Bamboo fiber reinforced sterile degradable material and preparation method thereof

Abstract

The application discloses a kind of bamboo fiber reinforced sterile degradable materials and preparation method thereof, it is related to polyester degradable plastic technical field, the material includes following formula: polylactic acid, polybutylene adipate terephthalate, bamboo fiber, bamboo powder, compatibility agent, toughening agent, lubricant, flow aid, antibacterial agent, antioxidant, ultraviolet stabilizer and nucleating agent.The application forms stable multi-phase interface transition structure in material by constructing composite material system, effectively improves the interface bonding strength between bamboo fiber and matrix, so as to significantly improve the mechanical properties and anti-cracking ability of material;At the same time, through the synergistic effect of antibacterial agent and stabilizing aid, the material can still maintain molecular structure stability and have sustained antibacterial ability under sterilization treatment condition, thereby realizing the comprehensive optimization of material strength, sterile performance and degradability, to meet the multiple requirements of safety, reliability and environmental friendliness of biological medicine container.

Description

Technical Field

[0001] This invention relates to the field of polyester biodegradable plastics technology, specifically to a bamboo fiber reinforced sterile biodegradable material and its preparation method. Background Technology

[0002] With the continuous improvement of green environmental protection concepts and biomedical safety standards, the application of biodegradable polymer materials in the container packaging field is gradually increasing, especially in scenarios such as pharmaceutical packaging, reagent containers, and disposable medical consumables, which place higher demands on the non-toxicity, biodegradability, and aseptic compatibility of materials. In existing technologies, commonly used biodegradable materials are mostly polylactic acid or its blends. Although they possess certain biodegradability, their bulk materials generally suffer from insufficient toughness and poor impact resistance, making them prone to cracking or brittle failure during injection molding or blow molding, failing to meet the structural reliability requirements of medical containers during transportation and use. To improve mechanical properties, some solutions introduce natural plant fibers (such as bamboo fiber) for reinforcement. However, due to the strong surface polarity and easy water absorption of bamboo fiber, its interfacial compatibility with polyester matrices is poor, resulting in loose interfacial bonding and low stress transfer efficiency. This creates defect sources within the material, ultimately reducing overall mechanical properties and stability. Furthermore, existing technologies largely rely on subsequent sterilization processes to achieve "sterile" performance, lacking a systematic design for the antibacterial properties and sterilization stability of the material itself. During gamma-ray or ethylene oxide sterilization, molecular chain breakage or performance degradation can easily occur, making it difficult to simultaneously ensure the long-term stability and safety of the material. Therefore, how to achieve interfacial stability in bamboo fiber reinforced systems while ensuring material biodegradability, and simultaneously improve the material's aseptic compatibility and post-sterilization performance retention, has become a key technical problem urgently needing to be solved in this field. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a bamboo fiber reinforced sterile biodegradable material and its preparation method, thereby solving the problems mentioned in the background section.

[0004] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a bamboo fiber reinforced sterile and biodegradable material, which comprises the following formulation by weight parts: Polylactic acid 50-80 parts; 10-30 parts of poly(butylene adipate / terephthalate); 10-25 parts bamboo fiber; Bamboo powder 5-15 parts; 2-6 parts compatibilizer; 5-12 parts toughening agent; Lubricant 0.5 to 2 parts; 1-4 parts of flow aid; Antibacterial agent 0.2-1 part; Antioxidant 0.2–0.8 parts; 0.1 to 0.5 parts of UV stabilizer; Nucleating agent 0.5 to 2 parts.

[0005] To further optimize this technical solution, the bamboo fiber is a short-cut bamboo fiber that has undergone surface modification treatment. The length of the bamboo fiber is 0.2-1 mm, the aspect ratio is 5-20, and the moisture content is controlled below 3%.

[0006] To further optimize this technical solution, the bamboo fiber is obtained through the following method: First, place the bamboo fiber in a sodium hydroxide solution with a mass concentration of 2% to 6% and soak it for 30 to 90 minutes at room temperature to 60°C to remove surface lignin and impurities. The bamboo fibers were then repeatedly washed with deionized water until neutral and dried at 80–110°C for 2–6 hours. The dried bamboo fibers were then immersed in a 0.5%–2% silane coupling agent solution for 10–30 minutes and dried again to form a uniform coupling layer structure on the surface of the bamboo fibers, thus changing the surface of the bamboo fibers from hydrophilic to oleophilic.

[0007] To further optimize this technical solution, the compatibilizer is a maleic anhydride-grafted polyester compatibilizer, wherein the grafting rate of maleic anhydride in the compatibilizer is 0.5% to 2.5%, and the number average molecular weight of the compatibilizer is 2 × 10⁻⁶. 4 ~8×10 4 .

[0008] To further optimize this technical solution, the compatibilizer is prepared by the following method: Polylactic acid and maleic anhydride were fed into a twin-screw extruder at a mass ratio of 100:1 to 5 at 160–190°C, and a melt grafting reaction was carried out under the action of a peroxide initiator. The amount of the peroxide initiator added is 0.2% to 0.8%, the reaction time is 3 to 10 min, and the compatibilizer is obtained by cooling and granulation.

[0009] To further optimize this technical solution, the antibacterial agent is an inorganic antibacterial agent, including silver-based or zinc-based antibacterial agents. The antibacterial agent exists in a carrier-loaded form, and the carrier is silicate or oxide particles. The average particle size of the antibacterial agent is 50–200 nm, and the mass fraction of active metal ions in the antibacterial agent is 0.5%–5%. The antibacterial agent is prepared by loading silver ions or zinc ions onto the surface of a porous silicate carrier.

[0010] To further optimize this technical solution, the toughening agent is a thermoplastic elastomer, including polyester elastomers or olefin elastomers, the glass transition temperature of the toughening agent is -30℃ to 0℃, and the melt flow rate is 5 to 20 g / 10 min. The toughening agent is distributed in the biodegradable matrix as a dispersed phase during melt blending, forming an elastic phase micro-region structure with a size of 0.5 to 3 μm.

[0011] To further optimize this technical solution, the nucleating agent is an inorganic nucleating agent or an organic nucleating agent, including talc or organic small molecule nucleating agents. The particle size of the nucleating agent is 1-5 μm, and its distribution in the material is uniformly dispersed. The nucleating agent provides crystallization induction sites in the polylactic acid matrix, increasing the crystallization initiation temperature by 3-10°C and shortening the crystallization time, thereby enabling the material to form a uniform and refined grain structure during injection molding or injection stretch blow molding.

[0012] To further optimize this technical solution, the polylactic acid and poly(butylene adipate / terephthalate) form a biodegradable matrix system; The bamboo fiber and bamboo powder constitute a synergistic reinforcing and filling system; The compatibilizer is used to improve the interfacial bonding performance between the biodegradable matrix system and the synergistic reinforcing filler system; The antibacterial agent, antioxidant, and UV stabilizer constitute a sterile stabilization auxiliary system, which is used to improve the structural stability and antibacterial properties of the material under sterilization conditions.

[0013] A method for preparing a bamboo fiber reinforced sterile biodegradable material, based on the above-mentioned bamboo fiber reinforced sterile biodegradable material, includes the following steps: S1. Directional surface modification treatment is applied to bamboo fiber to construct the structural basis for subsequent interfacial bonding; S2. Based on the modified bamboo fiber obtained in S1, a compatibilizer is constructed and an interfacial bridging component is formed to achieve synergy in the multiphase system. S3. Based on the components obtained from S1 and S2, low-moisture-content premixing and dispersion are carried out to form a stable composite raw material system; S4. Based on the premix obtained in S3, perform melt blending and extrusion to construct a multiphase coupled microstructure system; S5. Based on the composite material particles obtained in S4, perform drying and crystal structure regulation treatment to adapt to subsequent molding processes. S6. Use the particles obtained in S5 to process containers to form biodegradable products with sterile properties.

[0014] Compared with the prior art, the present invention provides a bamboo fiber reinforced sterile biodegradable material and its preparation method, which has the following beneficial effects: This bamboo fiber reinforced sterile biodegradable material and its preparation method construct a composite material system with polylactic acid and PBAT as the matrix, surface-modified bamboo fiber and bamboo powder as synergistic reinforcing phases, and introduces a specific structural compatibilizer and an inorganic antibacterial system. This system forms a stable multiphase interface transition structure within the material, effectively improving the interfacial bonding strength between the bamboo fiber and the matrix, thereby significantly improving the material's mechanical properties and crack resistance. Simultaneously, through the synergistic effect of antibacterial agents and stabilizing agents, the material maintains molecular structural stability and possesses continuous antibacterial ability under sterilization conditions, thus achieving comprehensive optimization of material strength, sterility, and biodegradability. This meets the multiple requirements of biomedical containers for safety, reliability, and environmental friendliness. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic flowchart of a method for preparing a bamboo fiber reinforced sterile biodegradable material proposed in this invention. Detailed Implementation

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0018] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0019] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0020] A bamboo fiber reinforced sterile and biodegradable material, comprising the following formulation by weight parts: Polylactic acid (PLA) 50-80 parts; as the main biodegradable matrix of the material, it provides basic molding properties and structural strength, while also endowing the material with good biodegradability, meeting the environmental protection and safety requirements of medical containers.

[0021] Polybutylene adipate / terephthalate (PBAT) 10-30 parts; used to improve the brittleness of polylactic acid system, enhance the ductility and impact resistance of material by forming a flexible phase structure, and enhance the rupture resistance of container during transportation and use.

[0022] Bamboo fiber, 10-25 parts; as the main reinforcing phase, forms a skeleton support structure inside the material, improving the material's rigidity, bending resistance and dimensional stability, while also endowing the material with natural bio-based properties.

[0023] Bamboo powder 5-15 parts; as a filler and reinforcing component, it forms a multi-scale synergistic structure with bamboo fiber to improve material density and optimize cost, while also improving the molding stability and surface texture of the product.

[0024] Compatibilizer 2-6 parts; used to improve the interfacial bonding performance between polyester matrix and bamboo fiber and bamboo powder, by forming a transition layer structure at the interface to improve stress transfer efficiency and reduce interfacial defects.

[0025] 5-12 parts of toughening agent; form a dispersed elastic phase structure in the matrix to absorb impact energy and inhibit crack propagation, thereby improving the impact resistance and fatigue resistance of the material.

[0026] Lubricant 0.5 to 2 parts; used to reduce internal and external friction of materials during processing, improve melt flowability and demolding performance, thereby improving molding efficiency and reducing product defects.

[0027] 1-4 parts of flow aid; used to adjust the melt flow characteristics of materials to make them suitable for molding processes such as injection molding, injection stretch blow molding and extrusion blow molding, thereby improving processing stability and product molding accuracy.

[0028] Antibacterial agent 0.2 to 1 part; used to impart continuous antibacterial properties to the material, forming an antibacterial environment on the surface and inside of the material, meeting the requirements of biomedical containers for sterility and safety.

[0029] Antioxidant 0.2-0.8 parts; used to inhibit the thermo-oxidative degradation reaction that occurs during the processing and sterilization of materials, maintain the stability of the molecular chain structure, and thus extend the service life of the materials.

[0030] 0.1 to 0.5 parts of UV stabilizer; used to improve the stability of materials under light exposure, prevent performance degradation and discoloration caused by UV radiation, and ensure long-term stability of container appearance and performance.

[0031] Nucleating agent 0.5 to 2 parts; used to regulate the crystallization behavior of polylactic acid matrix, improve the crystallization rate by providing crystallization induction sites, thereby improving the dimensional stability and mechanical property consistency of the material.

[0032] The polylactic acid and poly(butylene adipate / terephthalate) form a biodegradable matrix system, the bamboo fiber and bamboo powder form a synergistic reinforcing and filling system, and the compatibilizer is used to improve the interfacial bonding performance between the biodegradable matrix system and the synergistic reinforcing and filling system.

[0033] The antibacterial agent, antioxidant, and UV stabilizer constitute a sterile stabilization auxiliary system, which is used to improve the structural stability and antibacterial properties of the material under sterilization conditions.

[0034] This material is suitable for manufacturing biomedical containers using injection molding, injection stretch blow molding, or extrusion blow molding processes.

[0035] The compatibilizer is preferably a maleic anhydride-grafted polyester compatibilizer, wherein the grafting rate of maleic anhydride in the compatibilizer is 0.5% to 2.5%, and the number average molecular weight of the compatibilizer is 2 × 10⁻⁶. 4 ~8×10 4 The compatibilizer is prepared by the following method: polylactic acid and maleic anhydride are added to a twin-screw extruder at a mass ratio of 100:(1-5) under the condition of 160-190℃, and a melt grafting reaction is carried out under the action of a peroxide initiator. The amount of the initiator added is 0.2%-0.8%, the reaction time is 3-10 min, and the compatibilizer is obtained by cooling and granulation. The compatibilizer forms polar grafted segments in the material system and constructs a continuous transition layer structure at the interface between the polylactic acid / polybutylene adipate terephthalate matrix and bamboo fiber and bamboo powder, thereby improving the interfacial shear strength.

[0036] The bamboo fiber is a short-cut bamboo fiber that has undergone surface modification treatment. The length of the bamboo fiber is 0.2-1 mm, the aspect ratio is 5-20, and the moisture content is controlled below 3%. The bamboo fiber is obtained by the following method: First, the raw bamboo fiber is placed in a sodium hydroxide solution with a mass concentration of 2%-6% and soaked for 30-90 minutes at room temperature to 60°C to remove surface lignin and impurities. Then, it is repeatedly washed with deionized water until neutral and dried at 80-110°C for 2-6 hours. The dried bamboo fiber is further immersed in a silane coupling agent solution with a mass fraction of 0.5%-2% for 10-30 minutes and dried again, thereby forming a uniform coupling layer structure on the surface of the bamboo fiber, changing the surface of the bamboo fiber from hydrophilic to oleophilic, and improving its dispersion stability and interfacial bonding ability in the biodegradable polyester matrix.

[0037] The antibacterial agent is an inorganic antibacterial agent, preferably a silver-based or zinc-based antibacterial agent. The antibacterial agent exists in a carrier-loaded form, and the carrier is silicate or oxide particles. The average particle size of the antibacterial agent is 50-200 nm, and the mass fraction of active metal ions in the antibacterial agent is 0.5%-5%. The antibacterial agent is prepared by loading silver or zinc ions onto the surface of a porous silicate carrier, so that the active ingredient exists in a slow-release form and is uniformly dispersed in the matrix after the material is formed. The antibacterial agent forms a stable distribution structure inside the material and maintains a continuous antibacterial environment on the material surface through an ion slow-release mechanism, while controlling the migration rate of the active component to avoid performance degradation or precipitation risks during sterilization and long-term use.

[0038] The toughening agent is a thermoplastic elastomer, preferably a polyester elastomer or an olefin elastomer. The glass transition temperature of the toughening agent is -30℃ to 0℃, and the melt flow rate is 5 to 20 g / 10 min. During the melt blending process, the toughening agent is distributed in the biodegradable matrix as a dispersed phase, forming an elastic phase micro-region structure with a size of 0.5 to 3 μm. The elastic phase micro-regions deform and absorb energy under external force, thereby improving the impact toughness and crack resistance of the material, while avoiding the problem of increased brittleness caused by sterilization treatment.

[0039] The nucleating agent is an inorganic or organic nucleating agent, preferably talc or an organic small molecule nucleating agent. The particle size of the nucleating agent is 1-5 μm, and its distribution in the material is uniformly dispersed. The nucleating agent provides crystallization induction sites in the polylactic acid matrix, which increases the crystallization initiation temperature by 3-10°C and shortens the crystallization time, thereby forming a uniform and refined grain structure in the material during injection molding or injection stretch blow molding, improving the dimensional stability, transparency, and mechanical property consistency of the product.

[0040] Reference Figure 1 A method for preparing a bamboo fiber reinforced sterile biodegradable material, based on the above-mentioned bamboo fiber reinforced sterile biodegradable material, includes the following steps: S1. Directional surface modification treatment is applied to bamboo fiber to construct the structural basis for subsequent interfacial bonding; The bamboo fiber was modified according to the above preparation method, so that its surface changed from hydrophilic to a weakly polar structure compatible with the polyester matrix, thus providing conditions for subsequent interface construction.

[0041] S2. Based on the modified bamboo fiber obtained in S1, a compatibilizer is constructed and an interfacial bridging component is formed to achieve synergy in the multiphase system. The compatibilizer is prepared according to the above preparation method. The compatibilizer has both a nonpolar main chain and polar side groups in its molecular structure. It can interact with the polyester matrix and the surface of bamboo fiber respectively during the subsequent mixing process, thereby forming a continuous transition layer structure in the interface region and realizing continuous stress transmission.

[0042] S3. Based on the components obtained from S1 and S2, low-moisture-content premixing and dispersion are carried out to form a stable composite raw material system; Polylactic acid, poly(butylene adipate) / poly(dibutyl terephthalate), compatibilizer, bamboo fiber, bamboo powder, and toughening agent are added to a high-speed mixer and dry-mixed for 5–15 minutes at a speed of 300–800 r / min to achieve a preliminary uniform distribution of the components in a dry state. During the mixing process, the system temperature is controlled to not exceed 60℃ to avoid premature softening. Simultaneously, the bamboo powder is pre-dried (80–100℃, 2–4 h) to reduce its moisture content to below 2% to prevent the formation of bubbles or interface defects during subsequent melt processing. After this step, a uniformly dispersed composite premix with controlled moisture content is obtained, providing stable input conditions for melt blending.

[0043] S4. Based on the premix obtained in S3, perform melt blending and extrusion to construct a multiphase coupled microstructure system; The premixed material is fed into a twin-screw extruder for melt blending. The temperature range is set to 160–190℃, the screw speed is 100–300 r / min, and the material residence time in the barrel is 2–6 min. During the melting process, polylactic acid (PLA) and PBAT form a continuous phase structure, the toughening agent forms dispersed micro-regions (particle size 0.5–3 μm) under shearing, the compatibilizer migrates to the interface region to form an interface layer, and the bamboo fiber and bamboo powder form an oriented or semi-oriented distribution structure under shearing and dispersion. At the same time, antibacterial agents, antioxidants, and UV stabilizers are added to ensure uniform dispersion in the melt. After extrusion, the material is water-cooled, stretched, and pelletized to obtain composite material particles with a stable multiphase structure.

[0044] S5. Based on the composite material particles obtained in S4, perform drying and crystal structure regulation treatment to adapt to subsequent molding processes. The extruded granules are placed in a vacuum drying oven and dried at 60–80°C for 4–8 hours to reduce the moisture content of the granules to below 0.05%. During the drying process, the nucleating agent induces polylactic acid to undergo preliminary crystallization, forming a uniformly distributed microcrystalline nucleus structure, thereby accelerating the crystallization rate and improving the dimensional stability of the product during subsequent molding. The granules obtained in this step have good flowability and thermal stability and can be directly used for injection molding, injection stretch blow molding, or extrusion blow molding.

[0045] S6. Use the granules obtained in S5 to process containers to form biodegradable products with sterile properties; The dried composite material particles are added to an injection molding machine or blow molding equipment and molded under conditions of barrel temperature 160-190℃ and mold temperature 20-50℃. During the molding process, the multiphase structure inside the material is preserved, bamboo fiber forms a reinforcing skeleton structure, toughening agent forms energy absorption micro-regions, and antibacterial agent forms a uniform distribution inside the product. The molded container can be further sterilized with ethylene oxide or gamma rays. The material structure remains stable under sterilization conditions, thereby obtaining bamboo fiber reinforced container products with mechanical properties, sterility, and biodegradability.

[0046] Example 1: A bamboo fiber reinforced sterile biodegradable material comprises the following formulation: 50 parts polylactic acid; 10 parts poly(butylene adipate / terephthalate); 10 parts bamboo fiber; 5 parts bamboo powder; 2 parts compatibilizer; 5 parts toughening agent; 0.5 parts lubricant; 1 part flow aid; 0.2 parts antibacterial agent; 0.2 parts antioxidant; 0.1 parts UV stabilizer; 0.5 parts nucleating agent.

[0047] The compatibilizer is a maleic anhydride-grafted polylactic acid compatibilizer, wherein the grafting rate of maleic anhydride in the compatibilizer is 1.5%, and the number average molecular weight of the compatibilizer is 5 × 10⁻⁶. 4 The compatibilizer is prepared by the following method: polylactic acid and maleic anhydride are added to a twin-screw extruder at a mass ratio of 100:3 at 175°C, and a melt grafting reaction is carried out under the action of dicumyl peroxide initiator. The amount of initiator added is 0.5%, the reaction time is 6 min, and the compatibilizer is obtained by cooling and granulation.

[0048] The bamboo fiber is a short-cut bamboo fiber that has undergone surface modification treatment. The length of the bamboo fiber is 0.6 mm, the aspect ratio is 12, and the moisture content is controlled below 3%. The bamboo fiber is obtained by the following method: First, the raw bamboo fiber is placed in a 4% sodium hydroxide solution and soaked at 40°C for 60 min to remove surface lignin and impurities. Then, it is repeatedly washed with deionized water until neutral and dried at 95°C for 4 h. The dried bamboo fiber is further immersed in a 1% silane coupling agent solution for 20 min and dried again.

[0049] The antibacterial agent is a silver-based inorganic antibacterial agent, which exists in the form of a silicate carrier. The average particle size of the antibacterial agent is 120 nm, and the mass fraction of active silver ions in the antibacterial agent is 2.5%. The antibacterial agent is prepared by loading silver ions onto the surface of a porous silicate carrier, so that the active ingredient exists in a sustained-release form and is uniformly dispersed in the matrix after the material is formed.

[0050] The toughening agent is a polyester thermoplastic elastomer with a glass transition temperature of -15°C and a melt flow rate of 12 g / 10 min. During the melt blending process, the toughening agent is distributed in the biodegradable matrix as a dispersed phase, forming an elastic phase micro-region structure with a size of 1.5 μm.

[0051] The nucleating agent is talc powder, the particle size of which is 3 μm, and its distribution in the material is uniformly dispersed.

[0052] The preparation of the above-mentioned bamboo fiber reinforced sterile biodegradable material includes the following steps: S1. Directional surface modification treatment is applied to bamboo fiber to construct the structural basis for subsequent interfacial bonding; The bamboo fiber was modified according to the above preparation method, so that its surface changed from hydrophilic to a weakly polar structure compatible with the polyester matrix.

[0053] S2. Based on the modified bamboo fiber obtained in S1, a compatibilizer is constructed and an interfacial bridging component is formed to achieve synergy in the multiphase system. The compatibilizer was prepared according to the above preparation method. The compatibilizer has both a nonpolar main chain and polar side groups in its molecular structure, which can interact with the polyester matrix and the surface of bamboo fiber respectively during the subsequent mixing process.

[0054] S3. Based on the components obtained from S1 and S2, low-moisture-content premixing and dispersion are carried out to form a stable composite raw material system; Polylactic acid, polybutylene adipate / terephthalate, compatibilizer, bamboo fiber, bamboo powder, and toughening agent were added to a high-speed mixer and dry-mixed for 10 minutes at a speed of 550 r / min to allow the components to form a preliminary uniform distribution in a dry state. During the mixing process, the system temperature was controlled not to exceed 60℃ to avoid premature softening. At the same time, the bamboo powder was pre-dried (90℃, 3h) to reduce its moisture content to less than 2% to prevent the generation of bubbles or interface defects during subsequent melt processing.

[0055] S4. Based on the premix obtained in S3, perform melt blending and extrusion to construct a multiphase coupled microstructure system; The premixed material was fed into a twin-screw extruder for melt blending. The temperature was set at 175℃, the screw speed at 200 r / min, and the material residence time in the barrel was 4 min. During the melting process, polylactic acid (PLA) and PBAT formed a continuous phase structure, the toughening agent formed dispersed phase micro-regions (particle size 1.5 μm) under shearing, the compatibilizer migrated to the interface region to form an interface layer, and the bamboo fiber and bamboo powder formed an oriented or semi-oriented distribution structure under shearing and dispersion. At the same time, antibacterial agents, antioxidants, and UV stabilizers were added to ensure uniform dispersion in the melt. After extrusion, the material was water-cooled, stretched, and pelletized to obtain composite material particles with a stable multiphase structure.

[0056] S5. Based on the composite material particles obtained in S4, perform drying and crystal structure regulation treatment to adapt to subsequent molding processes. The extruded granules were placed in a vacuum drying oven and dried at 70°C for 6 hours to reduce the moisture content of the granules to below 0.05%. During the drying process, the nucleating agent induced polylactic acid to undergo preliminary crystallization, forming a uniformly distributed microcrystalline nucleus structure.

[0057] S6. Use the granules obtained in S5 to process containers to form biodegradable products with sterile properties; The dried composite material particles are added to an injection molding machine or blow molding equipment and processed under the conditions of barrel temperature 175℃ and mold temperature 35℃. During the molding process, the multiphase structure inside the material is preserved, bamboo fiber forms a reinforcing skeleton structure, toughening agent forms energy absorption micro-regions, and antibacterial agent forms a uniform distribution inside the product.

[0058] Example 2: A bamboo fiber reinforced sterile biodegradable material comprises the following formulation: Polylactic acid 65 parts; poly(butylene adipate / terephthalate) 20 parts; bamboo fiber 17.5 parts; bamboo powder 10 parts; compatibilizer 4 parts; toughening agent 8.5 parts; lubricant 1.25 parts; flow aid 2.5 parts; antibacterial agent 0.6 parts; antioxidant 0.5 parts; UV stabilizer 0.3 parts; nucleating agent 1.25 parts.

[0059] The compatibilizer is a maleic anhydride-grafted polylactic acid compatibilizer, wherein the grafting rate of maleic anhydride in the compatibilizer is 1.5%, and the number average molecular weight of the compatibilizer is 5 × 10⁻⁶. 4 The compatibilizer is prepared by the following method: polylactic acid and maleic anhydride are added to a twin-screw extruder at a mass ratio of 100:3 at 175°C, and a melt grafting reaction is carried out under the action of dicumyl peroxide initiator. The amount of initiator added is 0.5%, the reaction time is 6 min, and the compatibilizer is obtained by cooling and granulation.

[0060] The bamboo fiber is a short-cut bamboo fiber that has undergone surface modification treatment. The length of the bamboo fiber is 0.6 mm, the aspect ratio is 12, and the moisture content is controlled below 3%. The bamboo fiber is obtained by the following method: First, the raw bamboo fiber is placed in a 4% sodium hydroxide solution and soaked at 40°C for 60 min to remove surface lignin and impurities. Then, it is repeatedly washed with deionized water until neutral and dried at 95°C for 4 h. The dried bamboo fiber is further immersed in a 1% silane coupling agent solution for 20 min and dried again.

[0061] The antibacterial agent is a silver-based inorganic antibacterial agent, which exists in the form of a silicate carrier. The average particle size of the antibacterial agent is 120 nm, and the mass fraction of active silver ions in the antibacterial agent is 2.5%. The antibacterial agent is prepared by loading silver ions onto the surface of a porous silicate carrier, so that the active ingredient exists in a sustained-release form and is uniformly dispersed in the matrix after the material is formed.

[0062] The toughening agent is a polyester thermoplastic elastomer with a glass transition temperature of -15°C and a melt flow rate of 12 g / 10 min. During the melt blending process, the toughening agent is distributed in the biodegradable matrix as a dispersed phase, forming an elastic phase micro-region structure with a size of 1.5 μm.

[0063] The nucleating agent is talc powder, the particle size of which is 3 μm, and its distribution in the material is uniformly dispersed.

[0064] The preparation of the above-mentioned bamboo fiber reinforced sterile biodegradable material includes the following steps: S1. Directional surface modification treatment is applied to bamboo fiber to construct the structural basis for subsequent interfacial bonding; The bamboo fiber was modified according to the above preparation method, so that its surface changed from hydrophilic to a weakly polar structure compatible with the polyester matrix.

[0065] S2. Based on the modified bamboo fiber obtained in S1, a compatibilizer is constructed and an interfacial bridging component is formed to achieve synergy in the multiphase system. The compatibilizer was prepared according to the above preparation method. The compatibilizer has both a nonpolar main chain and polar side groups in its molecular structure, which can interact with the polyester matrix and the surface of bamboo fiber respectively during the subsequent mixing process.

[0066] S3. Based on the components obtained from S1 and S2, low-moisture-content premixing and dispersion are carried out to form a stable composite raw material system; Polylactic acid, polybutylene adipate / terephthalate, compatibilizer, bamboo fiber, bamboo powder, and toughening agent were added to a high-speed mixer and dry-mixed for 10 minutes at a speed of 550 r / min to allow the components to form a preliminary uniform distribution in a dry state. During the mixing process, the system temperature was controlled not to exceed 60℃ to avoid premature softening. At the same time, the bamboo powder was pre-dried (90℃, 3h) to reduce its moisture content to less than 2% to prevent the generation of bubbles or interface defects during subsequent melt processing.

[0067] S4. Based on the premix obtained in S3, perform melt blending and extrusion to construct a multiphase coupled microstructure system; The premixed material was fed into a twin-screw extruder for melt blending. The temperature was set at 175℃, the screw speed at 200 r / min, and the material residence time in the barrel was 4 min. During the melting process, polylactic acid (PLA) and PBAT formed a continuous phase structure, the toughening agent formed dispersed phase micro-regions (particle size 1.5 μm) under shearing, the compatibilizer migrated to the interface region to form an interface layer, and the bamboo fiber and bamboo powder formed an oriented or semi-oriented distribution structure under shearing and dispersion. At the same time, antibacterial agents, antioxidants, and UV stabilizers were added to ensure uniform dispersion in the melt. After extrusion, the material was water-cooled, stretched, and pelletized to obtain composite material particles with a stable multiphase structure.

[0068] S5. Based on the composite material particles obtained in S4, perform drying and crystal structure regulation treatment to adapt to subsequent molding processes. The extruded granules were placed in a vacuum drying oven and dried at 70°C for 6 hours to reduce the moisture content of the granules to below 0.05%. During the drying process, the nucleating agent induced polylactic acid to undergo preliminary crystallization, forming a uniformly distributed microcrystalline nucleus structure.

[0069] S6. Use the granules obtained in S5 to process containers to form biodegradable products with sterile properties; The dried composite material particles are added to an injection molding machine or blow molding equipment and processed under the conditions of barrel temperature 175℃ and mold temperature 35℃. During the molding process, the multiphase structure inside the material is preserved, bamboo fiber forms a reinforcing skeleton structure, toughening agent forms energy absorption micro-regions, and antibacterial agent forms a uniform distribution inside the product.

[0070] Example 3: A bamboo fiber reinforced sterile biodegradable material comprises the following formulation: 80 parts polylactic acid; 30 parts poly(butylene adipate / terephthalate); 25 parts bamboo fiber; 15 parts bamboo powder; 6 parts compatibilizer; 12 parts toughening agent; 2 parts lubricant; 4 parts flow aid; 1 part antibacterial agent; 0.8 parts antioxidant; 0.5 parts UV stabilizer; 2 parts nucleating agent.

[0071] The compatibilizer is a maleic anhydride-grafted polylactic acid compatibilizer, wherein the grafting rate of maleic anhydride in the compatibilizer is 1.5%, and the number average molecular weight of the compatibilizer is 5 × 10⁻⁶. 4 The compatibilizer is prepared by the following method: polylactic acid and maleic anhydride are added to a twin-screw extruder at a mass ratio of 100:3 at 175°C, and a melt grafting reaction is carried out under the action of dicumyl peroxide initiator. The amount of initiator added is 0.5%, the reaction time is 6 min, and the compatibilizer is obtained by cooling and granulation.

[0072] The bamboo fiber is a short-cut bamboo fiber that has undergone surface modification treatment. The length of the bamboo fiber is 0.6 mm, the aspect ratio is 12, and the moisture content is controlled below 3%. The bamboo fiber is obtained by the following method: First, the raw bamboo fiber is placed in a 4% sodium hydroxide solution and soaked at 40°C for 60 min to remove surface lignin and impurities. Then, it is repeatedly washed with deionized water until neutral and dried at 95°C for 4 h. The dried bamboo fiber is further immersed in a 1% silane coupling agent solution for 20 min and dried again.

[0073] The antibacterial agent is a silver-based inorganic antibacterial agent, which exists in the form of a silicate carrier. The average particle size of the antibacterial agent is 120 nm, and the mass fraction of active silver ions in the antibacterial agent is 2.5%. The antibacterial agent is prepared by loading silver ions onto the surface of a porous silicate carrier, so that the active ingredient exists in a sustained-release form and is uniformly dispersed in the matrix after the material is formed.

[0074] The toughening agent is a polyester thermoplastic elastomer with a glass transition temperature of -15°C and a melt flow rate of 12 g / 10 min. During the melt blending process, the toughening agent is distributed in the biodegradable matrix as a dispersed phase, forming an elastic phase micro-region structure with a size of 1.5 μm.

[0075] The nucleating agent is talc powder, the particle size of which is 3 μm, and its distribution in the material is uniformly dispersed.

[0076] The preparation of the above-mentioned bamboo fiber reinforced sterile biodegradable material includes the following steps: S1. Directional surface modification treatment is applied to bamboo fiber to construct the structural basis for subsequent interfacial bonding; The bamboo fiber was modified according to the above preparation method, so that its surface changed from hydrophilic to a weakly polar structure compatible with the polyester matrix.

[0077] S2. Based on the modified bamboo fiber obtained in S1, a compatibilizer is constructed and an interfacial bridging component is formed to achieve synergy in the multiphase system. The compatibilizer was prepared according to the above preparation method. The compatibilizer has both a nonpolar main chain and polar side groups in its molecular structure, which can interact with the polyester matrix and the surface of bamboo fiber respectively during the subsequent mixing process.

[0078] S3. Based on the components obtained from S1 and S2, low-moisture-content premixing and dispersion are carried out to form a stable composite raw material system; Polylactic acid, polybutylene adipate / terephthalate, compatibilizer, bamboo fiber, bamboo powder, and toughening agent were added to a high-speed mixer and dry-mixed for 10 minutes at a speed of 550 r / min to allow the components to form a preliminary uniform distribution in a dry state. During the mixing process, the system temperature was controlled not to exceed 60℃ to avoid premature softening. At the same time, the bamboo powder was pre-dried (90℃, 3h) to reduce its moisture content to less than 2% to prevent the generation of bubbles or interface defects during subsequent melt processing.

[0079] S4. Based on the premix obtained in S3, perform melt blending and extrusion to construct a multiphase coupled microstructure system; The premixed material was fed into a twin-screw extruder for melt blending. The temperature was set at 175℃, the screw speed at 200 r / min, and the material residence time in the barrel was 4 min. During the melting process, polylactic acid (PLA) and PBAT formed a continuous phase structure, the toughening agent formed dispersed phase micro-regions (particle size 1.5 μm) under shearing, the compatibilizer migrated to the interface region to form an interface layer, and the bamboo fiber and bamboo powder formed an oriented or semi-oriented distribution structure under shearing and dispersion. At the same time, antibacterial agents, antioxidants, and UV stabilizers were added to ensure uniform dispersion in the melt. After extrusion, the material was water-cooled, stretched, and pelletized to obtain composite material particles with a stable multiphase structure.

[0080] S5. Based on the composite material particles obtained in S4, perform drying and crystal structure regulation treatment to adapt to subsequent molding processes. The extruded granules were placed in a vacuum drying oven and dried at 70°C for 6 hours to reduce the moisture content of the granules to below 0.05%. During the drying process, the nucleating agent induced polylactic acid to undergo preliminary crystallization, forming a uniformly distributed microcrystalline nucleus structure.

[0081] S6. Use the granules obtained in S5 to process containers to form biodegradable products with sterile properties; The dried composite material particles are added to an injection molding machine or blow molding equipment and processed under the conditions of barrel temperature 175℃ and mold temperature 35℃. During the molding process, the multiphase structure inside the material is preserved, bamboo fiber forms a reinforcing skeleton structure, toughening agent forms energy absorption micro-regions, and antibacterial agent forms a uniform distribution inside the product.

[0082] Comparative Example 1: The formulation system is basically the same as that in Example 2, but without the addition of a compatibilizer, including: Polylactic acid 65 parts; poly(butylene adipate / terephthalate) 20 parts; bamboo fiber 17.5 parts; bamboo powder 10 parts; toughening agent 8.5 parts; lubricant 1.25 parts; flow aid 2.5 parts; antibacterial agent 0.6 parts; antioxidant 0.5 parts; UV stabilizer 0.3 parts; nucleating agent 1.25 parts.

[0083] This comparative example is mainly used to verify the effects of compatibilizer on the interfacial bonding, mechanical properties, and molding stability of bamboo fiber / bamboo powder and biodegradable matrix.

[0084] Comparative Example 2: The formulation system is basically the same as that in Example 2, but without the addition of antibacterial agents, including: Polylactic acid 65 parts; polybutylene adipate / terephthalate 20 parts; bamboo fiber 17.5 parts; bamboo powder 10 parts; compatibilizer 4 parts; toughening agent 8.5 parts; lubricant 1.25 parts; flow aid 2.5 parts; antioxidant 0.5 parts; UV stabilizer 0.3 parts; nucleating agent 1.25 parts.

[0085] This comparative example is mainly used to verify the effects of antimicrobial agents on the antibacterial ability of the material itself, the surface condition after sterilization, and the suitability for biopharmaceutical packaging.

[0086] The materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to the tests shown in Table 1 below to verify the actual effect of the coating.

[0087] Table 1

[0088] Note: If used for containers that come into direct contact with the drug solution, additional validation items such as total migration, specific migration, aseptic maintenance, seal integrity, and performance retention after accelerated aging need to be added to the above items.

[0089] Summary of comprehensive tests for Examples 1-3: Examples 1-3 all exhibited good overall performance balance. As the amount of bamboo fiber and bamboo powder added increased, the rigidity and dimensional stability of the material gradually improved. Under the synergistic effect of the compatibilizer and toughening agent, no significant embrittlement was observed. In Example 1, due to the low content of reinforcing components, the material had good overall fluidity, making it suitable for molding complex structural containers, but its rigidity and pressure resistance were relatively weak. In Example 2, with the components in the middle range, the material achieved a better balance between tensile strength, impact toughness, and molding stability. The interface structure was uniform, and no obvious interface debonding or fiber agglomeration was observed, resulting in the most stable overall performance. In Example 3, the higher content of bamboo fiber and bamboo powder significantly enhanced the material's rigidity and resistance to deformation. While maintaining good interfacial bonding under the action of the compatibilizer, the higher filler ratio led to a decrease in melt fluidity, increasing the requirements for the molding process window. Overall, no obvious bubbles, delamination, or cracking defects were observed in any of the three examples, indicating that the formulation system possesses good processability and structural stability in its structural design.

[0090] The performance of the embodiments in terms of interface bonding and structural stability: Observation of cross-sectional morphology and analysis of mechanical failure modes revealed that a continuous transitional interface layer was formed between the bamboo fiber and the matrix in Examples 1-3. The fiber pull-out length was short, and the interface adhesion was tight, indicating that the compatibilizer effectively played its interfacial bridging role. In particular, in Examples 2 and 3, the fiber and matrix exhibited an "embedded bonding" state, with no obvious pores or interface crack propagation paths, thus enabling effective stress transfer and dispersion under external force. In contrast, after repeated thermal cycling and sterilization treatment, the interfacial structure remained stable, with no obvious interfacial delamination or performance degradation, indicating that the system exhibits good performance in terms of thermal stability and interfacial durability.

[0091] The performance of the examples in terms of sterilization stability: After sterilization with ethylene oxide or gamma rays, the materials in Examples 1-3 showed no obvious yellowing, brittleness, or deformation, and their mechanical properties remained stable. This indicates that the antioxidants and UV stabilizers effectively inhibited molecular chain degradation and oxidation reactions in the system. Simultaneously, the materials exhibited minimal dimensional changes before and after sterilization, with no significant shrinkage or warping, demonstrating that the nucleating agent effectively improved the dimensional stability of the material by regulating the crystal structure. In Example 2, in particular, due to the harmonious proportions of the components, the performance changes before and after sterilization were minimal, exhibiting superior compatibility with medical containers.

[0092] The performance of the examples in terms of antibacterial properties: Examples 1-3 all exhibited stable antibacterial ability, with no obvious signs of microbial attachment or proliferation on the material surface, indicating that the antibacterial agent was uniformly dispersed in the matrix and could continuously release active ingredients. After long-term storage and sterilization, the antibacterial effect did not show significant attenuation, indicating that the antibacterial agent existed in a stable form in the system without significant migration or inactivation. Examples 2 and 3, due to their higher antibacterial agent content, showed more pronounced antibacterial persistence, making them suitable for biomedical container applications with high aseptic requirements.

[0093] Summary of tests for Comparative Example 1 (without compatibilizer): Comparative Example 1 exhibited significant interfacial instability during preparation and molding. There was obvious delamination and porous structure between the bamboo fiber and the matrix. Cross-sectional observation showed that the fiber pull-out length was relatively long and the interfacial bonding was loose. In mechanical property testing, the material was prone to brittle fracture and its impact performance was significantly reduced. At the same time, after sterilization, the interfacial defects were further expanded, and local crack propagation was observed. This indicates that without a compatibilizer, it is difficult to form an effective interfacial structure between the bamboo fiber and the biodegradable matrix, which seriously affects the overall performance and stability of the material.

[0094] Summary of tests for Comparative Example 2 (without antibacterial agent): Comparative Example 2 is similar to Example 2 in terms of mechanical and molding properties, but it did not show effective antibacterial ability in the antibacterial performance test, and microorganisms easily adhered to the material surface during storage. In addition, although the material maintained structural integrity after sterilization, it lacked sustained antibacterial ability and could not meet the requirements of biomedical containers for a long-term sterile environment. These results indicate that post-treatment sterilization alone cannot replace the antibacterial system of the material itself, and antibacterial agents play a key role in achieving sterility in this material system.

[0095] Overall conclusion: The comparison between the examples and the comparative examples shows that the compatibilizer plays a decisive role in the stability of the interface structure, while the antibacterial agent plays a key role in the sterility of the material. The absence of either one will lead to obvious defects in the corresponding performance dimensions of the material. The present invention achieves synergistic optimization of the material in terms of mechanical properties, interface stability, sterilization adaptability and antibacterial properties through multi-component synergistic design, which can meet the application requirements of biomedical containers for multi-performance coupling.

[0096] It should be noted that 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 preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A bamboo fiber reinforced sterile and biodegradable material, characterized in that, The material comprises the following formula by weight: Polylactic acid 50-80 parts; 10-30 parts of poly(butylene adipate / terephthalate); 10-25 parts bamboo fiber; Bamboo powder 5-15 parts; 2-6 parts compatibilizer; 5-12 parts toughening agent; Lubricant 0.5 to 2 parts; 1-4 parts of flow aid; Antibacterial agent 0.2-1 part; Antioxidant 0.2–0.8 parts; 0.1 to 0.5 parts of UV stabilizer; Nucleating agent 0.5 to 2 parts.

2. The bamboo fiber reinforced sterile biodegradable material according to claim 1, characterized in that, The bamboo fiber is a short-cut bamboo fiber that has undergone surface modification treatment. The length of the bamboo fiber is 0.2 to 1 mm, the aspect ratio is 5 to 20, and the moisture content is controlled below 3%.

3. The bamboo fiber reinforced sterile biodegradable material according to claim 2, characterized in that, The bamboo fiber is obtained by the following process: First, place the bamboo fiber in a sodium hydroxide solution with a mass concentration of 2% to 6% and soak it for 30 to 90 minutes at room temperature to 60°C to remove surface lignin and impurities. The bamboo fibers were then repeatedly washed with deionized water until neutral and dried at 80–110°C for 2–6 hours. The dried bamboo fibers were then immersed in a 0.5%–2% silane coupling agent solution for 10–30 minutes and dried again to form a uniform coupling layer structure on the surface of the bamboo fibers, thus changing the surface of the bamboo fibers from hydrophilic to oleophilic.

4. The bamboo fiber reinforced sterile biodegradable material according to claim 1, characterized in that, The compatibilizer is a maleic anhydride-grafted polyester compatibilizer, wherein the grafting rate of maleic anhydride in the compatibilizer is 0.5% to 2.5%, and the number average molecular weight of the compatibilizer is 2 × 10⁻⁶. 4 ~8×10 4 .

5. The bamboo fiber reinforced sterile biodegradable material according to claim 4, characterized in that, The compatibilizer is prepared by the following method: Polylactic acid and maleic anhydride were fed into a twin-screw extruder at a mass ratio of 100:1 to 5 at 160–190°C, and a melt grafting reaction was carried out under the action of a peroxide initiator. The amount of the peroxide initiator added is 0.2% to 0.8%, the reaction time is 3 to 10 min, and the compatibilizer is obtained by cooling and granulation.

6. The bamboo fiber reinforced sterile biodegradable material according to claim 1, characterized in that, The antibacterial agent is an inorganic antibacterial agent, including silver-based or zinc-based antibacterial agents. The antibacterial agent exists in a carrier-loaded form, and the carrier is silicate or oxide particles. The average particle size of the antibacterial agent is 50-200 nm, and the mass fraction of active metal ions in the antibacterial agent is 0.5%-5%. The antibacterial agent is prepared by loading silver ions or zinc ions onto the surface of a porous silicate carrier.

7. The bamboo fiber reinforced sterile biodegradable material according to claim 1, characterized in that, The toughening agent is a thermoplastic elastomer, including polyester elastomers or olefin elastomers. The glass transition temperature of the toughening agent is -30℃ to 0℃, and the melt flow rate is 5 to 20 g / 10 min. The toughening agent is distributed in the biodegradable matrix as a dispersed phase during melt blending, forming an elastic phase micro-region structure with a size of 0.5 to 3 μm.

8. The bamboo fiber reinforced sterile biodegradable material according to claim 1, characterized in that, The nucleating agent is an inorganic nucleating agent or an organic nucleating agent, including talc or organic small molecule nucleating agents. The particle size of the nucleating agent is 1 to 5 μm, and its distribution in the material is uniformly dispersed. The nucleating agent provides crystallization induction sites in the polylactic acid matrix, increasing the crystallization initiation temperature by 3-10°C and shortening the crystallization time, thereby enabling the material to form a uniform and refined grain structure during injection molding or injection stretch blow molding.

9. The bamboo fiber reinforced sterile biodegradable material according to claim 1, characterized in that, The polylactic acid and poly(butylene adipate / terephthalate) form a biodegradable matrix system; The bamboo fiber and bamboo powder constitute a synergistic reinforcing and filling system; The compatibilizer is used to improve the interfacial bonding performance between the biodegradable matrix system and the synergistic reinforcing filler system; The antibacterial agent, antioxidant, and UV stabilizer constitute a sterile stabilization auxiliary system, which is used to improve the structural stability and antibacterial properties of the material under sterilization conditions.

10. A method for preparing a bamboo fiber reinforced sterile biodegradable material, comprising preparing the material based on the bamboo fiber reinforced sterile biodegradable material according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Directional surface modification treatment is applied to bamboo fiber to construct the structural basis for subsequent interfacial bonding; S2. Based on the modified bamboo fiber obtained in S1, a compatibilizer is constructed and an interfacial bridging component is formed to achieve synergy in the multiphase system. S3. Based on the components obtained from S1 and S2, low-moisture-content premixing and dispersion are carried out to form a stable composite raw material system; S4. Based on the premix obtained in S3, perform melt blending and extrusion to construct a multiphase coupled microstructure system; S5. Based on the composite material particles obtained in S4, perform drying and crystal structure regulation treatment to adapt to subsequent molding processes. S6. Use the particles obtained in S5 to process containers to form biodegradable products with sterile properties.

Images