Method for preparing environment-friendly plate without adhesive by microbial conversion of bamboo fiber

Abstract

The present application relates to the technical field of artificial board, and particularly relates to a method for preparing a no-glue adhesion environment-friendly board by microbial conversion of forest bamboo fibers, comprising the following steps: S1: forest bamboo fiber powder, marine arthropod dry shell and HEBES / BuLi mixture are ultrasonically oscillated and stirred in a butanol-water solution, and wet fibers are obtained by pressure filtration; S2: after the wet fibers are sterilized, hot Clostridium thermocellum-Clostridium thermohydrosulfuricum complex bacteria fermentation and complex enzyme preparation enzymolysis are added, and no inorganic powder, calcium stearate and trimethylchlorosilane are reacted, and fiber-inorganic compound wet powder is obtained by pressure filtration; S3: the compound wet powder is ball milled and dried to obtain modified compound powder; S4: the modified compound powder is mixed with thermoplastic resin, lubricant and hygroscopic master batch to perform intensive mixing and granulation; and S5: the no-glue adhesion environment-friendly board is obtained by extrusion molding. The present application can solve the problems of formaldehyde release of artificial board and poor compatibility of fibers and polyolefins in the prior art, and can realize no formaldehyde glue bonding and improve the mechanical properties, water resistance and mildew resistance of the board.

Description

Technical Field

[0001] This invention relates to the field of engineered wood products technology, and in particular to a method for preparing adhesive-free, environmentally friendly engineered wood products by microbial transformation of bamboo fibers. Background Technology

[0002] my country is the world's largest producer and consumer of engineered wood products. Traditional engineered wood products mainly use urea-formaldehyde resin, phenolic resin, and isocyanate as adhesives. These adhesives continuously release harmful substances such as formaldehyde during use, posing carcinogenic and cancer-promoting risks and seriously threatening human health and environmental safety. With increasingly stringent environmental regulations, the maximum limit for formaldehyde emissions from engineered wood products has been raised from E0 to ENF, creating an urgent need for formaldehyde-free adhesives. However, my country's weak foundation in the production and research and development of formaldehyde-free adhesives has become a key bottleneck restricting the high-quality development of the industry.

[0003] In the formaldehyde-free adhesive technology route, thermoplastic resins such as polyethylene and polypropylene have attracted attention due to their good adhesion and hydrophobicity. However, the large difference in surface polarity between polyolefins and bamboo fibers results in poor interfacial compatibility, making it difficult to obtain satisfactory mechanical properties and water resistance through direct composite. Therefore, systematic hydrophobication and ultrafine pretreatment of bamboo fibers is necessary. Furthermore, although lignin in wood fibers possesses natural adhesive properties, it is bonded to cellulose and hemicellulose to form a dense structure, restricting molecular mobility and hindering the full realization of its natural adhesive properties. While existing technologies include pretreatment methods such as high-pressure explosion, cooking, chemical treatment, or single enzymatic hydrolysis, these generally suffer from low treatment efficiency, insufficient lignin depolymerization, and weak interfacial bonding between fibers and resins, making it difficult to meet the requirements of industrial production.

[0004] Marine arthropod wastes such as crab shells and shrimp shells are rich in chitin and calcium carbonate, which have the potential for resource utilization. However, chitin is insoluble in water, dilute acids, dilute alkalis and conventional organic solvents, and it is tightly bound to calcium carbonate, making it difficult to effectively separate and activate. This greatly limits its high-value application in the field of composite materials. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing adhesive-free and environmentally friendly boards by microbial transformation of bamboo fiber, so as to solve the technical problems mentioned in the background art. To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing adhesive-free, environmentally friendly boards by microbial transformation of bamboo fibers includes the following steps: S1: Take fresh bamboo fiber powder, dried marine arthropod shells, and a mixture of 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium, and place them in a butanol-water solution. Under ultrasonic conditions with a frequency of 20-40 kHz and a power of 150-400 W, the mixture is shaken for 60-90 min. Then, the temperature is raised to 60℃, and 10-15 g of sodium dodecylbenzenesulfonate is added. The mixture is stirred continuously at a speed of 250 r / min for 24-96 h. After the treatment, the mixture is filtered, the filter residue is collected and washed to obtain wet fiber.

[0006] S2: The wet fiber was autoclaved at 120℃ for 10 min; after sterilization, it was cooled to 60-65℃, and then adjusted to a paste-like system with a water content of 50-75% using sterilized deionized water. Then, a complex of *Clostridium thermophilum* and *Clostridium thermophilum* was added and stirred for fermentation for 24 h. After fermentation, it was cooled to 30℃, and a complex enzyme preparation was added and stirred for another 36 h to obtain bamboo fiber. Inorganic powder was added to the bamboo fiber, the temperature was raised to 80℃, and then calcium stearate was added sequentially for 30 min and trimethylchlorosilane for 30 min. After the reaction, it was cooled to room temperature and filtered to obtain fiber-inorganic composite wet powder. S3: Take the fiber-inorganic composite wet powder and put it into a high-speed ball mill, add grinding aid, grind for 20~60 h, dry after grinding to obtain modified composite powder; S4: Thermoplastic resin, modified composite powder, lubricant and moisture-absorbing masterbatch are placed in a mixer-granulator and sealed and sheared at 150°C for 60 min to obtain primary blend masterbatch; S5: The primary blending masterbatch is fed into a sheet forming machine equipped with a screw extruder for blending and extrusion to obtain an adhesive-free environmentally friendly sheet.

[0007] Furthermore, in S1, the weight ratio of fresh bamboo fiber powder, dried marine arthropod shells, 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture, and butanol-water solution is 20:8:(2~3):60.

[0008] Further, in S1, the fresh bamboo fiber powder is a mixture of freshly cut and crushed eucalyptus and bamboo powder, with a particle size of 120 mesh and a moisture content of 50-60%; the dried shells of marine arthropods are a mixture of one or more of crab shells, shrimp shells, and horseshoe crab shells after crushing, with a particle size of 600 mesh; the 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture is prepared by mixing 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate and butyllithium in a weight ratio of (4-9):1; in the butanol-water solution, the volume ratio of butanol to water is 3:5.

[0009] Furthermore, in S2, the weight ratio of wet fiber, inorganic powder, Clostridium thermophilum-Clostridium thermophilum complex, complex enzyme preparation, calcium stearate, and trimethylchlorosilane is 80:150:1:2:1.5:1.5.

[0010] Furthermore, in S2, the inorganic powder is 500-mesh kaolinite-rich spherical clay; Furthermore, the *Clostridium thermophilum*-*Clostridium thermosulfide* complex is composed of *Clostridium thermophilum* and *Clostridium thermosulfide* mixed in a weight ratio of (4~5):1; the complex enzyme preparation is composed of chitinase, ferulic acid esterase, and laccase mixed in a weight ratio of 1:1:3.

[0011] Furthermore, in S3, the weight ratio of fiber-inorganic composite wet powder to grinding aid is 10:1; the grinding aid is low molecular weight sodium lignosulfonate with a number average molecular weight of 3000~4000.

[0012] Furthermore, in S3, the ball milling conditions are: 800 r / min, forward rotation for 30 min, pause for 5 min, reverse rotation for 30 min, and cycle; the weight ratio of grinding balls to grinding material is 2:8, wherein the diameter of the large grinding ball is 2 mm, the diameter of the small grinding ball is 0.2 mm, and the weight ratio of the large grinding ball to the small grinding ball is 1:7.

[0013] Furthermore, in S4, the weight ratio of thermoplastic resin, modified composite powder, lubricant and moisture-absorbing masterbatch is 25:75:2.5:2.5.

[0014] Furthermore, in S4, the thermoplastic resin is a virgin polyethylene or polypropylene with a melt index range of 0.5~3 g / 10min, and a recycled linear low-density polyethylene composite with a melt index range of 4~8 g / 10min, with a weight ratio of 4:1; the lubricant is homopolymer low molecular weight polyethylene wax; and the moisture-absorbing masterbatch is calcium oxide-PE masterbatch.

[0015] The advantages of this invention compared to the prior art are as follows: 1. This invention uses thermoplastic resin and depolymerized lignin as adhesives to replace traditional formaldehyde-containing adhesives, and employs ultrasonic-solvent impregnation and microbial enzymatic hydrolysis pretreatment to remove low-volatile substances from fibers, thereby avoiding formaldehyde release and reducing TVOC emissions, thus preparing environmentally friendly formaldehyde-free boards.

[0016] 2. This invention uses a complex of *Clostridium thermocellulose* and *Clostridium thermosulfide* bacteria with chitinase, ferulic acid esterase, and laccase as a complex enzyme preparation for multi-stage biodepolymerization. This process can dissociate the densely bound state of lignin, hemicellulose, and cellulose and reduce the molecular weight of lignin, thereby releasing the natural adhesive properties of lignin and improving its synergistic bonding effect with thermoplastic resins.

[0017] 3. This invention modifies fiber-inorganic materials by reacting calcium stearate with trimethylchlorosilane in sequence to achieve hydrophobicity, and then combines this with high-speed ball milling to obtain modified composite powder with a narrow particle size distribution. This improves the interfacial compatibility between bamboo fiber and polyolefin resin, thereby enhancing the water resistance and mechanical properties of the board.

[0018] 4. This invention uses 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium and butanol-water solution to pre-treat the dried shells of marine arthropods by swelling. Combined with chitinase hydrolysis and ball milling, it can depolymerize chitin and make its morphology regular, thereby giving the board anti-mildew properties. At the same time, the natural hydrophobicity of chitin and calcium carbonate is used to reduce the amount of modifier used.

[0019] 5. This invention obtains modified composite powder with a particle size distribution (d90-d10) / d50≤2.5 by strictly controlling ball milling conditions, which enables inorganic fillers to be uniformly dispersed in thermoplastic resin, thereby increasing the maximum filler fraction and reducing raw material production costs.

[0020] 6. This invention uses low molecular weight sodium lignosulfonate as a grinding aid, which can improve ball milling efficiency and powder dispersibility. At the same time, the aromatic rings and sulfonic acid groups it contains can participate in the hot pressing process, thereby playing the role of a binding aid and improving the quality of the board forming. Attached Figure Description

[0021] Figure 1 These are scanning electron microscope (SEM) images of the eucalyptus-Bamboo powder mixture and bamboo fiber of the present invention; wherein, A is a scanning electron microscope image of the eucalyptus-Bamboo powder mixture; and B is a scanning electron microscope image of the bamboo fiber obtained after S2 treatment. Figure 2 This is a product image of the adhesive-free environmentally friendly board prepared according to Example 1 of the present invention; Figure 3 This is a cross-sectional view of the plate material in Embodiment 1 of the present invention; Figure 4 This is a scanning electron microscope image of the cross-section of the plate material in Embodiment 1 of the present invention; Figure 5 These are scanning electron microscope (SEM) images of the plates from Embodiment 1 and Comparative Example 3 of the present invention after an anti-mildew test; wherein, A is the SEM image of Embodiment 1; and B is the SEM image of Comparative Example 3. Figure 6 This is a chromatogram of the VOC components released from the board material in Embodiment 1 of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the present invention will be further described in detail below with reference to preferred embodiments. However, it should be noted that many details listed in the specification are merely to provide the reader with a thorough understanding of one or more aspects of the invention, and these aspects of the invention can be achieved even without these specific details.

[0023] A method for preparing adhesive-free, environmentally friendly boards by microbial transformation of bamboo fibers includes the following steps: S1: Take fresh bamboo fiber powder, dried marine arthropod shells, and a mixture of 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium, and place them in a butanol-water solution. Under ultrasonic conditions with a frequency of 20-40 kHz and a power of 150-400 W, the mixture is shaken for 60-90 min. Then, the temperature is raised to 60℃, and 10-15 g of sodium dodecylbenzenesulfonate is added. The mixture is stirred continuously at a speed of 250 r / min for 24-96 h. After the treatment, the mixture is filtered, the filter residue is collected and washed to obtain wet fiber.

[0024] S2: The wet fiber was autoclaved at 120℃ for 10 min; after sterilization, it was cooled to 60-65℃, and then adjusted to a paste-like system with a water content of 50-75% using sterilized deionized water. Then, a complex of *Clostridium thermophilum* and *Clostridium thermophilum* was added and stirred for fermentation for 24 h. After fermentation, it was cooled to 30℃, and a complex enzyme preparation was added and stirred for another 36 h to obtain bamboo fiber. Inorganic powder was added to the bamboo fiber, the temperature was raised to 80℃, and then calcium stearate was added sequentially for 30 min and trimethylchlorosilane for 30 min. After the reaction, it was cooled to room temperature and filtered to obtain fiber-inorganic composite wet powder. S3: Take the fiber-inorganic composite wet powder and put it into a high-speed ball mill, add grinding aid, grind for 20~60 h, dry after grinding to obtain modified composite powder; S4: Thermoplastic resin, modified composite powder, lubricant and moisture-absorbing masterbatch are placed in a mixer-granulator and sealed and sheared at 150°C for 60 min to obtain primary blend masterbatch; S5: The primary blending masterbatch is fed into a sheet forming machine equipped with a screw extruder for blending and extrusion to obtain an adhesive-free environmentally friendly sheet.

[0025] In S1, the weight ratio of fresh bamboo fiber powder, dried marine arthropod shells, 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture, and butanol-water solution is 20:8:(2~3):60.

[0026] In S1, the fresh bamboo fiber powder is a mixture of freshly cut and crushed eucalyptus and bamboo powder, with a particle size of 120 mesh and a moisture content of 50-60%; the dried shells of marine arthropods are a mixture of one or more of crab shells, shrimp shells, and horseshoe crab shells, crushed, with a particle size of 600 mesh; the 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture is prepared by mixing 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate and butyllithium in a weight ratio of (4-9):1; in the butanol-water solution, the volume ratio of butanol to water is 3:5.

[0027] In S2, the weight ratio of wet fiber, inorganic powder, Clostridium thermophilum-Clostridium thermophilum complex, complex enzyme preparation, calcium stearate, and trimethylchlorosilane is 80:150:1:2:1.5:1.5.

[0028] In S2, the inorganic powder is 500-mesh kaolinite-rich spherical clay; The thermocrystal-thermosulfuric acid clostridium complex is composed of thermocrystal and thermosulfuric acid clostridium in a weight ratio of (4~5):1; the complex enzyme preparation is composed of chitinase, ferulic acid esterase and laccase in a weight ratio of 1:1:3.

[0029] In S3, the weight ratio of fiber-inorganic composite wet powder to grinding aid is 10:1; the grinding aid is low molecular weight sodium lignosulfonate with a number average molecular weight of 3000~4000.

[0030] In S3, the ball milling conditions are: 800 r / min, forward rotation for 30 min, pause for 5 min, reverse rotation for 30 min, and cycle; the weight ratio of grinding balls to grinding material is 2:8, where the diameter of the large grinding ball is 2 mm, the diameter of the small grinding ball is 0.2 mm, and the weight ratio of the large grinding ball to the small grinding ball is 1:7.

[0031] In S4, the weight ratio of thermoplastic resin, modified composite powder, lubricant and moisture-absorbing masterbatch is 25:75:2.5:2.5.

[0032] In S4, the thermoplastic resin is a virgin polyethylene or polypropylene with a melt index range of 0.5~3 g / 10min, and a recycled linear low-density polyethylene composite with a melt index range of 4~8 g / 10min, with a weight ratio of 4:1; the lubricant is homopolymer low molecular weight polyethylene wax with a weight average molecular weight of 1500~2000; the moisture-absorbing masterbatch is calcium oxide-PE masterbatch with a calcium oxide content greater than 90wt%.

[0033] The following description uses more specific examples.

[0034] Example 1 A method for preparing adhesive-free environmentally friendly boards by microbial conversion of bamboo fibers includes the following steps: S1: Take 2.0 kg of freshly cut and crushed eucalyptus-bamboo powder mixture with a moisture content of 50% and a mesh size of 120, 800 g of crab shell powder with a mesh size of 600, and 300 g of 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture prepared by mixing 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate and butyllithium in a weight ratio of 5:1. Place them in 6 kg of butanol-water solution with a volume ratio of 3:5 and treat with ultrasonic vibration at a frequency of 25 kHz and a power of 250 W for 75 min. Then raise the temperature to 60 °C, add 12 g of sodium dodecylbenzenesulfonate, and continue stirring at a speed of 250 r / min for 72 h. After treatment, filter, collect the filter residue and wash it with water to obtain wet fiber with a moisture content of 18 wt%. S2: Place 2.0 kg of wet fiber into an autoclave and autoclave at 120°C for 10 min. After sterilization, reduce the temperature to 63°C and adjust the mixture to a paste-like system with a water content of 70% using sterilized deionized water. Then add 25 g of a compound bacteria consisting of Clostridium thermophilum and Clostridium thermosulfide in a weight ratio of 4:1 and stir to ferment for 24 h. After fermentation, cool to 30°C and add 50 g of a compound enzyme preparation consisting of chitinase, ferulic acid esterase, and laccase in a weight ratio of 1:1:3. Continue stirring for 36 h to obtain bamboo fiber with a number-average molecular weight of lignin of 2458 and a molecular weight distribution coefficient (PDI) of 2.43. The microstructure of bamboo fiber and eucalyptus-Bamboo powder mixture was observed and compared using scanning electron microscopy. The results are as follows: Figure 1 As shown in Figure AB.

[0035] from Figure 1 As can be seen from A, the fresh powder appears as robust strips or bundles, with smooth fiber surfaces, rigid shapes, and retains the dense vascular bundle structure of the original plant tissue. The fiber bundles are tightly bound together, resulting in a relatively small specific surface area. From Figure 1 As can be seen from B in the figure, after fermentation and enzymatic hydrolysis by S2 compound bacteria, the fibers are significantly refined and split into filaments. The coarse fiber bundles are dissociated into a large number of fine and long microfibers, the surface roughness is significantly increased, and a fluffy net-like interwoven morphology is presented, with a significant increase in specific surface area. Add 3.75 kg of 500-mesh kaolinite-rich ball clay to bamboo fiber, heat to 80℃, add 37.5 g of calcium stearate and react for 30 min, then add 37.5 g of trimethylchlorosilane and react for 30 min, cool to room temperature, filter by pressure, and obtain hydrophobically modified fiber-inorganic composite wet powder with a water content of 14.5 wt%. S3: Take 3.0 kg of fiber-inorganic composite wet powder and put it into a high-speed ball mill. Add 600 g of sodium lignosulfonate with a number average molecular weight of 3200 as a grinding aid. Grind for 50 h under the following conditions: 800 rpm, forward rotation for 30 minutes, pause for 5 minutes, reverse rotation for 30 minutes. The weight ratio of grinding balls to grinding material is 2:8. The diameter of the large grinding balls is 2 mm, the diameter of the small grinding balls is 0.2 mm, and the weight ratio of the large grinding balls to the small grinding balls is 1:7. After grinding, dry the discharged material to obtain a modified composite powder with a particle size distribution (d90-d10) / d50 of 2.12. S4: Place 800g of new polyethylene with a melt index of 1.8 g / 10min, 200g of recycled linear low-density polyethylene with a melt index of 5.0g / 10min, 3.0kg of modified composite powder, 100g of homopolymer low molecular weight polyethylene wax and 100g of calcium oxide-PE masterbatch into a mixer-granulator and seal and shear at 150℃ for 60 min to obtain primary blend masterbatch; S5: The primary blending masterbatch is transferred to a sheet forming machine equipped with a screw extruder for blending and extrusion to obtain, as shown in the figure below. Figure 2 The image shows an environmentally friendly board material that requires no adhesive bonding.

[0036] The plate prepared in this embodiment was subjected to low-temperature brittle fracture in liquid nitrogen, resulting in the following: Figure 3 The cross-section shown; cross-sectional scanning electron microscopy observation and analysis were performed, and the results are as follows. Figure 4 As shown.

[0037] from Figure 4 As can be seen, the cross-section exhibits a dense three-dimensional interwoven fiber network, with the fiber surface uniformly coated by resin. The interface is blurred and there is no debonding phenomenon, indicating that the hydrophobic modification significantly improves the interfacial compatibility between the fiber and the polyolefin. The inorganic filler is uniformly dispersed, with no obvious agglomeration observed. The cross-section exhibits ductile fracture characteristics with uneven surfaces, and fiber pull-out is visible, indicating that the fibers effectively bear and dissipate energy. The porosity is low and uniformly distributed.

[0038] Example 2 A method for preparing adhesive-free environmentally friendly boards by microbial conversion of bamboo fibers includes the following steps: S1: Take 2.0 kg of freshly cut and crushed eucalyptus-bamboo powder mixture with a moisture content of 50% and a mesh size of 120, 800 g of horseshoe crab shell powder with a mesh size of 600, and 200 g of 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture prepared by mixing 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate and butyllithium in a weight ratio of 9:1. Place them in 6 kg of butanol-water solution with a volume ratio of 3:5 and treat with ultrasonic vibration at a frequency of 20 kHz and a power of 200 W for 60 min. Then raise the temperature to 60 °C, add 10 g of sodium dodecylbenzenesulfonate, and continue stirring at a speed of 250 r / min for 32 h. After treatment, filter, collect the filter residue and wash it with water to obtain wet fiber with a moisture content of 25 wt%. S2: Place 2.0 kg of wet fiber into an autoclave and autoclave at 120℃ for 10 min. After sterilization, reduce the temperature to 60℃ and adjust the mixture to a paste-like system with a water content of 50% using sterilized deionized water. Then add 25 g of a *Clostridium thermophilum*-*Clostridium thermophilum* complex, which is a mixture of *Clostridium thermophilum* and *Clostridium thermophilum* in a weight ratio of 4:1. Stir and ferment for 24 h. After fermentation, cool to 30℃ and add 50 g of a complex enzyme preparation, which is a mixture of chitinase, ferulic acid esterase, and laccase in a weight ratio of 1:1:3. Continue stirring for 36 h to obtain bamboo fiber with a lignin number-average molecular weight of 3560 and a molecular weight distribution coefficient (PDI) of 3.3. Add 3.75 kg of [unclear text - possibly a specific type of bacteria] to the bamboo fiber. 500-mesh kaolinite-rich ball clay was heated to 80℃, and 37.5g of calcium stearate was added and reacted for 30min. Then, 37.5g of trimethylchlorosilane was added and reacted for 30min. After cooling to room temperature, the mixture was filtered to obtain hydrophobically modified fiber-inorganic composite wet powder with a water content of 18wt%. S3: Take 3.0 kg of fiber-inorganic composite wet powder and put it into a high-speed ball mill. Add 600 g of sodium lignosulfonate with a number average molecular weight of 3200 as a grinding aid. Grind for 24 hours under the following cycle: 800 rpm, forward rotation for 30 minutes, pause for 5 minutes, reverse rotation for 30 minutes. The weight ratio of grinding balls to grinding material is 2:8. The diameter of the large grinding balls is 2 mm, and the diameter of the small grinding balls is 0.2 mm. The weight ratio of the large grinding balls to the small grinding balls is 1:7. After grinding, dry the discharged material to obtain a modified composite powder with a particle size distribution (d90-d10) / d50 of 2.45. S4: Place 800g of new polyethylene with a melt index of 2.5g / 10min, 200g of recycled linear low-density polyethylene with a melt index of 8.0g / 10min, 3.0kg of modified composite powder, 100g of homopolymer low molecular weight polyethylene wax and 100g of calcium oxide-PE masterbatch into a mixer-granulator and seal and shear at 150℃ for 60 min to obtain primary blend masterbatch; S5: The primary blending masterbatch is transferred to a sheet forming machine with a screw extruder for blending and extrusion to obtain an adhesive-free environmentally friendly sheet.

[0039] Example 3 A method for preparing adhesive-free environmentally friendly boards by microbial conversion of bamboo fibers includes the following steps: S1: Take 2.0 kg of freshly cut and crushed eucalyptus-bamboo powder mixture with a moisture content of 50% and a mesh size of 120, 800 g of shrimp shell powder with a mesh size of 600, and 300 g of 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture prepared by mixing 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate and butyllithium in a weight ratio of 4:1. Place them in 6 kg of butanol-water solution with a volume ratio of 3:5 and treat with ultrasonic vibration at a frequency of 40 kHz and a power of 400 W for 90 min. Then raise the temperature to 60 °C, add 15 g of sodium dodecylbenzenesulfonate, and continue stirring at a speed of 250 r / min for 96 h. After treatment, filter, collect the filter residue and wash it with water to obtain wet fiber with a moisture content of 16 wt%. S2: Place 2.0 kg of wet fiber into an autoclave and autoclave at 120℃ for 10 min. After sterilization, reduce the temperature to 65℃ and adjust the mixture to a paste-like system with a water content of 70% using sterilized deionized water. Then add 25 g of a *Clostridium thermophilum*-*Clostridium thermophilum* complex, which is a mixture of *Clostridium thermophilum* and *Clostridium thermophilum* in a weight ratio of 5:1. Stir and ferment for 24 h. After fermentation, cool to 30℃ and add 50 g of a complex enzyme preparation, which is a mixture of chitinase, ferulic acid esterase, and laccase in a weight ratio of 1:1:3. Continue stirring for 36 h to obtain bamboo fiber with a lignin number-average molecular weight of 2300 and a molecular weight distribution coefficient (PDI) of 2.05. Add 3.75 kg of [unspecified ingredient] to the bamboo fiber. 500-mesh kaolinite-rich ball clay was heated to 80℃, and 37.5g of calcium stearate was added and reacted for 30min. Then, 37.5g of trimethylchlorosilane was added and reacted for 30min. After cooling to room temperature, the mixture was filtered to obtain hydrophobically modified fiber-inorganic composite wet powder with a water content of 13wt%. S3: Take 3.0 kg of fiber-inorganic composite wet powder and put it into a high-speed ball mill. Add 600 g of sodium lignosulfonate with a number average molecular weight of 3200 as a grinding aid. Grind for 60 hours under the following conditions: 800 rpm, forward rotation for 30 minutes, pause for 5 minutes, reverse rotation for 30 minutes. The weight ratio of grinding balls to grinding material is 2:8. The diameter of the large grinding balls is 2 mm, the diameter of the small grinding balls is 0.2 mm, and the weight ratio of the large grinding balls to the small grinding balls is 1:7. After grinding, dry the discharged material to obtain a modified composite powder with a particle size distribution (d90-d10) / d50 of 1.8. S4: Place 800g of new polyethylene with a melt index of 1.2g / 10min, 200g of recycled linear low-density polyethylene with a melt index of 6.0g / 10min, 3.0kg of modified composite powder, 100g of homopolymer low molecular weight polyethylene wax and 100g of calcium oxide-PE masterbatch into a mixer-granulator and seal and shear at 150℃ for 60 min to obtain primary blend masterbatch; S5: The primary blending masterbatch is transferred to a sheet forming machine with a screw extruder for blending and extrusion to obtain an adhesive-free environmentally friendly sheet.

[0040] Example 4 A method for preparing adhesive-free environmentally friendly boards by microbial conversion of bamboo fibers includes the following steps: S1: Take 2.0 kg of freshly cut and crushed eucalyptus-bamboo powder mixture with a moisture content of 50% and a mesh size of 120, 800 g of crab shell-horseshoe crab shell powder with a mesh size of 600, and 260 g of 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture prepared by mixing 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate and butyllithium in a weight ratio of 6:1. Place them in 6 kg of butanol-water solution with a volume ratio of 3:5 and treat with ultrasonic vibration at a frequency of 30 kHz and a power of 300 W for 85 min. Then raise the temperature to 60 °C, add 12 g of sodium dodecylbenzenesulfonate, and continue stirring at a speed of 250 r / min for 90 h. After treatment, filter, collect the filter residue and wash it with water to obtain wet fiber with a moisture content of 18 wt%. S2: Place 2.0 kg of wet fiber into an autoclave and autoclave at 120℃ for 10 min. After sterilization, reduce the temperature to 63℃ and adjust the mixture to a paste-like system with a water content of 70% using sterilized deionized water. Then add 25 g of a *Clostridium thermophilum*-*Clostridium thermophilum* complex, which is a mixture of *Clostridium thermophilum* and *Clostridium thermophilum* in a weight ratio of 4:1. Stir and ferment for 24 h. After fermentation, cool to 30℃ and add 50 g of a complex enzyme preparation, which is a mixture of chitinase, ferulic acid esterase, and laccase in a weight ratio of 1:1:3. Continue stirring for 36 h to obtain bamboo fiber with a lignin number-average molecular weight of 2387 and a molecular weight distribution coefficient (PDI) of 2.27. Add 3.75 kg of [unspecified ingredient] to the bamboo fiber. 500-mesh kaolinite-rich ball clay was heated to 80℃, and 37.5g of calcium stearate was added and reacted for 30min. Then, 37.5g of trimethylchlorosilane was added and reacted for 30min. After cooling to room temperature, the mixture was filtered to obtain hydrophobically modified fiber-inorganic composite wet powder with a water content of 15wt%. S3: Take 3.0 kg of fiber-inorganic composite wet powder and put it into a high-speed ball mill. Add 600 g of sodium lignosulfonate with a number average molecular weight of 3200 as a grinding aid. Grind for 55 hours under the following conditions: 800 rpm, forward rotation for 30 minutes, pause for 5 minutes, reverse rotation for 30 minutes. The weight ratio of grinding balls to grinding material is 2:8. The diameter of the large grinding balls is 2 mm, the diameter of the small grinding balls is 0.2 mm, and the weight ratio of the large grinding balls to the small grinding balls is 1:7. After grinding, dry the discharged material to obtain a modified composite powder with a particle size distribution (d90-d10) / d50 of 2.0. S4: Place 800g of new polyethylene with a melt index of 1.6g / 10min, 200g of recycled linear low-density polyethylene with a melt index of 5.5g / 10min, 3.0kg of modified composite powder, 100g of homopolymer low molecular weight polyethylene wax and 100g of calcium oxide-PE masterbatch into a mixer-granulator and seal and shear at 150℃ for 60 min to obtain primary blend masterbatch; S5: The primary blending masterbatch is transferred to a sheet forming machine with a screw extruder for blending and extrusion to obtain an adhesive-free environmentally friendly sheet.

[0041] Comparative Example 1 The process is basically the same as in Example 1, except that in S1, the eucalyptus-bamboo powder mixture is replaced with eucalyptus powder with the same moisture content and mesh size.

[0042] Comparative Example 2 It is basically the same as Example 1, except that in S1, no dried marine arthropod shells are added.

[0043] Comparative Example 3 The process is basically the same as in Example 1, except that in S1, the 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture was not added.

[0044] Comparative Example 4 The process is basically the same as in Example 1, except that in S2, the compound enzyme preparation is replaced with 30g of laccase.

[0045] Comparative Example 5 The process is basically the same as in Example 1, except that in S2, the kaolinite-rich spherical clay is replaced with heavy calcium carbonate.

[0046] Comparative Example 6 It is basically the same as Example 1, except that sodium lignosulfonate, a grinding aid, was not added in S3.

[0047] Performance testing 1. Water absorption performance test: The water absorption rate of the environmentally friendly boards prepared in Examples 1-4 and Comparative Examples 1-6 was tested according to EN 15534-1:2014. The results are shown in Table 1.

[0048] Table 1 Results of water absorption performance test As can be seen from Table 1, the water absorption rates of Examples 1 to 4 are 1.85%, 2.46%, 2.15%, and 2.26%, respectively. Among them, Example 1 has the lowest water absorption rate, which is significantly lower than that of Comparative Examples 1 to 6, indicating that this application can significantly reduce the water absorption performance of the board.

[0049] Comparative Example 1, which used eucalyptus powder, had a water absorption rate of 2.98%. Example 1, compared to Comparative Example 1, showed a 37% reduction in water absorption rate, indicating that introducing *Phyllostachys edulis* into bamboo fiber can significantly reduce the water absorption rate of the board. This is because the surface of *Phyllostachys edulis* fiber is rich in a natural silica layer, possessing natural hydrophobic properties. Furthermore, its high fiber aspect ratio and denser interwoven structure allow it to form more tortuous water penetration paths within the board, effectively hindering water absorption.

[0050] Comparative Example 2, which did not contain dried marine arthropod shells, had a water absorption rate of 2.17%. Example 1, compared to Comparative Example 2, showed a 14.7% reduction in water absorption rate, indicating that the introduction of dried marine arthropod shells had a synergistic effect in reducing water absorption. This is because the natural combination of chitin and calcium carbonate in the dried marine arthropod shells endows them with excellent natural hydrophobicity. Compared to organic matter, inorganic calcium carbonate is more likely to undergo hydrophobic reactions with calcium stearate and trimethylchlorosilane, allowing it to be uniformly dispersed in the resin matrix as a well-ordered hydrophobic filler, thereby reducing water absorption.

[0051] Comparative Example 3, which did not contain the 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture, had a water absorption rate of 3.42%. Compared to Comparative Example 3, Example 1 showed a 45.9% reduction in water absorption rate, indicating that this mixture is the core pretreatment agent for reducing the water absorption rate of the board. This is because the mixture can deeply swell the fibers and chitin in butanol-water solution and effectively remove residual low-volatility hydrophilic impurities from the fibers. At the same time, it helps to promote the modifier to perform preliminary hydrophobic modification on the fiber surface. Comparative Example 3 did not use this component, which resulted in a large amount of hydrophilic hydroxyl groups remaining on the fiber surface and incomplete removal of low-volatility substances. After molding, the porosity of the board increased, the capillary water absorption effect intensified, and the water absorption rate increased.

[0052] Comparative Example 4, using only laccase, had a water absorption rate of 3.38%. Example 1, compared to Comparative Example 4, showed a 54.7% reduction in water absorption rate, indicating that the synergistic effect of the compound enzyme preparation played a crucial role in reducing water absorption. The ferulic acid esterase in the compound enzyme preparation of this application can cleave the cross-linking bonds between lignin and polysaccharides, and the chitinase can decompose chitin. Together with laccase, they fully open the dense fiber structure, allowing the thermoplastic resin to fully impregnate and coat the fibers, reducing interfacial porosity. The synergistic effect of these three enzymes improves the waterproof performance of the board.

[0053] Comparative Example 5, in which kaolinite-rich ball clay was replaced with heavy calcium carbonate, had a water absorption rate of 2.24%. Compared to Comparative Example 5, Example 1 showed a 17.4% reduction in water absorption rate. This is because the kaolinite in the ball clay has a platy structure, which can form a denser physical packing in the board and extend the water penetration path. It also has better compatibility with fibers and resins, and a denser interfacial bond, thereby further reducing the water absorption rate.

[0054] Comparative Example 6, without the addition of grinding aid, had a water absorption rate of 2.20%. Example 1, compared to Comparative Example 6, showed a 15.9% reduction in water absorption rate, indicating that the addition of the grinding aid sodium lignosulfonate has a positive effect on reducing water absorption. The grinding aid of this application can improve ball milling efficiency, make the particle size distribution of the modified composite powder more uniform, and make the powder more evenly dispersed in the thermoplastic resin, thereby reducing the water penetration channels.

[0055] Based on the above water absorption data, it can be seen that this application can significantly reduce the water absorption of the board through multi-stage synergistic pretreatment of ultrasonic-chemical swelling, microbial fermentation, compound enzymatic hydrolysis, hydrophobic modification and ultrafine ball milling.

[0056] 2. Mechanical property testing: The environmentally friendly boards prepared in Examples 1-4 and Comparative Examples 1-6 were tested for static bending strength and flexural modulus of elasticity using ASTM D7031-11. The results are shown in Table 2.

[0057] Table 2 Mechanical Performance Test Results As can be seen from Table 2, the static bending strengths of Examples 1 to 4 are 34.0 MPa, 33.4 MPa, 35.1 MPa, and 34.3 MPa, respectively, and the flexural moduli are 1856 MPa, 1758 MPa, 1954 MPa, and 1904 MPa, respectively. Among them, Example 1 has a static bending strength of 35.1 MPa and a flexural modulus of 1954 MPa, which are the optimal levels.

[0058] Comparative Example 3, which did not contain the 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture, performed the worst, with a static bending strength of only 32.1 MPa and a flexural modulus of only 1542 MPa. Example 1 showed a 9.3% improvement in static bending strength and a 21.6% improvement in flexural modulus compared to Comparative Example 3. Comparative Example 4, which replaced the complex enzyme preparation with a single laccase, performed the second best, with a static bending strength of 32.6 MPa and a flexural modulus of 1621 MPa. Example 1 showed a 7.7% improvement in static bending strength and a 17% improvement in flexural modulus compared to Comparative Example 4. This indicates that chemical swelling pretreatment and multi-enzyme synergistic depolymerization are the core factors supporting the mechanical properties of the sheet material. This is because the mixture of 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium induces deep swelling of the fiber and chitin dry shell in the butanol-water system, providing a physical penetration channel for the subsequent invasion of the Clostridium thermophilum-Clostridium thermosulfide complex and the action of the complex enzyme preparation; ferulic acid esterase cleaves the cross-linking bonds between lignin and polysaccharides, chitinase decomposes chitin, and laccase oxidizes and degrades lignin and reduces its molecular weight, giving the lignin molecular chain segments fluidity during hot pressing, and together with thermoplastic resin, forming a strong and tough transition layer at the fiber-inorganic filler interface, thereby improving the mechanical properties of the board.

[0059] Comparative Example 1, using eucalyptus powder, has a static bending strength of 32.7 MPa and a flexural modulus of 1642 MPa. Compared to Comparative Example 1, Example 1 shows a 7.3% improvement in static bending strength and a 16% improvement in flexural modulus. The eucalyptus-bamboo hybrid powder of this application has a higher aspect ratio and better rigidity than eucalyptus fiber. After being mixed with eucalyptus fiber, it can construct a denser and interlocking reinforcing network in the resin matrix, effectively bearing and transferring external loads.

[0060] Comparative Example 5, using heavy calcium carbonate, exhibited a static bending strength of 32.8 MPa and a flexural modulus of 1712 MPa. Compared to Comparative Example 5, Example 1 showed a 7.0% improvement in static bending strength and a 12% improvement in flexural modulus. This is because the platy kaolinite microcrystals in the kaolinite-rich spherical clay are arranged in a face-to-face contact configuration within the matrix, providing physical support under stress. This enhances the rigidity and bending strength of the slab by extending the crack propagation path and dispersing stress concentration. In contrast, the granular calcite structure of heavy calcium carbonate primarily serves as a filler, contributing less to the dispersion and transmission of stress.

[0061] Comparative Example 2, which did not contain marine arthropod shells, had a static bending strength of 33.2 MPa and a flexural modulus of 1794 MPa. Compared to this comparative example, Example 1 showed an improvement of 5.7% in static bending strength and 8% in flexural modulus. Comparative Example 6, which did not contain the grinding aid sodium lignosulfonate, had a static bending strength of 33.5 MPa and a flexural modulus of 1814 MPa. Compared to this comparative example, Example 1 showed an improvement of 4.8% in static bending strength and 7% in flexural modulus.

[0062] 3. TVOC emission test: The TVOC emission of the environmentally friendly boards prepared in Examples 1-4 and Comparative Examples 1-6 was tested according to JC / T2221-2014. The results are shown in Table 3.

[0063] Table 3. Test results of TVOC emission levels As can be seen from Table 3, the TVOC release amounts in Examples 1-4 were 0.12 mg / m³, respectively. 3 0.13 mg / m 3 0.11 mg / m 3 0.11 mg / m 3 Among them, the TVOC emission level of Example 3 was the lowest, which was significantly lower than that of Comparative Examples 1 to 6, indicating that this application can significantly reduce the TVOC emission level of the board.

[0064] Comparative Example 1, using eucalyptus powder, had a TVOC release of 0.16 mg / m³. 3 Compared with Comparative Example 1, the TVOC release in Example 3 was reduced by 31.3%, indicating that the introduction of Eucalyptus chinensis into bamboo fiber is beneficial to reducing TVOC release. This is because the Eucalyptus-Eucalyptus chinensis mixed raw material system is more conducive to the dissolution of low volatile substances in the fiber during the pretreatment stage than Eucalyptus raw material alone. Comparative Example 1 only used Eucalyptus powder, which had a higher residual amount of low volatile substances, resulting in increased release after molding.

[0065] Comparative Example 3, without the addition of the 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture, had a TVOC release of 0.21 mg / m³. 3 Compared with Comparative Example 3, the TVOC release in Example 3 was reduced by 47.6%, indicating that the mixture is a key pretreatment agent for reducing TVOC release. The mixture participates in the swelling of fibers and the dissolution of low-volatile substances during the ultrasonic vibration and solvent impregnation process in S1. Without it, the removal of low-volatile substances in the pretreatment stage is insufficient, and the residual substances continue to be released after the board is formed.

[0066] Comparative Example 4, which replaced the complex enzyme preparation with laccase alone, showed a TVOC release of 0.19 mg / m³. 3 In Example 3, the TVOC release was reduced by 42.1% compared to Comparative Example 4. This is because the compound enzyme preparation effectively opened the dense fiber structure and promoted the release of low-volatile substances through multi-stage depolymerization pretreatment by chitinase, ferulic acid esterase and laccase. When laccase was used alone, the fiber depolymerization was insufficient and the low-volatile substances could not be effectively removed.

[0067] 4. Anti-mildew performance test: The environmentally friendly boards prepared in Examples 1-4 and Comparative Examples 1-6 were tested for anti-mildew level according to GB / T35469-2017. The results are shown in Table 4.

[0068] Table 4. Mildew resistance ratings for each embodiment and comparative example. As can be seen from Table 4, the anti-mildew rating of Examples 1 to 4 is all 0, indicating that this application can significantly improve the anti-mildew performance of the board.

[0069] Comparative Example 2, which did not contain dried marine arthropod shells, had a mold resistance level of 2, which was significantly lower than that of Examples 1-4 of this application. This indicates that dried marine arthropod shells can significantly improve the mold resistance of the board. This is because dried marine arthropod shells contain chitin, and the amino groups on its molecular chain can be protonated into ammonium ions, which can destroy the cell membrane of microorganisms or interfere with their metabolism, thereby inhibiting mold growth.

[0070] Comparative Example 3, which did not contain the 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture, had a mildew resistance rating of Grade 1, which was one grade lower than that of the Example. This is because the 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate in the mixture contains ammonium cation groups, which have certain antibacterial activity. Furthermore, the swelling effect of this system on the dried shells of marine arthropods in S1 helps to stretch and expose the amino groups on the chitin molecular chain, enhancing its contact efficiency with microorganisms, thereby improving the mildew resistance of the board.

[0071] The surfaces of the boards from Example 1 and Comparative Example 3 after the anti-mildew test were observed using a scanning electron microscope, and the results are as follows: Figure 5 As shown in AB.

[0072] from Figure 5 As can be seen from A, the surface of the board in Example 1 is relatively flat and dense, with only a small amount of exposed fibers and no obvious hyphae or biofilm coverage, indicating that mold is difficult to colonize and erode its surface. This is consistent with the macroscopic test results showing that the mold resistance level of Example 1 reaches level 0. From Figure 5As can be seen in B, the surface of the board in Comparative Example 3 is densely covered with a large amount of flocculent and filamentous material, forming an obvious mycelial network and biofilm. The fiber matrix is ​​severely eroded, and the surface roughness increases significantly, corresponding to a decrease in its mildew resistance level.

[0073] The VOC components released in Example 1 were analyzed by gas chromatography (GC), and the results are as follows: Figure 5 As shown in Table 4.

[0074] Table 4. VOC composition released from the board material in Example 1 from Figure 6 As can be seen, the VOC peaks in Example 1 are mainly concentrated in the retention time range of 10-30 min, which basically corresponds to the retention times (6.841-15.024 min) of the eight compounds detected in Table 4. The main components detected are 2-hydroxypropionic acid, octaldehyde, octanoic acid, nonanal, nonanol, decanal, undecaldehyde, and dodecanal, all of which are C8-C12 low-carbon fatty acids, fatty aldehydes, and fatty alcohols.

[0075] These substances mainly originate from the mild oxidation or thermal degradation of lignin, hemicellulose, and natural waxes during biopolymerization and processing, rather than toxic and harmful VOCs such as formaldehyde and benzene compounds. The absence of characteristic peaks for typical harmful substances such as benzene, toluene, and formaldehyde in the chromatogram further confirms that this invention can effectively reduce the release of harmful substances after the board is formed, ensuring the environmental safety of the product.

[0076] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing adhesive-free, environmentally friendly boards by microbial transformation of bamboo fiber, characterized in that, Includes the following steps: S1: Take fresh bamboo fiber powder, dried marine arthropod shells, and a mixture of 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium, and place them in a butanol-water solution. Under ultrasonic conditions with a frequency of 20-40 kHz and a power of 150-400 W, the mixture is shaken for 60-90 min. Then, the temperature is raised to 60℃, and 10-15 g of sodium dodecylbenzenesulfonate is added. The mixture is stirred continuously at a speed of 250 r / min for 24-96 h. After the treatment, the mixture is filtered, the filter residue is collected and washed to obtain wet fiber. S2: The wet fiber was autoclaved at 120℃ for 10 min; after sterilization, it was cooled to 60-65℃, and then adjusted to a paste-like system with a water content of 50-75% using sterilized deionized water. Then, a complex of *Clostridium thermophilum* and *Clostridium thermophilum* was added and stirred for fermentation for 24 h. After fermentation, it was cooled to 30℃, and a complex enzyme preparation was added and stirred for another 36 h to obtain bamboo fiber. Inorganic powder was added to the bamboo fiber, the temperature was raised to 80℃, and then calcium stearate was added sequentially for 30 min and trimethylchlorosilane for 30 min. After the reaction, it was cooled to room temperature and filtered to obtain fiber-inorganic composite wet powder. S3: Take the fiber-inorganic composite wet powder and put it into a high-speed ball mill, add grinding aid, grind for 20~60 h, dry after grinding to obtain modified composite powder; S4: Thermoplastic resin, modified composite powder, lubricant and moisture-absorbing masterbatch are placed in a mixer-granulator and sealed and sheared at 150°C for 60 min to obtain primary blend masterbatch; S5: The primary blending masterbatch is fed into a sheet forming machine equipped with a screw extruder for blending and extrusion to obtain an adhesive-free environmentally friendly sheet.

2. The method for preparing adhesive-free environmentally friendly boards by microbial transformation of bamboo fiber according to claim 1, characterized in that: In S1, the weight ratio of fresh bamboo fiber powder, dried marine arthropod shells, 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture, and butanol-water solution is 20:8:(2~3):

60.

3. The method for preparing adhesive-free environmentally friendly boards by microbial transformation of bamboo fiber according to claim 1, characterized in that: In S1, the fresh bamboo fiber powder is a mixture of freshly cut and crushed eucalyptus and bamboo powder, with a particle size of 120 mesh and a moisture content of 50-60%; the dried shells of marine arthropods are a mixture of one or more of crab shells, shrimp shells, and horseshoe crab shells, crushed, with a particle size of 600 mesh; the 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate / butyllithium mixture is prepared by mixing 2-hydroxy-N-(2-hydroxyethyl)-N-methylethylammonium methanesulfonate and butyllithium in a weight ratio of (4-9):1; in the butanol-water solution, the volume ratio of butanol to water is 3:

5.

4. The method for preparing adhesive-free environmentally friendly boards by microbial transformation of bamboo fiber according to claim 1, characterized in that: In S2, the weight ratio of wet fiber, inorganic powder, Clostridium thermophilum-Clostridium thermophilum complex, complex enzyme preparation, calcium stearate, and trimethylchlorosilane is 80:150:1:2:1.5:1.

5.

5. The method for preparing adhesive-free environmentally friendly boards by microbial transformation of bamboo fiber according to claim 1, characterized in that: In S2, the inorganic powder is kaolinite-rich spherical clay.

6. The method for preparing adhesive-free environmentally friendly boards by microbial transformation of bamboo fiber according to claim 1, characterized in that: The thermocrystal-thermosulfuric acid clostridium complex is composed of thermocrystal and thermosulfuric acid clostridium in a weight ratio of (4~5):1; the complex enzyme preparation is composed of chitinase, ferulic acid esterase and laccase in a weight ratio of 1:1:

3.

7. The method for preparing adhesive-free environmentally friendly boards by microbial transformation of bamboo fiber according to claim 1, characterized in that: In S3, the weight ratio of fiber-inorganic composite wet powder to grinding aid is 10:1; the grinding aid is low molecular weight sodium lignosulfonate.

8. The method for preparing adhesive-free environmentally friendly boards by microbial transformation of bamboo fiber according to claim 1, characterized in that: In S3, the ball milling conditions are: 800 r / min, forward rotation for 30 min, pause for 5 min, reverse rotation for 30 min, and cycle. The weight ratio of grinding balls to grinding material is 2:8, where the diameter of the large grinding ball is 2mm and the diameter of the small grinding ball is 0.2mm, and the weight ratio of the large grinding ball to the small grinding ball is 1:

7.

9. The method for preparing adhesive-free environmentally friendly boards by microbial transformation of bamboo fiber according to claim 1, characterized in that: In S4, the weight ratio of thermoplastic resin, modified composite powder, lubricant and moisture-absorbing masterbatch is 25:75:2.5:2.

5.

10. The method for preparing adhesive-free environmentally friendly boards by microbial transformation of bamboo fiber according to claim 1, characterized in that: In S4, the thermoplastic resin is a virgin polyethylene or polypropylene with a melt index range of 0.5~3 g / 10min, and a recycled linear low-density polyethylene composite with a melt index range of 4~8 g / 10min, with a weight ratio of 4:1; the lubricant is homopolymer low molecular weight polyethylene wax; and the moisture-absorbing masterbatch is calcium oxide-PE masterbatch.

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