A biodegradable product based on chitin micro-nano fiber membrane and preparation method thereof

Abstract

The present invention provides a degradable product based on chitin micro-nano fiber membrane and a preparation method thereof, and obtains purified chitin fiber and chitin micro-nano fiber wet membrane; then gelation and step-by-step neutralization treatment are carried out using an alkaline solution under low temperature conditions, or sodium periodate is used for gelation. Chitin micron fibers and chitin nanofibers are extracted from biomass shell raw materials such as shrimp and crab shells through a mechanical graded fiber disintegration process and mixed and interwoven. The chitin nanofibers strengthen the bonding force between the chitin micron fiber networks, and construct a stable three-dimensional ultrafine multi-level hierarchical double network structure through gelation, retaining and enhancing the advantages of the chitin micron fiber network and the chitin nanofiber network, with excellent mechanical properties, good light transmittance, thermal stability, water resistance, etc., and have potential application prospects in the fields of precision optical devices, flexible electronic devices, and high-performance all-biomass "glue-free self-adhesive" degradable packaging.

Description

Technical Field

[0001] The invention relates to the field of material, in particular to a degradable product based on chitin micro-nano fiber membrane and a preparation method thereof. Background Art

[0002] Plastics have the advantages of being lightweight, low in manufacturing cost, and easy to shape. They also have excellent optical properties and water resistance. However, in recent years, the environmental pollution caused by disposable petroleum-based plastic packaging has attracted much attention. Due to the difficulty of degrading petroleum-based plastics and the current low recycling rate, these petroleum-based plastic wastes have become one of the main factors causing environmental pollution.

[0003] The degradable plastics currently developed mainly include polylactic acid (PLA), polycaprolactone (PCL), polyhydroxybutyrate (PHB), etc. Among them, PLA is mainly derived from food crops such as corn. Although it is biodegradable, the degradation conditions are relatively harsh and it is difficult to achieve natural degradation. Secondly, using corn as the main raw material for plastic production will inevitably consume a large amount of corn and raise food prices. In addition, PLA also has problems such as heat resistance, UV resistance, brittle texture, and inability to form films, and the preparation process is relatively complicated. Compared with PLA, PCL has better hydrophobicity, but slower degradation rate, low melting point, low molecular weight, and poor strength, making it difficult to further expand its application field. PHB has a large relative density, low oxygen permeability, UV tolerance, active optical activity, but it is fragile and has poor impact resistance. Its processing conditions are harsh, the processing temperature is a narrow temperature range near 190°C, and the molten state is extremely unstable and prone to degradation. These problems limit the further development and diversified application of existing degradable plastics.

[0004] Therefore, it is of great significance to develop a new green and environmentally friendly plastic alternative that has high strength, optical transparency, heat resistance, water resistance, and is fully biodegradable. Summary of the invention

[0005] The present invention aims to provide a degradable product based on chitin micro-nano fiber membrane and a preparation method thereof, wherein chitin micron fiber and chitin nanofiber are extracted from biological shell materials such as shrimp and crab shells through a mechanical graded fiber disintegration process and mixed and interwoven. Among them, the chitin nanofiber strengthens the bonding force between the chitin micron fiber network, forming a stable three-dimensional ultrafine multi-level graded double network structure, retaining and enhancing the advantages of the chitin micron fiber network and the chitin nanofiber network, with excellent mechanical properties, good light transmittance, thermal stability and water resistance, and has potential application prospects in the fields of precision optical devices, flexible electronic devices, and high-performance all-biomass degradable packaging.

[0006] To achieve the above object, the present invention proposes the following technical solution: a method for preparing a degradable product based on chitin micro-nano fiber membrane, comprising the following process:

[0007] The first step is to take the biomass crustacean raw material, fully wash it with deionized water, then perform calcium carbonate removal and step-by-step protein removal, then perform depigmentation treatment with a decolorizing solution, and then wash it to neutrality to obtain purified chitin fiber;

[0008] The second step is to mechanically defibrinate the chitosan fibers to obtain chitosan micron fibers with a diameter of 100-300 nm and a length of 5-20 μm and chitosan nanofibers with a diameter of 5-50 nm and a length of 0.1-1 μm, respectively; dilute the chitosan micron fibers and chitosan nanofibers in an acid solution with a pH value of 3-4, and fully mix them by ultrasonic treatment according to different mass ratios to obtain a uniform mixed slurry; perform film-forming treatment on the mixed slurry to prepare a chitosan micro-nano fiber wet film;

[0009] The third step is to use 15-25% alkaline solution at a low temperature of minus 18-25°C for gelation and step-by-step neutralization treatment. The alkaline solution is sodium hydroxide NaOH or potassium hydroxide KOH. The specific method of gelation and step-by-step neutralization treatment is: the chitosan micro-nano fiber wet film obtained in the second step is immersed in 15-25% alkaline solution at a low temperature of minus 18-25°C for 12-24 hours to induce gelation of the chitosan micro-nano fiber. Then, under the low temperature of minus 18-25°C, ice ethanol is used to partially remove the sodium (Na + ) ions for 2 hours, and then rinse the wet film with ice water until it is neutral, and dry it at room temperature to prepare chitosan micro-nano fiber hybrid membrane product a;

[0010] The third step is to cut the chitosan micro-nano fiber wet film obtained in the second step into rectangular strips of set size, roll them on a polytetrafluoroethylene cylindrical rod along the length edge, press them at the bonding edge, and then place them in a 15-25% alkaline solution, and immerse them at a low temperature of minus 18-25°C for 12-24 hours to induce gelation of the chitosan micro-nano fibers, and then use ice ethanol to partially remove the sodium (Na + ) ions for 2 hours, then rinse the wet film with ice water until it is neutral, dry it at room temperature for 2-6 hours and then demould it to obtain a straw product;

[0011] The third step is to place the chitosan micro-nano fiber wet film obtained in the second step in a 1-3% sodium periodate solution, treat it at 25-40° C. in a dark environment for 2-6 hours, and then fully wash and dry it, so as to prepare a chitosan micro-nano fiber film product b with excellent water resistance;

[0012] Alternatively, the third step is to dry the chitosan micro-nano fiber wet film obtained in the second step to obtain a chitosan micro-nano fiber film c product.

[0013] The third step is to form and dry the chitosan micro-nano fiber wet film obtained in the second step. The forming process includes rolling or folding, and a series of chitosan micro-nano fiber film glue-free self-adhesive forming products d can be prepared.

[0014] Furthermore, in the present invention, the specific method of the first step is to take biomass crustacean raw materials such as shrimp and crab shells, fully wash them with deionized water, soak and stir them in 5-8% hydrochloric acid solution for 24-48 hours at room temperature of 20-35°C, decalcify them, and then thoroughly wash them with deionized water to neutrality to obtain standard sample 1, soak standard sample 1 in 3-20% alkaline solution for 1-3 weeks, perform step-by-step deproteinization treatment at room temperature, and then thoroughly wash them with deionized water to neutrality to obtain standard sample 2, depigment standard sample 2 with a decolorization solution, and then wash them to neutrality to obtain purified chitin fiber.

[0015] Further, in the present invention, during the step-by-step deproteinization process, the alkaline solution can be selected from sodium hydroxide NaOH or potassium hydroxide KOH; the step-by-step deproteinization process is specifically as follows: 3-4% alkaline solution is used in the first week, 8-10% alkaline solution is used in the second week, and 15-20% alkaline solution is used in the third week for step-by-step deproteinization;

[0016] The decolorizing solution is selected from ethanol or hydrogen peroxide.

[0017] Furthermore, in the present invention, the mechanical method in the second step includes mechanical stirring, ultrafine grinding, ultrasonic crushing, high-pressure homogenization and high-speed centrifugation. Before the mechanical method is used for defibration, the chitosan fiber is diluted to 0.1-1%;

[0018] Mechanical stirring processing parameters: power 400-500W, speed 450-600 rpm;

[0019] Ultrafine grinding processing parameters: the upper and lower grinding discs of the grinding machine are set to have a spacing of -0.20 to -0.35 mm, the grinding disc speed is 1600-1800 r / min, and the number of grinding times is 1-2 times;

[0020] Ultrasonic disruption treatment parameters: power 800-1250W, ultrasonic time 10-20min;

[0021] High-pressure homogenization processing parameters: pressure is 1000-1500Pa, homogenization time is 30min;

[0022] High-speed centrifugation processing parameters: rotation speed is 10000-18000rmp / min, centrifugation time is 10 minutes, and the clear liquid above is collected.

[0023] Furthermore, in the present invention, the chitosan micron fiber is obtained by mechanical stirring, and the chitosan nanofiber can be obtained by ultrafine grinding, ultrasonic crushing, high-pressure homogenization and high-speed centrifugation, any one of which is used alone or in combination.

[0024] Furthermore, in the present invention, when a uniform mixed slurry is obtained in the second step, the mass ratios of the chitosan micron fiber to the chitosan nanofiber are 1:1, 7:3, and 3:7, respectively. During the ultrasonic process, the chitosan nanofiber suspension is dropwise added into the chitosan micron fiber suspension. The ultrasonic power is 800-1250 W and the ultrasonic time is 5-10 min.

[0025] Furthermore, in the present invention, the specific method of the film-forming treatment in the second step is: placing a microporous filter membrane with a diameter of 0.1-0.35 μm in a sand core funnel of a vacuum filter, and then vacuum filtering the uniformly mixed slurry.

[0026] Furthermore, in the present invention, the specific method of drying treatment can be room temperature drying, hot press drying or freeze drying;

[0027] Drying at room temperature includes drying the wet chitosan micro-nano fiber film obtained in the second step at a room temperature of 20-35° C. for 24-48 hours;

[0028] Hot pressing and drying includes covering the two sides of the chitosan micro-nano fiber wet film obtained in the second step with a fine steel mesh, filter paper, and a glass plate respectively, pressing the film flat, placing the film in a press at 110° C. and 0.5-2 MPa, hot pressing for 10-20 minutes, and then cooling the film at room temperature for 2 hours;

[0029] The vacuum drying process includes covering both sides of the wet chitosan micro-nanofiber film obtained in the second step with a fine steel mesh, filter paper, and a glass plate in sequence, pressing the film flat, and placing the film in a freeze dryer for drying for 12 hours.

[0030] Furthermore, in the present invention, the specific method of the rolling, folding and forming process in the third step is:

[0031] The chitosan micro-nanofiber wet film obtained in the second step is cut into rectangular strips of a certain size, rolled onto a polytetrafluoroethylene cylindrical rod along its length edge, pressed at the bonding edge, and demolded after drying at room temperature for 2-6 hours to obtain a straw product, which has the characteristic that no adhesive is required during the molding process.

[0032] The chitosan micro-nanofiber wet film obtained in the second step is cut into rectangular strips of a certain size, folded according to the shape of the packaging bag, and the edges are pressed and bonded, and dried at room temperature to obtain a packaging bag. The packaging bag has the characteristic that no adhesive is required during the molding process.

[0033] Furthermore, in the present invention, a degradable product based on chitin micro-nano fiber film is used as a packaging box, a packaging bag, a straw or a substrate material for a flexible electronic device.

[0034] Beneficial effects: The technical solution of this application has the following technical effects:

[0035] 1. The chitosan nanofibers in the present invention strengthen the bonding force between chitosan micron fibers, construct a stable high-strength three-dimensional ultrafine multi-level hierarchical double network structure, and achieve the synergistic enhancement of the mechanical properties of the chitosan micron fiber network and the chitosan nanofiber network. Compared with existing petrochemical-based plastics, it has both superior mechanical properties and biodegradability.

[0036] 2. Chitosan nanofibers are evenly dispersed among chitosan micron fibers, and through dense hydrogen bonding and bonding, they form an interwoven high-strength network structure with excellent optical transparency, and can be used in the field of transparent substrates for precision optical devices and flexible electronic devices.

[0037] 3. The chitosan micro-nano fiber wet film of the present invention utilizes a sodium hydroxide or sodium periodate gelation system, which can further increase the crosslinking density of the chitosan micron fiber and the chitosan nanofiber three-dimensional network, thereby improving the water resistance of the chitosan micro-nano fiber film without adding any waterproofing agent, and solving the problem of softening and rotting of the chitosan micro-nano fiber film when exposed to water.

[0038] 4. The chitosan micro-nano fiber wet film of the present invention utilizes a sodium hydroxide and sodium periodate gelation system to further increase the crosslinking density of the chitosan micron fiber and the chitosan nanofiber three-dimensional network, thereby enhancing the interaction between the fibers. Without adding any adhesive, it can achieve glue-free self-adhesive molding to prepare degradable packaging products such as straws, packaging bags, packaging boxes, etc.

[0039] 5. The chitosan micro-nano fiber membrane of the present invention can be processed into diversified products of different shapes and sizes according to engineering requirements, and has good processability to meet the needs of practical applications.

[0040] 6. The chitosan micro-nano fiber membrane in the present invention has a low density and is light in material, and has significant advantages in practical applications, especially in the field of transportation, and can effectively improve transportation efficiency and reduce transportation costs.

[0041] 7. The chitosan micro-nano fiber membrane of the present invention has a low thermal expansion coefficient and can maintain a relatively stable shape at 200°C. It has better thermal properties than existing petrochemical-based structural materials and can be used in the manufacture of precision equipment.

[0042] 8. The dense micro-nano fiber structure in the present invention enables the prepared material to have certain flame retardancy and self-extinguishing properties, and can be applied in the field of flame retardant materials.

[0043] 9. The raw material of the chitosan micro-nano fiber membrane in the present invention is shrimp and crab shells, which are inexhaustible renewable resources in nature. The chitosan micro-nano fiber membrane and its diversified products can be directly and completely degraded by microorganisms in the soil.

[0044] 10. The double network structure of the chitosan micro-nano fiber membrane in the present invention allows the membrane to be restored to its original integrity after being completely folded and rolled, and has high flexibility, and is expected to become a high-performance, environmentally friendly alternative membrane material.

[0045] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered to be part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

[0046] The foregoing and other aspects, embodiments and features of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned from the practice of the specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0048] Figure 1 This is a sample photo of the chitosan micro-nano fiber membrane of Example 1 of the present invention.

[0049] Figure 2 These are the stress-strain curves of the chitosan micro-nano fiber membrane of Example 1, the chitosan micron fiber membrane of Comparative Example 1, and the chitosan nanofiber membrane of Comparative Example 2 in a dry state.

[0050] Figure 3 These are the stress-strain curves of the chitosan micro-nano fiber membrane of Example 1, the chitosan micron fiber membrane of Comparative Example 1, and the chitosan nanofiber membrane of Comparative Example 2 under water absorption saturation state in the present invention.

[0051] Figure 4 The stress-strain curves of the chitosan micro-nano fiber membrane of Example 1, Example 4 and Example 5 in the present invention under the water absorption saturation state.

[0052] Figure 5 This is a light transmittance curve of the chitosan micro-nano fiber membrane in Example 1 of the present invention.

[0053] Figure 6 This is a two-dimensional code obtained by conventional printing of the chitosan micro-nano fiber membrane in Example 1 of the present invention.

[0054] Figure 7 The chitosan micro-nano fiber membrane in Example 1 of the present invention is used to prepare a degradable straw by self-adhesive molding without adding any adhesive.

[0055] Figure 8 The degradation of the degradable straw made of chitosan micro-nano fiber membrane in Example 1 of the present invention under natural environment.

[0056] Fig. 9 Schematic diagram of Example 1 of the present invention wherein the chitosan micro-nano fiber membrane (ChMNF) and polystyrene (PLA), polyethylene (PE), and polypropylene (PP) are heated to 250°C.

[0057] Fig.10 This is a photo of the results of the combustion test of the chitin micro-nano fiber membrane in Example 1 of the present invention. DETAILED DESCRIPTION

[0058] In order to better understand the technical content of the present invention, specific embodiments are cited and described as follows in conjunction with the accompanying drawings. Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, in which many illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily defined to include all aspects of the present invention. It should be understood that the various concepts and embodiments introduced above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed in the present invention are not limited to any implementation. In addition, some aspects disclosed in the present invention can be used alone, or in any appropriate combination with other aspects disclosed in the present invention.

[0059] Example 1: Chitosan microfiber and nanofiber mixing ratio 1:1

[0060] 1. Take shrimp and crab shells and other biomass crustacean raw materials, wash them thoroughly with deionized water, soak and stir them in 8% hydrochloric acid solution at room temperature of 25°C for 24 hours to decalcify, and then wash them thoroughly with deionized water until neutral to obtain standard sample 1.

[0061] 2. Standard sample 1 was deproteinized step by step using 4% NaOH in the first week, 10% NaOH in the second week, and 15% NaOH in the third week, and then thoroughly washed with deionized water until neutral, to obtain standard sample 2.

[0062] 3. Depigment the standard sample 2 with an ethanol solution, and then wash it to neutrality to obtain purified chitin fiber.

[0063] 4. The chitosan fibers were diluted to 1%, and the chitosan fibers were defibrated using a mechanical stirring method (processing parameters: power 500 W, rotation speed 600 rpm, processing 15 min) to obtain chitosan micron fibers with a diameter of 100-150 nm and a length of 5-10 μm.

[0064] 5. Dilute the chitosan micron fiber to obtain a chitosan micron fiber suspension. Grind twice using the ultrafine grinding method (the upper and lower grinding discs of the grinder are set to a spacing of -0.20 mm, and the grinding disc speed is 1800 r / min), and then homogenize for 30 minutes using a high-pressure homogenizer (pressure of 1500 Pa) to obtain chitosan nanofibers with a diameter of 5-10 nm and a length of 0.1-0.3 μm.

[0065] 6. The chitosan microfibers and chitosan nanofibers were diluted in an acid solution with a pH value of 3-4, and ultrasonically treated in a ratio of 1:1 (power of 1250 W, ultrasonic time of 5 min). During the ultrasonic process, the chitosan nanofiber suspension was added dropwise to the chitosan microfiber suspension to obtain a uniform mixed slurry.

[0066] 7. Place a microporous filter membrane with a diameter of 0.1 μm in the sand core funnel of a vacuum filter, and perform vacuum filtration on the mixed slurry to prepare a chitosan micro-nano fiber wet membrane.

[0067] 8. Cover both sides of the wet film obtained in step 7 with a fine steel mesh, filter paper, and glass plate respectively, press it flat, place it in a press at 110°C, 0.5MPa, hot press for 20 minutes, and then cool it at room temperature for 2 hours to obtain a chitosan micro-nano fiber membrane.

[0068] 9. The mechanical properties of the chitosan micro-nano fiber membrane were characterized by using a universal mechanical testing machine. The specific test conditions are: the membrane to be tested was cut into strips with a width of 5 mm and a length of 35 mm, the loading speed of the universal mechanical testing machine (Model 3365; Instron Corp., Canton, MA) was set to 2 mm / min, and the tensile strength and elongation at break of the test sample were tested. The tensile performance test results showed that the elongation at break was 2.81% and the tensile strength was 227.02 MPa. The transmittance and haze of the prepared chitosan micro-nano fiber membrane were characterized by using an ultraviolet visible near-infrared spectrophotometer (U-4100, HITACHI, Japan). The sample membrane to be tested was placed in the instrument and fixed in a position close to the integrating sphere. During the test, the wavelength range was set between 400 nm and 800 nm, and the scanning speed was 300 nm / min. The data with a wavelength of 600 nm were selected as the transmittance and haze values ​​of the sample. The test results show that the light transmittance is 89.1% and the haze is 18.1%.

[0069] 10. The 35mm×5mm film specimen to be tested was completely immersed in water for 2 hours, and the mechanical properties of the wet chitin micro-nanofiber membrane specimen were characterized using a universal mechanical testing machine. The specific test conditions are: the universal mechanical testing machine (Model 3365; Instron Corp., Canton, MA) has a loading speed of 2mm / min, and the tensile strength and elongation at break of the test sample are tested. The tensile performance test results show that the elongation at break is 2.91%, the tensile strength is 28.64MPa, and the water resistance is good.

[0070] Example 2: Chitosan microfiber and nanofiber mixing ratio 7:3

[0071] 1. Take shrimp and crab shells and other biomass crustacean raw materials, wash them thoroughly with deionized water, soak and stir them in 5% hydrochloric acid solution at room temperature of 25°C for 48 hours to decalcify, and then wash them thoroughly with deionized water until neutral to obtain standard sample 1.

[0072] 2. Standard sample 1 was deproteinized step by step using 3% NaOH in the first week, 8% NaOH in the second week, and 20% NaOH in the third week, and then thoroughly washed with deionized water until neutral, to obtain standard sample 2.

[0073] 3. Depigment the standard sample 2 with a hydrogen peroxide solution, and then wash it until it reaches neutrality to obtain purified chitin fiber.

[0074] 4. The chitosan fibers were diluted to 0.1%, and the chitosan fibers were defibrated by mechanical stirring (processing parameters: power 400 W, rotation speed 450 rpm, processing 15 min) to obtain chitosan micron fibers with a diameter of 150-200 nm and a length of 10-15 μm.

[0075] 5. Dilute the chitosan micron fiber to obtain a chitosan micron fiber suspension. Grind once using the ultrafine grinding method (the upper and lower grinding discs of the grinder are set to a spacing of -0.20 mm, and the grinding disc speed is 1800 r / min), and then homogenize for 30 minutes using a high-pressure homogenizer (pressure of 1250 Pa) to obtain chitosan nanofibers with a diameter of 15-30 nm and a length of 0.3-0.5 μm.

[0076] 6. The chitosan microfibers and chitosan nanofibers were diluted in an acid solution with a pH value of 3-4, and ultrasonically treated in a ratio of 7:3 (power of 800 W, ultrasonic time of 10 min). During the ultrasonic process, the chitosan nanofiber suspension was added dropwise to the chitosan microfiber suspension to obtain a uniform mixed slurry.

[0077] 7. Place a microporous filter membrane with a diameter of 0.2 μm in the sand core funnel of a vacuum filter, and perform vacuum filtration on the mixed slurry to prepare a chitosan micro-nano fiber wet membrane.

[0078] 8. Cover both sides of the wet film obtained in step 7 with a fine steel mesh, filter paper, and glass plate respectively, press it flat, place it in a press at 110°C, 0.5MPa, hot press for 20 minutes, and then cool it at room temperature for 2 hours to obtain a chitosan micro-nano fiber membrane.

[0079] 9. The mechanical properties of the chitosan micro-nano fiber membrane were characterized by using a universal mechanical testing machine. The specific test conditions are: the membrane to be tested was cut into strips with a width of 5 mm and a length of 35 mm, the loading speed of the universal mechanical testing machine (Model 3365; Instron Corp., Canton, MA) was set to 2 mm / min, and the tensile strength and elongation at break of the test sample were tested. The tensile performance test results showed that the elongation at break was 2.3% and the tensile strength was 110 MPa. The transmittance of the prepared chitosan micro-nano fiber membrane was characterized by using an ultraviolet visible near-infrared spectrophotometer (U-4100, HITACHI, Japan). The sample membrane to be tested was placed in the instrument and fixed in a position close to the integrating sphere. During the test, the wavelength range was set between 400 nm and 800 nm, and the scanning speed was 300 nm / min. The data with a wavelength of 600 nm was selected as the transmittance value of the sample. The test results showed that the transmittance was 84.3%.

[0080] Example 3: Chitosan micron and nanofiber mixing ratio 3:7

[0081] 1. Take shrimp and crab shells and other biomass crustacean raw materials, wash them thoroughly with deionized water, soak and stir them in 8% hydrochloric acid solution at room temperature of 25°C for 24 hours to decalcify, and then wash them thoroughly with deionized water until neutral to obtain standard sample 1.

[0082] 2. Standard sample 1 was deproteinized step by step using 3% KOH in the first week, 8% KOH in the second week, and 20% KOH in the third week, and then thoroughly washed with deionized water until neutral, to obtain standard sample 2.

[0083] 3. Depigment the standard sample 2 with a hydrogen peroxide solution, and then wash it until it reaches neutrality to obtain purified chitin fiber.

[0084] 4. The chitosan fibers were diluted to 0.5%, and the chitosan fibers were defibrated using a mechanical stirring method (processing parameters: power 400 W, rotation speed 450 rpm, processing 10 min) to obtain chitosan micron fibers with a diameter of 200-300 nm and a length of 15-20 μm.

[0085] 5. Dilute the chitosan microfibers to obtain a chitosan microfiber suspension, centrifuge for 10 minutes using a high-speed centrifugation method (rotation speed of 10,000 rpm), collect the clear liquid above, and obtain chitosan nanofibers with a diameter of 35-50 nm and a length of 0.7-1 μm.

[0086] 6. The chitosan microfibers and chitosan nanofibers were diluted in an acid solution with a pH value of 3-4, and ultrasonically treated in a ratio of 3:7 (power of 800 W, ultrasonic time of 10 min). During the ultrasonic process, the chitosan nanofiber suspension was added dropwise to the chitosan microfiber suspension to obtain a uniform mixed slurry.

[0087] 7. Place a microporous filter membrane with a diameter of 0.2 μm in the sand core funnel of a vacuum filter, and perform vacuum filtration on the mixed slurry to prepare a chitosan micro-nano fiber wet membrane.

[0088] 8. The wet film obtained in step 7 was dried at room temperature of 25°C for 24 hours to obtain a chitosan micro-nano fiber membrane.

[0089] 9. The mechanical properties of the chitosan micro-nano fiber membrane were characterized by using a universal mechanical testing machine. The specific test conditions are: the membrane to be tested was cut into strips with a width of 5 mm and a length of 35 mm, the loading speed of the universal mechanical testing machine (Model 3365; Instron Corp., Canton, MA) was set to 2 mm / min, and the tensile strength and elongation at break of the test sample were tested. The tensile performance test results showed that the elongation at break was 1.81% and the tensile strength was 124.21 MPa. The transmittance of the prepared chitosan micro-nano fiber membrane was characterized by using an ultraviolet visible near-infrared spectrophotometer (U-4100, HITACHI, Japan). The sample membrane to be tested was placed in the instrument and fixed in a position close to the integrating sphere. During the test, the wavelength range was set between 400 nm and 800 nm, and the scanning speed was 300 nm / min. The data with a wavelength of 600 nm was selected as the transmittance value of the sample. The test results showed that the transmittance was 87.2%.

[0090] Example 4: Further NaOH gelation treatment based on Example 1 (Chitosan micro-nano fiber hybrid membrane a product)

[0091] 1. Take shrimp and crab shells and other biomass crustacean raw materials, wash them thoroughly with deionized water, soak and stir them in 8% hydrochloric acid solution at room temperature of 25°C for 24 hours to decalcify, and then wash them thoroughly with deionized water until neutral to obtain standard sample 1.

[0092] 2. Standard sample 1 was deproteinized step by step using 4% NaOH in the first week, 10% NaOH in the second week, and 15% NaOH in the third week, and then thoroughly washed with deionized water until neutral, to obtain standard sample 2.

[0093] 3. Depigment the standard sample 2 with an ethanol solution, and then wash it until it reaches neutrality to obtain purified chitin fiber.

[0094] 4. The chitosan fibers were diluted to 1%, and the chitosan fibers were defibrated using a mechanical stirring method (processing parameters: power 500 W, rotation speed 600 rpm, processing 15 min) to obtain chitosan micron fibers with a diameter of 100-150 nm and a length of 5-10 μm.

[0095] 5. Dilute the chitosan micron fiber to obtain a chitosan micron fiber suspension. Grind twice using the ultrafine grinding method (the upper and lower grinding discs of the grinder are set to a spacing of -0.20 mm, and the grinding disc speed is 1800 r / min), and then homogenize for 30 minutes using a high-pressure homogenizer (pressure of 1500 Pa) to obtain chitosan nanofibers with a diameter of 5-10 nm and a length of 0.1-0.3 μm.

[0096] 6. The chitosan microfibers and chitosan nanofibers were diluted in an acid solution with a pH value of 3-4, and ultrasonically treated in a ratio of 1:1 (power of 1250 W, ultrasonic time of 5 min). During the ultrasonic process, the chitosan nanofiber suspension was added dropwise to the chitosan microfiber suspension to obtain a uniform mixed slurry.

[0097] 7. Place a microporous filter membrane with a diameter of 0.1 μm in the sand core funnel of a vacuum filter, and perform vacuum filtration on the mixed slurry to prepare chitosan micro-nano fiber wet membrane-1.

[0098] 8. The wet film obtained in step 7 was immersed in 20% NaOH solution at -18°C for 12 h to induce gelation of chitin micro-nanofibers. Then, the sodium (Na + ) ions for 2 hours, and then rinse the wet membrane with ice water until it is neutral. The two sides of the wet membrane are covered with a fine steel mesh, filter paper, and a glass plate respectively, and pressed flat. Place it in a press at 110°C, 0.5MPa, and hot press for 20 minutes, then cool it at room temperature for 2 hours to obtain chitosan micro-nano fiber membrane-2.

[0099] 9. The mechanical properties of the chitin micro-nano fiber membrane treated with NaOH gelation were characterized using a universal mechanical testing machine. The specific test conditions are: the membrane to be tested is cut into strips with a width of 5 mm and a length of 35 mm, the loading speed of the universal mechanical testing machine (Model 3365; Instron Corp., Canton, MA) is set to 2 mm / min, and the tensile strength and elongation at break of the test sample are tested. The tensile performance test results show that the elongation at break is 2.17% and the tensile strength is 113.39 MPa. The transmittance of the prepared chitin micro-nano fiber membrane is characterized using an ultraviolet visible near-infrared spectrophotometer (U-4100, HITACHI, Japan). The sample membrane to be tested is placed in the instrument and fixed in a position close to the integrating sphere. During the test, the wavelength range is set between 400 nm and 800 nm, and the scanning speed is 300 nm / min. The data with a wavelength of 600 nm is selected as the transmittance value of the sample. The test results show that the transmittance is 84.6%.

[0100] 10. The 35mm×5mm film sample to be tested was completely immersed in water for 2 hours, and the mechanical properties of the wet chitin micro-nanofiber film sample were characterized using a universal mechanical testing machine. The specific test conditions are: the universal mechanical testing machine (Model 3365; Instron Corp., Canton, MA) has a loading speed of 2mm / min, and the tensile strength and elongation at break of the test sample are tested. The tensile performance test results show that the elongation at break is 3.46%, the tensile strength is 50.32MPa, and the water resistance is significantly improved compared with Example 1, which is nearly 2 times higher.

[0101] Example 5: Further sodium periodate gelation treatment based on Example 1 (chitosan micro-nano fiber membrane product b)

[0102] 1. Take shrimp and crab shells and other biomass crustacean raw materials, wash them thoroughly with deionized water, soak and stir them in 8% hydrochloric acid solution at room temperature of 25°C for 24 hours to decalcify, and then wash them thoroughly with deionized water until neutral to obtain standard sample 1.

[0103] 2. Standard sample 1 was deproteinized step by step using 4% NaOH in the first week, 10% NaOH in the second week, and 15% NaOH in the third week, and then thoroughly washed with deionized water until neutral, to obtain standard sample 2.

[0104] 3. Depigment the standard sample 2 with an ethanol solution, and then wash it until it reaches neutrality to obtain purified chitin fiber.

[0105] 4. The chitosan fibers were diluted to 1%, and the chitosan fibers were defibrated using a mechanical stirring method (processing parameters: power 500 W, rotation speed 600 rpm, processing 15 min) to obtain chitosan micron fibers with a diameter of 100-150 nm and a length of 5-10 μm.

[0106] 5. Dilute the chitosan micron fiber to obtain a chitosan micron fiber suspension. Grind twice using the ultrafine grinding method (the upper and lower grinding discs of the grinder are set to a spacing of -0.20 mm, and the grinding disc speed is 1800 r / min), and then homogenize for 30 minutes using a high-pressure homogenizer (pressure of 1500 Pa) to obtain chitosan nanofibers with a diameter of 5-10 nm and a length of 0.1-0.3 μm.

[0107] 6. The chitosan microfibers and chitosan nanofibers were diluted in an acid solution with a pH value of 3-4, and ultrasonically treated in a ratio of 1:1 (power of 1250 W, ultrasonic time of 5 min). During the ultrasonic process, the chitosan nanofiber suspension was added dropwise to the chitosan microfiber suspension to obtain a uniform mixed slurry.

[0108] 7. Place a microporous filter membrane with a diameter of 0.1 μm in the sand core funnel of a vacuum filter, and perform vacuum filtration on the mixed slurry to prepare chitosan micro-nano fiber wet membrane-1.

[0109] 8. Place the wet film obtained in step 7 in a 1% sodium periodate solution and treat it at 25°C in the dark for 6 hours, then wash it thoroughly. Cover both sides of the wet film with a fine steel mesh, filter paper, and glass plate respectively, press it flat, place it in a press at 110°C, 0.5MPa, hot press for 20 minutes, and then cool it at room temperature for 2 hours to obtain chitosan micro-nano fiber membrane-3.

[0110] 9. The mechanical properties of the chitosan micro-nano fiber membrane were characterized by using a universal mechanical testing machine. The specific test conditions are: the membrane to be tested was cut into strips with a width of 5 mm and a length of 35 mm, the loading speed of the universal mechanical testing machine (Model 3365; Instron Corp., Canton, MA) was set to 2 mm / min, and the tensile strength and elongation at break of the test sample were tested. The tensile performance test results showed that the elongation at break was 3.63% and the tensile strength was 198.25 MPa. The transmittance of the prepared chitosan micro-nano fiber membrane was characterized by using an ultraviolet visible near-infrared spectrophotometer (U-4100, HITACHI, Japan). The sample membrane to be tested was placed in the instrument and fixed in a position close to the integrating sphere. During the test, the wavelength range was set between 400 nm and 800 nm, and the scanning speed was 300 nm / min. The data with a wavelength of 600 nm was selected as the transmittance value of the sample. The test results showed that the transmittance was 82.5%.

[0111] 10. The 35mm×5mm film sample to be tested was completely immersed in water for 2 hours, and the mechanical properties of the wet chitin micro-nanofiber film sample were characterized using a universal mechanical testing machine. The specific test conditions are: the universal mechanical testing machine (Model 3365; Instron Corp., Canton, MA) has a loading speed of 2mm / min, and the tensile strength and elongation at break of the test sample are tested. The tensile performance test results show that the elongation at break is 3.42%, the tensile strength is 42.85MPa, and the water resistance is significantly improved compared with Example 1.

[0112] Comparative Example 1: Chitosan Microfiber Membrane

[0113] 1. Take shrimp and crab shells and other biomass crustacean raw materials, wash them thoroughly with deionized water, soak and stir them in 8% hydrochloric acid solution at room temperature of 25°C for 24 hours to decalcify, and then wash them thoroughly with deionized water until neutral to obtain standard sample 1.

[0114] 2. Standard sample 1 was deproteinized step by step using 4% NaOH in the first week, 10% NaOH in the second week, and 15% NaOH in the third week, and then thoroughly washed with deionized water until neutral, to obtain standard sample 2.

[0115] 3. Depigment the standard sample 2 with an ethanol solution, and then wash it until it reaches neutrality to obtain purified chitin fiber.

[0116] 4. The chitosan fibers were diluted to 1%, and the chitosan fibers were defibrated using a mechanical stirring method (processing parameters: power 500 W, rotation speed 600 rpm, processing 15 min) to obtain chitosan micron fibers with a diameter of 100-150 nm and a length of 5-10 μm.

[0117] 5. Dilute the chitosan microfibers to obtain a chitosan microfiber suspension. Place a microporous filter membrane with a diameter of 0.2 μm in a sand core funnel of a vacuum filter, and then perform vacuum filtration on the suspension to obtain a chitosan microfiber wet film.

[0118] 6. Cover both sides of the wet film obtained in step 5 with a fine steel mesh, filter paper, and glass plate respectively, press it flat, place it in a press at 110°C, 0.5MPa, hot press for 20 minutes, and then cool it at room temperature for 2 hours to obtain a chitosan microfiber membrane.

[0119] 7. The mechanical properties of the chitosan micron fiber membrane were characterized by using a universal mechanical testing machine. The specific test conditions are: the membrane to be tested was cut into strips with a width of 5 mm and a length of 35 mm, the loading speed of the universal mechanical testing machine (Model 3365; Instron Corp., Canton, MA) was set to 2 mm / min, and the tensile strength and elongation at break of the test sample were tested. The tensile performance test results showed that the elongation at break was 1.42% and the tensile strength was 109.37 MPa. The transmittance of the prepared chitosan micron fiber membrane was characterized by using an ultraviolet visible near-infrared spectrophotometer (U-4100, HITACHI, Japan). The sample membrane to be tested was placed in the instrument and fixed in a position close to the integrating sphere. During the test, the wavelength range was set between 400 nm and 800 nm, and the scanning speed was 300 nm / min. The data with a wavelength of 600 nm was selected as the transmittance value of the sample. The test results showed that the transmittance was 79.3%.

[0120] 8. The 35mm×5mm film specimen to be tested was completely immersed in water for 2 hours, and the mechanical properties of the wet chitin microfiber film specimen were characterized using a universal mechanical testing machine. The specific test conditions were: the universal mechanical testing machine (Model 3365; Instron Corp., Canton, MA) had a loading speed of 2mm / min, and the tensile strength and elongation at break of the test sample were tested. The tensile performance test results showed that the elongation at break was 2.98% and the tensile strength was 11.16MPa.

[0121] Comparative Example 2: Chitosan Nanofiber Membrane

[0122] 1. Take shrimp and crab shells and other biomass crustacean raw materials, wash them thoroughly with deionized water, soak and stir them in 8% hydrochloric acid solution at room temperature of 25°C for 24 hours to decalcify, and then wash them thoroughly with deionized water until neutral to obtain standard sample 1.

[0123] 2. Standard sample 1 was deproteinized step by step using 4% NaOH in the first week, 10% NaOH in the second week, and 15% NaOH in the third week, and then thoroughly washed with deionized water until neutral, to obtain standard sample 2.

[0124] 3. Depigment the standard sample 2 with an ethanol solution, and then wash it until it reaches neutrality to obtain purified chitin fiber.

[0125] 4. The chitosan fibers were diluted to 1%, and the chitosan fibers were defibrated using a mechanical stirring method (processing parameters: power 500 W, rotation speed 600 rpm, processing 15 min) to obtain chitosan micron fibers with a diameter of 100-150 nm and a length of 5-10 μm.

[0126] 5. Dilute the chitosan micron fiber to obtain a chitosan micron fiber suspension. Grind twice using the ultrafine grinding method (the upper and lower grinding discs of the grinder are set to a spacing of -0.20 mm, and the grinding disc speed is 1800 r / min), and then homogenize for 30 minutes using a high-pressure homogenizer (pressure of 1500 Pa) to obtain chitosan nanofibers with a diameter of 5-10 nm and a length of 0.1-0.3 μm.

[0127] 6. Dilute the chitosan nanofibers to obtain a chitosan nanofiber suspension. Place a microporous filter membrane with a diameter of 0.2 μm in a sand core funnel of a vacuum filter, and then perform vacuum filtration on the suspension to obtain a chitosan nanofiber wet film.

[0128] 7. Cover both sides of the wet film obtained in step 6 with a fine steel mesh, filter paper, and glass plate respectively, press it flat, place it in a press at 110°C, 0.5MPa, hot press for 20 minutes, and then cool it at room temperature for 2 hours to obtain a chitosan nanofiber membrane.

[0129] 8. The mechanical properties of the chitosan nanofiber membrane were characterized by using a universal mechanical testing machine. The specific test conditions are: the membrane to be tested was cut into strips with a width of 5 mm and a length of 35 mm, the loading speed of the universal mechanical testing machine (Model 3365; Instron Corp., Canton, MA) was set to 2 mm / min, and the tensile strength and elongation at break of the test sample were tested. The tensile performance test results showed that the elongation at break was 1.69% and the tensile strength was 128.83 MPa. The transmittance of the prepared chitosan nanofiber membrane was characterized by an ultraviolet-visible near-infrared spectrophotometer (U-4100, HITACHI, Japan). The sample membrane to be tested was placed in the instrument and fixed in a position close to the integrating sphere. During the test, the wavelength range was set between 400 nm and 800 nm, and the scanning speed was 300 nm / min. The data with a wavelength of 600 nm was selected as the transmittance value of the sample. The test results show that the transmittance is 89.9%.

[0130] 9. The 35mm×5mm film specimen to be tested was completely immersed in water for 2 hours, and the mechanical properties of the wet chitin nanofiber membrane specimen were characterized using a universal mechanical testing machine. The specific test conditions were: the universal mechanical testing machine (Model 3365; Instron Corp., Canton, MA) had a loading speed of 2mm / min, and the tensile strength and elongation at break of the test sample were tested. The tensile performance test results showed that the elongation at break was 2.82% and the tensile strength was 14.98MPa.

[0131] By comparing Example 1 with Comparative Example 1 and Comparative Example 2, it can be seen that due to the mixing of chitin micron fiber and chitin nanofiber, a stable ultrafine multi-scale dual network structure is formed, which retains and enhances the advantages of chitin micron fiber and chitin nanofiber network, so that the tensile strength of micro-nano fiber membrane is significantly improved, and the tensile strength is increased to 227.02MPa, while the tensile strength of chitin micron fiber membrane is 109.37MPa, and the tensile strength of chitin nanofiber membrane is 128.83MPa. The light transmittance of chitin micro-nano fiber hybrid membrane is 89.1%, which is close to the light transmittance of chitin nanofiber membrane (89.9%), and has excellent optical properties compared with chitin micron fiber membrane (79.3%), and is expected to be applied to the visual packaging film industry. Further gelation treatment can significantly improve the wet strength of the chitosan micro-nano fiber membrane (increased by nearly 2 times), and increase the crosslinking density of the three-dimensional network of chitosan micron fibers and chitosan nanofibers. This can improve the water resistance of the chitosan micro-nano fiber membrane without adding any waterproofing agents, and solve the problem of chitosan micro-nano fiber membrane softening when exposed to water.

[0132] The process parameters and performance data of each embodiment and comparative example are shown in the following table.

[0133]

[0134] Therefore, this embodiment can have the following beneficial effects:

[0135] 1. The chitosan nanofibers in the present invention strengthen the bonding between chitosan microfibers, forming a stable high-strength three-dimensional ultrafine multi-level hierarchical double network structure, achieving the synergistic enhancement of chitosan microfiber network and chitosan nanofiber network, and showing superior mechanical properties and biodegradability compared to existing petrochemical-based plastics, such as Figure 8 As shown, it can be completely degraded in the natural environment within 60 days.

[0136] 2. Chitosan nanofibers are evenly dispersed between chitosan micron fibers, and through dense hydrogen bonding and bonding, they form an interwoven high-strength network structure with good light transmittance, and can be used in the fields of precision optical devices and flexible electronic device substrates, such as Figure 6 shown.

[0137] 3. The chitosan micro-nano fiber wet film of the present invention utilizes a sodium hydroxide and sodium periodate gelation system to further increase the crosslinking density of the chitosan micron fiber and the chitosan nanofiber three-dimensional network, thereby improving the water resistance of the chitosan micro-nano fiber film without adding any waterproofing agent, and solving the problem of the chitosan micro-nano fiber film softening when exposed to water.

[0138] 4. The chitosan micro-nano fiber wet film of the present invention utilizes a sodium hydroxide and sodium periodate gelation system to further increase the crosslinking density of the chitosan micron fiber and the chitosan nanofiber three-dimensional network, thereby enhancing the interaction between the fibers. Without adding any adhesive, it can achieve glue-free self-adhesive molding to prepare degradable packaging products such as straws, packaging bags, packaging boxes, etc.

[0139] 5. The chitosan micro-nano fiber membrane of the present invention can be processed into diversified products of different shapes and sizes according to engineering requirements, and has good processability to meet the needs of practical applications.

[0140] 6. The chitosan micro-nano fiber membrane in the present invention has a low density and is light in material, and has significant advantages in practical applications, especially in the field of transportation, and can effectively improve transportation efficiency and reduce transportation costs.

[0141] 7. The chitosan micro-nano fiber membrane of the present invention has high thermal stability, such as Fig. 9 As shown, it can maintain a stable shape at 200°C, has better thermal properties than existing petrochemical-based structural materials, and can be used in precision equipment manufacturing.

[0142] 8. The dense micro-nano fiber structure in the present invention makes the prepared material have certain flame retardancy and can quickly self-extinguish after ignition. Fig.10 shown.

[0143] 9. The raw material of the chitosan micro-nano fiber membrane in the present invention is shrimp and crab shells, which are inexhaustible renewable resources in nature. The chitosan micro-nano fiber membrane and its diversified products can be directly and completely degraded by microorganisms in the soil.

[0144] 10. The double network structure of the chitosan micro-nano fiber membrane in the present invention allows the membrane to be restored to its original integrity after being completely folded and rolled, and has high flexibility, and is expected to become a high-performance, environmentally friendly alternative membrane material.

[0145] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A method for preparing a biodegradable product based on chitosan micro-nano fiber membrane, characterized in that: The process includes the following: The first step is to take the biomass crustacean raw material, fully wash it with deionized water, then perform calcium carbonate removal and step-by-step protein removal, then perform depigmentation treatment with a decolorizing solution, and then wash it to neutrality to obtain purified chitin fiber; The second step is to mechanically defibrinate the chitosan fibers to obtain chitosan micron fibers with a diameter of 100-300 nm and a length of 5-20 μm and chitosan nanofibers with a diameter of 5-50 nm and a length of 0.1-1 μm, respectively. The chitosan micron fibers and chitosan nanofibers are diluted in an acid solution with a pH value of 3-4, and the chitosan micron fibers and chitosan nanofibers are fully mixed by ultrasonic treatment at a mass ratio of 1:1, 7:3 or 3:

7. During the ultrasonic treatment, the chitosan nanofiber suspension is added dropwise to the chitosan micron fiber suspension, the ultrasonic power is 800-1250 W, and the ultrasonic time is 5-10 min to obtain a uniform mixed slurry, and the mixed slurry is subjected to film-forming treatment to prepare a chitosan micro-nano fiber wet film. The third step is to use 15-25% alkaline solution at low temperature conditions of minus 18-25℃ for gelation and step-by-step neutralization treatment. The alkaline solution is sodium hydroxide solution or potassium hydroxide solution. The specific method of gelation and step-by-step neutralization treatment is: the chitosan micro-nano fiber wet film obtained in the second step is immersed in 15-25% alkaline solution at low temperature conditions of minus 18-25℃ for 12-24 hours to induce gelation of chitosan micro-nano fibers. Subsequently, at low temperature conditions of minus 18-25℃, ice ethanol is used to remove sodium ions in the wet film step by step for 2 hours, and then the wet film is rinsed with ice water until it is neutral. Dry at room temperature to prepare chitosan micro-nano fiber mixed membrane a product.

2. The method for preparing a biodegradable product based on chitosan micro-nano fiber membrane according to claim 1, characterized in that: The third step is replaced by the following steps: the chitosan micro-nano fiber wet film obtained in the second step is cut into rectangular strips of set sizes, rolled on a polytetrafluoroethylene cylindrical rod along its length edge, pressed at the bonding edge, and then placed in a 15-25% alkaline solution. It is immersed in a low temperature condition of -18-25°C for 12-24 h to induce gelation of the chitosan micro-nano fibers. Subsequently, the sodium ions in the wet film are partially removed by ice ethanol at a low temperature condition of -18-25°C for 2 h. The wet film is then rinsed with ice water until it is neutral, dried at room temperature for 2-6 h, and then demolded to obtain a straw product.

3. The method for preparing a biodegradable product based on chitosan micro-nano fiber membrane according to claim 1, characterized in that: The third step is replaced by the following step: placing the chitosan micro-nano fiber wet film obtained in the second step in a 1-3% sodium periodate solution, treating it at 25-40° C. in a dark environment for 2-6 hours, and then washing and drying it thoroughly to prepare a chitosan micro-nano fiber film product b; Alternatively, the third step may be replaced by the following step, wherein the chitosan micro-nano fiber wet film obtained in the second step is dried to obtain a chitosan micro-nano fiber film product c; Or the third step can be replaced by the following steps: the chitosan micro-nano fiber wet film obtained in the second step is molded and dried, and the molding process includes rolling or folding to prepare the chitosan micro-nano fiber film glue-free self-adhesive molding product d product.

4. The method for preparing a biodegradable product based on chitosan micro-nano fiber membrane according to claim 1, characterized in that: The specific method of the first step is to take shrimp and crab shell biomass crustacean raw materials, fully wash them with deionized water, soak and stir them in 5-8% hydrochloric acid solution for 24-48 hours at room temperature of 20-35°C, decalcify, and then thoroughly wash them with deionized water to neutrality to obtain standard sample 1, soak standard sample 1 in 3-20% alkaline solution for 1-3 weeks, perform step-by-step deproteinization treatment at room temperature, and then thoroughly wash them with deionized water to neutrality to obtain standard sample 2, depigment standard sample 2 with a decolorization solution, and then wash them to neutrality to obtain purified chitin fiber.

5. The method for preparing a biodegradable product based on chitosan micro-nano fiber membrane according to claim 4, characterized in that: In the step-by-step deproteinization process, the alkaline solution is selected from sodium hydroxide solution or potassium hydroxide solution; the step-by-step deproteinization process is specifically as follows: 3-4% alkaline solution is used in the first week, 8-10% alkaline solution is used in the second week, and 15-20% alkaline solution is used in the third week for step-by-step deproteinization; The decolorizing solution is selected from ethanol or hydrogen peroxide.

6. The method for preparing a biodegradable product based on chitosan micro-nano fiber membrane according to claim 1, characterized in that: In the second step, the mechanical method includes mechanical stirring, ultrafine grinding, ultrasonic crushing, high-pressure homogenization and high-speed centrifugation. Before the mechanical method of defibration, the chitosan fiber is diluted to 0.1-1%; Mechanical stirring processing parameters: power 400-500W, speed 450-600 rpm; Ultrafine grinding processing parameters: the upper and lower grinding discs of the grinding machine are set to a spacing of -0.20 to -0.35 mm, the grinding disc speed is 1600-1800 r / min, and the number of grinding times is 1-2 times; Ultrasonic disruption treatment parameters: power 800-1250W, ultrasonic time 10-20min; High-pressure homogenization processing parameters: pressure is 1000~1500Pa, homogenization time is 30min; High-speed centrifugation processing parameters: rotation speed is 10000-18000r / min, centrifugation time is 10 minutes, and the clear liquid above is collected.

7. The method for preparing a biodegradable product based on chitosan micro-nano fiber membrane according to claim 1, characterized in that: The specific method of the film-forming treatment in the second step is: placing a microporous filter membrane with a diameter of 0.1-0.35 μm in the sand core funnel of the vacuum filter, and then vacuum filtering the evenly mixed slurry.

8. The method for preparing a degradable product based on chitosan micro-nano fiber membrane according to claim 3, characterized in that: The specific method of drying treatment is room temperature drying, hot press drying or freeze drying; Drying at room temperature includes drying the wet chitosan micro-nano fiber film obtained in the second step at a room temperature of 20-35° C. for 24-48 hours; Hot pressing and drying includes covering the two sides of the chitosan micro-nano fiber wet film obtained in the second step with a fine steel mesh, filter paper, and a glass plate respectively, pressing the film flat, placing the film in a press at 110° C. and 0.5-2 MPa, hot pressing for 10-20 minutes, and then cooling the film at room temperature; The vacuum drying process includes covering both sides of the wet chitosan micro-nanofiber film obtained in the second step with a fine steel mesh, filter paper, and a glass plate in sequence, pressing the film flat, and placing the film in a freeze dryer for 12 h.

9. The method for preparing a biodegradable product based on chitosan micro-nano fiber membrane according to claim 8, characterized in that: The specific method of the rolling, folding and forming process in the third step is: The chitosan micro-nano fiber wet film obtained in the second step is cut into rectangular strips of a certain size, rolled on a polytetrafluoroethylene cylindrical rod along the length edge, pressed at the bonding edge, and demolded after drying at room temperature for 2-6 hours to prepare a straw product, which is characterized in that no adhesive is required during the molding process; The chitosan micro-nanofiber wet film obtained in the second step is cut into rectangular strips of a certain size, folded according to the shape of the packaging bag, and the edges are pressed and bonded, and dried at room temperature to obtain the packaging bag, which is characterized in that no adhesive is required during the molding process.

10. Use of the degradable product prepared by the preparation method according to any one of claims 1, 3, 4, 5, 6, 7 or 8 in preparing packaging boxes, packaging bags, or flexible electronic device substrate materials.

Images