Degradable mulching film prepared by compounding starch wastewater with bamboo fibers and preparation method of degradable mulching film

Abstract

The invention discloses a degradable mulching film prepared by compounding starch wastewater with bamboo fibers and a preparation method of the degradable mulching film, and belongs to the technical field of agricultural mulching films. The mulching film is prepared from the following components in parts by weight: 75 to 90 parts of starch wastewater, 20 to 30 parts of bamboo fiber, 10 to 18 parts of polyvinyl alcohol, 18 to 30 parts of glycerol, 8 to 15 parts of cross-linking agent and 5 to 10 parts of filler. The defect that starch is difficult to form a film is effectively overcome, and powerful support is provided for application of biomass starch and bamboo fibers in the field of degradable plastics. In addition, starch wastewater is used as a raw material, so that the production cost can be reduced to a certain extent; the starch wastewater is used as process water of the bamboo fiber reinforced starch-based composite membrane, and the process can also counteract the treatment cost of the starch wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural mulch films, and in particular relates to a degradable mulch film made by compounding bamboo fiber with starch wastewater and a preparation method thereof. Background Art

[0002] Starch is an important industrial raw material, widely used in food, chemical, textile, medicine and other industries. The production of starch will produce a large amount of high-concentration acidic organic wastewater. Every ton of starch produced will produce 10-20m 3 The main components of starch wastewater are soluble starch, pentosan, ash and a small amount of protein. Although starch wastewater is generally non-toxic, discharging wastewater directly into environmental water bodies is not only a waste of water resources, but also causes serious damage to the environment. At present, the comprehensive utilization of starch wastewater at home and abroad is mainly reflected in industrial products such as single-cell protein, edible fungi, microbial flocculants, and biological pesticides. These wastewaters mainly contain soluble starch, a small amount of protein, organic acids, dust, minerals and a small amount of oil, which are easy to corrupt and ferment, making the water body black and smelly. Discharge into rivers will consume dissolved oxygen in the water and promote the reproduction of algae and aquatic plants. When the amount of wastewater is large, the river will experience severe hypoxia, anaerobic corruption and stench, and aquatic animals may suffocate to death, posing a threat to the human living environment.

[0003] As one of the renewable bioresources, starch has become a petroleum-based plastic packaging material due to its low cost, high yield and biodegradability. It is also versatile, price competitive and applicable to various industries. The defects of starch-based materials such as difficulty in handling, brittleness, water sensitivity and poor mechanical strength have greatly hindered their use. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a degradable mulch film made of starch wastewater and bamboo fiber and a preparation method thereof to solve the above problems.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The invention provides a degradable mulch film made of starch wastewater and bamboo fiber and a preparation method thereof. The mulch film comprises, by weight, 75-90 parts of starch wastewater, 20-30 parts of bamboo fiber, 10-18 parts of polyvinyl alcohol, 18-30 parts of glycerol, 8-15 parts of a cross-linking agent and 5-10 parts of a filler.

[0007] Furthermore, the starch wastewater is at least one of potato starch wastewater, wheat starch wastewater, sweet potato starch wastewater, lotus root starch wastewater, corn starch wastewater, rice starch wastewater, and pea starch wastewater.

[0008] Furthermore, the cross-linking agent is glutaraldehyde, the filler is calcium carbonate, and the particle size of the bamboo fiber is 80-120 nm.

[0009] Furthermore, it also includes a method for preparing a degradable mulch film by combining starch wastewater with bamboo fiber, comprising the following steps:

[0010] S1, preliminarily treating starch wastewater and concentrating it to obtain concentrated starch water; adding glycerol to the concentrated starch water to prepare a slurry, and then stirring and gelatinizing under heating conditions to obtain a starch gelatinized slurry;

[0011] S2, ball-milling the bamboo fiber to obtain ball-milled bamboo fiber powder;

[0012] S3, starch gelatinization slurry is mixed with bamboo fiber powder, polyvinyl alcohol and filler are added in sequence and stirred to obtain membrane liquid;

[0013] S4, degassing the membrane liquid under vacuum conditions to remove bubbles in the membrane liquid;

[0014] S5, adjusting the temperature and pH value of the membrane solution, and adding a cross-linking agent to carry out a cross-linking reaction;

[0015] S6. The mixed material is fed into an extruder and extruded into a ground film shape through a die; during extrusion, a heating device is used to solidify the ground film into shape.

[0016] Furthermore, in the step S1, the starch wastewater is treated by flotation separation, the starch wastewater is poured into a round-bottom flask equipped with a stirrer, and stirred at a temperature of 70-90° C. and a rotation speed of 200-400 r / min for 25-45 min.

[0017] Furthermore, in S2, the ball milling method is: the bamboo fiber is heated at 50-60°C for 3-5 hours to remove moisture, and the heated bamboo fiber is ball milled at a speed of 400-700rp / min using zirconium oxide ball milling beads. The ball milling time is 3-12 hours, and the mass ratio of bamboo fiber to zirconium oxide ball milling beads is 1:10.

[0018] Furthermore, in step S3, the membrane liquid is degassed under a vacuum condition of 0.01 MPa for 15-20 min.

[0019] Furthermore, in step S5, the temperature of the membrane liquid is 20-30° C., and the pH value is 4.5-9.5.

[0020] Furthermore, in step S6, the temperature of the heating device during extrusion is 45-55°C.

[0021] The beneficial effects of the present invention are:

[0022] 1. Since starch is a natural high molecular polymer with strong interaction between macromolecules, it is difficult to melt process the original starch, and the compatibility with other polymers in the blending process is also poor. Therefore, before preparing starch-based plastics, the starch must be chemically modified by chemical reaction to change its original structure, thereby changing the corresponding properties of the starch and turning the original starch into thermoplastic starch. In the present invention, starch wastewater and glycerol are used to prepare the slurry. During gelatinization and esterification, glycerol can weaken the interaction between starch molecules, improve the flexibility of the starch material, and make it easier to process and shape.

[0023] 2. Bamboo fiber cellulose extracted from naturally grown bamboo not only has good air permeability, instant water absorption, strong wear resistance and good dyeing properties, but also has natural antibacterial, antibacterial, mite removal, deodorization and UV resistance functions. When used as a reinforcing material for starch-based plastics, it can not only effectively improve the strength of starch-based plastics, but also has excellent environmental protection properties.

[0024] 3. The bamboo fiber pre-treated by ball mill, starch gelatinized slurry and polyvinyl alcohol are stirred evenly to form a membrane liquid. The starch gelatinized slurry will fully penetrate into the bamboo fiber, which is beneficial to the bonding and interweaving of the bamboo fiber, and can enhance the strength of the degradable plastic base film. The formation of the membrane liquid is conducive to the formation of a thin film base film by calendering at room temperature, and the plasticizer therein will give the starch thermoplasticity, which can fully thermally bond the bamboo fiber, effectively overcome the problem of difficult dispersion of the bamboo fiber, ensure the reinforcement effect of the bamboo fiber, and obtain a degradable plastic base film with uniformly dispersed bamboo fibers.

[0025] 4. The present invention proposes a method for preparing a bamboo fiber reinforced starch wastewater film, which uses starch wastewater as a raw material for starch slurry, and utilizes starch slurry to penetrate and bond bamboo fibers pretreated by ball milling to prepare a bamboo fiber reinforced starch wastewater film; the starch structure is destroyed by starch gelatinization and acidification, and the starch gelatinization slurry is given good viscosity, and the bamboo fibers are bonded and interwoven by the starch gelatinization slurry, so that the water resistance and strength of the film are further enhanced by the bamboo fibers; the bamboo fibers used have excellent mechanical properties and biocompatibility, and can be used as the skeleton of the film to improve the strength and stability of the film; through the action of a cross-linking agent, the bamboo fibers react chemically with organic matter in the starch wastewater to form a stable cross-linking structure, thereby improving the strength and durability of the ground film; the polyvinyl alcohol used has good film-forming properties and plasticity, and can be compounded with bamboo fibers and starch wastewater to form a uniform mixture, and a film product is obtained by extrusion molding; the glycerol used can be used to improve the flexibility and plasticity of the film; the calcium carbonate used can be used to adjust the transparency of the film, thereby further reducing the production cost.

[0026] 5. In the present invention, the preparation method adopted effectively overcomes the defect that starch is difficult to form into film, and provides strong support for the application of biomass starch and bamboo fiber in the field of degradable plastics. In addition, using starch wastewater as raw material can reduce production costs to a certain extent; using starch wastewater as process water for bamboo fiber reinforced starch-based composite film, this process can also offset the treatment cost of starch wastewater.

[0027] 6. The mulch film prepared by the present invention has high strength and good stiffness. It can be naturally degraded after use, reducing environmental pollution and ensuring the safety of the product. The film covering can inhibit soil moisture evaporation, increase soil temperature, promote crop growth, and reduce irrigation water consumption. At the same time, it provides a new idea for the resource utilization of starch wastewater.

[0028] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art may be taught from the practice of the present invention. The objectives and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to make the purpose, technical solution and beneficial effects of the invention clearer, the present invention provides the following drawings for illustration:

[0030] Figure 1 This is a scanning electron microscope image of the bamboo fiber reinforced starch wastewater film prepared by the present invention;

[0031] Figure 2 This is a scanning electron microscope image of the starch wastewater film prepared in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0032] Example 1

[0033] S1. Pour 80 parts of starch wastewater into a round-bottom flask equipped with a stirrer, stir at a speed of 300 r / min for 30 min at a temperature of 80°C, and then concentrate to 0.7 times to obtain concentrated starch water; add 22 parts of glycerol to the concentrated starch water to prepare a slurry, and then stir and gelatinize at 60°C to obtain a starch gelatinization slurry;

[0034] S2, heating 25 parts of bamboo fibers at 55° C. for 4 hours to remove moisture, and then ball milling at 550 rpm / min for 5 hours to obtain bamboo fiber powder with a particle size of 100 nm;

[0035] S3, starch gelatinization slurry is mixed with bamboo fiber powder, 14 parts of polyvinyl alcohol and 8 parts of calcium carbonate are added in sequence and stirred to obtain a membrane liquid;

[0036] S4, degassing the membrane liquid under vacuum conditions to remove bubbles in the membrane liquid;

[0037] S5, adjusting the membrane liquid temperature to 25°C and the pH value to 7, adding 10 parts of glutaraldehyde for cross-linking reaction;

[0038] S6. The mixed materials are fed into an extruder and extruded into a ground film shape through a die; during extrusion, the heating device is controlled to 50° C. to solidify the ground film into shape.

[0039] Example 2

[0040] S1. Pour 75 parts of starch wastewater into a round-bottom flask equipped with a stirrer, stir at a speed of 300 r / min for 30 min at a temperature of 80°C, and then concentrate to 0.7 times to obtain concentrated starch water; add 30 parts of glycerol to the concentrated starch water to prepare a slurry, and then stir and gelatinize at 60°C to obtain a starch gelatinization slurry;

[0041] S2, heating 30 parts of bamboo fibers at 55° C. for 4 hours to remove moisture, and then ball milling at 550 rpm / min for 5 hours to obtain bamboo fiber powder with a particle size of 100 nm;

[0042] S3, starch gelatinization slurry is mixed with bamboo fiber powder, 18 parts of polyvinyl alcohol and 10 parts of calcium carbonate are added in sequence and stirred to obtain a membrane liquid;

[0043] S4, degassing the membrane liquid under vacuum conditions to remove bubbles in the membrane liquid;

[0044] S5, adjusting the membrane liquid temperature to 25°C and the pH value to 7, adding 8 parts of glutaraldehyde for cross-linking reaction;

[0045] S6. The mixed materials are fed into an extruder and extruded into a mulch film shape through a die; during extrusion, the heating device is controlled to 50°C to solidify the mulch film into shape.

[0046] The difference between Example 2 and Example 1 is that the raw material components are different, but both are within the protection scope of the present invention.

[0047] Example 3

[0048] S1. Pour 90 parts of starch wastewater into a round-bottom flask equipped with a stirrer, stir at a speed of 300 r / min for 30 min at a temperature of 80°C, and then concentrate to 0.7 times to obtain concentrated starch water; add 18 parts of glycerol to the concentrated starch water to prepare a slurry, and then stir and gelatinize at 60°C to obtain a starch gelatinization slurry;

[0049] S2, heating 20 parts of bamboo fibers at 55° C. for 4 hours to remove moisture, and then ball milling at 550 rpm / min for 5 hours to obtain bamboo fiber powder with a particle size of 100 nm;

[0050] S3, starch gelatinization slurry is mixed with bamboo fiber powder, 10 parts of polyvinyl alcohol and 5 parts of calcium carbonate are added in sequence and stirred to obtain a membrane liquid;

[0051] S4, degassing the membrane liquid under vacuum conditions to remove bubbles in the membrane liquid;

[0052] S5, adjusting the membrane liquid temperature to 25°C and the pH value to 7, adding 15 parts of glutaraldehyde for cross-linking reaction;

[0053] S6. The mixed materials are fed into an extruder and extruded into a mulch film shape through a die; during extrusion, the heating device is controlled to 50°C to solidify the mulch film into shape.

[0054] The difference between Example 3 and Example 1 is that the raw material components are different, but both are within the protection scope of the present invention.

[0055] In order to verify the superiority of the raw materials, proportions and methods of the present invention, comparative examples - comparative examples 5 are set here with Example 1 as a comparison.

[0056] Comparative Example 1

[0057] S1. Pour 80 parts of starch wastewater into a round-bottom flask equipped with a stirrer, stir at 80°C and 300 r / min for 30 min, and then concentrate to 0.7 times to obtain concentrated starch water; then stir and gelatinize at 60°C to obtain starch gelatinization slurry;

[0058] S2, heating 25 parts of bamboo fibers at 55° C. for 4 hours to remove moisture, and then ball milling at 550 rpm / min for 5 hours to obtain bamboo fiber powder with a particle size of 100 nm;

[0059] S3, starch gelatinization slurry is mixed with bamboo fiber powder, 14 parts of polyvinyl alcohol and 8 parts of calcium carbonate are added in sequence and stirred to obtain a membrane liquid;

[0060] S4, degassing the membrane liquid under vacuum conditions to remove bubbles in the membrane liquid;

[0061] S5, adjusting the membrane liquid temperature to 25°C and the pH value to 7, adding 10 parts of glutaraldehyde for cross-linking reaction;

[0062] S6. The mixed materials are fed into an extruder and extruded into a ground film shape through a die; during extrusion, the heating device is controlled to 50° C. to solidify the ground film into shape.

[0063] The difference between Comparative Example 1 and Example 1 is that no glycerol is added.

[0064] Comparative Example 2

[0065] S1. Pour 80 parts of starch wastewater into a round-bottom flask equipped with a stirrer, stir at a speed of 300 r / min for 30 min at a temperature of 80°C, and then concentrate to 0.7 times to obtain concentrated starch water; add 22 parts of glycerol to the concentrated starch water to prepare a slurry, and then stir and gelatinize at 60°C to obtain a starch gelatinization slurry;

[0066] S2, adding 14 parts of polyvinyl alcohol and 8 parts of calcium carbonate to the starch gelatinized slurry and stirring to obtain a membrane liquid;

[0067] S3, degassing the membrane liquid under vacuum conditions to remove bubbles in the membrane liquid;

[0068] S4, adjusting the membrane liquid temperature to 25°C and the pH value to 7, adding 10 parts of glutaraldehyde for cross-linking reaction;

[0069] S5. The mixed materials are fed into an extruder and extruded into a ground film shape through a die; during extrusion, the heating device is controlled to 50° C. to solidify the ground film into shape.

[0070] The difference between Comparative Example 2 and Example 1 is that bamboo fiber is not added.

[0071] Comparative Example 3

[0072] S1. Pour 80 parts of starch wastewater into a round-bottom flask equipped with a stirrer, stir at a speed of 300 r / min for 30 min at a temperature of 80°C, and then concentrate to 0.7 times to obtain concentrated starch water; add 22 parts of glycerol to the concentrated starch water to prepare a slurry, and then stir and gelatinize at 60°C to obtain a starch gelatinization slurry;

[0073] S2, grinding 25 parts of bamboo fibers into bamboo fiber powder;

[0074] S3, starch gelatinization slurry is mixed with bamboo fiber powder, 14 parts of polyvinyl alcohol and 8 parts of calcium carbonate are added in sequence and stirred to obtain a membrane liquid;

[0075] S4, degassing the membrane liquid under vacuum conditions to remove bubbles in the membrane liquid;

[0076] S5, adjusting the membrane liquid temperature to 25°C and the pH value to 7, adding 10 parts of glutaraldehyde for cross-linking reaction;

[0077] S6. The mixed materials are fed into an extruder and extruded into a ground film shape through a die; during extrusion, the heating device is controlled to 50° C. to solidify the ground film into shape.

[0078] The difference between Comparative Example 3 and Example 1 is that the ball-milled bamboo fiber powder is replaced with ordinary bamboo fiber powder.

[0079] Comparative Example 4

[0080] S1. Pour 60 parts of starch wastewater into a round-bottom flask equipped with a stirrer, stir at a speed of 300 r / min for 30 min at a temperature of 80°C, and then concentrate to 0.7 times to obtain concentrated starch water; add 35 parts of glycerol to the concentrated starch water to prepare a slurry, and then stir and gelatinize at 60°C to obtain a starch gelatinization slurry;

[0081] S2, heating 10 parts of bamboo fibers at 55° C. for 4 hours to remove moisture, and then ball milling at 550 rpm / min for 5 hours to obtain bamboo fiber powder with a particle size of 100 nm;

[0082] S3, starch gelatinization slurry is mixed with bamboo fiber powder, 25 parts of polyvinyl alcohol and 15 parts of calcium carbonate are added in sequence and stirred to obtain a membrane liquid;

[0083] S4, degassing the membrane liquid under vacuum conditions to remove bubbles in the membrane liquid;

[0084] S5, adjusting the membrane liquid temperature to 25°C and the pH value to 7, adding 3 parts of glutaraldehyde for cross-linking reaction;

[0085] S6. The mixed materials are fed into an extruder and extruded into a ground film shape through a die; during extrusion, the heating device is controlled to 50° C. to solidify the ground film into shape.

[0086] The difference between Comparative Example 4 and Example 1 is that each raw material component is not within the protection scope of the present invention.

[0087] Comparative Example 5

[0088] S1, 80 parts of starch wastewater, 25 parts of bamboo fiber, 22 parts of glycerol, 14 parts of polyvinyl alcohol, 8 parts of calcium carbonate, and 10 parts of glutaraldehyde are added in sequence and mixed and stirred evenly;

[0089] S2 feeds the mixed materials into an extruder, extrude them into a mulch film shape through a die, and then dry them to solidify the mulch film.

[0090] The difference between Comparative Example 5 and Example 1 is that the preparation method of the present invention is not adopted.

[0091] The mulch films prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were tested, and the results are shown in Table 1:

[0092] Tensile strength(MPa) Elongation at break (%) Environmental safety Example 1 8.84 55.00 No secondary pollution to the environment Example 2 7.33 61.32 No secondary pollution to the environment Example 3 9.14 40.58 No secondary pollution to the environment Comparative Example 1 4.85 84.87 No secondary pollution to the environment Comparative Example 2 6.49 73.39 No secondary pollution to the environment Comparative Example 3 6.86 72.11 No secondary pollution to the environment Comparative Example 4 5.40 77.10 No secondary pollution to the environment Comparative Example 5 7.05 68.59 No secondary pollution to the environment

[0093] As shown in Table 1, the present invention limits the raw material composition of the degradable mulch film, takes starch wastewater as the basis, and adds ball-milled bamboo fiber to obtain a light and tough degradable starch film, thereby improving the mechanical properties of the degradable mulch film. Starch wastewater is used as the process water for bamboo fiber reinforced starch-based composite film. This process can not only offset the treatment cost of starch wastewater, but also ensure the safety of the product by producing composite film with starch wastewater, so as to provide new ideas for the resource utilization of starch wastewater.

[0094] The mulch films prepared in Examples 1 to 3 of the present invention have high tensile strength and elongation at break, and can meet the requirements for mulch film strength in agricultural production; by modifying starch and adding additives, the mulch films have good waterproof properties and can effectively prevent soil moisture evaporation; at the same time, by adding bamboo fiber and other natural ingredients, the mulch films have certain insect and pest control effects, can reduce the use of pesticides, and protect soil health; in actual application tests, compared with plastic mulch films, crops covered with degradable mulch films grow more robustly and have significantly improved yields.

[0095] By comparing the embodiment with comparative examples 2 and 3, it can be seen that the addition of bamboo fiber can also reduce the addition of other chemical additives, reduce production costs, and significantly reduce the weight of the mulch film; the addition of ball-milled bamboo fiber can effectively improve the mechanical properties of the prepared starch film to meet production requirements. Other mulch films that do not adopt the preparation method of the present invention or whose raw material components are not within the scope of the present invention have poor effects.

[0096] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A degradable mulch film made of starch wastewater and bamboo fiber, characterized by: In terms of weight, the ground film comprises 75-90 parts of starch wastewater, 20-30 parts of bamboo fiber, 10-18 parts of polyvinyl alcohol, 18-30 parts of glycerol, 8-15 parts of cross-linking agent and 5-10 parts of filler.

2. The degradable mulch film made of starch wastewater and bamboo fiber according to claim 1, characterized in that: The starch wastewater is at least one of potato starch wastewater, wheat starch wastewater, sweet potato starch wastewater, lotus root starch wastewater, corn starch wastewater, rice starch wastewater and pea starch wastewater.

3. The degradable mulch film made of starch wastewater and bamboo fiber according to claim 1, characterized in that: The cross-linking agent is glutaraldehyde, the filler is calcium carbonate, and the particle size of the bamboo fiber is 80-120 nm.

4. A degradable mulch film made of bamboo fiber composited with starch wastewater according to any one of claims 1 to 3, further comprising a method for preparing the degradable mulch film made of bamboo fiber composited with starch wastewater, characterized in that: The following steps are included: S1, preliminarily treating starch wastewater and concentrating it to obtain concentrated starch water; adding glycerol to the concentrated starch water to prepare a slurry, and then stirring and gelatinizing under heating conditions to obtain a starch gelatinized slurry; S2, ball-milling the bamboo fiber to obtain ball-milled bamboo fiber powder; S3, starch gelatinization slurry is mixed with bamboo fiber powder, polyvinyl alcohol and filler are added in sequence and stirred to obtain membrane liquid; S4, degassing the membrane liquid under vacuum conditions to remove bubbles in the membrane liquid; S5, adjusting the temperature and pH value of the membrane solution, and adding a cross-linking agent to carry out a cross-linking reaction; S6. The mixed materials are fed into an extruder and extruded into a ground film shape through a die; during extrusion, a heating device is used to solidify the ground film into shape.

5. The method for preparing a degradable mulch film by combining starch wastewater with bamboo fiber according to claim 4, characterized in that: In the step S1, the starch wastewater is treated by flotation separation, the starch wastewater is poured into a round-bottom flask equipped with a stirrer, and stirred at a temperature of 70-90° C. and a rotation speed of 200-400 r / min for 25-45 min.

6. The method for preparing a degradable mulch film by combining starch wastewater with bamboo fiber according to claim 4, characterized in that: In S2, the ball milling method is: the bamboo fiber is heated at 50-60°C for 3-5 hours to remove moisture, and the heated bamboo fiber is ball milled at a speed of 400-700rp / min using zirconium oxide ball milling beads. The ball milling time is 3-12 hours, and the mass ratio of bamboo fiber to zirconium oxide ball milling beads is 1:

10.

7. The method for preparing a degradable mulch film by combining starch wastewater with bamboo fiber according to claim 4, characterized in that: In step S3, the membrane liquid is degassed under a vacuum condition of 0.01 MPa for 15-20 minutes.

8. The method for preparing a degradable mulch film by combining starch wastewater with bamboo fiber according to claim 4, characterized in that: In step S5, the temperature of the membrane liquid is 20-30° C., and the pH value is 4.5-9.

5.

9. The method for preparing a degradable mulch film by combining starch wastewater with bamboo fiber according to claim 4, characterized in that: In step S6, the temperature of the heating device during extrusion is 45-55°C.

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