Modified ppct biobased degradable material, preparation method and application thereof

Abstract

The application relates to the technical field of degradable materials, in particular to a modified PPCT biobased degradable material, a preparation method and application thereof, which comprises the following steps: S1. high molecular weight PPC is obtained by catalyzing the reaction of carbon dioxide and propylene oxide by using a modified DMC catalyst; S2. high molecular weight PPC, modified polylactic acid, PPC-g-MAH compatilizer and modified anti-aging auxiliary agent are mixed, melt blending and granulating in a double screw extruder, and finally the modified PPCT biobased degradable material is obtained. The synergistic effect of the modified polylactic acid and the modified anti-aging auxiliary agent significantly improves the interface bonding force of PPC and PLA, effectively avoids the stress whitening and performance attenuation problems caused by poor compatibility of a traditional blending system, simultaneously determines the chemical structure of promoting degradation from the source, and effectively solves the problems of "white pollution" and soil compaction caused by traditional mulching films.

Description

Technical Field

[0001] This invention relates to the field of degradation materials technology, specifically to a modified PPCT bio-based degradation material, its preparation method, and its application. Background Technology

[0002] With the increasing global emphasis on carbon neutrality and sustainable development, the development of biodegradable polymer materials using CO2 as a raw material has become a cutting-edge research hotspot. Polypropylene carbonate (PPC) is an aliphatic polycarbonate produced by copolymerizing industrial waste gas carbon dioxide (CO2) with propylene oxide, possessing significant environmental advantages such as renewable raw materials and complete biodegradability. However, traditional PPC suffers from drawbacks such as low molecular weight, poor thermal stability, insufficient toughness, and processing difficulties, severely limiting its application in the field of high-performance materials.

[0003] In existing technologies, PPC performance is often improved by blending with polylactic acid (PLA). However, the poor compatibility between the two leads to a decrease in mechanical properties and a narrow processing window. Furthermore, PPC prepared using common catalysts generally has a low molecular weight (Mn < 80,000), making it difficult to improve the intrinsic properties of the material. Therefore, there is an urgent need to develop a novel high-performance PPC-based composite material to address its performance bottlenecks in practical applications. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a modified PPCT bio-based degradable material, its preparation method, and its application.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a modified PPCT bio-based degradable material includes the following preparation steps: S1. Using a modified DMC catalyst, carbon dioxide and propylene oxide were reacted at 60-90℃ and 1-3MPa for 5-6 hours to obtain high molecular weight PPC (Mn molecular weight ≥100000). S2. By mass, 10-70 parts of high molecular weight PPC, 30-90 parts of modified polylactic acid, 2-5 parts of PPC-g-MAH compatibilizer, and 1-3 parts of modified aging resistant additive are mixed and melt-blended and granulated in a twin-screw extruder at 170-190℃ to finally obtain modified PPCT bio-based degradable material; The preparation of the modified DMC catalyst includes the following steps: S11. By mass, mix 40-50 parts zinc chloride, 70-80 parts tert-butanol and 180-200 parts deionized water to obtain solution A; mix 30-35 parts potassium ferricyanide and 140-150 parts deionized water to obtain solution B; S12. At 38-40℃ and a stirring speed of 750-800r / min, slowly add solution B to solution A over a time of 40-45min. Then add 2-3 parts of nano-silica, 0.6-0.8 parts of cerium nitrate and 6-8 parts of polyethylene glycol 400. Heat to 58-60℃ and stir for aging for 1-2h. S13. The aged mixture obtained in step S12 is centrifuged and filtered to obtain a precipitate, which is washed 3-4 times with tert-butanol aqueous solution, dried at 48-50℃ for 10-12h, and then activated under nitrogen atmosphere for 5-6h to obtain the modified DMC catalyst.

[0006] Preferably, the preparation of modified polylactic acid includes the following steps: S21. By weight, 88-94 parts of polylactic acid (brand name 4032D) and 5-8 parts of PBAT are vacuum dried at 60°C for 7-8 hours; S22. The dried polylactic acid and PBAT are mixed with 0.2-0.3 parts of zinc stearate in a high-speed mixer and then fed into the main feed port of a twin-screw extruder. At the same time, 0.5-1 parts of polyepoxy chain extender (BASF Joncryl ADR4468) and 0.3-0.5 parts of triphenyl phosphite are injected into the side stream. S23. The extrusion product from step S22 is air-dried and granulated, and then dried and dehumidified for 3-4 hours to obtain modified polylactic acid.

[0007] Preferably, the preparation of the modified anti-aging agent includes the following steps: S31. By weight, add 1-1.5 parts of antioxidant 1010, 1-1.5 parts of antioxidant 168, 0.8-1 parts of ultraviolet absorber UV-329 and 0.6-0.8 parts of hindered amine light stabilizer (HALS) into a kneader with a heating jacket, heat to 115-125℃, and stir evenly to obtain a melt. S32. Slowly add the preheated microcrystalline cellulose (MCC) to the melt obtained in step S31, stir evenly, cool to room temperature, add 0.3-0.5 parts of calcium stearate, and grind through a 200-mesh sieve to obtain the modified anti-aging agent.

[0008] Preferably, the screw speed of the twin-screw extruder in step S2 is 100-300 r / min.

[0009] Preferably, the stirring speed in step S12 is 300-400 r / min.

[0010] Preferably, the activation temperature in step S13 is 145-150℃.

[0011] Preferably, the temperature of the twin-screw extruder in step S22 is 160-178°C.

[0012] Preferably, the drying and dehumidification temperature in step S23 is 70°C.

[0013] A modified PPCT bio-based degradable material is prepared by the above preparation method.

[0014] Applications of a modified PPCT bio-based degradable material in biodegradable shopping bags and biodegradable agricultural mulch films: The modified PPCT bio-based degradable material was processed into a 30μm thick film using a blown film process. This film exhibits good mechanical strength and flexibility, and can be directly used for heat sealing to make bags. The resulting shopping bags have strong load-bearing capacity (capable of supporting 5kg of items), a feel similar to traditional PE plastic bags, and are completely degradable by microorganisms in the natural environment.

[0015] The modified PPCT bio-based degradable material was blended with a small amount of natural fillers such as starch and cellulose, and then processed into agricultural mulch films with a thickness of 15-20 μm using casting or blow molding processes. These films possess excellent light transmittance, heat retention, and mechanical strength, meeting the needs of crop growth. After crop harvest, the mulch film can be incorporated into the soil along with the straw, beginning to degrade within 60 days and completely degrading into CO2 and H2O within 90-120 days, thus avoiding the "white pollution" and soil compaction problems caused by traditional mulch films.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention increases the dispersion of catalytic active sites by modifying DMC catalyst, thereby improving catalytic activity and the molecular weight and structural regularity of PPC. It solves the defects of traditional PPC, such as poor thermal stability and insufficient mechanical strength. The synergistic effect of modified polylactic acid and modified anti-aging additives significantly improves the interfacial bonding force between PPC and PLA, effectively avoiding the stress whitening and performance degradation problems caused by poor compatibility in traditional blending systems. At the same time, it determines the chemical structure that promotes degradation from the source, effectively solving the problems of "white pollution" and soil compaction caused by traditional mulch films. Attached Figure Description

[0017] Figure 1 This is a process flow diagram for preparing the modified PPCT bio-based degradable material of the present invention; Figure 2 This is a process flow diagram for preparing the modified DMC catalyst of the present invention; Figure 3 This is a flow chart of the preparation process of the modified polylactic acid of the present invention; Figure 4 This is a flowchart illustrating the preparation process of the modified anti-aging additive of the present invention. Detailed Implementation

[0018] The present invention will now be clearly and completely described in conjunction with embodiments thereof. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] Please see Figures 1-4 The present invention provides a technical solution: Example 1 A method for preparing a modified PPCT bio-based degradable material: Before preparing the modified PPCT bio-based degradable material, the following steps are taken: Modified DMC catalyst, modified polylactic acid, and modified anti-aging additives are prepared. The preparation of the modified DMC catalyst includes the following steps: S11. Mix 40g zinc chloride, 70g tert-butanol and 180g deionized water to obtain solution A; mix 30g potassium ferricyanide and 140g deionized water to obtain solution B; S12. At 38℃ and 750r / min stirring speed, solution B is slowly added to solution A over a period of 40min. Then, 2g of nano silica, 0.6g of cerium nitrate and 6g of polyethylene glycol 400 are added. The temperature is raised to 58℃ and the mixture is stirred at 300r / min for 1h to age the solution. S13. The aged mixture obtained in step S12 is centrifuged and filtered to obtain a precipitate, which is washed three times with tert-butanol aqueous solution, dried at 48°C for 10 h, and then activated at 145°C for 5 h under a nitrogen atmosphere to obtain the modified DMC catalyst.

[0020] The preparation of modified polylactic acid includes the following steps: S21. Dry 88g of polylactic acid (brand name 4032D) and 5g of PBAT under vacuum at 60℃ for 7h; S22. The dried polylactic acid and PBAT are mixed with 0.2g of zinc stearate in a high-speed mixer and then fed into the main feed port of a twin-screw extruder. At the same time, 0.5g of polyepoxy chain extender (BASF Joncryl ADR 4468) and 0.3g of triphenyl phosphite are injected into the side stream. The feeding section temperature is set to 160℃, the mixing section to 170℃, the homogenization section to 178℃, and the die head to 175℃. S23. The extrusion product from step S22 is air-dried and granulated, and then dried at 70°C for 3 hours to obtain modified polylactic acid.

[0021] The preparation of modified anti-aging additives includes the following steps: S31. Add 1g of antioxidant 1010, 1g of antioxidant 168, 0.8g of ultraviolet absorber UV-329 and 0.6g of hindered amine light stabilizer into a kneader with a heating jacket, heat to 115℃, and stir evenly to obtain a molten liquid. S32. Slowly add the preheated microcrystalline cellulose to the melt obtained in step S31, stir evenly, cool to room temperature, add 0.3g of calcium stearate, and grind through a 200-mesh sieve to obtain the modified anti-aging agent.

[0022] The preparation of modified PPCT bio-based degradable materials includes the following steps: S1. Using a modified DMC catalyst, carbon dioxide and propylene oxide were reacted at 60℃ and 1MPa for 5h to obtain high molecular weight PPC; S2. Mix 10g of high molecular weight PPC, 30g of modified polylactic acid, 2g of PPC-g-MAH compatibilizer, and 1g of modified anti-aging agent obtained in step S1, and melt-blend and granulate them in a twin-screw extruder at 170°C with a screw speed of 100r / min to finally obtain modified PPCT bio-based degradable material.

[0023] Example 2 A method for preparing a modified PPCT bio-based degradable material: Before preparing the modified PPCT bio-based degradable material, the following steps are taken: Modified DMC catalyst, modified polylactic acid, and modified anti-aging additives are prepared. The preparation of the modified DMC catalyst includes the following steps: S11. Mix 50g zinc chloride, 80g tert-butanol and 200g deionized water to obtain solution A; mix 35g potassium ferricyanide and 150g deionized water to obtain solution B; S12. At 40℃ and 800r / min stirring speed, solution B is slowly added to solution A over a period of 45min. Then, 3g of nano silica, 0.8g of cerium nitrate and 8g of polyethylene glycol 400 are added. The temperature is raised to 60℃ and the mixture is stirred at 400r / min for 2h to age. S13. The aged mixture obtained in step S12 is centrifuged and filtered to obtain a precipitate, which is washed four times with tert-butanol aqueous solution, dried at 50°C for 12 hours, and then activated at 150°C for 6 hours under a nitrogen atmosphere to obtain the modified DMC catalyst.

[0024] The preparation of modified polylactic acid includes the following steps: S21. 94g of polylactic acid (brand name 4032D) and 8g of PBAT were vacuum dried at 60℃ for 8h; S22. The dried polylactic acid and PBAT are mixed with 0.3g of zinc stearate in a high-speed mixer and then fed into the main feed port of a twin-screw extruder. At the same time, 1g of polyepoxy chain extender (BASF Joncryl ADR 4468) and 0.5g of triphenyl phosphite are injected into the side stream. The feeding section temperature is set to 160℃, the mixing section to 175℃, the homogenization section to 178℃, and the die head to 175℃. S23. The extrusion product from step S22 is air-dried and granulated, and then dried at 70°C for 4 hours to obtain modified polylactic acid.

[0025] The preparation of modified anti-aging additives includes the following steps: S31. Add 1.5g antioxidant 1010, 1.5g antioxidant 168, 1g ultraviolet absorber UV-329 and 0.8g hindered amine light stabilizer into a kneader with a heating jacket, heat to 125℃, and stir evenly to obtain a molten liquid. S32. Slowly add the preheated microcrystalline cellulose to the melt obtained in step S31, stir evenly, cool to room temperature, add 0.5g of calcium stearate, and grind through a 200-mesh sieve to obtain the modified anti-aging agent.

[0026] The preparation of modified PPCT bio-based degradable materials includes the following steps: S1. Using a modified DMC catalyst, carbon dioxide and propylene oxide were reacted at 90℃ and 3MPa for 6 hours to obtain high molecular weight PPC; S2. Mix 70g of high molecular weight PPC, 90g of modified polylactic acid, 5g of PPC-g-MAH compatibilizer, and 3g of modified anti-aging agent obtained in step S1, and melt-blend and granulate them in a twin-screw extruder at 190°C with a screw speed of 300r / min to finally obtain modified PPCT bio-based degradable material.

[0027] Example 3 A method for preparing a modified PPCT bio-based degradable material: Before preparing the modified PPCT bio-based degradable material, the following steps are taken: Modified DMC catalyst, modified polylactic acid, and modified anti-aging additives are prepared. The preparation of the modified DMC catalyst includes the following steps: S11. Mix 45g zinc chloride, 75g tert-butanol and 190g deionized water to obtain solution A; mix 32g potassium ferricyanide and 145g deionized water to obtain solution B; S12. At 39℃ and 780r / min stirring speed, solution B is slowly added to solution A over a period of 42min. Then, 2.5g of nano silica, 0.7g of cerium nitrate and 7g of polyethylene glycol 400 are added. The temperature is raised to 59℃ and the mixture is stirred at 35r / min for 1.5h to age. S13. The aged mixture obtained in step S12 is centrifuged and filtered to obtain a precipitate, which is washed three times with tert-butanol aqueous solution, dried at 49°C for 11 h, and then activated at 148°C for 5.5 h under a nitrogen atmosphere to obtain the modified DMC catalyst.

[0028] The preparation of modified polylactic acid includes the following steps: S21. 90g of polylactic acid (brand name 4032D) and 6g of PBAT were vacuum dried at 60℃ for 7.5h; S22. The dried polylactic acid and PBAT are mixed with 0.25g of zinc stearate in a high-speed mixer and then fed into the main feed port of a twin-screw extruder. At the same time, 0.7g of polyepoxy chain extender (BASF Joncryl ADR 4468) and 0.4g of triphenyl phosphite are injected into the side stream. The feeding section temperature is set to 160℃, the mixing section to 172℃, the homogenization section to 178℃, and the die head to 175℃. S23. The extrusion product from step S22 is air-dried and granulated, and then dried at 70°C for 3.5 hours to obtain modified polylactic acid.

[0029] The preparation of modified anti-aging additives includes the following steps: S31. Add 1.3g antioxidant 1010, 1.3g antioxidant 168, 0.9g ultraviolet absorber UV-329 and 0.7g hindered amine light stabilizer into a kneader with a heating jacket, heat to 120℃, and stir evenly to obtain a molten liquid. S32. Slowly add the preheated microcrystalline cellulose to the melt obtained in step S31, stir evenly, cool to room temperature, add 0.4g of calcium stearate, and grind through a 200-mesh sieve to obtain the modified anti-aging agent.

[0030] The preparation of modified PPCT bio-based degradable materials includes the following steps: S1. Using a modified DMC catalyst, carbon dioxide and propylene oxide were reacted at 70℃ and 2MPa for 5.5h to obtain high molecular weight PPC; S2. Mix 30g of high molecular weight PPC, 50g of modified polylactic acid, 3g of PPC-g-MAH compatibilizer, and 2g of modified anti-aging agent obtained in step S1, and melt-blend and granulate them in a twin-screw extruder at 180°C with a screw speed of 200r / min to finally obtain modified PPCT bio-based degradable material.

[0031] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that the modified DMC catalyst in this comparative example is replaced with a common DMC catalyst. The remaining steps are exactly the same in Comparative Example 1 and Example 1.

[0032] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that the modified polylactic acid is replaced with ordinary polylactic acid (grade 4032D) in this comparative example. The remaining steps are exactly the same in Comparative Example 2 and Example 1.

[0033] Comparative Example 3 The only difference between Comparative Example 3 and Example 1 is that no modified anti-aging additive was added to this comparative example; the other steps are exactly the same in Comparative Example 3 and Example 1.

[0034] Performance testing: The tensile strength and elongation at break of the modified PPCT bio-based degradable materials obtained in Examples 1-3 and Comparative Examples 1-3 were tested according to GB / T 1040.3-2006 "Tension Properties Test of Plastic Films and Sheets". The materials were blown into 30 μm films, cut into dumbbell-shaped specimens, and stretched at a speed of 200 mm / min.

[0035] The thermal stability (TGA) of the modified PPCT bio-based degradable materials obtained in Examples 1-3 and Comparative Examples 1-3 was tested according to GB / T 27761-2011 "Test Methods for Weight Loss and Residual Amounts in Thermogravimetric Analyzer". Under a nitrogen atmosphere, the heating rate was 10 °C / min, and the 5% thermogravimetric temperature (Td, 5%) was recorded.

[0036] The biodegradability of the modified PPCT bio-based degradable materials obtained in Examples 1-3 and Comparative Examples 1-3 was tested according to GB / T 19277.1-2011 "Determination of Final Aerobic Biodegradability of Materials under Controlled Composting Conditions". The biodegradation rate was measured after 120 days under controlled composting conditions (58℃). The final results are shown in Table 1 below: Table 1 Performance Test Results As shown in Table 1, the modified PPCT bio-based degradable materials obtained in Examples 1-3 of this invention outperform the comparative examples in all aspects. This indicates that the modified DMC catalyst, modified polylactic acid, and modified anti-aging additives form a synergistic effect to varying degrees, improving the overall performance of the modified PPCT bio-based degradable materials. This results in superior mechanical properties, thermal stability, and biodegradability, demonstrating significant technological advancement and practical application value. It effectively solves the problems of "white pollution" and soil compaction caused by traditional mulch films.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a modified PPCT bio-based degradable material, characterized in that, The preparation steps include the following: S1. Using a modified DMC catalyst, carbon dioxide and propylene oxide were reacted at 60-90℃ and 1-3MPa for 5-6 hours to obtain high molecular weight PPC; S2. By mass, 10-70 parts of high molecular weight PPC, 30-90 parts of modified polylactic acid, 2-5 parts of PPC-g-MAH compatibilizer, and 1-3 parts of modified aging resistant additive are mixed and melt-blended and granulated in a twin-screw extruder at 170-190℃ to finally obtain modified PPCT bio-based degradable material; The preparation of the modified DMC catalyst includes the following steps: S11. By mass, mix 40-50 parts zinc chloride, 70-80 parts tert-butanol and 180-200 parts deionized water to obtain solution A; mix 30-35 parts potassium ferricyanide and 140-150 parts deionized water to obtain solution B; S12. At 38-40℃ and a stirring speed of 750-800r / min, slowly add solution B to solution A over a time of 40-45min. Then add 2-3 parts of nano-silica, 0.6-0.8 parts of cerium nitrate and 6-8 parts of polyethylene glycol 400. Heat to 58-60℃ and stir for aging for 1-2h. S13. The aged mixture obtained in step S12 is centrifuged and filtered to obtain a precipitate, which is washed 3-4 times with tert-butanol aqueous solution, dried at 48-50℃ for 10-12h, and then activated under nitrogen atmosphere for 5-6h to obtain the modified DMC catalyst.

2. The method for preparing a modified PPCT bio-based degradable material according to claim 1, characterized in that, The preparation of the modified polylactic acid includes the following steps: S21. By weight, 88-94 parts of polylactic acid and 5-8 parts of PBAT are vacuum dried at 60°C for 7-8 hours; S22. Mix the dried polylactic acid and PBAT with 0.2-0.3 parts of zinc stearate in a high-speed mixer, and then feed the mixture into the main feed port of a twin-screw extruder. At the same time, inject 0.5-1 parts of polyepoxy chain extender and 0.3-0.5 parts of triphenyl phosphite into the side stream. S23. The extrusion product from step S22 is air-dried and granulated, and then dried and dehumidified for 3-4 hours to obtain modified polylactic acid.

3. The method for preparing a modified PPCT bio-based degradable material according to claim 1, characterized in that, The preparation of the modified anti-aging agent includes the following steps: S31. By weight, 1-1.5 parts of antioxidant 1010, 1-1.5 parts of antioxidant 168, 0.8-1 parts of ultraviolet absorber UV-329 and 0.6-0.8 parts of hindered amine light stabilizer are put into a kneader with a heating jacket, heated to 115-125℃, and stirred evenly to obtain a melt. S32. Slowly add the preheated microcrystalline cellulose to the melt obtained in step S31, stir evenly, cool to room temperature, add 0.3-0.5 parts of calcium stearate, and grind through a 200-mesh sieve to obtain the modified aging resistant additive.

4. The method for preparing a modified PPCT bio-based degradable material according to claim 1, characterized in that, In step S2, the screw speed of the twin-screw extruder is 100-300 r / min.

5. The method for preparing a modified PPCT bio-based degradable material according to claim 1, characterized in that, The stirring speed in step S12 is 300-400 r / min.

6. The method for preparing a modified PPCT bio-based degradable material according to claim 1, characterized in that, The activation temperature in step S13 is 145-150℃.

7. The method for preparing a modified PPCT bio-based degradable material according to claim 2, characterized in that, In step S22, the temperature of the twin-screw extruder is 160-178℃.

8. The method for preparing a modified PPCT bio-based degradable material according to claim 2, characterized in that, The drying and dehumidification temperature in step S23 is 70℃.

9. A modified PPCT bio-based degradable material, characterized in that, It is prepared by the preparation method described in any one of claims 1-8.

10. The application of the modified PPCT bio-based degradable material according to claim 9 in degradable shopping bags and degradable agricultural mulch films.

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