Preparation method and application of full-biodegradable composite material with high bamboo fiber content

Abstract

The invention discloses a preparation method and application of a full-biodegradable composite material with high bamboo fiber content, the composite material is prepared from a degradable resin matrix, fine bamboo powder, inorganic mineral filler, an interface modifier and a processing aid, the mesh number of the fine bamboo powder is 100-1200, and the filling amount can reach 60%. According to the invention, a reverse coating two-step process based on a continuous mixing technology is adopted: firstly, a melting additive is used for preferentially wetting bamboo powder to form a microcosmic skin-core structure master batch, and then dilution and reactive compatibilization are carried out through twin-screw extrusion. The calcium sulfate whiskers and the bamboo powder are introduced to construct a microscopic synergistic framework, and a double-peak particle size compounding technology is adopted, so that the problems that the high-content bamboo powder is difficult to disperse, easy to agglomerate and poor in processing fluidity in hydrophobic resin are effectively solved. The prepared material is low in cost and completely biodegradable, has high rigidity and high toughness, and is suitable for the fields of film blow molding, injection molding, sheet extrusion and the like.

Description

Technical Field

[0001] This invention relates to the field of bio-based new material preparation and biodegradable material application technology, specifically to a method for preparing and applying a fully biodegradable composite material with high bamboo fiber content. Background Technology

[0002] With the implementation of global "plastic ban / restriction" policies and the increasing awareness of environmental protection, the "white pollution" and microplastic problems caused by traditional petroleum-based plastics are becoming increasingly serious. my country has clearly proposed a development strategy of "replacing plastic with bamboo," encouraging the development of biomaterials to replace traditional plastics. While fully biodegradable resins such as polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) are environmentally friendly, their high production costs and limited mechanical properties restrict their large-scale promotion. Filling biodegradable resins with widely available and renewable bamboo powder is an effective way to reduce costs and give materials a natural texture.

[0003] However, existing technologies still have many shortcomings in preparing composite materials with high bamboo powder content: First, existing technologies mostly use bamboo powder with a relatively coarse particle size (e.g., 40-200 mesh), which results in a rough material surface, making it unsuitable for applications requiring high smoothness, such as film blow molding or precision injection molding; Second, in pursuit of low cost, some existing solutions mix bamboo powder with non-degradable plastics such as polypropylene (PP). Although this improves mechanical properties, it does not truly solve the problem of microplastic residues and is not a fully biodegradable material; Third, bamboo powder is a strongly polar hydrophilic material with poor interfacial compatibility with hydrophobic degradable resins. Existing technologies usually require complex chemical grafting pretreatment of bamboo powder, resulting in a long and costly process; Finally, at high filler contents (e.g., exceeding 30%), bamboo powder is prone to agglomeration in the matrix, leading to brittle materials and a sharp decrease in processing fluidity. Furthermore, existing modification systems are often only applicable to a single resin (e.g., only PLA), lacking universality for multiple matrices such as PBAT, PBS, and PPC, making it difficult to meet the diverse application needs of flexible films and sheets. Summary of the Invention

[0004] To address the technical problems of low bamboo powder content, poor dispersion, weak interfacial bonding, and easy degradation during processing in existing biodegradable plastics, this invention provides a method for preparing and applying a fully biodegradable composite material with high bamboo fiber content. This invention achieves efficient dispersion and reinforcement of bamboo powder through ultrafine powder modification, whisker synergistic reinforcement, and core-sheath structure coating processes, reducing material costs and expanding its applications in films, injection molding, and sheets.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A fully biodegradable composite material with high bamboo fiber content is prepared from the following components in parts by weight: 15-80 parts of biodegradable resin matrix, 5-60 parts of fine bamboo powder, 0-35 parts of inorganic mineral filler, 0.5-5 parts of interface modifier, and 0.1-2 parts of processing aid; wherein the fine bamboo powder has a particle size of 100-1200 mesh and is uniformly dispersed in the biodegradable resin matrix.

[0006] Furthermore, the inorganic mineral filler includes calcium sulfate whiskers; the median particle size D50 of the fine bamboo powder and the average length L of the calcium sulfate whiskers satisfy the following relationship: L≥2×D50; the calcium sulfate whiskers form a microscopic support framework in the biodegradable resin matrix, and the fine bamboo powder fills the voids in the microscopic support framework.

[0007] Furthermore, the fine bamboo powder has a multi-level particle size composite structure, including a first particle size component and a second particle size component; The first particle size component has a mesh size of 100-500 mesh and accounts for 60%-80% of the total weight of the fine bamboo powder; The second particle size component has a mesh size of 800-1200 mesh and accounts for 20%-40% of the total weight of the fine bamboo powder.

[0008] Further, the biodegradable resin matrix is ​​selected from one or more of polylactic acid PLA, polybutylene adipate / terephthalate PBAT, polybutylene succinate PBS, polybutylene succinate-adipate PBSA, polyhydroxyalkanoate PHA, polypropylene carbonate PPC, and polyhydroxybutyrate PHB. The interface modifier is selected from one or a combination of titanate coupling agents, aluminate coupling agents, silane coupling agents, maleic anhydride graft polymers, and epoxy coupling agents.

[0009] Furthermore, the microstructure of the composite material exhibits a core-skin structure; the core-skin structure is characterized by: The core layer is made of fine bamboo powder, and the surface of the core layer is covered with an intermediate layer formed by the processing aid. The intermediate layer is covered with a skin layer formed by a portion of the biodegradable resin matrix.

[0010] The present invention also provides a method for preparing the above-mentioned composite material, comprising the following steps: Step S1, Pretreatment: The fine bamboo powder is subjected to high-speed shearing (2000-3000 rpm) under heating conditions of 100-115℃, and a liquid interface modifier is sprayed to reduce the moisture content to below 0.5% to obtain activated bamboo powder.

[0011] Step S2, Preparation of high-filler masterbatch (two-step core): Activated bamboo powder, inorganic mineral filler, processing aids and part of biodegradable resin matrix are put into a mixing equipment for blending, and then extruded and granulated to obtain a high-filler masterbatch with a bamboo powder content of 40%-70%.

[0012] Optimal process: The reverse feeding sequence based on continuous internal mixing technology is adopted, that is, the additives are added first to melt with the resin to form a liquid carrier, and then bamboo powder is added. The melt preferentially wets and coats the surface of the bamboo powder, and the strong shearing action of the continuous internal mixer is used to achieve efficient dispersion.

[0013] Step S3, Dilution Molding: The high-filler masterbatch is mixed with the remaining resin matrix and melt-plasticized using a twin-screw extruder or injection molding machine. During this process, a multifunctional chain extender (such as an epoxy chain extender) can be introduced through the side feed port for reactive extrusion, thereby constructing in-situ chemical bonds between bamboo powder and resin.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: By employing a reverse coating masterbatch preparation process based on continuous mixing technology and constructing a micro-core structure, uniform dispersion and efficient wetting of fine bamboo powder (up to 1200 mesh) in a hydrophobic resin matrix were achieved. This successfully increased the bamboo powder filling amount to 60% while ensuring the material's processing fluidity and mechanical properties, significantly reducing the raw material cost of fully biodegradable materials and solving the problem of powder agglomeration under high filling amounts. Furthermore, this invention introduces calcium sulfate whiskers to construct a micro-rigid support framework and controls the specific matching relationship between whisker length and bamboo powder particle size (L≥2×D50), achieving a synergistic effect of whisker reinforcement and bamboo powder filling. This significantly improves the tensile strength and flexural modulus of the composite material, overcoming the defect of traditional high-filling biomass materials being prone to brittleness. Meanwhile, through the synergistic effect of reactive extrusion technology and multi-chain extension system, a strong chemical bond is achieved between bamboo powder and various biodegradable resins, including PLA, PBAT, PBS, and PPC. This endows the material with excellent comprehensive mechanical properties and broad processing versatility, enabling it to meet the application needs of different fields, from soft films to rigid injection molded parts. Moreover, the product is completely degradable after use, truly realizing the environmentally friendly and pollution-free replacement of plastics with bamboo. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0016] Figure 1 This is a process flow diagram for preparing the high bamboo fiber content fully biodegradable composite material of the present invention; Figure 2This is a schematic diagram of the microstructure of the bamboo powder masterbatch in an embodiment of the present invention; Figure 3 This is a schematic diagram of the microscopic support framework constructed by calcium sulfate whiskers and fine bamboo powder in an embodiment of the present invention; Figure 4 This is a schematic diagram of the stacking structure of bamboo powder with bimodal particle size distribution in a film in an embodiment of the present invention.

[0017] In the figure: 1. Fine bamboo powder; 2. Intermediate layer; 3. Biodegradable resin matrix; 4. Calcium sulfate whiskers; 5. Fine bamboo powder particles; 6. Resin matrix; 7. Film surface; 8. Large-diameter bamboo powder; 9. Small-diameter bamboo powder. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0019] It should be noted that the specific descriptions of some commercially available raw materials used in the embodiments of this invention are as follows (the CAS numbers and chemical names below are for reference only, and the actual procurement shall prevail): Silane coupling agent KH550: Chemical name is 3-aminopropyltriethoxysilane {CAS: 919-30-2}.

[0020] Silane coupling agent KH560: Chemical name is γ-(2,3-epoxypropoxy)propyltrimethoxysilane {CAS:2530-83-8}.

[0021] Silane coupling agent KH570: Chemical name is 3-methacryloyloxypropyltrimethoxysilane {CAS:2530-85-0}.

[0022] Compatibilizer Xibond 250: The main component is styrene-maleic anhydride random copolymer (SMA) {CAS:26762-29-8}, purchased from Polyscope.

[0023] Chain extender ADR 4468: refers to a multifunctional epoxy chain extender (styrene-acrylic epoxy functionalized copolymer), purchased from BASF.

[0024] Compatibilizer AX8900: The main component is ethylene-methyl acrylate-glycidyl methacrylate terpolymer (E-MA-GMA), purchased from Arkema.

[0025] Antioxidant 1010: Chemical name is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] ester {CAS: 6683-19-8}.

[0026] Antioxidant 1076: Chemical name is β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester {CAS: 2082-79-3}.

[0027] Lubricant EBS: Chemical name is N,N'-ethylene bis-stearamide {CAS: 110-30-5}.

[0028] Lubricant PETS: Chemical name is pentaerythritol stearate {CAS: 115-83-3}.

[0029] Mesh count explanation: In this invention, "mesh" refers to the Taylor standard sieve mesh count.

[0030] The high bamboo fiber content fully biodegradable composite material described in this invention is prepared by a process that is mainly divided into a one-step twin-screw extrusion process and a two-step continuous mixing masterbatch process, depending on the amount of bamboo powder filling. In the following examples, the "fine bamboo powder" is dried to a moisture content of less than 0.5%.

[0031] Example 1 This embodiment prepares a composite material suitable for injection molded products. The formulation consists of: 10 parts of 100-mesh fine bamboo powder, 10 parts of 1000-mesh calcium carbonate, 70 parts of polylactic acid (PLA), 7 parts of polybutylene succinate (PBS); and 1 part of silane coupling agent KH560, 1 part of compatibilizer Xibond 250, 0.2 parts of antioxidant 1010, 0.5 parts of lubricant EBS, and 0.3 parts of dispersant PEG 4000.

[0032] Preparation process: A one-step twin-screw extrusion process is used. The above components are mixed evenly in a high-speed mixer and then fed into a twin-screw extruder. The extruder temperature is set to 150℃-170℃, utilizing the shear heat of the screw to activate the coupling agent in situ on the surface of the bamboo powder. This formulation has a low bamboo powder content and is mainly used as a reinforcing filler. The resulting particles have a smooth surface and good flowability, making them suitable for producing injection-molded products such as disposable cutlery and stationery.

[0033] Example 2 This embodiment prepares a biodegradable film material with excellent anti-adhesion properties. The formulation consists of: 15 parts of fine bamboo powder (of which 30% is 1000 mesh bamboo powder and 70% is 250 mesh bamboo powder, forming a bimodal particle size distribution), 15 parts of 3000 mesh calcium carbonate, 60 parts of polybutylene adipate / terephthalate (PBAT), 5 parts of PLA; and 3 parts of coupling agent KH560, 1 part of compatibilizer Xibond250, 0.5 parts of antioxidant 1010, and 0.5 parts of lubricant EBS.

[0034] Preparation process: Twin-screw extrusion granulation is employed. During processing, the high flexibility of PBAT is utilized to encapsulate ultrafine powder. Specifically, 250-mesh large bamboo powder particles provide physical support during film formation, preventing bubble adhesion; 1000-mesh small particles fill the gaps. The resulting film possesses a unique plant fiber texture and matte finish, suitable for blow molding production of fully biodegradable shopping bags, garbage bags, and agricultural mulch films.

[0035] Example 3 This embodiment prepares a high-toughness film special material with the following composition: 20 parts of 500-mesh fine bamboo powder, 10 parts of 1500-mesh calcium carbonate, 60 parts of PBAT, 5 parts of PLA; 3 parts of coupling agent KH560, 1 part of compatibilizer Xibond 250, 0.5 parts of antioxidant 10100, and 0.5 parts of lubricant EBS.

[0036] Preparation process: Twin-screw extrusion granulation is used, with the process temperature controlled between 140℃ and 160℃. This formula balances the tensile strength and tear strength of the film by appropriately increasing the mesh size of the bamboo powder to 500 mesh, making it suitable for the production of agricultural mulch films.

[0037] Example 4 This embodiment uses a continuous mixing process to prepare a high-filler film masterbatch. The formula consists of: 35 parts of 1000-mesh fine bamboo powder, 15 parts of 3000-mesh talc powder, 45 parts of PBAT; 3 parts of coupling agent KH560, 1 part of compatibilizer AX8900, 0.5 parts of antioxidant 10100, and 0.5 parts of lubricant EBS.

[0038] Preparation process: A continuous internal mixer is used for mixing and granulation. The strong shearing action of the mixer ensures homogeneous dispersion of high-content ultrafine powder within the PBAT matrix. The resulting masterbatch is suitable for blending with pure PBAT resin to form blown films, exhibiting good dispersibility and light-blocking properties.

[0039] Example 5 This embodiment prepares a composite material suitable for extruded sheets. The formulation consists of: 40 parts of 800-mesh fine bamboo powder, 10 parts of 3000-mesh talc powder, 40 parts of PBAT, 5 parts of PLA; and 3 parts of coupling agent KH570, 1 part of compatibilizer Xibond 250, 0.5 parts of antioxidant 1076, and 0.5 parts of lubricant PETS.

[0040] Preparation process: Granulation is performed using a continuous internal mixer, and PETS is used to improve the processing flowability of the high-filler system. This material has a balance of rigidity and toughness, making it suitable for the extrusion production of blister packaging sheets.

[0041] Example 6 This embodiment prepares a highly filled bamboo powder masterbatch with a core-skin structure (corresponding to the content of Example 3). The formula consists of: 60 parts of 500-mesh fine bamboo powder, 15 parts of 1250-mesh talc powder, 20 parts of PLA; and 3 parts of coupling agent KH570, 1 part of compatibilizer Xibond250, 0.3 parts of chain extender ADR 4468, 0.6 parts of antioxidant 1076, and 0.2 parts of antioxidant 168.

[0042] Preparation process: A continuous internal mixing process is employed in a two-step method. The key step lies in the order of material addition: First, PLA resin, coupling agent, and lubricant are added to an internal mixer and melted at 140℃-160℃ to form a liquid carrier; then, 500-mesh bamboo powder and talc powder are added. The molten additives preferentially coat the surface of the bamboo powder to form a hydrophobic layer, which is then encapsulated by PLA resin, forming a "bamboo powder core - additive layer - resin skin" structure. This masterbatch has a bamboo powder content of up to 60%, is cut into regular pellets, and is dust-free. It can be used as a general-purpose filler masterbatch and added to pure resin for dilution as needed.

[0043] Example 7 This embodiment prepares a low-cost injection molding material with the following formulation: 20 parts of 250-mesh fine bamboo powder, 20 parts of 1500-mesh talc powder, 20 parts of 3000-mesh calcium carbonate, 25 parts of PBAT, 10 parts of PLA; and 3 parts of coupling agent KH570, 1 part of compatibilizer AX8900, 0.5 parts of antioxidant 1076, and 0.5 parts of lubricant EBS.

[0044] Preparation process: Granulation is carried out using a continuous internal mixer. By compounding various low-cost mineral fillers with coarser bamboo powder, material costs are significantly reduced while maintaining good injection molding performance.

[0045] Example 8 This embodiment prepares a high-filler film material using a twin-screw extrusion process. The formulation consists of: 10 parts of 500-mesh fine bamboo powder, 10 parts of 3000-mesh talc powder, 10 parts of 3000-mesh calcium carbonate, 50 parts of PBAT, 15 parts of PLA; and 1 part of coupling agent KH560, 1 part of compatibilizer AX8900, 1 part of compatibilizer Xibond 250, 0.3 parts of chain extender ADR 4468, 0.5 parts of antioxidant 1010, 0.5 parts of lubricant EBS, and 0.2 parts of dispersant PEG 4000.

[0046] Preparation process: Twin-screw extrusion granulation is used, with reactive extrusion incorporating chain extender ADR 4468. Suitable for packaging films requiring a certain level of strength.

[0047] Example 9 This embodiment utilizes whiskers to construct a micro-skeleton to prepare a high-rigidity extruded sheet (corresponding to the content of the aforementioned Example 4). The formula consists of: 12 parts of 1000-mesh fine bamboo powder, 35 parts of calcium sulfate whiskers, 50 parts of PLA; and 1 part of compatibilizer AX8900, 1 part of Xibond250, 0.5 parts of antioxidant 1010, and 0.5 parts of lubricant EBS.

[0048] Preparation process: Calcium sulfate whiskers with an average length of 50 μm are selected, ensuring a dimensional relationship of L ≥ 2 × D50 with 1000 mesh bamboo powder (D50 approximately 13 μm). Granulation is performed using a twin-screw extruder, with a reactive compatibilizer introduced during extrusion to enhance the interfacial bonding between the whiskers and the matrix. The calcium sulfate whiskers overlap within the matrix to form a rigid framework, with the bamboo powder filling the voids. The resulting sheet has a high modulus and an increased heat distortion temperature, making it suitable for applications requiring high rigidity, such as blister trays and electronic product packaging boxes.

[0049] Example 10 This embodiment prepares a high-strength injection-molding grade elastomer material with the following composition: 20 parts of 800-mesh fine bamboo powder, 25 parts of calcium sulfate whiskers, 40 parts of PBAT, 10 parts of PLA; and 2.5 parts of coupling agent KH570, 1 part of compatibilizer Xibond 250, 0.3 parts of chain extender ADR 4468, 0.5 parts of antioxidant 1076, 0.2 parts of antioxidant 168, and 0.5 parts of lubricant EBS.

[0050] Preparation process: Granulation is performed using a continuous internal mixer. Whiskers are used to reinforce the PBAT matrix, enabling the material to maintain flexibility while possessing sufficient structural strength.

[0051] Example 11 This embodiment verifies the synergistic effect of multiple additive systems in a high-filling system (corresponding to the content of the aforementioned Example 5). The formulation consists of: 50 parts of 1000-mesh fine bamboo powder, 15 parts of calcium sulfate whiskers, 10 parts of PBS, 20 parts of PBAT; and 3 parts of coupling agent KH570, 1 part of compatibilizer AX8900, 0.5 parts of antioxidant 1010, and 0.5 parts of lubricant PETS.

[0052] Preparation process: A continuous internal mixer is used for mixing and granulation. The high lubricity of PETS reduces the melt viscosity of the highly filled system, and the strong shearing action of the continuous internal mixer achieves high-concentration powder dispersion. While maintaining its fully biodegradable properties, this material exhibits extremely high hardness and dimensional stability, making it suitable for compression molding processes to manufacture thick-walled products such as boards and flower pots.

[0053] Example 12 This embodiment expands the selection of resin matrix to prepare PPC (polypropylene carbonate) based composite material (corresponding to the content of the aforementioned Example 6). The formulation consists of: 50 parts of 250-mesh fine bamboo powder, 40 parts of PPC, 5 parts of PBAT; and 4 parts of coupling agent KH560, 0.5 parts of antioxidant 1010, and 0.5 parts of lubricant PETS.

[0054] Preparation process: Granulation is performed using a continuous internal mixer. Due to the poor thermal stability of PPC, the processing temperature is strictly controlled between 120℃ and 140℃. Utilizing the high barrier properties of PPC and the toughening effect of PBAT, combined with the skeletal support of 250-mesh bamboo powder, the resulting material possesses both the feel of an elastomer and excellent barrier properties, making it suitable for special packaging films or elastic components.

[0055] Example 13 This embodiment prepares a PBST (polybutylene succinate / terephthalate) based composite material with the following composition: 15 parts of 800-mesh fine bamboo powder, 15 parts of calcium sulfate whiskers, 15 parts of calcium carbonate, 50 parts of PBST; and 3 parts of coupling agent KH560, 0.3 parts of chain extender ADR 4468, 0.5 parts of antioxidant 1076, 0.5 parts of lubricant PETS, and 0.2 parts of dispersant PEG60000.

[0056] Preparation process: Twin-screw extrusion granulation is used. Suitable for fully biodegradable mulch films, exhibiting excellent weather resistance and mechanical properties.

[0057] Example 14 This embodiment prepares a special material for thermoforming sheets. The formula consists of: 25 parts of 800-mesh fine bamboo powder, 25 parts of talc powder, 40 parts of PLA, 5 parts of PBS; and 3 parts of coupling agent KH550, 1 part of compatibilizer Xibond 250, 0.5 parts of antioxidant 1010, and 0.5 parts of lubricant EBS.

[0058] Preparation process: Granulation is carried out using a continuous internal mixer. The high content of talc powder and bamboo powder significantly improves the crystallization rate and heat distortion temperature of the material.

[0059] Example 15 This embodiment prepares a PPC-based high-filler masterbatch with the following composition: 40 parts of 600-mesh fine bamboo powder, 10 parts of talc powder, 10 parts of calcium sulfate whiskers, 38 parts of PPC; and 1 part of compatibilizer Xibond 250, 0.5 parts of antioxidant 1010, and 0.5 parts of lubricant EBS.

[0060] Preparation process: Granulation is performed using a continuous internal mixer, with strict temperature control to prevent PPC degradation. This solves the problem of difficult PPC resin filling and allows it to be used as a masterbatch additive in subsequent blown film or cast film production.

[0061] Example 16 This embodiment prepares a high-filler masterbatch suitable for compression molding. The formula consists of: 50 parts of 600-mesh fine bamboo powder, 10 parts of calcium sulfate whiskers, 35 parts of PBAT; and 2 parts of compatibilizer Xibond 250, 2 parts of compatibilizer AX8900, 0.5 parts of antioxidant 1010, and 0.5 parts of lubricant EBS.

[0062] Preparation process: Granulation is carried out using a continuous internal mixer. The extremely high filler content, combined with a dual compatibilizer system, ensures the dispersion stability of the masterbatch in subsequent processing.

[0063] Example 17 This embodiment prepares a general-purpose injection molding grade composite material with the following formulation: 10 parts of 1000-mesh fine bamboo powder, 20 parts of calcium carbonate, 10 parts of talc, 35 parts of PLA, 10 parts of PBAT, 10 parts of PBS; and 3 parts of coupling agent KH570, 1 part of compatibilizer Xibond 250, 0.5 parts of compatibilizer AX8900, and 0.5 parts of antioxidant 1010.

[0064] Manufacturing process: Twin-screw extrusion granulation is used. The multi-component resin blend balances rigidity and toughness, making it suitable for injection molding of general industrial products.

[0065] Example 18 This embodiment, based on Example 6 (formerly No. 3), verifies the dilution application effect of the masterbatch in microbial synthesis of polyester. The formulation consists of: 50 parts of the high-filler masterbatch prepared in Example 6, 30 parts of PHA (polyhydroxyalkanoate), 10 parts of PHB (polyhydroxybutyrate), 8 parts of PBS; and 1 part of compatibilizer Xibond 250, 0.5 parts of lubricant EBS, and 0.5 parts of antioxidant 1010.

[0066] Preparation process: After the above components are mixed evenly, they are fed into a twin-screw extruder for secondary plasticizing extrusion (i.e., the "dilution molding" step). Because the bamboo powder in the masterbatch has been pre-coated and dispersed, it exhibits excellent compatibility in the PHA / PHB matrix, with no secondary agglomeration. The resulting material biodegrades rapidly and is suitable for injection-molded products with extremely high environmental protection requirements.

[0067] Example 19 This embodiment verifies the toughening application of masterbatch in complex resin systems. The formulation consists of: 50 parts of the masterbatch prepared in Example 11, mixed with 30 parts of PHA, 10 parts of PHB, 6 parts of PBAT, 1 part of compatibilizer AX8900, 2 parts of compatibilizer Xibond 250, 0.5 parts of antioxidant 1010, and 0.5 parts of lubricant EBS.

[0068] Manufacturing process: Twin-screw extrusion dilution. Suitable for high-strength injection molded parts.

[0069] Example 20 This embodiment verifies the diluted application of PPC-based masterbatch. The formulation consists of: 60 parts of the masterbatch prepared in Example 12, 35 parts of PLA, 3 parts of PBAT, 1 part of compatibilizer AX8900, 0.5 parts of antioxidant 1010, and 0.5 parts of lubricant PETS.

[0070] Preparation process: Twin-screw extrusion dilution. This improves the processing properties of PPC resin, making it suitable for injection molding.

[0071] Example 21 This embodiment verifies the injection molding application of ultra-high proportion masterbatch addition. The formulation consists of 80 parts of the masterbatch prepared in Example 11 and 20 parts of PLA.

[0072] Manufacturing process: Twin-screw extrusion dilution. This significantly reduces material costs and is suitable for low-cost injection molded products.

[0073] Example 22 This embodiment verifies the application of masterbatch in the casting film process. The formulation consists of 70 parts of the masterbatch prepared in Example 16 and 30 parts of PHA.

[0074] Preparation process: Twin-screw extrusion granulation followed by casting. Suitable for the production of fully biodegradable cast films.

[0075] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A fully biodegradable composite material with high bamboo fiber content, characterized in that, The composite material is prepared from the following components in parts by weight: The composition includes 15-80 parts of biodegradable resin matrix, 5-60 parts of fine bamboo powder, 0-30 parts of inorganic mineral filler, 0.5-5 parts of interface modifier, and 0.1-1 parts of processing aid; the fine bamboo powder has a particle size of 100-1000 mesh and is uniformly dispersed in the biodegradable resin matrix.

2. The high bamboo fiber content fully biodegradable composite material according to claim 1, characterized in that, The inorganic mineral filler includes calcium sulfate whiskers (4). The median particle size D50 of the fine bamboo powder and the average length L of the calcium sulfate whiskers satisfy the following relationship: L≥2×D50; The calcium sulfate whiskers form a microscopic support framework in the biodegradable resin matrix, and the fine bamboo powder fills the voids in the microscopic support framework.

3. The high bamboo fiber content fully biodegradable composite material according to claim 1, characterized in that, The fine bamboo powder has a multi-level particle size compound structure, including a first particle size component and a second particle size component; The first particle size component has a mesh size of 100-500 mesh and accounts for 60%-80% of the total weight of the fine bamboo powder; The second particle size component has a mesh size of 800-1200 mesh and accounts for 20%-40% of the total weight of the fine bamboo powder.

4. The high bamboo fiber content fully biodegradable composite material according to claim 1, characterized in that, The biodegradable resin matrix is ​​selected from one or more of the following: polylactic acid (PLA), polybutylene adipate / terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate-adipate (PBSA), polyhydroxyalkanoate (PHA), polypropylene carbonate (PPC), and polyhydroxybutyrate (PHB). The interface modifier is selected from one or a combination of titanate coupling agents, aluminate coupling agents, silane coupling agents, maleic anhydride graft polymers, and epoxy coupling agents.

5. The high bamboo fiber content fully biodegradable composite material according to claim 1, characterized in that, The microstructure of the composite material has a core-skin structure; the core-skin structure is characterized by: With the fine bamboo powder (1) as the core, the surface of the fine bamboo powder (1) is coated with an intermediate layer (2) formed by the processing aid, and the intermediate layer is coated with a skin layer (3) formed by part of the biodegradable resin matrix.

6. A method for preparing a high bamboo fiber content fully biodegradable composite material as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step S1, Pretreatment: The fine bamboo powder is subjected to high-speed shear mixing under heating conditions, and the liquid interface modifier is sprayed to reduce the moisture content of the fine bamboo powder to below 0.5% to obtain activated bamboo powder. Step S2: Preparation of high-filler masterbatch: The activated bamboo powder, the inorganic mineral filler, the processing aid and the biodegradable resin matrix of the first part are put into a mixing equipment for melt blending, and then extruded and granulated to obtain a high-filler masterbatch with a bamboo powder content of 40%-60%. Step S3, dilution molding: The high-filler masterbatch is mixed with the biodegradable resin matrix of the second part in a certain proportion, and then melt-plasticized and homogenized by an extruder to obtain the high bamboo fiber content fully biodegradable composite material.

7. The preparation method according to claim 6, characterized in that, In step S2, the feeding sequence of the internal mixing equipment is as follows: First, the processing aid and the biodegradable resin matrix of the first part are added. After they melt to form a liquid phase environment, the activated bamboo powder and the inorganic mineral filler are added. The molten processing aid is preferentially adsorbed onto the surface of the activated bamboo powder to form a coating layer.

8. The preparation method according to claim 6, characterized in that, In step S3, the extruder is a twin-screw extruder; The preparation method further includes a reactive extrusion process: a chain extender is added through a side feed port or an exhaust port at 1 / 3 to 1 / 2 of the length-to-diameter ratio L / D of the twin-screw extruder. The chain extender comprises a multifunctional epoxy chain extender, one end group of which reacts with the end group of the biodegradable resin matrix, and the other end group bonds with the active groups on the surface of the activated bamboo powder.

9. The preparation method according to claim 8, characterized in that, The heating temperature in step S1 is 100℃-115℃, and the high-speed shear mixing speed is 2000-3000 rpm; the mixing equipment in step S2 is a continuous mixer, and its processing temperature is controlled at 130℃-160℃.

10. The application of the high bamboo fiber content fully biodegradable composite material according to any one of claims 1 to 5 in the preparation of fully biodegradable films, injection molded parts, extruded sheets, thermoformed products, die-cast products, mulch films or elastomer products.

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