Preparation method of degradable bio-based plastic storage box
By modifying fillers with angelica root powder and kudzu root powder and using a multi-layer co-injection process, a biodegradable bio-based plastic storage box with a skin-foamed core structure was prepared, which solved the problems of uneven rigidity and toughness, slow degradation and high cost, and achieved efficient biodegradation and lightweighting.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIANGSU JIUTONG PLASTIC MFG CO LTD
- Filing Date
- 2026-03-18
- Publication Date
- 2026-05-26
AI Technical Summary
Existing biodegradable bio-based plastic storage boxes have problems in terms of balancing rigidity and toughness, easy deformation and cracking, long degradation induction period and high cost, making it difficult to meet market demand.
Angelica dahurica powder and kudzu root powder are used as fillers, and a multi-layer co-injection process is used to form a skin-foamed core structure. High-temperature calcination and oxygen activation treatment are used to enhance the bonding force of PLA/PBAT matrix. Modified starch and foamed core layer design are introduced to form a composite structure of dense surface layer and microporous foamed core layer.
It achieves high biodegradability, good impact resistance and load-bearing capacity, reduces product density and production costs, has anti-mildew and antibacterial effects, and meets lightweight design requirements.
Smart Images
Figure CN122080592A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of plastic products technology, specifically to a method for preparing a biodegradable bio-based plastic storage box, and more particularly to a biodegradable composite material reinforced with plant-derived modified fillers, as well as a technique for preparing a storage box with a skin-foamed core structure through a multi-layer co-injection process. Background Technology
[0002] Storage boxes are essential tools for home organization and logistics, and most mainstream products on the market are currently made of polypropylene (PP) or polyethylene (PE). These petroleum-based plastics are difficult to degrade, causing serious white pollution when discarded. With increasingly stringent environmental regulations and rising consumer awareness of environmental protection, the development of biodegradable, bio-based plastic storage boxes has become a trend.
[0003] Existing technologies have reported the preparation of biodegradable products using polylactic acid (PLA) or polybutylene adipate terephthalate (PBAT). However, pure PLA is brittle and has poor heat resistance, making it prone to cracking at stress points such as the corners of storage boxes; while PBAT, although flexible, lacks rigidity, causing the products to easily deform and collapse. Furthermore, simple blending modification often leads to filler agglomeration, resulting in limited improvement in mechanical properties. Moreover, existing biodegradable storage boxes are mostly homogeneous structures, requiring large amounts of material, resulting in high costs and weight, which does not conform to lightweight design principles.
[0004] Therefore, how to improve the overall mechanical properties and reduce the cost of storage boxes through the synergistic effect of material modification and structural design while ensuring complete biodegradability is a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing a biodegradable bio-based plastic storage box, which has advantages such as excellent mechanical properties, high biodegradability, mildew and antibacterial properties, lightweight and controllable cost. It solves the problems of poor rigidity-toughness balance, easy deformation and cracking, long degradation induction period, and high production cost that make it difficult to promote in the market.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] A method for preparing a biodegradable bio-based plastic storage box includes the following steps:
[0008] S1. Preparation of bio-modified filler: Angelica dahurica powder and kudzu root powder are mixed at a mass ratio of 1:1.5~2.5, placed in an oxygen atmosphere, and activated pretreated at 120~140℃ for 1~2h; then, plasticizer equivalent to 30~50% of the total mass of the mixture is added, and the mixture is heated to 160~180℃ for calcination grafting reaction for 3~5h. After cooling, it is pulverized to obtain bio-modified filler.
[0009] S2, Substrate mixing: The bio-modified filler obtained in step S1 is mixed with modified starch and coupling agent in a high-speed mixer for the first surface modification to obtain modified mixture A;
[0010] S3. Melt blending: The biodegradable matrix resin, toughening agent, compatibilizer and modified mixture A obtained in step S2 are added to a twin-screw extruder for melt blending extrusion and granulation to obtain bio-based composite material particles.
[0011] S4. Injection molding: The composite material particles obtained in step S3 are injected into the storage box mold, and a multi-layer co-injection process is used to mold a semi-finished storage box with a composite structure having a dense surface layer and a foamed core layer.
[0012] S5. Post-processing: Anneal the semi-finished product, then assemble the lid and latches to obtain the finished product.
[0013] Furthermore, the particle size of the angelica powder and kudzu powder mentioned in step S1 is 200-400 mesh; the plasticizer is at least one of epoxidized soybean oil, tributyl citrate or palm oil.
[0014] Furthermore, the modified starch mentioned in step S2 is corn starch or cassava starch modified with a silane coupling agent, with a degree of substitution of 0.02 to 0.05; the coupling agent is a titanate coupling agent, and its addition amount is 0.5 to 1.5% of the total mass of the bio-modified filler and the modified starch.
[0015] Furthermore, the biodegradable matrix resin mentioned in step S3 is a blend of polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), and polybutylene succinate (PBS), with a mass ratio of (30~40):(40~50):(10~20).
[0016] Furthermore, the weight proportions of each component in step S3 are as follows: 100 parts of biodegradable matrix resin, 15-25 parts of biomodified filler, 10-20 parts of modified starch, 5-10 parts of toughening agent, 2-5 parts of compatibilizer, and 0.5-1 part of antioxidant.
[0017] Furthermore, the toughening agent is polycaprolactone (PCL) or bio-based polyurethane; the compatibilizer is either glycidyl methacrylate grafted PBAT (PBAT-g-GMA) or maleic anhydride grafted PLA (PLA-g-MAH).
[0018] Furthermore, the multi-layer co-injection process described in step S4 is as follows: the first injection injects the particles without foaming agent obtained in step S3 into the mold cavity to form a surface layer; the second injection injects the same particles containing supercritical nitrogen or physical foaming agent into the core of the mold cavity, and after mold opening and expansion, a foamed core layer is formed. The surface layer thickness is 0.5~1.5mm, and the core layer density is 0.4~0.7 g / cm³.
[0019] Furthermore, the annealing treatment in step S5 is carried out at a temperature of 60~80℃ and for a time of 30~90min, in order to eliminate internal stress and improve crystallinity.
[0020] Another technical problem that this invention aims to solve is to provide a biodegradable bio-based plastic storage box, which includes a box body and a box lid. The box body is provided with reinforcing ribs at its corners and edges, and the box body is made of a composite material with a dense surface layer and a microporous foam core layer.
[0021] Furthermore, the storage box has a biodegradation rate of over 90% after being buried in the soil for 12 months, and its body can withstand a vertical compressive load of ≥2500N, and it does not break during a drop test (from a height of 1.2 meters).
[0022] Compared with existing technologies, this invention provides a method for preparing a biodegradable bio-based plastic storage box, which has the following beneficial effects:
[0023] 1. The preparation method of this biodegradable bio-based plastic storage box involves treating Angelica dahurica and Pueraria lobata powder using a specific process (oxygen atmosphere, high-temperature calcination) to induce cross-linking of their macromolecular chains or activation of functional groups, resulting in stronger interfacial bonding with the subsequent PLA / PBAT matrix. Combined with the "skin-foamed core" structure formed by the multi-layer co-injection process, the storage box maintains its lightweight while exhibiting significantly better impact resistance and load-bearing capacity than ordinary blended modified biodegradable plastic products.
[0024] 2. The preparation method of this biodegradable bio-based plastic storage box utilizes the natural plant components (angelica and kudzu root) in the biomodified filler, which are highly hygroscopic and prone to mold growth in soil, attracting microbial accumulation and triggering the biodegradation process of the PLA / PBAT matrix. This solves the problem of long degradation induction period of biodegradable plastics in the natural environment.
[0025] 3. The preparation method of this biodegradable bio-based plastic storage box utilizes the natural antibacterial components such as coumarins contained in angelica powder, which retain some activity after high-temperature calcination and grafting. This gives the storage box a good anti-mildew effect during storage and use, without the need to add additional chemical anti-mildew agents.
[0026] 4. The preparation method of this biodegradable bio-based plastic storage box reduces the amount of expensive biodegradable resin by introducing inexpensive modified starch and plant-derived modified fillers, thus lowering raw material costs. Simultaneously, the foamed core layer design reduces the product weight by 15-25%, aligning with the reduction principles of green packaging. Attached Figure Description
[0027] Figure 1 This is a process flow diagram of the preparation method of a biodegradable bio-based plastic storage box according to the present invention.
[0028] Figure 2 This is a process flow diagram of the modified starch preparation method for a biodegradable bio-based plastic storage box according to the present invention. Detailed Implementation
[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.
[0030] I. Preparation Example:
[0031] Example 1:
[0032] Please see Figures 1 to 2 The preparation method of a biodegradable bio-based plastic storage box in this embodiment includes the following steps:
[0033] S1. Preparation of bio-modified filler: Mix 20 kg of 200-mesh angelica root powder and 30 kg of 200-mesh kudzu root powder, add to a reaction vessel, introduce oxygen, and activate at 130℃ for 1.5 h. Then add 25 kg of epoxidized soybean oil, heat to 170℃, and stir and calcine for 4 h. After the reaction is complete, cool and pulverize to 300-mesh powder to obtain the bio-modified filler.
[0034] S2. Preparation of modified starch: Tapioca starch and 1% by mass titanate coupling agent are treated in a high-speed mixer at 80°C for 20 min to obtain modified starch.
[0035] S3. Mixing and Granulation: Weigh 35 parts PLA, 45 parts PBAT, and 20 parts PBS by weight as the matrix resin; weigh 20 parts of the bio-modified filler prepared in step S1, 15 parts of the modified starch prepared in step S2, 8 parts of PCL toughening agent, 3 parts of PBAT-g-GMA compatibilizer, and 0.5 parts of antioxidant 1010. Premix all powder materials (bio-modified filler and modified starch) with coupling agent (adding an additional 0.5 parts of titanate) in a high-speed mixer for 5 minutes to obtain modified mixture A. Then, add modified mixture A, matrix resin, toughening agent, compatibilizer, and antioxidant together to a twin-screw extruder, set the melt temperature to 150~165℃, and extrude and granulate to obtain composite material particles.
[0036] S4. Injection Molding: A two-color injection molding machine with a supercritical fluid foaming unit is used. First, the particles from step 3 (without foaming agent) are injected into the mold to form a dense surface layer; then, the same particles containing supercritical nitrogen are injected into the core of the mold cavity. After mold opening and expansion, a foamed core layer is formed, with the surface layer thickness controlled at 1.0mm. The resulting semi-finished storage box has dimensions of 400mm × 300mm × 200mm.
[0037] S5. Post-processing: Place the semi-finished product in a 70℃ oven for annealing for 60 minutes, then install the lid and latches to obtain the finished storage box A1.
[0038] Example 2:
[0039] This embodiment is basically the same as Embodiment 1, except that:
[0040] In step S1, the mass ratio of Angelica dahurica to Pueraria lobata is 1:1 (25 kg each), and the plasticizer is replaced with palm oil. In step S3, the matrix resin is adjusted to 40 parts PLA, 50 parts PBAT, and 10 parts PBS. The resulting finished product is storage box A2.
[0041] Comparative Example 1:
[0042] Commercially available pure PP resin was used, with the addition of conventional nucleating agents, and storage boxes of the same specifications were molded using ordinary injection molding process, serving as a traditional petroleum-based control example D1.
[0043] Comparative Example 2:
[0044] Instead of preparing the bio-modified filler in step S1, untreated plant fiber powder (corn stalk powder) was directly used as a substitute. It was mixed with PLA / PBAT in the same proportion as in Example 1 and then injection molded without using a multi-layer foaming process, resulting in Control Example D2.
[0045] II. Performance Testing:
[0046] The storage boxes prepared in Examples 1-2 and Comparative Examples 1-2 were subjected to performance tests, and the test methods are as follows:
[0047] Biodegradability: The biodegradability was determined at 60 days and 180 days under controlled composting conditions, in accordance with GB / T 19277.1.
[0048] Compression resistance: Refer to GB / T 4857.4, conduct a vertical compression test under no-load conditions, and record the maximum load when the box deforms.
[0049] Drop test: Refer to GB / T 4857.5, perform a free drop from a height of 1.2 meters and check whether the box body has cracks.
[0050] Apparent density: Calculate the apparent density by measuring the overall mass and volume of the container.
[0051] The test results are recorded in Table 1.
[0052] Table 1: Performance Comparison of Storage Boxes Prepared in Each Example and Comparative Example
[0053] Test Project Example A1 Example A2 Comparative Example D1 Comparative Example D2 180-day biodegradability 95.2% 93.5% 5.6% 78.3% Compressive load (N) 2850 2720 3100 1850 1.2m drop test No cracks No cracks No cracks Slight cracks at the edges Apparent density (g / cm³) 0.65 0.68 0.91 0.95 Cost estimate (RMB / unit) 8.5 8.2 7.8 9.5
[0054] III. Results Analysis:
[0055] As shown in Table 1, the storage boxes prepared in Examples A1 and A2 of this invention, while ensuring a high biodegradability rate (over 90%), achieve a compressive load of 2850N through material modification (Angelica dahurica / Pueraria lobata activation) and structural optimization (peel-foamed structure), which is very close to traditional PP plastic (3100N) and far exceeds that of ordinary blended modified biodegradable storage boxes (1850N). Drop tests show that the product of this invention has good toughness and no breakage. In addition, the design of the foamed core layer significantly reduces the product density, achieving lightweighting, and keeping the cost within a competitive range (slightly higher than PP, but far lower than poor-performing biodegradable products). Comparative Example D2, due to its unmodified filler and homogeneous structure, has poor mechanical properties, high density, and high cost, making it impractical. In summary, this invention successfully prepares a biodegradable bio-based plastic storage box with excellent comprehensive performance and controllable cost.
[0056] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0057] 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 biodegradable bio-based plastic storage box, characterized in that, Includes the following steps: S1. Preparation of bio-modified filler: Angelica dahurica powder and kudzu root powder are mixed at a mass ratio of 1:1.5~2.5, placed in an oxygen atmosphere, and activated pretreated at 120~140℃ for 1~2h; then, plasticizer equivalent to 30~50% of the total mass of the mixture is added, and the mixture is heated to 160~180℃ for calcination grafting reaction for 3~5h. After cooling, it is pulverized to obtain bio-modified filler. S2. Substrate mixing: The bio-modified filler obtained in step S1 is mixed with modified starch and coupling agent in a high-speed mixer for the first surface modification to obtain modified mixture A. S3. Melt blending: The biodegradable matrix resin, toughening agent, compatibilizer and modified mixture A obtained in step S2 are added to a twin-screw extruder for melt blending extrusion and granulation to obtain bio-based composite material particles. S4. Injection molding: The composite material particles obtained in step S3 are injected into the storage box mold, and a multi-layer co-injection process is used to mold a semi-finished storage box with a composite structure having a dense surface layer and a foamed core layer. S5. Post-processing: Anneal the semi-finished product, then assemble the lid and latches to obtain the finished product.
2. The method for preparing a biodegradable bio-based plastic storage box according to claim 1, characterized in that, The particle size of the angelica powder and kudzu powder mentioned in step S1 is 200-400 mesh; the plasticizer is at least one of epoxidized soybean oil, tributyl citrate or palm oil.
3. The method for preparing a biodegradable bio-based plastic storage box according to claim 1, characterized in that, The modified starch mentioned in step S2 is corn starch or cassava starch modified with a silane coupling agent, with a degree of substitution of 0.02 to 0.05; the coupling agent is a titanate coupling agent, and its addition amount is 0.5 to 1.5% of the total mass of the bio-modified filler and the modified starch.
4. The method for preparing a biodegradable bio-based plastic storage box according to claim 1, characterized in that, The biodegradable matrix resin mentioned in step S3 is a blend of polylactic acid (PLA), polybutylene adipate terephthalate (PBAT) and polybutylene succinate (PBS), with a mass ratio of (30~40):(40~50):(10~20).
5. The method for preparing a biodegradable bio-based plastic storage box according to claim 1, characterized in that, The weight proportions of each component in step S3 are as follows: 100 parts of biodegradable matrix resin, 15-25 parts of biomodified filler, 10-20 parts of modified starch, 5-10 parts of toughening agent, 2-5 parts of compatibilizer, and 0.5-1 part of antioxidant.
6. The method for preparing a biodegradable bio-based plastic storage box according to claim 1, characterized in that, The toughening agent is polycaprolactone (PCL) or bio-based polyurethane; the compatibilizer is either glycidyl methacrylate grafted PBAT (PBAT-g-GMA) or maleic anhydride grafted PLA (PLA-g-MAH).
7. The method for preparing a biodegradable bio-based plastic storage box according to claim 1, characterized in that, The multi-layer co-injection process described in step S4 is as follows: the first injection injects the particles without foaming agent obtained in step S3 into the mold cavity to form a surface layer; the second injection injects the same particles containing supercritical nitrogen or physical foaming agent into the core of the mold cavity, and after mold opening and expansion, a foamed core layer is formed. The surface layer thickness is 0.5~1.5mm, and the core layer density is 0.4~0.7 g / cm³.
8. The method for preparing a biodegradable bio-based plastic storage box according to claim 1, characterized in that, The annealing process described in step S5 is performed at a temperature of 60-80°C for 30-90 minutes to eliminate internal stress and improve crystallinity.
9. A biodegradable bio-based plastic storage box, characterized in that, The biodegradable bio-based plastic storage box is prepared by the method described in any one of claims 1-8. The storage box includes a box body and a box lid. The corners and edges of the box body are provided with reinforcing ribs. The material of the box body is a composite structure of a dense surface layer and a microporous foamed core layer formed by the composite material described in claim 3.
10. A biodegradable bio-based plastic storage box according to claim 9, characterized in that, The storage box has a biodegradation rate of over 90% after being buried in the soil for 12 months. Its body can withstand a vertical compressive load of ≥2500N and shows no breakage in a drop test (1.2 meters high).