipitate with deionized water and centrifuge again. Repeat the centrifugation and washing process 3 times, and then vacuum dry to constant weight at 50℃ and gauge pressure -0.08 MPa to obtain chitosan-based ternary graft compatibilizer.

[0053] The raw materials for preparing polycaprolactone-coated modified hollow glass microspheres, by weight, include: 9 parts hollow glass microspheres, 0.8 parts 3-aminopropyltriethoxysilane, 0.4 parts 3-hydroxypropyltrimethoxysilane, 18 parts ε-caprolactone, 0.04 parts stannous octoate, and 90 parts toluene.

[0054] The preparation method of polycaprolactone-coated modified hollow glass microspheres includes the following steps:

[0055] (1) The hollow glass microspheres were vacuum dried at 118℃ and -0.08MPa for 5h;

[0056] (2) Take 40% of the total weight of toluene and add the dried hollow glass microspheres. Disperse them for 10 min under ultrasonic power of 200 W and frequency of 20 kHz. Add 3-aminopropyltriethoxysilane and 3-hydroxypropyltrimethoxysilane dropwise at a rate of 2 mL / min. After all the dropwise addition is completed, stir the reaction at 200 r / min for 3 h under the conditions of 78 °C and gauge pressure of -0.02 MPa. After washing the product twice with toluene, vacuum dry it to constant weight under the conditions of 98 °C and gauge pressure of -0.08 MPa to obtain amino-hydroxy bifunctional modified hollow glass microspheres.

[0057] (3) Add the amino-hydroxy bifunctional modified hollow glass microspheres to the remaining toluene, disperse for 25 min under ultrasonic power of 200 W and frequency of 20 kHz, add ε-caprolactone and stannous octoate, and react for 8 h under nitrogen protection, reflux at 110 °C and 200 r / min.

[0058] (4) Cool the reaction solution obtained in step (3) to 20°C, filter it, wash it twice with n-hexane, and vacuum dry it for 20 h at 48°C and gauge pressure -0.08 MPa to obtain polycaprolactone-coated modified hollow glass microspheres.

[0059] This embodiment also discloses a method for preparing a bio-based biodegradable cushioning composite material based on waste air column bags, including the following steps:

[0060] S1. Raw material pretreatment: Weigh polylactic acid, polymethyl ethylene carbonate, polybutylene adipate terephthalate, polyolefin elastomer, and recycled waste air column bags according to the proportions, and vacuum dry them at 78℃ and -0.08MPa for 4 hours until the moisture content is ≤0.05%;

[0061] S2. Premixing: The raw materials pretreated in step S1, chitosan-based ternary graft compatibilizer, polycaprolactone-coated modified hollow glass microspheres, epoxy chain extender, epoxidized soybean oil, calcium stearate, antioxidant and heat stabilizer are added to a high-speed mixer and stirred at 600 r / min for 8 min at 20°C to obtain a premix.

[0062] S3. Melt extrusion granulation: The premix obtained in step S2 is added to a co-rotating twin-screw extruder. The temperature of each zone is controlled as follows: feeding section 165℃, conveying section 180℃, melting section 170℃, homogenization section 170℃, and die head section 165℃. The screw speed is 250 r / min, and the vacuum degree of the vacuum exhaust port is gauge pressure -0.08 MPa. After melt blending, extrusion, cooling, water cooling, and pelletizing, composite material masterbatch is obtained.

[0063] S4. Molding: The composite material masterbatch obtained in step S3 is vacuum dried at 75℃ and gauge pressure of -0.08MPa for 3 hours, then added to an injection molding machine and molded under the conditions of barrel temperature of 175℃, mold temperature of 25℃, injection pressure of 60MPa, holding pressure of 40MPa, holding time of 15s, and cooling time of 25s to obtain a bio-based biodegradable cushioning composite material.

[0064] Example 2:

[0065] This embodiment discloses a bio-based biodegradable cushioning composite material prepared from waste air column bags. The raw materials for its preparation include: 45 parts of recycled waste air column bag material with a weight-average molecular weight of 11 × 10⁻⁶. 425 parts of polylactic acid (D) with a weight-average molecular weight of 12 × 10⁻⁵ 4 18 parts of Da's polymethyl ethylene carbonate, with a weight-average molecular weight of 20 × 10⁻⁶. 4 The composition of Da is as follows: 12 parts poly(butylene adipate-terephthalate), 4 parts chitosan-based ternary graft compatibilizer, 6 parts polycaprolactone-coated modified hollow glass microspheres, 0.8 parts epoxy chain extender, with a weight average molecular weight of 30 × 10⁻⁶. 4 The composition includes 1.5 parts of polyolefin elastomer, 3 parts of epoxidized soybean oil, 1.2 parts of erucamide, 0.6 parts of antioxidant, and 0.7 parts of heat stabilizer. Waste gas column bag recycled material is sorted, crushed, alkali-washed, water-washed, and dried, then melt-extruded and granulated using a single-screw extruder. The alkali washing uses a 1.2% sodium hydroxide solution at 65°C for 20 minutes. The antioxidant is a blend of antioxidant 1010 and antioxidant 168 in a 1:2 mass ratio; the heat stabilizer is a blend of triphenyl phosphite and zinc stearate in a 2:1 mass ratio.

[0066] The raw materials for preparing the chitosan-based ternary graft compatibilizer, by weight, include: 6 parts chitosan, 4 parts anhydrous citric acid, 2 parts dopamine derivative, 0.7 parts 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.4 parts N-hydroxysuccinimide, and 0.3 parts processing stabilizer; the dopamine derivative is prepared by transesterification of dopamine hydrochloride and glyceryl monostearate in a molar ratio of 1:1.5; the processing stabilizer is prepared by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2.

[0067] The preparation method of dopamine derivative is as follows: dopamine hydrochloride and glyceryl monostearate are added to anhydrous toluene at a molar ratio of 1:1.5, and p-toluenesulfonic acid with a mass fraction of 1.0% is added. The mixture is refluxed under vacuum at 90℃ and a gauge pressure of -0.095MPa for 5 hours. After removing the solvent by vacuum distillation, the reaction solution is purified by recrystallization from ethanol to obtain dopamine derivative with a purity ≥98%.

[0068] The preparation method of chitosan-based ternary graft compatibilizer includes the following steps:

[0069] 1) Disperse chitosan in an aqueous solution of acetic acid with a volume fraction of 1.2%, the amount of acetic acid being 50 times the mass of chitosan, and stir at 500 r / min at 30℃ for 60 min until completely dissolved;

[0070] 2) Add anhydrous citric acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide to the solution obtained in step 1). Stir the mixture at 30°C and 400 r / min for 20 h. Pour the reaction solution into excess acetone to precipitate the precipitate. After filtration, wash the precipitate four times with ethanol and then vacuum dry it to constant weight at 42°C and a gauge pressure of -0.09 MPa to obtain anhydrous citric acid grafted chitosan.

[0071] 3) Dissolve anhydrous citric acid-grafted chitosan in 2-morpholine ethanesulfonic acid buffer, the amount of 2-morpholine ethanesulfonic acid buffer being 45 times the mass of anhydrous citric acid-grafted chitosan. Then add a processing stabilizer and stir at 500 r / min at 30°C for 30 min to activate. Then add a dopamine derivative and continue stirring for 24 h.

[0072] 4) Centrifuge the reaction solution obtained in step 3) at 10000 r / min for 20 min, discard the supernatant, redisperse the precipitate with deionized water and centrifuge again. Repeat the centrifugation and washing process 5 times, and then vacuum dry to constant weight at 60℃ and gauge pressure -0.09 MPa to obtain chitosan-based ternary graft compatibilizer.

[0073] The raw materials for preparing polycaprolactone-coated modified hollow glass microspheres, by weight, include: 11 parts hollow glass microspheres, 1.2 parts 3-aminopropyltriethoxysilane, 0.6 parts 3-hydroxypropyltrimethoxysilane, 22 parts ε-caprolactone, 0.06 parts stannous octoate, and 110 parts toluene.

[0074] The preparation method of polycaprolactone-coated modified hollow glass microspheres includes the following steps:

[0075] (1) The hollow glass microspheres were vacuum dried at 122℃ and -0.09MPa for 7h;

[0076] (2) Take 50% of the total weight of toluene and add the dried hollow glass microspheres. Disperse them for 20 min under ultrasonic power of 400 W and frequency of 40 kHz. Add 3-aminopropyltriethoxysilane and 3-hydroxypropyltrimethoxysilane dropwise at a rate of 4 mL / min. After all the dropwise addition is completed, stir the reaction at 400 r / min for 5 h under the conditions of 82 °C and gauge pressure of -0.03 MPa. After washing the product with toluene 3 times, vacuum dry it to constant weight under the conditions of 102 °C and gauge pressure of -0.09 MPa to obtain amino-hydroxy bifunctional modified hollow glass microspheres.

[0077] (3) Add the amino-hydroxy bifunctional modified hollow glass microspheres to the remaining toluene, disperse them for 35 min under ultrasonic power of 400 W and frequency of 40 kHz, add ε-caprolactone and stannous octoate, and react for 12 h under nitrogen protection, reflux at 120 °C and 400 r / min.

[0078] (4) Cool the reaction solution obtained in step (3) to 30°C, filter it, wash it 4 times with n-hexane, and vacuum dry it for 28 hours at 52°C and gauge pressure -0.09MPa to obtain polycaprolactone-coated modified hollow glass microspheres.

[0079] This embodiment also discloses a method for preparing a bio-based biodegradable cushioning composite material based on waste air column bags, including the following steps:

[0080] S1. Raw material pretreatment: Weigh polylactic acid, polymethyl ethylene carbonate, polybutylene adipate terephthalate, polyolefin elastomer, and recycled waste air column bags according to the proportions, and vacuum dry them at 82℃ and -0.09MPa for 6 hours until the moisture content is ≤0.05%;

[0081] S2. Premixing: The raw materials pretreated in step S1, chitosan-based ternary graft compatibilizer, polycaprolactone-coated modified hollow glass microspheres, epoxy chain extender, epoxidized soybean oil, erucamide, antioxidant and heat stabilizer are added to a high-speed mixer and stirred at 800 r / min for 12 min at 30°C to obtain a premix.

[0082] S3. Melt extrusion granulation: The premix obtained in step S2 is added to a co-rotating twin-screw extruder. The temperature of each zone is controlled as follows: feeding section 170℃, conveying section 185℃, melting section 175℃, homogenization section 175℃, and die head section 170℃. The screw speed is 350 r / min, and the vacuum degree of the vacuum exhaust port is gauge pressure -0.09 MPa. After melt blending, extrusion, cooling, water cooling, and pelletizing, composite material masterbatch is obtained.

[0083] S4. Molding: The composite material masterbatch obtained in step S3 is vacuum dried for 5 hours at 85°C and gauge pressure of -0.09MPa. Then, it is added to an injection molding machine and molded under the conditions of barrel temperature of 190°C, mold temperature of 40°C, injection pressure of 85MPa, holding pressure of 60MPa, holding time of 30s, and cooling time of 40s to obtain a bio-based biodegradable cushioning composite material.

[0084] Example 3:

[0085] This embodiment discloses a bio-based biodegradable cushioning composite material prepared from waste air column bags. The raw materials for its preparation include: 40 parts of recycled waste air column bag material with a weight-average molecular weight of 10 × 10⁻⁶. 421 parts of polylactic acid (D) with a weight-average molecular weight of 10 × 10⁻⁶. 4 15 parts of Da's polymethyl ethylene carbonate, with a weight-average molecular weight of 17 × 10⁻⁶. 4 The composition of Da is as follows: 10 parts poly(butylene adipate-terephthalate), 3 parts chitosan-based ternary graft compatibilizer, 4.5 parts polycaprolactone-coated modified hollow glass microspheres, 0.6 parts epoxy chain extender, with a weight average molecular weight of 25 × 10⁻⁶. 4 The composition includes 1 part polyolefin elastomer, 2 parts epoxidized soybean oil, 0.8 parts calcium stearate, 0.4 parts antioxidant, and 0.5 parts heat stabilizer. Waste gas column bag recycled material is sorted, crushed, alkali-washed, water-washed, and dried. It is then melt-extruded and granulated using a single-screw extruder. The alkali washing uses a 1.0% sodium hydroxide solution at 60℃ for 15 minutes. The antioxidant is a blend of antioxidant 1010 and antioxidant 168 in a 1:1.5 mass ratio; the heat stabilizer is a blend of triphenyl phosphite and zinc stearate in a 1.5:1 mass ratio.

[0086] The raw materials for preparing the chitosan-based ternary graft compatibilizer, by weight, include: 5 parts chitosan, 3 parts anhydrous citric acid, 1.5 parts dopamine derivative, 0.6 parts 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.3 parts N-hydroxysuccinimide, and 0.2 parts processing stabilizer. The dopamine derivative is prepared by transesterification of dopamine hydrochloride and glyceryl monostearate in a molar ratio of 1:1.4. The processing stabilizer is prepared by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.5.

[0087] The preparation method of dopamine derivative is as follows: dopamine hydrochloride and glyceryl monostearate are added to anhydrous toluene at a molar ratio of 1:1.3, and 0.7% p-toluenesulfonic acid is added. The mixture is refluxed under vacuum at 85℃ and a gauge pressure of -0.095MPa for 4.5h. After the solvent is removed by vacuum distillation, the reaction solution is purified by recrystallization from ethanol to obtain dopamine derivative with a purity ≥98%.

[0088] The preparation method of chitosan-based ternary graft compatibilizer includes the following steps:

[0089] 1) Disperse chitosan in an aqueous solution of acetic acid with a volume fraction of 1.0%, the amount of acetic acid being 45 times the mass of chitosan, and stir at 400 r / min at 25℃ for 45 min until completely dissolved.

[0090] 2) Add anhydrous citric acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide to the solution obtained in step 1). Stir the mixture at 300 r / min for 18 h at 28 °C. Pour the reaction solution into excess acetone to precipitate the precipitate. After filtration, wash the precipitate three times with ethanol and then vacuum dry it to constant weight at 40 °C and a gauge pressure of -0.085 MPa to obtain anhydrous citric acid grafted chitosan.

[0091] 3) Dissolve anhydrous citric acid-grafted chitosan in 2-morpholine ethanesulfonic acid buffer, the amount of 2-morpholine ethanesulfonic acid buffer being 40 times the mass of anhydrous citric acid-grafted chitosan. Then add processing stabilizer and stir at 400 r / min at 25°C for 28 min to activate. Then add dopamine derivative and continue stirring for 21 h.

[0092] 4) Centrifuge the reaction solution obtained in step 3) at 9500 r / min for 15 min, discard the supernatant, redisperse the precipitate with deionized water and centrifuge again. Repeat the centrifugation and washing process 4 times, and then vacuum dry to constant weight at 55℃ and gauge pressure -0.085 MPa to obtain chitosan-based ternary graft compatibilizer.

[0093] The raw materials for preparing polycaprolactone-coated modified hollow glass microspheres, by weight, include: 10 parts hollow glass microspheres, 1 part 3-aminopropyltriethoxysilane, 0.5 parts 3-hydroxypropyltrimethoxysilane, 20 parts ε-caprolactone, 0.05 parts stannous octoate, and 100 parts toluene.

[0094] The preparation method of polycaprolactone-coated modified hollow glass microspheres includes the following steps:

[0095] (1) The hollow glass microspheres were vacuum dried at 120℃ and -0.085MPa for 6 hours;

[0096] (2) Take 45% of the total weight of toluene and add the dried hollow glass microspheres. Disperse them for 15 min under ultrasonic power of 300 W and frequency of 30 kHz. Add 3-aminopropyltriethoxysilane and 3-hydroxypropyltrimethoxysilane dropwise at a rate of 3 mL / min. After all the dropwise addition is completed, stir the reaction at 300 r / min for 4 h under conditions of 80 °C and gauge pressure of -0.025 MPa. After washing the product three times with toluene, vacuum dry it to constant weight under conditions of 100 °C and gauge pressure of -0.085 MPa to obtain amino-hydroxy bifunctional modified hollow glass microspheres.

[0097] (3) Add the amino-hydroxy bifunctional modified hollow glass microspheres to the remaining toluene, disperse them for 30 min under ultrasonic power of 300 W and frequency of 30 kHz, add ε-caprolactone and stannous octoate, and react for 10 h under nitrogen protection, reflux at 115 °C and 300 r / min.

[0098] (4) Cool the reaction solution obtained in step (3) to 25°C, filter it, wash it three times with n-hexane, and vacuum dry it for 24 hours at 50°C and gauge pressure of -0.085MPa to obtain polycaprolactone-coated modified hollow glass microspheres.

[0099] This embodiment also discloses a method for preparing a bio-based biodegradable cushioning composite material based on waste air column bags, including the following steps:

[0100] S1. Raw material pretreatment: Weigh polylactic acid, polymethyl ethylene carbonate, polybutylene adipate terephthalate, polyolefin elastomer, and recycled waste air column bags according to the proportions, and vacuum dry them at 80℃ and -0.085MPa for 5 hours until the moisture content is ≤0.05%;

[0101] S2. Premixing: The raw materials pretreated in step S1, chitosan-based ternary graft compatibilizer, polycaprolactone-coated modified hollow glass microspheres, epoxy chain extender, epoxidized soybean oil, calcium stearate, antioxidant and heat stabilizer are added to a high-speed mixer and stirred at 700 r / min for 10 min at 25°C to obtain a premix.

[0102] S3. Melt extrusion granulation: The premix obtained in step S2 is added to a co-rotating twin-screw extruder. The temperature of each zone is controlled as follows: feeding section 168℃, conveying section 182℃, melting section 172℃, homogenization section 172℃, and die head section 168℃. The screw speed is 300 r / min, and the vacuum degree of the vacuum exhaust port is gauge pressure -0.085 MPa. After melt blending, extrusion, cooling, and water cooling, the mixture is granulated to obtain composite material masterbatch.

[0103] S4. Molding: The composite material masterbatch obtained in step S3 is vacuum dried at 80℃ and gauge pressure of -0.085MPa for 4 hours, then added to an injection molding machine and molded under the conditions of barrel temperature of 182℃, mold temperature of 32℃, injection pressure of 73MPa, holding pressure of 50MPa, holding time of 22s, and cooling time of 32s to obtain a bio-based biodegradable cushioning composite material.

[0104] Comparative Example 1:

[0105] A bio-based biodegradable cushioning composite material prepared from waste air column bags and its preparation method are disclosed. The only difference between this material and Example 3 is that chitosan-based ternary graft compatibilizer is not added.

[0106] Comparative Example 2:

[0107] A bio-based biodegradable buffer composite material based on waste air column bags and its preparation method are disclosed. The only difference between this material and Example 3 is that polycaprolactone-coated modified hollow glass microspheres are not added.

[0108] Comparative Example 3:

[0109] A bio-based biodegradable buffer composite material prepared from waste air column bags and its preparation method are disclosed. The only difference between this material and Example 3 is that an equal amount of unmodified hollow glass microspheres are used instead of polycaprolactone-coated modified hollow glass microspheres.

[0110] Comparative Example 4:

[0111] A bio-based biodegradable cushioning composite material prepared from waste air column bags and its preparation method are disclosed. The only difference between this material and Example 3 is that an equal amount of maleic anhydride-grafted polypropylene (purchased from Dongguan Jinshixiang Plastic Raw Materials Co., Ltd.) is used to replace the chitosan-based ternary grafting compatibilizer, and the grafting rate of maleic anhydride-grafted polypropylene is 1.0%.

[0112] Comparative Example 5:

[0113] A bio-based biodegradable cushioning composite material prepared from waste air column bags and its preparation method are disclosed. The only difference between this material and Example 3 is that no epoxy chain extender is added.

[0114] Comparative Example 6:

[0115] A bio-based biodegradable cushioning composite material prepared from waste air column bags and its preparation method are disclosed. The only difference between this material and Example 3 is that no polyolefin elastomer is added.

[0116] Comparative Example 7:

[0117] A bio-based biodegradable buffer composite material based on waste air column bags and its preparation method are disclosed. The only difference between this material and Example 3 is that the recycled material from the waste air column bags is directly crushed and fed without alkaline washing pretreatment.

[0118] Comparative Example 8:

[0119] A bio-based biodegradable cushioning composite material prepared from waste air column bags and its preparation method are disclosed. The only difference between this material and Example 3 is that no heat stabilizer is added.

[0120] Comparative Example 9:

[0121] A bio-based biodegradable cushioning composite material based on waste air column bags and its preparation method are disclosed. The only difference between this material and Example 3 is that polymethyl ethylene carbonate is completely replaced with an equal amount of polybutylene adipate terephthalate.

[0122] Comparative Example 10:

[0123] A bio-based biodegradable cushioning composite material prepared from waste air column bags and its preparation method are disclosed. The only difference between this material and Example 3 is that polylactic acid is completely replaced with an equal amount of polybutylene succinate (99% purity, CAS: 25777-14-4, purchased from Wuhan Jixin Yibang Biotechnology Co., Ltd.).

[0124] The mechanical properties, cushioning properties, thermal properties, and degradation properties of the bio-based biodegradable cushioning composite materials prepared from waste air column bags obtained in Examples 1-3 and Comparative Examples 1-10 were tested. The testing methods and standards for each property are as follows:

[0125] (a) Mechanical property testing

[0126] Tensile properties: Tested according to "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics" (GB / T 1040.2-2022), specimen type 1BA, tensile speed 50 mm / min, tensile strength and elongation at break were recorded, 5 specimens were tested in each group, and the arithmetic mean was taken.

[0127] Notched impact strength of cantilever beam: Tested according to the standard "Determination of impact performance of plastic cantilever beam" (GB / T 1843-2023), using type A notch, impact velocity of 3.5 m / s, 10 samples per group, and the arithmetic mean was taken.

[0128] (ii) Buffer performance testing

[0129] Compression stress, strain and rebound rate: The test was conducted according to the "Static Compression Test Method for Packaging Cushioning Materials" (GB / T 8168-2008). The sample size was 100mm×100mm×25mm, the compression speed was 12mm / min, and the sample was compressed to 50% of its original thickness. After compression, the sample was held for 60s to release the pressure. The maximum compression stress and the thickness recovery rate at 60s were recorded, which is the compression rebound rate. Three samples were tested in each group, and the arithmetic mean was taken.

[0130] (III) Thermal performance testing

[0131] Heat distortion temperature: Tested according to "Determination of load distortion temperature of plastics - Part 2: Plastics and hard rubber" (GB / T1634.2-2019), with a load of 0.45 MPa, a heating rate of 120℃ / h, and 3 samples per group, and the arithmetic mean was taken.

[0132] Melt flow rate: Tested according to "Determination of mass flow rate and volumetric flow rate of plastic melt - Part 1: Standard method" (GB / T 3682.1-2018), temperature 190℃, load 2.16kg, 3 tests per group, and the arithmetic mean was taken.

[0133] (iv) Degradation performance testing

[0134] Biodegradation rate: According to the standard GB / T 19277.1-2021, "Determination of final aerobic biodegradation capacity of materials under controlled composting conditions by measuring carbon dioxide released - Part 1: General method", the percentage of biodegradation of the material within 90 days was determined under simulated composting conditions at 58±2℃. This percentage represents the actual chemical degradation rate of the degradable components.

[0135] Mass loss rate: Under the above composting conditions, the percentage of mass loss of the material within 90 days is measured. The calculation formula is: Mass loss rate = (initial mass - residual mass after composting) / initial mass × 100%, which includes the combined effect of chemical degradation of degradable components and physical disintegration of non-degradable components.

[0136] (v) Other tests

[0137] Molecular weight and dispersity of chitosan-based ternary graft compatibilizer: tested by gel permeation chromatography (GPC) with tetrahydrofuran as solvent, flow rate 1.0 mL / min, and column temperature 35℃.

[0138] Polycaprolactone molecular weight and dispersion: determined by gel permeation chromatography (GPC) with chloroform as solvent, flow rate 1.0 mL / min, and column temperature 30℃.

[0139] Microsphere surface functional group density: amino group density was tested by titration, and hydroxyl group density was tested by spectrophotometry;

[0140] Grafting rate of chitosan-based ternary graft compatibilizer: The actual grafting amount of citric acid and dopamine derivatives was calculated by titration.

[0141] The results are shown in Tables 2 and 3.

[0142] Table 2 Test results of mechanical and thermal properties

[0143] Group Tensile strength (MPa) Elongation at break (%) <![CDATA[Izod impact strength (kJ / m 2 )]]> Heat distortion temperature (°C) Melt flow rate (g / 10min) Example 1 21.5 185 10.8 62 6.3 Example 2 24.8 205 12.9 66 5.0 Example 3 26.2 210 14.2 69 3.8 Comparative Example 1 22.7 170 11.3 66 5.2 Comparative Example 2 25.1 195 11.8 70 4.1 Comparative Example 3 23.9 180 10.5 68 4.4 Comparative Example 4 23.2 175 11.5 64 5.0 Comparative Example 5 25.3 200 13.5 68 4.9 Comparative Example 6 25.5 175 11.2 68 4.2 Comparative Example 7 22.1 160 10.1 62 6.5 Comparative Example 8 23.5 185 11.7 66 6.8 Comparative Example 9 23.8 225 13.2 58 5.4 Comparative Example 10 24.5 190 11.9 72 3.7

[0144] Table 3. Test results of buffering performance and degradation performance

[0145] Group Compression rebound rate (%) Maximum compressive stress (kPa) 90-day biodegradation rate (%) 90-day quality loss rate (%) Chitosan compatibilizer grafting rate (%) Example 1 87.0 155 38.5 48.5 32.1 Example 2 89.5 168 42.3 53.3 34.5 Example 3 92.0 180 44.8 56.5 33.8 Comparative Example 1 82.0 148 32.3 42.2 - Comparative Example 2 86.5 170 40.1 50.3 33.6 Comparative Example 3 80.5 156 34.8 43.5 33.7 Comparative Example 4 83.0 152 33.5 44.1 - Comparative Example 5 89.5 172 43.2 54.8 33.5 Comparative Example 6 84.0 176 43.5 54.2 33.7 Comparative Example 7 78.5 135 28.6 38.8 33.4 Comparative Example 8 83.5 158 40.6 51.6 33.9 Comparative Example 9 88.5 145 28.2 39.3 34.1 Comparative Example 10 85.0 178 38.2 49.8 33.3

[0146] Note: Neither Comparative Example 1 nor Comparative Example 4 contained chitosan-based ternary grafted compatibilizers, so the result of the chitosan compatibilizer grafting rate % was marked as "-".

[0147] Using Example 3 as the control group, the performance differences and causes of Comparative Examples 1-10 are analyzed as follows:

[0148] Comparative Example 1: Without the addition of chitosan-based ternary graft compatibilizer, the tensile strength decreased from 26.2 MPa to 22.7 MPa (a decrease of 13.4%), the elongation at break decreased from 210% to 170% (a decrease of 19.0%), and the notched impact strength decreased from 14.2 kJ / m. 2 Reduced to 11.3 kJ / m 2 The melt flow rate increased from 3.8 g / 10 min to 5.2 g / 10 min (an increase of 36.8%), the compression rebound rate decreased from 92.0% to 82.0% (a decrease of 10.9%), the maximum compressive stress decreased from 180 kPa to 148 kPa (a decrease of 17.8%), the 90-day biodegradation rate decreased from 44.8% to 32.3% (a decrease of 27.9%), and the 90-day mass loss rate decreased from 56.5% to 42.2% (a decrease of 25.3%). Chitosan-based ternary graft compatibilizers improve the interfacial bonding between polar bio-based resins and non-polar recycled polypropylene through hydrogen bonding and dipole-dipole interactions, and also possess metal chelation and degradation-promoting functions. The absence of this component significantly weakens interfacial bonding and intensifies phase separation, leading to a comprehensive decline in mechanical properties. Simultaneously, the lack of metal ion chelation accelerates the thermal oxidative degradation of polyester, and the absence of degradation-guiding active sites prevents the provision of anchoring points for microbial degradation, resulting in a substantial reduction in degradation efficiency.

[0149] Comparative Example 2: Hollow glass microspheres without polycaprolactone coating showed a decrease in elongation at break from 210% to 195% (a decrease of 7.1%), and a notched impact strength from 14.2 kJ / m. 2 Reduced to 11.8 kJ / m 2The melt flow rate increased from 3.8 g / 10 min to 4.1 g / 10 min (an increase of 7.9%), the compression rebound rate decreased from 92.0% to 86.5% (a decrease of 6.0%), the maximum compressive stress decreased from 180 kPa to 170 kPa (a decrease of 5.6%), the 90-day biodegradation rate decreased from 44.8% to 40.1% (a decrease of 10.5%), and the 90-day mass loss rate decreased from 56.5% to 50.3% (a decrease of 11.0%). Polycaprolactone-coated modified hollow glass microspheres achieve stress dispersion and impact energy absorption through a core-shell structure of a flexible polycaprolactone layer and a rigid hollow core. Without this component, the material loses its core-shell toughening mechanism and ability to build internal degradation channels, leading to a decrease in toughness and buffering performance. Furthermore, the degradation process can only occur on the material surface, making it difficult for microorganisms and moisture to penetrate the interior, thus reducing degradation efficiency.

[0150] Comparative Example 3: Replacing polycaprolactone-coated modified hollow glass microspheres with an equal amount of unmodified hollow glass microspheres resulted in a decrease in tensile strength from 26.2 MPa to 23.9 MPa (a decrease of 8.8%), elongation at break from 210% to 180% (a decrease of 14.3%), and notched impact strength from 14.2 kJ / m. 2 Reduced to 10.5 kJ / m 2 The melt flow rate increased from 3.8 g / 10 min to 4.4 g / 10 min (an increase of 15.8%), the compression rebound rate decreased from 92.0% to 80.5% (a decrease of 12.5%), the maximum compressive stress decreased from 180 kPa to 156 kPa (a decrease of 13.3%), the 90-day biodegradation rate decreased from 44.8% to 34.8% (a decrease of 22.3%), and the 90-day mass loss rate decreased from 56.5% to 43.5% (a decrease of 23.0%). Unmodified hollow glass microspheres lack active functional groups on their surface, resulting in poor compatibility with the matrix resin and the formation of stress concentration points in the composite material, leading to significant deterioration of mechanical properties. Simultaneously, due to the absence of a polycaprolactone coating layer to guide degradation and construct permeation channels, microorganisms have difficulty penetrating the interior of the microspheres, resulting in a significant decrease in degradation efficiency.

[0151] Comparative Example 4: Replacing the chitosan-based ternary graft compatibilizer with an equal amount of maleic anhydride-grafted polypropylene resulted in a decrease in tensile strength from 26.2 MPa to 23.2 MPa (a decrease of 11.5%), an decrease in elongation at break from 210% to 175% (a decrease of 16.7%), and an increase in notched impact strength from 14.2 kJ / m. 2 Reduced to 11.5 kJ / m 2The heat distortion temperature decreased from 69℃ to 64℃ (a decrease of 7.2%), the melt flow rate increased from 3.8 g / 10 min to 5.0 g / 10 min (an increase of 31.6%), the compression rebound rate decreased from 92.0% to 83.0% (a decrease of 9.8%), the maximum compressive stress decreased from 180 kPa to 152 kPa (a decrease of 15.6%), the 90-day biodegradation rate decreased from 44.8% to 33.5% (a decrease of 25.2%), and the 90-day mass loss rate decreased from 56.5% to 44.1% (a decrease of 22.0%). Maleic anhydride-grafted polypropylene achieves limited chemical compatibility only through a simple esterification reaction between the anhydride groups and the polyester end groups. It lacks metal chelation and biodegradation promoting functions, and its interfacial bonding strength is weaker than that of chitosan-based ternary graft compatibilizers. Furthermore, it cannot inhibit the catalytic effect of metal ions on the thermal oxidative degradation of polyester, resulting in a significant decrease in both the material's mechanical properties and degradation efficiency.

[0152] Comparative Example 5: Without the addition of epoxy chain extender, the melt flow rate increased from 3.8 g / 10 min to 4.9 g / 10 min (an increase of 28.9%). The epoxy chain extender achieves chain extension and repair through the reaction of epoxy groups with the end groups of the polyester molecular chain, thereby improving melt strength. The absence of this component leads to slight breakage of the polyester molecular chain during processing, resulting in a decrease in molecular weight and increased melt flowability, but has little impact on mechanical properties and degradation performance.

[0153] Comparative Example 6: Without the addition of polyolefin elastomer, the elongation at break decreased from 210% to 175% (a decrease of 16.7%), and the notched impact strength decreased from 14.2 kJ / m. 2 Reduced to 11.2 kJ / m 2 (A decrease of 21.1%), melt flow rate increased from 3.8 g / 10 min to 4.2 g / 10 min (an increase of 10.5%), and compression rebound decreased from 92.0% to 84.0% (a decrease of 8.7%). Polyolefin elastomers exhibit excellent compatibility with the polypropylene phase, effectively compensating for matrix brittleness. The absence of this component significantly reduces material toughness, elongation at break, and impact strength, consequently weakening cushioning and rebound performance.

[0154] Comparative Example 7: The recycled material from waste air column bags, without alkali washing pretreatment, showed a decrease in tensile strength from 26.2 MPa to 22.1 MPa (a decrease of 15.6%), elongation at break from 210% to 160% (a decrease of 23.8%), and notched impact strength from 14.2 kJ / m². 2 Reduced to 10.1 kJ / m 2The heat distortion temperature decreased from 69℃ to 62℃ (a decrease of 10.1%), the melt flow rate increased from 3.8 g / 10 min to 6.5 g / 10 min (an increase of 71.1%), the compression rebound rate decreased from 92.0% to 78.5% (a decrease of 14.7%), the maximum compressive stress decreased from 180 kPa to 135 kPa (a decrease of 25.0%), the 90-day biodegradation rate decreased from 44.8% to 28.6% (a decrease of 36.2%), and the 90-day mass loss rate decreased from 56.5% to 38.8% (a decrease of 31.3%). The lack of alkaline washing resulted in residual oil and impurities, damaging the interfacial bonding, and the impurities interfered with the microbial degradation process, leading to a significant deterioration in the overall performance and degradation efficiency of the material.

[0155] Comparative Example 8: Without heat stabilizer, tensile strength decreased from 26.2 MPa to 23.5 MPa (a decrease of 10.3%), elongation at break decreased from 210% to 185% (a decrease of 11.9%), and notched impact strength decreased from 14.2 kJ / m. 2 Reduced to 11.7 kJ / m 2 (A decrease of 17.6%), melt flow rate increased from 3.8 g / 10 min to 6.8 g / 10 min (an increase of 78.9%), compression rebound decreased from 92.0% to 83.5% (a decrease of 9.2%), maximum compressive stress decreased from 180 kPa to 158 kPa (a decrease of 12.2%), 90-day biodegradation rate decreased from 44.8% to 40.6% (a decrease of 9.4%), and 90-day mass loss rate decreased from 56.5% to 51.6% (a decrease of 8.7%). Polymethyl ethylene carbonate is prone to depolymerization and degradation at high temperatures, and specialized heat stabilizers can specifically inhibit this process. The absence of this component leads to the breakage and degradation of polymethyl ethylene carbonate molecular chains, abnormally increased melt flowability, decreased mechanical properties, and a reduction in the effective degradation component.

[0156] Comparative Example 9: When polymethyl ethylene carbonate was completely replaced with an equal amount of polybutylene adipate terephthalate, the tensile strength decreased from 26.2 MPa to 23.8 MPa (a decrease of 9.2%), the elongation at break increased from 210% to 225% (an increase of 7.1%), and the notched impact strength increased from 14.2 kJ / m. 2 Reduced to 13.2 kJ / m 2The heat distortion temperature decreased from 69℃ to 58℃ (a decrease of 15.9%), the melt flow rate increased from 3.8 g / 10 min to 5.4 g / 10 min (an increase of 42.1%), the maximum compressive stress decreased from 180 kPa to 145 kPa (a decrease of 19.4%), the 90-day biodegradation rate decreased from 44.8% to 28.2% (a decrease of 37.1%), and the 90-day mass loss rate decreased from 56.5% to 39.3% (a decrease of 30.4%). Polymethyl ethylene carbonate provides easily hydrolyzable carbonate bonds and gas barrier properties. The absence of this component significantly reduces the material's heat resistance and lacks carbonate bond degradation sites, leading to a substantial decrease in degradation efficiency. Simultaneously, the increased proportion of poly(butylene adipate-terephthalate) slightly improves the material's toughness but reduces its rigidity and heat resistance.

[0157] Comparative Example 10: When polylactic acid was completely replaced with an equal amount of polybutylene succinate, the tensile strength decreased from 26.2 MPa to 24.5 MPa (a decrease of 6.5%), the elongation at break decreased from 210% to 190% (a decrease of 9.5%), and the notched impact strength decreased from 14.2 kJ / m. 2 Reduced to 11.9 kJ / m 2 (A decrease of 16.2%), compression rebound decreased from 92.0% to 85.0% (a decrease of 7.6%), 90-day biodegradability decreased from 44.8% to 38.2% (a decrease of 14.7%), and 90-day mass loss decreased from 56.5% to 49.8% (a decrease of 11.9%). Polylactic acid provides a rigid framework and ester bond degradation sites. The absence of this component weakens the material's rigid support, reduces impact resistance, and decreases degradation sites, leading to reduced degradation efficiency.

[0158] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bio-based biodegradable cushioning composite material prepared from waste air column bags, characterized in that, The raw materials for its preparation, by weight, include: 35-45 parts of recycled waste air column bags, 18-25 parts of polylactic acid, 12-18 parts of polymethyl ethylene carbonate, 8-12 parts of polybutylene adipate terephthalate, 2-4 parts of chitosan-based ternary graft compatibilizer, 3-6 parts of polycaprolactone-coated modified hollow glass microspheres, 0.4-0.8 parts of epoxy chain extender, 0.5-1.5 parts of polyolefin elastomer, 1-3 parts of epoxidized soybean oil, 0.5-1.2 parts of lubricant, 0.2-0.6 parts of antioxidant, and 0.3-0.7 parts of heat stabilizer.

2. The bio-based biodegradable cushioning composite material prepared from waste air column bags according to claim 1, characterized in that, The lubricant is either calcium stearate or erucamide; the antioxidant is a compound of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1 to 1:2; the heat stabilizer is a compound of triphenyl phosphite and zinc stearate in a mass ratio of 1:1 to 2:

1.

3. The bio-based biodegradable cushioning composite material prepared from waste air column bags according to claim 1, characterized in that, The raw materials for preparing the chitosan-based ternary graft compatibilizer, by weight, include: 4-6 parts chitosan, 2-4 parts anhydrous citric acid, 1-2 parts dopamine derivative, 0.5-0.7 parts 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, 0.2-0.4 parts N-hydroxysuccinimide, and 0.1-0.3 parts processing stabilizer; the dopamine derivative is prepared by transesterification of dopamine hydrochloride and glyceryl monostearate in a molar ratio of 1:1.2-1:1.5; the processing stabilizer is prepared by compounding antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1-1:

2.

4. The bio-based biodegradable cushioning composite material prepared from waste air column bags according to claim 3, characterized in that, The preparation method of the chitosan-based ternary graft compatibilizer includes the following steps: 1) Disperse chitosan in an aqueous acetic acid solution with a volume fraction of 0.8-1.2%, the amount of the aqueous acetic acid solution being 40-50 times the mass of the chitosan, and stir at 300-500 r / min at 20-30℃ for 30-60 min until completely dissolved; 2) Add anhydrous citric acid, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide to the solution obtained in step 1). Stir the mixture at 200-400 r / min for 16-20 h at 25-30 °C. Pour the reaction solution into excess acetone to precipitate the precipitate. After filtration, wash the precipitate with ethanol 2-4 times and then vacuum dry it to constant weight at 38-42 °C and a gauge pressure of -0.08-0.09 MPa to obtain anhydrous citric acid grafted chitosan. 3) Dissolve anhydrous citric acid-grafted chitosan in 2-morpholine ethanesulfonic acid buffer, the amount of 2-morpholine ethanesulfonic acid buffer being 35 to 45 times the mass of anhydrous citric acid-grafted chitosan. Then add a processing stabilizer and activate the mixture by stirring at 300 to 500 r / min at 20 to 30°C for 25 to 30 minutes. Subsequently, add a dopamine derivative and continue stirring for 18 to 24 hours. 4) Centrifuge the reaction solution obtained in step 3) at a speed of 9000~10000 r / min for 10~20 min, discard the supernatant, redisperse the precipitate with deionized water and centrifuge again. Repeat this centrifugation and washing process 3~5 times, and then vacuum dry it to constant weight at 50~60℃ and gauge pressure of -0.08~-0.09 MPa to obtain chitosan-based ternary graft compatibilizer.

5. The bio-based biodegradable cushioning composite material prepared from waste air column bags according to claim 1, characterized in that, The preparation method of the dopamine derivative is as follows: dopamine hydrochloride and glyceryl monostearate are added to anhydrous toluene at a molar ratio of 1:1.2 to 1:1.5, and p-toluenesulfonic acid with a mass fraction of 0.5 to 1.0% is added. The mixture is refluxed under vacuum at 80 to 90°C and a gauge pressure of -0.095 MPa for 4 to 5 hours. After the solvent is removed by vacuum distillation, the reaction solution is purified by recrystallization from ethanol to obtain the dopamine derivative.

6. The bio-based biodegradable cushioning composite material prepared from waste air column bags according to claim 1, characterized in that, The raw materials for preparing the polycaprolactone-coated modified hollow glass microspheres, by weight, include: 9-11 parts of hollow glass microspheres, 0.8-1.2 parts of 3-aminopropyltriethoxysilane, 0.4-0.6 parts of 3-hydroxypropyltrimethoxysilane, 18-22 parts of ε-caprolactone, 0.04-0.06 parts of stannous octoate, and 90-110 parts of toluene.

7. The bio-based biodegradable cushioning composite material prepared from waste air column bags according to claim 6, characterized in that, The preparation method of the polycaprolactone-coated modified hollow glass microspheres includes the following steps: (1) Vacuum dry the hollow glass microspheres at 118~122℃ and -0.08~-0.09MPa for 5~7h; (2) Take 40-50% of the total weight of toluene and add dried hollow glass microspheres. Disperse them for 10-20 min under ultrasonic power of 200-400 W and frequency of 20-40 kHz. Add 3-aminopropyltriethoxysilane and 3-hydroxypropyltrimethoxysilane dropwise at a rate of 2-4 mL / min. After all the dropwise addition is completed, stir the reaction at 200-400 r / min for 3-5 h under conditions of 78-82 °C and gauge pressure of -0.02-0.03 MPa. After washing the product with toluene 2-3 times, vacuum dry it to constant weight under conditions of 98-102 °C and gauge pressure of -0.08-0.09 MPa to obtain amino-hydroxy bifunctional modified hollow glass microspheres. (3) Add the amino-hydroxy bifunctional modified hollow glass microspheres to the remaining toluene, disperse them under ultrasonic power of 200~400W and frequency of 20~40kHz for 25~35min, add ε-caprolactone and stannous octoate, and react for 8~12h under nitrogen protection, reflux at 110~120℃ and 200~400r / min. (4) Cool the reaction solution obtained in step (3) to 20~30℃, filter it, wash it with n-hexane 2~4 times, and vacuum dry it at 48~52℃ and gauge pressure -0.08~-0.09MPa for 20~28h to obtain polycaprolactone-coated modified hollow glass microspheres.

8. The bio-based biodegradable cushioning composite material prepared from waste air column bags according to claim 1, characterized in that, The polylactic acid has a weight-average molecular weight of 9 × 10⁻⁶. 4 ~11×10 4 Da, the weight-average molecular weight of the polymethyl ethylene carbonate is 8 × 10⁻⁶. 4 ~12×10 4 Da, the weight-average molecular weight of the poly(butylene adipate-terephthalate) is 15 × 10⁻⁶. 4 ~20×10 4 Da, the weight-average molecular weight of the polyolefin elastomer is 20 × 10⁻⁶. 4 ~30×10 4 Da.

9. A method for preparing a bio-based biodegradable cushioning composite material based on waste air column bags according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Raw material pretreatment: Weigh polylactic acid, polymethyl ethylene carbonate, polybutylene adipate terephthalate, polyolefin elastomer, and recycled waste air column bags according to the proportions, and vacuum dry them at 78~82℃ and -0.08~-0.09MPa for 4~6 hours until the moisture content is ≤0.05%; S2. Premixing: The raw materials pretreated in step S1, chitosan-based ternary graft compatibilizer, polycaprolactone-coated modified hollow glass microspheres, epoxy chain extender, epoxidized soybean oil, lubricant, antioxidant and heat stabilizer are added to a high-speed mixer and stirred at 600-800 r / min at 20-30℃ for 8-12 minutes to obtain a premix. S3. Melt extrusion granulation: The premix obtained in step S2 is added to a co-rotating twin-screw extruder. The temperature of each zone is controlled as follows: feeding section 165~170℃, conveying section 180~185℃, melting section 170~175℃, homogenization section 170~175℃, and die head section 165~170℃. The screw speed is 250~350 r / min, and the vacuum degree of the vacuum exhaust port is -0.08~-0.09 MPa. After melt blending, extrusion, cooling, water cooling, and pelletizing, composite material masterbatch is obtained. S4. Molding: The composite material masterbatch obtained in step S3 is vacuum dried at 75~85℃ and gauge pressure of -0.08~-0.09MPa for 3~5h, then added to an injection molding machine and molded under the conditions of barrel temperature of 175~190℃, mold temperature of 25~40℃, injection pressure of 60~85MPa, holding pressure of 40~60MPa, holding time of 15~30s, and cooling time of 25~40s to obtain a bio-based biodegradable cushioning composite material.

10. The method for preparing the bio-based biodegradable cushioning composite material based on waste air column bags according to claim 9, characterized in that, The recycled waste air column bag material is sorted, crushed, alkali washed, water washed, and dried, and then melt-extruded and granulated through a single screw extruder. The alkali washing uses a sodium hydroxide solution with a mass fraction of 0.8~1.2% and is carried out at 55~65℃ for 10~20 minutes.