Preparation method of high-performance bamboo fiber glue-free molding environment-friendly material

Abstract

The invention provides a preparation method of a high-performance bamboo fiber glue-free molding environment-friendly material, which comprises the following steps of: separating parenchyma cells and bamboo fibers from bamboo wood serving as a raw material, performing steam explosion treatment on the parenchyma cells, performing enzyme treatment on the bamboo fibers, and performing hot pressing on the treated parenchyma cells and the treated bamboo fibers to obtain the high-performance bamboo fiber glue-free molding environment-friendly material. The static bending intensity of the high-performance bamboo fiber glue-free forming environment-friendly material reaches 38.0 MPa, the elastic modulus reaches 4.9 GPa, the internal bonding strength reaches 1.8 MPa, and the water absorption thickness swelling rate is 5.0%. The preparation method is simple, the production efficiency is high, the material is rapidly formed, an adhesive is not used, the problems that a conventional fiberboard releases formaldehyde and an adhesive-free fiberboard is insufficient in performance are solved, and the fiberboard is expected to replace a traditional fiberboard to serve as a base material of a board for high-performance furniture.

Description

Technical Field

[0001] The invention belongs to the technical field of bamboo material processing and utilization, and particularly relates to a method for preparing a high-performance bamboo fiber glue-free molding environmentally friendly material. Background Art

[0002] Artificial fiberboard is widely used in furniture, construction, interior decoration and other fields due to its advantages such as light weight, high strength, easy processing and low cost. At present, artificial fiberboard such as medium-density fiberboard uses adhesives to bond fiber raw materials during the preparation process, among which urea-formaldehyde resin adhesive and phenolic resin adhesive are the main ones. Long-term use will cause the problem of formaldehyde release, which is harmful to the environment and human body. In recent years, with the growing market demand for green and environmentally friendly materials, the preparation of environmentally friendly fiber materials without adhesives has become a hot topic in current research. However, due to the weak bonding force of its own adhesive components, the performance of adhesive-free fiberboard is generally insufficient and it is difficult to meet the demand for higher performance materials. Using bamboo as raw material to prepare bamboo fiberboard with excellent comprehensive performance is one of the effective ways to solve the above problems.

[0003] Liese W, Tang TKH, Properties of the bamboo culm, Bamboo: the plant and its uses, 2015: 229 discloses that bamboo is composed of about 50% thin-walled cells, 40% fibers (thick-walled cells) and 10% vessels, and the structure is as follows Figure 1 CN 106914967 A discloses a method for preparing a non-glue reconstituted bamboo material, which comprises steaming and softening bamboo pieces or bamboo scraps and then hot-grinding them into fiber bundles, then heating and compressing the fiber bundles and transferring them into a forming mold, and heating the forming mold so that the fiber bundles therein are bonded and formed, thereby forming the non-glue reconstituted bamboo material in one step; CN 114393667A discloses a method for preparing a non-glue molded bamboo fiberboard, which comprises hot-pressing the processed bamboo material to prepare a non-glue molded bamboo fiberboard without pretreatment and without adding adhesive, but the materials obtained by the above two methods have the problems of low internal bonding strength and insufficient performance. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a high-performance bamboo fiber glue-free molding environmentally friendly material in view of the deficiencies of the above-mentioned prior art. The present invention uses bamboo as raw material to obtain a bamboo fiber self-bonding molding environmentally friendly material with excellent comprehensive performance. The preparation process is simple, the production efficiency is high, the material is quickly molded, and no adhesive is used. It is expected to replace traditional fiberboard as the base material for high-performance furniture panels.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for preparing a high-performance bamboo fiber glue-free molding environmentally friendly material comprises the following steps:

[0007] S1. Bamboo material processing: splitting bamboo tubes cut in spring and summer along the grain direction, processing into blocks, and then crushing to a particle size of 60-120 meshes to obtain bamboo powder; crushing the bamboo residue to a particle size of 60-120 meshes to obtain bamboo crushed material; then adding water to the bamboo powder and / or the bamboo crushed material, mixing and stirring, standing for 5-15 minutes, collecting the floating material on the upper layer and the precipitated material on the lower layer respectively, and drying, the floating material on the upper layer is dried to obtain powder A, which is thin-walled cells, and the precipitated material on the lower layer is dried to obtain powder B, which is bamboo fiber;

[0008] S2, thin-walled cell steam explosion treatment: the powder A obtained in S1 is mixed with water and subjected to steam explosion treatment to obtain slurry C;

[0009] S3, bamboo fiber enzyme treatment: cellulase, powder B obtained in S1 and sodium acetate buffer solution are mixed to perform enzyme treatment reaction to obtain mixture D;

[0010] S4, hot pressing molding: the slurry C obtained in S2 and the mixture D obtained in S3 are mixed evenly, and hot pressed to obtain a high-performance bamboo fiber glue-free molding environmentally friendly material.

[0011] Preferably, the water content of the powder A and powder B in S1 is 8-12%.

[0012] Preferably, the mass ratio of the powder A to water in S2 is 1:(1-5).

[0013] Preferably, the explosion pressure of the steam explosion treatment in S2 is 1.0-2.0 MPa, and the pressure holding time is 2-9 min.

[0014] Preferably, the mass ratio of the cellulase, powder B and sodium acetate buffer solution in S3 is (0.5-6):100:(150-300).

[0015] Preferably, the enzyme treatment reaction conditions in S3 are: stirring at a temperature of 40-60°C for 0.5-8h and a stirring rate of 30-60r / min, and then raising the temperature to 70-100°C and maintaining it for 10-30min.

[0016] Preferably, the mass ratio of the slurry C and the mixture D in S4 is 1:(0.5-2).

[0017] Preferably, the upper and lower surfaces of the hot pressing mold in S4 are designed with evenly distributed exhaust holes, the exhaust holes are arranged in a grid shape, the exhaust hole spacing is 5 to 20 mm, the exhaust hole diameter is 0.05 to 1 mm, and the air guide speed is 10 to 50 mL / min.

[0018] Preferably, the temperature of the hot pressing treatment in S4 is 160-220° C., the pressure is 15-25 MPa, and the hot pressing time is 2-15 min / mm.

[0019] The invention also provides a high-performance bamboo fiber glue-free molding environmentally friendly material prepared by the method.

[0020] The present invention has the following significant technical effects:

[0021] 1. The present invention uses bamboo as raw material and adopts a self-bonding process to obtain a bamboo fiber glue-free molding environmentally friendly material with excellent comprehensive performance. Its static bending strength reaches 38.0MPa, elastic modulus reaches 4.9GPa, internal bonding strength reaches 1.8MPa, and water absorption thickness expansion rate is 5.0%. The preparation method of the high-performance bamboo fiber glue-free molding environmentally friendly material of the present invention is simple, the production efficiency is high, the material is quickly molded, and no adhesive is used. It solves the problems of formaldehyde release of conventional fiberboard and insufficient performance of glue-free fiberboard, and is expected to replace traditional fiberboard as the base material of high-performance furniture board.

[0022] 2. Steam explosion treatment reduces the hemicellulose content of bamboo thin-wall cells and significantly increases the lignin content. The hemicellulose in the thin-wall cells decomposes polysaccharides during the steam explosion process and further forms furfural, acetic acid and other substances. During the hot pressing process, furfural resins have an adhesive effect on bamboo fibers and also react with lignin in bamboo fibers to form phenolic resins, thereby achieving adhesion to bamboo fibers. At the same time, furfural can also be hydrogenated to form furfuryl alcohol, which reacts with lignin to form phenol-furan resins, promoting the self-binding of bamboo fibers.

[0023] 3. Enzyme treatment can form abundant sub-fiber branches on the surface of bamboo fiber, making it easier to form entanglement and bridging structures, forming a more stable framework structure, and improving the strength of the material. In addition, enzyme treatment can release more aldehyde groups and active hydroxyl groups in bamboo fiber, which is beneficial to the hydrogen bond between bamboo fibers. This hydrogen bond network enables bamboo fiber to form stronger bonding force during hot pressing.

[0024] The present invention is further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a bamboo structure diagram of the present invention;

[0026] Figure 21 is a scanning electron microscope image of untreated bamboo thin-walled cells (A) and untreated bamboo fibers (B) of Example 1, a: thin-walled cells, b: bamboo fibers, c: thin-walled cell particles, d: bamboo fiber particles;

[0027] Figure 3 is an electron microscopic image of different morphologies of bamboo parenchyma cells (C) after steam explosion treatment in Example 1;

[0028] Figure 4 The electron microscope images of the untreated (B) and enzyme-treated (D) bamboo fibers of Example 1, a: untreated bamboo fibers, b: enzyme-treated bamboo fibers;

[0029] Figure 5 This is a physical picture of the bamboo fiber glue-free molding environmentally friendly material (C+D) of Example 1 supporting a 25kg weight;

[0030] Figure 6 The electron microscope images of the high-performance bamboo fiber glue-free molding environmentally friendly material (C+D) of Example 1, a: material surface, b: material cross section;

[0031] Figure 7 It is the electron microscope image of the adhesive-free molding material (A+D) of comparative example 1, a: material surface, b: material cross section;

[0032] Figure 8 It is a micro-CT image of the high-performance bamboo fiber glue-free molding environmentally friendly material (C+D) of Example 1, a: two-dimensional plane scanning slice, b: cross-sectional image after threshold segmentation extraction, c: three-dimensional reconstruction model;

[0033] Fig. 9 These are micro-CT images of the bamboo fiber glue-free molding material (A+D) of comparative example 1, a: two-dimensional plane scanning slice, b: cross-sectional image after threshold segmentation extraction, c: three-dimensional reconstruction model;

[0034] Fig.10 This is an electron microscope image of the bamboo fiber glue-free molding material (A+B) of comparative example 2, a: material surface, b: material internal structure;

[0035] Fig.11 This is an electron microscope image of the bamboo fiber glue-free molding material (A) of comparative example 3, a: material surface, b: material internal structure. DETAILED DESCRIPTION

[0036] Example 1

[0037] This embodiment is a method for preparing a high-performance bamboo fiber glue-free molding environmentally friendly material, comprising the following steps:

[0038] S1. Bamboo material processing: split the bamboo tubes cut in spring and summer along the grain direction, process them into blocks, and then grind them into a particle size of 60-120 meshes to obtain bamboo powder; grind the bamboo residue into a particle size of 60-120 meshes to obtain bamboo crushed material; then add water to the bamboo powder and / or the bamboo crushed material, mix and stir, let it stand for 15 minutes, collect the floating material on the upper layer and the precipitated material on the lower layer, respectively, and dry them at a temperature of 60°C for 4 hours. After drying the floating material on the upper layer, powder A is obtained, which is thin-walled cells, and after drying the precipitated material on the lower layer, powder B is obtained, which is bamboo fiber. The water content of powders A and B is 10%.

[0039] S2. Steam explosion treatment of thin-walled cells: Powder A obtained in S1 was mixed with water in a mass ratio of 1:5, and steam explosion treatment was performed with a blasting pressure of 2.0 MPa and a pressure holding time of 5 min to obtain slurry C, in which the lignin content in the solid matter was more than 35% and the pH value of the liquid was 3-6.

[0040] S3. Enzyme treatment of bamboo fiber: cellulase, powder B obtained in S1 and sodium acetate buffer solution were mixed in a mass ratio of 6:100:300, stirred in a reactor at a temperature of 60°C for 8 hours at a stirring rate of 60 r / min, and then the temperature was raised to 100°C and maintained for 20 minutes to obtain a mixture D.

[0041] S4, hot pressing molding: The slurry C obtained in S2 and the mixture D obtained in S3 are evenly mixed in a mass ratio of 1:1, and then hot pressed under the process conditions of temperature 180°C, pressure 20MPa, and 5min / mm to obtain a high-performance bamboo fiber glue-free molding environmentally friendly material (C+D).

[0042] The upper and lower surfaces of the hot pressing mold used in the present invention are designed with evenly distributed exhaust holes, which are arranged in a grid shape, with an exhaust hole spacing of 5 to 20 mm, ensuring that the gas is evenly discharged from the surface of the material, the exhaust hole aperture is 0.05 to 1 mm, and the air guide speed is 10 to 50 mL / min, ensuring that the gas can be discharged smoothly during the hot pressing process, avoiding bubbling and stratification inside the material, improving the yield rate of the hot pressing molding of the material, and finally obtaining the bamboo fiber self-bonding molding environmentally friendly material. The air guide technology is conducive to making the material more compact under hot pressing by discharging excess water vapor and moisture during the hot pressing molding process, improving the density of the material and the uniformity of the internal structure, and enhancing the comprehensive performance of the material.

[0043] The parenchyma cells and fibers of bamboo have significant differences in microstructure, chemical composition and properties. Figure 2The following are scanning electron microscope images of untreated parenchyma cells (A) and untreated bamboo fibers (B). The parenchyma cell wall is thin, the cavity is large, and there are many pits. The cellulose fibrils in the wall layer are loosely arranged, and the cavity contains abundant starch granules. The fiber wall is thick, the cavity is small, and there are few pits. The cellulose fibrils in the wall layer are tightly arranged, and there are no starch granules in the cavity. In addition, the density of parenchyma cells is low, the mechanical properties are weak, and they are easily damaged. After testing, the chemical composition of parenchyma cells and bamboo fibers is shown in Table 1. Compared with fibers, parenchyma cells have higher lignin and hemicellulose contents, while cellulose content and relative cellulose crystallinity are lower. In addition, the lignin in parenchyma cells is more easily degraded, and the hemicellulose has a higher degree of branching and different composition units.

[0044] Table 1 Chemical composition of parenchyma cells and bamboo fibers

[0045] name Cellulose(%) Hemicellulose (%) Lignin(%) Thin-walled cells 36 20 27 Bamboo Fiber 38 17 25

[0046] Figure 3 The different forms of thin-walled cells (C) after steam explosion treatment show smaller spherical particles and a rougher surface, which is conducive to the connection between fibers and pore filling. The changes in the composition of thin-walled cells after steam explosion treatment are shown in Table 2. After steam explosion treatment, the hemicellulose content of the thin-walled cells is reduced, and the lignin is greatly increased. The substances decomposed by the hemicellulose are acidic, and the acidic environment is conducive to the reaction of substances and self-binding. At the same time, lignin softens when it reaches the glass transition temperature (above 170°C), melts and flows, and solidifies when the temperature decreases to form a bonding effect. Therefore, the increase in lignin content plays an important role in self-binding. The hemicellulose in the thin-walled cells decomposes polysaccharides during the steam explosion process and further forms furfural, acetic acid and other substances. During the hot pressing process, furfural resinization has an adhesive effect on bamboo fibers, and also undergoes a condensation reaction with the lignin in the bamboo fibers to form phenolic resins, thereby achieving adhesion to the bamboo fibers; at the same time, furfural can also be hydrogenated to form furfuryl alcohol, and furfuryl alcohol reacts with lignin to form phenol-furan resin, which promotes the self-binding of bamboo fibers. In addition, during the hot pressing process of the spherical structure of the thin-walled cells, a mechanical locking effect is formed between the fibers, which also promotes the formation of a good bond between the bamboo fibers. Therefore, high-strength bamboo fibers are used as the reinforcement phase as the mechanical bearing unit. Based on the fact that the thin-walled cell structure is easily destroyed, the thin-walled cells are activated by pretreatment to produce more substances that are conducive to bonding to provide bonding. At the same time, the mechanical locking effect of the thin-walled cells is used to prepare high-performance bamboo fiber glue-free molding materials.

[0047] Table 2 Changes in parenchyma cell composition after steam explosion

[0048] Processing conditions Cellulose Hemicellulose Lignin Unprocessed 36 20 27 Steam explosion treatment 35 15 36

[0049] Figure 4The electron microscope images of bamboo fibers before (B) and after (D) enzyme treatment show that enzyme treatment can form abundant sub-fiber branches on the surface of bamboo fibers, making it easier to form entanglement and bridging structures, forming a more stable framework structure, and improving the strength of the material. Cellulase treatment releases more aldehyde groups and active hydroxyl groups in bamboo fibers. During the hot pressing process, the number of aldehyde groups and active hydroxyl groups on the cellulose molecular chain in bamboo fibers increases, which is conducive to the hydrogen bonding between bamboo fibers. This hydrogen bond network enables bamboo fibers to form stronger bonding during the hot pressing process.

[0050] Figure 5 This is a physical picture of the bamboo fiber glue-free molding environmentally friendly material (C+D) of Example 1 supporting a 25kg weight.

[0051] Comparative Example 1

[0052] A method for preparing a bamboo fiber glue-free molding material comprises the following steps:

[0053] S1. Bamboo material processing: split the bamboo tubes cut in spring and summer along the grain direction, process them into blocks, and then grind them into a particle size of 60-120 meshes to obtain bamboo powder; grind the bamboo residue into a particle size of 60-120 meshes to obtain bamboo crushed material; then add water to the bamboo powder and / or the bamboo crushed material, mix and stir, let it stand for 15 minutes, collect the floating material on the upper layer and the precipitated material on the lower layer, respectively, and dry them at a temperature of 60°C for 4 hours. After drying the floating material on the upper layer, powder A is obtained, which is thin-walled cells, and after drying the precipitated material on the lower layer, powder B is obtained, which is bamboo fiber. The water content of powders A and B is 9%.

[0054] S2. Enzyme treatment of bamboo fiber: cellulase, powder B obtained in S1 and sodium acetate buffer solution were mixed in a mass ratio of 6:100:300, stirred in a reactor at a temperature of 60°C for 8 hours at a stirring rate of 60 r / min, and then the temperature was raised to 100°C and maintained for 20 minutes to obtain a mixture D.

[0055] S3, hot pressing molding: The powder A obtained in S1 and the mixture D obtained in S2 are evenly mixed in a mass ratio of 1:1, and then hot pressed under the process conditions of temperature 180°C, pressure 20MPa, and 5min / mm to obtain a bamboo fiber glue-free molding material (A+D).

[0056] Figure 6 This is an electron microscope image of the high-performance bamboo fiber glue-free molding environmentally friendly material (C+D) obtained in Example 1, wherein Figure 6 a is the material surface, Figure 6 b is the material cross section. Figure 7 This is an electron microscope image of the bamboo fiber glue-free molding material (A+D) obtained in Comparative Example 1, wherein Figure 7 a is the material surface, Figure 7 b is the cross section of the material. Figure 6 and Figure 7 It can be seen that the material prepared by steam explosion treatment of thin-walled cells has a smoother surface and a denser interior. Such a structure gives the material superior physical and mechanical properties.

[0057] Figure 8 The micro-CT images of the high-performance bamboo fiber glue-free molding environmentally friendly material (C+D) obtained in Example 1, a: two-dimensional plane scanning slice, b: cross-sectional image after threshold segmentation extraction, c: three-dimensional reconstruction model. Fig. 9 These are micro-CT images of the bamboo fiber glue-free molding material (A+D) obtained in Comparative Example 1, a: two-dimensional plane scanning slice, b: cross-sectional image after threshold segmentation extraction, c: three-dimensional reconstructed model. Figure 8 and Fig. 9 The CT images show that the material prepared by steam explosion of thin-walled cells has fewer internal pores and is more tightly bound, with the reduction of large pores being particularly obvious, which is crucial for a significant improvement in the physical and mechanical properties of the material.

[0058] Comparative Example 2

[0059] A method for preparing a bamboo fiber glue-free molding material comprises the following steps:

[0060] S1. Bamboo material processing: the bamboo tubes cut down in spring and summer are split along the grain direction, processed into blocks, and then crushed to a particle size of 60-120 meshes to obtain bamboo powder; the bamboo residue is crushed to a particle size of 60-120 meshes to obtain bamboo crushed material; the bamboo powder and / or bamboo crushed material are mixed with water and stirred, and then allowed to stand for 15 minutes, and the floating material on the upper layer and the precipitated material on the lower layer are collected respectively, and dried at a temperature of 60° C. for 4 hours. After the floating material on the upper layer is dried, powder A is obtained, which is thin-walled cells, and after the precipitated material on the lower layer is dried, powder B is obtained, which is bamboo fiber, and the water content of powders A and B is 11%.

[0061] S2. Hot pressing molding: Powder A obtained from S1 and powder B obtained from S2 are evenly mixed in a mass ratio of 1:1, and then hot pressed under process conditions of temperature 1800°C, pressure 20 MPa, and 5 min / mm to obtain bamboo fiber glue-free molding material (A+B).

[0062] Fig.10 This is the electron microscope image of the bamboo fiber glue-free molding material (A+B) obtained in Comparative Example 2, a: material surface, b: material internal structure.

[0063] Comparative Example 3

[0064] A method for preparing a bamboo fiber glue-free molding material comprises the following steps:

[0065] S1. Bamboo material processing: split the bamboo tubes cut in spring and summer along the grain direction, process them into blocks, and then grind them into a particle size of 60-120 meshes to obtain bamboo powder; grind the bamboo residue into a particle size of 60-120 meshes to obtain bamboo crushed material; then add water to the bamboo powder and / or the bamboo crushed material, mix and stir, let it stand for 15 minutes, collect the floating material on the upper layer and the precipitated material on the lower layer, respectively, and dry them at a temperature of 60°C for 4 hours. After drying the floating material on the upper layer, powder A is obtained, which is thin-walled cells, and after drying the precipitated material on the lower layer, powder B is obtained, which is bamboo fiber. The water content of powders A and B is 10%.

[0066] S2. Hot pressing: The powder B is hot pressed under the process conditions of temperature of 180° C., pressure of 20 MPa, and 5 min / mm to obtain a bamboo fiber glue-free molding material (B).

[0067] Fig.11 This is an electron microscope image of the bamboo fiber glue-free molding material (B) obtained in Comparative Example 3, a: material surface, b: material internal structure.

[0068] The performance of the bamboo fiber glue-free molding materials prepared in Example 1 and Comparative Examples 1 to 3 was tested, and the results are shown in Table 3.

[0069] Table 3 Properties of different bamboo fiber glue-free molding materials

[0070]

[0071]

[0072] The thickness of the bamboo fiber glue-free molding material prepared above is within the range of 3.5 to 6 mm, and different thicknesses can be produced according to actual production needs. As shown in Table 3, the present invention obtains a high-density bamboo fiber glue-free molding environmentally friendly material with excellent comprehensive performance, and its static bending strength reaches 38.0 MPa, elastic modulus reaches 4.9 GPa, internal bonding strength reaches 1.8 MPa, and water absorption thickness expansion rate is 5.0%.

[0073] Example 2

[0074] This embodiment is a method for preparing a high-performance bamboo fiber glue-free molding environmentally friendly material, comprising the following steps:

[0075] S1. Bamboo material processing: split the bamboo tubes cut in spring and summer along the grain direction, process them into blocks, and then grind them into a particle size of 60-120 meshes to obtain bamboo powder; grind the bamboo residue into a particle size of 60-120 meshes to obtain bamboo crushed material; then add water to the bamboo powder and / or the bamboo crushed material, mix and stir, let it stand for 5 minutes, collect the floating material on the upper layer and the precipitated material on the lower layer, respectively, and dry them at a temperature of 80° C. for 2 hours. After drying the floating material on the upper layer, powder A is obtained, which is thin-walled cells, and after drying the precipitated material on the lower layer, powder B is obtained, which is bamboo fiber. The water content of powders A and B is 8%.

[0076] S2. Steam explosion treatment of thin-walled cells: Powder A obtained in S1 was mixed with water in a mass ratio of 1:1, and steam explosion treatment was performed with a blasting pressure of 1.0 MPa and a holding time of 9 min to obtain slurry C, in which the lignin content in the solid matter was more than 35% and the pH value of the liquid was 3-6.

[0077] S3. Enzyme treatment of bamboo fiber: cellulase, powder B obtained in S1 and sodium acetate buffer solution were mixed in a mass ratio of 0.5:100:150, stirred in a reactor at a temperature of 40°C for 4 hours at a stirring rate of 30 r / min, and then the temperature was raised to 70°C and maintained for 30 minutes to obtain a mixture D.

[0078] S4, hot pressing molding: the slurry C obtained in S2 and the mixture D obtained in S3 are evenly mixed in a mass ratio of 1:2, and then hot pressed under process conditions of temperature 220° C., pressure 15 MPa, and 15 min / mm to obtain a high-performance bamboo fiber glue-free molding environmentally friendly material.

[0079] Example 3

[0080] This embodiment is a method for preparing a high-performance bamboo fiber glue-free molding environmentally friendly material, comprising the following steps:

[0081] S1. Bamboo material processing: split the bamboo tubes cut in spring and summer along the grain direction, process them into blocks, and then grind them into a particle size of 60-120 meshes to obtain bamboo powder; grind the bamboo residue into a particle size of 60-120 meshes to obtain bamboo crushed material; then add water to the bamboo powder and / or the bamboo crushed material, mix and stir, let it stand for 10 minutes, collect the floating material on the upper layer and the precipitated material on the lower layer, respectively, and dry them at a temperature of 70°C for 3 hours. After drying the floating material on the upper layer, powder A is obtained, which is thin-walled cells, and after drying the precipitated material on the lower layer, powder B is obtained, which is bamboo fiber. The water content of powders A and B is 12%.

[0082] S2. Steam explosion treatment of thin-walled cells: Powder A obtained in S1 was mixed with water in a mass ratio of 1:3, and steam explosion treatment was performed with a blasting pressure of 1.5 MPa and a pressure holding time of 2 min to obtain slurry C, in which the lignin content in the solid matter was more than 35%, and the pH value of the liquid was 3-6.

[0083] S3. Enzyme treatment of bamboo fiber: cellulase, powder B obtained in S1 and sodium acetate buffer solution were mixed in a mass ratio of 2:100:240, stirred in a reactor at a temperature of 50°C for 0.5h at a stirring rate of 50r / min, and then the temperature was raised to 90°C and maintained for 10min to obtain a mixture D.

[0084] S4, hot pressing molding: the slurry C obtained in S2 and the mixture D obtained in S3 are mixed evenly in a mass ratio of 1:1, and then hot pressed under the process conditions of temperature 160°C, pressure 25MPa, and 2min / mm to obtain a high-performance bamboo fiber glue-free molding environmentally friendly material.

[0085] The present invention uses bamboo as raw material and adopts a self-bonding process to obtain an environmentally friendly bamboo fiber non-glue molding material with excellent comprehensive performance. The preparation method is simple, the production efficiency is high, the material is quickly molded, and no aldehyde-containing adhesive is used. Steam explosion treatment of thin-walled cells is conducive to promoting the self-bonding of bamboo fibers, and the physical and mechanical properties of the obtained material are greatly improved; enzyme treatment can form abundant sub-fiber branches on the surface of bamboo fibers, which is easier to form winding and bridging structures, forming a more stable frame structure, and improving the strength of the material. The present invention solves the problems of formaldehyde release of conventional fiberboards and insufficient performance of non-glue fiberboards, and is expected to replace traditional fiberboards as the base material for high-performance furniture panels.

[0086] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing high-performance bamboo fiber glue-free molding environmentally friendly material, characterized in that: The method comprises the following steps: S1. Bamboo material processing: splitting bamboo tubes cut in spring and summer along the grain direction, processing into blocks, and then crushing to a particle size of 60-120 meshes to obtain bamboo powder; crushing the bamboo residue to a particle size of 60-120 meshes to obtain bamboo crushed material; then adding water to the bamboo powder and / or the bamboo crushed material, mixing and stirring, standing for 5-15 minutes, collecting the floating material on the upper layer and the precipitated material on the lower layer respectively, and drying, the floating material on the upper layer is dried to obtain powder A, which is thin-walled cells, and the precipitated material on the lower layer is dried to obtain powder B, which is bamboo fiber; S2, thin-walled cell steam explosion treatment: the powder A obtained in S1 is mixed with water and subjected to steam explosion treatment to obtain slurry C; S3, bamboo fiber enzyme treatment: cellulase, powder B obtained in S1 and sodium acetate buffer solution are mixed to perform enzyme treatment reaction to obtain mixture D; S4, hot pressing molding: the slurry C obtained in S2 and the mixture D obtained in S3 are mixed evenly, and hot pressed to obtain a high-performance bamboo fiber glue-free molding environmentally friendly material.

2. The method according to claim 1, characterized in that S1 The water content of the powder A and the powder B is 8-12%.

3. The method according to claim 1, characterized in that The mass ratio of powder A to water in S2 is 1:(1-5).

4. The method according to claim 1, characterized in that: The explosion pressure of the steam explosion treatment in S2 is 1.0-2.0 MPa, and the pressure holding time is 2-9 min.

5. The method according to claim 1, characterized in that The mass ratio of cellulase, powder B and sodium acetate buffer solution in S3 is (0.5-6):100:(150-300).

6. The method according to claim 1, characterized in that The enzyme treatment reaction conditions in S3 are: stirring at a temperature of 40-60°C for 0.5-8h and a stirring rate of 30-60r / min, and then raising the temperature to 70-100°C and maintaining it for 10-30min.

7. The method according to claim 1, characterized in that The mass ratio of the slurry C and the mixture D in S4 is 1:(0.5-2).

8. The method according to claim 1, characterized in that S4 The upper and lower surfaces of the hot pressing mold are designed with evenly distributed exhaust holes, which are arranged in a grid shape, with an exhaust hole spacing of 5 to 20 mm, an exhaust hole diameter of 0.05 to 1 mm, and an air guide speed of 10 to 50 mL / min.

9. The method according to claim 1, characterized in that: The temperature of the hot pressing treatment in S4 is 160-220° C., the pressure is 15-25 MPa, and the hot pressing time is 2-15 min / mm.

10. A high-performance bamboo fiber glue-free molding environmentally friendly material prepared by the method according to any one of claims 1 to 9.

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