Preparation method of high-modulus modified thin bamboo green material and laminated board

Abstract

This invention provides a method for preparing high-modulus modified thin bamboo veneer and laminates. The method improves the material's modulus, toughness, and bonding properties while retaining the bamboo veneer. A green and environmentally friendly eutectic solvent, a compound solution of choline chloride, glycerol, and aluminum chloride hexahydrate, is used to impregnate the ultrasonically treated bamboo veneer sheets. Under specific temperature and time conditions, some lignin in the main components is removed, and the waxy layer and SiO2 on the bamboo veneer surface react chemically with the solvent components to form new silicides, significantly increasing the modulus. The waxy layer, which affects bonding, dissolves or is removed, resulting in a viscous lamination on the surface. The porosity of the main cells in the inner layer increases, facilitating subsequent bonding or other impregnation treatments, thus enabling controllable board structure and properties. The high-strength and tough modified bamboo veneer unit prepared by this invention does not require de-greening treatment, improving bamboo utilization.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bamboo processing, and particularly relates to a preparation method of high-modulus modified thin bamboo-green material and laminated board. BACKGROUND

[0002] Bamboo is the most Chinese characteristic non-wood forest resources, has the advantages of fast growth, good mechanical properties, high carbon fixation capacity, etc., and is widely used in the fields of building, furniture, etc. However, the bamboo green on the outer surface of the bamboo has a wax layer and a siliceous layer, which has a great influence on the gluing performance, so the bamboo green needs to be removed during the initial processing, and then subsequent gluing and hot pressing processes are carried out, resulting in a very low yield of bamboo board, which directly affects the processing cost. Even the bamboo green flat material needs to remove the bamboo green through sanding and planing processes before the board is made, and sometimes there are as many as ten to twenty processes from material processing to product forming, which greatly increases the production cost.

[0003] At present, the modification method for improving the modulus of bamboo mainly is to treat the bamboo through physical or chemical means and then densify, which has the problems of relatively complex process and high cost. The unit after densification has high modulus and good strength, but there are still great problems in toughness and dimensional stability, and many materials produced by this method have high springback rate and poor dimensional stability.

[0004] To solve the above problems, the application provides a preparation method of high-modulus modified thin bamboo-green material and laminated board. SUMMARY

[0005] The technical problem to be solved by the application is to provide a preparation method of high-modulus modified thin bamboo-green material and laminated board, which solves the problems of the prior art. The preparation method uses a eutectic solvent solution of choline chloride, glycerol and aluminum chloride hexahydrate to impregnate the ultrasonic bamboo-green thin sheet and the ultrasonic bamboo-green flat thin sheet, removes part of lignin in the main components under the condition of water bath at a certain temperature and for a certain time, and makes the wax layer and SiO2 on the surface of the bamboo green chemically react with the components in the eutectic solvent solution to form new silicides, so that the modulus is significantly increased. At the same time, the wax layer affecting gluing is dissolved or removed, a viscous flow-like sediment is generated on the surface layer, the porosity of the main cells in the inner layer is increased, and the next step of gluing or other impregnation treatment is easy, so that the structure and performance of the board can be adjusted and controlled. The static bending strength, elastic modulus and bending toughness of the prepared high-modulus modified thin bamboo-green material are all improved.

[0006] To solve the above technical problems, the technical scheme adopted by the application is as follows: a preparation method of high-modulus modified thin bamboo-green material, which comprises the following steps:

[0007] S1, removing the outer node and the inner node of the felled bamboo, longitudinally splitting the bamboo into bamboo pieces, removing the bamboo yellow from the bamboo pieces without removing the bamboo green, and then drying to obtain pretreated bamboo pieces;

[0008] Then a part of the pretreated bamboo pieces is subjected to saturated steam softening treatment, flattened, and then subjected to hot air drying to obtain a bamboo flattened plate;

[0009] S2, the pretreated bamboo pieces obtained in S1 and the bamboo flattened plate obtained in S1 are both split along the chord direction, and then subjected to ultrasonic treatment at room temperature to obtain ultrasonic-treated bamboo green sheet material and ultrasonic-treated bamboo flattened sheet material with green respectively;

[0010] S3, choline chloride, glycerol and aluminum chloride hexahydrate are mixed and stirred at a certain temperature to obtain a transparent DES solvent composite solution;

[0011] The transparent DES solvent composite solution and deionized water are mixed to obtain a deep eutectic solvent solution;

[0012] S4, the ultrasonic-treated bamboo green sheet material obtained in S2 and the ultrasonic-treated bamboo flattened sheet material with green obtained in S2 are both immersed in the deep eutectic solvent solution obtained in S3 under water bath conditions, washed with distilled water after taking out, and then dried to obtain original high modulus modified thin bamboo green material and flattened high modulus modified thin bamboo green material respectively.

[0013] Preferably, the drying temperature in S1 is 25-30℃, and the time is 24h; the thickness of the pretreated bamboo pieces is 6-7mm.

[0014] Preferably, the saturated steam softening treatment temperature in S1 is 160-180℃, and the time is 15min; the hot air drying temperature is 60℃, and the time is 30min.

[0015] Preferably, the ultrasonic treatment frequency in S2 is 30-50KHz, the power is 180-400W, and the treatment time is 10-15min.

[0016] Preferably, the molar ratio of choline chloride, glycerol and aluminum chloride hexahydrate in S3 is 1:2:0.05; the stirring rate is 100-1000rpm under the condition of stirring at the temperature of 100℃ for 30min; the volume ratio of the transparent DES solvent composite solution and deionized water is 3:7.

[0017] Preferably, the water bath temperature in S4 is 60-90℃, and the immersion time is 1-5h.

[0018] Preferably, the drying in S4 is air drying or freeze drying, wherein the air drying time is 8-12 hours, and the freeze drying temperature is -80°C for 12 hours.

[0019] This invention also provides a method for preparing laminates using the high-modulus modified thin bamboo veneer prepared above, the method comprising the following steps:

[0020] Adhesive is applied to either the green or yellow side of the two pieces of high-modulus modified thin bamboo green material, and then they are placed in a hot press for hot pressing and bonding to obtain a high-modulus modified thin bamboo green material laminate.

[0021] This invention also provides a method for preparing laminates using the flattened high-modulus modified thin bamboo veneer prepared above, the method comprising the following steps:

[0022] Adhesive is applied to either the bamboo green side or the bamboo yellow side of two pieces of flattened high modulus modified thin bamboo green material, and then they are placed in a hot press for hot pressing and bonding to obtain flattened high modulus modified thin bamboo green material laminate.

[0023] Preferably, the hot-press bonding temperature is 120-140℃, the time is 5-10 min, and the pressure is 0.5-3 MPa; the adhesive is a phenolic resin adhesive or an isocyanate adhesive, and the adhesive application amount is 150 g / m². 2 .

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] Currently, in the bamboo processing industry, the waxy layer on the surface of bamboo affects the bonding performance. During the initial processing, it is necessary to remove the bamboo green and bamboo yellow, which leads to a low yield. While processes such as slicing or sanding remove the bamboo green that affects bonding, they also remove the strongest part of the bamboo. This not only affects the overall mechanical properties of the bamboo but also greatly reduces the yield and increases the number of processing steps.

[0026] To address the above issues, this invention employs a green and environmentally friendly eutectic solvent to impregnate ultrasonically treated bamboo green sheet and ultrasonically treated flattened bamboo green sheet. This process removes the waxy layer from the bamboo green side while exposing the fibrous portion on the surface, increasing roughness. A non-uniformly distributed cement-like silica layer forms on the surface, facilitating adhesive bonding under high temperatures. This silica layer also improves the modulus and strength of the bamboo unit. On the bamboo yellow side, more lignin is exposed on the surface, and the pore size of the thin-walled cells increases, facilitating adhesive penetration while enhancing the toughness of the bamboo unit, making it less prone to deformation or breakage. The eutectic solvent used in this invention is composed of common choline chloride, glycerol, and aluminum chloride hexahydrate. It is stable, environmentally friendly, and easy to operate. It modifies bamboo under mild conditions, resulting in improvements in multiple indicators such as modulus, strength, and toughness. Furthermore, it allows for direct gluing without removing the bamboo green layer, thus increasing the utilization rate of bamboo. The eutectic solvent solution is recyclable, reducing processing steps and lowering production costs. This provides a feasible solution for the use of bamboo in the construction and home furnishing industries.

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0028] Figure 1 This invention describes the changes in C, O, and Si elements on the surface of high-modulus modified thin bamboo green material obtained under different processing times.

[0029] Figure 2 It refers to the change in porosity of bamboo flattened boards before and after the flattening process.

[0030] Figure 3 This refers to the change in functional groups on the bamboo green side of the high-modulus modified thin bamboo green material obtained in Example 1 of this invention.

[0031] Figure 4 This refers to the change in functional groups on the bamboo yellow side of the high-modulus modified thin bamboo green material obtained in Example 1 of this invention.

[0032] Figure 5 This is a photograph of the high-modulus modified thin bamboo laminate prepared in Example 1 of the present invention. Detailed Implementation

[0033] Example 1

[0034] The method for preparing high-modulus modified thin bamboo greenwood and laminate in this embodiment includes the following steps:

[0035] S1. Remove the outer and inner nodes of the harvested raw bamboo, then longitudinally split it into bamboo strips. Remove the bamboo yellow but not the bamboo green from the bamboo strips, stack them at intervals, and dry them at 27°C for 24 hours to obtain pre-treated bamboo strips with a thickness of 6-7 mm.

[0036] A portion of the pretreated bamboo strips are placed in a steam tank and subjected to saturated steam softening treatment at a temperature of 170°C for 15 minutes to reach a softened and plastic state. After being taken out, they are flattened in a unfolding machine and then dried with hot air at a temperature of 60°C for 30 minutes. They are then bound with rigid straps or stacked with heavy objects to constrain them and prevent deformation, thus obtaining bamboo flattened boards.

[0037] S2. The pretreated bamboo strips and the bamboo flattening boards obtained in S1 are split along the tangential direction into pretreated bamboo green sheet with a thickness of 2 mm and bamboo flattening sheet with a thickness of 1.5 mm. Then, they are subjected to ultrasonic treatment for 12 min at room temperature (25℃). The frequency of ultrasonic treatment is 40KHz and the power is 300W. Ultrasonic bamboo green sheet and ultrasonic bamboo flattening sheet with green are obtained respectively.

[0038] S3. Mix choline chloride (ChCl), glycerol (Gly), and aluminum chloride hexahydrate (AlCl3·6H2O) in a molar ratio of 1:2:0.05, and then stir at 100℃ for 30 min at a stirring speed of 600 rpm to obtain a transparent DES solvent composite solution.

[0039] The transparent DES solvent composite solution and deionized water are mixed in a volume ratio of 3:7 to obtain a eutectic solvent solution with a pH value of 6.5.

[0040] S4. The ultrasonically treated bamboo green sheet and the ultrasonically treated bamboo green sheet obtained in S2 were both immersed in the eutectic solvent solution obtained in S3 at a water bath temperature of 90℃ for 5 hours. After immersion, they were taken out and rinsed with distilled water until there was no eutectic solvent solution residue on the surface, and then air-dried for 10 hours to obtain the original high modulus modified thin bamboo green material and the flattened high modulus modified thin bamboo green material, respectively.

[0041] The eutectic solvent solution after impregnation can be recycled 1-5 times. When recycling, the impregnation time should be extended by 0.5 hours each time.

[0042] S5. Apply phenolic resin adhesive to the bamboo green side of one piece of the aforementioned high-modulus modified thin bamboo green material, and apply phenolic resin adhesive to the bamboo yellow side of another piece of the aforementioned high-modulus modified thin bamboo green material, with an adhesive application amount of 150g / m² for both. 2Then, the material is hot-pressed and bonded using a hot press at a temperature of 130℃ for 7 minutes and a pressure of 2MPa to obtain a high-modulus modified thin bamboo greenwood laminate. Figure 5 (As shown).

[0043] The high-modulus modified thin bamboo laminate prepared in this embodiment has an elastic modulus of 13.3 GPa, a static bending strength of 269 MPa, and a bending toughness of 102 W.

[0044] The mechanical properties of the bamboo green side of the high modulus modified thin bamboo green material and the bamboo green flattened thin bamboo green material prepared by immersing them in a eutectic solvent solution for different times are different. The results are shown in Table 1.

[0045] Table 1 Mechanical properties of high-modulus modified thin bamboo greenwood obtained under different treatment times

[0046]

[0047] As shown in Table 1, the elastic modulus of the high-modulus modified thin bamboo stalks obtained after impregnation treatment increased by approximately 71.82%, but the bending toughness decreased after impregnation time exceeding 5 hours. The modulus and toughness of the flattened high-modulus modified thin bamboo stalks (bamboo stalk side) obtained after treatment were both improved.

[0048] Figure 1 The changes in C, O, and Si elements on the bamboo green side of the high-modulus modified thin bamboo green material obtained by ultrasonic treatment of bamboo green thin sheets in a eutectic solvent solution for different times are shown. The changes in these elements reflect the changes in surface silicides, which to some extent explain the reasons for the changes in the mechanical properties of bamboo.

[0049] Figure 2 The change in porosity of bamboo flattened boards obtained after pre-treated bamboo strips have been softened by saturated steam and then flattened can provide a basis for subsequent resin filling and adhesive layer penetration.

[0050] Figure 3 , Figure 4 The changes in functional groups on the bamboo green side and bamboo yellow side of the high modulus modified thin bamboo green material prepared in Example 1 are shown respectively. It can be seen that the wax layer and lignin gradually decrease with the increase of treatment time.

[0051] Example 2

[0052] The method for preparing high-modulus modified thin bamboo greenwood and laminate in this embodiment includes the following steps:

[0053] S1. Remove the outer and inner nodes of the harvested raw bamboo, then longitudinally split it into bamboo strips. Remove the bamboo yellow but not the bamboo green from the bamboo strips, stack them at intervals, and dry them at 25°C for 24 hours to obtain pre-treated bamboo strips with a thickness of 6-7 mm.

[0054] A portion of the pretreated bamboo strips are placed in a steam tank and subjected to saturated steam softening treatment at a temperature of 160°C for 15 minutes to reach a softened and plastic state. After being taken out, they are flattened in a unfolding machine and then dried with hot air at a temperature of 60°C for 30 minutes. They are then bound with rigid straps or stacked with heavy objects to constrain them and prevent deformation, thus obtaining bamboo flattened boards.

[0055] S2. The pretreated bamboo strips and the bamboo flattening boards obtained in S1 are split along the tangential direction into pretreated bamboo green sheet with a thickness of 2 mm and bamboo flattening sheet with a thickness of 1.5 mm. Then, they are ultrasonically treated for 10 min at room temperature (24℃). The ultrasonic treatment frequency is 30KHz and the power is 180W to obtain ultrasonically treated bamboo green sheet and ultrasonically treated bamboo flattening sheet.

[0056] S3. Mix choline chloride (ChCl), glycerol (Gly), and aluminum chloride hexahydrate (AlCl3·6H2O) in a molar ratio of 1:2:0.05, and then stir at 100℃ for 30 min at a stirring speed of 100 rpm to obtain a transparent DES solvent composite solution.

[0057] The transparent DES solvent composite solution and deionized water are mixed in a volume ratio of 3:7 to obtain a eutectic solvent solution with a pH value of 6.

[0058] S4. The ultrasonically treated bamboo green sheet and the ultrasonically treated bamboo green sheet obtained in S2 were both immersed in the eutectic solvent solution obtained in S3 at a water bath temperature of 90℃ for 3 hours. After immersion, they were taken out and rinsed with distilled water until there was no eutectic solvent solution residue on the surface, and then air-dried for 10 hours to obtain the original high modulus modified thin bamboo green material and the flattened high modulus modified thin bamboo green material, respectively.

[0059] The eutectic solvent solution after impregnation can be recycled 1-5 times. When recycling, the impregnation time should be extended by 0.5 hours each time.

[0060] S5. Apply phenolic resin adhesive to the bamboo green side of one piece of the aforementioned high-modulus modified thin bamboo green material, and apply phenolic resin adhesive to the bamboo green side of another piece of the aforementioned high-modulus modified thin bamboo green material, with an adhesive application amount of 150g / m² for both pieces. 2Then, the material is hot-pressed and bonded using a hot press at a temperature of 120°C for 10 minutes and a pressure of 0.5 MPa to obtain a high-modulus modified thin bamboo laminate.

[0061] In this embodiment, S5, phenolic resin adhesive can be applied to the bamboo yellow side of one piece of high-modulus modified thin bamboo green material, and phenolic resin adhesive can be applied to the bamboo yellow side of another piece of high-modulus modified thin bamboo green material. The high-modulus modified thin bamboo green material laminate is prepared by hot pressing and bonding. The impregnation time in S4 can also be 1.5h, 2h, 2.5h, 2.7h, 3.5h, 4h, 4.5h or 4.8h.

[0062] Example 3

[0063] The method for preparing high-modulus modified thin bamboo greenwood and laminate in this embodiment includes the following steps:

[0064] S1. Remove the outer and inner nodes of the harvested raw bamboo, then longitudinally split it into bamboo strips. Remove the bamboo yellow but not the bamboo green from the bamboo strips, stack them at intervals, and dry them at 30°C for 24 hours to obtain pre-treated bamboo strips with a thickness of 6-7 mm.

[0065] A portion of the pretreated bamboo strips are placed in a steam tank and subjected to saturated steam softening treatment at a temperature of 180°C for 15 minutes to reach a softened and plastic state. After being taken out, they are flattened in a unfolding machine and then dried with hot air at a temperature of 60°C for 30 minutes. They are then bound with rigid straps or stacked with heavy objects to constrain them and prevent deformation, thus obtaining bamboo flattened boards.

[0066] S2. The pretreated bamboo strips and the bamboo flattening boards obtained in S1 are split along the tangential direction into pretreated bamboo green sheet with a thickness of 2 mm and bamboo flattening sheet with a thickness of 1.5 mm. Then, they are subjected to ultrasonic treatment for 15 min at room temperature (24℃). The frequency of ultrasonic treatment is 50KHz and the power is 400W. Ultrasonic bamboo green sheet and ultrasonic bamboo flattening sheet with green are obtained respectively.

[0067] S3. Mix choline chloride (ChCl), glycerol (Gly), and aluminum chloride hexahydrate (AlCl3·6H2O) in a molar ratio of 1:2:0.05, and then stir at 100℃ for 30 min at a stirring speed of 1000 rpm to obtain a transparent DES solvent composite solution.

[0068] The transparent DES solvent composite solution and deionized water are mixed in a volume ratio of 3:7 to obtain a eutectic solvent solution with a pH value of 7.

[0069] S4. The ultrasonically treated bamboo green sheet and the ultrasonically treated bamboo green sheet obtained in S2 were both immersed in the eutectic solvent solution obtained in S3 at a water bath temperature of 90℃ for 1 hour. After immersion, they were taken out and rinsed with distilled water until there was no eutectic solvent solution residue on the surface. Then they were freeze-dried at a temperature of -80℃ for 12 hours to obtain the original high modulus modified thin bamboo green material and the flattened high modulus modified thin bamboo green material, respectively.

[0070] The eutectic solvent solution after impregnation can be recycled 1-5 times. When recycling, the impregnation time should be extended by 0.5 hours each time.

[0071] S5. Apply isocyanate adhesive to the bamboo green side of one piece of the flattened high-modulus modified thin bamboo green material, and apply isocyanate adhesive to the bamboo yellow side of another piece of the flattened high-modulus modified thin bamboo green material. The amount of adhesive applied in both cases is 150 g / m². 2 Then, the material is hot-pressed and bonded using a hot press at a temperature of 140°C for 5 minutes and a pressure of 3MPa to obtain a flattened high-modulus modified thin bamboo laminate.

[0072] The flattened high-modulus modified thin bamboo laminate prepared in this embodiment has an elastic modulus of 10.85 GPa, a static bending strength of 215 MPa, and a bending toughness of 220 W. It is evident that the high-modulus modified thin bamboo laminate prepared in Example 1 has a higher modulus and better toughness, while the flattened high-modulus modified thin bamboo laminate prepared in this embodiment exhibits even better toughness.

[0073] In this embodiment S5, isocyanate adhesive can also be applied to the bamboo green side of one flattened high modulus modified thin bamboo green material, and isocyanate adhesive can also be applied to the bamboo green side of another flattened high modulus modified thin bamboo green material, and flattened high modulus modified thin bamboo green material laminate can be prepared by hot pressing; or isocyanate adhesive can be applied to the bamboo yellow side of one flattened high modulus modified thin bamboo green material, and isocyanate adhesive can also be applied to the bamboo yellow side of another flattened high modulus modified thin bamboo green material, and flattened high modulus modified thin bamboo green material laminate can be prepared by hot pressing.

[0074] The high-modulus modified thin bamboo plywood and the flattened high-modulus modified thin bamboo plywood prepared in Examples 1-3 can both be used as flooring, furniture materials, etc.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing high-modulus modified thin bamboo greenwood, characterized in that, The preparation method includes the following steps: S1. Remove the outer and inner nodes of the harvested raw bamboo, then longitudinally split it into bamboo strips. Remove the bamboo yellow but not the bamboo green from the bamboo strips, and then dry them to obtain pre-treated bamboo strips. A portion of the pretreated bamboo strips are then subjected to saturated steam softening treatment, flattened, and then dried with hot air to obtain flattened bamboo boards. S2. The pretreated bamboo strips obtained in S1 and the bamboo flattening board obtained in S1 are split along the tangential direction, and then ultrasonically treated at room temperature to obtain ultrasonically treated bamboo green sheet and ultrasonically treated bamboo flattening sheet with green. S3. Mix choline chloride, glycerol and aluminum chloride hexahydrate, and stir at a certain temperature to obtain a transparent DES solvent composite solution. The transparent DES solvent composite solution is mixed with deionized water to obtain a eutectic solvent solution; S4. The ultrasonically treated bamboo green sheet and the ultrasonically treated flattened bamboo green sheet obtained in S2 are both immersed in the eutectic solvent solution obtained in S3 under water bath conditions, so that the wax layer and SiO2 on the surface of the bamboo green react with the components in the eutectic solvent solution to form new silicides; after immersion, they are taken out, rinsed with distilled water, and then dried to obtain high modulus modified thin bamboo green material and flattened high modulus modified thin bamboo green material respectively. In S3, the molar ratio of choline chloride, glycerol, and aluminum chloride hexahydrate is 1:2:0.05; the mixture is stirred for 30 minutes at a temperature of 100°C at a stirring speed of 100-1000 rpm; and the volume ratio of the transparent DES solvent composite solution to deionized water is 3:

7. The temperature of the water bath in S4 is 60-90℃, and the immersion time is 1-5 hours.

2. The method for preparing high-modulus modified thin bamboo green material according to claim 1, characterized in that, The drying temperature in S1 is 25-30℃, and the drying time is 24h; the thickness of the pretreated bamboo strips is 6-7mm.

3. The method for preparing high-modulus modified thin bamboo green material according to claim 2, characterized in that, The saturated steam softening treatment in S1 is performed at a temperature of 160-180℃ for 15 minutes; the hot air drying is performed at a temperature of 60℃ for 30 minutes.

4. The method for preparing high-modulus modified thin bamboo green material according to claim 1, characterized in that, The ultrasonic treatment described in S2 has a frequency of 30-50KHz, a power of 180-400W, and a treatment time of 10-15min.

5. The method for preparing high-modulus modified thin bamboo green material according to claim 1, characterized in that, The drying described in S4 is either air drying or freeze drying. The air drying time is 8-12 hours, and the freeze drying temperature is -80℃ for 12 hours.

6. A method for preparing a laminate, characterized in that, The high-modulus modified thin bamboo green material is prepared using the preparation method described in any one of claims 1-5, wherein the method comprises the following steps: Adhesive is applied to either the green or yellow side of the two pieces of high-modulus modified thin bamboo green material, and then they are placed in a hot press for hot pressing and bonding to obtain a high-modulus modified thin bamboo green material laminate.

7. A method for preparing a laminate, characterized in that, A method for preparing laminates from flattened high-modulus modified thin bamboo veneer prepared by the preparation method according to any one of claims 1-5, characterized in that the method comprises the following steps: Adhesive is applied to either the bamboo green side or the bamboo yellow side of two pieces of flattened high modulus modified thin bamboo green material, and then they are placed in a hot press for hot pressing and bonding to obtain flattened high modulus modified thin bamboo green material laminate.

8. A method for preparing a laminate according to claim 6 or 7, characterized in that, The hot-press bonding temperature is 120-140℃, the time is 5-10 minutes, and the pressure is 0.5-3 MPa; the adhesive is a phenolic resin adhesive or an isocyanate adhesive, and the adhesive application amount is 150 g / m². 2 .

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