Environment-friendly sound-absorbing palm wood board and preparation method thereof

Abstract

The invention provides an environment-friendly sound-absorbing palm wood board and a preparation method thereof, and relates to the technical field of sound-absorbing materials. The board is mainly formed by compositing a first sound absorption layer and a second sound absorption layer. The first sound absorption layer is prepared from a low-density palm plate through perforation and delignification treatment, and the second sound absorption layer is prepared from a low-density palm plate through surface grooving treatment. Lignin and hemicellulose of wood cell walls are efficiently removed through an efficient and environment-friendly chemical modification method to form a cell porous structure, meanwhile, a multi-stage pore structure and a Helmholtz resonator space are constructed in cooperation with the physical processing technology of wood perforation and further surface grooving, and the porosity and sound absorption of wood are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of sound-absorbing materials, and in particular to an environmentally friendly sound-absorbing palm wood board and a preparation method thereof. Background Art

[0002] Traditional thermal insulation and sound-absorbing materials, mostly based on porous structures made from petroleum and minerals, present unsustainable, polluting, and difficult-to-degrade materials, and are increasingly subject to environmental regulations. Wood, a porous material, is widely used in furniture, interiors, and construction. To broaden wood's applications, the use of lightweight wood or wood fiber materials, as renewable, green wood sound-absorbing materials, to replace chemically synthesized materials like glass wool and mineral wool can reduce environmental pollution risks. Palm wood, due to its low density, abundant raw material resources, and low price, is an ideal wood sound-absorbing material. However, the wood's internal porosity is low, and the pores lack continuity and connectivity.

[0003] At present, wood sound-absorbing materials are achieved by increasing the porosity and pore continuity inside the material. Using microwave puffing treatment or mechanical drilling alone to increase the porosity cannot meet the sound absorption performance requirements. Composite polyester foam, glass fiber cotton, honeycomb aluminum and other sound-absorbing materials are needed, which increase the thickness and process complexity of the sound-absorbing board. The sound-absorbing material of artificial board-based perforated panels is mostly density fiberboard, which has a large amount of glue applied and may have problems such as formaldehyde pollution. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides an environmentally friendly sound-absorbing palm wood board and a preparation method thereof. It adopts an efficient and environmentally friendly chemical modification method to efficiently remove lignin and hemicellulose from the wood cell wall to form a cellular porous structure, thereby improving the porosity, connectivity and tortuosity characteristics inside the wood. At the same time, it cooperates with the physical processing of wood perforation and further surface grooving and multi-structure composite technology to construct a multi-level pore structure, realize the acoustic resonance damping effect, and significantly improve the porosity and sound absorption of the wood.

[0005] One of the purposes of the present invention is to provide an environmentally friendly sound-absorbing palm wood board.

[0006] A second object of the present invention is to provide a method for preparing the environmentally friendly sound-absorbing palm wood board.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0008] In a first aspect, the present invention provides an environmentally friendly sound-absorbing palm wood board, comprising a first sound-absorbing layer, wherein the first sound-absorbing layer is prepared by sequentially performing a perforation treatment and a delignification treatment on a palm wood board.

[0009] Furthermore, the environmentally friendly sound-absorbing palm wood board also includes a second sound-absorbing layer compounded with the first sound-absorbing layer, and the second sound-absorbing layer is prepared by surface-grooving the palm board.

[0010] The following details are provided:

[0011] First sound absorbing layer:

[0012] Palm board can be made from low-density waste palm wood by sawing or slicing. The density of palm board is 0.2-0.4g / cm 3 , thickness is 10-20mm.

[0013] The perforation process is to punch holes in the palm board to form through holes in the thickness direction.

[0014] In some embodiments, the diameter of the holes formed by the perforation process is 2-8 mm, and the perforation rate is 5-15% (the ratio of the horizontal hole area to the total area).

[0015] In some embodiments, the delignification process comprises the following steps:

[0016] The perforated palm board is immersed in a mixture of hydrogen peroxide and acetic acid, and a catalyst H2SO4 solution is added to perform delignification treatment to remove lignin and part of hemicellulose and form a porous structure; it is washed with running water, then immersed in an alcohol solution for ultrasonic treatment, and dried.

[0017] The hydrogen peroxide-acetic acid system selectively cleaves α-aryl ether bonds in lignin, achieving efficient lignin removal while retaining more cellulose and hemicellulose structures. This system avoids the toxicity and contamination of traditional strong acid / alkali processes, and its decomposition products are fully biodegradable, with low reagent costs and good recyclability.

[0018] Preferably, the mass concentration of hydrogen peroxide is 10%-30%, the mass concentration of acetic acid is 80%-99%, and the mass ratio of hydrogen peroxide to acetic acid is 1:1-1:1.3; the mass concentration of H2SO4 in the mixed solution is 0.2-0.5%;

[0019] Preferably, the temperature of the delignification treatment is 60-100° C., preferably 70, 80, or 90° C.; and the treatment time is 1-4 hours.

[0020] Preferably, the volume fraction of the alcohol solution is 95%-99%; the alcohol solution can be methanol, ethanol, tert-butanol, etc.

[0021] Preferably, the ultrasonic treatment frequency is 20-60 KHz, preferably 35, 45, 60 KHz, and the treatment temperature is room temperature;

[0022] Preferably, the drying temperature is 60-100°C, preferably 75, 85, or 90°C, and the drying time is 6-48 hours.

[0023] Ultrasonic-assisted alcohol solution treatment is used to better replace the water in the alcohol solution and the cell wall, prevent the rapid loss of water and collapse of the cell wall during the subsequent drying process, and maximize the maintenance of porosity and structural integrity.

[0024] Second sound absorbing layer:

[0025] Palm board can be made from low-density waste palm wood by sawing or slicing. The density of palm board is 0.2-0.4g / cm 3 , thickness is 10-20mm.

[0026] There is no particular restriction on the direction and shape of the surface grooves. The surface grooves can be single grooves along the length or width direction, or cross grooves. The cross-sectional shape of the grooves can be square grooves, semicircular grooves, or arc-shaped. The depth of the grooves is 3-5 mm, the width or diameter is 3-8 mm, and the spacing between adjacent grooves is 6-16 mm (the straight-line distance between the centers of adjacent grooves).

[0027] The second sound-absorbing layer formed by the surface grooving treatment is compounded with the first sound-absorbing layer to increase the longitudinal permeability of the pores and construct multi-level pores. At the same time, the perforated plate and the surface air groove plate are stacked to form a resonant damping structure for collaborative sound absorption (physical perforation and surface grooving technology, using the Helmholtz resonance principle to accelerate the dissipation of sound energy), thereby improving the sound absorption performance of the plate.

[0028] In a second aspect, the present invention provides a method for preparing the above-mentioned environmentally friendly sound-absorbing palm wood board, comprising the following steps:

[0029] The palm board is subjected to perforation treatment and delignification treatment in sequence to obtain a first sound absorbing layer.

[0030] Furthermore, the palm board is surface-grooved to obtain a second sound-absorbing layer, which is then combined with the first sound-absorbing layer to form a composite board.

[0031] Palm board can be made from low-density waste palm wood by sawing or slicing. The density of palm board is 0.2-0.4g / cm 3 , thickness is 10-20mm.

[0032] In some embodiments, the diameter of the holes formed by the perforation process is 2-8 mm, and the perforation rate is 5-15% (the ratio of the horizontal hole area to the total area).

[0033] In some embodiments, the delignification process comprises the following steps:

[0034] The perforated palm board is immersed in a mixture of hydrogen peroxide and acetic acid, and a catalyst H2SO4 solution is added to perform delignification treatment to remove lignin and part of hemicellulose and form a porous structure; it is washed with running water, then immersed in an alcohol solution for ultrasonic treatment, and dried.

[0035] The hydrogen peroxide-acetic acid system selectively cleaves α-aryl ether bonds in lignin, achieving efficient lignin removal while retaining more cellulose and hemicellulose structures. This system avoids the toxicity and contamination of traditional strong acid / alkali processes, and its decomposition products are fully biodegradable, with low reagent costs and good recyclability.

[0036] Preferably, the mass concentration of hydrogen peroxide is 10%-30%, the mass concentration of acetic acid is 80%-99%, and the mass ratio of hydrogen peroxide to acetic acid is 1:1-1:1.3; the mass concentration of H2SO4 in the mixed solution is 0.2-0.5%;

[0037] Preferably, the temperature of the delignification treatment is 60-100° C., preferably 70, 80, or 90° C.; and the treatment time is 1-4 hours.

[0038] Preferably, the volume fraction of the alcohol solution is 95%-99%; the alcohol solution can be methanol, ethanol, tert-butanol, etc.

[0039] Preferably, the ultrasonic treatment frequency is 20-60 KHz, preferably 35, 45, 60 KHz, and the treatment temperature is room temperature;

[0040] Preferably, the drying temperature is 60-100°C, preferably 75, 85, or 90°C, and the drying time is 6-48 hours.

[0041] In some embodiments, the grooves of the surface groove treatment have a depth of 3-5 mm, a width or diameter of 3-8 mm, and a spacing between adjacent grooves of 6-16 mm (straight-line distance between adjacent groove centers).

[0042] In some specific embodiments, the method for preparing the environmentally friendly sound-absorbing palm wood board comprises the following steps:

[0043] Preparation of palm wood boards - board perforation processing - delignification treatment with hydrogen peroxide / acetic acid solution - water immersion cleaning treatment - ultrasonic-assisted alcohol solvent impregnation treatment - high-temperature rapid drying - surface groove board composite.

[0044] (1) Preparation of palm wood board: select the density of 0.2-0.4g / cm 3 Waste palm wood is prepared into boards with a thickness of 5-20 mm by sawing or slicing, and dried to a moisture content of 8-15%;

[0045] (2) Plate perforation treatment: The plate is perforated with a hole diameter of 2-8 mm and a perforation rate of 5-15%;

[0046] (3) Hydrogen peroxide-acetic acid delignification treatment: The perforated board is immersed in a mixture of hydrogen peroxide and acetic acid with a mass concentration ratio of 1:1-1:1.3, H2SO4 catalyst is added, and the board is treated at 60-100 °C for 1-4 hours to remove lignin and hemicellulose and form a porous structure;

[0047] (4) Solvent removal treatment: After the treatment is completed, the board is removed from the delignification solution and immediately placed in a large amount of running deionized water for washing. The washing time is not less than 30 minutes. During this period, the wood blocks are constantly stirred to ensure that the chemical waste is completely removed until the pH value of the wood reaches 7;

[0048] (5) Alcohol solution replacement treatment: The washed palm wood is immersed in a 95%-99% alcohol solution and treated in ultrasound to replace the moisture inside the wood;

[0049] (6) Rapid drying: Raise the temperature to 70±3°C within 1 hour, and stop drying when the moisture content reaches below 12% and the temperature drops below 40°C;

[0050] (7) Surface grooved board composite: Take another palm wood board and perform surface groove processing to obtain a grooved sound-absorbing backboard. The grooved sound-absorbing backboard is composited on the back of the palm wood board through an environmentally friendly adhesive to form a double-layer sound-absorbing structure. The adhesive used is a soybean-based adhesive or a polyurethane adhesive.

[0051] The present invention uses low-density palm wood, which is abundant in raw materials and inexpensive, as raw material, and drills holes on the surface before chemical treatment, thereby improving the permeability and contact area of the delignification solution, thereby achieving uniform and efficient lignin removal. The hydrogen peroxide and acetic acid solution system used selectively cracks the α-aryl ether bonds in the lignin, and the addition of catalysts such as H2SO4 achieves efficient lignin removal while retaining more cellulose and hemicellulose structures. The system avoids the toxic pollution of traditional strong acid / alkali processes, and its decomposition products are completely biodegradable, and the reagent cost is low and the recyclability is good. Ultrasonic waves are used to assist in solvent exchange with a low-surface-tension alcohol solution, which prevents the wood pores from collapsing due to fiber keratinization and hydrogen bonding during normal pressure drying, successfully retaining the original hierarchical cellulose fiber structure of the wood, ensuring the high porosity of the material while maintaining good mechanical strength, and solving the problem that traditional preparation methods destroy the wood structure and lead to a decrease in mechanical properties.

[0052] This method uses a chemical delignification process, using a hydrogen peroxide and acetic acid solution with a catalyst such as H2SO4 to efficiently remove lignin. This process, combined with perforation technology, creates multi-level cellular pores. Ultrasonic-assisted alcohol solution dehydration replaces moisture in the wood cell walls. Grooves are machined into the surface of palm wood to create a composite backboard, increasing the vertical penetration of pores and further creating multi-level pores, thereby improving the board's sound absorption performance. This method is primarily suitable for the manufacture of interior decoration and architectural sound-absorbing panels.

[0053] Beneficial effects:

[0054] 1. After the board is pre-treated by perforation, the hydrogen peroxide / acetic acid solution system removes the lignin and hemicellulose from the board in a directionally and efficiently manner.

[0055] 2. Ultrasonic wave assisted solvent exchange with low surface tension alcohol solution was used to prevent the collapse of wood pores due to fiber keratinization and hydrogen bonding during normal pressure drying, successfully retaining the original hierarchical cellulose fiber structure of the wood. This not only ensured the high porosity of the material but also maintained good mechanical strength, solving the problem of traditional preparation methods destroying the wood structure and leading to a decline in mechanical properties.

[0056] 3. The perforated delignified sound-absorbing surface plate is combined with the grooved sound-absorbing surface plate, and the composite interface between the surface plate and the bottom plate forms air groove damping holes to increase the loss of sound energy.

[0057] 4. The present invention creatively combines chemical delignification with physical perforation and surface grooving technology. Chemical delignification increases the porosity, connectivity, and tortuosity of the wood's internal pores by removing lignin and some hemicellulose from the wood cell walls, thereby extending the sound wave propagation path, increasing its friction time with the pore wall, and enhancing the efficiency of sound energy conversion. Physical perforation and surface grooving technology utilizes the Helmholtz resonance principle and, through resonant structure design, stacks the perforated plate with the surface air groove plate to form a resonant structure for synergistic sound absorption, significantly improving sound absorption, especially in the high-frequency band (1500-2000Hz), where the sound absorption effect is more obvious. Therefore, through perforation and chemical treatment, a multi-level pore structure of palm wood is constructed, increasing the porosity, connectivity, and tortuosity of the wood, achieving a first synergistic sound absorption effect of different pores. Further, by stacking the perforated plate with the surface groove plate bottom plate, a second synergistic effect of air resonance is achieved, greatly improving the porosity and sound absorption of the wood while maintaining mechanical strength.

[0058] The present invention has been described in detail above, but the above embodiments are merely illustrative in nature and are not intended to limit the present invention. In addition, the present invention is not limited by any theory described in the above prior art or invention summary or the following examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1This is a schematic structural diagram of the environmentally friendly sound-absorbing palm wood board of the present invention. DETAILED DESCRIPTION

[0060] The present invention will be further described below with reference to the examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed in the present invention.

[0061] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, and methods in the art.

[0062] Example 1

[0063] The density is selected to be 0.2-0.4g / cm 3 Waste palm wood is sawn or sliced into 1000mm x 150mm x 10mm thick boards. The boards are stacked and dried in a drying kiln at 80°C to a moisture content of 12%. Wood drilling equipment is used to perforate the dried boards, with a diameter of 2mm and a perforation rate of 8%.

[0064] A mixture of 20% hydrogen peroxide and 80% acetic acid at a mass ratio of 1:1.1 was poured into an electrically heated water tank containing a fixed drilled plate and heated immediately. A 0.4% H₂SO₄ catalyst was added, and the wood was delignified at 90°C for 3 hours. After treatment, the wood was removed from the delignification solution and immediately rinsed in a large volume of running deionized water for at least 30 minutes, stirring the wood constantly to ensure complete removal of chemical waste. The rinsed palm wood was then immersed in a 90% ethanol solution and dehydrated with ultrasonication to displace moisture from the wood. The delignified wood was then dried in a kiln, heating to 70±3°C over 1 hour. Drying was completed when the moisture content dropped below 12% and the temperature dropped below 40°C, completing the first sound-absorbing layer.

[0065] Example 2

[0066] The density is selected to be 0.2-0.4g / cm 3 Waste palm wood is sawn or sliced into 1000mm x 150mm x 10mm thick boards. The boards are stacked and dried in a kiln at 80°C to a moisture content of 12%. Wood drilling equipment is used to perforate the dried boards, with a diameter of 2mm and a perforation rate of 8%.

[0067] A mixture of 20% hydrogen peroxide and 80% acetic acid at a mass ratio of 1:1.1 was poured into an electrically heated water tank containing a fixed drilled plate and heated immediately. A 0.2% H₂SO₄ catalyst was added, and the wood was delignified at 75°C for 1.5 hours. After treatment, the wood was removed from the delignification solution and immediately rinsed in a large volume of running deionized water for at least 30 minutes, stirring the wood constantly to ensure complete removal of the chemical wastewater. The rinsed palm wood was then immersed in a 90% ethanol solution and dehydrated with ultrasonic assistance to displace the moisture within the wood. The delignified wood was then dried in a kiln, heating to 70±3°C over 1 hour. Drying was completed when the moisture content dropped below 12% and the temperature dropped below 40°C, completing the first sound-absorbing layer.

[0068] Another dried palm wood board was taken and grooved on the surface. The grooves were arranged in a vertical cross-groove pattern. The cross-sectional shape of the grooves was a square with a depth of 3 mm and a width of 3 mm. The groove spacing was 10 mm to obtain a second sound absorbing layer backboard.

[0069] The first sound-absorbing layer and the second sound-absorbing layer are bonded and compounded using polyurethane adhesive to complete the production of the double-layer sound-absorbing structure palm board.

[0070] Example 3

[0071] The density is selected to be 0.2-0.4g / cm 3 Waste palm wood is sawn or sliced into 1000mm x 150mm x 10mm thick boards. The boards are stacked and dried in a kiln at 80°C to a moisture content of 12%. Wood drilling equipment is used to perforate the dried boards, with holes of 4mm in diameter and a perforation rate of 14%.

[0072] A 20% concentration of hydrogen peroxide and an 80% concentration of acetic acid were mixed in a mass ratio of 1:1.1. The mixture was then poured into an electrically heated water bath containing a fixed drilled plate and heated. A 0.2% H₂SO₄ catalyst was added, and the wood was delignified at 75°C for 1.5 hours. After treatment, the wood was removed from the delignification solution and immediately rinsed in a large volume of running deionized water for at least 30 minutes, with constant stirring to ensure complete removal of chemical waste. The rinsed palm wood was then immersed in a 90% ethanol solution and dehydrated with ultrasonication to displace moisture from the wood. The delignified wood was then dried in a kiln, heating to 70±3°C over 1 hour. Drying was completed when the moisture content dropped below 12% and the temperature dropped below 40°C, completing the first sound-absorbing layer.

[0073] Another dried palm wood board was taken and grooved on the surface. The grooves were arranged in a vertical cross-groove pattern. The cross-section of the grooves was a rectangle with a depth of 5 mm and a width of 5 mm. The groove spacing was 10 mm to obtain the second sound absorbing layer backboard.

[0074] The first sound-absorbing layer and the second sound-absorbing layer are bonded and compounded using polyurethane adhesive to complete the production of the double-layer sound-absorbing structure palm board.

[0075] Example 4

[0076] The density is selected to be 0.2-0.4g / cm 3 Waste palm wood is sawn or sliced into 1000mm x 150mm x 10mm thick boards. The boards are stacked and dried in a kiln at 80°C to a moisture content of 12%. Wood drilling equipment is used to perforate the dried boards, with holes of 4mm in diameter and a perforation rate of 14%.

[0077] A mixture of 20% hydrogen peroxide and 80% acetic acid at a mass ratio of 1:1.1 is poured into an electrically heated water tank containing a fixed drilled plate. A 0.4% H₂SO₄ catalyst or additive is added, and the plate is delignified at 75°C for 3 hours. After treatment, the plate is removed from the delignification solution and immediately rinsed in a large volume of running deionized water for at least 30 minutes, stirring the wood constantly to ensure complete removal of chemical waste. The rinsed palm wood is then immersed in a 90% ethanol solution and dehydrated with ultrasonication to displace moisture from the wood. The delignified plate is then dried in a kiln, heating to 70±3°C over 1 hour. Drying is completed when the moisture content drops below 12% and the temperature drops below 40°C, completing the first sound-absorbing layer.

[0078] Another dried palm wood board was taken and grooved on the surface. The grooves were arranged in a vertical cross-groove pattern. The cross-section of the grooves was a rectangle with a depth of 5 mm and a width of 5 mm. The groove spacing was 10 mm to obtain the second sound absorbing layer backboard.

[0079] The first sound-absorbing layer and the second sound-absorbing layer are bonded and compounded using polyurethane adhesive to complete the production of the double-layer sound-absorbing structure palm board.

[0080] Example 5

[0081] The density is selected to be 0.2-0.4g / cm 3 Waste palm wood is sawn or sliced into 1000mm x 150mm x 10mm thick boards. The boards are stacked and dried in a kiln at 80°C to a moisture content of 12%. Wood drilling equipment is used to perforate the dried boards, with holes of 4mm in diameter and a perforation rate of 14%.

[0082] A mixture of 20% hydrogen peroxide and 80% acetic acid at a mass ratio of 1:1.1 is poured into an electrically heated water tank containing a fixed drilled plate. A 0.4% H₂SO₄ catalyst or additive is added, and the wood is delignified at 90°C for 3 hours. After treatment, the wood is removed from the delignification solution and immediately rinsed in a large volume of running deionized water for at least 30 minutes, stirring the wood to ensure complete removal of chemical waste. The rinsed palm wood is then immersed in a 90% ethanol solution and dehydrated with ultrasonication to displace moisture from the wood. The delignified wood is then dried in a kiln, heating to 70±3°C over 1 hour. Drying is completed when the moisture content drops below 12% and the temperature drops below 40°C, completing the first sound-absorbing layer.

[0083] Another dried palm wood board was taken and grooved on the surface. The grooves were arranged in a vertical cross-groove pattern. The cross-section of the grooves was a rectangle with a depth of 5 mm and a width of 5 mm. The groove spacing was 10 mm to obtain the second sound absorbing layer backboard.

[0084] The first sound-absorbing layer and the second sound-absorbing layer are bonded and compounded using polyurethane adhesive to complete the production of the double-layer sound-absorbing structure palm board.

[0085] Example 6

[0086] The density is selected to be 0.2-0.4g / cm 3 Waste palm wood is sawn or sliced into 1000mm x 150mm x 10mm thick boards. The boards are stacked and dried in a kiln at 80°C to a moisture content of 12%. Wood drilling equipment is used to perforate the dried boards, with holes of 4mm in diameter and a perforation rate of 14%.

[0087] A mixture of 30% hydrogen peroxide and 80% acetic acid at a mass ratio of 1:1.1 is poured into an electrically heated water tank containing a fixed drilled plate. A 0.5% H₂SO₄ catalyst or additive is added, and the plate is delignified at 95°C for 3 hours. After treatment, the plate is removed from the delignification solution and immediately rinsed in a large volume of running deionized water for at least 30 minutes, stirring the wood to ensure complete removal of chemical waste. The rinsed palm wood is then immersed in a 90% ethanol solution and dehydrated with ultrasonication to displace moisture from the wood. The delignified plate is then dried in a kiln, heating to 70±3°C over 1 hour. Drying is completed when the moisture content drops below 12% and the temperature drops below 40°C, completing the first sound-absorbing layer.

[0088] Another dried palm wood board was taken and grooved on the surface. The grooves were arranged in a vertical cross-groove pattern. The cross-section of the grooves was a rectangle with a depth of 5 mm and a width of 5 mm. The groove spacing was 10 mm to obtain the second sound absorbing layer backboard.

[0089] The first sound-absorbing layer and the second sound-absorbing layer are bonded and compounded using polyurethane adhesive to complete the production of the double-layer sound-absorbing structure palm board.

[0090] Comparative Example 1

[0091] The density is selected to be 0.2-0.4g / cm 3 The discarded palm wood is prepared into 1000mm×150mm×10mm thick boards by sawing or slicing. The boards are stacked and placed in a drying kiln at a temperature of 80°C to dry to a moisture content of 12%, completing the production of the first sound-absorbing layer.

[0092] The first sound-absorbing layer and the second sound-absorbing layer without surface groove treatment are bonded and compounded using polyurethane adhesive to complete the production of the double-layer sound-absorbing structure palm board.

[0093] Comparative Example 2

[0094] The density is selected to be 0.2-0.4g / cm 3 Waste palm wood is sawn or sliced into 1000mm x 150mm x 10mm thick boards. The boards are stacked and dried in a kiln at 80°C to a moisture content of 12%. Wood drilling equipment is used to perforate the dried boards, with holes of 4mm in diameter and a perforation rate of 14%, completing the first sound-absorbing layer.

[0095] The first sound-absorbing layer and the second sound-absorbing layer without surface groove treatment are bonded and compounded using polyurethane adhesive to complete the production of the double-layer sound-absorbing structure palm board.

[0096] Comparative Example 3

[0097] The density is selected to be 0.2-0.4g / cm 3 The waste palm wood is prepared into 1000mm×150mm×10mm thick boards by sawing or slicing. The boards are stacked and placed in a drying kiln at a temperature of 80℃ to dry to a moisture content of 12%.

[0098] A mixture of 20% hydrogen peroxide and 80% acetic acid at a mass ratio of 1:1.1 is poured into an electrically heated water tank containing a fixed drilled plate. A 0.4% H₂SO₄ catalyst or additive is added, and the wood is delignified at 90°C for 3 hours. After treatment, the wood is removed from the delignification solution and immediately rinsed in a large volume of running deionized water for at least 30 minutes, stirring the wood to ensure complete removal of chemical waste. The rinsed palm wood is then immersed in a 90% ethanol solution and dehydrated with ultrasonication to displace moisture from the wood. The delignified wood is then dried in a kiln, heating to 70±3°C over 1 hour. Drying is completed when the moisture content drops below 12% and the temperature drops below 40°C, completing the first sound-absorbing layer.

[0099] The first sound-absorbing layer and the second sound-absorbing layer without surface groove treatment are bonded and compounded using polyurethane adhesive to complete the production of the double-layer sound-absorbing structure palm board.

[0100] Comparative Example 4

[0101] The density is selected to be 0.2-0.4g / cm 3 Waste palm wood is sawn or sliced into 1000mm x 150mm x 10mm thick boards. The boards are stacked and dried in a kiln at 80°C to a moisture content of 12%. Wood drilling equipment is used to perforate the dried boards, with holes of 4mm in diameter and a perforation rate of 14%.

[0102] Another dried palm wood board was taken and grooved on the surface. The grooves were arranged in a vertical cross-groove pattern. The cross-section of the grooves was a rectangle with a depth of 5 mm and a width of 5 mm. The groove spacing was 10 mm to obtain the second sound absorbing layer backboard.

[0103] The first sound-absorbing layer and the second sound-absorbing layer are bonded and compounded using polyurethane adhesive to complete the production of the double-layer sound-absorbing structure palm board.

[0104] Comparative Example 5

[0105] The density is selected to be 0.2-0.4g / cm 3 The waste palm wood is prepared into 1000mm×150mm×10mm thick boards by sawing or slicing. The boards are stacked and placed in a drying kiln at a temperature of 80℃ to dry to a moisture content of 12%.

[0106] A mixture of 20% hydrogen peroxide and 80% acetic acid at a mass ratio of 1:1.1 is poured into an electrically heated water tank containing a fixed drilled plate. A 0.4% H₂SO₄ catalyst or additive is added, and the wood is delignified at 90°C for 3 hours. After treatment, the wood is removed from the delignification solution and immediately rinsed in a large volume of running deionized water for at least 30 minutes, stirring the wood to ensure complete removal of chemical waste. The rinsed palm wood is then immersed in a 90% ethanol solution and dehydrated with ultrasonication to displace moisture from the wood. The delignified wood is then dried in a kiln, heating to 70±3°C over 1 hour. Drying is completed when the moisture content drops below 12% and the temperature drops below 40°C, completing the first sound-absorbing layer.

[0107] Another dried palm wood board was taken and grooved on the surface. The grooves were arranged in a vertical cross-groove pattern. The cross-section of the grooves was a rectangle with a depth of 5 mm and a width of 5 mm. The groove spacing was 10 mm to obtain the second sound absorbing layer backboard.

[0108] The first sound-absorbing layer and the second sound-absorbing layer are bonded and compounded using polyurethane adhesive to complete the production of the double-layer sound-absorbing structure palm board.

[0109] Comparative Example 6

[0110] The density is selected to be 0.2-0.4g / cm 3 Waste palm wood is sawn or sliced into 1000mm x 150mm x 10mm thick boards. The boards are stacked and dried in a kiln at 80°C to a moisture content of 12%. Wood drilling equipment is used to perforate the dried boards, with holes of 4mm in diameter and a perforation rate of 14%.

[0111] A mixture of 20% hydrogen peroxide and 80% acetic acid is prepared in a mass ratio of 1:1.1. The mixture is then poured into an electrically heated water tank over a fixed drilled plate and heated. A 0.4% H₂SO₄ catalyst or additive is added, and the plate is delignified at 90°C for 3 hours. After treatment, the plate is removed from the delignification solution and immediately rinsed in a large volume of running deionized water for at least 30 minutes, stirring the wood to ensure complete removal of chemical waste. The rinse cycle continues until the pH reaches 7. The delignified plate is then dried in a kiln, heating to 70±3°C over 1 hour. Drying is completed when the moisture content drops below 12% and the temperature drops below 40°C, completing the first sound-absorbing layer.

[0112] Another dried palm wood board was taken and grooved on the surface. The grooves were arranged in a vertical cross-groove pattern. The cross-section of the grooves was a rectangle with a depth of 5 mm and a width of 5 mm. The groove spacing was 10 mm to obtain the second sound absorbing layer backboard.

[0113] The first sound-absorbing layer and the second sound-absorbing layer are bonded and compounded using polyurethane adhesive to complete the production of the double-layer sound-absorbing structure palm board.

[0114] Test process:

[0115] Test method:

[0116] 1. The sound absorption coefficient of palm board is tested according to GB / T18696.2-2002 "Measurement of sound absorption coefficient and acoustic impedance in acoustic impedance tubes Part 2: Transfer function method".

[0117] The results are shown in Table 1.

[0118] Table 1

[0119]

[0120] 2. The compressive elastic modulus and compressive strength of the palm board sound absorption specimens were tested according to GB / T1927.11-2022 "Test methods for physical and mechanical properties of small defect-free wood specimens Part 11: Determination of compressive strength parallel to the grain". The results are shown in Table 2.

[0121] Table 2

[0122]

[0123]

[0124] The above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced with equivalents, without departing from the spirit and substance of the claims of the present invention; and such modifications or replacements remain within the scope of the claims of the present invention.

Claims

1. An environmentally friendly sound-absorbing palm wood board, characterized in that: The invention comprises a first sound absorbing layer, wherein the first sound absorbing layer is prepared by sequentially performing perforation treatment and delignification treatment on a palm board.

2. The environmentally friendly sound-absorbing palm wood board according to claim 1, characterized in that: The environmentally friendly sound-absorbing palm wood board further comprises a second sound-absorbing layer compounded with the first sound-absorbing layer, wherein the second sound-absorbing layer is prepared by surface-grooving a palm board.

3. The environmentally friendly sound-absorbing palm wood board according to claim 1, characterized in that: The diameter of the holes formed by the perforation process is 2-8 mm, and the perforation rate is 5-15%.

4. The environmentally friendly sound-absorbing palm wood board according to claim 1, characterized in that: The delignification process includes the following steps: The perforated palm board was immersed in a mixture of hydrogen peroxide and acetic acid, and a catalyst H2SO4 solution was added to perform delignification treatment to remove lignin and part of hemicellulose and form a porous structure; it was washed with running water, then immersed in an alcohol solution for ultrasonic treatment and dried; Preferably, the mass concentration of hydrogen peroxide is 10% to 30%, the mass concentration of acetic acid is 80% to 99%, and the mass ratio of hydrogen peroxide to acetic acid is 1:1-1:1.3; the mass concentration of H2SO4 in the mixed solution is 0.2 to 0.5%; Preferably, the delignification treatment temperature is 60-100° C., and the treatment time is 1-4 hours.

5. The environmentally friendly sound-absorbing palm wood board according to claim 1, characterized in that: The depth of the grooves formed by the surface grooving treatment is 3 to 5 mm, the width or diameter is 3 to 8 mm, and the spacing between adjacent grooves is 6 to 16 mm.

6. A method for preparing the environmentally friendly sound-absorbing palm wood board according to any one of claims 1 to 5, characterized in that: The following steps are involved: The palm board is subjected to perforation treatment and delignification treatment in sequence to obtain a first sound absorbing layer.

7. The preparation method according to claim 6, characterized in that The diameter of the holes formed by the perforation process is 2-8 mm, and the perforation rate is 5-15%.

8. The preparation method according to claim 6, characterized in that The delignification process includes the following steps: The perforated palm wood was immersed in a mixture of hydrogen peroxide and acetic acid, and a catalyst H2SO4 solution was added to perform delignification treatment to remove lignin and some hemicellulose and form a multi-level pore interconnected structure; the palm wood was washed with running water, then immersed in an alcohol solution for ultrasonic treatment and dried; Preferably, the mass concentration of hydrogen peroxide is 10% to 30%, the mass concentration of acetic acid is 80% to 99%, and the mass ratio of hydrogen peroxide to acetic acid is 1:1-1:1.3; the mass concentration of H2SO4 in the mixed solution is 0.2 to 0.5%; Preferably, the delignification treatment temperature is 60-100° C., and the treatment time is 1-4 hours.

9. The preparation method according to claim 6, characterized in that The method further comprises the following steps: performing surface grooving treatment on the palm board to obtain a second sound absorbing layer, which is combined with the first sound absorbing layer to form a composite board.

10. The preparation method according to claim 9, characterized in that The depth of the grooves formed by the surface grooving treatment is 3 to 5 mm, the width or diameter is 3 to 8 mm, and the spacing between adjacent grooves is 6 to 16 mm.

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