A bio-based degradable foamed sandwich express packaging box material and a preparation method thereof

Abstract

This invention relates to the field of bio-based polymer materials technology, and discloses a bio-based biodegradable foamed sandwich express delivery packaging box material and its preparation method. The foamed sandwich express delivery packaging box material prepared by this invention uses polybutylene adipate terephthalate (PAT) as the main bio-based raw material, with added polylactic acid (PLA) as a compound, and then adds PLA-g-GMA, a bio-based composite flame retardant, a crosslinking agent, a plasticizer, and antioxidants, etc., before foaming. This material not only has excellent foaming performance but also good mechanical properties. The addition of the bio-based composite flame retardant improves the flame retardant performance of the material without sacrificing its mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of bio-based polymer materials technology, specifically to a bio-based biodegradable foamed sandwich express packaging box material and its preparation method. Background Technology

[0002] Statistics show that approximately 5.8 million tons of expanded polystyrene (EPS) are used for packaging globally each year. Its production and disposal processes generate substantial carbon emissions, placing immense pressure on the ecological environment. Against this backdrop, the "Opinions on Further Strengthening the Governance of Plastic Pollution" issued by relevant government departments explicitly states that by the end of 2025, postal and express delivery outlets nationwide will be prohibited from using non-degradable plastic packaging bags. This provides clear policy guidance for the research and application of bio-based biodegradable packaging materials.

[0003] Currently, research on bio-based foam materials mainly focuses on the blending and modification of biodegradable polyesters such as polylactic acid (PLA) and polybutylene terephthalate (PBAT). However, pure PLA foaming suffers from technical bottlenecks such as low melt strength and a narrow foaming window, while PBAT, although possessing good flexibility, has poor flame retardant properties, limiting its application in high-end packaging. Therefore, developing bio-based composite materials that combine excellent foaming performance, mechanical strength, and flame retardancy has become a key area for the industry to address. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a bio-based biodegradable foamed sandwich express packaging box material and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions: A bio-based biodegradable foamed sandwich express packaging box material, comprising the following raw materials in parts by weight: 100 parts polybutylene adipate terephthalate, 15-25 parts polylactic acid, 3-6 parts PLA-g-GMA, 4-8 parts bio-based composite flame retardant, 1-3 parts crosslinking agent, 2-4 parts plasticizer, and 1-3 parts antioxidant. Furthermore, the crosslinking agent is benzoyl peroxide; Further, the plasticizer is one or more of dioctyl adipate, triethyl citrate, epoxidized soybean oil, or dioctyl sebacate; Furthermore, the antioxidant is one of antioxidant 1076, antioxidant 1010, or antioxidant 264; The bio-based composite flame retardant is prepared by the following steps: Step A1: Mix vanillin and 2,5-bis(aminomethyl)furan in anhydrous ethanol and stir until homogeneous. Heat to 45-65℃ and stir under nitrogen atmosphere for 7-9 hours. Rotary evaporate, wash and dry to obtain vanillin-furan derivative. Furthermore, in step A1, the molar ratio of vanillin to 2,5-bis(aminomethyl)furan is 1:1; Step A2: Mix vanillin-furan derivative and phosphorous acid separately in deionized water and stir until homogeneous, and label them as solution 1 and solution 2. Slowly add solution 2 to solution 1 and stir until homogeneous. Then heat to 70-80℃ and stir for 12 hours. Remove the solvent by rotary evaporation, wash and dry to obtain phosphorous acid-vanillin-furan derivative. Furthermore, in step A2, the molar ratio of vanillin-furan derivative to phosphorous acid is 1:2; Step A3: Add imidazole-1-acetic acid, phosphorous acid-vanillin-furan derivative, and sodium bisulfate to toluene and stir thoroughly. Then transfer to an oil bath, stir, and heat to 120°C and continue stirring until anhydrous (TLC detection). Add saturated sodium bicarbonate solution and stir for 15 minutes. Filter under reduced pressure and dry to obtain the bio-based composite flame retardant. Furthermore, in step A3, the ratio of imidazole-1-acetic acid, phosphorous acid-vanillin-furan derivative, sodium bisulfate, and saturated sodium bicarbonate solution is 0.02-0.025 mol: 0.01 mol: 0.05-0.06 mol: 200 mL.

[0006] A method for preparing a bio-based biodegradable foamed sandwich express packaging box material includes the following steps: Step S1: Weigh the raw materials according to the weight parts, add polybutylene adipate terephthalate, polylactic acid, PLA-g-GMA, bio-based composite flame retardant, crosslinking agent, plasticizer and antioxidant into the mixer and mix evenly to obtain the premix. Step S2: The premixed material is fed into a twin-screw extruder, extruded, cooled, and granulated at 170-190℃, and then hot-pressed at 120-160℃ through a flat vulcanizing machine. Subsequently, it is foamed for 1-2 hours under supercritical carbon dioxide at 10MPa-20MPa and 80-100℃. After the foaming is completed, the pressure is released within 1-3 seconds, and the material is cooled and shaped to obtain the bio-based biodegradable foamed sandwich express packaging box material.

[0007] The beneficial effects of this invention are: The foamed sandwich express packaging box material prepared by this invention uses polybutylene adipate terephthalate (PAT) as the main bio-based raw material, with added polylactic acid (PLA) as a compound, and then mixed with functional additives such as PLA-g-GMA, bio-based composite flame retardant, crosslinking agent, plasticizer, and antioxidant before foaming. This material not only has excellent foaming performance but also good mechanical properties. The addition of the bio-based composite flame retardant improves the flame retardant performance of the material without sacrificing its mechanical properties.

[0008] The bio-based composite flame retardant introduced in this invention uses vanillin and 2,5-di(aminomethyl)furan as bio-based raw materials, and then introduces imidazole rings and phosphorous acid through chemical bonding. Utilizing their synergistic effect, the material is endowed with excellent flame retardant properties. Specifically, the phosphorus element provided by the phosphorous acid portion decomposes at high temperatures to generate phosphoric acid or polyphosphoric acid, a strong dehydrating agent. This catalyzes the dehydration and carbonization of the polymer (PBAT / PLA) surface, forming a dense, porous carbon layer. This carbon layer acts like a "fireproof suit," isolating oxygen, hindering heat transfer, and preventing the escape of flammable gases, thus interrupting combustion. Vanillin and the furan ring are themselves carbon-rich structures; they can serve as the "base material" for char formation, intertwining with the phosphorus-catalyzed carbon layer, making the carbon layer more stable and dense, thereby improving the heat insulation and oxygen barrier effects. The imidazole ring is rich in nitrogen. When burning, it can decompose and release non-combustible gases such as ammonia and nitrogen. These gases can not only dilute the oxygen concentration on the surface of the material, but also capture high-energy free radicals in the combustion chain reaction, thereby inhibiting the spread of flame in the gas phase. More importantly, nitrogen and phosphorus have a significant synergistic effect, which can promote the efficiency of phosphorus catalytic carbonization and achieve a significant flame retardant effect.

[0009] Furthermore, PLA-g-GMA is added to the foamed sandwich express packaging box material. As a compatibilizer, it improves the compatibility of the matrix and enhances the interfacial bonding between raw materials. This enhanced interfacial bonding makes the cell walls stronger during the foaming process, reducing the likelihood of breakage and resulting in a more regular cell structure. Simultaneously, when the material is subjected to external forces, stress can be evenly transferred to the matrix through this "molecular bridge," providing reinforcement and improving the material's mechanical properties. Detailed Implementation

[0010] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0011] Example 1: Bio-based composite flame retardant was prepared by the following steps: Step A1: Mix vanillin and 2,5-di(aminomethyl)furan in anhydrous ethanol and stir until homogeneous. Heat to 45°C and stir under nitrogen atmosphere for 7-9 hours. Rotary evaporate, wash and dry to obtain vanillin-furan derivative. The molar ratio of vanillin to 2,5-di(aminomethyl)furan is 1:1. Step A2: Mix vanillin-furan derivative and phosphorous acid separately in deionized water and stir until homogeneous, and label them as solution 1 and solution 2. Slowly add solution 2 to solution 1 and stir until homogeneous. Then heat to 70℃ and stir for 12 hours. Remove the solvent by rotary evaporation, wash, and dry to obtain phosphorous acid-vanillin-furan derivative. The molar ratio of vanillin-furan derivative to phosphorous acid is 1:2. Step A3: Add imidazole-1-acetic acid, phosphorous acid-vanillin-furan derivative, and sodium bisulfate to toluene and stir thoroughly. Then transfer to an oil bath, stir, and heat to 120°C, stirring continuously until anhydrous (TLC detection). Add saturated sodium bicarbonate solution and stir for 15 min. Filter under reduced pressure and dry to obtain the bio-based composite flame retardant. The ratio of imidazole-1-acetic acid, phosphorous acid-vanillin-furan derivative, sodium bisulfate, and saturated sodium bicarbonate solution is 0.02 mol: 0.01 mol: 0.05 mol: 200 mL.

[0012] Example 2: Bio-based composite flame retardant was prepared by the following steps: Step A1: Mix vanillin and 2,5-di(aminomethyl)furan in anhydrous ethanol and stir until homogeneous. Heat to 55°C and stir under nitrogen atmosphere for 8 hours. Rotary evaporate, wash and dry to obtain vanillin-furan derivative. The molar ratio of vanillin to 2,5-di(aminomethyl)furan is 1:1. Step A2: Mix vanillin-furan derivative and phosphorous acid separately in deionized water and stir until homogeneous, and label them as solution 1 and solution 2. Slowly add solution 2 to solution 1 and stir until homogeneous. Then heat to 75℃ and stir for 12 hours. Remove the solvent by rotary evaporation, wash, and dry to obtain phosphorous acid-vanillin-furan derivative. The molar ratio of vanillin-furan derivative to phosphorous acid is 1:2. Step A3: Add imidazole-1-acetic acid, phosphorous acid-vanillin-furan derivative, and sodium bisulfate to toluene and stir thoroughly. Then transfer to an oil bath, stir, and heat to 120°C, stirring continuously until anhydrous (TLC detection). Add saturated sodium bicarbonate solution and stir for 15 min. Filter under reduced pressure and dry to obtain the bio-based composite flame retardant. The ratio of imidazole-1-acetic acid, phosphorous acid-vanillin-furan derivative, sodium bisulfate, and saturated sodium bicarbonate solution is 0.023 mol: 0.01 mol: 0.055 mol: 200 mL.

[0013] Example 3: Bio-based composite flame retardant was prepared by the following steps: Step A1: Mix vanillin and 2,5-di(aminomethyl)furan in anhydrous ethanol and stir until homogeneous. Heat to 65°C and stir under nitrogen atmosphere for 9 hours. Rotary evaporate, wash and dry to obtain vanillin-furan derivative. The molar ratio of vanillin to 2,5-di(aminomethyl)furan is 1:1. Step A2: Mix vanillin-furan derivative and phosphorous acid separately in deionized water and stir until homogeneous, and label them as solution 1 and solution 2. Slowly add solution 2 to solution 1 and stir until homogeneous. Then heat to 80℃ and stir for 12 hours. Remove the solvent by rotary evaporation, wash, and dry to obtain phosphorous acid-vanillin-furan derivative. The molar ratio of vanillin-furan derivative to phosphorous acid is 1:2. Step A3: Add imidazole-1-acetic acid, phosphorous acid-vanillin-furan derivative, and sodium bisulfate to toluene and stir thoroughly. Then transfer to an oil bath, stir, and heat to 120°C, stirring continuously until anhydrous (TLC detection). Add saturated sodium bicarbonate solution and stir for 15 min. Filter under reduced pressure and dry to obtain the bio-based composite flame retardant. The ratio of imidazole-1-acetic acid, phosphorous acid-vanillin-furan derivative, sodium bisulfate, and saturated sodium bicarbonate solution is 0.025 mol: 0.01 mol: 0.06 mol: 200 mL.

[0014] Example 4: A method for preparing a bio-based biodegradable foamed sandwich express packaging box material includes the following steps: 100 parts of polybutylene adipate terephthalate, 15 parts of polylactic acid, 3 parts of PLA-g-GMA, 4 parts of the bio-based composite flame retardant prepared in Example 1, 1 part of benzoyl peroxide, 2 parts of dioctyl adipate, and 1 part of antioxidant 1076. Step S1: Weigh the raw materials according to the weight parts, add polybutylene adipate terephthalate, polylactic acid, PLA-g-GMA, the bio-based composite flame retardant prepared in Example 1, benzoyl peroxide, dioctyl adipate and antioxidant 1076 into a mixer and mix evenly to obtain the premix. Step S2: The premixed material is fed into a twin-screw extruder, extruded, cooled, and granulated at 170-190℃, and then hot-pressed at 120℃ through a flat vulcanizing machine. Subsequently, it is foamed for 1 hour under supercritical carbon dioxide at 10MPa and 80℃. After the foaming is completed, the pressure is released within 1 second, and the material is cooled and shaped to obtain the bio-based biodegradable foamed sandwich express packaging box material.

[0015] Example 5: A method for preparing a bio-based biodegradable foamed sandwich express packaging box material includes the following steps: 100 parts of polybutylene adipate terephthalate, 20 parts of polylactic acid, 4.5 parts of PLA-g-GMA, 6 parts of the bio-based composite flame retardant prepared in Example 2, 2 parts of benzoyl peroxide, 3 parts of triethyl citrate, and 2 parts of antioxidant 1010. Step S1: Weigh the raw materials according to the weight parts, add polybutylene adipate terephthalate, polylactic acid, PLA-g-GMA, the bio-based composite flame retardant prepared in Example 2, benzoyl peroxide, triethyl citrate and antioxidant 1010 into a mixer and mix evenly to obtain the premix. Step S2: The premixed material is fed into a twin-screw extruder, extruded, cooled, and granulated at 170-190℃, and then hot-pressed at 140℃ through a flat vulcanizing machine. Subsequently, it is foamed for 1.5 hours under supercritical carbon dioxide at 15MPa and 90℃. After the foaming is completed, the pressure is released within 2 seconds, and the material is cooled and shaped to obtain the bio-based biodegradable foamed sandwich express packaging box material.

[0016] Example 6: A method for preparing a bio-based biodegradable foamed sandwich express packaging box material includes the following steps: 100 parts of polybutylene adipate terephthalate, 25 parts of polylactic acid, 6 parts of PLA-g-GMA, 8 parts of the bio-based composite flame retardant prepared in Example 3, 3 parts of benzoyl peroxide, 4 parts of epoxidized soybean oil, and 3 parts of antioxidant 264. Step S1: Weigh the raw materials according to the weight parts, add polybutylene adipate terephthalate, polylactic acid, PLA-g-GMA, the bio-based composite flame retardant prepared in Example 3, benzoyl peroxide, epoxidized soybean oil and antioxidant 264 into a mixer and mix evenly to obtain the premix. Step S2: The premixed material is fed into a twin-screw extruder, extruded, cooled, and granulated at 170-190℃, and then hot-pressed at 160℃ through a flat vulcanizing machine. Subsequently, it is foamed for 2 hours under supercritical carbon dioxide at 20MPa and 100℃. After the foaming is completed, the pressure is released within 3 seconds, and the material is cooled and shaped to obtain the bio-based biodegradable foamed sandwich express packaging box material.

[0017] Comparative Example 1: This comparative example is a material for express packaging boxes. The difference between this example and Example 6 is that ammonium polyphosphate is used instead of the bio-based composite flame retardant prepared in Example 3. All other aspects are the same.

[0018] Comparative Example 2: This comparative example is a material for express packaging boxes. The difference between this example and Example 6 is that magnesium hydroxide is used instead of the bio-based composite flame retardant prepared in Example 3. All other aspects are the same.

[0019] Comparative Example 3: This comparative example is a type of express packaging box material. The difference between this example and Example 6 is that no plasticizer was added.

[0020] Comparative Example 4: This comparative example is a type of express packaging box material. The difference between this example and Example 6 is that PLA-g-GMA is not added.

[0021] The performance of the express packaging box materials prepared in Examples 4-6 and Comparative Examples 1-3 was tested: Mechanical property testing: according to national standard GB / T 6344 The 2008 standard, "Determination of Tensile Strength and Elongation at Break of Flexible Foam Polymer Materials," tested the tensile strength and elongation at break. Expansion ratio: The expansion ratio is tested using an expansion ratio tester; Flame retardant performance test: The limiting oxygen index was tested according to GB / T 2406.1-2008 "Determination of Combustion Behavior of Plastics by Oxygen Index Method"; the test results are shown in Table 1. Table 1: Performance Test Results

[0022] As can be seen from Table 1, the express packaging box materials prepared in Examples 4-6 have better mechanical properties, foaming properties and flame retardant properties than the materials prepared in Comparative Examples 1-4.

[0023] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the scope defined by the inventive concept, they should all fall within the protection scope of the present invention.

Claims

1. A bio-based biodegradable foamed sandwich express packaging box material, characterized in that, The raw materials include the following parts by weight: 100 parts polybutylene adipate terephthalate, 15-25 parts polylactic acid, 3-6 parts PLA-g-GMA, 4-8 parts bio-based composite flame retardant, 1-3 parts crosslinking agent, 2-4 parts plasticizer, and 1-3 parts antioxidant. The bio-based composite flame retardant is prepared by reacting imidazole-1-acetic acid and phosphorous acid-vanillin-furan derivative with sodium bisulfate as catalyst at 120°C; the phosphorous acid-vanillin-furan derivative is prepared by reacting vanillin-furan derivative and phosphorous acid at 70-80°C for 12 hours; the vanillin-furan derivative is prepared by reacting vanillin and 2,5-di(aminomethyl)furan at 45-65°C for 7-9 hours.

2. The bio-based biodegradable foamed sandwich express packaging box material according to claim 1, characterized in that, The bio-based composite flame retardant is prepared by the following steps: Step A1: Mix vanillin and 2,5-bis(aminomethyl)furan in anhydrous ethanol and stir until homogeneous. Heat to 45-65℃ and stir under nitrogen atmosphere for 7-9 hours. Rotary evaporate, wash and dry to obtain vanillin-furan derivative. Step A2: Mix vanillin-furan derivative and phosphorous acid separately in deionized water and stir until homogeneous, and label them as solution 1 and solution 2. Slowly add solution 2 to solution 1 and stir until homogeneous. Then heat to 70-80℃ and stir for 12 hours. Remove the solvent by rotary evaporation, wash and dry to obtain phosphorous acid-vanillin-furan derivative. Step A3: Add imidazole-1-acetic acid, phosphorous acid-vanillin-furan derivative, and sodium bisulfate to toluene and stir thoroughly. Then transfer to an oil bath, stir, and heat to 120°C and continue stirring until anhydrous. Add saturated sodium bicarbonate solution and stir for 15 minutes. Filter under reduced pressure and dry to obtain the bio-based composite flame retardant.

3. The bio-based biodegradable foamed sandwich express packaging box material according to claim 2, characterized in that, In step A1, the molar ratio of vanillin to 2,5-bis(aminomethyl)furan is 1:

1.

4. The bio-based biodegradable foamed sandwich express packaging box material according to claim 2, characterized in that, In step A2, the molar ratio of vanillin-furan derivative to phosphorous acid is 1:

2.

5. The bio-based biodegradable foamed sandwich express packaging box material according to claim 2, characterized in that, In step A3, the ratio of imidazole-1-acetic acid, phosphorous acid-vanillin-furan derivative, sodium bisulfate, and saturated sodium bicarbonate solution is 0.02-0.025 mol: 0.01 mol: 0.05-0.06 mol: 200 mL.

6. The bio-based biodegradable foamed sandwich express packaging box material according to claim 1, characterized in that, The crosslinking agent is benzoyl peroxide.

7. The bio-based biodegradable foamed sandwich express packaging box material according to claim 1, characterized in that, The plasticizer is one or more of dioctyl adipate, triethyl citrate, epoxidized soybean oil, or dioctyl sebacate.

8. The bio-based biodegradable foamed sandwich express packaging box material according to claim 1, characterized in that, The antioxidant is one of antioxidant 1076, antioxidant 1010, or antioxidant 264.

9. A method for preparing a bio-based biodegradable foamed sandwich express packaging box material according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1: Weigh the raw materials according to the weight parts, add polybutylene adipate terephthalate, polylactic acid, PLA-g-GMA, bio-based composite flame retardant, crosslinking agent, plasticizer and antioxidant into the mixer and mix evenly to obtain the premix. Step S2: The premixed material is fed into a twin-screw extruder, extruded, cooled, and granulated at 170-190℃, and then hot-pressed at 120-160℃ through a flat vulcanizing machine. Subsequently, it is foamed for 1-2 hours under supercritical carbon dioxide at 10MPa-20MPa and 80-100℃. After the foaming is completed, the pressure is released within 1-3 seconds, and the material is cooled and shaped to obtain the bio-based biodegradable foamed sandwich express packaging box material.

Images