Bamboo-based functional composite board as well as preparation method and application thereof

Abstract

The invention relates to the field of noise control, in particular to a bamboo-based functional composite board and a preparation method and application thereof. The bamboo-based functional composite board comprises a super-hydrophobic recombined bamboo layer, a foamed aluminum layer, a honeycomb aluminum foil layer, a rhombic aluminum mesh layer, a corrugated aluminum foil layer and a recombined bamboo substrate layer which are sequentially stacked from top to bottom, the outer surface of the super-hydrophobic recombined bamboo layer is of a micro-nano structure, and the static water contact angle of the super-hydrophobic recombined bamboo layer is larger than 150 degrees. And the structure of the foamed aluminum layer is an array formed by a plurality of inverted trapezoidal cavity units. According to the bamboo-based functional composite board, through organic combination of the bamboo-based composite material and the sound insulation material, noise transmission is effectively reduced, and meanwhile the stability and durability of the structure are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of noise control, and more particularly to a bamboo-based functional composite board, its preparation method, and its application. Background Technology

[0002] With the acceleration of urbanization and the continuous increase in urban population density, the efficiency of urban space utilization and the quality of life for residents have become urgent issues to be addressed. In recent years, outdoor activities such as square dancing have become widely popular in cities, becoming one of the important ways for residents to relax and enjoy themselves. However, the loud noise and dynamic rhythms generated by these activities cause serious noise pollution to surrounding residents, especially in places that require a quiet environment (such as libraries and hospitals). Noise not only affects residents' normal lives and rest, but may also have long-term negative impacts on people's physical and mental health. Therefore, solving the noise problem is an important issue facing urban interior spaces today.

[0003] Traditional soundproofing measures, such as simple sound barriers or green belts, often fail to achieve satisfactory results and cannot balance aesthetics and practicality. Sound barriers are typically made of metal or plastic, resulting in a monotonous appearance, poor integration with the surrounding environment, and a tendency to cause visual pollution. Furthermore, the high density of metal or plastic materials leads to heavy noise-proofing structures, resulting in high installation and transportation costs and making it difficult to achieve mobile assembly. While green belts offer some soundproofing, their soundproofing performance is limited and requires significant land resources and long-term maintenance.

[0004] Bamboo, as a green material, boasts rapid growth, high strength and toughness, and strong renewability, making it an ideal environmentally friendly material. Bamboo has a short growth cycle, allowing for rapid propagation, and its fibrous structure endows it with excellent mechanical properties and weather resistance. In particular, highly weather-resistant bamboo panels (such as reconstituted bamboo) are not only strong and corrosion-resistant but also possess a pleasant appearance, blending seamlessly with park landscapes, making them an ideal choice for manufacturing outdoor noise-reducing materials. Despite these numerous advantages, bamboo still faces some challenges in its application to noise-reduction materials. For example, bamboo's sound insulation performance is limited, requiring combination with other materials to achieve the desired soundproofing effect.

[0005] Therefore, developing a bamboo-based material with excellent noise reduction effect is of great significance. Summary of the Invention

[0006] This invention provides a bamboo-based functional composite board, its preparation method, and its application. The bamboo-based functional composite board combines the high strength, toughness, environmental performance, and aesthetics of bamboo with the lightweight and sound insulation properties of aluminum foil honeycomb paper, forming a high-efficiency, environmentally friendly, and structurally stable composite material.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: This invention provides a bamboo-based functional composite board, comprising, from top to bottom, a superhydrophobic reconstituted bamboo layer, a foamed aluminum layer, a honeycomb aluminum foil layer, a diamond-shaped aluminum mesh layer, a corrugated aluminum foil layer, and a reconstituted bamboo substrate layer stacked sequentially. The outer surface of the superhydrophobic reconstituted bamboo layer has a micro-nano structure, and the static water contact angle of the superhydrophobic reconstituted bamboo layer is >150°. The structure of the aluminum foam layer is an array composed of multiple inverted trapezoidal cavity units.

[0008] In some specific embodiments, the superhydrophobic reconstituted bamboo layer includes a first bamboo fiber veneer, a second bamboo fiber veneer, a wood veneer, a third bamboo fiber veneer, and a fourth bamboo fiber veneer stacked sequentially. The substrate of the first bamboo fiber veneer, the second bamboo fiber veneer, the third bamboo fiber veneer and the fourth bamboo fiber veneer is epoxy resin impregnated reconstituted bamboo; the grain direction of the wood veneer is perpendicular to the grain direction of the second bamboo fiber veneer and the third bamboo fiber veneer. The density of the superhydrophobic reconstituted bamboo is ≥1 g / cm³. 3 ; The micro / nano structure is formed by processing nano-SiO2 and fluorinated silane; The superhydrophobic reconstituted bamboo layer also has pores, the diameter of which is 2-5 mm and the spacing between which is 60-120 mm.

[0009] In some specific embodiments, the aluminum foam layer further includes polyurethane viscoelastic colloid filling the gaps between the inverted trapezoidal cavity units; the loss factor of the polyurethane viscoelastic colloid is ≥0.3; In the aluminum foam layer, the open porosity of the aluminum foam is ≥90%, the porosity of the aluminum foam is 70%~80%, and the material of the aluminum foam is an Al-Mg-Si alloy, wherein the mass percentage of magnesium in the Al-Mg-Si alloy is 1%~3%. The inverted trapezoidal cavity unit has an angle of 40~50° and a base side length of 5~8mm. The honeycomb aluminum foil layer includes 3003 aluminum alloy foil. The pore size of the honeycomb is 5-8 mm. Holes with a pore size of 1-1.5 mm are provided on the wall surface of the honeycomb. The porosity of the honeycomb wall surface is 3%-5%. An oxide film with a thickness of 10-20 μm is provided on both the inner and outer sides of the honeycomb wall surface.

[0010] In some specific embodiments, the aluminum foil in the corrugated aluminum foil layer includes 1060 aluminum; the wavelength of the corrugations in the corrugated aluminum foil layer is 3~5mm, and the wave height of the corrugations in the corrugated aluminum foil layer is 1~2mm; The reconstituted bamboo substrate layer is formed by longitudinally oriented bamboo fibers; the longitudinal orientation deviation of the bamboo fibers is ≤5°.

[0011] In some specific embodiments, the thickness ratio of the superhydrophobic reconstituted bamboo layer, the foamed aluminum layer, the honeycomb aluminum foil layer, the diamond-shaped aluminum mesh layer, the corrugated aluminum foil layer, and the reconstituted bamboo substrate layer is 1.5~2:2.5~3:2~2.2:0.6~0.8:0.5~0.7:2~2.2.

[0012] A second aspect of the present invention also provides a method for preparing the above-mentioned bamboo-based functional composite board, characterized by comprising the following steps: A superhydrophobic reconstituted bamboo layer, a foamed aluminum layer, a honeycomb aluminum foil layer, a diamond-shaped aluminum mesh layer, a corrugated aluminum foil layer, and a reconstituted bamboo substrate are sequentially stacked, with a first adhesive applied between each layer, and then subjected to a first hot pressing to obtain a bamboo-based functional composite board.

[0013] In some specific embodiments, the coating amount of the first adhesive is 80~125g / m². 2 ; The conditions for the first hot pressing are: temperature 140~160℃, time 20min, and pressure 1.2~1.5MPa.

[0014] In some specific embodiments, the method for preparing the superhydrophobic reconstituted bamboo layer includes the following steps: The first bamboo fiber veneer, the second bamboo fiber veneer, the wood veneer, the third bamboo fiber veneer and the fourth bamboo fiber veneer are stacked in sequence, and a second adhesive is applied between each layer. Then, a second hot pressing is performed to obtain a bamboo substrate. The bamboo substrate was treated with nano-SiO2 and fluorinated silane to form a micro-nano structure on the surface of the bamboo substrate; then an opening process was performed. The conditions for the second hot pressing are: temperature 140~150℃, time 30min, and pressure 1.2~1.5MPa; In some specific embodiments, the preparation method of the first bamboo fiber veneer, the second bamboo fiber veneer, the third bamboo fiber veneer, and the fourth bamboo fiber veneer includes the following steps: (1) Soak the bamboo strips in a sodium hydroxide solution to obtain pretreated bamboo strips; (2) The pretreated bamboo strips are rolled and loosened to obtain transversely interconnected, longitudinally long bundles of fibrous bamboo fibers; (3) The bamboo bundle fiber is woven with cotton thread using a weaving machine to obtain a whole sheet of bamboo bundle fiber; (4) The whole bamboo bundle fiber is immersed in an epoxy resin solution and dried after immersion to obtain the impregnated bamboo bundle fiber. (5) The impregnated bamboo fiber bundles are impregnated again in an epoxy resin solution, and dried after impregnation to obtain bamboo fiber veneer; In step (1), the thickness of the bamboo strip is 5~7mm, and the moisture content of the bamboo strip is ≥65%; In step (1), the bamboo strips include bamboo strips of moso bamboo on the side closest to the green bamboo; In step (1), the concentration of sodium hydroxide is 2wt%~7wt%, the soaking temperature is 10~30℃, and the soaking time is 12~24h; In step (2), the compaction pressure is 5~20MPa; In step (2), the thickness of the bamboo fiber bundle is 3~5mm; In step (4), the solid content of the epoxy resin solution is 15wt%~22wt%, the impregnation temperature is 10~30℃, and the impregnation time is 20~30min.

[0015] In step (5), the solid content of the epoxy resin solution is 15wt%~22wt%, the impregnation temperature is 10~30℃, and the impregnation time is 15~20min.

[0016] A third aspect of the present invention also provides an application of the above-mentioned bamboo-based functional composite board in noise isolation in outdoor locations.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) High-efficiency sound insulation: The composite structure of bamboo strand veneer and aluminum foil honeycomb paper can effectively absorb and reflect noise, reducing noise transmission. The unique inverted trapezoidal cavity foam aluminum coupled with the honeycomb aluminum foil layer comprehensively utilizes the triple mechanism of Helmholtz resonance, impedance gradient matching and viscous dissipation to significantly extend the lower limit of the effective sound absorption frequency band to about 100Hz, effectively making up for the lack of control over low-frequency noise (such as square dance music) by traditional materials. The micro-nano structure and regular pores of the superhydrophobic reconstituted bamboo layer further increase the acoustic roughness and form a parallel resonator with the lower structure, synergistically improving the mid-to-high frequency sound absorption efficiency and overall sound insulation.

[0018] (2) Lightweight: The low density of bamboo fiber veneer, aluminum foam and aluminum foil honeycomb paper makes the composite board lightweight, easy to install and transport, and suitable for mobile assembly.

[0019] (3) Good durability: Bamboo fiber veneer is specially treated and has good waterproof, moisture-proof and corrosion-resistant properties, and has a long service life.

[0020] (4) Beautiful and practical: The natural texture and color of bamboo give the composite board a beautiful appearance, which can be perfectly integrated with the park landscape and enhance the overall landscape effect.

[0021] (5) Excellent environmental performance: Bamboo is a renewable resource with low energy consumption during processing, which meets environmental protection requirements.

[0022] (6) The composite structure of bamboo-based functional composite board solves the problem of bamboo (expansion coefficient ≈ 25 × 10) -6 (°C) and metals (expansion coefficient ≈ 23 × 10) -6 / ℃) thermal deformation mismatch. Foamed aluminum is used in conjunction with an inverted trapezoidal cavity acoustic trap, with a high-strength reconstituted bamboo substrate (10-15mm) as the lower support layer. This retains the acoustic advantages of honeycomb paper while protecting it from environmental corrosion with foamed aluminum. Attached Figure Description

[0023] The above and other objects, features, and advantages of the invention will be apparent from the following description of preferred embodiments illustrating the gist of the invention and its use, and the accompanying drawings, in which: Figure 1 This is a schematic diagram of the structure of the bamboo-based functional composite board in this invention.

[0024] Figure 2 The figures show the performance of the embodiments and Comparative Example 1.

[0025] Figure 3 The figures show the performance of the embodiments and Comparative Example 1. Detailed Implementation

[0026] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments described below are for illustrative purposes only and do not limit the scope of the invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the following embodiments, conditions and methods known in the art can be used for processing.

[0027] This invention provides a bamboo-based functional composite board, comprising, from top to bottom, a superhydrophobic reconstituted bamboo layer, a foamed aluminum layer, a honeycomb aluminum foil layer, a diamond-shaped aluminum mesh layer, a corrugated aluminum foil layer, and a reconstituted bamboo substrate layer stacked sequentially. The outer surface of the superhydrophobic reconstituted bamboo layer has a micro-nano structure, and the static water contact angle of the superhydrophobic reconstituted bamboo layer is >150°. The structure of the aluminum foam layer is an array composed of multiple inverted trapezoidal cavity units.

[0028] In this invention, "the outer surface of the superhydrophobic reconstituted bamboo layer" refers to the side of the superhydrophobic reconstituted bamboo layer that is far away from the aluminum foam layer.

[0029] In this invention, "inverted trapezoid" refers to a trapezoid with its longer base closer to the superhydrophobic reconstituted bamboo layer and its shorter base closer to the honeycomb aluminum foil layer.

[0030] In this invention, a micro-nano structure is formed on the outer surface of the superhydrophobic reconstituted bamboo layer, thereby making the static water contact angle of the outer surface of the superhydrophobic reconstituted bamboo layer >150°. The micro-nano structure increases the actual surface area of ​​the material in contact with air, increases the acoustic roughness of the surface, improves the low-frequency sound absorption performance, and broadens the sound absorption frequency band.

[0031] In some embodiments, the superhydrophobic reconstituted bamboo layer includes a first bamboo fiber veneer, a second bamboo fiber veneer, a wood veneer, a third bamboo fiber veneer, and a fourth bamboo fiber veneer stacked sequentially.

[0032] In some embodiments, the first bamboo fiber veneer, the second bamboo fiber veneer, the wood veneer, the third bamboo fiber veneer, and the fourth bamboo fiber veneer have the same thickness.

[0033] In some embodiments, the wood veneer includes poplar veneer or eucalyptus veneer.

[0034] In some embodiments, the substrate of the first bamboo fiber veneer, the second bamboo fiber veneer, the third bamboo fiber veneer and the fourth bamboo fiber veneer is epoxy resin impregnated reconstituted bamboo.

[0035] In some embodiments, the grain direction of the wood veneer is perpendicular to the grain direction of the second bamboo fiber veneer and the third bamboo fiber veneer.

[0036] In this invention, the superhydrophobic reconstituted bamboo layer is preferably composed of layers with interlaced textures.

[0037] In some embodiments, the density of the superhydrophobic reconstituted bamboo is ≥1 g / cm³. 3 As an example, the density of superhydrophobic reconstituted bamboo can be 1 g / cm³. 3 1.2g / cm 3 1.5g / cm 3 2g / cm 3 3g / cm 3 4g / cm 3 and 5g / cm 3 wait.

[0038] In some embodiments, the micro / nano structure is formed by processing nano-SiO2 and fluorinated silane.

[0039] In some embodiments, the superhydrophobic reconstituted bamboo layer further comprises pores, the diameter of which is 2-5 mm and the spacing between the pores is 60-120 mm. For example, the diameter of the pores can be 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, and 5 mm, and the spacing between the pores can be 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, and 120 mm, etc.

[0040] In this invention, pores are provided in the superhydrophobic reconstituted bamboo layer, which allows the superhydrophobic reconstituted bamboo layer to combine with the foam aluminum layer, precisely enhancing low-frequency sound absorption and improving the sound absorption efficiency of the target frequency band.

[0041] In some embodiments, the aluminum foam layer further includes polyurethane viscoelastic colloid filling the gaps between the inverted trapezoidal cavity units.

[0042] In this invention, the amount of polyurethane viscoelastic colloid filled is not specifically limited, as long as the array structure composed of multiple inverted trapezoidal cavity units in the aluminum foam layer is firm.

[0043] In some embodiments, the loss factor of the polyurethane viscoelastic colloid is ≥0.3. In this invention, the loss factor of the polyurethane viscoelastic colloid refers to that at room temperature (25°C).

[0044] In some embodiments, the open porosity of the aluminum foam layer is ≥90%, and the porosity of the aluminum foam layer is 70%~80%. For example, the open porosity of the aluminum foam layer can be 90%, 91%, 93%, 95%, 98%, and 100%, etc., and the porosity of the aluminum foam layer can be 70%, 72%, 75%, 77%, 79%, and 80%, etc.

[0045] In some embodiments, the foamed aluminum is made of an Al-Mg-Si alloy, wherein the mass percentage of magnesium in the Al-Mg-Si alloy is 1% to 3%. As an example, the mass percentage of magnesium in the Al-Mg-Si alloy can be 1%, 1.5%, 2%, 2.5%, and 3%, etc.

[0046] In some embodiments, the inverted trapezoidal cavity unit has an angle of 40-50° and a base side length of 5-8 mm. In this invention, the thickness of the inverted trapezoidal cavity is not specifically limited; the base side length of the inverted trapezoidal cavity unit refers to the shorter side length of the inverted trapezoid.

[0047] In some embodiments, the aluminum foil in the honeycomb aluminum foil layer includes 3003 aluminum alloy foil.

[0048] In some embodiments, the honeycomb aluminum foil layer has a pore size of 5-8 mm, and the honeycomb wall surface has holes with a pore size of 1-1.5 mm. The porosity of the honeycomb wall surface is 3%-5%, and an oxide film is provided on both the inner and outer sides of the honeycomb wall surface, with a thickness of 10-20 μm.

[0049] In this invention, the formation of the oxide film includes the following steps: First, the honeycomb aluminum foil undergoes multi-stage ultrasonic cleaning and fine alkaline etching with 40-60wt% NaOH to ensure absolute cleanliness of the complex pore inner walls. Then, a mixed electrolyte solution of 120-160 g / L sulfuric acid and 10-15 g / L oxalic acid at a volume ratio of 1:1 is used. The electrolyte is applied at a low temperature of 15-20℃ using a pulsed power supply with an average current density of 1.0-1.5 A / dm³. 2 The process involves combining a bidirectional forced circulation system to ensure effective exchange of the oxide solution within the deep pores, thereby forming a uniform oxide film of approximately 10-15 μm on all surfaces. Subsequently, the pores are sealed with medium-temperature nickel salts and immediately rinsed with boiling water and dried.

[0050] In this invention, the use of medium-temperature nickel salt sealing refers to the nanoscale micropores of the oxide film itself. When aluminum is anodized in acidic electrolytes such as sulfuric acid, a ceramic film is formed by the close stacking of countless hexagonal prism-shaped alumina cells. At the center of each cell, a micropore with a diameter of nanometers (usually 10-30 nanometers) is naturally formed perpendicular to the surface during the growth process.

[0051] In some embodiments, the corrugated aluminum foil layer comprises 1060 aluminum, the wavelength of the corrugations is 3-5 mm, and the wave height is 1-2 mm. In this invention... Figure 1 The corrugation pattern in the corrugated aluminum foil layer is not shown in the figure.

[0052] In some embodiments, the reconstituted bamboo substrate layer is formed by longitudinally oriented bamboo fibers; the longitudinal orientation deviation of the bamboo fibers in the bamboo substrate bearing layer is ≤5°.

[0053] In some specific embodiments, the thickness ratio of the superhydrophobic reconstituted bamboo layer, the foamed aluminum layer, the honeycomb aluminum foil layer, the diamond-shaped aluminum mesh layer, the corrugated aluminum foil layer, and the reconstituted bamboo substrate layer is 1.5~2:2.5~3:2~2.2:0.6~0.8:0.5~0.7:2~2.2.

[0054] A second aspect of the present invention also provides a method for preparing the above-mentioned bamboo-based functional composite board, comprising the following steps: A superhydrophobic reconstituted bamboo layer, a foamed aluminum layer, a honeycomb aluminum foil layer, a diamond-shaped aluminum mesh layer, a corrugated aluminum foil layer, and a reconstituted bamboo substrate are sequentially stacked, with a first adhesive applied between each layer, and then subjected to a first hot pressing to obtain a bamboo-based functional composite board.

[0055] In this invention, the first adhesive is not specifically limited, and any adhesive commonly used in the art can be selected. In some embodiments, the first adhesive may be an epoxy resin.

[0056] In some embodiments, the conditions for the first hot pressing are: temperature of 140~160℃, time of 20min, and pressure of 1.2~1.5MPa.

[0057] In some embodiments, the coating amount of the first adhesive is 80~125 g / m². 2 In this invention, the amount of the first adhesive applied refers to the amount applied between each layer.

[0058] In some embodiments, the method for preparing the superhydrophobic reconstituted bamboo layer includes the following steps: The first bamboo fiber veneer, the second bamboo fiber veneer, the wood veneer, the third bamboo fiber veneer and the fourth bamboo fiber veneer are stacked in sequence, and a second adhesive is applied between each layer. Then, a second hot pressing is performed to obtain a bamboo substrate. The bamboo substrate was treated with nano-SiO2 and fluorinated silane to form micro-nano structures on the surface of the bamboo substrate; then, an opening process was performed.

[0059] In this invention, the second adhesive is not specifically limited, and any adhesive commonly used in the art can be used. In some embodiments, the second adhesive may be an epoxy resin.

[0060] In some embodiments, the amount of the second adhesive applied is 80~125 g / m². 2 In this invention, the amount of the first adhesive applied refers to the amount applied between each layer.

[0061] In some embodiments, the conditions for the second hot pressing are: temperature of 140~150℃, time of 30min, and pressure of 1.2~1.5MPa.

[0062] In some embodiments, the specific process of treating the bamboo substrate with nano-SiO2 and fluorinated silane includes the following steps: The bamboo substrate is cleaned and dried, and then activated by plasma to obtain the treated bamboo substrate. The treated bamboo substrate was placed in a nano-SiO2 ethanol suspension with a solid content of 1wt%~5wt%, and after loading the particles by the dip-coating method, it was pre-cured at 80~100℃ for 10~20min to obtain a bamboo substrate loaded with SiO2. Fluorosilane was added to an acidic ethanol solution and hydrolyzed to obtain a modified solution. The bamboo substrate loaded with SiO2 was immersed in the modified solution, and the immersed bamboo substrate was heat-treated at 120~150℃ for 1~2 hours.

[0063] In some embodiments, the amount of fluorinated silane added is 1 wt% to 3 wt%, based on the total mass of the fluorinated silane and the acidic ethanol solution.

[0064] In some embodiments, fluorinated silanes include heptadecafluorodecyltrimethoxysilane (FAS-17), tridecafluorooctyltriethoxysilane (FAS-13), and perfluoroalkyl ethyl acrylate copolymer silane derivatives.

[0065] In this invention, the purpose of the activation treatment is to enhance the surface activity of the substrate and strengthen the adhesion between the subsequent functional layer and the substrate.

[0066] In this invention, pre-curing allows nano-SiO2 to initially adhere, creating micron-nano-level physical roughness on the bamboo surface.

[0067] In this invention, the silanol groups (-SiOH) generated after the hydrolysis of fluorinated silane undergo dehydration condensation with the hydroxyl groups on the surface of bamboo and nano-SiO2 to form a strong Si-O-Si covalent network. During the heat treatment process, the chemical anchoring of nano-SiO2 and the directional arrangement of the low surface energy layer of fluorocarbon chains are completed simultaneously, so that the contact angle of the bamboo surface is greater than 150°, and a durable superhydrophobic micro-nano bamboo substrate with a lotus leaf-like effect and stable structure is obtained.

[0068] In some embodiments, the preparation method of the first bamboo fiber veneer, the second bamboo fiber veneer, the third bamboo fiber veneer, and the fourth bamboo fiber veneer includes the following steps: (1) Soak the bamboo strips in a sodium hydroxide solution to obtain pretreated bamboo strips; (2) The pretreated bamboo strips are rolled and loosened to obtain transversely interconnected, longitudinally long bundles of fibrous bamboo fibers; (3) The bamboo bundle fiber is woven with cotton thread using a weaving machine to obtain a whole sheet of bamboo bundle fiber; (4) The whole bamboo bundle fiber is immersed in an epoxy resin solution and dried after immersion to obtain the impregnated bamboo bundle fiber. (5) The bamboo bundle fibers after impregnation are impregnated again in epoxy resin solution, and dried after impregnation to obtain bamboo fiber veneer.

[0069] In this invention, the method for preparing the fiber veneer refers to the fact that the first bamboo fiber veneer, the second bamboo fiber veneer, the third bamboo fiber veneer, and the fourth bamboo fiber veneer are all prepared using the above-described method.

[0070] In some embodiments, in step (1), the concentration of sodium hydroxide is 2wt%~7wt%, the soaking temperature is 10~30℃, and the soaking time is 12~24h. In this invention, soaking bamboo strips in sodium hydroxide solution can remove some lignin, thereby improving the uniformity of disintegration and obtaining denser, more disintegrated bamboo fiber bundles. The pretreated bamboo strips are easier to further refine and disintegrate.

[0071] In some embodiments, in step (2), the rolling pressure is 5~20MPa.

[0072] In some embodiments, in step (2), the thickness of the bamboo bundle fibers is 3-5 mm. In this invention, by crushing and loosening, the thin-walled cells of bamboo are detached, forming a more uniform fiber structure.

[0073] In this invention, weaving bamboo bundle fibers with cotton thread helps to enhance the connectivity between fibers and improve the convenience of subsequent processing.

[0074] In some embodiments, in step (4), the solid content of the epoxy resin solution is 15wt%~22wt%, the impregnation temperature is 10~30℃, and the impregnation time is 20~30min.

[0075] In this invention, by impregnating the bamboo bundles with phenolic resin, the bonding force between the bamboo fibers is enhanced due to the excellent adhesive properties and water resistance of the epoxy resin.

[0076] In this invention, the drying conditions in step (4) are not specifically limited; conventional methods in the art can be used to dry the bamboo fibers until the moisture content is ≤8wt%. In some embodiments, drying can be carried out in a dryer or by sun drying. The dried bamboo fiber has a low moisture content, which is beneficial for subsequent processing and improving product stability.

[0077] In some embodiments, in step (5), the solid content of the epoxy resin solution is 15wt%~22wt%, the impregnation temperature is 10~30℃, and the impregnation time is 15~20min. In this invention, impregnation again in epoxy resin can further enhance the durability and modulus of the surface bamboo bundles.

[0078] In this invention, the drying conditions in step (5) are not specifically limited; conventional methods in the art can be used to dry the bamboo fibers until the moisture content is ≤8wt%. In some embodiments, drying can be carried out in a dryer or by sun drying. The dried bamboo fiber bundles have a low moisture content, which is beneficial for subsequent processing and improving product stability.

[0079] A third aspect of the present invention also provides an application of the above-mentioned bamboo-based functional composite board in noise isolation in outdoor locations.

[0080] In some embodiments, the method of application includes: The bamboo-based functional composite board is installed on a triangular frame to form a stable support structure; the triangular frame is made of thin bamboo fiber / wood veneer layered composite material. The tilt direction and tilt angle of the above structure are adjusted by means of tie rod structure or snap gear structure to ensure that high frequency sound is refracted and reflected into the air by the noise reduction structure and does not propagate laterally. Some low frequency noise is repeatedly dissipated through the small holes on the plate in the aluminum foil honeycomb paper structure. The aforementioned modular structures are assembled using metal connectors to form a herringbone-shaped covered walkway. One side of the herringbone shape is a noise-damping panel, while the other side can be a glass structure for light transmission or a structure with columns and seating. The herringbone-shaped noise-damping covered walkway is assembled using modular technology. Each module is 1.5-2.2m long, 3-5m high, with an adjustable slope of 100-150 degrees, and a width of 2-3m.

[0081] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. The embodiments of this application are only examples, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0082] Preparation Example 1 The preparation of superhydrophobic reconstituted bamboo layers includes the following steps: (1) A bamboo strip with a thickness of 6 mm and a moisture content of 70% on the green side of the bamboo was soaked in a sodium hydroxide solution with a concentration of 5 wt% at 25°C for 24 h to obtain a pretreated bamboo strip. (2) The pretreated bamboo strips are rolled and loosened at 10MPa to obtain bamboo bundle fibers with a thickness of 4mm that are interconnected laterally and long longitudinally; the bamboo bundle fibers are woven with cotton thread through a weaving machine to obtain a whole sheet of bamboo bundle fibers. (3) Bamboo fiber bundles were immersed in an epoxy resin solution with a solid content of 18wt% for 25 minutes at 25°C, with an immersion amount of 20wt%. After immersion, the moisture content after drying was 7wt%. Then, the bundles were immersed in an epoxy resin solution with a solid content of 18wt% for 18 minutes at 25°C, with an immersion amount of 20wt%. After immersion, the moisture content after drying was 6wt%, and bamboo fiber veneer was obtained. (4) Assemble the above-mentioned bamboo fiber veneer by alternating layers of 2 layers of bamboo fiber veneer, 1 layer of poplar veneer, and 2 layers of bamboo fiber veneer (each layer having the same thickness), and coat each layer with epoxy resin (the amount of epoxy resin coated between each layer is 100g / m²). 2 The sample was hot-pressed at 145℃ and 1MPa for 30 minutes to obtain a thickness of 6mm and a density of 1.05g / cm³. 3 Reconstituted bamboo boards; (5) The bamboo substrate is cleaned and dried, and then activated by plasma to obtain the treated bamboo substrate. The treated bamboo substrate is placed in a nano-SiO2 ethanol suspension with a solid content of 4wt%, and after loading the particles by the dip-coating method, it is pre-cured at 90℃ for 20min to obtain a bamboo substrate loaded with SiO2. Fluorosilane is added to an acidic ethanol solution (based on the total mass of fluorosilane and acidic ethanol solution, the amount of fluorosilane added is 2wt%), and a modified solution is obtained by hydrolysis. The bamboo substrate loaded with SiO2 is immersed in the modified solution, and the immersed bamboo substrate is heat-treated at 130℃ for 2h to obtain a micro-nano structure formed on the surface of the bamboo substrate. Then, drilling is performed to obtain a superhydrophobic reconstituted bamboo layer. The diameter of the holes on the superhydrophobic reconstituted bamboo layer is 2mm, and the spacing of the holes is 60mm.

[0083] Preparation Example 2 The preparation of superhydrophobic reconstituted bamboo layers includes the following steps: (1) Bamboo strips with a thickness of 7 mm and a moisture content of 68 wt% on the green side were soaked in a sodium hydroxide solution with a concentration of 2 wt% at 25°C for 18 h to obtain pretreated bamboo strips. (2) The pretreated bamboo strips are rolled and loosened at 10MPa to obtain bamboo bundle fibers with a thickness of 5mm that are interconnected laterally and long longitudinally; the bamboo bundle fibers are woven with cotton thread through a weaving machine to obtain a whole sheet of bamboo bundle fibers. (3) Bamboo fiber bundles were immersed in an epoxy resin solution with a solid content of 20wt% at 25°C for 20min. After immersion, the moisture content was 7wt% after drying. Then, the bundles were immersed in an epoxy resin solution with a solid content of 18wt% at 25°C for 20min. After immersion, the moisture content was 6wt% after drying, and bamboo fiber veneer was obtained. (4) Assemble the above-mentioned bamboo fiber veneer by combining 2 layers of bamboo fiber veneer, 1 layer of poplar veneer, and 2 layers of bamboo fiber veneer (each layer has the same thickness), with the texture of each layer being crisscrossed. Coat each layer with epoxy resin (the amount of epoxy resin coated between each layer is 100g / m²). 2 The sample was hot-pressed at 145℃ and 1MPa for 30 minutes to obtain a thickness of 6mm and a density of 1.05g / cm³. 3 Reconstituted bamboo boards; (5) The bamboo substrate is cleaned and dried, and then activated by plasma to obtain the treated bamboo substrate. The treated bamboo substrate is placed in a nano-SiO2 ethanol suspension with a solid content of 4wt%, and after loading the particles by the dip-coating method, it is pre-cured at 90°C for 15min to obtain a bamboo substrate loaded with SiO2. Fluorosilane is added to an acidic ethanol solution (based on the total mass of fluorosilane and acidic ethanol solution, the amount of fluorosilane added is 1.5wt%), and a modified solution is obtained by hydrolysis. The bamboo substrate loaded with SiO2 is immersed in the modified solution, and the immersed bamboo substrate is heat-treated at 130°C for 2h to obtain a micro-nano structure formed on the surface of the bamboo substrate. Then, drilling is performed to obtain a superhydrophobic reconstituted bamboo layer. The diameter of the holes on the superhydrophobic reconstituted bamboo layer is 3mm, and the spacing of the holes is 80mm.

[0084] Example 1 The bamboo-based functional composite board includes, from top to bottom, the superhydrophobic reconstituted bamboo layer, the foamed aluminum layer, the honeycomb aluminum foil layer, the diamond-shaped aluminum mesh layer, the corrugated aluminum foil layer, and the reconstituted bamboo substrate layer prepared in Preparation Example 1. The thickness ratio of the superhydrophobic reconstituted bamboo layer, the foamed aluminum layer, the honeycomb aluminum foil layer, the diamond-shaped aluminum mesh layer, the corrugated aluminum foil layer, and the reconstituted bamboo substrate layer is 1.5:3:2:0.8:0.7:2. The aluminum foam layer is formed by an array of multiple inverted trapezoidal cavity units formed by aluminum foam and polyurethane viscoelastic colloid filling the gaps between the inverted trapezoidal units. The loss factor of the polyurethane viscoelastic colloid is 0.3. The open porosity of the aluminum foam is 90%, the porosity of the aluminum foam is 75%, the material of the aluminum foam is an Al-Mg-Si alloy with a magnesium mass percentage of 2%, the inclination angle of the inverted trapezoidal cavity unit is 45°, and the side length of the bottom surface of the inverted trapezoidal cavity unit is 6mm. In the honeycomb aluminum foil layer, the aluminum foil is 3003 aluminum alloy foil, the honeycomb pore size is 6mm, and there are holes on the honeycomb wall with a pore size of 1mm, resulting in a porosity of 4%. An oxide film with a thickness of 15μm is formed on both the inner and outer sides of the honeycomb wall. The oxide film formation process involves: firstly, multi-stage ultrasonic cleaning and fine alkaline etching with 50wt% NaOH to ensure absolute cleanliness of the complex pore inner walls; then, a mixed electrolyte of 140g / L sulfuric acid solution and 12g / L oxalic acid solution at a volume ratio of 1:1 is used, and the mixture is applied at a low temperature of 15℃ using a pulsed power supply (average current density 1.2 A / dm³). 2 It is combined with a two-way forced circulation system to ensure effective exchange of the oxide solution in the deep hole, thereby forming a uniform oxide film on the wall surface; then, medium-temperature nickel salt is used to seal the hole, and boiling water rinsing and thorough drying are performed immediately. In the corrugated aluminum foil layer, the aluminum foil is 1060 aluminum; the wavelength of the corrugations in the corrugated aluminum foil layer is 4mm, and the wave height of the corrugations in the corrugated aluminum foil layer is 1mm; The reconstituted bamboo substrate layer is formed by longitudinally oriented bamboo fibers.

[0085] The preparation of bamboo-based functional composite boards includes the following steps: An epoxy resin adhesive is applied between the superhydrophobic reconstituted bamboo layer, the aluminum foam layer, the honeycomb aluminum foil layer, the diamond-shaped aluminum mesh layer, the corrugated aluminum foil layer, and the reconstituted bamboo substrate (the coating amount of epoxy resin between each layer is 100g / m²). 2 Then, it is hot-pressed at 150℃ and 1.5MPa for 20 minutes to obtain bamboo-based functional composite board.

[0086] Example 2 The difference from Example 1 is that the superhydrophobic reconstituted bamboo layer obtained in Example 1 is replaced with that obtained in Example 2.

[0087] Comparative Example 1 The perforated bamboo engineered wood board is made of three layers of 5mm bamboo engineered wood arranged in a crisscross pattern. It is hot-pressed at 145°C for 30 minutes, resulting in a thickness of 15mm. The board surface is uniformly perforated with a hole diameter of 3mm and a hole spacing of 90mm.

[0088] Performance testing The following performance tests were performed on Example 1, Example 2, and Comparative Example 1 respectively: According to the American standard ASTM E2611-2009, "Standard Test Method for Measuring Vertical Incident Transmission in Acoustic Materials Based on Transmission Matrix Method," a four-channel circular impedance tube (SW422, Beijing Shengwang Acoustic & Electrical Technology Co., Ltd., China) was used for testing. The specimens were circular with diameters of 30 mm and 100 mm. To avoid gaps caused by manufacturing errors affecting the test results, the outer edge of the material was wrapped with PTFE tape before being placed inside the tube. In acoustic analysis, analyzing the sound insulation performance of the material at each frequency individually is not practical. To analyze the differences in sound insulation performance of the material at different frequency bands, the entire frequency domain is often divided into several smaller frequency bands or frequency paths. Commonly used division methods include 1 / 3 octave band and 1 / 1 octave band, and the energy is uniform within each octave band. After obtaining the transmission loss spectrum, the spectrum was divided using 1 / 3 octave bands. The results are as follows: Figure 2 and Figure 3 As shown.

[0089] Depend on Figure 2 and Figure 3 It can be seen that, compared with perforated bamboo engineered wood panels, bamboo-based functional composite panels have significantly higher sound insulation performance, indicating better sound insulation properties. In terms of sound absorption, the sound absorption coefficient of bamboo-based functional composite panels is higher than that of perforated bamboo engineered wood panels in the 500-3150Hz range, resulting in superior overall sound absorption performance.

Claims

1. A bamboo-based functional composite board, characterized in that, It includes, from top to bottom, a superhydrophobic reconstituted bamboo layer, a foamed aluminum layer, a honeycomb aluminum foil layer, a diamond-shaped aluminum mesh layer, a corrugated aluminum foil layer, and a reconstituted bamboo substrate layer; The outer surface of the superhydrophobic reconstituted bamboo layer has a micro-nano structure, and the static water contact angle of the superhydrophobic reconstituted bamboo layer is >150°. The structure of the aluminum foam layer is an array composed of multiple inverted trapezoidal cavity units.

2. The bamboo-based functional composite board according to claim 1, characterized in that, The superhydrophobic reconstituted bamboo layer includes a first bamboo fiber veneer, a second bamboo fiber veneer, a wood veneer, a third bamboo fiber veneer, and a fourth bamboo fiber veneer stacked in sequence. The substrate of the first bamboo fiber veneer, the second bamboo fiber veneer, the third bamboo fiber veneer and the fourth bamboo fiber veneer is epoxy resin impregnated reconstituted bamboo; the grain direction of the wood veneer is perpendicular to the grain direction of the second bamboo fiber veneer and the third bamboo fiber veneer. The density of the superhydrophobic reconstituted bamboo is ≥1 g / cm³. 3 ; The micro / nano structure is formed by processing nano-SiO2 and fluorinated silane; The superhydrophobic reconstituted bamboo layer also has pores, the diameter of which is 2-5 mm and the spacing between which is 60-120 mm.

3. The bamboo-based functional composite board according to claim 1, characterized in that, The aluminum foam layer also includes polyurethane viscoelastic colloid filling the gaps between the inverted trapezoidal cavity units; the loss factor of the polyurethane viscoelastic colloid is ≥0.3; In the aluminum foam layer, the open porosity of the aluminum foam is ≥90%, the porosity of the aluminum foam is 70%~80%, and the material of the aluminum foam is an Al-Mg-Si alloy, wherein the mass percentage of magnesium in the Al-Mg-Si alloy is 1%~3%. The inverted trapezoidal cavity unit has an angle of 40~50° and a base side length of 5~8mm. The honeycomb aluminum foil layer includes 3003 aluminum alloy foil. The pore size of the honeycomb is 5-8 mm. Holes with a pore size of 1-1.5 mm are provided on the wall surface of the honeycomb. The porosity of the honeycomb wall surface is 3%-5%. An oxide film with a thickness of 10-20 μm is provided on both the inner and outer sides of the honeycomb wall surface.

4. The bamboo-based functional composite board according to claim 1, characterized in that, The corrugated aluminum foil layer contains 1060 aluminum, the wavelength of the corrugations is 3~5mm, and the wave height of the corrugations is 1~2mm. The reconstituted bamboo substrate layer is formed by longitudinally oriented bamboo fibers; the longitudinal orientation deviation of the bamboo fibers is ≤5°.

5. The bamboo-based functional composite board according to claim 1, characterized in that, The thickness ratio of the superhydrophobic reconstituted bamboo layer, foamed aluminum layer, honeycomb aluminum foil layer, diamond-shaped aluminum mesh layer, corrugated aluminum foil layer and reconstituted bamboo substrate layer is 1.5~2:2.5~3:2~2.2:0.6~0.8:0.5~0.7:2~2.

2.

6. A method for preparing a bamboo-based functional composite board according to any one of claims 1 to 5, characterized in that, Includes the following steps: A superhydrophobic reconstituted bamboo layer, a foamed aluminum layer, a honeycomb aluminum foil layer, a diamond-shaped aluminum mesh layer, a corrugated aluminum foil layer, and a reconstituted bamboo substrate are sequentially stacked, with a first adhesive applied between each layer, and then subjected to a first hot pressing to obtain a bamboo-based functional composite board.

7. The method for preparing the bamboo-based functional composite board according to claim 6, characterized in that, The coating amount of the first adhesive is 80~125g / m². 2 ; The conditions for the first hot pressing are: temperature 140~160℃, time 20min, and pressure 1.2~1.5MPa.

8. The method for preparing the bamboo-based functional composite board according to claim 6, characterized in that, The method for preparing the superhydrophobic reconstituted bamboo layer includes the following steps: The first bamboo fiber veneer, the second bamboo fiber veneer, the wood veneer, the third bamboo fiber veneer and the fourth bamboo fiber veneer are stacked in sequence, and a second adhesive is applied between each layer. Then, a second hot pressing is performed to obtain a bamboo substrate. The bamboo substrate is treated with nano-SiO2 and fluorinated silane to form a micro-nano structure on the surface of the bamboo substrate; then an opening process is performed. The conditions for the second hot pressing are: temperature 140~150℃, time 30min, and pressure 1.2~1.5MPa.

9. The method for preparing the bamboo-based functional composite board according to claim 8, characterized in that, The preparation method of the first bamboo fiber veneer, the second bamboo fiber veneer, the third bamboo fiber veneer, and the fourth bamboo fiber veneer includes the following steps: (1) Soak the bamboo strips in a sodium hydroxide solution to obtain pretreated bamboo strips; (2) The pretreated bamboo strips are rolled and loosened to obtain transversely interconnected, longitudinally long bundles of fibrous bamboo fibers; (3) The bamboo bundle fiber is woven with cotton thread using a weaving machine to obtain a whole sheet of bamboo bundle fiber; (4) The whole bamboo bundle fiber is immersed in an epoxy resin solution and dried after immersion to obtain the impregnated bamboo bundle fiber. (5) The impregnated bamboo fiber bundles are impregnated again in an epoxy resin solution, and dried after impregnation to obtain bamboo fiber veneer; In step (1), the thickness of the bamboo strip is 5~7mm, and the moisture content of the bamboo strip is ≥65%; In step (1), the bamboo strips include bamboo strips of moso bamboo on the side closest to the green bamboo; In step (1), the concentration of sodium hydroxide is 2wt%~7wt%, the soaking temperature is 10~30℃, and the soaking time is 12~24h; In step (2), the compaction pressure is 5~20MPa; In step (2), the thickness of the bamboo fiber bundle is 3~5mm; In step (4), the solid content of the epoxy resin solution is 15wt%~22wt%, the impregnation temperature is 10~30℃, and the impregnation time is 20~30min. In step (5), the solid content of the epoxy resin solution is 15wt%~22wt%, the impregnation temperature is 10~30℃, and the impregnation time is 15~20min.

10. The application of the bamboo-based functional composite board according to any one of claims 1 to 5 in noise isolation in outdoor locations.

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