Degradable composite materials and their preparation methods, heating devices

Abstract

This application relates to the field of environmentally friendly materials technology, and in particular to a biodegradable composite material, its preparation method, and a heating device. The biodegradable composite material provided in this application comprises the following raw material components in parts by weight: 25-35 parts coconut shell powder; 25-40 parts polylactic acid; 25-40 parts biodegradable copolyester; 3-8 parts cellulose nanocrystals; and 7-9 parts grafting agent. The coconut shell powder is treated sequentially with lipase and cellulase, and the particle size of the coconut shell powder is 800-2000 mesh. Through the combined action of the above-mentioned components, this application not only ensures the biodegradable properties of the material but also increases the overall strength and mechanical properties of the biodegradable composite material. Such a biodegradable composite material can be used for the outer shell of a heating device, reducing environmental pollution and showing great application potential.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of environmental protection materials, and particularly relates to a degradable composite material, a preparation method thereof and a heating device. BACKGROUND

[0002] Plastic is one of the most widely used basic materials in human production and life, but traditional plastic is not easy to degrade and can cause serious environmental pollution problems. Finding a suitable substitute for traditional plastic is an effective way to solve the problem from the source. Degradable plastic refers to plastic that is gradually decomposed into harmless substances such as water and carbon dioxide under specific environmental conditions through the action of microorganisms, light, oxygen or moisture. It is a good environmental protection substitute for traditional plastic. At present, starch-based degradable plastic has been marketed and applied, but starch-based degradable plastic has poor water resistance. The hydrophilicity of starch causes the material to soften, the strength to decrease, and the service life to be shortened in a humid environment after absorbing water. Its strength is also poorer than that of traditional plastic, and the production of starch-based degradable plastic also consumes grain resources, so its application is limited.

[0003] The heating device containing the aerosol generating substrate can heat the built-in aerosol generating substrate to form an aerosol. Such a heating device has been popular in the world in recent years, and its market is still in a rapid expansion period. However, the plastic shell of the heating device is not easy to degrade, which can easily cause environmental pollution. SUMMARY

[0004] The purpose of the present application is to provide a degradable composite material, a preparation method thereof and a heating device, aiming to solve the technical problem of how to form a degradable composite material with good mechanical properties to be well applied in the shell of the heating device. To achieve the above application purpose, the technical solution adopted by the present application is as follows:

[0005] In the first aspect, the present application provides a degradable composite material, which comprises the following raw material components by weight: 25-35 parts of coconut shell powder; 25~40 parts of polylactic acid; 25~40 parts of degradable copolyester; 3~8 parts of cellulose nanocrystal; 7~9 parts of grafting agent; The raw material of the coconut shell powder is treated with lipase and cellulase in sequence, and the particle size of the coconut shell powder is 800 mesh~2000 mesh.

[0006] The biodegradable composite material provided in this application comprises a certain weight proportion of coconut shell powder, polylactic acid (PLA), biodegradable copolyester, cellulose nanocrystals, and a grafting agent. The coconut shell powder is treated sequentially with lipase and then with cellulase. Lipase treatment removes the hydrophobic lipid barrier on the fiber surface of the coconut shell raw material, opening up the pore channels of the fibers. Cellulase treatment then allows for thorough penetration into the fiber interior for better sugar removal, effectively reducing the internal sugar residue. This reduces the surface polarity of the coconut shell powder, resulting in good compatibility with PLA, thus improving the material's mechanical properties. Cellulose nanocrystals enhance the material's rigidity and biodegradability. The biodegradable copolyester exhibits excellent flexibility and ductility, reducing the crystallinity of PLA and improving its brittleness. The grafting agent further improves the compatibility between coconut shell powder, cellulose nanocrystals, and PLA. Therefore, through the combined action of the above-mentioned components, this application not only ensures the biodegradable nature of the material but also increases the overall strength and mechanical properties of the biodegradable composite material. Such a biodegradable composite material can be used for the outer shell of heating devices, reducing environmental pollution and showing great application potential.

[0007] In some possible implementations, the aspect ratio of the cellulose nanocrystals is (1~100):1, and the modulus ranges from 135 GPa to 150 GPa. And / or, the total weight ratio of the coconut shell powder and the cellulose nanocrystals to the weight ratio of the grafting agent is (3~10):1; The weight ratio of polylactic acid to the biodegradable copolyester is (0.9~1.1):1.

[0008] In some possible implementations, the lipase includes a bacterial lipase, the bacteria including at least one of Bacillus subtilis, Bacillus licheniformis, and Bacillus thermophilus. And / or, the cellulase comprises a complex cellulase derived from fungi, wherein the fungi include at least one of Trichoderma reesei, Trichoderma viride, Trichoderma koningii, and Aspergillus niger.

[0009] In some possible implementations, the lipase treatment is carried out in a first solution containing lipase and having a pH of 7.0 to 9.0; And / or, the cellulase treatment is carried out in a second solution containing cellulase and having a pH of 4.0 to 6.0.

[0010] In some possible implementations, the biodegradable copolyester includes at least one of polybutylene terephthalate, polybutylene succinate, polycaprolactone, and poly(3-hydroxybutyrate-3-hydroxyhexanoate). And / or, the grafting agent includes at least one of acrylonitrile, methyl methacrylate, maleic anhydride, phthalic anhydride, and silane coupling agent.

[0011] Secondly, this application provides a method for preparing a biodegradable composite material, comprising: Provide the raw material components in the biodegradable composite material of this application in parts by weight; The coconut shell powder, polylactic acid, biodegradable copolyester, cellulose nanocrystals, and grafting agent are melt-blended to obtain a compound material. The mixed materials are processed and shaped to obtain the biodegradable composite material.

[0012] The method for preparing the biodegradable composite material provided in this application involves melt-blending and molding the aforementioned coconut shell powder, polylactic acid, biodegradable copolyester, cellulose nanocrystals, and grafting agent to obtain the biodegradable composite material. This preparation method is not only simple and easily scalable, but also ensures thorough mixing of the components during the melt-blending process. The resulting biodegradable composite material, through the combined action of its components, not only guarantees its biodegradability but also increases its overall strength and mechanical properties. The biodegradable composite material prepared in this way can be used for the outer shell of heating devices, reducing environmental pollution and demonstrating excellent application prospects.

[0013] In some possible implementations, the preparation steps of the coconut shell powder include: After the coconut shell raw material is cut into coconut shell fragments and washed with water, it is first soaked in a first solution containing lipase and with a pH value of 7.0~9.0 for a first soaking treatment, then soaked in a second solution containing cellulase and with a pH value of 4.0~6.0 for a second soaking treatment, and finally dried and crushed to obtain the coconut shell powder.

[0014] In some possible implementations, the size of the coconut shell fragments is 5cm to 7cm; And / or, the temperature of the water washing is 25℃~40℃; And / or, the mass fraction of the lipase in the first solution is 0.6%~0.8%; And / or, the temperature of the first soaking treatment is 10℃~45℃, and the time is 2h~5h; And / or, the mass fraction of the cellulase in the second solution is 0.1% to 0.7%; And / or, the temperature of the second soaking treatment is 10℃~50℃, and the time is 2h~5h; And / or, the drying process is carried out at a temperature of 80℃~105℃ for a time of 24h~48h.

[0015] In some possible implementations, the melt mixing temperature is 120°C to 170°C, and the time is 14h to 20h; And / or, the processing and molding includes: first crushing the mixed material into particles with a size range of 2.0mm to 3.0mm, and then placing the particles in a mold for molding.

[0016] Thirdly, this application provides a heating device, including a housing, the material of which includes the biodegradable composite material of the first aspect of this application or the biodegradable composite material prepared by the preparation method of the second aspect of this application.

[0017] The outer shell of the heating device provided in this application uses a biodegradable composite material unique to this application. Based on the fact that the biodegradable composite material not only has the characteristics of being biodegradable, but also has good strength and mechanical properties, the heating device of this application has a long service life and less environmental pollution.

[0018] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the preparation method of the biodegradable composite material provided in this application. Detailed Implementation

[0021] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0023] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0024] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0025] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0026] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a well-known unit of mass in the chemical industry, such as µg, mg, g, or kg.

[0027] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0028] The term "aerosol" broadly refers to all colloids that can be suspended in the air. The particle size of aerosols is generally about 10 nm to 10 μm, but can be, for example, 10 nm to 1000 nm. This application mainly refers to suspended microparticles / mixtures of suspended particles generated when a heating device is in operation, formed by heating an aerosol generating matrix, and the "mist" inhaled by the user is this type of aerosol.

[0029] The term "aerosol generating matrix" refers to a raw material that can generate aerosols upon heating. It is a basic component used in heating devices, whether in liquid, solid, or paste form. Aerosol generating matrix components can consist of various flavoring agents and flavoring substances. Heating and vaporizing the aerosol generating matrix can form aerosols for users to inhale.

[0030] The term "heating device" refers to a device that can heat the object to be heated, i.e., the aerosol-generating matrix, to form an aerosol, such as a liquid heating device or an electronic heating device. Heating devices typically use built-in heating elements (such as heating cores) to precisely heat a specially formulated aerosol-generating matrix to a specific temperature, causing some substances in the matrix to evaporate and generate an aerosol for user use.

[0031] The term "mesh count" refers to the number of openings on a sieve per square inch. It also indicates the particle size that can pass through the sieve; the higher the mesh count, the smaller the particle size. For example, 20 mesh means there are 20 holes per square inch of screen, and the corresponding screen size can be 0.850 mm; 30 mesh means there are 30 holes per square inch of screen, and the corresponding screen size can be 0.600 mm; 40 mesh means there are 50 holes per square inch of screen, and the corresponding screen size can be 0.425 mm; 100 mesh means there are 100 holes per square inch of screen, and the corresponding screen size can be 0.150 mm; 400 mesh means there are 400 holes per square inch of screen, and the corresponding screen size can be 0.038 mm; 800 mesh means there are 800 holes per square inch of screen, and the corresponding screen size can be 0.018 mm; 1000 mesh means there are 1000 holes per square inch of screen, and the corresponding screen size can be 0.013 mm, and so on.

[0032] Currently, the plastic shells used in heating devices containing aerosol-generating matrices are not easily degraded, which can easily lead to environmental pollution. Therefore, the application of biodegradable materials has important environmental significance and broad market prospects.

[0033] Coconut shells are the outer husks of coconuts, rich in coconut fiber, and are a byproduct of coconut processing. Coconuts are a widely cultivated economic crop in tropical regions worldwide, with an annual production exceeding 120 million tons. The utilization rate of their shell fiber is high, and the raw material supply is stable and sustainable. Coconut shells are rich in coconut fiber, which has a tensile strength of ≥50N, excellent wear resistance and compressive strength, and is biodegradable under natural conditions. Therefore, it is widely used in home furnishings, construction, agriculture, and other fields, making it a sustainable material that combines natural properties with industrial practicality.

[0034] Based on this, this application discloses a biodegradable composite material containing coconut shell components and its preparation process, which can be used as the outer shell of a heating device. The specific technical solution is as follows.

[0035] In a first aspect, embodiments of this application provide a biodegradable composite material. Specifically, the biodegradable composite material comprises the following raw material components in parts by weight: 25-35 parts coconut shell powder; 25-40 parts polylactic acid; 25-40 parts biodegradable copolyester; 3-8 parts cellulose nanocrystals; and 7-9 parts grafting agent; wherein the coconut shell powder raw material is sequentially treated with lipase and cellulase, and the particle size of the coconut shell powder is 800 mesh to 2000 mesh.

[0036] In the biodegradable composite material provided in this application embodiment, the coconut shell powder raw material is sequentially treated with lipase and cellulase. Lipase treatment removes the hydrophobic lipid barrier on the fiber surface of the coconut shell raw material, opening up the pore channels of the fibers. Cellulase treatment then allows it to fully penetrate the fiber interior for better sugar removal, effectively reducing the internal sugar residue. This reduces the surface polarity of the coconut shell powder, resulting in good compatibility with polylactic acid (PLA), thus improving the material's mechanical properties. Cellulose nanocrystals enhance the material's rigidity and biodegradability. The biodegradable copolyester exhibits excellent flexibility and ductility, reducing the crystallinity of PLA and improving its brittleness. Grafting agents further improve the compatibility between coconut shell powder, cellulose nanocrystals, and PLA. The combined effect of these components not only ensures the biodegradable nature of the material but also increases the overall strength and mechanical properties of the biodegradable composite material.

[0037] In some possible implementations, the raw material for coconut shell powder refers to coconut shell raw materials. Lipase, also known as glycerol ester hydrolase, belongs to the class of carboxyl ester hydrolases and can hydrolyze triglycerides into glycerol and fatty acids. Cellulase is a general term for a group of enzymes that degrade cellulose to produce glucose. It can specifically hydrolyze the glycosidic bonds between cellulose chains in coconut shell, breaking down polysaccharides into soluble monosaccharides (such as glucose), thereby reducing the polarity of coconut shell powder. In this application embodiment, the coconut shell powder selected is obtained by first treating with lipase and then with cellulase in order to better remove lipids and sugars from the coconut shell. Because lipids form a dense hydrophobic barrier on the surface of coconut shell fibers, lipase treatment can remove lipids, thereby opening up the pore channels of the fibers. Then, cellulase treatment removes sugars, allowing cellulase to fully penetrate into the fiber interior for a more thorough reaction, thus effectively reducing internal sugar residue.

[0038] In some possible implementations, the particle size of coconut shell powder is 800-2000 mesh. Specifically, mature coconut shells (thickness ≥2mm) are cut into coconut shell fragments, then rinsed with clean water to remove coconut meat residue and sand; the coconut shell fragments are then treated with lipase, then with cellulase, and finally cleaned, dried, and crushed into coconut shell powder of 800-2000 mesh.

[0039] In some possible implementations, the lipase includes bacterial lipases, which can be common lipase-producing strains, including at least one of Bacillus subtilis, Bacillus licheniformis, and Bacillus thermophilus. Compared to fungal lipases, bacterial lipases have better alkali resistance and thermal stability, and can efficiently hydrolyze the dense waxy layer on the surface of coconut fiber.

[0040] In some possible implementations, the optimal pH value of the bacterial lipases mentioned above is 7.0 to 9.0. Therefore, lipase treatment is carried out in a first solution containing lipase and with a pH value of 7.0 to 9.0; that is, lipase treatment under neutral or weakly alkaline conditions can better exert lipase activity.

[0041] In some possible implementations, the cellulase includes a fungal-derived complex cellulase, which can be a commonly used cellulase-producing strain, including at least one of *Trichoderma reesei*, *Trichoderma viride*, *Trichoderma konjac*, and *Aspergillus niger*. Fungal-derived complex cellulases can better remove sugars from coconut shells.

[0042] In some possible implementations, the optimal pH value of the aforementioned fungal-derived complex cellulase is 4.0 to 6.0. Therefore, cellulase treatment is carried out in a second solution containing cellulase with a pH value of 4.0 to 6.0; that is, cellulase treatment under acidic conditions can better exert cellulase activity.

[0043] Among some possible implementations, polylactic acid (PLA) is a biodegradable polymer. For example, PLA can be a biodegradable polymer made from lactic acid produced by fermentation of plants such as corn and sugarcane. Its unique rigid molecular chain structure endows the product with excellent mechanical properties, which not only conforms to the environmental protection concept of sustainable development, but also its unique ester bond structure can achieve biodegradation at the end of the material's service life, with degradation products being only carbon dioxide and water, resulting in zero pollution to the environment.

[0044] In some possible implementations, biodegradable copolyesters are aliphatic / aliphatic-aromatic polyester polymers prepared through copolymerization modification. Based on biodegradable polyesters, two or more different monomers (or copolymer units) are combined in the same molecular chain through a polycondensation reaction, combining the performance advantages of each raw material monomer while achieving environmental degradability. For example, biodegradable copolyesters include at least one of polybutylene terephthalate (PET), polybutylene succinate (PBS), polycaprolactone (PVC), and poly(3-hydroxybutyrate-3-hydroxyhexanoate).

[0045] Polybutylene terephthalate (PBAT) is an aliphatic-aromatic copolyester copolymerized from adipic acid (AA), terephthalic acid (PTA), and butanediol (BDO). It is a flexible and durable biodegradable copolyester with excellent ductility. When blended with polylactic acid (PLA), it reduces PLA's crystallinity, improving its brittleness and melt flowability. Polybutylene succinate (PBS) is a fully aliphatic polyester with similar molecular chain flexibility to PBAT. It has a similar elongation at break to PBAT but better heat resistance and can degrade under composting conditions. Polycaprolactone (PCL) is an aliphatic biodegradable polyester prepared by ring-opening polymerization of ε-caprolactone. It has moderate tensile strength, ultra-flexible and highly elastic properties, even surpassing PBAT in flexibility. It possesses good impact and bending resistance and can degrade under composting conditions. Poly(3-hydroxybutyrate-3-hydroxyhexanoate) (PHBH) is a copolymer of two monomers, 3-hydroxybutyrate (3HB) and 3-hydroxyhexanoate (3HH), through microbial fermentation. It has good thermal stability, mechanical properties, degradation performance and biocompatibility.

[0046] In some possible implementations, cellulose nanocrystals (CNCs) are also known as nanocellulose whiskers. For example, CNCs can be highly crystalline nanoscale rod-shaped crystals extracted from natural cellulose (such as plant cell walls and bacterial cellulose). In the embodiments of this application, the coconut shell powder used is micron-sized coconut shell powder, and the CNCs are nanoscale fibers. The two form a "micron-nano composite network." The CNCs can fill the gaps between the coconut shell powder, reduce the agglomeration of single fibers, and thus reduce the risk of material quality fluctuations caused by uneven fiber distribution.

[0047] In some possible implementations, the aspect ratio of cellulose nanocrystals is (1~100):1, and the modulus ranges from 135 GPa to 150 GPa. These high aspect ratio and high modulus cellulose nanocrystals can form a "rigid network" in composite materials, sharing the load through interfacial stress transfer and improving the material's mechanical properties. Furthermore, the hydroxyl groups on the surface of the cellulose nanocrystals can serve as "nucleation sites" for polylactic acid (PLA) molecular chains, promoting PLA crystallization (e.g., increasing crystallinity from 25% to 35%). Simultaneously, the biodegradability of the cellulose nanocrystals themselves (weight loss >80% after 180 days under composting conditions) can synergistically accelerate overall degradation with PLA and biodegradable copolyesters.

[0048] In some possible implementations, grafting agents can improve the compatibility between components, form chemical bonds with other components, enhance interfacial bonding, and thus improve the toughness of the material. For example, grafting agents include at least one of acrylonitrile, methyl methacrylate, maleic anhydride, phthalic anhydride, and silane coupling agents. The silane coupling agent can be at least one of KH550, KH560, KH590, KH602, etc.

[0049] For example, in the biodegradable composite material of this application, the coconut shell powder obtained by the first treatment with lipase and cellulase can be any one or any two of the following weight values: 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, etc. The polylactic acid can be any one or any two of the following weight values: 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, etc. The biodegradable copolyester can be any one or any two of the following weight values: 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, etc. The cellulose nanocrystals can be any one or any two of the following weight values: 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, etc. The grafting agent can be any one or any two of the following weight values: 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, etc.

[0050] In some possible implementations, the weight ratio of polylactic acid (PLA) to biodegradable copolyester is (0.9~1.1):1. Blending the biodegradable copolyester with PLA in this ratio can better reduce the crystallinity of PLA, improve its brittleness, and enhance melt flowability. In some possible implementations, the weight ratio of the total weight of coconut shell powder and cellulose nanocrystals to the grafting agent is (3~10):1; mixing coconut shell powder, cellulose nanocrystals, and grafting agent in this ratio can better improve the compatibility between components and enhance interfacial bonding.

[0051] In summary, in this embodiment, the coconut shell powder treated sequentially with lipase and cellulase reduces its surface polarity, improves the compatibility between the coconut shell powder and polylactic acid, and thus enhances the material's mechanical properties. Furthermore, the enzymatic degreasing and desugaring process avoids the use of alkali and acid degreasing processes, reducing operational risks and environmental pollution, and minimizing fiber damage, which is beneficial for improving the material's strength. The addition of cellulose nanocrystals enhances the material's rigidity and biodegradability. The addition of a grafting agent further improves the compatibility between coconut shell powder, cellulose nanocrystals, and polylactic acid, thereby improving the material's performance, increasing its strength, and ensuring its biodegradability. This biodegradable composite material can be used in the outer shell of heating devices, thereby reducing the environmental pollution caused by heating devices. In addition, compared to starch-based biodegradable plastics, the biodegradable composite material with coconut shell as a component also reduces the consumption of food resources.

[0052] Secondly, embodiments of this application provide a method for preparing a biodegradable composite material. For example... Figure 1 As shown, the preparation method of this application embodiment includes the following steps: S01: Provide the components in each weight part of the biodegradable composite material of the embodiments of this application.

[0053] S02: Coconut shell powder, polylactic acid, biodegradable copolyester, cellulose nanocrystals and grafting agent are melt-blended to obtain a blended material.

[0054] S03: The mixed materials are processed into shapes to obtain biodegradable composite materials.

[0055] The method for preparing the biodegradable composite material in this application is not only simple and easy to scale up, but also ensures that the components are fully mixed during the melt mixing process. The resulting biodegradable composite material, through the combined action of the components, not only ensures the biodegradable properties of the material, but also increases the overall strength and mechanical properties of the biodegradable composite material. The biodegradable composite material prepared in this way can be used for the shell of heating devices, reducing environmental pollution and showing great application prospects.

[0056] In step S01, the components provided by weight include: 25-35 parts coconut shell powder; 25-40 parts polylactic acid; 25-40 parts biodegradable copolyester; 3-8 parts cellulose nanocrystals; and 7-9 parts grafting agent. The coconut shell powder raw material is sequentially treated with lipase and cellulase. For details on the selection and function of specific components, please refer to the above.

[0057] In some possible implementations, the preparation steps of coconut shell powder include: cutting coconut shell raw material into coconut shell fragments and washing them with water; first soaking them in a first solution containing lipase and with a pH of 7.0~9.0; then soaking them in a second solution containing cellulase and with a pH of 4.0~6.0; and finally drying them and pulverizing them to obtain coconut shell powder.

[0058] Lipases can be bacterial lipases, with commonly used production strains including at least one of Bacillus subtilis, Bacillus licheniformis, and Bacillus stearothermophilus. Compared to fungal lipases, bacterial lipases exhibit better alkali resistance and thermal stability, enabling them to efficiently hydrolyze the dense, stubborn waxy layer on the surface of coconut fiber. The optimal pH for bacterial lipases is 7.0-9.0 (neutral or weakly alkaline), therefore a solution with a pH of 7.0-9.0 is used for the first soaking treatment. Cellulases can be considered fungal-derived complex cellulases, with commonly used production strains including at least one of Trichoderma reesei, Trichoderma viride, Trichoderma koningii, and Aspergillus niger. The optimal pH for fungal-derived complex cellulases is 4.0-6.0 (acidic), therefore a solution with a pH of 4.0-6.0 is used for the second soaking treatment.

[0059] To effectively remove lipids and sugars from coconut shells, which form a dense hydrophobic barrier on the fiber surface due to lipids, the first soaking treatment (described above) removes lipids and opens up the fiber's pores. The second soaking treatment then allows the cellulase desaccharification reagent to fully penetrate the fiber and react completely, resulting in more thorough sugar removal and effectively reducing internal sugar residue. If a desaccharification-then-degreasing process is used, the dense hydrophobic barrier formed by the lipids in the coconut shell makes it difficult for the second solution containing cellulase to fully penetrate the fiber, leading to incomplete sugar removal and more sugar residue inside the fiber, thus affecting the performance of the final biodegradable composite material.

[0060] In some possible implementations, the coconut shell raw material is cut into pieces of 5cm to 7cm in size, for example, 6cm. Cutting the coconut shell into pieces helps to increase the surface area of ​​the coconut shell, thereby increasing the contact area between the coconut shell and the solution in the subsequent defatting and desugaring steps and improving the processing effect. Washing with clean water to remove impurities such as coconut meat and sand can further improve the quality of the raw material. For example, the washing temperature is 25℃ to 40℃.

[0061] In some possible implementations, the first soaking treatment is a degreasing process. In this application embodiment, lipase is used to enzymatically hydrolyze the lipids in the coconut shell. The reaction conditions are mild, replacing the traditional degreasing process using NaOH solution, reducing environmental pollution, improving production safety, and minimizing damage to the coconut fiber in the coconut shell.

[0062] Lipase is used to decompose lipids in coconut shell fragments via enzymatic reaction. Lipid removal degrades the lipid barrier, facilitating the complete biodegradation of the material. Simultaneously, it roughens the fiber surface, increasing its surface area and improving the effectiveness of subsequent desugaring processes. Different lipase concentrations, soaking temperatures, and soaking times all affect the degreasing effect. Specifically, the mass fraction of lipase in the first solution is 0.6%~0.8% (e.g., 0.6%, 0.7%, 0.8%, etc.), and the solvent can be water. Excessive lipase usage increases costs, while insufficient usage results in ineffective degreasing. The above conditions aim to balance degreasing efficiency and cost. Specifically, the first soaking temperature is 10℃~45℃, and the time is 2h~5h (e.g., soaking at 40℃ for 4h in a first solution with a pH of 8.0). Excessively high temperatures can deactivate lipase, while excessively low temperatures reduce enzyme activity. Too short a soaking time results in insufficient degreasing, while too long a soaking time affects production efficiency. Therefore, the above conditions aim to balance enzyme activity, degreasing efficiency, and cost.

[0063] In some possible implementations, the second soaking treatment is a desugaring process. In this application, cellulase is used to specifically hydrolyze the glycosidic bonds between cellulose chains in coconut shells, breaking down polysaccharides into soluble monosaccharides (such as glucose), thereby reducing the polarity of the coconut shell powder. Using cellulase to enzymatically hydrolyze the sugars in coconut shells provides a mild reaction, replacing the traditional acid hydrolysis and heating desugaring process, reducing environmental pollution, improving production safety, and minimizing damage to the coconut fiber in the coconut shell.

[0064] Different cellulase concentrations, soaking temperatures, and soaking times all affect the desugaring effect. Specifically, the mass fraction of cellulase in the second solution is 0.1%~0.7% (e.g., 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, etc.), and the solvent can be water. Excessive cellulase usage increases costs, damages coconut fiber, and affects fiber strength; insufficient usage reduces degreasing effect. The goal is to balance desugaring effect, material performance, and cost under these conditions. Specifically, the second soaking temperature is 10℃~50℃, and the time is 2h~5h (e.g., soaking at 40℃ for 4h in a second solution with a pH of 5.0). Excessively high temperatures will inactivate lipase, while excessively low temperatures will reduce enzyme activity. Insufficient soaking time results in incomplete degreasing, while excessive soaking time affects production efficiency and damages coconut fiber, affecting fiber strength. Therefore, the goal is to balance enzyme activity, desugaring effect, material performance, and process cost under the above conditions.

[0065] In some possible implementations, after defatting and desugaring, the coconut shell fragments are hot-air dried, then pulverized into coconut shell powder using a pulverizer and sealed for later use. Drying the coconut shell fragments helps reduce the interference of moisture in subsequent melt-blending processes, improving product quality. Pulverizing the coconut shells into powder helps increase the surface area of ​​the coconut shells, increasing the contact area between the coconut shells and other components in the melt-blending process, further improving product quality. The drying temperature is 80℃~105℃ (e.g., 85℃), and the time is 24h~48h. The particle size of the pulverized coconut shell powder can be 800~2000 mesh. The moisture content of the coconut shell powder can be ≤6%.

[0066] In some possible implementations, the melt-blending temperature is 120°C to 170°C, and the time is 14 to 20 hours. Specifically, coconut shell powder, polylactic acid, biodegradable copolyester, cellulose nanocrystals, and grafting agents are placed in a high-speed mixer for melt-blending; for example, melt-blending at 150°C for 18 hours.

[0067] In the above compounding process: Coconut shells are rich in coconut fiber, a byproduct of coconut processing. Coconut fiber has a tensile strength ≥50N, excellent wear resistance and compressive strength, and is biodegradable under natural conditions. It is a sustainable material that combines natural properties with industrial practicality. Adding coconut shell powder can effectively improve the strength of the material. Coconut fiber has a higher thermal conductivity than polymers, which helps conduct heat in the blend during melt compounding, making the heat distribution more uniform, preventing local overheating, and improving product quality. Biodegradable copolyester has good ductility. Blending it with polylactic acid (PLA) reduces the crystallinity of PLA, improves its brittleness, and enhances melt flowability. Cellulose nanocrystals have a high aspect ratio and high modulus, which can form a "rigid network" in the composite material, sharing the load through interfacial stress transfer and improving the mechanical properties of the material. The hydroxyl groups on the surface of cellulose nanocrystals can serve as "nucleation sites" for PLA molecular chains, promoting PLA crystallization. At the same time, the biodegradability of PLA itself synergistically accelerates overall degradation. Micron-sized coconut shell powder and nano-sized cellulose nanocrystals form a "micron-nano composite network." The cellulose nanocrystals fill the gaps between the coconut shell powder, reducing the risk of single fiber agglomeration and minimizing material quality fluctuations caused by uneven fiber distribution. Grafting agents improve the compatibility between components, forming chemical bonds with other components and enhancing interfacial bonding, thereby improving the material's toughness. Therefore, coconut shell powder, polylactic acid, biodegradable copolyester, grafting agent, and cellulose nanocrystals work synergistically to not only ensure the biodegradability of the material but also enhance the mechanical properties (high tensile strength and toughness: polylactic acid provides high tensile strength, while biodegradable copolyester imparts flexibility and impact resistance, forming a complementary structure after blending; the coconut fiber and cellulose nanocrystals in coconut shell powder significantly improve the rigidity and creep resistance of the composite material, and the fiber network structure disperses stress and inhibits crack propagation) and processing performance (biodegradable copolyester has easy processing characteristics, and the grafting agent reduces interfacial tension, making the composite material easy to form through processes such as blown film and injection molding; the large polarity difference between polylactic acid and biodegradable copolyester is enhanced by the grafting agent forming chemical bonds at the interface, strengthening the bond between the two and reducing phase separation).

[0068] In some possible implementations, the processing and molding process includes: first, crushing the compounded material into particles with a size range of 2.0 mm to 3.0 mm, and then placing the particles in a mold for molding. Specifically, the compounded material obtained from melt mixing is crushed into elongated particles using a pulverizer, with a diameter of 2.0 to 3.0 mm and a length of 2.5 to 3.5 mm. The mold parameters (such as size, dimensions, and shape) can be set according to various production requirements and application scenarios; there are no fixed requirements.

[0069] In some possible implementations, the preparation method of biodegradable composite material includes: (1) cutting mature coconut shells (thickness ≥ 2 mm) into pieces, and then rinsing them with water to remove coconut meat residue and sand. (2) soaking the coconut shell pieces in a deionized aqueous solution of lipase (i.e., the first soaking treatment) to remove the lipids contained therein, and then washing them with deionized water for later use. (3) soaking the coconut shell pieces in a deionized aqueous solution of cellulase (i.e., the second soaking treatment) to remove the sugars contained therein, and then washing them with deionized water for later use. (4) drying the defatted and desugared coconut shell pieces with hot air, and then crushing them into coconut shell powder with a pulverizer, and sealing them for later use. (5) putting coconut shell powder, polylactic acid, biodegradable copolyester, cellulose nanocrystals and grafting agent into a high-speed mixer to mix them together to obtain a blend. After the blend cools down, it is melt-blended. (6) crushing the material obtained by melt-blending into granules with a diameter of 2.0~3.0 mm and a length of 2.5~3.5 mm. (6) The material particles are placed in a mold to be processed and shaped according to production needs, and a biodegradable composite material is obtained.

[0070] Thirdly, embodiments of this application provide a heating device. Specifically, the heating device of this application includes a housing, and the material of the housing includes the biodegradable composite material of the first aspect of this application or the biodegradable composite material prepared by the preparation method of the second aspect of this application.

[0071] The outer shell of the heating device uses a biodegradable composite material unique to the embodiments of this application. Based on the fact that the biodegradable composite material not only has the characteristics of being biodegradable, but also has good strength and mechanical properties, the heating device of this application has a long service life and less environmental pollution.

[0072] In some possible implementations, the heating device contains an aerosol generating matrix. Specifically, the heating device of this application embodiment includes a heating core and an aerosol generating matrix contained within the heating core. The heating core is encased in a shell, which uses a biodegradable composite material unique to this application embodiment.

[0073] The following description is based on specific embodiments.

[0074] Example 1 A method for preparing a composite material includes the following steps: Step (1): Mature coconut shells (thickness ≥ 2mm) are cut into pieces of about 6cm using a jaw crusher, and then rinsed with 40℃ water to remove any coconut meat residue and sand.

[0075] Step (2): The coconut shell fragments obtained in step (1) were transferred to a heated water tank and soaked in a 0.6% (w / w) deionized lipase aqueous solution with a pH of 8.0 at a temperature of 40°C for 4 hours. After soaking, the fragments were removed, rinsed with deionized water, and set aside for later use.

[0076] Step (3): The coconut shell fragments obtained in step (2) were transferred to a heated water tank and soaked in a 0.3% (w / w) deionized water solution containing cellulase. The solution pH was 5.0, the soaking temperature was 40℃, and the soaking time was 4 hours. After soaking, the fragments were removed, rinsed with deionized water, and set aside for later use.

[0077] Step (4): The coconut shell fragments obtained in step (3) are dried with hot air at 85°C for 48 hours and pre-treated by a pulverizing device to obtain coconut shell powder with a particle size of 1~5mm. The coconut shell powder with a particle size of 1~5mm is then coarsely pulverized by a high-efficiency pulverizer to obtain coconut shell powder with a mesh size of 20~40. The powder is then further processed by an ultrafine powder processing pulverizer to obtain coconut shell powder with a mesh size of 200~500. Finally, the powder is further processed by an ultrafine powder processing pulverizer or a bamboo powder air jet mill to obtain coconut shell powder with a mesh size of 800~2000, and then sealed and stored.

[0078] Step (5): According to the weight parts, take 30 parts of 800~2000 mesh coconut shell powder, 28 parts of polylactic acid, 28 parts of polybutylene terephthalate-adipate, 6 parts of cellulose nanocrystals, and 8 parts of maleic anhydride grafting agent obtained in step (4) and put them into a high-speed mixer to mix them together to obtain a blend. After the blend is cooled, it is melt-mixed at a temperature of 150°C for 18 hours.

[0079] Step (6): The material obtained from the melt mixing in step (5) is crushed into granules using a pulverizer. The granules have a diameter of 2.0~3.0 mm and a length of 2.5~3.5 mm.

[0080] Step (7): According to production needs, the granular material obtained in step (6) is placed in a mold and processed to form a biodegradable composite material containing coconut shell components.

[0081] Example 2 The difference between this embodiment and Embodiment 1 is that the lipase mass fraction in step (2) is 0.8%, the soaking temperature is 45℃, and the soaking time is 5h. Everything else is the same as in Embodiment 1.

[0082] Example 3 The difference between this embodiment and Embodiment 1 is that the cellulase mass fraction in step (3) is 0.1%, the soaking temperature is 45℃, and the soaking time is 5h. Everything else is the same as in Embodiment 1.

[0083] Example 4 The difference between this embodiment and Embodiment 1 is that the melting and mixing time in step (5) is 14 hours and the temperature is 120°C. Everything else is the same as in Embodiment 1.

[0084] Example 5 The difference between this embodiment and Example 1 is that in step (5), the proportions of each component are: 25 parts coconut shell powder, 30 parts polylactic acid, 30 parts polybutylene terephthalate-adipate, 8 parts cellulose nanocrystals, and 7 parts maleic anhydride grafting agent. All other components are the same as in Example 1.

[0085] Example 6 The difference between this embodiment and Example 1 is that in step (5), the proportions of each component are: 35 parts coconut shell powder, 25 parts polylactic acid, 25 parts polybutylene terephthalate-adipate, 3 parts cellulose nanocrystals, and 9 parts maleic anhydride grafting agent. Everything else is the same as in Example 1.

[0086] Example 7 The difference between this embodiment and Embodiment 1 is that in step (5), the proportions of each component are as follows: 28 parts coconut shell powder, 28 parts polylactic acid, 28 parts polybutylene terephthalate-adipate, 5 parts cellulose nanocrystals, and 8 parts maleic anhydride grafting agent. All other aspects are the same as in Embodiment 1.

[0087] This application also includes comparative examples. Compared with the embodiments, the processing of one or more steps in the comparative examples is different, or important operations are missing in one or more steps. The following are comparative examples: Comparative Example 1 The difference between this comparative example and Example 1 is that in step (2), sodium hydroxide aqueous solution is used for defatting. The specific operation is as follows: the coconut shell fragments obtained in step (1) are transferred to a heated water tank and soaked in a 5% sodium hydroxide aqueous solution at a temperature of 40°C for 2 hours. Then, they are taken out, rinsed with deionized water, and set aside for use. The other operation steps are exactly the same as in Example 1.

[0088] Comparative Example 2 The difference between this comparative example and Example 1 is that acid hydrolysis is used instead of desaccharification in step (3). The specific operation is as follows: the coconut shell fragments obtained in step (2) are transferred to a reactor, soaked in a 2% (w / w) dilute sulfuric acid deionized water solution for 20 min, heated to 100°C and refluxed for 1.5 h, then taken out and washed with deionized water for later use. Other operation steps are exactly the same as in Example 1.

[0089] Comparative Example 3 The difference between this comparative example and Example 1 is that in step (4), the coconut shell fragments were not crushed to a particle size of 800-2000 mesh, but rather to 20-40 mesh and then sealed for storage. The other operating steps are exactly the same as in Example 1.

[0090] Comparative Example 4 The difference between this comparative example and Example 1 is that maleic anhydride grafting agent is not added in step (5), while the other operation steps are exactly the same as in Example 1.

[0091] Comparative Example 5 The difference between this comparative example and Example 1 is that the order of steps (2) and (3) in Example 1 is reversed (i.e., cellulase treatment is performed first, followed by lipase treatment). All other operating steps are exactly the same as in Example 1.

[0092] Comparative Example 6 The difference between this comparative example and Example 1 is that steps (2) and (3) are combined and defatting and desugaring are performed simultaneously. The operation is as follows: the coconut shell fragments obtained in step (1) are transferred to a heated water tank and soaked in a mixed deionized water solution of lipase (0.6% by mass) and cellulase (0.3% by mass). The solution pH is 5.0, the soaking temperature is 40°C, and the soaking time is 4 hours. Then, the fragments are taken out, washed with deionized water, and set aside for later use. The other operation steps are exactly the same as in Example 1.

[0093] Mechanical property testing The mechanical properties of the biodegradable composite materials containing coconut shell components prepared in Examples 1-7 and Comparative Examples 1-6 were tested, and their tensile strength, flexural strength and impact strength were examined respectively.

[0094] The test was conducted in accordance with the requirements of the national standard GB / T 2918, using a standard environment: temperature 23℃±2℃, relative humidity 50%±5%; the sample conditioning time was not less than 40 hours to eliminate the influence of molding internal stress and environmental temperature and humidity on performance.

[0095] Tensile strength testing was performed according to GB / T 1040.1-1040.4. A uniform axial tensile load was applied to a standard dumbbell-shaped specimen on a universal testing machine until the specimen fractured. The maximum load during the test was recorded, and the tensile strength data were calculated. Ten specimens were tested repeatedly in each group.

[0096] Bending strength testing was conducted according to GB / T 9341 standard using a universal testing machine and the three-point bending method: the specimen was placed on two fixed supports, and a vertical concentrated load was applied to the midpoint of the specimen by an indenter, causing the specimen to bend until it fractured or reached the specified deflection. The bending strength data were calculated, and the measurement was repeated for each group of 10 specimens.

[0097] The impact strength test was conducted using a simply supported beam impact test, with GB / T 1043.1 as the standard. Ten samples were tested repeatedly in each group.

[0098] The test results are shown in Table 1 below: Table 1 Item Tensile strength (Mpa Flexural strength (Mpa ） Impact strength (kJ / m Example 1 ） <![CDATA[ Example 2 Example 3 2 ) ]]> Example 4 16.50 ± 0.80 23.80 ± 0.50 12.10 ± 0.40 Example 5 16.30 ± 0.30 23.60 ± 0.70 12.00 ± 0.30 Example 6 16.20 ± 0.70 23.50 ± 0.80 11.90 ± 0.50 Example 7 16.00 ± 0,80 23.20 ± 0.90 11.80 ± 0.40 Comparative Example 1 16.40 ± 0.60 23.70 ± 1.00 12.05 ± 0.60 Comparative Example 2 15.80 ± 0.70 22.90 ± 0.70 11.60 ± 0.40 Comparative Example 3 16.10 ± 0.40 23.30 ± 0.50 11.90 ± 0.30 Comparative Example 4 14.20 ± 0.50 20.50 ± 0.70 10.50 ± 0.30 Comparative Example 5 14.30 ± 0.70 20.60 ± 1.00 10.60 ± 0.30 Comparative Example 6 12.80 ± 0.80 18.00 ± 0.90 9.20 ± 0.60 ​ 13.50 ± 0.50 19.50 ± 0.80 10.00 ± 0.50 ​ 14.10 ± 0.70 20.30 ± 0.70 10.40 ± 0.40 ​ 13.90 ± 0.80 19.80 ± 1.00 10.10 ± 0.50 The test results show that the biodegradable composite materials containing coconut shell components prepared in Examples 1-7 all exhibit better mechanical properties compared to the comparative examples. Comparative Examples 1 and 2 used alkaline degreasing with sodium hydroxide solution and acid hydrolysis to remove sugar, respectively. These reaction conditions were relatively harsh, potentially damaging the coconut fiber in the coconut shell and ultimately affecting the material's strength. Furthermore, these chemical treatment methods increased the risks of operational safety and environmental pollution. The coconut shell powder in Comparative Example 3 had excessively large particle size and a smaller surface area compared to the examples, which hindered the interaction between the coconut shell powder and other components in the material, thus negatively impacting the material's mechanical properties. Comparative Example 4 lacked a grafting agent, which was detrimental to improving the compatibility of the components and also affected the improvement of the material's mechanical properties. Comparative Example 5 used a process sequence of first removing sugar and then degreasing, resulting in insufficient sugar removal and affecting the material's performance. Comparative Example 6 mixed lipase and cellulase for simultaneous degreasing and desaccharification. The solution pH was 5.0, which is the optimal pH for cellulase, but the lipase was inactivated, leading to failed degreasing and insufficient sugar removal, thus affecting the material's mechanical properties.

[0099] In summary, this application discloses a biodegradable composite material containing coconut shell components and its preparation process. This biodegradable composite material can be used as the outer shell of a heating device. By crushing the coconut shell and sequentially degreasing and desugaring it, the surface polarity of the coconut shell is reduced, improving the compatibility between coconut shell powder and polylactic acid, thereby enhancing the mechanical properties of the material. The sequential degreasing and desugaring using an enzymatic method avoids the use of alkaline and acidic degreasing processes, reducing operational risks and environmental pollution, and also reducing fiber damage, which is beneficial to improving the strength of the material. Simultaneously, the introduction of polylactic acid and biodegradable copolyester gives the material both high tensile strength and toughness. The coconut fiber and cellulose nanocrystals in the coconut shell powder form a "micron-nano composite network," with the cellulose nanocrystals filling the gaps in the coconut shell powder, reducing fiber agglomeration and thus reducing the risk of material quality fluctuations due to uneven fiber distribution. This significantly improves the rigidity and creep resistance of the composite material, and the fiber network structure disperses stress, thereby inhibiting crack propagation. The addition of grafting agents further improves the compatibility between coconut shell powder, cellulose nanocrystals, and polylactic acid, thereby enhancing the material's performance and strength while ensuring its complete biodegradability. Furthermore, biodegradable composite materials using coconut shells as a component reduce the consumption of food resources compared to starch-based biodegradable plastics.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A biodegradable composite material, characterized in that, The raw material components include the following parts by weight: 25-35 parts coconut shell powder; Polylactic acid 25-40 parts; 25-40 parts of biodegradable copolyester; 3-8 parts of cellulose nanocrystals; 7-9 parts grafting agent; The coconut shell powder is made from raw materials that are treated with lipase and cellulase in sequence, and the particle size of the coconut shell powder is 800 mesh to 2000 mesh.

2. The biodegradable composite material as described in claim 1, characterized in that, The aspect ratio of the cellulose nanocrystals is (1~100):1, and the modulus ranges from 135Gpa to 150Gpa. And / or, the total weight ratio of the coconut shell powder and the cellulose nanocrystals to the weight ratio of the grafting agent is (3~10):1; And / or, the weight ratio of the polylactic acid to the biodegradable copolyester is (0.9~1.1):

1.

3. The biodegradable composite material as described in claim 1, characterized in that, The lipase includes bacterial lipase, and the bacteria include at least one of Bacillus subtilis, Bacillus licheniformis, and Bacillus thermophilus. And / or, the cellulase comprises a complex cellulase derived from fungi, wherein the fungi include at least one of Trichoderma reesei, Trichoderma viride, Trichoderma koningii, and Aspergillus niger.

4. The biodegradable composite material as described in claim 1, characterized in that, The lipase treatment is carried out in a first solution containing lipase and with a pH of 7.0 to 9.0; And / or, the cellulase treatment is carried out in a second solution containing cellulase and having a pH of 4.0 to 6.

0.

5. The biodegradable composite material according to any one of claims 1-4, characterized in that, The biodegradable copolyester includes at least one of polybutylene terephthalate, polybutylene succinate, polycaprolactone, and poly(3-hydroxybutyrate-3-hydroxyhexanoate). And / or, the grafting agent includes at least one of acrylonitrile, methyl methacrylate, maleic anhydride, phthalic anhydride, and silane coupling agent.

6. A method for preparing a biodegradable composite material, characterized in that, include: Provide raw material components in parts by weight of the biodegradable composite material as described in any one of claims 1-5; The coconut shell powder, polylactic acid, biodegradable copolyester, cellulose nanocrystals, and grafting agent are melt-blended to obtain a compound material. The mixed materials are processed and shaped to obtain the biodegradable composite material.

7. The preparation method according to claim 6, characterized in that, The preparation steps of the coconut shell powder include: After the coconut shell raw material is cut into coconut shell fragments and washed with water, it is first soaked in a first solution containing lipase and with a pH value of 7.0~9.0 for a first soaking treatment, then soaked in a second solution containing cellulase and with a pH value of 4.0~6.0 for a second soaking treatment, and finally dried and crushed to obtain the coconut shell powder.

8. The preparation method according to claim 7, characterized in that, The size of the coconut shell fragments is 5cm to 7cm; And / or, the temperature of the water washing is 25℃~40℃; And / or, the mass fraction of the lipase in the first solution is 0.6%~0.8%; And / or, the temperature of the first soaking treatment is 10℃~45℃, and the time is 2h~5h; And / or, the mass fraction of the cellulase in the second solution is 0.1% to 0.7%; And / or, the temperature of the second soaking treatment is 10℃~50℃, and the time is 2h~5h; And / or, the drying process is carried out at a temperature of 80℃~105℃ for a time of 24h~48h.

9. The preparation method according to any one of claims 6-8, characterized in that, The melting and mixing temperature is 120℃~170℃, and the time is 14h~20h; And / or, the processing and molding includes: first crushing the mixed material into particles with a size range of 2.0mm to 3.0mm, and then placing the particles in a mold for molding.

10. A heating device, characterized in that, The device includes a shell, the material of which includes the biodegradable composite material according to any one of claims 1-5 or the biodegradable composite material prepared by the preparation method according to any one of claims 6-9.

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