Environment-friendly moisture-resistant wood core diatom plate and preparation method thereof

Abstract

The present application relates to the technical field of wood composite materials, and particularly relates to an environment-friendly moisture-resistant wood core diatomite board and a preparation method thereof.The environment-friendly moisture-resistant wood core diatomite board is a seven-layer composite structure, comprising a wear-resistant layer, a leveling layer, a balancing layer, a stabilizing layer and their symmetrical arrangement from outside to inside, and a modified soy protein-based adhesive is used.The adhesive contains a comb-shaped polymer grafted diatomite, and an amphiphilic polymer layer with hydrophobic alkyl and hydrophilic quaternary ammonium groups is formed on the surface of the diatomite through ATRP grafting method, which not only greatly improves the interfacial bonding force between the diatomite and the wood matrix, but also endows the board with excellent moisture resistance at the molecular level, and simultaneously forms an interpenetrating network with soy protein to construct a multiple waterproof barrier.The present application realizes multiple breakthroughs in the aspects of environmental protection, safety, moisture resistance and structural performance, and provides a new technical path for the high-performance and green application of wood composite materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wood composites, and particularly relates to an environmentally-friendly moisture-resistant wood-core diatomite board and a preparation method thereof. BACKGROUND

[0002] Wood composites have been widely used in the construction, furniture and decoration industries as an important engineering material. In recent years, as an innovative form of wood composites, wood-core diatomite boards have attracted more and more attention due to their unique performance advantages. Wood-core diatomite boards are usually composed of a wood core, diatomite and adhesive, which not only retain the natural beauty and processing performance of wood, but also combine the porous structure and excellent adsorption performance of diatomite, having multiple functions such as humidity regulation, sound absorption and air purification.

[0003] However, traditional wood-core diatomite boards face a serious problem of poor moisture resistance. Wood itself has hydrophilicity, and when exposed to a humid environment, it is easy to absorb water, leading to dimensional changes, warping deformation, and even interlayer peeling and a significant decrease in strength in severe cases. Although diatomite has good moisture absorption, its porous structure without treatment can accelerate the transmission and accumulation of water in the material, further deteriorating the moisture resistance of the material. This defect significantly limits the application of wood-core diatomite boards in high-humidity environments such as kitchens and bathrooms.

[0004] In order to improve the moisture resistance of wood-core diatomite boards, the industry usually adopts the following methods: first, using synthetic resin adhesives with good waterproof performance, such as urea-formaldehyde resin, phenol-formaldehyde resin and melamine-formaldehyde resin; second, hydrophobic modification treatment of diatomite and wood raw materials; third, coating a waterproof coating on the surface of the board. However, these methods have obvious shortcomings. Synthetic resin adhesives have good bonding strength and water resistance, but most of them contain harmful substances such as formaldehyde, which are continuously released during use, causing harm to human health and the environment, which is contrary to the health and environmental protection concept pursued by wood-core diatomite boards. Traditional surface coating of waterproof coating is easy to fail due to wear or aging, and has little effect on the internal moisture resistance of the material.

[0005] As a key component of wood-core diatomite boards, the surface modification of diatomite plays a decisive role in improving the performance of the board. Unmodified diatomite has a rich pore structure and large specific surface area, which is beneficial to enhancing the functionality of the board, but its surface is rich in silicon hydroxyl groups, showing obvious hydrophilicity, which is not conducive to improving the water resistance of the composite material. In addition, diatomite has poor compatibility with organic adhesives, making it difficult to form a firm interface bond, leading to uneven dispersion of fillers and interface stress concentration, ultimately affecting the mechanical properties and service life of the board.

[0006] To overcome the above problems, researchers have tried various ways to modify diatomite. Inorganic salt modification is a common method, such as improving the hydrophobicity and thermal stability of diatomite by treating with aluminum salt and titanium salt. However, this method is easy to introduce heavy metal ions, which has potential environmental risks. Organic silane coupling agent modification can introduce organic functional groups on the surface of diatomite, improving its compatibility with organic matrix, but the traditional modification method can only form a monomolecular layer covering, and the modification effect is limited.

[0007] Therefore, it is urgent to develop a new type of environmentally friendly moisture-resistant wood core diatomite board, which can not only ensure good interface bonding and mechanical properties, but also effectively resist moisture erosion, while avoiding the use of harmful chemicals to the environment and health, to meet the application requirements in high humidity environment. SUMMARY

[0008] Therefore, the purpose of the present application is to provide an environmentally friendly moisture-resistant wood core diatomite board and a preparation method thereof, to solve the problems of poor moisture resistance, insufficient mechanical properties and formaldehyde release of existing wood-based composites.

[0009] Based on the above purpose, the present application provides an environmentally friendly moisture-resistant wood core diatomite board, which comprises a 7-layer structure, from bottom to top, wear-resistant layer, leveling layer, balance layer, stable layer, balance layer, leveling layer and wear-resistant layer.

[0010] Preferably, the wear-resistant layer is a PET film with a thickness of 0.15-0.25mm.

[0011] Preferably, the leveling layer is obtained by hot pressing after laying pine fine material on the surface of the balance layer, and the single-sided laying amount is 300-400g / m 2 .

[0012] Preferably, the particle size of the pine fine material is 0.1-0.3mm.

[0013] Preferably, the balance layer is obtained by coating the slurry prepared by mixing pine fine pieces, diatomite and modified soybean protein-based adhesive with a weight ratio of 60-100:20-40:5-12 on the surface of the stable layer, and cold pressing to shape, with a single-sided coating amount of 2000-2500g / m 2 .

[0014] Preferably, the particle size of the pine fine pieces is 1-3mm.

[0015] Preferably, the modified soybean protein-based adhesive is prepared from the following raw materials by weight: defatted soybean protein powder 10-20 parts, comb-shaped polymer grafted diatomite 30-80g parts, resorcinol diglycidyl ether 1.5-4.5 parts and deionized water 20-50 parts.

[0016] Preferably, the preparation steps of the comb-like polymer grafted diatomite are as follows:

[0017] (1) grafting diatomite by 3-aminopropyl triethoxysilane to obtain aminated diatomite;

[0018] (2) reacting the aminated diatomite with bromoisobutyryl bromide to obtain ATRP initiator grafted diatomite;

[0019] (3) polymerizing lauryl methacrylate on the surface of the ATRP initiator grafted diatomite first, and then polymerizing (3-acrylamidopropyl) trimethylammonium chloride to obtain comb-like polymer grafted diatomite.

[0020] Preferably, the weight ratio of 3-aminopropyl triethoxysilane and diatomite in step (1) is 0.1-1:3-8.

[0021] Preferably, the weight ratio of aminated diatomite and bromoisobutyryl bromide in step (2) is 3-8:0.4-1.2.

[0022] Preferably, the weight ratio of ATRP initiator grafted diatomite, lauryl methacrylate and (3-acrylamidopropyl) trimethylammonium chloride in step (3) is 3-8:20-60:5-20.

[0023] Preferably, the stable layer is a pine wood core.

[0024] Further, the application also provides a preparation method of the environment-friendly moisture-resistant wood core diatomite board, comprising the following steps: mixing pine wood chips and diatomite, adding a modified soybean protein-based adhesive, stirring uniformly to form a slurry; uniformly coating the slurry on both sides of the pine wood core, cold pressing and shaping at 0.6-1 MPa for 8-12 min to form a balance layer; laying pine wood fines on the surface of the balance layer, the single-side laying amount being 300-400 g / m 2 , hot roll stretching at 115-125 ℃ for 3-8 s to form a flat layer; covering PET film on the surface of the flat layer, one layer on each side, hot pressing at 125-135 ℃ and 0.8-1.2 MPa for 12-18 min to obtain a composite board, and finally curing the composite board in an oven at 48-52 ℃ for 20-28 h, cutting to the target size to obtain the environment-friendly moisture-resistant wood core diatomite board.

[0025] The application has the following beneficial effects:

[0026] Firstly, the present application adopts ATRP grafting technology to construct a comb-like polymer layer with a specific structure on the surface of diatomite. This comb-like polymer layer forms a stable covalent bond connection with diatomite, ensuring the long-term stability of the modified filler in the composite system. At the same time, the flexible structure of the polymer side chain enhances the compatibility of the filler with the wood matrix, reduces the interfacial defects, and improves the mechanical properties and structural stability.

[0027] Secondly, the present application creatively introduces hydrophobic long-chain alkyl and hydrophilic quaternary ammonium groups into the comb-like polymer structure, forming a unique amphiphilic molecular structure. This molecular design achieves a precise balance between hydrophobicity and hydrophilicity: on the one hand, the hydrophobic long-chain alkyl forms a continuous hydrophobic barrier through self-assembly, effectively blocking water molecules from penetrating; on the other hand, the hydrophilic quaternary ammonium groups form electrostatic interactions and hydrogen bond networks with the hydroxyl and carboxyl groups on the wood surface, enhancing the interfacial bonding force. This molecular-level synergistic effect significantly improves the water resistance and interfacial stability of the material.

[0028] Thirdly, the present application utilizes the synergistic effect of comb-like polymer grafted diatomite and soy protein to construct a composite adhesive system with a network interpenetrating structure. During hot pressing, the soy protein molecular chains and polymer side chains undergo physical entanglement and chemical crosslinking, forming a three-dimensional network structure. This network structure not only enhances the internal bonding force of the material, but also forms a multi-barrier system, forcing water molecules to diffuse along a circuitous path, thereby significantly slowing down the water penetration rate.

[0029] Fourthly, the present application completely avoids the use of harmful substances such as formaldehyde, and uses renewable soy protein as the main adhesive component, combined with environmentally friendly modification technology, to achieve green environmental protection of the material. This not only helps to improve indoor air quality and protect the health of users, but also conforms to the concept of sustainable development, with significant social and environmental benefits.

[0030] Fifthly, the product of the present application exhibits excellent dimensional stability and strength retention in a humid environment. Even under long-term water immersion conditions, the material can still maintain a low thickness expansion rate and a high strength retention rate, which is a breakthrough for wood composites. This excellent moisture resistance greatly expands the application field of wood composites, enabling them to meet the use requirements in high-humidity environments such as kitchens and bathrooms.

[0031] In summary, the environmentally friendly moisture-resistant wood core diatomite board provided by the present application achieves the unity of environmental protection, mechanical properties, and moisture resistance through molecular-level structural design and multi-functional synergistic mechanism, providing new ideas and methods for the high-performance and functionalization of wood composites. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with specific examples.

[0033] The diatomite in the present application is purchased from Shengzhou Huali Diatomite Products Co., Ltd., with a model number of CD04, a mesh number of 500-1000, SiO2≥89%, a pH value of 5-8, a moisture content of <2%, and a loss on ignition of ≤1%; and the defatted soybean protein powder is purchased from Shandong Sanwei Soybean Protein Co., Ltd.

[0034] Example 1

[0035] (1) 3 g of diatomite was added into a mixture of 35 g of deionized water and 15 g of anhydrous ethanol, and ultrasonically dispersed for 20 min, then 0.1 g of 3-aminopropyl triethoxysilane was added, and the temperature was raised to 53℃, and stirred for 5 h, and then centrifuged, washed with anhydrous ethanol for 3 times, and vacuum dried at 60℃ for 12 h to obtain aminated diatomite;

[0036] (2) Under a nitrogen atmosphere, 3 g of aminated diatomite was added into 30 g of tetrahydrofuran, and ultrasonically dispersed at 0℃ for 20 min, then 0.2 g of triethylamine and 0.4 g of bromoisobutyryl bromide were added, and the temperature was raised to room temperature, and stirred for 30 h, and then centrifuged, and washed with tetrahydrofuran and acetone for 3 times respectively, and vacuum dried at 60℃ for 12 h to obtain ATRP initiator grafted diatomite;

[0037] (3) Under a nitrogen atmosphere, 3 g of ATRP initiator grafted diatomite, 20 g of lauryl methacrylate, 0.005 g of cuprous bromide, and 0.02 g of N,N,N',N'',N''',N'''-hexamethyltris(2-aminoethyl)amine were added into 30 g of anhydrous toluene, and the temperature was raised to 108℃, and stirred for 10 h, then 5 g of (3-acrylamidopropyl)trimethylammonium chloride was added, and stirred for 5 h, and then centrifuged, and washed with anhydrous toluene and anhydrous methanol for 3 times respectively, and vacuum dried at 60℃ for 12 h to obtain comb-shaped polymer grafted diatomite;

[0038] (4) 10 g of defatted soybean protein powder was added into 20 g of deionized water, and stirred at room temperature for 8 min, then 30 g of comb-shaped polymer grafted diatomite and 1.5 g of resorcinol diglycidyl ether were added, and stirred for 25 min to obtain a modified soybean protein-based adhesive.

[0039] (5) 600 g of pine wood chips (particle size 1-3 mm) were mixed with 200 g of diatomite, and 50 g of the modified soybean protein-based adhesive was added, and stirred uniformly to form a slurry; the slurry was uniformly coated on both sides of a pine wood core (size 400 mm x 200 mm x 15 mm), and the coating amount on a single side was 2000 g / m 2, 0.6 MPa cold pressure setting 8 min, forming a balance layer; in the balance layer surface paving pine fine (particle size 0.1 mm), single paving amount is 300 g / m 2 , 115 ℃ hot roller 3 s, forming a smooth layer; the PET film (thickness 0.2 mm) is covered on the surface of the smooth layer (double 1 layer), 125 ℃, 0.8 MPa hot pressing 12 min, the composite board is obtained, and finally the composite board is placed in a 48 ℃ oven for curing 20 h, and is cut to the target size to obtain an environmentally friendly moisture-resistant wood core diatomite board.

[0040] Example 2:

[0041] (1) 5 g of diatomite was added to a mixture of 70 g of deionized water and 30 g of anhydrous ethanol, and ultrasonic dispersion was performed for 30 min. Then, 0.5 g of 3-aminopropyl triethoxysilane was added, and the temperature was raised to 55 ℃. Stirring reaction was performed for 6 h. Centrifugal separation was performed, and washing was performed three times with anhydrous ethanol. Vacuum drying was performed at 60 ℃ for 12 h to obtain aminated diatomite.

[0042] (2) Under a nitrogen atmosphere, 5 g of aminated diatomite was added to 50 g of tetrahydrofuran, and ultrasonic dispersion was performed for 30 min at 0 ℃. Then, 0.4 g of triethylamine and 0.8 g of bromoisobutyryl bromide were added, and the temperature was raised to room temperature. Stirring reaction was performed for 36 h. Centrifugal separation was performed, and washing was performed three times with tetrahydrofuran and acetone, respectively. Vacuum drying was performed at 60 ℃ for 12 h to obtain ATRP initiator grafted diatomite.

[0043] (3) Under a nitrogen atmosphere, 5 g of ATRP initiator grafted diatomite, 40 g of lauryl methacrylate, 0.01 g of cuprous bromide, and 0.05 g of N,N,N',N'',N''',N'''-hexamethyl triethylene tetramine were added to 50 g of anhydrous toluene. The temperature was raised to 110 ℃, and stirring reaction was performed for 12 h. Then, 10 g of (3-acrylamidopropyl) trimethylammonium chloride was added, and stirring was continued for 6 h. Centrifugal separation was performed, and washing was performed three times with anhydrous toluene and anhydrous methanol, respectively. Vacuum drying was performed at 60 ℃ for 12 h to obtain comb-shaped polymer grafted diatomite.

[0044] (4) 15 g of defatted soybean protein powder was added to 35 g of deionized water, and stirring was performed at room temperature for 10 min. Then, 50 g of comb-shaped polymer grafted diatomite and 3 g of resorcinol diglycidyl ether were added, and stirring was continued for 30 min to obtain a modified soybean protein-based adhesive.

[0045] (5) 800 g of pine fine pieces (particle size 1-3 mm) were mixed with 300 g of diatomite, and 80 g of the modified soybean protein-based adhesive was added. After uniform stirring, a slurry was formed. The slurry was uniformly coated on both surfaces of a pine wood core (specification 400 mm×200 mm×15 mm), and the single-side coating amount was 2200 g / m 2, 0.8 MPa cold pressure setting 10 min, forming a balance layer; in the balance layer surface paving pine fine (particle size 0.1-0.3mm), single paving amount is 350g / m 2 , 120℃ hot roller 5s, forming a smooth layer; the PET film (thickness 0.2mm) is covered on the surface of the smooth layer (double 1 layer), 130℃, 1.0 MPa hot pressing 15min, the composite board is obtained, and finally the composite board is placed in a 50℃ oven for curing 24h, cut to the target size, and the environment-friendly moisture-resistant wood core diatomite board is obtained.

[0046] Example 3:

[0047] (1) 8g diatomite was added into a mixture of 105g deionized water and 45g anhydrous ethanol, and ultrasonic dispersion was carried out for 40min, then 1g 3-aminopropyl triethoxysilane was added, the temperature was raised to 58℃, and stirring reaction was carried out for 7h, centrifugal separation was carried out, and washing was carried out with anhydrous ethanol for 3 times, and vacuum drying was carried out at 60℃ for 12h, to obtain aminated diatomite;

[0048] (2) Under the nitrogen atmosphere, 8g aminated diatomite was added into 80g tetrahydrofuran, and ultrasonic dispersion was carried out at 0℃ for 40min, then 0.6g triethylamine and 1.2g bromoisobutyryl bromide were added, the temperature was raised to room temperature, and stirring reaction was carried out for 40h, centrifugal separation was carried out, and washing was carried out with tetrahydrofuran and acetone for 3 times respectively, and vacuum drying was carried out at 60℃ for 12h, to obtain ATRP initiator grafted diatomite;

[0049] (3) Under the nitrogen atmosphere, 8g ATRP initiator grafted diatomite, 60g lauryl methacrylate, 0.015g cuprous bromide and 0.08g N,N,N',N'',N''',N'''-hexamethyl triethylene tetramine were added into 80g anhydrous toluene, the temperature was raised to 112℃, and stirring reaction was carried out for 14h, then 20g (3-acrylamidopropyl) trimethylammonium chloride was added, and stirring was continued for 7h, centrifugal separation was carried out, and washing was carried out with anhydrous toluene and anhydrous methanol for 3 times respectively, and vacuum drying was carried out at 60℃ for 12h, to obtain comb-shaped polymer grafted diatomite;

[0050] (4) 20g defatted soybean protein powder was added into 50g deionized water, stirring was carried out at room temperature for 12min, then 80g comb-shaped polymer grafted diatomite and 4.5g resorcinol diglycidyl ether were added, and stirring was continued for 35min, to obtain modified soybean protein-based adhesive.

[0051] (5) 1000g pine fine pieces (particle size 1-3mm) were mixed with 400g diatomite, 120g modified soybean protein-based adhesive was added, and stirring was carried out uniformly to form a slurry; the slurry was uniformly coated on both surfaces of pine wood core (specification 400mm×200mm×15mm), and the single surface coating amount was 2500g / m 2, 1 MPa cold pressure setting 12 min, forming a balanced layer; on the surface of the balanced layer laid pine fines (0.3 mm), single side paving amount is 400 g / m 2 , 125 ℃ hot roller 8 s, forming a smooth layer; the PET film (thickness 0.2 mm) is covered on the surface of the smooth layer (1 layer on both sides), 135 ℃, 1.2 MPa hot pressing 18 min, to get the composite board, finally the composite board is placed in a 52 ℃ oven curing 28 h, cut to the target size, to get the environmentally friendly moisture-resistant wood core diatom board.

[0052] Comparative Example 1:

[0053] The difference between Comparative Example 1 and Example 2 is that (3-acrylamidopropyl) trimethylammonium chloride in step (3) is replaced by lauryl methacrylate.

[0054] Comparative Example 2:

[0055] The difference between Comparative Example 2 and Example 2 is that lauryl methacrylate in step (3) is replaced by (3-acrylamidopropyl) trimethylammonium chloride.

[0056] Comparative Example 3:

[0057] The difference between Comparative Example 3 and Example 2 is that the comb-shaped polymer grafted diatomite in step (4) is replaced by diatomite.

[0058] Comparative Example 4:

[0059] The difference between Comparative Example 4 and Example 2 is that lauryl methacrylate in step (4) is replaced by methyl methacrylate.

[0060] Performance test:

[0061] Mechanical properties: according to GB / T 17657-2013, the bending performance test uses a universal material testing machine, the loading speed is 10 mm / min, the bending strength is measured, the internal bonding strength test uses the tensile test of the adhesive area of the thickness section, the loading speed is 1 mm / min, the maximum breaking tension is recorded, and the internal bonding strength is calculated.

[0062] Water resistance: according to GB / T 17657-2013, the sample is completely immersed in water at (20±1) ℃ for 24 h, and the surface moisture is immediately wiped dry after taking out, the thickness and internal bonding strength of the sample are measured within 10 min, and the thickness expansion rate and internal bonding strength reduction rate are calculated, the values are expressed as the relative change percentage before and after immersion.

[0063] Table 1 Performance test results

[0064]

[0065] Data analysis:

[0066] From the data in Table 1, it can be seen that the environmentally friendly moisture-resistant wood core diatomite board prepared by the present application exhibits excellent comprehensive performance. The better bending strength indicates that the material has good structural stability, which may be due to the three-dimensional network interpenetrating structure formed by the comb-shaped polymer grafted diatomite and wood fibers, and the interface bonding is enhanced by the electrostatic action of the quaternary ammonium group and the wood surface hydroxyl group. The lower internal bonding strength decline rate indicates that the material has significant water resistance, which may be due to the hydrophobic-hydrophobic synergistic effect of the long alkyl chain of lauryl methacrylate and the hydrophobic chain of soybean protein, effectively blocking water penetration. At the same time, the lower thickness expansion rate further proves that the dense barrier structure formed by hydrophobic modification inhibits the swelling effect of water on the material body. The overall performance improvement may be attributed to the reasonable configuration of the hydrophilic / hydrophobic groups in the polymer molecular chain, which not only maintains the affinity with the wood components, but also builds a continuous water-resistant barrier.

[0067] Compared with Comparative Example 1 containing only hydrophobic chains, Example 2 has obvious advantages in mechanical properties and water resistance. This difference may be due to the introduction of quaternary ammonium groups enhancing the interface bonding mechanism: cationic quaternary ammonium groups interact with the surface of wood fibers to form more stable molecular level bonding points.

[0068] When compared with Comparative Example 2 lacking hydrophobic chains, Example 2 exhibits better dimensional stability and water resistance retention. The data difference indicates that the long alkyl hydrophobic chain forms a continuous water-resistant barrier through molecular chain entanglement: the strong hydrophobic association between the long alkyl chain of lauryl methacrylate and the hydrophobic region of soybean protein forms a microphase separation structure. This structure is oriented and arranged during hot pressing, forming a dense layered protection system that can effectively block the water penetration path. Especially under water immersion conditions, the hydrophobic association force of the molecular chain resists the desorption of water molecules on the polymer-wood interface, thus significantly reducing the water-induced plasticization effect and strength decay rate of the material.

[0069] The performance disadvantage of Comparative Example 3 reveals the key role of diatomite grafting modification: unmodified diatomite only has a physical filling effect, while comb-shaped polymer grafting achieves chemical bonding enhancement. The anchoring effect of polymer side chains with wood fibers may be achieved through two mechanisms: on the one hand, ATRP initiation sites ensure covalent connection between polymer chains and the surface of diatomite, enhancing the interface stress transfer efficiency; on the other hand, the conformational extension of the grafted segment increases the contact area with wood, producing stronger van der Waals force adsorption. This multi-level bonding structure can effectively disperse stress when under pressure, and buffer the impact of water molecules when under moisture, thus simultaneously improving the dry strength and wet stability.

[0070] Compared with Comparative Example 4 of short-chain methyl methacrylate modification, Example 2 using long alkyl chain monomers shows better moisture resistance. This can be due to the unique self-assembly behavior triggered by the steric effect of long alkyl chains: the C12 alkyl group of lauryl ester is orderly packed during hot pressing, forming a hydrophobic microzone with higher crystallinity. This ordered structure enhances the cohesive force between molecular chains, while reducing the free volume fraction, thus more effectively inhibiting the diffusion dynamics of water molecules. Especially during water immersion, the long alkyl chain maintains a close stacking state through conformational adjustment, forming a dynamic hydrophobic barrier, showing stronger plasticization resistance and interface stability compared with the short-chain system.

[0071] It should be understood by those of ordinary skill in the art that the above discussion of any of the embodiments is merely exemplary and is not intended to suggest that the scope of the application is limited to these examples; under the concept of the application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the application as described above. In order to be brief, they are not provided in detail.

Claims

1. An environmentally friendly, moisture-resistant wood-core diatomaceous earth board, characterized in that, The structure comprises seven layers, from bottom to top: a wear-resistant layer, a smoothing layer, a balancing layer, a stabilizing layer, a balancing layer, a smoothing layer, and another wear-resistant layer. The balancing layer is prepared by coating a slurry made from a mixture of pine wood chips, diatomaceous earth, and modified soybean protein-based adhesive in a weight ratio of 60-100:20-40:5-12 onto the surface of the stabilizing layer, followed by cold pressing. The coating weight on one side is 2000-2500 g / m². 2 ; The modified soybean protein-based adhesive is prepared from the following raw materials in parts by weight: 10-20 parts defatted soybean protein powder, 30-80 g parts comb-like polymer-grafted diatomaceous earth, 1.5-4.5 parts resorcinol diglycidyl ether, and 20-50 parts deionized water. The preparation steps of the comb-shaped polymer-grafted diatomite are as follows: (1) Diatomite was grafted with 3-aminopropyltriethoxysilane to obtain aminated diatomite; (2) ATRP initiator-grafted diatomaceous earth was obtained by reacting aminated diatomaceous earth with bromoisobutyryl bromide. (3) First, methyl lauryl methacrylate is polymerized on the surface of diatomaceous earth grafted with ATRP initiator, and then (3-acrylamidopropyl)trimethylammonium chloride is polymerized to obtain comb-like polymer grafted diatomaceous earth.

2. The environmentally friendly, moisture-resistant wood-core diatomaceous earth board according to claim 1, characterized in that, The wear-resistant layer is a PET film with a thickness of 0.15-0.25 mm.

3. The environmentally friendly, moisture-resistant wood-core diatomaceous earth board according to claim 1, characterized in that, The leveling layer is obtained by hot pressing fine pine wood onto the surface of the balancing layer, with a single-sided application rate of 300-400 g / m². 2 .

4. The environmentally friendly, moisture-resistant wood-core diatomaceous earth board according to claim 3, characterized in that, The particle size of the pine wood fines is 0.1-0.3 mm.

5. The environmentally friendly, moisture-resistant wood-core diatomaceous earth board according to claim 1, characterized in that, The particle size of the pine wood chips is 1-3 mm.

6. The environmentally friendly, moisture-resistant wood-core diatomaceous earth board according to claim 1, characterized in that, In step (1), the weight ratio of 3-aminopropyltriethoxysilane to diatomaceous earth is 0.1-1:3-8.

7. The environmentally friendly, moisture-resistant wood-core diatomaceous earth board according to claim 1, characterized in that, In step (2), the weight ratio of aminated diatomaceous earth to bromoisobutyryl bromide is 3-8:0.4-1.

2.

8. The environmentally friendly, moisture-resistant wood-core diatomaceous earth board according to claim 1, characterized in that, In step (3), the weight ratio of ATRP initiator grafted diatomaceous earth, lauryl methacrylate, and (3-acrylamidopropyl)trimethylammonium chloride is 3-8:20-60:5-20.

9. The environmentally friendly, moisture-resistant wood-core diatomaceous earth board according to claim 1, characterized in that, The stabilizing layer is made of pine wood core.

10. A method for preparing an environmentally friendly, moisture-resistant wood-core diatomaceous earth board according to any one of claims 1-9, characterized in that, Includes the following steps: Mix pine wood chips with diatomaceous earth, add modified soybean protein-based adhesive, and stir evenly to form a slurry. Apply the slurry evenly to both sides of the pine wood core and cold press at 0.6-1MPa for 8-12 minutes to form a balance layer. Lay pine wood chips on the surface of the balance layer and hot roll calender at 115-125℃ for 3-8 seconds to form a flat layer. Cover the flat layer with PET film, one layer on each side, and hot press at 125-135℃ and 0.8-1.2MPa for 12-18 minutes to obtain a composite board. Finally, place the composite board in an oven at 48-52℃ to cure for 20-28 hours, and cut it to the target size to obtain an environmentally friendly and moisture-resistant wood core diatomaceous earth board.

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